同塔多回输电线路并联电抗器的参数优化分析

Parameter Optimization Analysis of Shunt Reactors for Multi-circuit Transmission Lines on the Same Tower

同塔多回输电线路间的电磁耦合使得并联电抗器与中性点小电抗的取值需重新优化。建立了同塔多回输电线路的分布参数耦合模型,得出潜供电流与弧道恢复电压的表达式,并可推广至多重故障情况;研究了影响潜供电流和恢复电压的关键因素。基于潜供电弧的动态模型,计算了电弧起始长度、中性点小电抗等对燃弧时间的影响,进而得到并联电抗器的取值准则,指出单回与多回线路中性点小电抗优化取值的差异之处。采用谐振频率分析法,综合考虑非全相运行、回路间电磁感应等引起的谐振过电压,导出了多回线路的固有谐振频率简化表达式,指出中性点小电抗的取值范围与取值方法。研究结果对超/特高压多回输电线路并联电抗器的优化设计具有指导价值。

The electromagnetic coupling between multicircuit transmission lines on the same tower necessitates optimization of the four-legged shunt reactors installed on them. This paper present the equations for calculating the secondary arc current as well as the recovery voltage through establishing general electromagnetic coupling model for multi-circuit transmission lines. The key factors influencing the secondary arc current and the recovery voltage were researched. A dynamic secondary arc model for ultra high voltage （UHV） transmission lines was built to investigate the impacts of the initial arc length, the neutral reactor on the arcing time of the secondary arc on multi-circuit transmission lines. Differences in optimal value of the neutral reactor of the four-legged shunt reactors between single-circuit and multi-circuit were discussed. Resonance frequency analysis was carded out regarding the resonant over-voltages caused by unbalanced switching operations as well as by electromagnetic induction between circuits. A simplified formula for calculating the inherent resonance points was deduced which indicated the range of the neutral reactor and also the method of its re-optimization that could be applied to the multi-circuit transmission lines. The results present useful reference for design of the four-legged shunt reactors on extra high voltage （EHV）/UHV multi-circuit transmission lines on the same tower.