An Optimal Voltage Balancing Control Strategy for MMC-HVDC

Sub-module capacitor voltage balancing strategy is the research difficulty of MMC-HVDC project. Based on the quick sort voltage balancing strategy, an optimized sort strategy for submodule capacitor voltage balancing control is proposed. In this strategy, the sort process is divided into two parts by introducing a recursive threshold. When the number of sub-modules of the sequence is large, the quick sort voltage balancing strategy is adopted. When the recursion reaches the threshold, the sorting method is converted to the heap sort. Taking the back to back MMC-HVDC project connecting Chongqing and Hubei power grid as an example, the simulation results show that the proposed voltage balancing strategy can greatly improve the computation speed and effectively reduce the switching frequency of IGBT.