【摘要】 模块化多电平换流器是柔性直流输电技术中的重要组成部分,柔性直流电网中直流过电压对整个系统的危害很大,因此对换流器闭锁退出运行后出现过电压进行仿真和机理分析。分析了换流器中子模块的6种工作状态和MMC的等效模型,根据换流站类型分为送端和受端换流站两种情况,基于PSCAD/EMTDC平台仿真换流器因故障闭锁后直流电压的变化情况,并根据等效电路分析换流站端口直流电压的动态发展过程和机理。由仿真结果发现,PSCAD/EMTDC仿真软件具有一定的缺陷,不能真实地反映断路器的断开,会产生虚拟过电压,并进一步分析了换流站闭锁后电压的变化趋势和产生原因。更多还原

【Abstract】 The modular multi-level converter is an important part of VSC-HVDC technology. The DC overv oltage in VSC-HVDC grid is very harmful to the whole system. Therefore, this paper analyzes the DC overvoltage mechanism of the converter block.Firstly, the six kinds of working state of sub-module are analyzed.Then, according to the types of converter stations, they are divided into sending and receiving ends. The change of DC voltage caused by blocked converter is simulated by PSCAD/EMTDC simulation software. The mechanism and dynamic process of DC voltage are analyzed in detail according to the equivalent circuit. Through the analysis of the simulation waveform, it is found that the PSCAD/EMTDC simulation software has some shortcomings, could not truly reflect the disconnection of circuit breakers, and generates virtual overvoltage. The reason and the trend of the changed DC voltage caused by blocked converter are summarized.更多还原