Fast-transient repetitive controller based current control strategy for a cascaded DSTATCOM

Distribution STATic synchronous COMpensators (DSTATCOMs) have been proved an effective approach to correct power quality in distribution network. With reactive component and harmonic component of load current detected independently, selective compensation mode can be realized. To improve the reactive compensation ability and harmonic suppression performance of a cascaded DSTATCOM, the fast-transient repetitive controller (FREPC) was adopted for the design of compound current control strategy which consists of proportional integral (PI) inner loop and FREP outer loop. Theoretical analysis shows that the inherent delay of fast repetitive control is only one-sixth of traditional repetitive control, thus it owns a faster dynamic performance. The design method of control parameters in the compound current control strategy together with its stability analysis were presented in detail. Finally, Matlab/Simulink model of three-phase three-wire cascaded DSTATCOM was constructed with experiments carried out on DSTATCOM industrial prototype, both simulation and experimental results show the proposed method can ensure fast dynamic response, high steady accuracy for reactive and harmonic current compensation.