MMC-HVDC Technology

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Table of contents

List of figures
List of tables
1 Introduction
1.1 Electrication History – The War of Currents
1.2 Today’s Incentives for HVDC Systems
1.3 Motivations behind Multi-Terminal HVDC Systems – Example of the North Sea
1.4 Objective of the Thesis and Main Contributions
1.5 Outline of the Thesis
1.6 List of Publications Derived from This Work
2 HVDC Systems State of the Art
2.1 Chapter Introduction
2.2 LCC-HVDC Technology
2.2.1 Components of LCC-HVDC
2.2.2 LCC-HVDC Congurations
2.3 VSC-HVDC Technology
2.3.1 Components of VSC-HVDC
2.3.2 Conguration and Operation of VSC-HVDC
2.3.3 Advantages of VSC-HVDC over LCC-HVDC
2.4 MMC-HVDC Technology
2.4.1 Components of MMC-based HVDC transmissions
2.4.2 Advantages of the MMC
2.5 Chapter Conclusion
3 Modelling and Control of VSC-based Converter Stations
3.1 Chapter Introduction
3.2 Modelling and Control of a VSC-HVDC Station
3.2.1 Modelling of the VSC
3.2.2 Control of the VSC
3.3 Modelling and Control of an MMC-HVDC Station
3.3.1 Modelling of the MMC
3.3.2 Control of the MMC
3.4 Chapter Conclusion
4 State-Space Representation and Modal Analysis of an HVDC Link
4.1 Chapter Introduction
4.2 State-Space Representation of the VSC Model
4.2.1 Linearisation of the VSC Model
4.2.2 State-Space Representation of the Linear VSC Model
4.2.3 Validation of the VSC Models
4.3 State-Space Representation of the MMC Model
4.3.1 Linearisation of the simplied MMC Model
4.3.2 State-Space Representation of the Linear MMC Model
4.3.3 Validation of the MMC Models
4.4 Modal Analyses of an HVDC Link
4.4.1 HVDC link with VSCs
4.4.2 HVDC link with MMCs
4.4.3 Comparison of the HVDC Systems
4.4.4 Comparison of two MMC-based HVDC Links with dierent Energy Control Strategies
4.5 Chapter Conclusion
5 SVD Analysis of a 5-Terminal MMC-Based MTDC System
5.1 Chapter Introduction
5.2 State-Space Representation of the MTDC System
5.2.1 Control Strategy of an MTDC System
5.2.2 State-Space Representation of the MTDC System
5.2.3 Modal Analysis of the 5-Terminal MTDC System
5.3 Singular Value Decomposition Analysis of the 5-Terminal MTDC System
5.3.1 Motivation Behind the SVD Tool
5.3.2 Design of the Voltage-Droop Gain using the SVD Tool
5.4 Impact of the DC Cable Model on the SVD Results
5.4.1 Wideband Model Reference
5.4.2 DC Cable Models Used in this Study
5.4.3 Comparison of the SVD Results for the 5 DC grid Models
5.5 Chapter Conclusion
6 A Frequency Droop Technique for the MTDC to Support AC Grid Frequency
6.1 Chapter Introduction
6.2 MTDC Systems to Support the AC grids Frequency Regulation
6.2.1 Proposition for a Frequency-Droop Controller
6.2.2 Voltage Droop and Frequency Droop: a Dual Controller
6.2.3 Interactions between Voltage and Frequency Droop
6.2.4 Correction of the Frequency-Droop Parameter
6.2.5 Impact of the Droop Controller Limits
6.3 EMT Simulations
6.3.1 Considered System
6.3.2 Eect of an AC Frequency Variation
6.3.3 Eect of an AC Frequency Variation when a Controller Reaches its Limit
6.4 Experimental Tests
6.4.1 Presentation of the L2EP Lille 5-Terminal Mock-up
6.4.2 Experimental Conditions
6.4.3 Experimental Results
6.5 Chapter Conclusion
7 Conclusions and Future Perspectives
7.1 Conclusions
7.2 Future Work
Bibliography
Appendix A Parameters or the HVDC Transmission Systems Used Throughout this Thesis
A.1 HVDC Link with VSCs
A.2 HVDC Link with MMCs
A.3 MTDC with VSCs
A.4 MTDC with MMCs
Appendix B Direct-Quadrature-Zero (or dq0) Transformation
Appendix C Controller Tuning
C.1 Inner Current Loops Controller Tuning
C.2 DC Voltage Loop Controller Tuning
Appendix D State-Space Association Routine
D.1 State-Space Association Theoretical Principle
D.2 Routine Methodology for State-Space Interconnection