Transformer Internal Incipient Fault Simulations

Transformer fault detection and diagnosis is becoming more important due to the restructuring of the electric power industry. In this era of deregulation, loading transformers to their optimum capacity is becoming normal practice, which in turn applies high stresses on the insulation of the transformers and increases the probability of occurrence of internal incipient faults. Such faults can lead to a catastrophic failure and hence cause outages. Utilities and other entities in the electric power business are therefore exploring ways of detecting these faults in transformers in the incipient stage. Terminal values, primary and secondary currents and voltages, convey information that can be used to detect transformer incipient faults. In an effort to characterize the behavior of the terminal values of a transformer during internal incipient faults, computer models were developed. This paper briefly reviews the models and discusses simulation results obtained using SIMPLORER® software package. It also presents a discussion of the influence of model parameters on the terminal values and provides suggestions on tuning them appropriately to achieve simulation data for various incipient fault scenarios. Finally, the simulation methodology was verified by a field recording of a secondary winding incipient fault.