近年来在110 kV电缆线路中,发生多起断路器合闸时电缆接头爆炸的事故.文中选取一发生典型接头击穿故障的电缆线路,使用PSCAD建立了该电缆线路的电磁暂态仿真模型.由于该线路中间接头击穿故障发生在电缆充电后.因此文中仿真了空载合闸时的电磁暂态过程.首先计算了电缆线路各个接头处的线芯过电压,由于空载线路电容效应,各个接头处线芯过电压逐渐升高.应用傅里叶变换对过电压进行频率分析,线芯过电压中包含较多的1～2kHz的高频成分.其次对线路不同接头处的护层电压进行计算,可得电压最大值出现在靠近线路首端的接头护层处.与线芯过电压相比,空载合闸时的护层感应电压中含有大量的1～3 kHz、超过10 kHz的高频分量.最后改变护层交叉互联与单端接地的联结方式,计算可得各处护层电压出现较大变化,最大护层电压有所上升.改变2种护层联结方式的顺序后,其对应的接头护层处电压的高频成分含量也出现变化.由于大量的高压单芯电缆护层采用混合联结方式,因此文中的研究结果对优化电缆护层的配置方式具有指导意义.%In recent years,quite a few of breakdowns of cable joints occurred due to closing of circuit breakers in the 110 kV cable line.In this paper,one cable line with typical fault is modeled using PSCAD/EMTDC.Since the breakdown occurs upon line energizing,the transient behavior under the condition of line energizing (no-load closing) is studied.First,the overvoltage on the cable conductor is calculated.Due to the capacity effect,the overvoltage of the cable conductor at each joint rises gradually.Fourier Transform is used for the frequency analysis of energization overvoltage and the result suggests that the cable conductor overvoltage contains more high-frequency components of 1 kHz to 2 kHz.Second,with the calculation of sheath voltage in each joint,it is found that the maximal voltage exists at the joint near the head of the line.Besides,compared with the cable conductor overvoltage,the induced voltage on the sheath with no-load closing contains a large amount of high frequency components of 1 kHz to 3 kHz,even above 10 kHz.Moreover,it is also found that sheath voltage as well as its high-frequency components vary heavily with the use of another configuration of cable sheath.Since complex configurations of metallic sheath are mostly adopted by single-core cables,the research results have significant guiding values for optimizing the configuration of cable sheath.
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