Grid-Forming Control in STATCOM Applications
Dixit, Vikas Mohan (2024)
2024
Sähkötekniikan DI-ohjelma - Master's Programme in Electrical Engineering
Informaatioteknologian ja viestinnän tiedekunta - Faculty of Information Technology and Communication Sciences
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Hyväksymispäivämäärä
2024-05-15
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202405055305
https://urn.fi/URN:NBN:fi:tuni-202405055305
Tiivistelmä
A STATCOM (Static Synchronous Compensator) is a power electronics based device used in power system primarily for reactive power compensation and voltage control. Unlike conventional solutions, a STATCOM offers fast dynamic response and precise control. Traditionally, STATCOMs operate using phase-locked loop based grid-following control, relying on synchronous generators for voltage and frequency reference. However, with the rise of renewable energy, synchronous generators are gradually being replaced by converter-based power sources. Recently, researchers have started exploring grid-forming control as an effective control method for grid-connected converters in renewable energy-dominated grids.
This master’s thesis investigates grid forming control within the context of STAT COM control. Firstly, fundamentals of grid-following and grid-forming control are presented, followed by the development of simulations models for two grid-forming methods namely virtual synchronous machine control and virtual oscillator control. Further, aforesaid grid-forming methods are compared with grid-following control under strong and weak grid conditions. Finally, the thesis presents experimental implementation of grid-forming control.
The findings suggest that grid-forming control exhibits greater sensitivity to grid impedance variations compared to grid-following control. Additionally, grid-forming methods display higher coupling between active and reactive power in comparison to grid-following control. Furthermore, grid-forming control methods demonstrated the ability to autonomously establish and control system frequency, affecting rate of change of frequency significantly. However, DC source sizing emerges as critical in grid-forming STATCOMs, as small capacitor can negatively affect rate of change of frequency due to energy storage limitations.
This master’s thesis investigates grid forming control within the context of STAT COM control. Firstly, fundamentals of grid-following and grid-forming control are presented, followed by the development of simulations models for two grid-forming methods namely virtual synchronous machine control and virtual oscillator control. Further, aforesaid grid-forming methods are compared with grid-following control under strong and weak grid conditions. Finally, the thesis presents experimental implementation of grid-forming control.
The findings suggest that grid-forming control exhibits greater sensitivity to grid impedance variations compared to grid-following control. Additionally, grid-forming methods display higher coupling between active and reactive power in comparison to grid-following control. Furthermore, grid-forming control methods demonstrated the ability to autonomously establish and control system frequency, affecting rate of change of frequency significantly. However, DC source sizing emerges as critical in grid-forming STATCOMs, as small capacitor can negatively affect rate of change of frequency due to energy storage limitations.