MMC-HVDC直流侧故障分析

针对MMC-HVDC经常出现且棘手的直流侧故障问题，分析了多电平模块化换流站（Modular Multilevel Conventer，MMC）的运行原理及工作特性，提出了采用子模块均压控制和相间环流抑制的适用于MMC的直流输电系统，并设计了相应的控制器；在MATLAB/SIMULINK环境下建立仿真模型，然后对MMC-HVDC直流侧单极接地、双极短路、断线故障仿真，仿真结果说明：所提出的控制策略能够保证系统在发生故障后维持稳定，提升了MMC-HVDC直流输电系统解决故障的能力；最后展望了更合适的故障保护措施及过电流抑制方法，对解决直流侧故障具有很重要的指导作用。

Fault Analysis for MMC-HVDC DC Side

In view of frequent and serious DC side fault problems of MMC-HVDC, this paper analyzes the operating principle and working characteristics of modular multilevel converter (MMC), proposes that sub-module voltage equalization control and inter-phase circulation suppression can better fit for MMC DC transmission system, and designs the corresponding controllers. A simulation model is constructed in MATLAB/SIMULINK environment, then the simulation is conducted on MMC-HVDC DC side single-pole grounding, bipolar short circuit, and broken-line fault, and the simulation results show that the proposed control strategy can ensure the system to maintain stability after the failure, and improve the ability to solve the fault in MMC-HVDC DC transmission system. Finally, more suitable fault protection measures and over-current suppression methods are prospected, which have important guidance for solving DC side faults.