Impacts of Signal Filters’ Bandwidths on Small-signal Stability for Hybrid MMC

The hybrid modular multilevel converter (MMC) is promising in the application of over-head-line-based high-voltage-direct-current (HVDC) transmission. The bandwidths of signal filters for the control system may impose distinct impacts on small-signal stability. Based on the small-signal model, this paper investigates the impacts through root locus analysis and recognizes the critical bandwidths of every signal filter. The master or slave control modes as well as the inverter or rectifier operation status are comprehensively considered in the calculation. The eigenvalue studies are certificated by the detailed electromagnetic simulation. The results provide the useful suggestion for the selection of bandwidths to ensure stable operation.