电容式电压互感器铁磁谐振抑制电路分析

Analysis of Two Kinds of Ferroresonance Suppression Circuits for Capacitor Voltage Transformer

从电容式电压互感器(CVT)的模型出发,分别研究了被动和主动型的铁磁谐振抑制电路(PFSC和AFSC)的消谐原理和它们对CVT的瞬态特性的影响。并结合实例研究了PFSC电抗值在不同负荷阻抗和频率条件下的灵敏度。通过AFSC电路的阻抗-频率函数式说明了它的理想阻抗-频率特性。仿真结果表明:AFSC优于PFSC之处在于:若CVT不含过电压保护设备,合理配置后的AFSC能快速减轻铁磁谐振。为了缩短PFSC谐振衰减时间,CVT系统需加装过电压保护设备;此外,铁磁谐振时,AFSC从SDT绕组引入谐振抑制回路的漏电流比PFSC小。

Starting from the capacitor voltage transformer （CVT） model, The harmonic elimination principle（PFSC and AFSC） of passive and active ferroresonance suppression circuits and its influence to the transient characteristics of CVT is studied respectively. The sensitivity of PFSC＇s reactance under different conditions of load impedance and frequency is studied combined with cases. The AFSC＇s ideal impedance-frequency characteristic is described by its impedance-frequency function. The simulation results show that： For which AFSC is superior to PFSC is that： if CVT does not contain the overvoltage protection device, the AFSC with reasonable configuration can reduce the ferroresonance quickly. In order to shorten decay time of ferroresonance in the circuits with PFSC, CVT system needs to install the overvoltage protection device; in addition, the leakage current from the SDT windings to ferroresonance suppression circuit by AFSC is smaller than PFSC when ferroresonance is happened.