Parameter Estimation of a Ferro-Resonance Damping Circuit using Pseudo-Random Impulse Sequence Perturbations

A parallel damping arrangement is typically included on the secondary side of a capacitor voltage transformer to improve the measurement accuracy and transient response. The damping arrangement, however, can affect the frequency and transient response of the capacitor voltage transformer. This paper investigates the use of a pseudo-random impulse sequence as a perturbation signal to estimate the model parameters of a passive capacitor voltage transformer damping arrangement. Transfer functions describing the damping arrangement are derived and are used to determine the observability of the circuit. The pseudo-random impulse sequence perturbation signal is applied to the terminals of the damping system, and system responses are recorded and subsequently used to estimate the associated frequency responses. Estimated parameter values, obtained from both the time-domain and frequency-domain responses using the genetic algorithm, are presented. It is shown that the frequency responses obtained using the derived mathematical functions correlate closely with the estimated responses. The damping arrangement parameter values are also shown to be estimated with a high degree of accuracy when more that one transfer function is used in the parameter estimation procedure.