一种新型固态短路限流器拓扑及其控制策略

A NOVEL TOPOLOGY OF SOLID STATE FAULT CURRENT LIMITER AND ITS CONTROL STRATEGY

介绍一种适用于中高压电网的新型固态短路故障限流器,正常工作时对线路几乎无影响;当故障发生时,旁路交流电抗器立即自动插入故障回路进行限流,检测到故障后将故障相桥路进行逆变。直流电抗器中的能量回馈电网,桥路尽快退出故障线路的运行,随后故障电流完全由旁路交流电抗器限制。新型限流器的固态器件和直流电抗参数不受电网允许的短路电流水平约束,所以可进行灵活优化设计。理论分析和单相固态限流器在三相系统中的仿真结果表明,整个单相桥路相当于过零点断开的开关,限流器不会引起附加振荡和过电压,控制方法简单,新型固态限流器具有良好特性,在电力系统中有深入研究和开发的意义。

A novel topology of the solid state fault current limiter (SSFCL) is presented for medium- and high-voltage electric network. In the normal operation condition, the limiter has no obvious effect on loads. When fault happens, the bypass AC reactor will insert the fault line automatically to limit the short circuit current;when the control circuit detects a short circuit fault, the solid state bridge in fault line works as a inverter and it will be closed as soon as possible, the fault current is fully limited by the bypass AC reactor subsequently. Because the parameters of the solid state devices and DC reactor are not determined by short circuit current rating of the network, its design can be flexible. The proposed single-phase SSFCL is numerically tested. It is shown that the single-phase bridge is closed at the current across zero just like as a soft-switch, and there is no oscillation as well as over-voltage excited by the SSFCL when the fault current is switched off. The control mode is facility and facile. It proved that the theoretical prediction and the current limiting performance are satisfactory for research and development.