单相重合时序对750kV输电线路合闸过电压的影响

Influence of Time-Sequence of Single-Phase Autoreclosure on Switching-on Overvoltage Occurred in 750 kV Transmission Line

单相重合闸投入时序对750 kV输电线路的合闸过电压有较大影响,为此分别建立了无补偿线路和两端经并联电抗器补偿的750 kV输电线路的分布参数模型,推导出单相重合闸期间非全相运行时线路恢复电压和一侧单相重合后的稳态电压解析式,分析合闸过电压与系统容量、补偿度、线路长度等因素之间的关系,分析结果表明无论是无补偿还是经并补补偿后的线路,由大电源侧首先重合可降低单相重合过电压峰值。并据此从抑制合闸过电压角度提出了750kV输电线路的单相重合闸时序整定策略。仿真算例验证了重合时序整定策略的有效性。

The time-sequence of single-phase autoreclosure evidently influences the switching-on overvoltage occurred in 750 kV transmission line. To research this problem, two models with distributed parameters for 750 kV transmission line are built respectively： one is for the transmission line without compensator and the other is for the transmission line compensated by shunt reactors at both terminals; then two kinds of analytic expressions, one of which is for recovery voltage of transmission line under open-phase operation during single-phase autoreclosure and the other of which is for steady state voltage after the completion of single-phase autoreclosure at one terminal, are derived to analyze the relations between switching-on overvoltage and such factors as system capacity, degree of compensation and line length. Analysis results show that whether the transmission line is compensated or not, the autoreclosure first performed at the terminal connected to large power source can reduce the peak value of overvoltage caused by the single-phase autoreclosure. Based on this conclusion and from the viewpoint of suppressing switching-on overvoltage, a strategy to set the time-sequence of single-phase autoreclosure of 750 kV transmission line is proposed. The effectiveness of the proposed setting strategy for time-sequence of the single-phase autoreclosure is verified by results of PSCAD simulation.