Study of the Impact of Switching Transient Overvoltages on Ferroresonance of CCVT in Series and Shunt Compensated Power Systems

Ferroresonance phenomenon (FP) in a coupling capacitor voltage transformer (CCVT) profoundly deforms the voltage waveform. Transient overvoltage due to transmission line switching, particularly in series and shunt compensated power systems, is one of the most important issues that increases the exposure level of the CCVT to FP. A probabilistic study focused on the impact of transient overvoltages on the FP in CCVT is conducted in this article. Through this framework, the behavior of different types of ferroresonance damping circuits (FDCs) is investigated. By investigating the effect of several factors such as switching instance and different fault types in the presence of series and shunt compensation in the power system, the probability density function of the CCVT primary (bus voltage) and secondary (CCVT output) voltage signals with/without different FDCs is obtained. A criterion based on total harmonic distortion, designed to identify and determine the severity of the FP, is also introduced. Simulation results confirm that overvoltages in a series and shunt compensated power system will enhance the vulnerability of the CCVT against FP.