随着电力系统规模的不断扩大，以及交直流系统混联的加强，部分母线单相短路电流大于三相短路电流的现象时有发生，给设备选择带来困难。金沙江一期工程的溪洛渡左、向家坝电站电力通过两个±800 kV直流通道送往华东地区。由于电站汇集区域大机组多、换流变电容量大，并且换流站与周边500 kV电网电气联系紧密，造成换流站500 kV侧单相短路电流大于三相短路电流，且已接近或超过现有设备所能承受的最大遮断容量，需采取措施进行限制，以保证电网的安全运行。变压器中性点小电抗接地和调整系统运行方式是限制单相短路电流的有效措施。以金沙江一期工程为背景，经过详细的模拟计算，对比了两种方式限制短路电流的效果，并提出本工程可行的降低换流站500 kV侧单相短路电流的措施。% With the extension of power system and the enhancement of AC -DC system, the phenomena that the single -phase short-circuit current at some buses is larger than the three -phase short -circuit current will often occur, which makes the troubles in the device selection.The power from Xiluodu and Xiangjiaba hydroelectric power stations (the first-stage project of Jinsha River) is transported to eastern region of China by two ±800kV direct current channels.As the great number of large generating units in the hydropower collecting region , the high-capacity of convertor stations , and the close link of con-vertor stations with 500 kV grid around, the single-phase short-circuit current may be larger than the three -phase short-circuit current at 500 kV buses of convertor stations , even approaching or exceeding the maximum breaking capacity of the de -vices, which must be restricted by taking some measures to ensure the safe operation of power grid .The neutral point earthed via small reactance of transformer and adjusting the operation mode of power system are the effective measures to reduce the single-phase short-circuit current.According to the first-stage project of Jinsha River, a feasible measure of reducing the single-phase short-circuit current at 500 kV buses in convertor stations is presented through the detailed simulation calcula-tion and the comparison between two different measures of restricting the short -circuit current.
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