An analysis on the influence of interface inductor to STATCOM system with phase-shift control and corresponding design considerations

The design of the STATCOM interface inductor is very important. Previous publications regarding the design and specification of interface inductors for STATCOM usually deal with the interface inductor only, and seldom pay attention to the influence of interface inductor to STATCOM system performance. In this paper a detailed analysis on the interface inductor influence to STATCOM system and corresponding design consideration is presented. In STATCOM system, especially in high voltage and power situation, two basic control methods are used. One is phase-shift control, and the other is Phase and Amplitude Control (PAC). In this paper, the phase-shift control is considered as the STATCOM control strategy. First, the model of STATCOM is carried out. Second, the transfer functions are presented. Through frequency domain methods, such as transfer functions and Bode plots, the influence of interface inductor on the STATCOM system stability and filtering characteristics is extensively investigated. Third, based on the analysis, the design considerations for interface inductor are discussed, which leads to filter parameters different to traditional design. All the computer simulation results verified the validity of the above analysis and design.