Partial Discharge Localization Using Electromagnetic Time Reversal: A Performance Analysis

Abstract

In this study, first, a comparison on the application of electromagnetic time reversal (EMTR) and time difference of arrival (TDoA) in partial discharge localization in power transformers is presented. A two-dimensional finite-difference time-domain simulation is used to calculate the signal recorded by the sensors. Results show that, in a transformer tank excluding its windings, both methods yield similar results in terms of location accuracy, although the EMTR method only needs one sensor to localize the partial discharge (PD) source while the TDoA method needs at least three sensors in the 2D localization problem. However, the presence of transformer windings leads to a degradation of the performance of the TDoA method if the line of sight from the source to the sensor is blocked by any of the winding blocks. On the other hand, the presence of the transformer windings has an effect on the localization of PD sources that occur between two adjacent phase windings when the distance between the outer winding distances is shorter than the minimum wavelength, λ min. The degradation is directly caused by the diffraction limit. It is shown that, if the distance between two adjacent phase windings is greater than λ min , the EMTR process can locate PD sources occurring between two adjacent phase windings with acceptable accuracy. A case of occurrence of PDs in close proximity (less than λ min /2) to a single metallic object is analyzed both numerically and experimentally. The analysis reveals that although a degradation in the accuracy of the localization is observed compared to the case of longer distances between the PD source and the metallic object, a reasonable localization error of 10 mm (corresponding to λ min /10) is obtained. INDEX TERMS Experimental analysis, partial discharge localization, time difference of arrival, electromagnetic time reversal process, transformer tank.

An experimental validation of partial discharge localization using electromagnetic time reversal

“…It should be noted that the locations closer than λ min /2 to the transformer winding and tank were removed from the set. As discussed in 19 , PDs closer than about λ min /2 to the transformer tank or windings are not accurately localized using the proposed method. Second, the proposed method is applied to localize each PD source.…”

“…S2 , one of the PD locations (in the bottom right corner) has not been accurately located. The reason behind this large error is its vicinity to the tank wall (exactly λ min /2) (see 19 for more discussion).

Figure 3 The estimated location versus the actual location of PD sources for the 2D transformer model shown in Fig.

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“…However, the geometry of the tank and in particular the presence of the transformer windings has an effect on the localization of PD sources that occur either between two adjacent phase windings when the distance between the outer winding distances is shorter than the minimum wavelength. Furthermore, a degradation in the accuracy of the localization is observed when the PD is located in the immediate vicinity of a metallic plane or object (within λ min /2) 19 .…”

“…Moreover, the presence of the transformer tank acts as a cavity 29 , emulating an infinite number of sensors in the TR method, therefore increasing its performance. In particular, the EMTR method does not require line-of-sight between the PD source and the sensor, as opposed to TDOA-based approaches 19,28 . Figure 11.…”

Non-Contact Methods for High-Voltage Insulation Equipment Diagnosis during Operation

“…Therefore, it is necessary to control the occurrence of local overvoltage during the high-voltage insulation operation. It will be more convenient to carry out overvoltage remotely and contactless because in this case there is no need to decommission the equipment [20][21][22][23][24][25][26]. Yet, despite the existing urgency, the degree of development of such control methods has been low until now.…”