Control and modulation strategies for MMC - based HVDC
Author
Haddioui, Marcos Rejas
Term
4. term
Education
Publication year
2015
Submitted on
2015-05-27
Pages
92
Abstract
Modulære multilevel-konvertere (MMC) er en nyere konvertertopologi, som har ændret brugen af VSC-HVDC (spændingskildekonverter-baseret højspændingsjævnstrøm) til eltransmission. Disse systemer flytter strøm over meget lange afstande og sammenkobler AC-net, der ikke er synkrone. Fordi en MMC består af mange distribuerede effektelektroniske enheder, er styringen af, hvordan afbryderne tændes og slukkes (modulationen), udfordrende. Dette speciale gennemgår eksisterende modulationsmetoder og foreslår forbedringer, der skal: holde kondensatorspændinger i balance, sænke koblingsfrekvensen og fordele effekttab mere jævnt mellem afbryderne. Vi sammenligner flere modulationsmetoder ved forskellige konvertereffekter, herunder en lille prototype og et HVDC-system, for at vurdere ydeevne. Til sidst er der designet og bygget en lille prototype for at bekræfte simuleringsresultaterne.
Modular Multilevel Converters (MMCs) are a newer converter design that has transformed voltage-source converter high-voltage direct-current (VSC-HVDC) transmission. These systems carry electricity over very long distances and connect AC grids that are not synchronized. Because an MMC is made up of many distributed power-electronic units, controlling how its switches turn on and off (the modulation) is challenging. This thesis reviews existing modulation techniques and proposes improvements that: keep capacitor voltages balanced, reduce switching frequency, and distribute power losses more evenly across the switches. We compare several modulation methods at different converter power ratings, including a small-scale prototype and an HVDC system, to assess performance. Finally, a small-scale prototype is designed and built to validate the simulation results.
[This abstract was generated with the help of AI]
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