Analysis on Control Stability of STATCOM Applied on Weak Power System

Abstract

Control stability when Multi-level STATCOM is applied on weak power system is discussed in this paper. In order to research the stability of weak system quantitatively, the current inner open-loop transfer function with system impedance is presented. Nyquist curve is used to demonstrate the relationship between the system impedance and the system control performance. Then a new control strategy - adding the current's proportion-differential (PD) to the feed forward voltage, is proposed. This control strategy can eliminate the positive feedback action caused by system impedance. Finally, test result proves that the above theoretical analysis is correct.