| Generally, partial discharges deteriorate the insulation materials in transformers due to chemical processes caused by their high energy electrons or accelerated ions during the operation of transformers. Ultimately, they may cause electrical breakdowns in transformers. These partial discharges produce both electrical and acoustic signals.In transformers, these electrical or acoustical signals are used to indicate the presence of partial discharges and additionally, are used to attempt to pinpoint the discharge origin. Since 1960 many methods have been explored to locate partial discharges within windings. Unfortunately, to date, no general and reliable location method is available for both manufacturers and utilities.The objective of this research was to develop an electrical method for locating partial discharges within windings.This research has developed a general method for locating partial discharges within windings by means of electrical terminal measurements. The method uses a detailed electrical model of the winding in conjunction with developing an analytic tool to establish the location of the partial discharge within the winding. All possible partial discharge locations in the winding model are explored by calculating the winding responses using the UNITRAN program. The analytic tool is developed by applying the Prony function transformation to the volt-time terminal response caused by the partial discharge, cross-correlation functions, correlation coefficients, fitting-error formulas, and finally the location identifier.Three helical coils are presented to simulate the general applicability of this method, and then this method is applied to a disk coil. The results indicate that this method is general, robust, intelligent, fast, and economic. |
