GIS中电子式电压互感器的VFTO抑制方法研究

Study on VFTO suppressing method for electronic voltage transformer in gas insulated substation

针对GIS中隔离开关操作产生的特快速暂态过电压(VFTO)导致有源电子式互感器采集卡损坏的问题,提出了一种新的VFTO抑制措施。首先研究电子式互感器中电容分压器的幅频特性,并推导出有源电子式互感器在高频条件下的分压比,通过计算得到作用于电子式互感器二次侧采集卡上的过电压幅值。进一步提出了在电子式互感器的电容分压器上插入同轴金属圆柱筒的方法,提高了电容分压器高频分压比,降低了VFTO的二次侧输出电压值。仿真结果表明,该方法大幅降低了VFTO作用于采集卡上的过电压,从而对采集卡形成保护,提高了电子式互感器运行的稳定性。

Affected by the very fast transient overvoltage（ VFTO）,the acquisition card of active electronic voltage transformer in the gas insulated substation（ GIS） might be damaged while the circuit breaker is being operated. In order to solve this problem,a new impedance suppressing method for the electronic voltage transformer has been proposed in this paper. Through amplitude-frequency characteristic analysis,we deduced the amplitude of very fast transient overvoltage for the electronic acquisition card,and the multilayer coaxial capacitors in parallel structure is proposed to increase the capacitance of low voltage arm capacitor,which also increases high frequency voltage division ratio and effectively suppresses the VFTO secondary overvoltage. Finally,the simulation results show that the method can significantly reduce the VFTO secondary voltage output,thus it protects the collector from high voltage and improves operating stability of electronic transformer.