The impact of grid negative sequence voltage to STATCOM and control

Industrial Static Synchronous Compensator (STATCOM) is typically applied at or near the load center to mitigate voltage fluctuation, flicker, phase unbalance, non-sine distortion or other load-related disturbance. Special attention is paid to the influence of grid negative sequence voltage to STATCOM current, the unbalance of grid voltage causes not only the AC current unbalance but also the DC voltage fluctuation. In order to let the inverter voltage contain the fundamental negative sequence component corresponding to the grid voltage, a new dual-loop control scheme is proposed to suppress the influence in this paper. The negative sequence voltage decomposition algorithm is also introduced. The validity of all analyses is verified by the simulation.