短导体并联下的三相电流不平衡机理分析

Analysis on Three-phase Current Unbalance Mechanism under Parallel Connection of Short Conductors

摘要:

针对电力系统中短导体并联引发的三相电流不平衡现象因缺乏标准规范约束给生产运维所带来的困扰，从阻抗参数差异角度揭示了短导体并联下三相电流不平衡的机理，指出其本质为并联回路间三相阻抗比例不匹配引起的分流差异，并通过四川电网典型案例（同塔双回、非同塔双回、混合组塔线路及开关场内部导体）进行了仿真研究。研究表明，通过调整相序排布或换相措施可有效改善电流平衡度。研究结果为短距离并联导体设计与运维提供了理论依据及实践参考，建议在并联导体规划中注重三相阻抗一致性或阻抗比例匹配。

Abstract:

Aiming at the troubles in production and operation brought by three phase current unbalance caused by the parallel connection of short conductors in power system due to the lack of standard specification constraints, the mechanism of three phase current unbalance mechanism under parallel connection of short conductors is revealed from the perspective of impedance parameter differences, and it is pointed out that the essence is the differences in current distribution caused by the mismatch in the ratio of three phase impedances in parallel circuits. The simulation research is carried out through the typical cases in Sichuan power grid, such as double circuit transmission line on the same tower, double circuit transmission line on separate towers, hybrid tower line and conductors inside the switchyard, and it shows that the current balance degree can be improved effectively through phase sequence adjustment or phase commutation measures. The research findings provide theoretical basis and practical references for the design and operation and maintenance of short distance parallel conductors. It is recommended to pay attention to the consistency of three phase impedance or the matching of impedance ratios in the planning of parallel conductors.