同塔双回直流融冰装置感应电压分析与应对措施

Analysis and countermeasures of induced voltage of double-circuit DC ice melting device on the same tower

±500 kV牛寨换流站为双回同址共建换流站,其输电线路部分区段双回同杆架设。2021年,一回直流运行、一回直流停运,牛寨站35 kV#1直流融冰装置对停运回直流线路地线开展融冰时,因运行回线路感应电压影响跳闸。根据统计分析及监视数据,受运行回线路等因素影响,停运回线路可产生100 kV以上感应电压,直接导致融冰装置解锁过程中跳闸,同时存在融冰设备受损风险。针对该问题,研究提出4种可行应对方案和措施,并评估确定最优方案,经现场实际验证能有效抑制停运回线路上的感应电压,满足融冰装置正常启动条件。同时,通过试验验证,确定运行回选择合理降压运行方式,可有效抑制停运回线路上的感应电压。

±500 kV niuzhai converter station is a double circuit co construction converter station at the same site,and some sections of its transmission line are erected on the same pole.In 2021,one circuit of DC operation and one circuit of DC shutdown.When the 35 kV#1 DC ice melting device of niuzhai station melts the ground wire of the shutdown DC line,it trips due to the influence of the induced voltage of the operation circuit.According to the statistical analysis and monitoring data,due to the influence of operating return circuit and other factors,the shutdown return circuit can produce an induced voltage of more than 100 kV,which directly leads to the tripping during the unlocking of the ice melting device,and there is a risk of damage to the ice melting equipment.To solve this problem,four feasible solutions and measures are proposed,and the optimal scheme is evaluated and determined.The field practice shows that it can effectively suppress the induced voltage on the shutdown return line and meet the normal starting conditions of the ice melting device.At the same time,through the test verification,it is determined that the reasonable step-down operation mode can effectively suppress the induced voltage on the shutdown circuit.