Partial discharge propagation inside a high voltage transformer winding: Comparison of measurement and simulation

Partial discharge (PD) analysis, based on measurement data, assumes that PD signals propagate inside a transformer winding from the PD source to the measurement points. In this paper, signals are injected via an external connection into specific points along the winding of a transformer experimental model. The measurement data obtained using radio frequency current transducers (RFCT) connected to the external bushing tap and the neutral to earth connections are illustrative of the propagation of signals inside a transformer winding. Thus, this paper reports on the development of a simulation model based on a lumped parameter network approach and compares simulation results with experimental measurements of PD signal propagation inside a high voltage transformer winding model. The physical model is an interleaved disc type winding which consists of eight sections and is modeled as having internal winding series resistances (R), inductances (L), series capacitances (K) and shunt capacitances (Cg), the model also includes the effect of their mutual inductances. The parameters are calculated using analytical calculations based on geometrical dimensions and the winding is modeled using a commercially available mathematics package. The simulation creates PD signals at both ends of the winding i.e. at terminal 1 and terminal 8, which are grounded through a small capacitive and resistive element to represent the bushing end and neutral to earth connection respectively. An experiment has been developed that can be used to validate the simulation data and hence determine the accuracy of the derived model and ultimately its use as a PD localisation approach.