GL-EA-010_Companion Guide for Testing of Assets

Transcription

1 GL-EA-010_Companion Guide for Testing of Assets System Operator Transpower New Zealand Limited August 2016 The contents of this document may not be Transpower's final or complete view on any particular subject, and all provisions of it are subject to change. Transpower as the system operator excludes all representations and warranties relating to the contents of this document, including in relation to any inaccuracies or omissions. The Transpower excludes all liability for loss or damage arising from any person's reliance on the contents of this document

2 2 PDF Created on: 01/05/17 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets Overview TABLE OF CONTENTS 1 About this Document Overview Generator Tests Generators Tests for Equipment Covered by Ancillary Service Contracts Grid Owner Tests Grid Owner Distributor Tests Distributors Tests for Equipment Covered by Ancillary Contracts Guide for testing Examples and theory Overview Generating Unit Parameters Transformers Generator Frequency Performance Generating/Synchronous-compensating Unit Exciter/AVR and Voltage Control Generating Unit Governor/Turbine and Frequency Control Frequency Keeping Example injection curves Instantaneous Reserve - Generator FIR/SIR capability Transmission Line HVDC AUFLS Distributor Reserve Capability... 59

3 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 About this DocumentAbout this Document Overview 3 Glossary of Terms Acronym Version Control ACS AOPO AUFLS AVR CCGT CIGRE Code CT DAO FIR GAO GXP GIP HVDC PPO OEL SIR SVC UEL VT Asset Capability Statement Asset Owner Performance Obligations Automatic Under Frequency Load Shedding Automatic Voltage Regulator Combined Cycle Gas Turbine International Council on Large Power Systems (Conseil International des Grands Réseaux Electriques) Electricity Industry Participants code Current Transformer Distributor Asset Owner Fast Instantaneous Reserve Generator Asset Owner Grid Exit Point Grid Injection Point High Voltage Direct Current Principal Performance Obligations Over Excitation Limit Sustained Instantaneous Reserve State VAR Compensator Under Excitation Limit Voltage Transformer Date Version 30/8/07 V01 Approved Re-written as Explanatory Guide after Rule Change. Split into three sections that are categorised by asset owner category 01/11/10 V02 12/06/12 V03 Amended to reflect change from Rule to Code references due to formation of the Electricity Authority Updates to tests and methodology. 8/10/12 V04 4/8/ Updated after consultation for version 3 Additional information from consultation added. Updates to AUFLS Relay Testing Guidelines to assist in preparations for Efficient Procurement of Extended Reserves Acknowledgements The system operator, in preparing this document, wishes to acknowledge the valuable technical assistance and positive feedback from many asset owners, technical consultants and the Electricity Authority. It would have not been possible to produce this document without the active participation of industry stakeholders.

4 4 PDF Created on: 01/05/17 About this Document Overview Doc File Name: GL-EA-010_Companion Guide for Testing of Assets 1 ABOUT THIS DOCUMENT 1.1 OVERVIEW This Companion Guide for Testing of Assets (Explanatory Guide) provides guidance on: test objectives and required test results for routine tests and commissioning tests for assets including those which are the subject of an ancillary services procurement contract types of tests that could be carried out to achieve the test objective relevant standards and codes to assist asset owners in formulating test plans specific to their assets and circumstances. The system operator needs to be involved with the planning and coordination of all tests whilst connected to the power system that may impact the SO s ability to comply, or plan to comply with the PPO s. The System Operator should also be informed about all offline tests that are to ascertain or confirm asset capability. This Explanatory Guide will be formally reviewed as provided for in current and future Policy Statements for the currency and appropriateness of the technical information contained in the document. At the time of each review, the system operator will seek industry feedback on the content of the Explanatory Guide. The Explanatory Guide sets out the tests considered appropriate by the system operator for asset owners to demonstrate asset compliance with the AOPOs and technical codes. It sets out: the type of test required for each type of asset the output required from each test The guide does not define the achievement criteria for the tests that are performed. The tests and required output included in this document have been determined taking into account: the relative importance of various asset data to the system operator in meeting its PPOs the practicality of performing the required tests the impact performing the tests will have on the system operator s ability to meet its PPOs during such testing the impact performing the tests will have on the asset itself International standards and best practices, customised for New Zealand power system conditions as required. Assets with control functions such as AUFLS, AVRs, governors, SVC, and the HVDC link play a key role in the dynamic control and stability of the grid. The parameters and modelling techniques used to model these assets are therefore critical to the system operator s ability to comply with its PPOs. Therefore, they are subject to more detailed test requirements.

5 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 About this Document Overview 5 The code requires the submission of an updated asset capability statement (ACS) within 3 months following any tests. In a number of cases, the test results will need to be provided as part of the updated ACS. The code allow the system operator to ask for any other information that it reasonably requires to plan to comply and comply with the PPOs This document does not seek to alter any obligations on asset owners or the system operator in any way from those detailed in the Electricity Industry Participation Code 2010 or its amendments. In any perceived conflict between it and the Code, the Code should take precedence. This document does not relieve asset owners of the need to read, understand and comply with asset owner obligations set out in the Electricity Industry Participation Code Data resolution needs to be of adequate precision to identify any dynamic response of the equipment in question. When a model is required for the equipment, the types of data to be measured are dependent on the models requirements/inputs, which ultimately need to mimic the results seen in the tests. It is advised that the model of the equipment be constructed before testing so the measurement requirements are fully defined. This document is arranged by asset owner Type. The main body of the document outlines requirements of the asset owner, with the appendix offering examples of how these requirements could be met.

6 6 PDF Created on: 01/05/17 Generator Tests Generators Doc File Name: GL-EA-010_Companion Guide for Testing of Assets 2 GENERATOR TESTS 2.1 GENERATORS Overview This section details the tests required from generators to meet the requirements in Part 8 of the Code Application The generator tests apply to all generators above 1 MW. A lesser quantity of tests may be appropriate if the generator does not have frequency or voltage obligations. Consult the system operator if this applies Required Outcome Generator tests are carried out to provide sufficient information (as determined by control system and plant settings and parameters) to verify: operational ranges and limits of the generating plant steady state and dynamic performance of the plant in both linear and non-linear regions for generators with frequency obligations over/under frequency performance including trip settings compliance of protection systems with the protection related AOPOs and technical codes Representative Testing The Routine Testing Appendix in Part 8 of the Code lists requirements should representative testing be considered to reduce the burden of testing. CONTENTS Generating Unit Parameters Generating Unit Frequency Performance and Trip Settings Generating Unit Governor/Turbine and Frequency Control Generating Unit Transformer Voltage Control Generating Unit Voltage Response and Control... 11

7 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Generator Tests Generators Content This section describes the outcome and test/information requirements for the generating unit parameter tests and details of tests that will achieve the required outcome. Parameters supplied by manufacturers are also acceptable if they are the most recent and most accurate data available Application Information on generator ratings is required from all generators above 1MW in size, before commissioning. During commissioning, one set of test results, either from the manufacturer or from a site test is sufficient providing the parameters are fixed with the construction of the machine and do not change significantly at the commissioning stage (very rarely changes). Re-testing is required when the machine undergoes: a major overhaul which changes data reported in the ACS stator and/or rotor rewinding/replacement re-rating modification, or at any other time where machine characteristics have changed from the data last reported in the ACS Wherever a few key variables can give a good indication of the unit s parameters, re-testing may use a subset of tests based on these key variables to obtain a representative set of parameters required to confirm that the asset characteristics remain unchanged. Consultation with system operator is required to determine if subset testing is applicable. Any large deviations of these parameters between the measured and previously recorded data may prompt the repeat of a full set of tests Purpose of test To verify the mathematical model that describes the unit s steady state and dynamic behaviour, generator unit parameter testing is required. A model of the generating unit is fundamental to any dynamic stability studies as well as load flow and fault studies. For example, in the case of synchronous generators, the standard 2-axes model is used, which is well documented in standards and literature Test outcome The tests are required to provide: characteristic curves which include a: Capability diagram open & short circuit curves V-curve zero power factor curve unbalanced load-time curve machine reactances machine time constants saturation data ACS Reference The information is required in the ACS

8 8 PDF Created on: 01/05/17 Generator Tests Generators Doc File Name: GL-EA-010_Companion Guide for Testing of Assets Tests that will achieve required outcome Appropriate tests can be found in the appendix (Guide for testing): 5.2 Generating Unit Parameters Content This section describes the outcome and test/information requirements for the under/over frequency relay tests, which involves the tripping of the machine. It also includes the requirements for testing under frequency response on gas turbines Application The testing in this section applies to all generators, except for owners of excluded generating stations, unless the Electricity Authority has issued a directive under Part 8 of the Code. The generators which do not have frequency obligations and are excluded from testing are still required to provide trip setting information. These tests are required whilst commissioning, when modifying plant, and routinely to ensure the plant meets the required specifications. This is likely to be the case subsequent to the following events: where the relay, instruments, circuit breaker or any associated communication equipment differs from the original specification following any maintenance or servicing that involves major components of the over/under frequency trip system routinely with a test interval as detailed in The Routine Testing appendix in Part 8.3 Appendix B of the Code These tests should not be performed when the generator is online Purpose of tests To confirm the over- and under-frequency trip settings and time delays. To confirm the unit under-frequency performance Test Outcomes These tests should provide two sets of outcomes. The asset owner is required to provide results consisting of relay injection tests and/or frequency response of the generator to demonstrate: the under-frequency trip settings and time delays, including the relay and breaker tripping times the over-speed/frequency trip settings (both mechanical overspeed and electrical over-frequency), including the relay and breaker tripping times The asset owner of a gas turbine is also required to provide, but not prove, a frequency response curve showing output power versus frequency (with time delays clearly shown) over a range of frequencies around nominal frequency. This curve can come from manufacturer capability curves and capability sheets or charts ACS reference The information is required in the ACS

9 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Generator Tests Generators Tests that will achieve required outcome Appropriate tests can be found in the appendix (Guide for testing): 5.4 Generator Frequency Performance Content This section describes the test requirements for the Governor/Turbine and frequency control system tests Application Testing is required for all generators except for owners of excluded generating stations, unless the Electricity Authority has issued a directive under Part 8 of the Code. Modelling and testing is required for all utilised control blocks that have an impact on system frequency. Testing is required during commissioning, when a plant has been in service for an extended period and requires routine testing, or when modifying plant or associated equipment. This is likely to be the case subsequent to the following events: following any maintenance or servicing that involves major components of the speed-governing system or the mechanical driver that may change the response of the machine where the governor/frequency control equipment has significantly changed (prior agreement with the System Operator is required before any setting change can be made [See Part 8 of the Code ]) where the governor/frequency control equipment differs from the original specification routinely with a test interval as detailed in The Routine Testing appendix in Part 8 of the Code Purpose of test The generating-unit governor and frequency control testing is required to demonstrate the unit s frequency response characteristics. This allows accurate steady state and dynamic frequency control modelling. These models are integrated into a wide area network model, which allows the frequency of the system to be controlled and managed within the defined stability limits Test outcome The asset owner will be required to provide: a block diagram showing the verified (through testing) mathematical representation of the particular manufacturer s model of governor or frequency control system installed on the generating unit. This includes all linear, non-linear and discontinuous control blocks inherent to governor or frequency control. Model verification is based on end-toend performance. a block diagram showing the verified (through testing) mathematical representation of the turbine dynamics including non-linearity (e.g. gate or valve versus turbine power tabular relationship), and applicable fuel source (e.g. steam, gas, hydraulic, wind) dynamics. Verification is based on end-to-end performance.

10 10 PDF Created on: 01/05/17 Generator Tests Generators Doc File Name: GL-EA-010_Companion Guide for Testing of Assets a parameter list showing gains, time constants, and other settings specifically applicable to both block diagrams above. results consisting of step responses and/or frequency response, as electronic data, of the governor or frequency control device to verify: the tuning and stability of the standard control system the performance of feed forward control blocks (under-frequency management) if applicable the over-frequency response (to ensure it is the same as under frequency) the performance of any other discontinuous control blocks (i.e. deadband) a description of the governor functionality describing the mode of operation available and when each mode is utilised. Clearly note any functionality that is not utilised. Data resolution for these tests is plant-specific and can t be prescribed by the System Operator, however it needs to be sufficient to adequately demonstrate the dynamic response from the governor or frequency control system. The measured data types are dependent on the models requirements/inputs, which ultimately need to mimic the results seen in the tests. It is preferred that the model is constructed before testing so the measurement requirements are fully defined. It is the asset owner s responsibility to verify the tuning parameters of their model before submitting it to the system operator ACS Reference This information is required in the ACS Tests that will achieve required outcome Appropriate tests and examples can be found in the appendix (Guide for testing): Governor Block Diagrams/Models Governor Stability Example governor frequency injection curves Content This section describes the test/information requirements for a generating unit transformer with respect to voltage support Application This section applies to all generator transformers with a point of connection to the grid. Routing testing applies to all transformers with on-load tap-changers that operate to a voltage set point in automatic voltage control. Transformer testing should occur during commissioning, when modifying plant or associated equipment, or has been in service for an extended period and require routine testing. This is likely to be the case subsequent to the following events: where the transformer equipment has significantly changed (including tap changers, transformer bushings, earthing resistors and reactors, or cooling systems) following any maintenance or servicing that involves major components of the transformer

11 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Generator Tests Generators 11 where the transformer control equipment differs from the original specification routinely with a test interval as detailed in the Routine Testing appendix in Part 8 of the Code If nameplate and manufacturer information is available, no further testing of the construction parameters will be required (i.e. impedances) Purpose of test The transformer data is required to assess the ability of transformer units to maintain point of supply voltage and reactive power capability within applicable limits Test outcome (routine testing) The testing will result in verification of the control system of on load tap changers (that automatically operate to a voltage set point) at a controlled node of the grid. This testing includes: voltage set points operating deadband response times ACS Reference The information is required in the ACS Tests that will achieve required outcome Appropriate tests can be found in the appendix (Guide for testing) Routine Tests: Tap Changers Routine Testing Commissioning Tests: General Transformer Data - Commissioning Resistance and Reactance - Commissioning Content This section describes the test and information requirements for the generating units voltage-response and control, and any voltage control system external to the unit Application This section applies to all generators with a point of connection to the grid. The voltage control system/avr and exciter should be tested during commissioning, where the model and/or parameters have been changed, or has been in service for extended period and require routine testing. This is likely to be the case: following any maintenance or servicing that involves major components of the excitation or AVR/voltage control system where the exciter or AVR/voltage control equipment has significantly changed where the exciter or AVR/voltage control equipment differs from the original specification routinely with a test interval as detailed in the Routine Testing appendix in Part 8 of the Code

12 12 PDF Created on: 01/05/17 Generator Tests Generators Doc File Name: GL-EA-010_Companion Guide for Testing of Assets Purpose of test The generating-unit voltage-response and control testing is required to allow accurate steady state and dynamic modelling. These models are integrated into a network wide model, which allows secure and stable operation of the national grid. An accurate representation: demonstrates asset owner compliance with AOPO s and technical codes allows the system operator to model interaction of the asset with the grid and other generating stations when subjected to disturbances on the system. Such modelling assists with control of voltage stability Test outcomes The asset owner will be required to provide: a block diagram showing the verified (through end-to-end testing) mathematical representation of the particular manufacturer s model of AVR/voltage control system and exciter. This includes all non-linear and discontinuous control blocks of the AVR/control system (i.e. OEL, UEL, PSS). See IEEE Std for more information. a parameter list showing gains, time constants, and other settings applicable to the block diagram above. results consisting of step responses and/or voltage response, as electronic data, of the AVR or voltage control device to verify: the tuning and stability of the standard functionality of the control system the over excitation limit (OEL) of the control system where implemented the under excitation limit (UEL) of the control system where implemented the power system stabiliser (PSS), including MW and MVAr output during test, if applicable. any other discontinuous control block (I.E deadband) More information can be found in IEEE Std Data resolution needs to be of adequate precision to identify any dynamic response from voltage control/avr system. The measured data types are dependent on the models requirements/inputs, which ultimately need to mimic the results seen in the tests. It is preferred that the model is constructed before testing so the measurement requirements are fully defined. It is the asset owner s responsibility to verify the tuning parameters of their model before submitting it to the system operator ACS Reference The information is required in the ACS Tests that will achieve required outcome Appropriate tests can be found in the appendix (Guide for testing) Synchronous Machine Exciter Block Diagrams/Models Asynchronous Machine Voltage Control Block Diagrams/Models

13 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Generator Tests Tests for Equipment Covered by Ancillary Service Contracts TESTS FOR EQUIPMENT COVERED BY ANCILLARY SERVICE CONTRACTS Purpose This section details some of the tests required to meet Code requirements (Procurement Plan) for testing of the ancillary services. The tests listed in this section ONLY apply to generators with the specified ancillary service contracts Type Testing Type or Representative testing is generally not applicable to generators providing ancillary services but could be allowed on a case-by-case basis depending on the nature of the Contract covering the ancillary service Application This section applies to all equipment offered under the ancillary services contract. The section does not seek to alter any obligations on asset owners detailed in their ancillary services contracts. If any conflicts exist, the contract conditions take precedence. CONTENTS Frequency Keeping for Single Frequency Keepers Over-frequency arming Instantaneous Reserve Voltage Support Black Start Definition The provision of spare synchronised capacity to match variations between dispatched generation and load Application These tests are for generators who offer into the single frequency keeper market. These tests are not applicable for multiple frequency keepers Purpose of test To demonstrate the stability of the control changes when entering into frequency keeping mode. This allows accurate steady state and dynamic frequency control modelling. The testing of the generator control equipment must verify that the generator can meet the performance requirements defined in the Procurement Plan. The monitoring equipment and response rate of the generator must also meet the Code requirements Test outcome If governor control is used for frequency keeping, the asset owner will be required to provide: a block diagram showing the verified (through testing) mathematical representation (control block diagram) of the frequency keeping control system. This includes any linear, nonlinear and discontinuous control blocks a parameter list showing gains, time constants, and other settings

14 14 PDF Created on: 01/05/17 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets Generator Tests Tests for Equipment Covered by Ancillary Service Contracts specifically applicable to the block diagram above results consisting of step responses and/or frequency response, as electronic data, of the frequency keeping control system to verify: the tuning and stability of the standard control system the stability of the generator/frequency keeping system when responding to small deviation in frequency, until the required drop/increase in generation is seen (this also demonstrates the minimum requirement for the generator/frequency keeping system to be able to ramp down/up 10MW per minute) the stability of the generator/frequency keeping system when responding to the other polarity of a small deviation in frequency, until the required drop/increase in generation is seen (once again, demonstrating the minimum requirement for the generator/frequency keeping system to be able to ramp in the opposite direction by 10MW per minute) a description of the frequency keeping control functionality, including the mode of operation available and when each mode is utilised. Any functionality that is not utilised should be clearly noted as such. If a method other than governor control is used for frequency keeping, the asset owner will be required to provide a verified model or description of how the frequency keeping is performed Tests that will achieve required outcome Example tests can be found in the appendix (Guide for testing): 5.7 Frequency Keeping Example injection curves Definition The provision of equipment that enables an automatic reduction in the level of power injection into the power system to arrest an unplanned rise in system frequency Application Generators can provide over-frequency arming Purpose of test The system operator needs to ensure the integrity of the over-frequency Ancillary Service provision by issuing requirements to service providers for assessing the Reserve Capability of their assets. The reason for testing reserve capability is to allow the System operator to model and manage the total system reserve in the market. The relay equipment must be maintained in accordance with good industry practice so that it can provide over-frequency reserve in accordance with the ancillary contract Test Outcome The test must verify the following:

15 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Generator Tests Tests for Equipment Covered by Ancillary Service Contracts 15 The arming signal arms the equipment The equipment operates correctly for simulated required frequency Trip circuitry is correctly connected. Indication of over-frequency arming is received by the Transpower SCADA The test should verify that the generator trips at the specified over-frequency and should demonstrate the time delays in the relay and breaker tripping. The test should also support any other contractual conditions Testing/ Information Frequency Testing requirements are defined in the Procurement Plan Definition The provision of interruptible load, partially loaded spinning reserve and/or tail water depressed (TWD) reserve (in each case as either fast instantaneous reserve or sustained instantaneous reserve) available to counter an under frequency excursion arising from an event. The total response expected will be fast enough and in a quantity sufficient to arrest the fall in frequency (fast instantaneous reserve), and assist in the recovery of frequency (sustained instantaneous reserve) Application Both generator and distributors can provide instantaneous reserve. Testing of the ancillary service is required by asset owners who enter into ancillary service contracts to provide instantaneous reserves. The minimum testing requirements are stipulated within the ancillary services contract Purpose of test The system operator needs to ensure the integrity of the instantaneous-reserve ancillary-service provision by issuing requirements to service providers for assessing the reserve capability of their assets. This is a proactive measure to provide the system operator with confidence that adequate reserve will be available in case of an under-frequency event. The reason for testing reserve capability is to allow the system operator to model and manage the total system reserve in the market. Testing provides the system operator with verification of the FIR/SIR capability of the generator and distributor Test/ Information Requirement Testing/ Information Frequency For TWD and loaded spinning reserve, the asset owner is required to provide results in response to the standard under-frequency curve, as electronic tabular data, of the governor or frequency control device. Note that reserve capability testing is separate to other industry requirements of ongoing monitoring to record pre/post- event data. Testing requirements are defined in the Procurement Plan Tests that will achieve required outcome Examples of tests can be found in the appendix (Guide for testing): 5.8 Instantaneous Reserve - Generator FIR/SIR capability

16 16 PDF Created on: 01/05/17 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets Generator Tests Tests for Equipment Covered by Ancillary Service Contracts Definition Reactive power injection or absorption capability of assets and other reactive power resources, provided to maintain voltage at a point of connection to the grid, with the objective of avoiding cascade failure and maintaining voltage fluctuations as outlined in Part 7 of the Code Application Voltage support can be provided by both generators and Grid Owner equipment. Testing of the ancillary service is required by asset owners who enter into ancillary service contracts to provide voltage support. The minimum testing requirements are stipulated within the ancillary services contract Purpose of test As stipulated in the ancillary services contract, testing is required to determine if the service meets the performance standards. The system operator needs to ensure the integrity of the voltage-support ancillary-service provision by issuing requirements to service providers for assessing the voltage support capability of their assets. Generators The required outcome of Exciter/AVR or voltage control testing is to provide the system operator with a verified mathematical model that describes the steady state and dynamic behaviour of the equipment. An accurate representation allows the system operator to model interactions with the system and other generating stations, when subjected to disturbances on the system, and thereby control the voltage stability of the system. Static VAr Compensator The outcome of static var compensator testing is to: provide the system operator with a mathematical model that describes the steady-state and dynamic behaviour of the SVC confirm the expected response to disturbances verify the integrity of the SVC control and protection systems Capacitor and Reactors Manually Controlled The outcome of capacitor and reactor testing is to verify their parameters for modelling purposes. AVR Controlled Capacitors/Reactors and Reactive Power Control The outcome is to check the operating thresholds and time delays of the capacitor switching operation. Synchronous Compensator The required outcome of synchronous compensator testing is to provide the system operator with a mathematical model that describes the equipment s steady state and dynamic behaviour. A model of the compensator is fundamental to any dynamic stability studies as well as load flow and fault studies. The standard 2-axes model is used, which is well documented in standards and literature Test/ Information The tests must verify the following:

17 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Generator Tests Tests for Equipment Covered by Ancillary Service Contracts 17 Requirement Static VAr Compensator A block diagram showing the mathematical model of the SVC. A parameter list showing the gains, time constants, limiters and other settings applicable to the above block diagram Detailed functional description of all the components of an SVC and how they interact in all modes of control. Test results from the step response tests (isolated or online operation), and the fault recovery AC disturbance response as electronic tabular data files, in order to verify the tuning and stability of the SVC. Capacitor/Reactors Tabular data Setting records Functional checks Synchronous Condenser The synchronous condenser parameter output tests are required to produce: characteristic curves which include a: Capability diagram open & short circuit curves V-curve zero power factor curve unbalanced load-time curve machine reactances machine time constants saturation data The tests are required to produce the following in relation to exciter/avr components of the synchronous condenser output: A block diagram showing the mathematical representation of the particular model of AVR and exciter installed on the synchronous condenser. Detailed functional description of the excitation system including all accessory functions: Load compensator, Under-excitation limiter, Over-excitation limiter, Voltage frequency limiter, P/Q limiter, Power system stabiliser. All modes of control should also be described, e.g. voltage control, power factor control, etc. A parameter list showing gains, time constants, and other settings applicable to the block diagram above. Commissioning and test results consisting of step responses (isolated

18 18 PDF Created on: 01/05/17 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets Generator Tests Tests for Equipment Covered by Ancillary Service Contracts operation), as electronic data, to verify the tuning and stability of the exciter Testing/ Information Frequency Testing requirements are defined in the Procurement Plan Tests that will achieve required outcome Appropriate tests can be found in the appendix (Guide for testing): Synchronous Machine Exciter Block Diagrams/Models Asynchronous Machine Voltage Control Block Diagrams/Models Static VAr Compensators Capacitors/Reactors Synchronous Compensators Definition Equipment that is made available to enable generation units isolated from a grid to be livened and connected to the grid, without any power being obtained from the grid Application Black starting generators are contracted as an ancillary service Purpose of test Testing/ Information Requirement The black start provider must be able to demonstrate the ability to recover from a total or partial shutdown of the transmission system. The black start capability is necessary to ensure the reliable operation of the national grid. The key objective of the black start test is to demonstrate that the processes, systems, and plant being tested are able to liven the grid if a black start is necessary. Testing requirements are defined in the Procurement Plan of the Code. The testing procedures specified in this document are generic tests to demonstrate black start capability. Site-specific tests are developed on a caseby-case basis and are agreed between the Asset Owner and the System Operator. The frequency of black start tests is also a condition of the individual black start contract. The following technical abilities need to be demonstrated during the testing: The ability to start up the main generation of the power station from shutdown in agreed timescales without power being obtained from the grid. The capability to energise part of the transmission grid system within agreed timescales following instruction from Transpower. The capability to accept instantaneous loading of demand blocks and controlling frequency and voltage levels within acceptable limits during the block loading process (under these conditions, frequency will be within the range 47 to 52 Hz); The reactive capability to charge the immediate transmission grid system. This capability will depend on the test system configuration.

19 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Generator Tests Tests for Equipment Covered by Ancillary Service Contracts Baseline Tests Each item of black start equipment is tested to prove that they can start without obtaining power from the grid.

20 20 PDF Created on: 01/05/17 Grid Owner Tests Grid Owner Doc File Name: GL-EA-010_Companion Guide for Testing of Assets 3 GRID OWNER TESTS 3.1 GRID OWNER Purpose This Section outlines the grid owner tests required to verify the steady state and dynamic performance of the grid owner assets. CONTENTS Transformers Transmission Lines Reactive Capability SVC Capacitor/Reactor and Reactive Power Control Systems Synchronous Compensators AVR/Exciter Systems HVDC Link Frequency Control and Protection Protection Systems AUFLS Profiles and Trip Settings Content This section describes the test/information requirements for grid owner transformers Application This section applies to all transformers owned by the grid owner. Routing testing applies to all transformers with on-load tap-changers that operate to a voltage set point in automatic voltage control Purpose of test The primary purpose of obtaining transformer data is to assess the ability of transformer units to maintain point of supply voltage and reactive power capability within the applicable limits. The transformer should be tested during commissioning, when modifying plant or associated equipment, or has been in service for an extended period and require routine testing. This is likely to be the case subsequent to the following events: where the transformer equipment has significantly changed (including tap changers, transformer bushings, earthing resistors and reactors, cooling systems) following any maintenance or servicing that involves major components of the transformer where the transformer control equipment differs from the original specification routinely with a test interval as detailed in The Routine Testing appendix in Part 8 of the Code Provided that nameplate and manufacturer information is available, no further testing of the construction parameters will be required (I.E impedances).

21 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Grid Owner Tests Grid Owner Test outcome The testing will result in verification of the control system of on load tap changers (that automatically operate to a voltage set point) at a controlled node of the grid. This testing includes: voltage setpoints operating deadband response times ACS Reference This information is required in the ACS Test that will achieve required outcome Appropriate tests can be found in the appendix (Guide for testing) Routine Tests: Tap Changers Routine Testing Commissioning Tests: General Transformer Data - Commissioning Resistance and Reactance - Commissioning Content This section details the basic technical requirements for transmission lines testing Application This section applies to transmission lines owned by the grid owner Purpose of test Data to be provided by way of ACS when asset is first built or when changes are made which affect the electrical characteristics of the asset. Electrical parameters may be determined from manufacturer s data, the asset owner s calculations, simulations and commissioning test data. The system operator may require that a physical test be conducted to determine the capacitance of a line. The primary purpose of obtaining and submitting transmission line data is to enable the system operator to maintain system security, particularly with respect to security planning and offload times Test outcome The asset owner is required to provide suitable models together with the required parameters to model power flows and transient stability ACS Reference The test/information requirements for transmission lines are as per the relevant section of the grid owner ACS Tests that will achieve required outcome Appropriate tests can be found in the appendix (Guide for testing): 5.9 Transmission Line

22 22 PDF Created on: 01/05/17 Grid Owner Tests Grid Owner Doc File Name: GL-EA-010_Companion Guide for Testing of Assets Content This section details the basic technical requirements for the grid owner with respect to static var compensator (SVC) equipment Application This section applies to the grid owner for all SVC equipment. The SVC and associated equipment should be tested during commissioning, when modifying plant or associated equipment, or has been in service for an extended period and requires routine testing. The routine testing requirements are set out in the appendix of Part 8 of the Code Purpose of test The SVC voltage response and control testing is required to allow accurate steady state and dynamic modelling, which allows secure and stable operation of the national grid. The purpose of SVC testing is to: provide a mathematical model that describes the steady-state and dynamic behaviour of the SVC allow the SVC interaction with the system when subjected to disturbances in the system to be modelled. This will assist voltage stability verify the integrity of the SVC control and protection systems Test outcome The test/information requirements of the SVC output are: a block diagram showing the verified (through testing) mathematical model of the SVC, including all linear, non-linear and discontinuous control blocks a parameter list showing the gains, time constants, limiters, and other settings applicable to the above block diagram a detailed functional description of all the components of an SVC and how they interact in all modes of control test results from step response tests (isolated or online operation), and the fault recovery AC disturbance response as electronic tabular data files, to verify the tuning and stability of the SVC ACS Reference This information is required in the ACS Test that will achieve required outcome Appropriate tests can be found in the appendix (Guide for testing) : Static VAr Compensators Content This section details the basic technical requirements for the grid owner tests with respect to capacitors, reactors and reactive power control systems Application This section applies to the capacitors, reactors and reactive power control systems owned by the grid owner

23 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Grid Owner Tests Grid Owner 23 The capacitor/reactors, reactive power control systems, and associated equipment should be tested during commissioning, when modifying plant or associated equipment, or has been in service for an extended period and requires routine testing. The routine testing requirements are set out in the appendix in Part 8 of the Code Purpose of test The capacitor and reactor voltage-response and control testing is required to allow accurate steady state and dynamic modelling, which allows secure and stable operation of the national grid Test outcome The asset owner will be required to provide: tests to confirm the parameters of capacitors or reactors for modelling purposes tests to confirm the operating thresholds and time delays of the capacitor, reactor and/or reactive power controller switching operations that are controlled by an AVR an explanation of the modes of operation of the reactive power controller, and models demonstrating the controller and response This data is expected in electronic form so any graphs can be re-created. The data resolution for the reactive power control systems needs to be high enough to show any transient activity that occurs during switching ACS Reference This information is required in the ACS Test that will achieve required outcome Appropriate tests can be found in the appendix (Guide for testing): Capacitors/Reactors Content This section details the basic technical requirements for the grid owner tests with respect to synchronous compensators Application This section applies to synchronous compensators owned by the grid owner. The voltage control system/avr and exciter should be tested during commissioning, where the model and/or parameters have been changed, or where it has been in service for extended period and requires routine testing. This is likely to be the case: following any maintenance or servicing that involves major components of the excitation or AVR/voltage control system where the exciter or AVR/voltage control equipment has significantly changed where the exciter or AVR/voltage control equipment differs from the original specifications routinely with a test interval as detailed in the Routine Testing appendix in Part 8 of the Code Purpose of test The synchronous compensator voltage-response and control testing is required to allow accurate steady state and dynamic modelling. These models are integrated into a network wide model, which allows secure and stable operation

24 24 PDF Created on: 01/05/17 Grid Owner Tests Grid Owner Doc File Name: GL-EA-010_Companion Guide for Testing of Assets of the national grid. An accurate representation: demonstrates asset owner compliance with Part 8 of the Code and the relevant technical codes allows the system operator to model interaction of the asset with the grid and other generating stations when subjected to disturbances on the system. Such modelling assists with control of voltage stability Test outcome During Commissioning The synchronous condenser parameter output tests are required to produce: characteristic curves which include: capability diagram open & short circuit curves V-curve zero power factor curve unbalanced load-time curve machine reactances machine time constants saturation data During Commissioning, modification to plant or Routinely The asset owner is required to provide: a block diagram showing the verified (through testing) mathematical representation of the particular manufacturer s model of AVR/voltage control system and exciter that is controlling the unit. This includes all non-linear and discontinuous functions of the AVR (i.e. OEL, UEL, and PSS). See IEEE Std for more information. a detailed functional description of the excitation system including all accessory functions: Load compensator, Under-excitation limiter, Overexcitation limiter, Voltage frequency limiter, Power System Stabiliser. All modes of control should also be described, e.g. voltage control, MVAr control etc a parameter list showing gains, time constants, and other settings applicable to the block diagram above results consisting of step responses and/or voltage response, as electronic data, of the AVR or voltage control device to verify: the tuning and stability of the standard functionality of the control system the over excitation limit (OEL) of the control system the under excitation limit (UEL) of the control system any other discontinuous control block (i.e. deadband) Data resolution needs to be of adequate precision to identify any dynamic response from the governor or frequency control system. The measured data types are dependent on the model requirements/inputs, which ultimately need to mimic the results seen in the tests. The model should be constructed before testing so the measurement requirements are fully defined.

25 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Grid Owner Tests Grid Owner ACS Reference This information is required in the ACS Test that will achieve required outcome Appropriate tests can be found in the appendix (Guide for testing): Synchronous Machine Exciter Block Diagrams/Models Content This section details the basic technical requirements for the grid owner tests with respect to HVDC equipment Application The HVDC and associated equipment should be tested during commissioning, when modifying plant or associated equipment, or where it has been in service for extended period and require routine testing. This is likely to be the case: following any maintenance or servicing that involves major components of the HVDC and associated equipment where the HVDC and associated equipment has significantly changed where the HVDC control equipment differs from the original specifications routinely with a test interval as detailed in the Routine Testing appendix in Part 8 of the Code Purpose of test Tests on critical aspects of the HVDC are required for the purpose of ensuring the behaviour of the link can be accurately modelled. Therefore, HVDC tests are required to: provide a control system model that reflects the behaviour of the link in all possible operating conditions verify control functionality of main modulations verify the integrity of primary plant control and protection systems Test outcome The HVDC control testing will be required to produce: a block diagram showing the verified (through testing) mathematical representation of the HVDC. This includes all linear, non-linear and discontinuous control blocks inherent to HVDC control. a parameter list showing the gains, time constants, limiters and other settings applicable to the above block diagram a detailed functional description of all the main components of the HVDC and how they interact in all modes of control results from offline or online testing (wherever possible) of the HVDC for all the main modulation functions it performs ACS Reference This information is required in ACS Test that will achieve required outcome Appropriate tests can be found in the appendix (Guide for testing): 5.10 HVDC

26 26 PDF Created on: 01/05/17 Grid Owner Tests Grid Owner Doc File Name: GL-EA-010_Companion Guide for Testing of Assets Content This section describes the minimum recommended routine testing for general grid owner protection assets not already covered by previous requirements Application This section applies to the grid owner s assets at the grid interface Purpose of test The effectiveness and co-ordination of asset-owner protection systems are fundamental to the system operator s ability to plan to comply and comply with the PPOs. Testing of the protection system demonstrates grid owner compliance with all AOPO s and technical codes, as outlined in Part 8 of the Code, and provides the system operator and other asset owners with assurance that asset owners are co-operating to ensure protection is co-ordinated across the grid interface Test outcome Testing of protection systems is required to confirm: protection is co-ordinated across the grid interface accuracy of primary circuit parameters and integrity of the tripping circuit components at the grid interface protection settings are properly identified, applied and checked to meet the outcomes set out in the Code protection is coordinated with other asset owners at the grid interface protection remains coordinated, with other asset owners at the grid interface, after any modification and change at the grid interface ACS Reference The information is required in the ACS as a series of confirming questions (i.e. yes or no answers are only required) Test that will achieve required outcome Appropriate tests can be found in the appendix (Guide for testing): 5.7 Protection Systems Content This section details the basic technical requirements for the AUFLS equipment for which the grid owner is responsible Application This section applies to the grid owner, who is responsible for providing some AUFLS equipment. Testing is required after commissioning or modification of AUFLS equipment Purpose of test AUFLS are a critical factor in the system operator s assessment of reserve requirements to prevent cascade failure of the power system. Tests are therefore required to confirm: the AUFLS profiles, and the trip settings and reliability of the relays Test outcomes The tests are required to ensure the Code relating to AUFLS are met, demonstrated by:

27 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Grid Owner Tests Grid Owner 27 profile data 1 provided in an update of the ACS high speed test results (tabulated) of the AUFLS relay functionality, which includes step/ramp (frequency) test to demonstrate the guard, trigger and clearing time delays where df/dt relays are used, two frequency ramps should be injected to test that the relay discriminates to the correct rate of change of frequency ACS Reference The information is required in the ACS Tests that will achieve required outcome Appropriate tests can be found in the appendix (Guide for testing): 5.11 AUFLS 1 The percentage of total pre-event demand for two blocks of demand is required as per Part 8 of the Code. The profile information required by the ACS should outline the variability of the data according to time of day/season.

28 28 PDF Created on: 01/05/17 Distributor Tests Distributors Doc File Name: GL-EA-010_Companion Guide for Testing of Assets 4 DISTRIBUTOR TESTS 4.1 DISTRIBUTORS Purpose This part describes the routine tests that distributors are required to undertake on their assets. CONTENTS AUFLS Profiles and Trip Settings Protection Systems Distributor Load Characteristics Content This section describes the tests that are required to confirm functionality and compliance of AUFLS Application This section applies to all asset owners who offer AUFLS and should be read alongside the latest Technical Requirement Schedule (TRS) Purpose of test AUFLS is a critical factor in the system operator s assessment of reserve requirements to prevent cascade failure of the power system. Tests are required to meet obligations set out in the TRS, which include confirmation of: Test outcomes The tests should: Trip settings; Reliability 2 of the AUFLS scheme; and End-to-end operation times. Provide high-speed test results to demonstrate the AUFLS relay functionality, as well as the guard, trigger and clearing time delays. Where df/dt relays are used, demonstration of operation to the correct rate of change of frequency Verify manufacturer and custom relay logic, DC control logic to confirm operation is in accordance with relay and instrumentation diagrams and operating notes Compliance The information is required in a Compliance Report within 3 months of testing. 2 Reliability of a protection scheme is rated in two aspects, dependability and security. Dependability is defined as the degree of certainty that a relay or relay system will operate correctly (IEEE C37.2). Security relates to the degree of certainty that a relay or relay system will not operate correctly (IEEE C37.2).

29 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Distributor Tests Distributors 29 Report Tests that will achieve required outcome An example of a Compliance Report is available on the Transpower website document reference DT-EA-601 Extended Reserve Example TRS Compliance Report Appropriate tests can be found in the appendix (Guide for testing): 5.11 AUFLS Content This section describes the minimum recommended routine testing for distributor protection assets not already covered by previous requirements Application This section applies to the distributor s assets at the grid interface Purpose of test The effectiveness and co-ordination of asset-owner protection systems are fundamental to the system operator s ability to plan to comply and comply with the PPOs. Testing of the protection system demonstrates grid owner compliance with all AOPO s and technical codes, as outlined in Part 8 of the Code, and provides the system operator and other asset owners with assurance that asset owners are cooperating to ensure protection is co-ordinated across the grid interface Test outcomes Testing of protection systems is required to confirm: protection is co-ordinated across the grid interface accuracy of primary circuit parameters and integrity of the tripping circuit components at the grid interface protection settings are properly identified, applied and checked to meet the outcomes set out in the Code protection is coordinated with other asset owners at the grid interface protection remains coordinated, with other asset owners at the grid interface, after any modification and change at the grid interface The testing plan and protection settings should be co-ordinate with the grid/asset owner protection team before testing is commenced. Once both parties are satisfied with the protection co-ordination, then the assurance can come through the ACS ACS Reference The information is required in the ACS as a series of confirming questions (i.e. yes or no answers are only required) Tests that will achieve required outcome Appropriate tests can be found in the appendix (Guide for testing): 5.7 Protection Systems

30 30 PDF Created on: 01/05/17 Distributor Tests Distributors Doc File Name: GL-EA-010_Companion Guide for Testing of Assets Content This section describes the information required to determine distributor load characteristics Application Load characteristic data is required in ACS. It needs updating whenever significant changes occur due to commissioning or modification to the load, or re-configuration of the distribution network that will alter the load characteristics at the GXP Purpose of information Information outcomes Load characteristic information is required to assist in producing an accurate representation of the load and its response to fluctuations in voltage and frequency. Notification of embedded generation above 1 MW is also required to determine if the generators information is present within ACS. Detailed knowledge of loads improves modelling and makes use of actual system capability rather than relying on conservative estimates. The distributors are required to provide the proportion of their distribution load which is static and the proportion which is dynamic (i.e. motor driven) for both summer and winter periods ACS Reference The proportion of static load to motor load is to be submitted via ACS Relevant Standards IEC : 1985, Rotating Electrical Machines Part 4: Methods For Determining Synchronous Machine Quantities From Tests. IEEE Std , IEEE Guide: Test Procedures for Synchronous Machines: Part II Test Procedures and Parameter Determination for Dynamic analysis. IEEE Std , IEEE Standard Test Procedure for Polyphase Induction Motors and Generators.

31 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Distributor Tests Tests for Equipment Covered by Ancillary Contracts TESTS FOR EQUIPMENT COVERED BY ANCILLARY CONTRACTS Purpose This part describes the Distributor tests used to provide sufficient information to verify the following: FIR/SIR capability IL functionality CONTENTS Instantaneous Reserve Definition The provision of interruptible load, partially loaded spinning reserve and/or tail water depressed reserve (in each case as either fast instantaneous reserve or sustained instantaneous reserve) available to counter an under frequency excursion arising from an event. The total response expected will be fast enough and in a quantity sufficient to arrest the fall in frequency (fast instantaneous reserve), and assist in the recovery of frequency (sustained instantaneous reserve) Application Instantaneous reserve can be provided by both generators and distributors who enter into ancillary service contracts. The minimum testing requirements are stipulated within the ancillary services contract Purpose of test As stipulated in the ancillary services contract, testing is required to determine if the service meets the performance standards. The system operator needs to ensure the integrity of the instantaneous-reserve ancillary-service provision by issuing requirements to service providers for assessing the reserve capability of their assets. This is a proactive measure to provide the system operator with confidence that adequate reserve will be available in case of an under-frequency event. The reason for testing reserve capability is to allow the system operator to model and manage the total system reserve in the market. Testing provides the system operator with verification of the FIR/SIR capability of the Generator & Distributor, in response to a standard under-frequency curve used as a proxy for underfrequency events Test Outcomes For interruptible load, the asset owner is expected to provide step response and/or frequency response, of the relay and circuit breaker response, to demonstrate the time delay of the associated equipment. Note that reserve capability testing is separate to other industry requirements of ongoing monitoring to record pre/post- event data.

32 32 PDF Created on: 01/05/17 Distributor Tests Tests for Equipment Covered by Ancillary Contracts Doc File Name: GL-EA-010_Companion Guide for Testing of Assets Testing/ Information Frequency Testing requirements are defined in the Procurement Plan Tests that will achieve required outcome Appropriate tests can be found in the appendix (Guide for testing): 5.12 Distributor Reserve Capability

33 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory 33 5 GUIDE FOR TESTING EXAMPLES AND THEORY 5.1 OVERVIEW This section provides specific details of the methods for testing, and some examples of tests that asset owner s may use as a basis for developing testing plans. An example compliance report that may be requested by the system operator from asset owners is attached at the end of this section. CONTENTS Purpose Generating Unit Parameters General Machine Parameters Synchronous Machine Characteristic Curves Synchronous Machine Impedances Synchronous Machine Time Constants Synchronous Machine Saturation Data Asynchronous Machine Impedances Transformers General Transformer Data - Commissioning Resistance and Reactance - Commissioning Tap Changers Routine Testing Generator Frequency Performance General Frequency Performance Data Generating/Synchronous-compensating Unit Exciter/AVR and Voltage Control Synchronous Machine Exciter Block Diagrams/Models Asynchronous Machine Voltage Control Block Diagrams/Models Static VAr Compensators Capacitors/Reactors Synchronous Compensators Generating Unit Governor/Turbine and Frequency Control Governor Block Diagrams/Models Governor Stability Example governor frequency injection curves Frequency Keeping Example injection curves Instantaneous Reserve - Generator FIR/SIR capability Transmission Line HVDC HVDC tests HVDC - commissioning only AUFLS General Requirements Example Relay and Instrument Diagram Example DC Control and Relay Logic Diagram Example Settings and Trip Equations Conformance Tests Graphical Representation of Tests Compliance Report Template Distributor Reserve Capability... 59

34 34 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory 5.2 GENERATING UNIT PARAMETERS Rated MW MCO Auxiliary Power (Active and Reactive Auxiliary Load) Generating unit Inertia Constant Short Circuit Ratio (Synchronous Machines only) The rated (or nominal) active power of the machine is defined as the machine s apparent power (MVA base) times the rated power factor. The MCO is the maximum continuous active power output of the machine as measured at the generating unit terminals (excluding auxiliary losses). This may differ from the Rated MW due to turbine capability (higher or lower), or operating restrictions (lower) like fuel, hydraulic, or equipment constraints. Auxiliary power is tested by direct measurement of auxiliary load MW and MVAr at rated power (or MCO if different from rated MW) of the generating unit. Whether or not the auxiliary load trips with the generating unit should also be stated. Where the auxiliary load is less than 1 MVA, it can be ignored and negligible can be entered in the ACS. In general, auxiliary losses are only usually significant in thermal (steam, gas, CCGT, geothermal) power stations. Distinction should be made between the maximum auxiliary load in the period 1 minute after a trip / shutdown and the maximum auxiliary load for starting the generator. The generating unit s inertia constant can either be obtained from the manufacturer or by monitoring: By Calculation The manufacturer typically provides the generating unit & turbine moment of inertia as a WR2 or GD2 value (kg.m2) which is converted to a time constant (sec) by: H = x 10-9 (WR2) nrpm2 / Sbase where: nrpm = nominal speed (rpm) Sbase = MVA base If the moment of inertia is provided in lb.ft2, the inertia constant is defined as: H = 2.31 x (WR2) nrpm2 / Sbase The inertia constant formula is divided by four if the GD2 factor is used in place of the WR2 factor. By Test The inertia can be calculated from the slope of the initial (linear) increase in speed after a load rejection. H = 0.5 * P / ( / t) Where and P are in pu (on frequency and machine MVA base respectively). Alternatively in terms of mechanical starting time, the inertia is calculated as follows: H = Tm / 2 * pf, Where the power factor (pf) is calculated from the full load output (not necessarily the same as PNominal) in MW divided by the machine MVA base. This method usually results in a higher value than that calculated effect data due to the influence of from the flywheel friction and windage. The short circuit ratio is obtained from the open circuit and short circuit curves; it is the ratio of the field current at no-load voltage (IFNL) divided by the field current corresponding to base armature current on the short circuit saturation curve (IFSI). SCR = IFNL / IFSI Generator Capability Curve Open circuit Curve The generator capability curve shows the reactive capability of the machine and should include any restrictions on the real or reactive power range like under/over excitation limits, stability limits, etc. All generating units required to provide reactive support should have an MVAr range that meets the requirements of the Code. Curves for minimum and maximum voltage range are required in addition to those for operation at 1 pu. This is tested while connected to the system, but it may be somewhat restricted by grid voltage constraints if the plant is older and does not have on-load tap changers on the generating unit transformers. Where plant has a generator transformer featuring a suitable on-load tap-changer, it should be possible to test the generator over its full reactive power range. Parameters supplied by manufacturers are also acceptable if they are the most recent and most accurate data available. The open circuit curve plots the no-load terminal voltage generally from 0 to 1.2 pu of the rated voltage of the machine, versus the machine excitation (field) current. Note that if the allowable maximum voltage is less than 1.2 pu. then extrapolation of the curve to 1.2 will be required. Extrapolation is used to complete the lower part of the curve and produce the air-gap line. The manufacturer s information/test results are acceptable for plant that has not been rewound, modified, or re-rated.

35 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory 35 Short circuit Curve V Curve The short circuit curve plots the armature current (with the terminals short-circuited) versus the machine excitation (field) current. The manufacturer s information/test results are acceptable for plant that has not been rewound, modified, or re-rated. The generating unit V-curve is a plot of the terminal (armature) current versus the generating unit field voltage. It is produced by setting the MW output to 0 pu. and recording the field voltage and terminal current as the excitation is increased from leading power factor to lagging power factor. The test is repeated for MW = 0.25, 0.50, 0.75, and 1.0 pu. The reason for these tests is to confirm the steady state operation of the machine (i.e. verify Xd and Xq). Zero Power Factor Curve The zero power-factor saturation curve is a plot of the terminal voltage against field current for a constant armature current. It can be used to obtain the Poitier reactance. This is normally part of the manufacturing documentation, and a one off test would only be required if this information is unavailable. IEEE Std , Part II, section gives a method of testing this, involving the use of a 2nd machine. Unbalanced Load-Time Curve Relevant Standards Manufacturer documentation and factory tests normally provide the effect of unbalanced load on unbalanced stator current. Standard ANSI C specifies the short-circuit generator capabilities, short-time current and continuous-current unbalance requirements. IEEE Std , IEEE Guide for Operation and Maintenance of Hydro-Generators. IEEE Std , IEEE Guide: Test Procedures For Synchronous Machines. ANSI C (Reaff 1989), Requirements for Salient Pole Synchronous Generators and Generator/Motors for Hydraulic Turbine Applications. Xd, Xq, Xd, Xq, Xd, Xq, Xl, X2, X0 Use of Reactive Power Load Rejections to obtain parameters Earthing resistance (Re) & reactance (X e) Relevant Standards These parameters are all well defined and documented by the applicable standards and literature. Many of these parameters can be determined by a number of different tests and the generator asset owner can choose an appropriate method, as long as it is based on an accepted standard, or published document. Parameters supplied by manufacturers are also acceptable if they are the most recent and most accurate data available. Several papers describe how machine parameters can be obtained using reactive power load-rejection tests (while the machine is under-excited, i.e. absorbing MVAr from the system). This method can be used to obtain the direct axis reactances and time constants. To obtain the quadrature-axis reactances and time constants requires finding the loading point (MW and MVAr) where armature current lines up with the quadrature axis (when the power factor = rotor power angle) and then using the same method as for the direct axis values. Refer to: Derivation of Synchronous Machine Parameters from tests. F P de Mello & J R Ribeiro, IEEE Transactions on Power Apparatus and Systems, Vol PAS-96, No 4, July/August Identification of Synchronous Machine Parameters Using Load Rejection Test Data. E da Costa Bortoni, J A Jardini, IEEE Transactions on Energy Conversion, Vol 17, No.2, June These tests require that the generating set s field current is measured, and that the AVR is switched to manual. Curve fitting techniques will be required to refine the parameters. These methods have previously been used in NZ to derive parameters for generating units. A range of alternative tests is given in the applicable standards: IEC : 1985 and IEEE Std The system operator requires the unsaturated machine reactances, defined by IEC as the rated (armature) current value of the quantity, except the synchronous reactance that are not defined as saturated. The unsaturated direct axis synchronous reactance Xd can also be readily obtained from the open & short circuit curves by: Xd = IFSI / IFG Where: IFSI is the field current corresponding to base armature current on the short circuit saturation curve, IFG is the field current corresponding to the rated (base) voltage on the air-gap line from the open circuit curve. The generating unit V-curves can also be used to determine (by a trial & error process) values for Xd, Xq and SE. Synchronous machines are usually earthed via a resistor or a distribution transformer with a resistor connected across the secondary winding. In the latter case, the resistance and reactance should be reflected to the primary side of the transformer. Usual test methods apply. IEC : 1985, Rotating Electrical Machines Part 4: Methods For Determining Synchronous Machine Quantities From Tests. IEEE Std , IEEE Guide: Test Procedures for Synchronous Machines: Part II Test Procedures and Parameter Determination for Dynamic analysis.

36 36 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory Open Circuit Time Constants Tdo, Tqo (cylindrical machines only), Tdo, Tqo The system operator requires the open circuit time constants (defined by IEC as the time required for the slowly changing component of the open-circuit armature voltage, which is due to the direct flux following a sudden change in operating conditions), to decrease to 1/ of its initial value. Testing for these parameters is as per the section above. Open Circuit Saturation Curve The open circuit saturation curve yields the machine saturation parameters S 1.0 and S 1.2. The method of calculating these parameters is well documented in the literature and textbooks and are defined as: S 1.0 = (I B-I A)/I A Where: I A is the excitation current required to produce 1.0 pu terminal voltage on the air-gap line, and I B is the excitation current required to produce 1.0 pu terminal voltage on the actual curve. Likewise, to calculate S 1.2, I A and I B are taken at 1.2 pu terminal voltage. Alternatively if the values at 1.2 pu terminal voltage are not available (or cannot be achieved) they can be calculated by fitting an exponential curve (a.v term b ) to data points around the rated voltage, solving for a and b, which can then be used to calculate S 1.2 at 1.2 pu terminal voltage. R 1, X 1, X m, R 2, X 2 The tests for obtaining these parameters are well documented in the literature and in particular the IEEE standard The no-load test can be used to obtain the self-reactance of the stator (summation of X 1 and X m). The d-c test can be used to obtain the stator resistance (R 1) The blocked-rotor test can be used to obtain the parameters R 2, and X 2, given a wound rotor type or the class type of a squirrel cage rotor at rated frequency. Relevant Standards IEEE Std , IEEE Standard Test Procedure for Polyphase Induction Motors and Generators.

37 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory TRANSFORMERS General Parameters The following parameters are required. Parameters may be found on the transformer nameplate, manufacturer documentation, and/or in test reports. Nominal voltage ratio Number of windings per phase Rating HV/LV (2-winding transformers) Rating HV/MV/LV (3-winding transformers) Bushing Nominal, Emergency Overload and Fault Ratings Vector Group Core Losses Magnetising Current B-H Curve` Construction Type Resistance and Reactance These parameters should all be available from the manufacturer and commissioning test reports. The values should all be referenced to the high voltage side MVA base. Positive Sequence Impedance Data (2 and 3 winding transformers) Zero Sequence Impedance Data (2 winding and 3 winding transformers) If the transformer has never been tested or the records are unavailable, the transformer will require testing (using the standard transformer test methods) to determine these values. Type and Position The type is either: On-load (manual or automatic) Off-load Fixed The step size is the % change of nominal voltage per step. Some transformers have multiple step sizes, if this is the case, it should be clearly stated. The tap range is the % change (of nominal voltage) from maximum (highest voltage) to minimum (lowest voltage) The nominal tap position is: Control System For off-load tap changers, the actual voltage and the tap number. For on-load tap changers, the nominal voltage and the tap number. Note that the numbering sequence assumed is that the lowest tap number corresponds to the lowest voltage (ratio). If the sequence is reversed, it should be clearly stated. These parameters can all be determined by inspection of nameplate or manufacturer / commissioning test reports. If information is not available from the manufacturer or commissioning tests then physical testing will be required. Voltage regulating relays of on-load tap changers that operate to a voltage setpoint are required to be

38 38 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory Operation tested for grid-connected transformers to verify the following: Voltage setpoint Operating deadband Response time The Voltage regulating relays of on-load tap changers are to be verified by: injection testing; or according to the individual asset owner s standard equipment test procedures 5.4 GENERATOR FREQUENCY PERFORMANCE Under Frequency Settings Over Frequency Settings Frequency Performance Curve Under frequency relay trip settings and time delays are verified by: injection testing; or according to the individual asset owner s standard protection equipment test procedures Over frequency tests shall be verified by: conducting un-synchronised turbine over-speed tests if this is the nature of the over frequency trip; or according to the individual asset owner s standard protection equipment test procedures The frequency performance curve will be supplied by the manufacturer where the power output can fall with falling frequency, compounding an under frequency event (applicable to gas turbines or combined cycle plant in particular). High speed monitoring should be used to validate this curve as system frequency events allow. 5.5 GENERATING/SYNCHRONOUS-COMPENSATING UNIT EXCITER/AVR AND VOLTAGE CONTROL Exciter Type (Block diagram) There are many different types of excitation systems in use, and consequently there are a large number of possible mathematical models to describe the dynamic behaviour of an excitation system. For new equipment, the manufacturer will be able to provide a suitable model for dynamic studies together with the required parameters. These need to be tested and verified (and if necessary modified) at commissioning time. Alternatively, a mathematical model can be selected based on its generic type: DC, AC or ST (Static), and inspection of the schematics and other manufacturers documentation. An appropriate model can generally be selected from the following standard types (as defined in IEEE Std ): Type DC1A DC commutator exciter. Type DC2A DC commutator exciter with bus fed regulator. Type DC3A DC commutator exciter with non-continuously acting regulators. Type AC1A Alternator-rectifier excitation system with non-controlled rectifiers and feedback from exciter field current. Type AC2A High initial response alternator rectifier excitation system with non-controlled rectifiers and

39 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory 39 Settings/ Parameters feedback from exciter field current. Type AC3A Alternator-rectifier exciter with alternator field current limiter. Type AC4A Alternator supplied controlled-rectifier exciter. Type AC5A Simplified rotating rectifier excitation system. Type AC6A Alternator-rectifier excitation system with non-controlled rectifiers and system supplied electronic voltage regulator. Type ST1A Potential-source controlled-rectifier exciter. Type ST2A Compound-source rectifier exciter. Type ST3A Potential or compound-source controlled-rectifier exciter with field voltage control loop. Additional functionality for individual manufacturers may be required. Where additional components such as over and under excitation limiters are fitted, appropriate block diagrams should also be provided for these components to show where they connect into the excitation model complete with a description of how and when they operate. Similarly, any standard functionality that is not used should be listed along with a note to that effect. Associated with the excitation system model is a parameter list that contains the tuning settings, gains, and time constants that control the response of the excitation system. For modern excitation systems with digital AVRs, many of the required parameters can be obtained directly, or with scaling, from the settings documentation supplied by the manufacturer. For older plant which is being re-tested or which has never been tested, a trial and error approach may be needed, using parameter identification and curve fitting techniques (this has been used in the past for deriving models for generating units in the NZ system). The parameters can be verified by comparing simulated responses with test results. Tests that can be carried out are: Terminal voltage step response tests (with the machine running at no-load isolated from the system, an example of this test can be seen in Figure 1). Frequency response tests (both isolated and connected to the grid). MVAr load rejection tests (high leading MVAr, and high lagging MVAr). Exciter Stability The system operator criteria for testing the stability of the model are to model the generating unit and exciter isolated from the system and to apply a step change to the exciter s voltage reference. The transient response of the generating unit terminal voltage should be stable and well damped. Figure 3 of IEEE Std shows the classical ideal control system response with 1.5 cycles to reach settling band and approximately 15% overshoot on the first oscillation. The response can be verified with a tested result. Other methods that can be performed (by test or simulation) to verify the stability of the excitation system are: Open loop frequency response Bode plots (used to obtain the gain and phase margins). Gain margin should typically be 6 db or more, and phase margin should typically be 40 or more. Closed loop frequency response Bode plots (used to obtain the peak amplitude response and the bandwidth). Example injection test curve To confirm general stability of the AVR/voltage control system, a ±5% deviation on voltage set point is typically used with the machine running at no-load, isolated from the system (open circuit conditions). This is one example of the tests that could be used to characterise the AVR/Voltage control system. An example test injection curve of the positive step can be seen below in Figure 1:

40 Voltage (pu) 40 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory Open circuit voltage reference injection test Time (s) Figure 1: Example open circuit voltage injection test. Testing is not limited to this one example. Extra testing is required to demonstrate the response to each discontinuous control block (OEL,UEL,PSS etc). These tests are specific to the type of AVR / voltage control system being used. It is recommended that the model is constructed before the testing plan is finalised. This gives much greater visibility into what testing is required, what data is required to measure and what the response should look like. Relevant Standards IEEE Std : IEEE Guide for Identification, Testing, and Evaluation of the Dynamic Performance of Excitation Control Systems. IEEE Std : IEEE Recommended Practice for Excitation System Models for Power System Stability Studies. IEC : Rotating Electrical Machines - Excitation Systems for Synchronous Machines Chapter 1, Definitions. Specifically for Synchronous compensators: IEC (01-Jan-1985), Rotating electrical machines. Part 4: Methods for determining synchronous machine quantities from tests. IEC Amd 1 (26-Apr-1995), Amendment 1 - Rotating electrical machines. Part 4: Methods for determining synchronous machine quantities from tests. Functional and Block Diagram Settings/ Parameters Reactive Power Compensation Relevant Standards Reactive power consumption/production for induction machines can be achieved by either reactive power setpoint or power factor setpoint. The manufacturer usually supplies the block diagram of the type of control. If power factor setpoint is used, the adjustment of the setpoint according to the grid voltage level should be described. Clearly state the proposed control mode. For adjustable parameters, the range, deadband and rate should be stated and proposed settings supplied. Total reactive power (MVAr) of the compensation capacitor bank and step size for each step, or number of steps and capacitor size (MVAr) for uniform steps, should be supplied from the manufacturer's information. IEEE Std : IEEE Standard Test Procedure for Polyphase Induction Motors and Generators.

41 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory 41 General Tests This section details the basic technical requirements for the asset owner with respect to SVC equipment. The manufacturer or commissioning test reports should be able to supply suitable models together with the required parameters. Otherwise, physical testing will be needed to identify the required models and parameters. Routine tests are required as follows: Steady-state and dynamic stability step-response (isolated or online operation) AC disturbance performance (fault recovery) SVC equipment integrity checks should be done by performing primary and/or secondary injections for verifying the following: Relevant Standards Input signals Controls, protection and indications of correct output Note: All SVC tests are to be performed to international standards. IEEE Std (01-May-2000), IEEE Guide for the Functional Specification of Transmission Static Var Compensators IEC Std (27-Mar-2003) Power electronics for electrical transmission and distribution systems - Testing of thyristor valves for static VAR compensators General Tests This section details the basic technical requirements for the asset owner tests with respect to capacitors and reactors. Tests undertaken at commissioning or are part of factory testing include: Capacitance measurement Impedance measurement DC winding resistance These tests will be undertaken according to IEC for capacitors and IEC for reactors. Tests undertaken for capacitors or capacitor/filter banks as part of routine maintenance include: Capacitance measurement Tests undertaken for automatic voltage regulation schemes such as automatic capacitor switching, reactive power control (RPC) or DC control winding reactance include: Operating threshold Time delay If information is not available from the manufacturer or commissioning then physical testing will be required. Relevant Standards IEC (17-Oct-1997), Shunt capacitors for a.c. power systems having a rated voltage above 1000 V - Part 1: General performance, testing and rating - Safety requirements - Guide for installation and operation IEC (15-May-1988) Reactors

42 42 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory Machine Tests Reactive Power capability Heat run test at full reactive power output This test will be undertaken according to the contract specification Transpower has with the relevant customer. Machine Reactances For machine reactances factory tests undertaken will be Open circuit and short circuit tests This test will be undertaken according to IEC Machine Time constants For machine time constants, factory tests undertaken will be: Open circuit and short circuit tests Rotor and stator resistance measurement These tests will be undertaken according to IEC Characteristic curves Characteristic curves include the following: Excitation System Tests Exciter Stability Open circuit curve Short circuit curve V-curve Zero power factor curve Unbalanced load-time curve Tests required are open circuit and short circuit tests. Exciter parameters Exciter parameters include transfer function, limiter settings, saturation factors, time constants, regulator gain etc. These parameters are checked during commissioning and again with excitation system replacement using either factory tests and/or computer simulation. IEEE is used as a standard. Tests carried out at commissioning and during excitation system replacement include: step response tests voltage ramping tests IEEE is used as a standard. The system operator criterion for testing the stability of the model is to model the synchronous compensator and exciter isolated from the system and to apply a step change to the exciter s voltage reference. The transient response of the synchronous compensator s terminal voltage should be stable and well damped. Figure 3 of IEEE Std shows the classical ideal control system response with 1.5 cycles to reach settling band and approximately 15% overshoot on the first oscillation. The response can be verified with a tested result. Other methods that can be performed (by test or simulation) to verify the stability of the excitation system are: Open loop frequency response Bode plots (used to obtain the gain and phase margins). Gain margin should typically be 6 db or more, and phase margin should typically be 40 or more. Closed loop frequency response Bode plots (used to obtain the peak amplitude response and the bandwidth).

43 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory GENERATING UNIT GOVERNOR/TURBINE AND FREQUENCY CONTROL Detailed Functional There are many different types of governor systems in use, and consequently, a large number of possible mathematical models to describe their dynamic behaviour. There are also many different types of fuel sources used for generation, which consequently have different governing requirements. For new equipment (which is largely digital based), the manufacturer will be able to provide a suitable model for dynamic studies together with the required parameters. These would be tested and verified (and if necessary, modified) at commissioning time. All modes of operation that the governor will use or have accessible whilst connected to the power system need to be fully tested. A description of these modes is to be attached to the submission of the ACS. Alternatively, a mathematical model can be selected based on its generic type, and an inspection of the schematics and other manufacturer documentation. Appropriate testing is then required to verify the model and parameters. All aspects of the plant which affect dynamic performance need to be modelled to a sufficient level to enable accurate simulation of the plant for up to 60 sec following a disturbance. For example, in hydro plant the effects of water column, surge tanks, tunnels, etc need to be included, where they significantly affect power output and response of the generating unit. Refer to: Hydraulic Turbine and Turbine Control Models For System Dynamic Studies IEEE paper 91 SM PWRS, IEEE Transactions on Power Systems, Vol. 7, No.1, February A detailed functional description of the governing system includes all subsystems (e.g. turbine, conduits, governor, supplementary controls etc.) and modes of operation (e.g. Islanded mode, grid etc.). Examples of standard models in use in the New Zealand system are: Steam Turbine Governor Models IEEEG1 IEEE Type 1 Speed-Governing Model With the appropriate choice of parameters, this is a recommended general model for steam turbine systems. IEEESGO IEEE General Purpose Turbine Governor With the appropriate choice of parameters, this general-purpose model gives a good representation of a steam reheat turbine. Gas Turbine Governor Models GAST Single shaft gas turbine. This model represents the principal characteristics of industrial gas turbines. More detailed variations of this model are also available starting with the same name. Hydro Turbine Governor Models Broadly, hydro governors fall into 3 categories Transient droop (Dashpot) governors Proportional-Integral-Derivative (PID) governors Tacho-accelerometric governors The first two are the most common and exist in various forms and configurations depending on the manufacturer. Several manufacturers also utilise certain features to enhance the performance of the governor system as well. There are also several types of turbine (prime mover) models: Linear flow-pmech characteristic Non-linear flow-pmech characteristic Linear flow-pmech characteristic (with relief valve) Non-linear flow-pmech characteristic (with relief valve) Kaplan turbine model Model with single penstock/tunnel supplying 2 machines Model with single penstock/tunnel supplying 4 machines

44 44 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory Relevant Standards Governor Parameters Standard governor/turbine models can be either split or combined and are mainly modified versions of the following: HYGOV Non-linear model for straightforward hydro governor and penstock with no surge chamber. HYGOVM Non-linear model suitable for detailed representation of surge chamber and penstock dynamics. IEEESGO Linear model for a simple hydro turbine configuration. IEEEG2/G3 Linear models for easily obtainable or exact data of a hydro turbine representation. IEC (1970), International Code For Testing Of Speed Governing Systems For Hydraulic Turbines. IEEE Std , Recommended Practice for Preparation of Equipment Specifications for Speed- Governing of Hydraulic Turbines Intended to Drive Electric Generators. IEC ( ), Guide for commissioning, operation and maintenance of hydraulic turbines. IEEE Std (R1992) IEEE Guide for Control of Hydroelectric Power Plants IEEE Std (R1994) IEEE Guide for Control of Small Hydroelectric Power Plants IEEE Std (R1997,2003) IEEE Recommended Practice for Functional and Performance Characteristics of Control Systems for Steam Turbine-Generator Units IEEE Std IEEE Guide for the Application of Turbine Governing Systems for Hydroelectric Generating Units Step Response Test The Step Response test is used to determine the governor system time-constant. It is also suitable for determining various governor parameters that can be extracted from results (for governors with proportional/proportional-integral control or transient droop). It is achieved by injecting a frequency step of 0.5 to 1.0 Hz (as seen in Figure 5) in the governor speed-sensing block while the unit is synchronised to the grid. For example, in the hydro turbine case, this test typically requires a single test carried out with the governor s speed feedback signal disconnected and replaced with a simulated signal. Any adopted methodologies will depend on the type of the turbine. For the PID governor other particular tests are required to determine all the governor parameters. The methodology employed in this case is based on standard control theory interpretations of the PID parameters. Test Connection Measurements The following test connections are required as a minimum for the Step Response test: Unit Simulated Speed Signal - % Unit Output Power - % Servo Ram Position (wicket gate position) or valve position -% It is also advisable to record system frequency in case external disturbances occur during the test Calculations The system time constant is determined from the response curve to the step change in speed signal. The system time constant is the time taken for the response curve to reach 63.21% of its final value starting immediately after the initial step (this is equivalent to the tangent to the curve at its inception, shown in blue in the figure below). Relevant Standards The inferred dashpot time constant is calculated from the system time constant as indicated in Figure 2 below. The final position (%), initial position (%) and time constant (s) can be directly measured from the graph. The ratio of permanent droop to temporary droop can then be calculated and used in the second formulae to calculate dashpot time constant. Where the initial step in gate position is difficult to determine the test can be repeated with the dashpot time constant increased to a large number. ANSI/IEEE Std , IEEE Recommended Practice for Preparation of Equipment Specifications for Speed-Governing of Hydraulic Turbines Intended to Drive Electric Generators. IEC (1991), Acceptance Tests for Steam Turbine Speed Control systems.

45 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory 45 Figure 2 System Loading Performance Methodology Frequency Response Test Method 1 (hydro turbines only) Stability of a governor is its inherent ability to regulate changes in load and provide positive damping to system disturbances. There are several ways this can be determined: Method 1: By testing the frequency response of the governor while connected to the system and loaded at 80% of P max. Method 2: By measuring the stable response of the governor during an actual system frequencydisturbance. The first method is commonly used on-site as a practical test to determine stability, and an example of this test can be found in the online portion of 5.6.3: Example governor frequency injection curves. Either method is accepted by the system operator as verification that the governor has a stable response. For example, in the case of hydro turbines, these are described in further detail below [and also in Appendix A3 (Frequency response) & Appendix A4 (Computer simulation) of IEEE Std ]. Stability is particularly important for the New Zealand power system, which comprises two island systems with a large proportion of hydro plant in both systems. Hydro plants are characterised by a water column that introduces an additional lag into the control loop, i.e. has a destabilising effect, whereas thermal plant is inherently more stable. New Zealand is also vulnerable to a greater magnitude of frequency transients due to the considerable proportion of a single unit as a percentage of total load or total generation at any given time. This test involves a series of tests carried out with the governor speed feedback-signal open looped and replaced with a simulated signal. The purpose of these tests is to determine the governor s frequency response characteristics. This test can also be simulated provided the model & parameters have been previously identified, and sufficient test results are available to match with simulations (to verify the model and parameters are accurate). IEC ( ) & IEEE Std both describe the general overview of this test, however the implementation described here differs in minor details. The requirements: System Frequency - should be within 0.1 Hz of 50 Hz during the tests. Wicket Gate Position - During the tests, the wicket gate velocity must not reach the maximum rate of

46 46 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory change and must not hit the end stops or any gate limit throughout the tests. The wicker gate position should be recorded along with the power, so a gate power curve can be created. The maximum servo rate should also be measured and recorded. This information will help in the formation of the governor model. High load so the full effect of the water column can be seen. Typically, Wicket Gate positions of 80% or greater are recommended. High Wicket Gate positions result in higher phase lags, due to the increased effect of the water column inertia, and lower system gains, due to the reduced effect of changes in Wicket Gate angle. The typical 80% gate position has been stipulated for these tests to ensure the servo ram does not reach the end stop. Unit Output Unit output power must follow closely to a sine wave. If the response is not a sine wave then only the fundamental is to be considered in the analysis Calculations According to the Nyquist criterion for stability of a control system, the open loop Nyquist plot must not encircle the critical point (-1, 0). The full open loop gain is determined by the following formula, MW Gain SpeedSig 1 D 2 H s H s = Inertia constant = La Place Operator (substituted by jω for a sinusoidal oscillation) D = Turbine Damping co-efficient MW = Change in power (pu) SpeedSig = Change in speed signal (pu) The magnitude and phase angle can be extracted and plotted on a Nyquist chart: MW Gain 2 SpeedSig [ D 1 (2 H 2 f ) 2 ] 0.5 Phase Phase MW SpeedSig 2. H.(2 f ) tan 1 D where, f Phase MW-SpeedSig = frequency of the injected speed signal = MW output peak to the speed signal trough phase shift Alternatively the open loop response can be plotted on a Bode plot using the following formula, Gain( db) = 20Log Gain The inertia constant is obtained as per generating unit parameter testing. Stability Criteria The definitions of gain and phase margins are shown in Figure 5 and Figure 6 respectively below. Traditional control theory suggests gain and phase margins of 3 db and 25 are the minimum requirement for stability. IEEE Std 125 defines suitable control with a gain margin of 8 db and a phase margin of 30. Either of these limits is acceptable.

47 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory 47 Figure 3: Nyquist Polar Chart Figure 4: Bode Chart Relevant Standards IEC ( ), International code for testing of speed governing systems for hydraulic turbines ANSI/IEEE Std , IEEE Recommended Practice for Preparation of Equipment Specifications for Speed- Governing of Hydraulic Turbines Intended to Drive Electric Generators.

48 Frequency (Hz) 48 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory Frequency response Method 1 (commonly injection frequencies) Some commonly injected frequency curves can be found in Figure 5 and Figure 6. These are example frequency injection curves only, which have been used in the past to categorise governor responses. Where available, offline testing can be very helpful to determine asset parameter values. Performance demonstrated offline is only representative of online-performance if the characteristics of offline governor mode are the same as the mode used once synchronised. Otherwise, testing must be carried out in the mode that the governor will be selected once synchronised Offline testing examples Figure 5 is an example of an offline parameter test. This can be used to calculate various governor parameters if the mode of testing is the same when operating online. A frequency step value of ±10% is typically used, although other step values can be used as long as the test accurately demonstrates the parameters being tested. Testing is not limited to this one injection trace. Under frequency open loop injection to test stability Time (s) Online testing examples Figure 5: Offline open loop frequency injection to demonstrate governor stability. Figure 6 demonstrates commonly injected online frequency traces. The purpose of trace 1 (the under frequency deviation in blue) is to characterise the governor response. The purpose of trace 2 (the over frequency deviation in red) is to prove that the over frequency response is the same as under frequency. Testing is not limited to these two traces. Extra testing is required to demonstrate the response to each discontinuous control block. These tests are specific to the type of governor / frequency control system being used. It is recommended that the model is constructed before the testing plan is finalised. This gives much greater visibility into what testing is required, the resolution of data required and what the response should look like. The under-frequency deviation (in blue) is defined by the following formula: Freq(t) = ( t)*exp(-0.95t) The over-frequency deviation (in red) is defined by the following formula: Freq(t) = ( t)*exp(-0.95t)

49 Frequency (Hz) Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory Online frequency injection example Time (s) underfrequency deviation overfrequency deviation Figure 6: Commonly injected frequency curves to demonstrate governor performance. Note: Instantaneous reserve testing is covered in Instantaneous Reserve. 5.7 FREQUENCY KEEPING EXAMPLE INJECTION CURVES Example frequency injection curve This section is just for frequency keepers and details a commonly used frequency injection curve that demonstrates the generators/ multiple generators (under station control) stability and minimum ramp rate. This test is applicable for generators which use governor control for frequency keeping. Generators which use other methods of frequency keeping should demonstrate stability and minimum ramp rate using tests adapted to the particular station. This test is conducted by injecting the frequency curve in Figure 7 (input frequency trace) into the frequency keeper control-system. The red trace is the required ramp rate (Minimum 10MW / minute). The time t1 and t2 are defined as follows: Test 1, demonstrating required ramp rate and ability to ramp to and from the frequency keeping bandwidth limits: t1 bandwidth /( ramp _ rate) t 2 2 bandwidth /( ramp _ rate) Test 2, demonstrating ramp response below the frequency keeping bandwidth limits: t1 bandwidth /(2 * ramp _ rate) t 2 bandwidth /( ramp _ rate) Where: ramp_rate = the contacted power change per minute of the generator. bandwidth = the maximum power deviation that is required from the frequency keepers dispatch offer. In example, for a frequency keeper with a bandwidth of ±50 MW, the bandwidth variable would be 50. Testing is not limited to only this curve; any extra functionality will require extra testing.

50 50 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory Figure 7: Reference frequency injection curve to demonstrate output response

51 Frequency (Hz) Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory INSTANTANEOUS RESERVE - GENERATOR FIR/SIR CAPABILITY General (Example tests that can be performed) This section details some basic technical requirements, and some example tests that can be used to demonstrate the Fast Instantaneous Reserve (FIR) and/or Sustained Instantaneous Reserve (SIR). The standard under-frequency curve is defined by the formula: Freq(t) = ( t) * exp( t) This same curve is used to demonstrate under-frequency ride through capabilities of the governor/frequency control system. The standard curve is used to measure the FIR and SIR output of the generator for both TWD (Tail water depression) and PLSR (Partially Loaded Spinning Reserve). The measurement periods for FIR (6 second) and SIR (60 seconds) are also shown in the figure Figure 8: Example frequency injection curves for FIR and SIR Calculating reserve capability The standard under-frequency curve is injected into the governor's speed input, while the generating unit is connected to the system. This will make the governor respond to the simulated under frequency event. For the purpose of calculating reserve from test results in this case, the following definitions apply: FIR is the additional MW output measured at 6 seconds after the start of the event (i.e. the MW output when the frequency reaches 48 Hz). SIR is the average additional MW output measured over the first 60 sec after the start of the standard under-frequency event, and sustained for at least 15 minutes after the start of the event. For PLSR the test should be carried out using different machine loads (e.g. 0, 20, 40, 60, 80% of full load) and synchronous condenser operation (if applicable), and cover the complete 60 sec period for the underfrequency event. Reserve capability may vary considerably with machine load. For completeness, TWD only needs to be tested with the initial condition of the generator motoring. For the duration of the test, (at least 60 seconds) the signals to measure are: system frequency governor frequency machine MW's gate or valve position Standard under frequency curve SIR measurement period Time (s) FIR measurement Period The system frequency is required as significant deviations from the nominal 50 Hz can affect results. Unless there is a real under-frequency event the system frequency should not vary by more than +/- 0.1 Hz, however this will partially depend on the amount of load the generating unit picks up during the test. Other items should be recorded at the start of the test: Load on other machines at the same station Turbine head/pressure levels The proportional setting (for calibration of model) The derivative setting (for calibration of model) If the head or steam pressure is likely to change significantly during the test, they should be recorded for the duration of the test in addition to the signals mentioned above. The plots of MW and frequency versus time (intervals and sampling to be at 100ms or less), together with the resulting FIR/SIR capability, at the various generating unit loads, are to be submitted to the system operator as tabular electronic data, to enable the tested response to be compared with the model response. Any plots should be provided in electronic form, to enable accurate calibration with the model.

52 52 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory 5.9 TRANSMISSION LINE General Tests This section details the basic technical requirements for the grid owner with respect to transmission lines The manufacturer or commissioning test reports should be able to supply suitable models together with the required parameters. Data supplied for modelling purposes by the manufacturer can be summarised in the following categories: Current-carrying conductor details (type, ground resistance, section length, etc.) Earth wire conductor details (type, number of, length) Cable data (cross-sectional area, current rating, etc.) positive and negative sequence data (reactance, resistance, susceptance, conductance) Zero sequence data (reactance, resistance, susceptance, conductance) Possible tests could be conducted for measuring the capacitance of the line by energising the line from one end and measuring CT secondary current and bus VT secondary voltage at the other end. All tests are to be performed to international standards. Relevant Standards IEEE Standards Engineering in Safety, Maintenance and Operation of Lines Collection (ESMOL) Edition (9 standards and guides) 5.10 HVDC HVDC Modulation Tests HVDC Equipment Tests Routine tests (as the grid operation permits) or as required by the system operator are: HVDC modulation tests Voltage stabilisation dynamic performance Staged faults Frequency stabiliser and spinning reserve sharing 250 MW North Island and 100 MW South Island generation trips Tests will be undertaken following CIGRE and/or the manufacturer s recommendations. Refer to: System tests for HVDC Installations." (WG 14.12), CIGRE Ref. No 97 Operational guidelines and monitoring of HVDC systems." (WG 14.23), CIGRE Ref. No. 130 Equipment integrity checks should be done by performing primary and/or secondary injections for verifying the following: Analogue and digital input/output signals. Control sequences and closed loop controls. Protection systems. IEEE Standard , IEEE Guide for Commissioning HVDC Converter Stations and Associated Transmission Systems Tests HVDC Tests expected to be undertaken at commissioning are: Steady state transmission tests AC and DC staged faults to verify overall system behaviour Runback tests

53 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory 53 Load rejection tests at 300 MW. Steady state with modulations on High power pole trips (to verify power transfer to other pole) AC system over voltage and frequency fluctuations Steady state and dynamic stability tests (current step response, power ramping) Tests will be undertaken following CIGRE and/or the manufacturer s recommendations. HVDC Equipment Equipment integrity checks should be done by performing primary and/or secondary injections for verifying the following: Analogue and digital input/output signals Control sequences and closed loop controls. Protection systems Relevant Standards IEEE Standard , IEEE Guide for Commissioning HVDC Converter Stations and Associated Transmission Systems AUFLS Tests Test Documentation Relay characteristics required by TRS should all be tested by secondary injection using a test set that is capable of ramping/stepping down voltages from above to below the set frequency with an accuracy of ± 0.01 Hz over the frequency range of 40 to 60 Hz. Measurements should be made with an appropriate time resolution that allows a clear assessment of capability Test results should be accompanied by: an explanation of the AUFLS scheme design; relay, instrumentation and control tripping logic; and an explanation of any under-frequency relay time delay detailing total operation time from when the frequency drops below the specified threshold until the load shedding isolating devices operate R & I Diagram The Relay and Instrument (R&I) diagram explains at a technically high level as to how the demand unit is expected to be tripped from the power system and should highlight any operational impacts. Examples of what can effect AUFLS operation could include the presence of automatic VT transfer schemes, automatic bus switching or automatic load transfer schemes. In the presence of such schemes application testing should be done to ensure reliable operation of the AUFLS scheme. The following is an example of a simple R&I diagram.

54 54 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory Logic Diagrams In order to evaluate the performance of the AUFLS system by analysis of test results some details of the protection and control logic must be included in the report. It is recommended that a standard logic diagram for all AUFLS blocks are developed and maintained, this will allow for an efficient assessment and understanding of the asset owner s equipment. These logic diagrams should include: explanation of any standard manufacture and custom logic blocks programed outputs control and tripping equipment and circuitry device types and implemented outputs and inputs The figure below shows an example of a standard DC and relay logic diagram.

55 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory 55

56 56 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory Settings The AUFLS settings, trip equation, and drive to lock details should be demonstrated. Any equations used to calculate the settings to prove compliance with the TRS obligations should be explained in the compliance report. For example in the SEL 351S relay the expected rate of change pickup time is calculated using the equation below. 81R1T Minimum Pickup Time = 81R1P Time Window Rate of frequency Change + 81R1PU A manufacturer provided time window table is needed because the design makes the pickup time of the element decrease as the rate of frequency change increases/decreases. The equation needs to be used to select the hold time delay so the element operates as desired, and should be explained in the report. The settings are best supplied in the report in the tabular form as shown in the example below. Trip Equations The trip and drive to lock out equations can be provided in the form of a logic diagram or equation. These equations or diagrams should express any supervisory elements specifically those in a logical AND with the frequency elements, as shown in the following examples. Trip Equation = N + 81D1T! IN R1T IN104 79DTL drive to lock out = 81D1T! IN R1T! IN104 In these equations the frequency elements are supervised by inputs IN104 and IN105 to the relay, this may be for manual or remote arming. These details should be explained and represented in the report. If voltage swing, sag, and swell interruption elements are enabled the study of its impact on AUFLS operation should be undertaken. It should be noted that compliance with operation times expressed in the TRS will be calculated using nominal frequency as the base.

57 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory 57 Varying Frequency tests Hold delay tests Voltage Frequency Block Tests Varying pickup frequency tests should confirm the reliability of the frequency elements, particular attention should be given to identify any mal-operation due to any inherent calculation errors and/or delays. The calculated frequency by the relay under test should be compared to that expected of the injected values and any discrepancies investigated. Tests should include: Relay pickup while varying the frequency injected by a test set. The signal should be varied from 52Hz down to 47.3Hz in 0.1Hz increments. Frequency rate of change pickup at a falling frequency injection. The rate of change of frequency (df/dt) is typically varied from 0.1 Hz/s to 2.2 Hz/sec in 0.1 Hz/sec increments. The results of these tests can be displayed in a similar manner as that explained in Graphical Representation These will confirm the specific pickup and hold times set out in the TRS. It is recommended that all potential AUFLS block settings within the relay capability be tested. The varying frequency tests are repeated with the relevant pick up and hold time tests enabled: Block1 primary set point, hold delay Block2 primary set point, hold delay Block2 secondary set point, hold delay Block3 primary set point, hold delay Block3 secondary set point, hold delay Block4 primary set point, hold delay Block4 secondary set point, hold delay Block4 rate of change set point, hold delay The results of these tests can be displayed in a similar manner as that explained in Graphical Representation The security of frequency elements relies on a healthy voltage signal in order to correctly calculate the system frequency. The impact of a degrading voltage on the frequency calculation should be fully tested. The TRS requires a voltage supervision of 50% nominal, if tests prove the requirement is not secure with the particular device the system operator should be notifed immediately. Recommended voltage block tests should be carried out by varying frequency at these voltage levels: 40% 50% 65% 85% 115% The results of these tests can be displayed in a similar manner as that explained in Graphical Representation Harmonic Distortion Tests The impact of harmonics on the system can cause a change in the length of a measured electrical cycle leading to error in some devices. The impact, if any, on the security of the frequency elements must be understood. It is recommended to repeat the varying frequency test allowing for hold delay times of relevant block(s) to be met, with, 5% 5 th harmonic 5% 11 th harmonic A combination of the most common harmonic voltages: V distortion = 1 V V V V % 11 th + 5% 13 th harmonics The results of these tests can be displayed in a similar manner as that explained in Graphical Representation

58 58 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory End to end tests The total AUFLS operating time should be tested with relay settings, control and tripping equipment in an as-left state. The AUFLS system should be tested with the varying frequency tests to ensure compliance with the TRS overall operation times. The trip coil should be monitored either in the relay or through the test set and results of these tests can be displayed in a similar manner as that explained in Graphical Representation Relay Event Records The technical details listed above subsections should provide the required background to allow a compliance assessment of the provided test reports and triggered device event records of the AUFLS system. The event records should be included in the report with the relays calculated/monitored frequency, injected current/voltages, DC logics, and monitored contacts (input/output) as relevant to the designed AUFLS system, as shown in the example below. End to end operation The total operating time requirements set out in the TRS must be itemised in the Test Report complete with supporting test results and additional documentation where required. The total operation time can be proven in a few different ways, for example, reports from an external monitoring devices such as fault recorders or on a test set report with operation times and details about how the test set was connected. This information must include the passing criteria programed in the test set and supporting analysis of device records as appropriate to ensure a clear understanding of the AUFLS systems compliance with the TRS. An example of a test set report screen is given below:

59 Doc File Name: GL-EA-010_Companion Guide for Testing of Assets.docx PDF Created on: 01/05/17 Appendix A Testing examples and theory 59 To help guide Asset Owners a template Compliance Report is located on the Transpower website document reference DT-EA-601 Extended Reserve Example TRS Compliance Report DISTRIBUTOR RESERVE CAPABILITY General This section details the basic technical requirements for all distribution asset owners offering Fast Instantaneous Reserve (FIR) and/or Sustained Instantaneous Reserve (SIR) in the form of interruptible load. For the purpose of calculating reserve from test results in this case, the following definitions apply: FIR is the drop in load that occurs within 1 second of the grid frequency falling to or below 49.2 Hz and sustained for a period of at least 60 seconds. SIR is the average drop in load (MW) that occurs within 60 seconds of the frequency falling to or below 49.2 Hz, and which is sustained until advised by the system operator. Basic Test Requirements Drop Load Test All tests need to be done by injecting a decaying frequency signal below 49.2 Hz into the underfrequency relay circuit to be able to time the chain of events after the under-frequency relay trips. An example of a frequency signal (the standard under-frequency curve ) used to simulate a typical underfrequency event can be seen below in Figure 9. The standard under-frequency curve in this example is defined by the formula: Freq(t) = ( t) * exp( t)