不同电压等级部分耦合线路的单回线故障分析

由于建设时间的不同,因此输电系统中会出现不同电压等级部分耦合的输电线路。这种线路故障时,由于存在零序互感,给故障分析带来了难度。针对这一问题,将耦合部分的线路,先分别进行传统的序分量分解,得到完全解耦的正序分量、负序分量和存在耦合的零序分量;然后再借鉴六序分量法的思路,把零序分为同向量和反向量,对零序互感进一步解耦;最后,利用零序电流电压之间的关系,对非耦合部分进行阻抗修正。根据故障时的边界条件,研究了不同电压等级部分耦合线路的序分量特征,给出了发生单回线故障时的复合序网图,解决了不同电压等级部分耦合线路故障计算的复杂问题。PSCAD仿真结果表明,该方法非常适用于不同电压等级部分耦合线路的故障分析,且短路分析计算具有精确性、实用性和有效性。

Line Fault Analysis on Partial Coupling Lines at Different Voltage Levels

In a power transmission system, there may appear partially coupled lines at different voltage levels because of the difference in construction time. When faults occur with this kind of lines, the zero-sequence mutual inductance will make it difficult for fault analysis. To solve this problem, as is conventionally done, the partially coupled lines are first decoupled into completely decoupled positive and negative sequence components and the zero sequence component with coupling. Then, the zero sequence is divided into the same direction component and the circumfluent component according to the six sequence fault component theory for further decoupling zero sequence mutual inductance. Finally, by use of the relation between the zero sequence current and voltage, the parameters of the uncoupled part will be modified. Based on the boundary conditions of the faults, the characteristics of sequence components are studied and the related sequence networks of single line faults are presented for their role in solving the complicated problem of fault calculation of partially coupled lines at different voltage levels. PSCAD simulation results show that this method is appropriate for fault analysis on partially coupled lines at different voltage levels, and the short circuit analysis and calculation prove to be correct, practical and valid. This work is supported by National Nature Science Foundation of China (No. 51177066, No. 51377104).