BS EN 62751-2:2014
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Power losses in voltage sourced converter (VSC) valves for high-voltage direct current (HVDC) systems – Modular multilevel converters
| Published By | Publication Date | Number of Pages |
| BSI | 2014 | 58 |
IEC 62751-2:2014 gives the detailed method to be adopted for calculating the power losses in the valves for an HVDC system based on the “modular multi-level converter”, where each valve in the converter consists of a number of self-contained, two-terminal controllable voltage sources connected in series. It is applicable both for the cases where each modular cell uses only a single turn-off semiconductor device in each switch position, and the case where each switch position consists of a number of turn-off semiconductor devices in series (topology also referred to as “cascaded two-level converter”). The main formulae are given for the two-level “half-bridge” configuration but guidance is also given as to how to extend the results to certain other types of MMC building block configuration.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 4 | Foreword Endorsement notice |
| 5 | Annex ZA (normative) Normative references to international publications with their corresponding European publications |
| 6 | English CONTENTS |
| 9 | 1 Scope 2 Normative references 3 Terms, definitions, symbols and abbreviated terms |
| 10 | 3.1 Terms and definitions |
| 11 | 3.2 Symbols and abbreviated terms 3.2.1 Valve and simulation data |
| 12 | 3.2.2 Semiconductor device characteristics 3.2.3 Other component characteristics 3.2.4 Operating parameters |
| 13 | 3.2.5 Loss parameters 4 General conditions 4.1 General |
| 14 | 4.2 Principles for loss determination 4.3 Categories of valve losses |
| 15 | 4.4 Loss calculation method 4.5 Input parameters 4.5.1 General 4.5.2 Input data for numerical simulations |
| 16 | 4.5.3 Input data coming from numerical simulations 4.5.4 Converter station data |
| 17 | 4.5.5 Operating conditions 5 Conduction losses 5.1 General Figures Figure 1 – Two basic versions of MMC building block designs |
| 18 | 5.2 IGBT conduction losses Figure 2 – Conduction paths in MMC building blocks |
| 19 | 5.3 Diode conduction losses |
| 20 | 5.4 Other conduction losses |
| 21 | 6 DC voltage-dependent losses 7 Losses in d.c. capacitors of the valve |
| 22 | 8 Switching losses 8.1 General 8.2 IGBT switching losses |
| 23 | 8.3 Diode switching losses 9 Other losses 9.1 Snubber circuit losses |
| 24 | 9.2 Valve electronics power consumption 9.2.1 General |
| 25 | 9.2.2 Power supply from off-state voltage across each IGBT 9.2.3 Power supply from the d.c. capacitor |
| 26 | 10 Total valve losses per HVDC substation |
| 27 | Tables Table 1 – Contributions to valve losses in different operating modes |
| 28 | Annex A (informative) Description of power loss mechanisms in MMC valves A.1 Introduction to MMC Converter topology |
| 29 | Figure A.1 – Phase unit of the modular multi-level converter (MMC) in basic half-bridge, two-level arrangement, with submodules |
| 30 | Figure A.2 – Phase unit of the cascaded two-level converter (CTL) in half-bridge form |
| 31 | A.2 Valve voltage and current stresses A.2.1 Simplified analysis with voltage and current in phase Figure A.3 – Basic operation of the MMC converters |
| 32 | A.2.2 Generalised analysis with voltage and current out of phase Figure A.4 – MMC converters showing composition of valve current |
| 33 | A.2.3 Effects of third harmonic injection Figure A.5 – Phasor diagram showing a.c. system voltage, converter a.c. voltage and converter a.c. current |
| 34 | A.3 Conduction losses in MMC building blocks A.3.1 Description of conduction paths Figure A.6 – Effect of 3rd harmonic injection on converter voltage and current |
| 35 | Figure A.7 – Two functionally equivalent variants of a “half-bridge”, two-level MMC building block |
| 36 | Figure A.8 – Conducting states in “half-bridge”, two-level MMC building block |
| 37 | Figure A.9 – Typical patterns of conduction for inverter operation (left) and rectifier operation (right) |
| 38 | Figure A.10 – Example of converter with only one MMC building block per valve to illustrate switching behaviour Figure A.11 – Inverter operation example of switching events |
| 39 | Figure A.12 – Rectifier operation example of switching events |
| 40 | A.3.2 Conduction losses in semiconductors |
| 41 | Figure A.13 – Valve current and mean rectified valve current |
| 44 | A.3.3 MMC building block d.c. capacitor losses A.3.4 Other conduction losses A.4 Switching losses A.4.1 Description of state changes Table A.1 – Hard switching events |
| 45 | Figure A.14 – IGBT and diode switching energy as a function of collector current |
| 46 | A.4.2 Analysis of state changes during cycle A.4.3 Worked example of switching losses Table A.2 – Soft switching events |
| 47 | Figure A.15 – Valve voltage, current and switching behaviour for a hypothetical MMC valve consisting of 5 submodules |
| 48 | Table A.3 – Summary of switching events from Figure A.15 |
| 49 | A.5 Other losses A.5.1 Snubber losses A.5.2 DC voltage-dependent losses |
| 52 | A.5.3 Valve electronics power consumption Figure A.16 – Power supply from IGBT terminals |
| 53 | Figure A.17 – Power supply from IGBT terminals in cell |
| 54 | A.6 Application to other variants of valve A.6.1 General A.6.2 Two-level full-bridge MMC building block Figure A.18 – Power supply from d.c. capacitor in submodule Figure A.19 – One “full-bridge”, two-level MMC building block |
| 55 | A.6.3 Multi-level MMC building blocks |
| 56 | Figure A.20 – Four possible variants of three-level MMC building block |
| 57 | Bibliography |
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