Circular Array of Ultrasonic Sensor based DOA estimation: Location of multiple Partial Discharge in Transformer oil

Location of Partial Discharge (PD) in transformers is very important, and many methodologies that have been carried forward in previous decades have a restriction theoretically, specially, in power transformers they cannot locate multiple PDs. Based on array signal processing a novel multiple partial discharges localization is presented in this paper. Ultrasonic signal emission occurs when the partial discharge occurs inside the transformer oil tank. Using ultrasonic sensor arrays located on the wall of the transformer tank, emitted ultrasonic signals is detected. Generally a single partial discharge will not occur in transformer there may be multiple partial discharge occur at different location. For detection of multiple partial discharges, we have used circular array of ultrasonic sensors (CAUS) in our proposed method. Primarily, by using Translation Invariant Wavelet Transform the partial discharge signals are de noised. To change the wide-band signal received by CAUS to the narrowband one Total Least Square algorithm is utilized. After this, the number of PD signals is estimated and to find the directions of arrival (DOA) of the signal sparse representation of array covariance vector technique is utilized. Lastly, on the basis of estimation of DOA position of PD source is detected with the help of optimization algorithm in order to find the exact coordinates of the PD source.