基于柔性限流器的直流配电网继电保护研究

Research on Relay Protection of DC Distribution Network Based on Flexible Current Limiter

为了提高直流配电网线路故障诊断能力,提高电路保护能力,提出多端柔性直流配电网继电保护策略,使用到的限流设备主要有MMC换流器、DC-DC换流器、直流断路器、故障限流器、直流钳压器和潮流控制器等。并对传统的潮流控制器进行改进,加入了故障限流和断路功能,利用模量分量进行解耦处理分析电气量特征,进行判断故障线路启动保护方案。仿真实验结果显示,该研究保护策略故障电流不超过6 kA,短路电流在0.005 s内快速低落到0,经过电流抑制后故障电流幅值降低了58.75%。

In order to improve the line fault diagnosis ability and circuit protection ability of DC distribution network,this study proposes a relay protection strategy for multi-terminal flexible DC distribution network.The current limiting devices used mainly include MMC converters,DC-DC converters,DC circuit breakers,fault current limiters,DC voltage clamps and power flow controllers,etc.The traditional power flow controller is improved,the fault current limiting and circuit breaking functions are added,and the modulus component is used for decoupling processing to analyze the characteristics of electrical quantities and to judge the fault line start protection scheme.The simulation results show that the fault current of the protection strategy in this study does not exceed 6kA,the short-circuit current rapidly drops to 0 within 0.005 s,and the fault current amplitude is reduced by 58.75%after current suppression.