串联谐振式限流器的仿真研究

Simulation study of series resonance type fault current limiter

串联谐振式限流器具有工作原理、拓扑结构简单等优点,且对于高压系统,其一次回路参数能够做到合理配置;但在电网发生短路故障进入短路限流工况过程中,其电容器及并联转换开关将工作在相当恶劣的条件下。应用Matlab软件对上述情况进行了建模仿真研究,得出如下结论:①闭合转换开关短接电容器使限流器从正常运行模式切换到短路限流模式过程中,将在电容与转换开关之间产生电压(电流)的高频振荡,且振荡电压(电流)的幅值与转换开关的动作速度成振荡增幅关系;②当转换开关采用功率半导体器件构成时,要求控制系统快速响应短路故障闭合转换开关,否则极易因振荡过流(过压)而损坏;③在限流器进入短路限流模式但继电保护尚未动作于断路器切断故障回路期间,转换开关将承受全部短路电流以及振荡电流,采用电力电子型转换开关时,其功率半导体器件的容量必须按这种工况进行选择。

The series resonance type fault current limiter has the advantages of simple operating principle and topological structure, etc. The primary parameter of series resonance type fault current limiter for high-voltage system is reasonable. However, in the process of restraining fault current after a fault occurrence in electrical network, the capacitor and parallel inverter switch will confront poor working condition. This paper studies the above condition by simulation using the software Matlab. Proceeding from the study, we arrive at the conclusions： 1 ） in the process of closing the inverter switch short circuit capacitor to make the current limiter work in short circuit current limiting mode switching from normal operation mode, there is higher-order of voltage （current） oscillation between capacitor and parallel inverter switch, and the peak value of voltage （current） increases and oscillates with the growing of the speed for closing the inverter switch; 2） when the inverter switch is composed of semiconductor device, control system must respond to short circuit and close the inverter switch quickly, otherwise, the semiconductor device may be damaged by over current （voltage） ; 3） during fault current limiter working in current limiting mode to short circuit loop being shut off by relay protection device, the inverter switch will bear the full fault current and oscillation current. If using semiconductor device as inverter switch, the capacity of semiconductor device must be chosen according to the working condition.