SINAMICS DCM. DC converter Application - 12-pulse parallel connection with decoupled interphase transformer. Introduction 1

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3 Introduction 1 Description of the application 2 SINAMICS DCM DC converter Application - 12-pulse parallel connection with decoupled interphase transformer Application Manual Commissioning 3 Dimensioning example 4 Symbols 5 Literature 6 05/2017 A5E AQ/RS-AA/001

4 Legal information Warning notice system This manual contains notices you have to observe in order to ensure your personal safety, as well as to prevent damage to property. The notices referring to your personal safety are highlighted in the manual by a safety alert symbol, notices referring only to property damage have no safety alert symbol. These notices shown below are graded according to the degree of danger. DANGER indicates that death or severe personal injury will result if proper precautions are not taken. WARNING indicates that death or severe personal injury may result if proper precautions are not taken. CAUTION indicates that minor personal injury can result if proper precautions are not taken. NOTICE indicates that property damage can result if proper precautions are not taken. If more than one degree of danger is present, the warning notice representing the highest degree of danger will be used. A notice warning of injury to persons with a safety alert symbol may also include a warning relating to property damage. Qualified Personnel The product/system described in this documentation may be operated only by personnel qualified for the specific task in accordance with the relevant documentation, in particular its warning notices and safety instructions. Qualified personnel are those who, based on their training and experience, are capable of identifying risks and avoiding potential hazards when working with these products/systems. Proper use of Siemens products Note the following: Trademarks WARNING Siemens products may only be used for the applications described in the catalog and in the relevant technical documentation. If products and components from other manufacturers are used, these must be recommended or approved by Siemens. Proper transport, storage, installation, assembly, commissioning, operation and maintenance are required to ensure that the products operate safely and without any problems. The permissible ambient conditions must be complied with. The information in the relevant documentation must be observed. All names identified by are registered trademarks of Siemens AG. The remaining trademarks in this publication may be trademarks whose use by third parties for their own purposes could violate the rights of the owner. Disclaimer of Liability We have reviewed the contents of this publication to ensure consistency with the hardware and software described. Since variance cannot be precluded entirely, we cannot guarantee full consistency. However, the information in this publication is reviewed regularly and any necessary corrections are included in subsequent editions. Siemens AG Division Process Industries and Drives Postfach NÜRNBERG GERMANY A5E AQ/RS-AA/001 P 08/2017 Subject to change Copyright Siemens AG All rights reserved

5 Table of contents 1 Introduction Important note Preliminary remarks Description of the application Infeed transformer Converters Interface transformer Current transformer Drive motor/load Actual value sensing of the load voltage Commissioning Current control optimization Test Dimensioning example Symbols Literature Application Manual, 05/2017, A5E AQ/RS-AA/001 5

6 Table of contents 6 Application Manual, 05/2017, A5E AQ/RS-AA/001

7 Introduction Important note The application is provided are not binding and do not claim to be complete regarding configuration, parameterization or any eventuality which may arise. The dimensioning example does not represent a customer-specific solution and is only intended to provide assistance with typical applications. The company operating the system is responsible for the correct operation of the dimensioned systems. SIEMENS reserves the right to make changes and revisions to this document at any time without prior notice. If there are any differences between the suggestions made in this document and other Siemens publications, such as catalogs, the contents of the other document(s) take priority. 1.2 Preliminary remarks The 12-pulse converter circuit with interphase transformer is suitable for applications where solutions based on individual reactors are not feasible. The interface transformer acts to compensate the current in the direction of the load; as a consequence, when using an ideal interface transformer, the load current is hardly smoothed at all. Application Manual, 05/2017, A5E AQ/RS-AA/001 7

8 Introduction 1.2 Preliminary remarks 8 Application Manual, 05/2017, A5E AQ/RS-AA/001

9 Description of the application 2 The basis for the application with interphase transformer should be taken from application document "12-pulse applications 09/2015", Reference [1]. This defines the basic interconnection and parameterization. When dimensioning the individual components, the notes provided in this Chapter as well as in Chapter 4 (Page 15) should be observed. Application Manual, 05/2017, A5E AQ/RS-AA/001 9

10 Description of the application Figure 2-1 Overview of the armature circuit with relevant signals Legend Position Element 1 Supply transformer (see Chapter 2.1) 2 Converter (see Chapter 2.2) 3 Converter (see Chapter 2.2) 4 Interphase transformer (see Chapter 2.3) 5 Current transformer (see Chapter 2.4). 6 Drive motor / load (see Chapter 2.5). 7 Setpoint channel 8 Parallel connection interface 9 Actual load voltage 10 Actual load current 11 Actual value sensing, load voltage 10 Application Manual, 05/2017, A5E AQ/RS-AA/001

11 Description of the application 2.1 Infeed transformer 2.1 Infeed transformer 3-winding transformer or a group comprising 2 transformers. Phase of the secondary voltage shifted through 30 el. - possible vector groups are Dd0y11, Dd0y5, Yy0d11, Yy0d5. Identical nominal secondary voltages Short-circuit voltage, primary-secondary uk1-2 and uk1-3 should be at least 4 %. Not complying with this requirement can be compensated by installing commutating reactors between the transformer and the individual converters, according to the engineering specifications [2]. The short-circuit voltage - taking into account the reactance of any commutation reactors - should not exceed 12%, referred to the rated converter current. As far as possible, the same short-circuit voltage, primary-secondary for both secondary sides, uk1-2 and uk1-3. Deviations of up to 10% with reference to the particular values are permissible (e.g. maximum deviation uk1-2 = 3.6 % and uk1-3 = 4.4 %). The minimum short-circuit voltage between secondary windings uk2-3 should be higher than 10 %. A lower level of decoupling between the two systems could result in instability in the current distribution between the two system halves. 2.2 Converters These converters belong to the SINAMICS DCM series of devices. The application document involves typical applications for the selected devices; essentially, all SINAMICS DCM devices can be used. 2.3 Interface transformer The interface transformer is implemented as single-phase transformer. Ratio 1:1 Frequency = 600% line frequency (300Hz at 50Hz system, 360Hz at 60Hz system) The no-load current I0 should be 5-12% of the rated current. The value of the no-load current is to be achieved using the air gap in the interphase transformer core. The primary/secondary voltage is the U1_N = U2_N - is 0.65 times the line to line voltage of the secondary side of the infeed transformer. The rated thermal currents I1_N = I2_N of the windings correspond to half the DC output current of the system. The nominal power rating of interphase transformer SN* is 0.12x the nominal power rating of the current transformer. The short-circuit voltage uk of the interphase transformer should, as a minimum, be 10% - when considered as a transformer. A higher short-circuit voltage results in better current smoothing - and increases the line harmonics. Application Manual, 05/2017, A5E AQ/RS-AA/001 11

12 Description of the application 2.4 Current transformer In addition to increasing the no-load current, the air gap in the interphase transformer also results in achieving a lower sensitivity of the interphase transformer with respect to saturation effects when both converters are operating unbalanced. Reducing - or even eliminating - the air gap in the interphase transformer core reduces the no-load current, and therefore increases the effect of the interphase transformer when it comes to improving the system line harmonics. However, it should be noted that reducing the airgap increases the sensitivity of the interphase transformer regarding saturation. If the no-load current of the interphase transformer is to lie below 10%, for each % (percentage point) below 10%, the nominal power rating should be increased by a factor of 1.1. The precise dimensioning of the short-circuit voltage uk (or leakage inductance) and the noload current (or magnetizing inductance) of the interphase transformer depends on the specific application. In addition, additional data is required, for example load inductance, permissible current ripple, control dynamic response required etc. The requirements relating to permissible line harmonics (current and voltage harmonics) as well as the existing harmonic line distortion of other possible loads should also be clearly specified. Based on this data, a precise numerical transient simulation can be performed to determine the dispersion parameters of the interphase transformer. If, as a result of the simulation, leakage inductance variables (or short-circuit voltage uk) are obtained that cannot be implemented in practice, then the system is not suitable for the use of an interphase transformer. In this case, the better solution is to equip each converter with individual reactors. 2.4 Current transformer We recommend that a suitable current transformer is used at the output to sense the current actual value. The current actual value should be connected to one of the analog inputs of the CUD provided for the purpose, see FP6850, FP2085, FP2090 as well as parameters p81852, p81853 (master and slave) according to the List Manual [3]. 2.5 Drive motor/load The criteria listed are applicable for motor and/or resistive-inductive loads - including a counter voltage - with either no non linearity, or just a small amount of non linearity. A precise numerical simulation of the system is required if the system is to be designed/dimensioned for loads that are strongly non linear - or for capacitive loads. 2.6 Actual value sensing of the load voltage Sensing the actual voltage using a suitable voltage transformer (PT) at the load is necessary to achieve stability in operation, if the electromotoric voltage is parameterized as input variable of the precontrol. The voltage actual value should be connected to AI2 of the CUD (master and slave); the appropriate parameters must be assigned during the commissioning phase. See List Manual [3], function diagram FP6902, p51854, p Application Manual, 05/2017, A5E AQ/RS-AA/001

13 Commissioning 3 The system response depends on many parameters; it is not possible to draw up a parameter set that is generally applicable. As a consequence, it is absolutely essential that an experienced technician manually post-optimizes the current controller. 3.1 Current control optimization The current controller must be optimized according to the document 12-pulse applications 09/2015 [1] Chapter Test The notes and information provided in this document are recommendations. These are based on experience, state-of-the-art technology and numerical simulation. It must be carefully verified that dimensioning and parameterizing are correct. This must be performed in test operation, at the latest during the commissioning phase. Application Manual, 05/2017, A5E AQ/RS-AA/001 13

14 Commissioning 3.2 Test 14 Application Manual, 05/2017, A5E AQ/RS-AA/001

15 Dimensioning example 4 A motor with the following key data is involved: UN = 600 V IN = 4000 A After assessing the drive dynamic performance, line harmonics and other parameters, a decision was made to use a 12-pulse parallel circuit with the following data: U2N = 575 V 2x SINAMICS DCM converters, 4Q 575 V / 2800 A The infeed transformer is selected with the following key data: Transformer nominal power rating: SNT = U2N * 3* 2 / π * IN * 1.05 = 575 * 3* 2 / π * 4000 A * 1.05 SNT = 3.26 MVA U1 = according to the system supply point (point of connection) U2 = U3 = 575V Dd0y11 vector group uk1-2 = 5% uk1-3 = 5% uk2-3 = 15% Application Manual, 05/2017, A5E AQ/RS-AA/001 15

16 Dimensioning example The interphase transformer is defined as transformer: fn = 300Hz (6 50 Hz) Interphase transformer nominal power rating: SNIT = 0.12 * 3.26 MVA = kva U1 = 0.65 * 575V = 380V U2 = U1 = 380V I0 = 10% * kva/380 V = 51.5 A Thermal current of the winding I1 = 2000A Thermal current of the winding I2 = 2000A Short-circuit voltage of the interphase transformer uk = 15% This interphase transformer has an effective inductance per phase: The inductance values listed above can be measured between connections 1-3 or 2-3 The interface transformer described in the example mainly compensates the current in the direction of the load; as a consequence, when using this interphase transformer, the load current is hardly smoothed at all. 16 Application Manual, 05/2017, A5E AQ/RS-AA/001

17 Symbols 5 Symbol U1N, U2N I1N, I2N I0 uk1-2 uk1-3 Explanation Nominal primary/secondary voltage of the transformer Nominal primary/secondary voltage of the transformer Transformer no-load current Short-circuit voltage, secondary winding 2 with respect to the primary winding Short-circuit voltage, secondary winding 3 with respect to the primary winding uk2-3 Short-circuit voltage, secondary winding 2 with respect to secondary winding 3 uk Short-circuit voltage of the interphase transformer SNIT Nominal power rating of the interphase transformer, for dimensioning the interphase transformer, the nominal power rating with nominal core induction is considered. U1, U2 Rated voltages of the interphase transformer windings I1, I2 Rated currents of the interphase transformer windings SNT Type rating of the converter transformer Application Manual, 05/2017, A5E AQ/RS-AA/001 17

18 Symbols 18 Application Manual, 05/2017, A5E AQ/RS-AA/001

19 Literature 6 [1] Siemens AG; 12-pulse applications 09/2015; A5E G [2] Siemens AG; SINAMICS DCM, commutating reactors, operating instructions 2013; A5E A [3] Siemens AG; SINAMICS DCM List Manual, 6RX1800-0ED00 [4] Schäfer,J: Rectifier Circuits: Theory and Design, John Wiley&Sons Inc. USA, 1965; CatNo Application Manual, 05/2017, A5E AQ/RS-AA/001 19

20 Literature 20 Application Manual, 05/2017, A5E AQ/RS-AA/001

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22 Сименс Siemens АО AG Division Process Industries and Drives Postfach NÜRNBERG NUREMBERG GERMANY ГЕРМАНИЯ ALEMANIA GERMANIA ALLEMAGNE DEUTSCHLAND Возможны Sujeto Con Sous Änderungen Subject riserva réserve a to cambios change изменения di vorbehalten de modifiche modifications sin previo aviso techniques. 6RX1800-0AD27 6RX1800-0AD56 6RX1800-0AD78 6RX1800-0AD72 6RX1800-0AD77 6RX1800-0AD00 A5E AQ Siemens AG DC Converters SINAMICS DCM