An analysis on the influence of interface inductor to STATCOM system with Phase and Amplitude Control and corresponding design considerations

Previous publications regarding the design and specification of interface inductor and DC side capacitor for STATCOM usually deal with the interface inductor and the DC side capacitor only, and seldom pay attention to the influences of interface inductor and DC side capacitor on STATCOM systems performance. Phase-shift Control and Phase and Amplitude Control (PAC) are two basic control methods. In this paper, the Phase and Amplitude Control is considered as the STATCOM control strategy. And, a detailed analysis on the influences of interface inductor and DC side capacitor on STATCOM systems and corresponding design consideration are presented. First, the models of the current loop and the voltage loop in STATCOM system by using two modeling methods are carried out. Second, the transfer functions of each control loop are presented. Through frequency domain methods, such as Bode plots, the influences of interface inductor and DC side capacitor on the STATCOM system stability are extensively investigated. Third, based on the analysis, the design considerations based on phase margin for interface inductor and DC side capacitor are discussed.