A New Application of Rogowski Coil Sensor for Partial Discharge Localization in Power Transformers

This article deals with a new high efficient and cost effective lattice-Rogowski-coil sensor for partial discharge monitoring of power transformers. The sensor is a thin flat-shape printed circuit board type Rogowski-coil, which can be installed on the internal surface of the transformer tank with minimum disturbance to the normal operation of the transformer. Thanks to the accurate and desirable geometry of the sensor, precise monitoring can be carried out. Also, it was designed to handle the common trade-off between the low resonant frequency and high mutual inductance. An experimental setup for measuring the lumped model parameters of the sensor is made and it is shown that the desired resonance frequency of approximately 10 MHz is obtained. In order to evaluate the performance of the sensor, a specially prepared distribution transformer (20 kV/0.4 kV, 500 kVA) was considered. Partial discharge calibration pulses were injected into different locations of the winding of this transformer, and the ability of the sensor was verified in defect localization. Moreover, the effects of some practical aspects, like the value of the terminating resistor of the proposed special Rogowski-coil, its distance from transformer winding as well as the capability of the extracted features from detected PD signals, on the accuracy of PD localization are studied.