避免高补偿度线路直流偏置风险的断路器合闸控制方法

断路器在关合带并联电抗器的空载线路时,尤其线路补偿度较高或过补偿时,合闸电流的直流分量较大,常伴有合闸电流长时间不过零的现象。在电流不过零期间若断路器分断,则会产生无法灭弧的风险。针对上述问题,在对直流偏置电流产生的原理及可能引发故障进行分析的基础上,比较和分析了装设合闸电阻、调整补偿度、相位控制等抑制直流偏置的常规措施及其局限性,提出了一种结合选相合闸技术及逐相动态延迟合闸的断路器合闸控制方法,有效避免了断路器触头持续长时间烧蚀或损坏的风险,并通过实时数字仿真系统(RTDS)和工程应用验证了该方法的有效性。

Control method of circuit breaker to avoid DC offset risk in closing transmission lines with high level of compensation

DC offset in current of circuit breaker is non-ignorable during transmission lines energizing with shunt reactors, especially when transmission lines have a high level of compensation or overcompensated. In most cases, there is a long time without any zero-crossing point of current when energizing, and it will cause arc extinction problem for the circuit breaker if there is a trip operation. Based on the principle of DC offset generation and the failure risks of circuit breakers caused by DC offset, conventional measures to suppress DC offset are discussed,which include addtion of closing resistors for the circuit breaker, reducing compensation degree and controlled closing. A method which combine the controlled closing technology and dynamic delay closing for each phase are proposed, then the risk can be successfully eliminated during transmission lines energizing. The effectiveness of above method is validated by RTDS simulation and field test on several transmission lines.