面向超高压电网的故障限流器的应用研究

Application Research of Fault Current Limiter on the EHV Grid

针对迫切需要解决的大负荷中心短路电流超标的问题,在介绍了短路电流限制器研究现状,阐述了新型串联谐振型限流器(SCCL)工作原理后,用等面积法分析了单机无穷大系统中SCCL提高系统暂态稳定裕度的机理,并比较了串联电抗器与谐振型限流器的优缺点。谐振型参数设计是工程设计的难点,其中抑制因子代表着限流器限流能力,其取值要综合系统需求考虑。保证电容器可靠旁路是谐振型限流器的关键技术,多重化旁路开关技术能有效抵御电容器过压击穿的风险。基于优化参数的大量仿真实验证明:主电路设计合理,旁路开关电气强度降低,电容器在有效保护范围内。

This paper introduces recent researches about fauh current limiter （FCL）. Due to weakness of instability of many kinds of FCLs, they are not applied on the EHV. The series reactor is mostly used on the EHV for its stability, however, it adds power loss to the system, and specially, it decreases the system transient stability. Short circuit current limiter （SCCL） based on series resonance can avoid the disadvantages of the series reactor. This paper also analyzes how SCCL increases the transient stability by the equivalent square rule. It can decrease the acceleration square and increase system speed-down area. Resonance parameters design is the key point in the engineering design. If the restrain coefficient is too high, the power strength of SCCL would be challenged. To protect the capacitor to be safely switched is the key technology of SCCL for the voltage of the capacitor would be quickly increased when a fauh occurs. Multi-bypass breaker, which consists of MOV, thyristor, spark-gap and high speed breaker, can resist the disaster of the capacitor broken down by the overvolatage. MOV acts as the first line. SCR acts the second line. If SCR fails to act or delays much time, spark-gap would be triggered quickly, then high speed breaker closes up to endure bulk fault current. Thus the transmission line would not be interrupted by the capacitor breaking down. Based on the main circuit of SCCL, lots of simulation experiments are observed to find the effects of the resonance parameters. Through optimizing the parameters, SCCL gets good response to the fauh current and the capacitor is protected in the reasonable range.