交流串入直流造成500kV主变压器无故障跳闸的分析及改进措施

介绍了500 kV某变电站由于设计错误造成交直流混用引起1号主变压器无故障跳闸的事故。通过对事故发生时情况的模拟,以及对主变压器出口继电器及其二次回路的检查,找到了事故的原因:由于交流量窜入直流控制回路引起中间出口继电器动作从而造成主变压器无故障跳闸。通过试验对事故进行了分析,并提出了提高开关操作箱出口继电器的动作功率,合理规范二次电缆的路径,在不影响保护性能的前提下增加某些可能引起误动的关键开入量的动作时间的预防措施。

Analysis on 500 kV Main Transformer Tripping Without Fault Caused by AC Flowing into DC Circuit and Its Improvement Measures

The tripping of No.1 main transformer without fault in a 500 kV substation is described as a result of design errors caused by a mix of AC and DC.Through the simulation of the accident situation,the out-tripping relay and its secondary circuit of main transformer are inspected,and the reasons are found,that is,the tripping of main transformer without fault caused by the action of intermediate out-tripping relay because of AC flowing into DC control loop.Through the test and analysis of the accident,the precautionary measures are proposed,that is,to improve the action power of out-tripping relay of switching operation box,to standardize the path of secondary cable reasonably,and to increase the action time of some key inputs which may cause malfunction without affecting the protection performance.