平行双回线路单回线不对称故障时提取故障分量的新方法

Novel Fault Components Extraction Approach for Asymmetrical Fault on Double-Circuit Transmission Lines

针对传统的只能在故障后2到3个周波提取故障分量的缺点,提出了单回线不对称故障在整个故障过程提取故障分量的新方法.该方法在平行双回线路的六序故障分量理论和单回线不对称故障复合序网图的基础上,根据同向网正、负序电流分布系数相等和反向网正、负序电流分布系数相等的特点,用正、负序电流反向量和负序电流同向量间接求得正序电流同向量的故障分量,进而合成得到每回线各相电流的故障分量.该方法不受负荷电流和电网参数波动的影响.PSASP和MATLAB仿真表明,通过该方法得到的故障分量同实际故障分量相同,而且可以长时间提取.

Transverse differential current protection based on fault component has better performance compared with the conventional ones, for traditional fault component extraction approach can only satisfy the practical demand 2 or 3 cycles after fault inception. Since the coupling double-circuit transmission lines may be decomposed into decoupling the same directional component mode net and the circumfluent component mode net, the analysis demonstrates that the positive and negative sequence current distribution coefficient in the same directional component mode net coincides with that in the circumfluence component mode net, which motivates to propose a novel approach of fault component extraction. With the aid of the approach, the fault components are extracted correctly during the whole process without the influences of load components and network parameters. The digital simulation verifies its validity.