Wideband Modeling, Field Measurement, and Simulation of a 420-kV Variable Shunt Reactor

A 420-kV gapped-core five-legged variable shunt reactor is modeled in the frequency range 5 Hz-10 MHz based on frequency sweep measurements and curve fitting using rational functions. Comparison with time-domain measurements at reduced voltage shows that the model can accurately predict the transient behavior of the shunt reactor, both for impinging over-voltages and circuit-breaker transient recovery voltages. Among the observations is that mutual coupling between the phases leads to a beat phenomenon in the reactor voltage following disconnection. Representing the shunt reactor by an LC parallel circuit leads to unrealistic results for steep-fronted incoming waves and high-frequency oscillating overvoltages, and for the attenuation of the transient recovery voltage following disconnection.