串联电感限制变电站二次系统电缆中地电位升干扰的研究

Study on Limitation of GPR Caused Interference in the Cables of Substation Secondary System by Using Series Inductance

变电站的工频磁场感应、接地故障地电位升高(ground potential rise,GPR)和雷电GPR能够在二次系统的电缆中产生显著的寄生电流,同时在电缆两端的端口产生信号干扰,导致二次系统故障和损坏。提出一种限制变电站二次系统电缆中寄生电流和端口信号干扰的方法,将电缆的部分长度缠绕在磁环上,形成电感,将具有此电感的电缆连接于二次设备之间,电感可减小通过电缆的寄生电流和电缆端口的干扰电压,但对电缆传输信号的性能没有影响。建立模拟变电站接地故障的试验电路,以验证该方法的有效性。

Parasitic current could be produced in the cables of substation secondary system due to the power frequency magnetic field induction, the ground potential rising （GPR） resulting from ground fault and the GPR resulting from lightning current, and at the same time, electromagnetic interference can be produced at the ports on both ends of the cables, which will result in failure and damage of secondary system. A method for limitation on the parasitic current in the cables and the interference at the cable ports is proposed. It is realized by winding part of the cable around a magnetic ring to form an inductance. The cable with the series inductance can reduce the parasitic current and the interference caused by GPR, and has no influence on the signal transmitting performance of the cable. Testing has been performed to simulate the substation＇s grounding fault and the effectiveness of the method bas been verified.