Author
Ali Mazhab Jafari
Bio: Ali Mazhab Jafari is an academic researcher from K.N.Toosi University of Technology. The author has contributed to research in topics: Partial discharge & Transformer. The author has an hindex of 1, co-authored 1 publications receiving 34 citations.
Topics: Partial discharge, Transformer
Papers
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TL;DR: In this paper, a multi-conductor transmission line model (MTLM) of transformer winding has been used to find partial discharge (PD) location in transformers, and two methods for calculation of model parameters were studied and the most suitable method was chosen based on comparison between measured and calculated transfer functions of a 132 kV/20 kV transformer.
37 citations
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TL;DR: In this paper, a new design of UHF antennas is introduced which is suitable to be used on the transformers in the HV laboratories of the manufacturers to ensure the applicability of the new antenna, experimental UHF PD measurements are carried out on a transformer tank model as well as on real power transformers.
Abstract: Partial discharge (PD) detection in the ultra-high frequency (UHF) range is state of the art. One of the most critical points in this detection method is adopting proper and suitable antenna design. In this paper, a new design of UHF antennas is introduced which is suitable to be used on the transformers in the HV laboratories of the manufacturers. To ensure the applicability of the new antenna, experimental UHF PD measurements are carried out on a transformer tank model as well as on the real power transformers. Installing several UHF antennas on the transformer tank to perform defect localization is also an important issue. There are rigorous limitations and lack of the places to install the antennas. This problem is almost solved by using the mentioned new antenna design. The proper positioning of the antennas is the other critical point in the UHF method. Placing the antennas in improper positions will damage the localization accuracy. In this paper, an automatic algorithm is introduced to determine the best installation positions for the antennas to enhance the localization accuracy. The efficacy of this algorithm is investigated by using the results of experimental measurements on power transformers.
88 citations
TL;DR: In this article, the authors proposed a method based on comparing the differences in the arrival times, to antennas in the transformer, of EM waves emitted from the PD source, and factoring in the influence of the transformer active part on the EM wave propagation.
Abstract: Nowadays, the localization of partial discharge (PD) in power transformers by measurement of ultra-high-frequency (UHF) electromagnetic (EM) waves from a PD source is receiving more attention. This method is based on comparing the differences in the arrival times, to antennas in the transformer, of EM waves emitted from the PD source. From the measured UHF signal, and factoring in the influence of the transformer active part on the EM wave propagation, the correct determination of an EM wave arrival time in the localization algorithm is a critical task that influences the accuracy of the UHF PD localization method. Nearly all weak points in the dielectric system of power transformers generate PD. These discharges gradually degrade the insulation, leading to transformer failure. It is possible to detect these defects in the early stages of PD generation by measuring and analyzing the PD data. Suitable maintenance and repair strategies can then be implemented.
63 citations
TL;DR: In this paper, a neuro-fuzzy technique that uses unsupervised pattern recognition was proposed to localize partial discharge (PD) source in power transformers, which showed a significant improvement in localizing PD for major types of PD compared to currently available techniques, such as orthogonal transforms and the calibration line method.
Abstract: Partial discharge (PD) is the most common sources of insulation failure in power transformers. The most important tools for quality assessment of power transformers are PD detection, measurement, and classification. As for the maintenance and repair of transformers, the major importance is the techniques for locating a PD source. The transfer function-based (TF) method for power transformers' winding in the high-frequency range is commonly used in power engineering applications, such as transient analysis, insulation coordination, and in transformer design. Although it is possible to localize PD in transformer winding using the transfer function (TF) method, this method cannot be used for transformers with no design data. Previous attempts toward finding a feature that localizes PD in transformers in general that lineate with PD location were found to be less successful. Therefore, in this paper, a neuro-fuzzy technique that uses unsupervised pattern recognition was proposed to localize PD source in power transformers. The proposed method was tested on a medium-voltage transformer winding in the laboratory. The results showed a significant improvement in localizing PD for major types of PD compared to currently available techniques, such as orthogonal transforms and the calibration line method.
48 citations
TL;DR: An optimum design of a Rogowski coil that can measure the PD signals from medium voltage cables, its accessories, and the distribution transformers is proposed that leads to the development of an integrated monitoring model for the components of a MV cable feeder.
43 citations
TL;DR: In this paper, the wavelet packets analysis was used as a tool for disk-to-disk partial discharge faults detection and localization in transformer windings, and a simulated model was developed for the transformer winding and the PD phenomenon mechanism.
37 citations