Instructions Manual LV Active Filter PQFT

Transcription

1 Instructions Manual Power IT LV Active Filter PQFT

2 Table of contents 1. SAFETY INSTRUCTIONS UPON RECEPTION DELIVERY INSPECTION IDENTIFICATION TAG STORAGE LONG STORAGE PERIOD AND REFORMING PQFT PRINCIPLE AND CHARACTERISTICS REASONS FOR LIMITING HARMONICS GENERAL PRINCIPLE OF ACTIVE FILTERING THE ABB ACTIVE FILTER: THE PQFT THE PQFT: PERFORMANCES Filtering Reactive power EMC COMPONENTS DESCRIPTION AND IDENTIFICATION COMPONENTS DESCRIPTION PQF current generator The control COMPONENTS IDENTIFICATION MECHANICAL INSTALLATION GENERALITIES IP00 PLATE Mounting of the plate Master cubicle door accessories Slave cubicle door ELECTRICAL INSTALLATION OVERVOLTAGE POWER CABLES AND EXTERNAL PROTECTION CURRENT TRANSFORMERS/CONTROL CABLES SELECTION CURRENT TRANSFORMERS INSTALLATION CT s connection to the PQFT CT s connection topology: cases Case 1: Global compensation one feeding transformer Case 2: Individual compensation one feeding transformer Case 3: global compensation transformer busbar not accessible Case 4: two independent feeding transformers Case 5: back up generator CONNECTION OF LAMPS AND BUTTONS (IP00 VERSION) PRECAUTIONS WITH CAPACITORS MASTER-SLAVE INTERCONNECTIONS INTRODUCTION MECHANICAL INSTALLATION (CUBICLE VERSION) ELECTRICAL CONNECTIONS Connections between sections Power connection Control connection Domino boards connection Earth connection Connections to the supply Power connection Protective earth

3 8. PQF-PROG INSTALLATION AND PC CONNECTION SYSTEM REQUIREMENTS INSTALLING PQF-PROG ON YOUR PC HARDWARE CONNECTION COMMISSIONING STEP STEP STEP PQF connection diagram Material needed & hypotheses for correct measurements Checking the correct connection of the CTs with a two channel scopemeter Measurement of CT in phase L Measurement of CT in phase L2 and L Checking the correct connection of the CTs with two current probes Checking the correct connection of the CTs with a Fluke 41B STEP With PQF-Prog With the PQF-Manager STEP STEP STEP STEP OPERATION NORMAL WORKING SEQUENCE ADDITIONAL INSTALLATION INSTRUCTIONS FOR THE PQFT IN THE PRESENCE OF PLAIN CAPACITORS BEHAVIOR IN CASE OF POWER OUTAGE BUTTONS, LIGHTS AND LED S SIGNIFICATION Master cubicle Slave cubicle PQF-Manager Control rack PROGRAMMING WITH PQF-PROG Filter operation principle Starting Programming the filter PROGRAMMING WITH PQF-MANAGER Filter operation principle Keys identification Programming the filter PQFT AND NETWORK MONITORING WITH THE PQF-MANAGER Filter status Network status Waveform Spectrum REMOTE CONTROL AND ALARM CONTACT Remote control Alarm contact PROTECTIONS FAULT HANDLING AND TROUBLESHOOTING FAULT HANDLING Type of faults Fault handling and fault clearance procedure TROUBLESHOOTING Frequent problems occurring at commissioning stage Error codes meaning Faults not related to error codes Restarting the filter after fault correction

4 12. MAINTENANCE MAINTENANCE FREQUENCY MAINTENANCE PROCEDURE FAN CAPACITORS REFORMING

5 1. Safety instructions These safety instructions are intended for all work on the PQFT. Neglecting these instructions can cause physical injury and death. All electrical installation and maintenance work on the PQFT should be carried out by qualified electricians. Do not attempt to work on a powered PQFT. After switching off the mains, always wait at least 15 minutes before working on the unit in order to allow the discharge of DC capacitors through the discharge resistors. DC capacitors might be charged to more than 800V. Before manipulating current transformers, make sure that the secondary is short-circuited. Never open the secondary of a loaded current transformer. You must always wear isolating gloves and eye-protection when working on electrical installation. Also make sure that all local safety regulations are fulfilled. WARNING: WARNING: WARNING: This filter contains capacitors that are connected between phase and earth ; a leakage current will flow during normal operation, therefore a good earth connection is essential and must be connected before applying power to the filter. If the ground is defeated, certain fault conditions in the unit or in the system to which it is connected can result in full line voltage between chassis and earth ground. Severe injury or death can then result if the chassis and earth ground are touched simultaneously. The neutral current in PQFT filter may be as high as 3 times the line current hence please do not use a 4 pole breaker to connect this type of filter as the rating of the neutral pole may not be adequate. 5

6 2. Upon reception 2.1. Delivery inspection Each PQFT is delivered in a sealed package designed to protect adequately the equipment during shipment. Upon receipt of the equipment, make sure that the packing is in good condition. After removal of the packing, check visually the exterior and interior of your filter. Any loss or damage should be notified immediately. Care should be taken to ensure that correct handling facilities are used Identification tag Each PQFT is fitted with a nameplate for identification purposes. The nameplate includes the type of filter, nominal frequency, voltage and current as well as a serial number and an ABB internal article code. This information should always remain readable to ensure proper identification during the whole life of the filter Storage PQFT packing is made for an indoor storage period of maximum six months (transport time included from delivery date EXW ABB Jumet factory). Packing for longer storage period can be done on request. If your PQFT is not installed once unpacked, it should be stored in a clean indoor, dry dust free and noncorrosive environment. The storage temperature must be between 15 C and 70 C with a maximum relative humidity of 95%, non-condensing. Before installing and operating your PQFT, you should read very carefully this instructions manual and you should make sure that the information given on the nameplate corresponds to your network Long storage period and reforming If your PQFT is non-operational or stored for more than one year, the DC capacitors need to be reformed (reaged). Without reforming, capacitors may be damaged when the filter starts to operate. The reforming methods are described in chapter 12 (maintenance). 6

7 3. PQFT principle and characteristics 3.1. Reasons for limiting harmonics Power electronics based equipment is the main source of the harmonic pollution in electric networks. Examples of such equipment include drives (AC or DC), UPS s, welders, PCs, printers etc. In general, the semiconductor switches in this equipment conduct only during a fraction of the fundamental period. This is how such equipment can obtain their main properties regarding energy saving, dynamic performance and flexibility of control. However, as a result a discontinuous current containing a considerable amount of distortion is drawn from the supply. Harmonic pollution causes a number of problems. A first effect is the increase of the RMS-value and the peak-value of the distorted waveform. This is illustrated in figure 3.1. that shows the increase of these values as more harmonic components are added to an initially undistorted waveform. The RMS-value and the peak-value of the undistorted waveform are defined as 100 %. The peaks of the fundamental component and the distortion components are assumed to be aligned. It may be seen that the distorted waveform, which contains harmonics up to the 25th harmonic, has a peak value that is twice the value of the undistorted waveform and a RMS-value that is 10 % higher. 100 % H % H % H5 + 4 % H25 Peak: 100 % 133 % 168 % 204 % RMS: 100 % 105 % 108 % 110 % Figure 3.1. Evolution of the increase in peak-value and the RMS-value of a waveform as more harmonic components are added The increase in RMS-value leads to increased heating of the electrical equipment. Furthermore, circuit breakers may trip due to higher thermal or instantaneous levels. Also, fuses may blow and capacitors may be damaged. kwh meters may give faulty readings. The winding and iron losses of motors increase and they may experience perturbing torques on the shaft. Sensitive electronic equipment may be damaged. Equipment, which uses the supply voltage as a reference may not be able to synchronise properly and either applies wrong firing, pulses to switching elements or switch off. Interference with electronic communications equipment may occur. Distorted networks may also cause generators malfunctions. Homopolar harmonics (third and multiple of three) generated by loads connected between phases and/or loads connected between phase and neutral are strictly in phase. When the neutral is connected, the homopolar currents are added in the neutral line. 7

8 Fundamental 3th L1 Fundamental 3th L2 Fundamental 3th L3 3th N 8

9 PQFT Instructions Manual This situation becomes critical when the neutral conductor section is only a fraction of the line conductor. This excessive neutral conductor temperature is witnessed sometimes leading to neutral conductor destruction. Overall it may be concluded that an excessive amount of harmonics leads to a premature ageing of the electrical installation. This is an important motivation for taking action against harmonics General principle of active filtering The active filter measures the harmonic currents and generates actively a harmonic current spectrum in opposite phase to the measured distorting harmonic current. The original harmonics are thereby cancelled. The principle is shown in figure 3.2. Supply Fundamental only i distortion Load i compensation PQFT Figure 3.2. Principle of active filtering The control of the active filter in combination with the active generation of the compensating current allows for a concept that may not be overloaded. Harmonic currents exceeding the capacity of the active filter will remain on the network, but the filter will operate and eliminate all harmonic currents up to its capacity. The principle of active filter showing currents and spectra is clarified in Figure

10 PQFT Instructions Manual Waveforms Harmonics Clean feeder current = Load current + Active Filter current Figure 3.3. Active filter principle illustrated in time and frequency domains 3.3. The ABB Active filter: the PQFT. As we have just seen, the active filter is basically a compensating current generator. The most important parts are then the current generator and the control system. The compensating current is in a first step created by a three-phase Insulated Gate Bipolar Transistors (IGBT) inverter bridge that is able to generate any given voltage waveform with PWM (Pulse Width Modulation) technology. The IGBT bridge uses a DC voltage source realised in the form of a DC capacitor. The inverter bridge is in fact the same technology than in AC drives. The generated voltage is coupled to the network via reactors and a small filter circuit. The desired current generator is thereby achieved. The DC capacitors are loaded actively through the inverter bridge and there is no need of external power source. Obviously, the DC voltage level must always be higher than the peak value of the network voltage in order to be able to inject currents to the network. To control the active filter the choice stands between open loop and closed loop current control. Under open loop current control, the harmonics currents are measured on the load side of the active filter that computes the required compensating current and injects it into the network. Closed loop current control as performed by the PQFT is shown in Figure 3.4. In this topology the resulting current to the network is measured and the active filter operates by injecting a compensating current minimising this resulting current. In this configuration, the filter directly controls its effect on the filtration. 10

11 AF Target Control Output Measurement Feedback Figure 3.4. Closed loop control In addition to being more precise, the closed loop control system also allows for a direct control of the degree of filtering. Furthermore, the closed loop control system ensures that measurement errors do not result in a higher distortion. To fully exploit the potential of an active filter we need a digital measurement and control system that is fast enough to operate in true real time. We need to be able to track the individual harmonics and control the compensating current according to the requirements of the plant and this with full control at every instant in time. To achieve this, we need advanced Digital Signal Processors, DSP s. Among the physical signals needed by the PQFT, the three line currents have obviously to be measured. Standard CTs with 5A secondary are usually sufficient. Those analogue signals must first be acquired, levelled and antialias-filtered before digitalisation. Fast and high precision analogue-to-digital converters are used to create a digital representation of the analogue signals. The digitised signals are then sent to the powerful DSP that controls all measurements and calculations in real time, and builds the PWM references for the inverter. It is another processor, a microcontroller, which handles all digital input/output (including the command of the PWM inverter). More dedicated to control than to calculations, this microcontroller ensures for instance the closing of the relays and contactors. One control is needed per PQFT system and can handle more than one power module simultaneously. 11

12 3.4. The PQFT: performances Filtering The main requirement for an active filter installed in an industrial installation is to attenuate the harmonics produced by the non-linear loads of the installation. The ideal active filter should allow the user to choose freely which harmonic components to filter and should offer an adjustable degree of filtering. It is also worth noting that the total harmonic voltage distortion at the point of common coupling (PCC) is often calculated up to the 40 th [1] or the 50 th [2] harmonic. Furthermore, the total number of harmonics that can be filtered determines directly the quality of the resulting current. This is illustrated in figure 3.5., which shows the filtered waveforms obtained by filtering up to different harmonic levels. (a) Filtering up to the 13 th harmonic. (b) Filtering up to the 25 th harmonic. (c) Filtering up to the 50 th harmonic. Figure 3.5. Waveforms obtained by eliminating the harmonic components of a rectangular periodic signal up to the (a) 13 th harmonic, (b) the 25 th harmonic and (c) the 50 th harmonic This figure highlights the need for an active filter that can operate up to sufficiently high harmonic frequencies. The PQFT can filter simultaneously 15 (12) independent harmonics up to the 50 th for 50Hz (60Hz) based networks. The number of harmonics to be filtered as well as their frequencies is completely programmable by the user. Besides the harmonic selection functionality, the user has also the possibility to specify a filtration level for each selected harmonic. The PQFT will filter the selected harmonics until the filtration level set by the user is reached. This filtration level can be different for each selected harmonic. This functionality is especially useful when the objective is to fulfil the requirements of a standard and results in a better use of the available compensation power. It also allows the installation of active filters on networks already fitted with a fixed passive filter. We can see that we are very close to the ideal filter: the choice of which harmonic components to filter is free and the degree of filtering is adjustable according to the wishes of the user. Moreover, all typical harmonics generated by non-linear loads may be filtered simultaneously. 12

13 Reactive power Besides the filtering functionality, reactive power compensation is also possible with the active filter. Compared to traditional capacitor banks, the reactive compensation of the PQFT is continuous ( stepless ), fast and smooth (no transients at switching). The compensation can be either capacitive or inductive. Two types of compensation are available: automatic compensation where a target power factor has to be set, and fixed compensation based on a predefined amount of kvar EMC The PQFT has been verified for compliance with EU (European Union) directives for EMC (electromagnetic compatibility) for operation at 50 Hz and bears the CE-mark to this effect. However it is assumed that the installation is done as per the instructions in this manual. When an apparatus is used in a system, EU directives may require that the system is verified for EMC compliance. For EMC reasons, the cubicle should be connected to the main protective earth connection with yellow-green wire. This wire should be as short as possible. 13

14 4. Components description and identification 4.1. Components description As already explained, the active filter is basically composed of two parts: the current generator and the control system. Non-linear load(s) - three-phase with or without neutral connection - single-phase Current measurement Compensation current PQF Digital Control PQF current generator PQF current generator. The power circuit of the ABB active filter PQF is represented hereafter. Power Lines Preload Main Breaker PWM Reactors + Output Filter PWM inverter - The main components are: - PWM inverter - PWM reactors - Output filter - Preloading circuit The current generator is physically organised in power modules, each including a PWM inverter, a threephase PWM reactor and the output filter. Each PQFT plate or cubicle contains one power module. Protection is realized through fuses and there is one preloading circuit. The PWM inverter is composed of DC capacitors and an IGBT inverter bridge. This system is able to generate any voltage waveform with PWM technology. 14

15 The physical layout of a PWM inverter module is shown hereafter. Each PWM inverter is fitted with a local electronic control called the domino board. The domino board is controlled by the central DSP. The domino board is fitted with jumpers noted JP100, JP101, JP102, JP103, JP104, JP105, JP106, JP109 and JP110 (JP107 and JP108 are off). In case of several power modules, only the domino board of the last slave is fitted with jumpers. Please refer the photo below. The PWM reactors convert the voltage created by the PWM inverter into currents that will be injected in the network. The output filter consists in line reactors and an RC shunt circuit. The function of the preloading circuit is to avoid at start-up high inrush currents that could damage the power electronics or create transients in the network. 15

16 The control For best performances, the control of the PQFT is Digital Signal Processor (DSP) based. The three lines currents are measured by external CT. Those analogue signals must first be acquired, levelled and antialias-filtered before digitalisation. Fast and high precision anlogue-to-digital converters are used to create a digital representation of the analogue signals. The digitised signals are then sent to the powerful DSP that controls all measurements and calculation in real time, and builds the PWM references for the inverter. It is another processor, a microcontroller, which handles all digital input/output (including the command of the PWM inverter). More dedicated to control than to calculations, this microcontroller ensures for instance the closing of relays and contactors. One control unit may command up to 4 power modules Components identification Control PQF Manager Main fuses PWM inverter Auxiliary voltage transformer Output filter capacitor Fan 16

17 A more detailed identification is given in the following pages. The identification hereafter is related to the drawings of the following pages. Internal views indicate the position of identified components but fixation details are not included. Although visible on the drawings, some components may actually be hidden in the real structure. Mains connection F102 K10 mains fuses mains contactor Fan M101 fan motor Auxiliaries Q101 T101 breaker for auxiliaries auxiliary voltage transformer PWM inverter U11 A67 A77 A104 A105 A117 IGBT module AC voltage board Domino interface DC voltage converter DC voltage converter Domino board Output filter C11 L11 L12 L13 Output filter capacitor Line reactor Line reactor Line reactor PWM reactor L21 L22 L23 PWM reactor PWM reactor PWM reactor Preloading circuit K11 Preload contactor R14/15 Preload resistors U1 Preload bridge 17

18 Control rack A111 A112 A113 A119 A114 A115 A116 U109 X1 X4 X2 X10 X6 Digital I/O board Interface board IGBT s and DSP Digital Signal Processor (DSP Board) Interface PQF Manager board Current input board Analog input board +24V power supply board Power supply + 5V Terminal block digital I/O wiring Terminal block current input wiring Terminal block analog input wiring Terminal power supply wiring Terminal current input wiring Door components S102 S101 S104 H101 H102 H103 A120 RESET push button RUN push button Remote local switch White lamp: controller connected to supply (auxiliary breaker closed) Red lamp: MCB closed Green lamp: MCB open PQF-Manager Other components A121 X5 X12 X21 +24V switching power supply Terminal block backplane wiring (external CT connection) Terminal signalling wiring Terminal intercabinets wiring 18

19 Master + slave IP00 19

20 20

21 Control rack details 21

22 5. Mechanical installation 5.1. Generalities The PQFT is suitable for indoor installation, on firm foundations, in a well-ventilated area without dust and excessive aggressive gases where the ambient parameters do not exceed the following values: 40 C max (including the PQFT heat generation); (please refer to page 23) 30 C (average temperature) over 24 hours; Minimum temperature: +5 c Humidity less than 95% RH non-condensing Altitude: max. 1000m without derating. For units with nominal voltage above 415V, the rear side of the cubicles must be located at least at 100mm from the wall. PQFT cubicles (IP23 version) have standard dimensions of 600 x 600 x 2150 mm (width x depth x height). PQFT plates (IP00 version) have standard dimensions of 499 x 400 x 1696 mm (width x depth x height). Each cubicle or plate is fitted with one power module, its own bottom cable entry (top cable entry on request), fuses and contactor. Standard arrangement for PQFT with up to 3 power modules are shown on page 23. A maximum of 4 power modules may be connected in parallel.!!!!!!!!!!!!!!!! Only modules of the same ratings may be paralleled!!!!!!!!!!!!!!!!!!!!!!! CAUTION The PQFT dissipates significant amounts of heat; 3 kw/module that has to be evacuated out of the room where the filter is located. Otherwise, you may experience excessive temperature rise. Please note life of electrical equipment decreases drastically if the operating temperature exceeds the allowable limit. 22

23 For proper cooling of the PQFT, a minimum airflow of 610 m 3 /h of cooling air has to be supplied to the each fan of the unit. Please ensure the air used for cooling does not contain conductive particles, significant amounts of dust, or corrosive or otherwise harmful gases. The cooling air intake temperature cannot exceed 40 C under any operating condition. The fan inlet must not be covered by any object and located at a sufficient distance from walls to ensure a correct air flow. The hot exhaust air has also to be properly ducted away. 23

24 5.2. IP00 plate Mounting of the plate The IP00 mounting plate is to be fixed in your own cubicle by means of the four holes located in the corners of the plate. Please refer to the attached diagram. Six holes are provided to fix the plate in the cubicle with M8 screws. The holes at halfway up are used to clamp the plate in the cubicle and to increase its rigidity while the other ones are mainly for the principal fixations. For proper cooling of the PQFT, a minimum airflow of 610 m 3 /h of cooling air has to be supplied to each fan of the unit. It must be fed with fresh air through the bottom of the door and it must be free to go out from the top of the cubicle. Please ensure the air used for cooling does not contain conductive particles, significant amounts of dust, or corrosive or otherwise harmful gases. 24

25 Master cubicle door accessories The dimensions of the cut-out to be made on the master cubicle door are represented here below. There are 6 holes for buttons and lamps (same dimensions) and the cut-out for the PQF-Manager (if delivered). The buttons and lamps are provided with the filter. The positions of the cutout are those of the IP23 version and are given for indication only. Also please follow the following steps to fit the metallic cover on PQF-Manager as follows: - unscrew the RS232 spacer screws on the PQF-Manager itself - place the manager on one side of the door and the metallic cover on the other side - hold the cover with the spacer screws - fix mechanically the whole assembly to the door Slave cubicle door Only one lamp is provided to be installed on slave cubicle doors. The dimension of the cutout is the same than for the master cubicle door (diameter: 23 mm). 25

26 6. Electrical installation Your PQFT is a parallel active filter: it is installed in parallel with the load(s). Connection implies: - 3 power cables - 1 neutral cable - 3 CT (one per phase) - 6 control wires for the CT - Ground/PE 6.1. Overvoltage The PQFT is able to withstand continuously a voltage (inclusive of harmonics but not transients) of up to 110 % of the rated voltage. Higher voltages than the rated one would imply an operation at limited power of the filter. Since operation at the upper limits of voltage and temperature may reduce its life expectancy, the PQFT should not be connected to systems for which it is known that the overvoltage will be sustained indefinitely Power cables and external protection Each cubicle is fitted with its own fuses (bottom cable entry (top cable entry on request)) and needs to be individually connected to the supply. The power cable size should be rated on the basis of X times the nominal current of the corresponding cubicle (one or two power modules) where X is a multiplication factor which allows to take into account the skin effect. This multiplication factor is the result of an iterative calculation and can be determined by means of the following process: Important remark: please note that the following process is made to take into account the skin effect only. Other deratings due to local standards and/or installation conditions (as e.g. cables proximity, number of cables connected in parallel, ) have to be taken into account by the company responsible for the PQF cable connection. Step 1: as initial value of this iterative process, determine the preliminary cable section on the basis of the nominal current. Step 2: based on the previously determined cable section, find in the table here below the multiplication factor that must be applied. Step 3: determine the cable section on the basis of the value of the multiplication factor times the nominal current. - if the cable section found is equal to the previously found cable section, the process can be stopped. The cable section is then determined taking into account the skin effect. (see examples below) - If the cable section found is bigger than the previously found value, step 2 and 3 have to be repeated until the cable sections are equal (see example below). 26

27 Section 50Hz 60Hz [mm 2 ] Al Cu Al Cu Table: Multiplication factors for different cable types Example: Please note that the following example is given for information only (see important remark above). PQF-T 70A 400V 50hz Phase cables sizing Step 1: I N = 70A cable section (*) = 25 [mm 2 ] Step 2: multiplication factor for a 25 [mm 2 ] copper cable at 50hz = 1.02 Step 3: I = I N x 1.02 = 70A x 1.02 = 71.4 A Step 4: I = 71.4 A cable section (*) : 25 [mm 2 ] This section is equal to the section found in the previous step. Result : one copper cable of 25 [mm 2 ] per phase (*) given for information only. Neutral cable sizing Step 1: I N = 210A cable section (*) = 120 [mm 2 ] Step 2: multiplication factor for a 120 [mm 2 ] copper cable at 50hz = 1.1 Step 3: I = I N x 1.1 = 210A x 1.1 = 231 A Step 4: I = 231 A cable section (*) : 120 [mm 2 ] This section is equal to the section found in the previous step. Result : one copper cable of 120 [mm 2 ] for neutral cable connection. (*) given for information only. If single core cables are used an alloy gland plate is recommended. The neutral current in PQFT filter may be as high as 3 times the line current hence please do not use a 4 pole breaker to connect this type of filter as the rating of the neutral pole may not be adequate. PQF-T copper bar dimensions for connection of phases and neutral cables: 30 mm x 10 mm (hole: = 11 mm) 27

28 NOTE: Due to the LCL output filter of the PQF, there is no radiated emission through the feeding cables. Consequently, there is no need for special screening of the incoming cables. In case of regenerative loads (e.g. loads that may inject active energy to the network, usually called 4Qloads), it is very important to connect the PQF outside the protection of this load. Indeed, consider Figure 6.1 where a common protection is installed for both the regenerative load and for the PQF. When the load reinjects energy to the network and the mains protection trips, the whole energy may be pushed into the PQF, which may cause severe inquires to it. Figure 6.2 shows the admitted protection scheme for regenerative loads. In this case, if the breaker of the load trips, the PQF is isolated from the fed back energy. PQF 4Q load PQF 4Q load Figure 6.1. Incorrect connection Figure 6.2. Correct connection 6.3. Current transformers/control cables selection Three CT s are needed since the PQFT monitors the three phases and neutral of the network. The proper operation of the PQFT does not require any special CT s. The requirements are minimum: 5A of secondary 15 VA minimum for up to 30 meters of 2.5 mm² cable Class 1 accuracy or better Ratio limit above maximum line current In case the CT s are shared with other loads, the VA burden shall be adapted and the connection of the different loads (including the PQFT) must be in series. Twin 2.5 mm² control cable is the most suitable for this application. In order to determine the suitable CT s for your application, please refer to the following chart. 28

29 Maximum rms current of the downstream loads (including starting current of DC drives): X1 =.. Arms Multiply X1 by 1.6: X2 =. Arms YES NO CT cables > 30 meters? Select 3 identical CT s such that: - rating at primary X2 - rating at secondary: 5A - Burden 15 VA - Class 1 accuracy or better Section of CT cables: 2.5 mm²? (recommended) YES Determine the length of CT cables (meters) L = m X3 = (L x x 25) + 10 X3 = VA Select 3 identical CT s such that: - rating at primary X2 - rating at secondary: 5A - Burden X3 VA - Class 1 accuracy or better NO Determine the length (m) and resistance (Ω/m)of CT cables (meters) L = m R = Ω/m X4 = (L x R x 25) + 10 X4 = VA Select 3 identical CT s such that: - rating at primary X2 - rating at secondary: 5A - Burden X4 VA - Class 1 accuracy or better 29

30 6.4. Current transformers installation Special care has to be taken for the connection and location of the CT s: it is the most current source of problems occurring at commissioning stage. WARNING: when connecting the CT s to the PQFT, the secondaries of the CT s have to be shortcircuited. First of all, the CT s have to be positioned for closed loop control: they have to monitor the resulting current after filtering. The CT s must also be positioned in the correct direction around the power cable: the K (or P1) side should be in the direction of the supply and the L (or P2) side should be in the direction of the load CT s connection to the PQFT The connections between the CT s and the filter must satisfy the following scheme: The k terminal of line 1 CT is connected to terminal X5-1 of the filter The l terminal of line 1 CT is connected to terminal X5-2 of the filter The k terminal of line 2 CT is connected to terminal X5-3 of the filter The l terminal of line 2 CT is connected to terminal X5-4 of the filter The k terminal of line 3 CT is connected to terminal X5-5 of the filter The l terminal of line 3 CT is connected to terminal X5-6 of the filter Supply side L1 L2 L3 N K k l L K k l L K k l L Load side L1 L2 L3 N X5.6 X5.5 X5.4 X5.3 X5.2 X5.1 PQF 30

31 CT s connection topology: cases The location of the CT s is critical to ensure the proper operation of the active filter. The CT s are the eyes of the filter and it will react in accordance with the information supplied by them. The location of the CT s must always be in closed loop configuration. This means that the CT s must see the load current and the filter current. In some cases, summation CT s might be needed to fulfil the closed loop requirement. Typical circuit topologies and adequate CT s location are described hereafter in the following order: Case 1: Global compensation one feeding transformer. Case 2: Individual compensation one feeding transformer. Case 3: Global compensation transformer busbar not accessible. Case 4: Two independent feeding transformers. Case 5: Back up generator. Please bear in mind that the active filter always needs 3 CT s: one per phase. There is also one shorting bridge per CT input on terminal X5. Those bridges must be removed only when the secondary circuit of the CT is closed. 31

32 Case 1: Global compensation one feeding transformer This is the most frequent configuration: one transformer feeds several non-linear loads. The active filter is installed in central position and filters the combined harmonic currents. This configuration and the proper location of the CT s is represented hereafter. PQF LOAD LOAD LOAD Figure 6.3. Global compensation one feeding transformer. The connection of the CT s to the active filter must be as represented herafter: Supply side L1 L2 L3 N K k l L K k l L K k l L Load side L1 L2 L3 N X5.6 X5.5 X5.4 X5.3 X5.2 X5.1 PQF K = P1, L = P2, k = S1, l = S2 Figure 6.4. CT s connection to the active filter. 32

33 Case 2: Individual compensation one feeding transformer Instead of installing one active filter in central position, it also possible to connect the active filter and its CT s so that it compensates one particular load only. In the example hereafter, the active filter PQF is connected to compensate Load 1 only. It does not see load 2. LOAD 2 PQF LOAD 1 Figure 6.5. Individual compensation one feeding transformer The connection of the 3 CT s to the active filter is described in Case 3: global compensation transformer busbar not acce ssible. The active filter is required to filter the loads of side A and side B but the transformer busbar not being accessible, the CT s cannot be installed in central position. LOADS (Side A) LOADS (Side B) PQF Figure 6.6. Transformer busbar with no access: single-line diagram For this configuration, three CT s (one per phase) have to be installed on side A et on side B (in total, 6 CT s). Those CT s will then feed 3 summation CT s (one per phase) that are connected to the active filter. This CT topology is represented in figure

34 CT 1 (one per phase) Primary: X Secondary: 5A CT 2 (one per phase) Primary: X Secondary: 5A Summation CT (one per phase) Primary 1: 5 A Primary 2: 5A Secondary: 5A LOADS (Side A) LOADS (Side B) PQF Figure 6.7. Transformer busbar with no access: CT connection (to be done for each phase) The CT s installed in each phase of side A et B (CT1 and CT2) must be identical (X / 5) and feed a summation CT whose secondary is 5A (5+5/5A). The summation CT is then connected to the active filter in accordance with chapter A total of 3 summation CT s (one per phase) must be used. The CT ratio to be programmed in the filter is: 2X / 5. The CT summator PQF connection is represented here below. This has to be done for each phase. P1, K S1, k P1 P2, L S2, l P1, K S1, k P2 P1 S1 S2 k l P2, L S2, l P2 PQF Side A Side B Figure 6.8. Connection between CT1, CT2, the summation CT and PQF for one phase. 34

35 Case 4: two independent feeding transformers. Two independent transformers (the tie is normally open) feeds two different set of loads. One active filter is fitted on each LV busbar. This system may however also work in degraded mode: the tie is closed and only one transformer feeds the whole LV system. By connecting the CT s as described hereafter, it is still possible to filter properly the harmonics and to correct the power factor. T1 T2 PQF PQF Figure 6.9. Two independent transformers: single-line diagram T1 T2 S1, k P1, K P1, K S1, k S2, l I1 P2, L P1 K I0 P2 L I2 P2, L S2, l S1 k S2 l P1 P2 P1 P2 P1 P2 P1 P2 S1 S2 S1 S2 I 1-I 0 k l k l PQF 1 PQF 2 I 2+I 0 Figure Two independent transformers: CT connection for one phase. 35

36 For each phase, 3 CT s must be installed: - one to measure I1 - one to measure I2 - one to measure I0. Those CT s must be identical: X/5 A. CT I1 and CT I0 feed a summation CT which is connected to PQF1. CT I2 and CT I0 feed a summation CT which is connected to PQF2. Those summation CT s must be 5+5 / 5 A. Condition 1: the tie is open. PQF1 sees I1 and PQF2 sees I2 (I0 = 0). The two transformers work independently and the total current to be compensated is I1 + I2. Condition 2: the tie is closed but both transformers feed the loads. In this configuration, PQF1 sees (I1-I0) and PQF2 sees (I2+I0). The total current seen by the two filters is I1 + I2. Condition 3: the tie is closed but only one transformer feeds the loads (degraded mode). If only T1 feeds the loads with the tie closed, PQF1 sees (I1-I0) and PQF2 sees I0 (I2 is zero). If only T2 feeds the load, I1 will be zero. The above described connection must be done for each phase. The CT ratio to be programmed in the filter is: 2X/ Case 5: back up generator Many installations are fitted with back up generators to ensure the proper operation of the installation in case of mains power outage. A typical configuration is given here below. G LOAD PQF Figure Back-up generator: typical single-line diagram 36

37 The CT connection must be such that the active filter works whatever the type of supply: generators or transformer-mv network. For each phase, one CT is installed in the transformer feeding and one in the generator. Those two CT s must be identical (X / 5 A) and are connected to a summation CT rated 5+5 / 5 A. The CT ratio to be programmed in the filter is: 2X/5. G P1, K S1, k P1 P2, L S2, l P1, K S1, k P2 P1 S1 S2 k L P2, L S2, l P2 PQF Figure Back-up generator: CT connection (for one phase) 6.5. Connection of lamps and buttons (IP00 version) The buttons and lamps have to be connected to terminal X20 according to the following table for the master cubicle: Item Connection points Green lamp (H103) X20-4 / X20-3 Red lamp (H102) X20-5 / X20-3 White lamp (H101) X20-6 / X20-3 Local-remote switch (S104) X20-7 / X20-8 (local) / X20-9 (remote) Run button (S101) X20-8 / X20-10 Reset button (S102) X20-8 / X20-11 The auxiliary power on lamp for the slave cubicle has to be connected to terminal X20 according to the following table: Item Connection points White lamp (H101) X20-1 / X Precautions with capacitors Care must be taken while connecting the PQFL in parallel with a plain capacitor bank. For detailed, please refer to chapter 10 ( 2). 37

38 7. Master-slave interconnections 7.1. Introduction This section explains how to connect PQF sections (Master-Slave or Slave-Slave) when they do not come connected from the factory or in case of on-site extension. The section starts with mechanical installation. Electrical connections are then described: interconnections between sections and with the supply. All cables needed to make the connections are supplied with the units. A maximum of 4 power modules may be connected in parallel.!!!!!!!!!!!!!!!! Only modules of the same ratings may be paralleled!!!!!!!!!!!!!!!!!!!!!!! 7.2. Mechanical installation (cubicle version) The side panels of the cubicles to be interconnected have first to be removed (except the outside one of the Master and last Slave cubicles). The provided divider panel seal has to be fixed on the interior frame between cubicles. Cubicles are then interconnected at 6 fixation points as indicated in Figure 3.1. The baying kit is provided with the cubicles (not the tools). Figure 7.1. Mechanical installation 38

39 7.3. Electrical connections Connections between sections Power connection The DC bus of the master and slave sections must be connected. Each slave section comes from the factory with two cables connected on the + and - poles of the DC bus. Those cables are then fixed to the terminals of the DC bus of the next section. The cables must run away from the earth connection as far as possible. Be very careful about the polarity when connecting the DC bus. (Please refer to the enclosed photo.) Start the DC buses interconnection with the last slave and proceed similarly with each section until reaching the Master. An example of DC bus interconnection is given below (PQFT-master + 2 slaves) in Figure 7.2. Control + - Master Slave Slave Internal External connection to perform Figure 7.2. DC bus interconnection 39

40 Control connection The following terminals of the master unit and the first slave unit must be interconnected (three interconnections): Master Slave 1 A X21-1 connected to X21-8 B X21-2 connected to X20-2 C X21-3 connected to X21-7 D X21-4 connected to X21-6 The following terminals of the first slave unit and the second slave unit must be interconnected (three interconnections): Slave 1 Slave 2 A X21-1 connected to X21-8 B X21-2 connected to X20-2 C X21-3 connected to X21-7 D X21-4 connected to X21-6 The following terminals of the second slave unit and the third slave unit must be interconnected (three interconnections): Slave 2 Slave 3 A X21-1 connected to X21-8 B X21-2 connected to X20-2 C X21-3 connected to X21-7 D X21-4 connected to X21-6 The following terminals of the second slave unit and the third slave unit must be interconnected (three interconnections): Slave 2 Slave 3 A X21-1 connected to X21-8 B X21-2 connected to X20-2 C X21-3 connected to X21-7 D X21-4 connected to X Domino boards connection The inter-domino boards connection is achieved with flat cables. The flat cable must run as close as possible to the inside wall of the cubicle, close to the earthed part, away from the components. Each slave section is fitted with a loose flat cable. The other end of this flat cable has to be connected to the first plug of domino board A118 of the next cubicle, starting at the last slave. Make sure that the plug-in pattern of the connector and plug is respected. The last domino of the chain must be fitted with termination jumpers on positions JP100, JP101, JP102, JP103, JP104, JP105, JP106, JP109 and JP110 (JP107 and JP108 are off). An example of domino boards interconnection is given in Figure

41 Earth connection The earth cable of each slave cubicle has to be connected to the earth connection point of the master cubicle. Make sure that the cables run along the floor, not over components. The earth connection between master and slave shall be done using at least 16 sq.mm wire. The main earth connection (between the earth bar of each cubicle and the earth) shall be done in accordance with local electrical regulation Connections to the supply Power connection Four power cables (L1, L2, L3 and N) have to be connected to each busbar (one in each cubicle). The three phases are protected by fuses in each cubicle. Make sure that L1, L2 and L3 in each cubicle are connected to the same phases Protective earth The protective earth point of each cubicle has to be connected to earth. The connections to the supply are represented in Figure 7.3. Internal connection External connection to perform Control IGBT Module MASTER IGBT Module SLAVE 1 IGBT Module SLAVE 2 Domino A118 Domino A118 Domino A118 L1 L2 L3 N PE L1 L2 L3 N PE L1 L2 L3 N PE Figure 7.3. Flat cables connection and connections to power supply 41

42 8. PQF-Prog installation and PC connection The PQF-Prog, included in the standard PQFT package, allows for the complete programming of the filter. It consists of two Micro Floppy Disks delivered with the filter System requirements Windows NT 4.0 Service Pack 3 minimum. At least one free COM:port (RS232 - DB 9). One standard RS232 cable (male-female non twisted) 8.2. Installing PQF-Prog on your PC 1. Insert disk 1 of PQF-Prog in drive A 2. In the Start Menu, choose Run 3. In the Command Line box enter a:\setup 4. Follow the instructions in the dialog boxes to: Specify the drive and directory (c:\ Program Files \ Pqf is the default) Complete the installation 8.3. Hardware connection If your filter is equipped with the PQF-Manager, you just have to plug the DB 9 connection in the RS232 port situated at the front of the PQF-Manager. If your filter is not equipped with the PQF-Manager, you have to plug the connection in the RS232 port located on the control rack (A111: digital I/O board) as shown here after. RS232-port A111 A112 A113 A119 A114 A115 A116 U109 DIG INT DSP GUI LIC LVI ALIM/GND +5V RED LED GREEN LED YELLOW LED 42

43 9. Commissioning The commissioning of your PQFT should be conducted in strict accordance with the following procedure. Warning: Before applying the commissioning procedure, make sure that you become familiar with programming instructions (see chapter 10, programming with PQF-Prog and PQF-Manager). Pay particular attention to the presence of capacitors on the network. The commissioning procedure consists in 8 steps that should be followed very carefully. Step 1 Step 2 Step 3 Step 4 Step 5 Step 6 Step 7 Step 8 Installation check Voltage phase rotation Current transformer check System set-up Before starting the filter Start the filter Stop the filter Start filtering 9.1. Step 1 Step 1: Visual and installation check Check first that mechanical and electrical installations fulfil requirements described in chapter 4 and 5 of the present manual. Check also visually the conditions of the filter and the tightness of connections. In particular, verify that all connections on the control rack, domino board and IGBT are properly plugged in Step 2 Step 2: Voltage phase rotation Voltage phase rotation must be clockwise (L1 -> L2 -> L3 -> L1). Wrong phase rotation may damage the filter Step 3 Step 3: Current transformer check Improper CT connection is the most frequent cause of problems during commissioning. The following procedure will allow you to check the CT connection. Warning: The secondary circuit of a loaded CT must never be opened otherwise extremely high voltages may appear which can lead to physical danger or destruction of the CT itself. 43

44 PQF connection diagram Figure 9.1. shows the normal connection of the PQF. It must be noted that: L1, L2 and L3 rotation must be clockwise, The CTs must be on the supply (line) side of the PQF, One secondary terminal of the CT must be earthed. Supply side L1 L2 L3 N K k l L K k l L K k l L Load side L1 L2 L3 N X5.6 X5.5 X5.4 X5.3 X5.2 X5.1 PQF Figure 9.1. PQF connection It is also seen that terminal X5.1 and X5.2 are related to the CT located in phase L1, terminal X5.3 and X5.4 are related to the CT located in phase L2 and terminal X5.5 and X5.6 are related to the CT located in phase L Material needed & hypotheses for correct measurements A two channel scopemeter with one voltage input and one current input is needed. Adequate sensors are also needed. A power analyser like the Fluke 41B can also be used. Some minor knowledge of the load is also required. For instance, the method explained below is based on the fact that the load is inductive and not regenerative (i.e. the load current lags by less than 90 the phase voltage). If a capacitor bank is present, it is better to disconnect it before making measurements in order to ensure an inductive behaviour of the load. It is also assumed that the load is approximately balanced Checking the correct connection of the CTs with a two channel scopemeter. The first channel of the scopemeter must be connected to the phase voltage referenced to the neutral or to the ground if the neutral is not accessible. The second channel must measure the associated current flowing from the network to the load as seen by the CT input of the PQF Measurement of CT in phase L1 For the voltage measurement (channel 1), the positive (red) clamp must be connected to the phase L1 and the negative clamp (black) must be connected to the neutral (ground). For the current measurement (channel 2), the clamp should be inserted into the wire connected on terminal X5.1 and the arrow indicating positive direction of the current should point towards the PQF. Do not forget to remove the short on the CT secondary before making the measurement. 44

45 Supply side L1 L2 L3 N K k l L K k l L K k l L Load side L1 L2 L3 N X5.6 X5.5 X5.4 X5.3 X5.2 X5.1 PQF Positive direction Ch1 Ch2 Figure 9.2. Connection of the scopemeter for checking CT in phase L1. On the scopemeter screen, two waveforms should appear. The voltage waveform should be approximately a sine wave 1 and the current waveform would normally be a well distorted wave because of harmonic distortion. Usually, it is quite easy to extrapolate the fundamental component as it is the most important one (Figure 9.3). I I1 Figure 9.3. Extrapolation of fundmental component from a distorted waveform. From the fundamental component of both signals, the phase shift must then be evaluated (Figure 9.4). The time?t between zero crossing of the rising (falling) edge of both traces must be measured and converted to a phase shift? by the following formula: T φ = * 360 T 1 where T 1 is the fundamental period duration. For an inductive and non regenerative load, the current signal should lag the voltage by a phase shift lower than If the earthing of the system is bad, the phase to ground voltage may appear like a very distorted waveform. In this case, it is better to measure the phase to phase voltage (move the black clamp to the phase L2) and substract 30 on the measured phase shift. 45

46 U I1 T T1 Figure 9.4. Phase shift evaluation between two waveforms Measurement of CT in phase L2 and L3 The same operations as those described in the previous paragraph must be repeated with the phase L2 (Figure 9.5) and phase L3 (Figure 9.6). For a balanced load (which is usually the case in most of the three phase systems), the phase shift should be approximately the same for all the three phases. Supply side L1 L2 L3 N K k l L K k l L K k l L Load side L1 L2 L3 N Positive direction X5.6 X5.5 X5.4 X5.3 X5.2 X5.1 PQF Ch1 Ch2 Figure 9.5. Connection of the scopemeter for checking CT in phase L2. 46

47 Supply side L1 L2 L3 N K k l L K k l L K k l L Load side L1 L2 L3 N Positive direction X5.6 X5.5 X5.4 X5.3 X5.2 X5.1 PQF Ch1 Ch2 Figure 9.6. Connection of the scopemeter for checking CT in phase L Checking the correct connection of the CTs with two current probes. If the main bus bar is available and all security rules are taken, it is possible to use the two channel scope meter in order to see if the current measured through the CT is matching the real current in the bus. Connecting the current probes as shown on Figure 9.7., the two traces must be in phase and of the same shape (the magnitude could be different as the gain are different) if the wiring is correct. Positive direction Supply side L1 L2 L3 N K k l L K k l L K k l L Load side X5.6 X5.5 X5.4 X5.3 X5.2 X5.1 L1 L2 L3 PQF N Positive direction Ch1 Ch2 Figure 9.7. Connection of the scopemeter for checking CT in phase L1 by comparing the currents. This operation has to be repeated for the remaining two phases for a complete check. The current probes have to be changed accordingly. 47

48 Checking the correct connection of the CTs with a Fluke 41B. The Fluke 41B is a power analyser that allows measurements of one voltage and one current wave. Unfortunately, the device does not allow simultaneous display of both waveforms on the screen. But it is possible to synchronise the triggering on either the voltage or on the current. All phaseshift measurements are then referenced to the chosen origin. To read directly the phaseshift between the fundamental components, just select the spectrum window of the signal which is not chosen as the origin. The instrument must be configured in single phase measurements. The probes must be connected as shown on Figure 9.2, Figure 9.5 and Figure Step With PQF-Prog Step 4: System set-up Once the PQF-Prog software has been successfully installed and your PC is properly connected (see chapter 8), select Programs in the Start menu and click on PQF. If you did not install PQF-Prog in the Program Files directory, create a shortcut to PQF_Prog.exe. After launching PQF-Prog, a text box indicating that Station 0 has been found will appear. Click Done. You then enter the PQF-Prog main Window. In the Login box, type the User name and the password. Station must be 0. If you use the appropriate User name and password, four icons appear on the toolbar: Login, Filter Operation, Hardware set-up and Configuration. Configuration Login Hardware set-up Filter Operation 48

49 If a wrong or no login is entered, you will only have access to the Login, Filter Operation and Configuration icons. Click on the Hardware set-up icon. In the hardware set-up window, you will have to specify: Click on apply to validate. The network frequency The grid nominal voltage (phase to phase) The number of modules The three lines CT ratio With the PQF-Manager The 3 levels of the PQF-Manager are accessible from the window Main menu. To enter the Main menu window, press MENU. Level 1 is for consulting, level 2 for filter programming and level 3 for commissioning. Select level 3 by pressing once the? key. MAIN MENU Level 1 Level 2? Level 3? Then press OK and enter the appropriate password for level 3. The LED SET will switch on. In the hardware set-up window, you will have to specify: The network frequency The grid nominal voltage (phase to phase) The number of modules The three lines CT ratio 9.5. Step 5 Step 5: Before switching the filter on Before switching the filter ON, you have to ensure that all harmonics and reactive power compensation have been deselected. This can be done from the Filter Operation menu of the PQF-Prog or level 2 of the PQF- Manager. Please refer to the detailed programming instructions of chapter

50 9.6. Step 6 Step 6: Starting the filter With all harmonics and reactive power compensation deselected, you can start the filter by pushing the RUN button of the master cubicle. The main breaker should close within 30 seconds. One second after closing, the IGBT will start and the filter will work under no load condition Step 7 Step 7: Stop the filter Once the filter is connected to the network, stop it by pushing on the RESET button Step 8 Step 8: Start filtering Once you have checked that the filter can connect to the network, you may start filtering and reactive power compensation. After programming the filter according to the procedure of chapter 10, you can switch the filter on by pushing the RUN button. A start-up sequence will then be conducted. As represented on Figure 9.8, this sequence includes a network characterisation during which the filter may generated musical sounds. Start fan & preload DC bus Push RUN button Close MC Start-up sequence Start IGBT Network characterisation Operation as programmed Figure 9.8. Start-up sequence 50

51 10. Operation Normal working sequence After successful commissioning (refer to chapter 9), the procedure to operate the active filter is: 1. From the OFF position (auxiliary and main contactor open, no light on), switch on the auxiliary breaker. If your PQFT system has more than two modules, the auxiliary breaker of slave cubicles should be switched on before the one of the master cubicle. 2. After 20 seconds, the system will reset. 3. The auxiliaries are then on but the main contactor is still open. The white light (ON) and the green one (OPEN) of the master cubicle are on, while the green light (OPEN) of the slave cubicles is on. Master cubicle lights and buttons: RESET RUN LOC/REM ON CLOSE OPEN Slave cubicles lights: CLOSE OPEN If your PQFT is fitted with the PQF-Manager, the red LED POWER is on. 51

52 4. Push the RUN button located on the master cubicle. RESET RUN LOC/REM ON CLOSE OPEN 5. The filter then starts the start-up sequence: - Start fan and preload DC bus - Close main contactor - Start IGBT - Network characterization During the start-up sequence, the red LED START-UP of the PQF-Manager is on. Once the main contactor is closed, the red light (CLOSED) of the master and slave cubicles becomes on, while the green light (OPEN) switches off. Master cubicle RESET RUN LOC/REM ON CLOSE OPEN Slave cubicles: CLOSE OPEN LED n 3 of board A111 on the control rack should be red: it indicates that the PQF is properly synchronized to the network (see illustration next page). 52

53 6. After the start-up sequence, the PQFT operates as programmed. The red LED OK of the PQF-Manager should be on. In the LED FULL LOAD appears to be on, it only means that the filter cannot achieved the programmed requirements. Refer to the chapter on programming with the PQF-Manager for more information. A111 A112 A113 A119 A114 A115 A116 U100 U109 DIG INT DSP GUI LIC LVI ALIM/GND ±15V +5V RED LED GREEN LED YELLOW LED 7. Pushing the button RESET of the master cubicle causes the main contactor to open and to come back at step 3 of this procedure. RESET RUN LOC/REM ON CLOSE OPEN The normal working sequence is represented on Figure

54 OFF Switch on auxiliary breaker (Q101) 20sec. Time delay System reset Auxiliaries ON Push RUN button Start fan & preload DC bus Close MC Start-up sequence Start IGBT Network characterisation Operation as programmed Push RESET button Open MC Figure Normal working sequence 54

55 10.2. Additional installation instructions for the PQFT in presence of plain capacitors In some installations plain capacitors (without detuning reactors) coexist with harmonic producing loads. This situation is unadvicable given that the harmonics impose a very high stress on the capacitors as a result of which their lifetime is greatly reduced. Moreover, due to the resonance condition created (by the capacitor and the predominantly inductive transformer and line impedance) high voltage distortion may be introduced which can cause other equipment in the plant to malfunction. Also the resonance amplifies the harmonic current created by the loads as a result of which the feeders and transformers may be overloaded. For these reasons ABB generally proposes to replace the plain capacitor by a detuned capacitor bank when high harmonic stress is present in the network. In some active filter applications the commissioning engineer is faced with an installation where both an active filter and plain capacitors are present. While this is an unadvicable and a technically unsound situation, ABB has acknowledged that in this case also the active filter should aim to give an optimal performance. For this reason the control software of the filter incorporates a Stability Detection Program (SDP) that aims to increase the filter performance in this type of applications. In installations where plain capacitors are present and cannot be changed to detuned capacitor banks, adhere to the recommendations below for optimal results: - Try to implement the installation given in Fig as opposed to the installation given in Fig Feeding transformer Filter CTs Plain capacitor bank PQFx Linear and non-linear loads Fig Proposed connection diagram for PQFx and plain capacitors. Feeding transformer Filter CTs PQFx Linear and non-linear loads Plain capacitor bank Fig Alternative for Fig when that connection approach cannot be implemented. In Fig. 10.2, the capacitor bank is connected between the transformer and the filter CTs as a result of which the filter measures the pure load current. In Fig the filter measures also the capacitor bank current. While in the case of Fig the SDP will also work, it will be slightly less efficient since the influence of the capacitors will be spread over a much wider frequency bandwidth. Harmonic filtering in the affected bandwidth may be interrupted more often for parameter optimisation, this leading to a less optimal filtering performance. Ensure that the filter is in Mode 3 (see chapter 10, 5) Behavior in case of power outage In case of power outage, the PQFT will stop and automatically re-start after having re-conducted the network characterisation and synchronization procedures. 55

56 10.4. Buttons, lights and LED s signification Master cubicle. RESET RUN LOC/REM ON CLOSE OPEN Push buttons: RUN: starts the PQFT RESET: stops switching of the IGBTs and opens the main contactor. Local remote switch: local or remote control of the filter. If remote is on, the push buttons are not operational. Lights: ON (white): the PQFT controller is connected to the supply (auxiliary breaker closed) CLOSE (red): the main contactor is closed (filter working) OPEN (green): the main contactor is open Three light conditions are then possible: No power connection (main contactor and auxiliary breaker open) Controller connected (auxiliary breaker closed, main contactor open) Filter working (aux. breaker and contactor closed) ON (white) CLOSE (red) OPEN (green) Slave cubicle CLOSE OPEN Lights: CLOSE (red): the main contactor is closed (filter working) OPEN (green): the main contactor is open 56

57 PQF-Manager Red LED s: POWER: the controller is connected to the supply (auxiliary breaker closed). START-UP: the PQFT is in the start-up sequence. OK: the PQFT is working properly and fulfilling programmed requirements. FULL LOAD: the filter is working at 100% of its nominal capacity and programmed requirements are not fulfilled. ALARM: the filter has stopped due to an error. SET: the programming or set-up level of the PQF-Manager has been activated. The PQF-Manager is also fitted with a screw to adjust contrast. This screw is situated on the back metal plate of the PQF-Manager Control rack. Board A111 DIG Board A112 INT Board A113 DSP Board A114 LIC Board A115 LVI LED 1 (green) on: OK LED 2 (red) on: malfunction LED 3 (red) on: PQF synchronised on network LED 1 (green) on: OK LED 2 (red) on: malfunction LED 1 (green) and LED 3 (yellow) blinking: OK LED 2 (red) on: malfunction LED 1 (green) on: OK LED 2 (red) on: malfunction LED 1 (green) on: OK LED 2 (red) on: malfunction 57

58 Board U109 LED 1 (green) on: OK LED 2 (red) on: power supply inhibited LED 3 (red) on: output 1 inhibited A111 A112 A113 A119 A114 A115 A116 U100 U109 DIG INT DSP GUI LIC LVI ALIM/GND ±15V +5V RED LED GREEN LED YELLOW LED Programming with PQF-Prog Filter operation principle. The filter can have three types of effect on the network: Filter the selected harmonics until their magnitudes are close to zero (Maximum Filtering); Filter the selected harmonics until their magnitudes reach the residual level permitted by the user (Filtering to Curve); Produce or absorb reactive power. The user can put the emphasis on one of the above effects by selecting the filtering mode. The following table shows the three available modes: Highest priority level Lowest priority level Mode 1 Filtering to curve Maximum filtering Reactive compensation Mode 2 Filtering to curve Reactive compensation Maximum filtering Mode 3 Filtering to curve Reactive compensation 58

59 In Mode 1, the PQFT will first filter to the pre-programmed curve. Once the requirements are fulfilled, remaining resources will be allocated to reducing the selected harmonics as close as possible to zero. If further resources are then available, reactive power compensation will be performed as required. In Mode 2, the second priority after filtering to the curve is reactive power compensation. Maximum filtering comes in third place. In Mode 3, two levels are defined: filtering to curve and reactive power compensation. In any case, filtering to curve is always the first priority. The alarm contact is activated (open) if the filtering to curve requirements are not fulfilled. Figure 10. here after illustrates the principle of filtering to curve for one particular harmonic order. The flexibility of the PQFT control is such that a specific curve may be defined for each selected harmonic. Before filtering After filtering Filtered current Load current for harmonic order n Permitted residual level = curve Remaining current Figure Filtering to curve for harmonic order n The programming procedure consists in: 1) Defining the Mode of operation. 2) Specifying the harmonics to be filtered and the permitted residual level (=curve) for each of them. At 50 Hz, 20 harmonics between the 2 nd and 50 th may be selected. At 60 Hz, 15 harmonics between the 2 nd and 50 th. 3) Programming reactive power compensation parameters Starting Once the PQF-Prog software has been successfully installed (see chapter 7), select Programs in the Start menu and click on PQF. If you did not install PQF-Prog in the Program Files directory, create a shortcut to PQF_Prog.exe. After launching PQF-Prog, a text box indicating that Station 0 has been found will appear. Click Done. You then enter the PQF-Prog main Window. 59

60 In the Login box, type the User name and the password. Station must be 0. If you use the appropriate User name and password, four icons appear on the toolbar: Login, Filter Operation, Hardware set-up and Configuration. Configuration Login Hardware set-up Filter Operation If a wrong or no login is entered, you will only have access to the Login, Filter Operation and Configuration icons. 60

61 Programming the filter Step 1: click on the Filter Operation icon. Step 2: Select the Filter Mode tab. Step 3: Select the option button corresponding to your chosen mode of operation. The priorities of the selected mode are indicated at the bottom of the window. Click on Ok if you wish to save your choice and leave the Filter Operation mode. Click on Apply if you wish to validate your choice and stay in Filter Operation mode. Step 4: Select the Harmonics tab. In order to select a harmonic order, enter Y (yes) in the second column. N (no) indicates that the corresponding harmonic has not been selected. The curve may be programmed in absolute terms (Amps), in % of the fundamental current or in % of the rms current. After choosing your appropriate reference by using the option button, program your target in the third column for the harmonics you have selected. The values there entered constitute the curve and the first priority of your PQFT will be to filter harmonics until each selected order becomes lower than its specified target. Click on Ok if you wish to save your choice and leave the Filter Operation mode. Click on Apply if you wish to validate your choice and stay in Filter Operation mode. 61

62 Step 5: The filter may be switched on or off from the On/off tab Programming with PQF-Manager Filter operation principle. The filter can have three types of effect on the network: Filter the selected harmonics until their magnitudes are close to zero (Maximum Filtering); Filter the selected harmonics until their magnitudes reach the residual level permitted by the user (Filtering to Curve); Produce or absorb reactive power. The user can put the emphasis on one of the above effects by selecting the filtering mode. The following table shows the three available modes: Highest priority level Lowest priority level Mode 1 Filtering to curve Maximum filtering Reactive compensation Mode 2 Filtering to curve Reactive compensation Maximum filtering Mode 3 Filtering to curve Reactive compensation In Mode 1, the PQFT will first filter to the pre-programmed curve. Once the requirements are fulfilled, remaining resources will be allocated to reducing the selected harmonics as close as possible to zero. If further resources are then available, reactive power compensation will be performed as required. In Mode 2, the second priority after filtering to the curve is reactive power compensation. Maximum filtering comes in third place. In Mode 3, two levels are defined: filtering to curve and reactive power compensation. In any case, filtering to curve is always the first priority. The alarm contact is activated (open) if the filtering to curve requirements are not fulfilled. 62