变压器中性点接地方式对和应涌流产生的影响分析

和应涌流影响变压器的正常运行,目前认为将空载合闸变压器或运行变压器的中性点对地断开,是切断和应涌流通路,避免产生和应涌流的有效方法。通过仿真和试验研究,分析了变压器中性点接地状态对变压器和应涌流产生的影响,结果表明变压器的中性点断开并不能消除和应涌流的产生,而且运行变压器或空载合闸变压器中性点断开与否,一台变压器空载合闸,运行变压器中都有可能产生和应涌流,并且中性点在不同接地的不同组合状态下,运行变压器中产生的和应涌流是不相同的。

Effects of neutral earthing on the occurrence of sympathetic inrush in transformer

The sympathetic inrush is harmful to the operation of transformer. At present, it is well believed that cutting the passage of inrush is an effective way to avoid the occurrence of sympathetic inrush in transformer by opening the grounding switch at the neutral of operating transformer or energizing transformer. By the numerical simulation and the experiment to analyze the effect of neutral earthing on the occurrence of sympathetic, this paper verifies that whether the neutral of operating transformer or energizing transformer earthing or not, the sympathetic inrush may occur in operating transformer when a transformer energized in parallel or in series. Changing the situation of neutral earthing, the sympathetic inrush will be variable. It is pointed that opening the switch of neutral earthing cannot get rid of the sympathetic inrush and prevent the differential protection to mal-operate, which means that the neutral earthing is not necessary condition for the occurrence of sympathetic inrush in transformer. This project is supported by National Natural Science Foundation of China (No. 50507014) and Electrical Power Science and Technology Foundation of Xuji.