高压配电系统中电涌保护器保护距离软件仿真与实例研究

Software Simulation and Case Study of Protection Distance of Surge Protector in High Voltage Distribution System

针对目前关于电涌保护器(surge protective devices,SPDs)有效防护距离计算过程较为繁杂的问题,提出了在简化集总参数电路模型的基础上,利用电路原理讨论了不同负载条件下SPD保护距离的变化情况,并给出了SPD负载电压和保护距离的一般方程式。然后,通过软件仿真证明了该分析方法的正确性。最后,通过实例研究了一定长度电缆上测量不同负载下SPD和负载上的过电压,以及在不同长度电缆上测量相同负载下SPD和负载上的过电压,结果表明,在电阻负载的条件下,当其大于连接线特征阻抗时,负载电压会发生振荡和过冲,且电阻负载越大,SPD的有效保护距离越短;在无功负载的条件下,SPD的保护距离受线路电感L的影响较大;在电容负载条件下,负载电压的振荡最为剧烈,在该负载条件下的有效保护距离最小。

In view of the problem of surge protective device(SPDs)that the calculation process of effective protective distance is complicated at present,the variation of SPD protective distance under various load conditions is discussed on the basis of simplifying the lumped parameter circuit model and by the use of circuit principle,and general equation of SPD load voltage and protection distance is given.Then,the correctness of the analysis method is proved through software simulation.Finally,the over voltage of SPD and load under different loads is measured on a certain length of cable and the over voltage of SPD and load under same load is measured on a different length of cable.The result shows that under the condition of resistance load,when resistive load exceeds the characteristic impedance of connection line,the load voltage will occur oscillation and overshoot.The larger the resistive load is,the shorter the effective protection distance of SPD is.In case of reactive power load condition,the protection distance of SPD is greatly affected by the line inductance L.While,in case of capacitive load,the oscillation of the load voltage is the most severe and the effective protection distance is minimum at this load condition.