柔性直流换流站短路工况下直流场磁场计算建模及预测分析

Modeling and Prediction Analysis of Magnetic Field in DC Yard of VSC-HVDC Station under Short Circuit Condition

对于安装有混合式直流断路器的柔性直流换流站,直流断路器分断故障电流速度快、内部换流时间短,由故障电流引发的磁场对直流场内二次设备的电磁影响尚不清楚。建立了混合式直流断路器分时段多路径的磁场计算模型,以及平波电抗器、直流母线的磁场计算模型,预测了直流侧发生双极短路故障时定海换流站和张北换流站直流场内二次设备处的磁场,获得了直流场磁场分布规律。计算结果表明:定海换流站和张北换流站直流场现有的二次设备处磁场强度峰值可能达到883A/m和362A/m;磁场强度峰值出现在故障电流达到峰值或直流断路器第二次换流阶段;直流场平波电抗器附近和母线布置较多的地方磁场较大。计算结果可为二次设备抗扰度考核和电气设备布置提供参考。

For the voltage source converter based high voltage direct current(VSC-HVDC)station equipped with hybrid DC breakers,the DC circuit breaker has fast speed for breaking fault current and short time for internal commutation.The electromagnetic influence of magnetic field caused by fault current on secondary equipment in DC field is not clear.A multi-path magnetic field calculation model of hybrid DC circuit breaker and a magnetic field calculation model of smoothing reactor and DC bus are established to predict the magnetic field around the secondary equipment in the DC field of Dinghai Converter Station and Zhangbei Converter Station with bipolar short circuit fault at the DC side,and the distribution characteristics of magnetic field in the DC yard is obtained.The calculation results show that the peak value of magnetic field intensity around the existing secondary equipment in the DC field of Dinghai Converter Station and Zhangbei Converter Station can reach 883 A/m and 362 A/m respectively;the peak value of magnetic field intensity occurs at the time when the fault current reaches its peak value or the DC breaker has the second commutation;the magnetic field intensity is higher near the smoothing reactor and at the location where there are many buses in the DC yard.The calculation results can provide a reference for the evaluation of secondary equipment immunity and the layout of electrical equipment.