Analytical solution of serial ferroresonance triggered by circuit breaker operation in solidly grounded power grids

Abstract

Ferroresonance can be induced by Circuit Breaker (CB) switching operations in neutral point solidly grounded power grids with matching parameters. No complete time domain analytical solution of ferroresonance has been developed in previous research, which is inconvenient for further analysis of this phenomenon. To solve this problem, a commonly accepted circuit model for Serial Ferroresonance (SF) in solidly grounded power grids is used and then validated. Piecewise linearization method is used to process the potential transformer nonlinear excitation inductance considering the gradual decrease of change rate of the characteristic B-H curve. Then the analytical solutions of the excitation inductance flux in underdamped and overdamped operation conditions are expressed. It is found that the response is composed of the steady-state component caused by system fundamental frequency excitation and the transient component determined by the initial energy storage of the system elements. Simulation is done to verify the analytical expression of SF, which lays the foundation for subsequent research on the analysis, detection, and suppression of ferroresonance.