Partial Discharge Localisation in Power Transformer by UHF Technique

This article deals with the methods of finding partial discharge (PD) location in power transformers using ultra high frequency (UHF) measurements. The UHF technique utilises two methods to find the PD location, that is, the shortest path method and hyperbolic method. The shortest path method works based on the comparison of the measured data and the ones in the database. In the hyperbolic method, a hyperbolic equation is obtained between each two element subset of sensors. The coordinate that best fits all equations is known as the PD location, and can be obtained in three different ways, that is, iterative algorithms, the Fang method and Chan method. The convergence of iterative algorithms is limited by poor initial estimate, overshoot, mitigation of non-convergence etc. The Fang and Chan methods are two closed-form solutions that are used in the communication system to find the radiation source location. This article explains how to use these two methods to obtain the PD coordinate inside the power transformer. These two methods can find exactly the coordinate that best fits all hyperbolic equations. At the end of this article, several tests are carried out through CST software and the PD locations is estimated by all presented methods. The simulation results show how the Fang and Chan methods can overcome the limitations of the iterative method.