Controlled-Impedance-Source-Based Distributed Control Method for Modular Multilevel Converter

Communication requirement is one of main considered aspects for modular multilevel converter (MMC) control system design, especially with considerable submodules (SMs). In this paper, a distributed control method for MMC based on controlled-impedance-source is proposed. By controlling SMs as adjustable impedance sources, grid synchronization and SM synchronization are achieved in local controllers (LCs). The central controller (CC) regulates the output voltage of MMC and sends a non-real-time impedance adjustment signal to all LCs. Without transmitting real-time synchronization signal, the communication requirement of the proposed control method is significantly reduced. Meanwhile, highly modularized, simple, and easy to implement are the hallmarks of the proposed method. The feasibility of the proposed method is validated by simulation results.