Ferro-Resonance Analysis of Capacitor Voltage Transformer with Fast Saturation Damper

With the increase in capacitor voltage transformer (CVT) operation life, CVT impedance changes, and the short-time switching of overhead lines, it is very easy to cause a transient oscillation accident in which a CVT participates, reduce the insulation level of a CVT, and even induce regional power grid oscillation and easily cause capacitor breakdown, after long-term operation with defects. In this paper, the whole power network, including the generator, power grid, and consumer, is modeled, and the theoretical model of the CVT ferro-resonance connected grid is built. The frequency spectrum analysis, and the measurements of resonance bus voltage and line voltage, were carried out to find the design method of a fast saturation damper (FSD) and its voltage-current characteristics that affect the vibration, based on theory and practice; this paper puts forward effective measures to reduce the resonance effect of a CVT in operation, and avoid the oscillation of the line and even the regional power grid system.