不对称参数同杆双回线选相方法研究

线路参数不对称的同杆双回线无法使用传统的六序分量法进行解耦。针对这个问题，提出一种新的解耦方法。首先，三相分解成正序、负序、零序分量；然后，耦合的零序分量进行解耦，分解为同向和反向分量。该方法解决了不对称参数同杆双回线的零序互感问题。当线路发生故障时，可以根据故障边界条件得到序分量之间的幅值和相位关系。不同线路发生故障时，两回线正序分量的电流幅值不同。同一回线发生不同类型的故障时，六序电流分量的幅值有对应的关系。同一类型的不同相发生故障时，六序分量的相位不同。根据上述关系提出了相应的选相判据，并给出了选相流程和方法。PSCAD仿真结果表明，该方法具有良好的选择性，且不受故障类型，故障位置以及过渡电阻的影响。

Research on phase selection for double-circuit lines on the same tower with asymmetrical parameters

Double-circuit lines on the same tower with asymmetrical parameters can not be decoupling with traditional six-sequence components. To solve this problem, a new decoupling method is proposed. Three phases are decomposed to positive, negative and zero sequence component first, but there are mutual inductance between zero sequence component. Then the zero sequence is divided into the same direction component and the reverse component. The method solves the problem of zero sequence mutual inductance of double circuit lines on the same tower with asymmetric parameters. When a line fault occurs, the relationship between the current components can be found out by the boundary conditions. If a fault occurs on different lines, the amplitudes of positive sequence components of two lines are different. If different kinds of fault occur on the same line, the amplitudes of six-sequence component have corresponding relation. If a fault occurs on different phases with the same types, the six-sequence component'' phase is different. This paper proposes relevant phase selection criterion according to the above relations, and also gives its procedure and method. PSCAD simulation results show that the method can accurately measure the phase of fault and is not affected by the type of fault, fault location, fault resistance.