Transformer modelling for studying the propagation of partial discharge pulses

Abstract

A computer model developed for studying the propagation of partial discharge (PD) pulses in a continuous disc type 6.6 kV transformer winding is described in the paper. The winding model takes the turn as the basis for the analysis and uses multi-conductor transmission line theory to obtain a system of equations to calculate the voltage and current along the winding. Capacitance, inductance, resistance and conductance are calculated as distributed parameters for the winding model. Transfer functions that can be used to study the effect on the PD current as the monitoring point moves from the location of the PD to the line-end and the neutral-end are calculated. The transfer functions represent the frequency response of the signals measured at the line and neutral-end terminals for a PD pulse represented by a Dirac delta function at the point of discharge. The zeros of the transfer functions convey information about the position of the discharge and hence can be used for its location.