Design, analysis and experimental evaluation of a virtual-synchronous-machine-based STATCOM with LCL filter

To address the generation uncertainty problems introduced by renewable energy power plants, STATCOMs are a typical solution to smoothen the point of common coupling (PCC) voltage in order to facilitate the integration of the renewables. A recently proposed control method - virtual synchronous machine (VSM), which controls grid-interfaced inverters to behave like synchronous machines so as to be more compatible with the existing power grid, has been applied to STATCOM and shows an improved performance over conventional D-Q frame based STATCOMs, along with tunable parameters that can be adjusted to different scenarios. In this paper, the idea is extended to a realistic STATCOM with LCL filter to mitigate harmonics and also some practical concerns about the active power compensation during transients, which is introduced uniquely by the VSM control method. Also a scaled down test bed is constructed to validate the control schemes.