Stability improving of an MMC distributed system based on instability risk and capacitor voltage balancing capability evaluation

Compared with the traditional centralized control strategies, the distributed control strategies improve the flexibility and expandability of an MMC. The stability issue of the MMC distributed control system is rarely discussed in previous papers. This paper aims to improve the stability of a MMC distributed control system, by evaluating the instability risk and the capacitor voltage balancing capability of capacitor voltage control loops. Based on the theoretical analysis, a design principle is proposed to guide the control parameter design for capacitor voltage control loops, in order to guarantee the stable operation of the MMC. The rationality of the theoretical analysis and the correctness of the control parameter design principle are verified by experiment results.