Investigation of voltage regulation stability of static synchronous compensator in power system

This paper presents theoretical analysis and experimental verification of voltage regulation stability problems of static synchronous compensator (STATCOM). The basic application of STATCOM is to supply fast voltage support to the power system. Therefore maximum response rate of the voltage regulation loop is always expected. However, through theoretical analysis, digital simulation and experimental investigation on a real STATCOM model, it is found that the voltage regulator of STATCOM may tend to be unstable under some circumstances. The factors influencing the stability margin of the STATCOM voltage regulation loop include the strength of the power system viewed from STATCOM, the inherent resonance of power network the operation point of STATCOM, the synchronizing method and the load. All these aspects are described in details in this paper. To enhance the stability of STATCOM voltage regulating loop, this paper applies the phase compensation method to achieve larger phase margin of the control loop. The stability of the current regulation loop of STATCOM is also studied in this paper.