Sensitivity Improvement of Acoustic Partial Discharge Detection Measurements through Wavelet Analysis

Abstract

<p>Condition monitoring of power equipment is a vital step<br />in extending the lifetime of existing equipment and<br />reducing costs for utilities while minimizing the risk of<br />unscheduled outages. Partial discharge (PD) monitoring<br />has evolved as a reliable mean of determining<br />deterioration in insulation systems. Acoustic emission<br />detection techniques are usually utilized for PD<br />detection mainly in oil-filled transformers offering the<br />advantage of being immune to electrical noise and a<br />method to localize PDs. In this work it was attempted to<br />improve the sensitivity of acoustic measurements<br />through wavelet analysis and estimation of the threshold<br />value from actual measurements of the noise, which<br />proved to be more effective compared to other<br />estimation values. The analysis was performed on<br />laboratory measurements from a 36 kV condenser<br />bushing known to exhibit PD activity acquired with a<br />low cost PD acoustic sensor developed at KTH. As a<br />next step the results have to be verified by online<br />measurements, which can result in the addition of an</p><p>Condition monitoring of power equipment is a vital step in extending the lifetime of existing equipment and reducing costs for utilities while minimizing the risk of unscheduled outages. Partial discharge (PD) monitoring has evolved as a reliable mean of determining deterioration in insulation systems. Acoustic emission detection techniques are usually utilized for PD detection mainly in oil-filled transformers offering the advantage of being immune to electrical noise and a method to localize PDs. In this work it was attempted to improve the sensitivity of acoustic measurements through wavelet analysis and estimation of the threshold value from actual measurements of the noise, which proved to be more effective compared to other estimation values. The analysis was performed on laboratory measurements from a 36 kV condenser bushing known to exhibit PD activity acquired with a low cost PD acoustic sensor developed at KTH. As a next step the results have to be verified by online measurements, which can result in the addition of an onboard signal-processing box for improved sensitivity.</p>