基于疏松耦合变压器零序解耦模型的同杆双回线路故障计算

Fault Calculation Based on the Zero Sequence Decoupling Model of Loose Coupling Transformer for Double-circuit Lines

不并列运行的同杆双回输电线路在发生单回线不对称接地故障时,线路之间存在零序互感,在线路故障计算时必须予以考虑。文中提出疏松耦合变压器零序解耦模型,基于该模型对不并列运行同杆双回输电线路的零序网络进行解耦,得到线路等效回路,进而求得线路零序等值阻抗。在不并列运行的同杆双回输电线路故障分析中,利用传统的对称分量法,结合已求得的线路各序阻抗,计算故障处各序网络电流,进而得到故障情况下回路的各相电流,从而完成该型输电线路单回线故障的计算。PSCAD/EMTDC仿真结果证明了所提零序解耦模型的正确性。

There is zero sequence mutual inductance between the doublecircuit lines on the same tower without parallel operation when an asymmetric grounding fault occurred in single line, which should be considered in line fault calculation. In this paper, the zero sequence decoupling model of loose coupling transformer is proposed, based on which, zero sequence network of not parallel operation with parallel circuits on the same tower is decoupled to obtain the line equivalent circuit. Then the equivalent zero sequence impedance of the line is obtained. In the fault analysis of not parallel operation with double-circuit lines on the same tower, the traditional symmetrical component method is employed to calculate the sequence current where the fault is with the line sequence resistance obtained. And then the phase currents can be obtained, thereby completing the calculation of the single line fault. The zero sequence decoupling model proposed is verified by the result of PSCAD/EMTDC.