经过渡电阻短路接地故障的计算方法研究

Study on calculation methods of ground fault through transition resistance

对经过渡电阻短路接地故障的计算方法进行了研究,用对称分量法分析了单回线经过渡电阻接地故障,以及用六序分量法分析参数完全对称的同杆双回线经过渡电阻接地故障。针对不对称参数同杆双回线经过渡电阻接地故障进行分析:用对称分量法将线路阻抗矩阵分解为正序、负序、零序,得出两回线的正序量、负序量之间没有耦合,只有零序量之间存在耦合的结论;借鉴六序分量法中把电流分解为同向量和反向量的思路,将存在耦合的零序分解为零序同向量和零序反向量。再分别对新解耦方法各序的系统阻抗进行修正。用新的解耦方法进行故障分析,给出了新序网中过渡电阻的修正系数,并与PSCAD仿真结果进行对比,从而验证了新解耦方法的正确性。

The calculation methods of ground fault through transition resistance are studied. Firstly, single-line ground fault through transition resistance is analyzed by symmetrical component method. The six-sequence component theory is used to analyze two parallel lines on the same tower when the parameters are exactly the same. Secondly, a method is presented to analyze two parallel lines of asymmetry parameter on the same tower. According to symmetrical component method, impedance matrix of the lines is decoupled to positive sequence, negative sequence and zero sequence. It comes to a conclusion that positive sequence and negative sequence have already been decoupled, but zero sequence is still coupling. Then, the coupling zero sequence is decoupled to the same directional zero component and the circumfluence zero component based on six sequence component theory in which the zero sequence is divided into the same directional component and the circumfluence component. And system impedance is modified. Finally, the new decoupling method is applied to do fault analysis and figure up the correction coefficient of transition resistance. The PSCAD results prove that the new decouoline method is correct.