基于MMC的直流电网短路电流分析及保护策略

Short Circuit Current Analysis in DC Grid and its Protection Strategy Based on Modular Multilevel Converter

为解决基于MMC的直流电网短路电流问题,对半桥型MMC换流器以及具备直流故障自清除能力换流器的直流故障电流进行理论分析,并给出了短路电流计算方法。在此基础上对直流电网拓扑结构进行分类,给出直流电网中短路电流的计算方法。最后针对不同换流器和电网拓扑结构,给出了系统故障检测及故障保护方法。通过系统仿真验证了上述理论分析及短路电流计算结果的可靠性。

In order to solve the short-circuit current in DC grid based on MMC, this paper analyzes the DC fault current in both converters with half-bridge MMC and self-cleaning DC fault, and gives the short-circuit calculation method. On this basis, the DC grid topology is classified and the calculation method of the short-circuit current in the DC grid is given. Finally, the system fault detection and fault protection methods are given for different converters and grid topologies. The reliability of the above theoretical analysis and short-circuit current calculation result is verified by system simulation.