On the Feasibility of Gap Detection of Power Transformer Partial Discharge UHF Signals: Gap Propagation Characteristics of Electromagnetic Waves

Zhang, Xiaoxing; Zhang, Guozhi; Li, Yalong; Zhang, Jian; Huang, Rui

doi:10.3390/en10101531

Cited by 15 publications

(12 citation statements)

References 12 publications

(20 reference statements)

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“…Several PD detection methods have been developed according to the physical properties of the insulation system, which accompany PD activity, such as current pulse method [21], ultrasonic detection, ultra-high-frequency (UHF) detection, and the optical method [22,23]. However, the lower frequency limit of conventional pulse current methods is close to that in the high-frequency transformer, the ultrasonic detection is not sensitive enough because of the complex acoustic impedance, the UHF signals are affected by communication signals, and there is still no known experience with optical measurements in this kind of electrical equipment.…”

Section: Partial Discharge Measurement Setupmentioning

confidence: 99%

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Partial Discharge Analysis in High-Frequency Transformer Based on High-Frequency Current Transducer

et al. 2018

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High-frequency transformers are the core components of power electronic transformers (PET), whose insulation is deeply threatened by high voltage (HV) and high frequency (HF). The partial discharge (PD) test is an effective method to assess an electrical insulation system. A PD measurement platform applying different frequencies was set up in this manuscript. PD signals were acquired with a high-frequency current transducer (HFCT). For improving the signal-to-noise (SNR) ratio of PD pulses, empirical mode decomposition (EMD) was used to increase the SNR by 4 dB. PD characteristic parameters such as partial discharge inception voltage (PDIV) and PD phase, number, and magnitude were all analyzed as frequency dependent. High frequency led to high PDIV and a smaller discharge phase region. PD number and magnitude were first up and then down as the frequency increased. As a result, a suitable frequency for evaluating the insulation of high-frequency transformers is proposed at 8 kHz according to this work.

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Section: Partial Discharge Measurement Setupmentioning

confidence: 99%

“…where N q is the number of space charge; ∆t is the discharge interval of PD (s); τ d is the time between the occurrence of the power voltage amplitude larger than PDIV and the first discharge [22]:…”

Section: Frequency-dependant Pd Number and Magnitudementioning

confidence: 99%

Partial Discharge Analysis in High-Frequency Transformer Based on High-Frequency Current Transducer

et al. 2018

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“…PDs produce electromagnetic waves in the range of 300 MHz up to 3 GHz [8], [9]. As a result, electromagnetic source detection methods are applied to locate PDs in the ultra-high-frequency (UHF) band.…”

Section: Introductionmentioning

confidence: 99%

Partial Discharge Localization Using Electromagnetic Time Reversal: A Performance Analysis

et al. 2020

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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.

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“…According to the installation location of the UHF antenna sensor, the UHF method can be divided into three categories: built‐in method, dielectric window method, and external method , as shown in Fig. .…”

Section: Introductionmentioning

confidence: 99%

“…In view of the advantages of the external UHF method, Refs verified its feasibility of PD detection for transformers with an external UHF antenna sensor. Refs have analyzed the propagation characteristics of EM wave signals in transformer gaps. Ref designed an external Vivaldi antenna sensor used to obtain the EM wave signal leaked from a nonmetallic insulation gap and verified its sensitivity through experiments.…”

Section: Introductionmentioning

confidence: 99%

Ladder‐Wise calculation method for z‐coordinate of transformer PD source based on planar layout UHF antenna sensors

Zhang

Cheng

et al. 2019

IEEJ Transactions Elec Engng

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In locating a transformer partial discharge (PD) source, there is a large fluctuation error in the z -coordinate of the location, which results with planar layout ultrahigh-frequency (UHF) antenna sensors. For the large fluctuation error, this paper first theoretically analyzes the reason. According to the theoretical analysis results, a ladder-wise calculation method of the PD source z -coordinate is proposed: first, the x -and y-coordinates of the PD source are calculated, then the univariate equation f (z ) is derived, and the z -coordinate of the PD source is obtained by f (z ). Finally, the positioning effect of the ladder-wise calculation method for PD source z -coordinate is verified experimentally. Experimental results show that the proposed method can reduce the fluctuation of the z -coordinate of the PD source from 0.6 to 0.2, and when the PD location sample set is ≥10, the average absolute error of the z -coordinate is reduced from about 0.4 m to less than 0.1 m.

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On the Feasibility of Gap Detection of Power Transformer Partial Discharge UHF Signals: Gap Propagation Characteristics of Electromagnetic Waves

Cited by 15 publications

References 12 publications

Partial Discharge Analysis in High-Frequency Transformer Based on High-Frequency Current Transducer

Partial Discharge Analysis in High-Frequency Transformer Based on High-Frequency Current Transducer

Partial Discharge Localization Using Electromagnetic Time Reversal: A Performance Analysis

Ladder‐Wise calculation method for z‐coordinate of transformer PD source based on planar layout UHF antenna sensors

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