750 kV输电线路保护与单相重合闸动作的研究

阐述了750kV输电线路的电容效应、互感效应以及合闸过电压的问题，指出单相接地故障时若采用三相重合闸将不可避免地产生较高过电压。指出了750kV输电线单相重合闸的应用前提是避免并联电抗器补偿给单相重合闸可能带来的谐振过电压问题，分析并提出了并联电抗器中性点小电抗的正确取值范围。针对并联电抗与线路电容之间的电磁振荡对故障断开相恢复电压的影响，研究了单相瞬时性故障恢复电压的拍频振荡特点，并提出了750kV输电线路的单相重合闸方案与重合过电压的抑制方法。

RESEARCH ON PROTECTIVE RELAYING AND SINGLE-PHASE RECLOSURE OF 750 kV TRANSMISSION LINE

This paper expounds the capacitive effect, asymmetric effect and over-voltage problems of 750 kV long-distance transmission line. Analysis indicates that three-phase reclosure will produce intolerably serious over-voltage at single-phase faults. Therefore single-phase reclosure is of beneficial to the stability of power system and the depression of over-voltage, which results in the failure of single-phase reclosure. Considering shunt reactors compensation may bring resonance over-voltage, the paper analyzes the application precondition of single-phase reclosure and the selection of neural reactor of shunt reactors. Based on the influence of electromagnetism oscillation between the shunt reactor and line capacitance, the paper investigates the beat frequency characters of recovery over-voltage in single-phase transient fault case. At last, a new single-phase reclosure scheme of 750 kV transmission line is proposed.