Impact of velocity on partial discharge characteristics of moving metal particles in transformer oil using UHF technique

Metal particles and bubbles are two typical impurities in transformer oil that can cause partial discharge (PD) and even electric breakdown. The PD characteristics are closely related to the motions of these impurities in flowing transformer oil. In this paper, the motions of impurities were obtained by a camera and a simulation model at first. Then, we employed three methods, namely, antennas, a non-inductive resistor, and the method recommended by IEC 60270, to measure the PD signals simultaneously. The breakdown experiments of transformer oil containing the metal particles and bubbles were also performed. In terms of these, single PD waveforms, statistical characteristics, and breakdown voltage were obtained. The results showed that the metal particles could excite ultrahigh frequency (300 MHz-3 GHz) PD signals, whereas bubbles only excited signals in the very high-frequency band (30-300 MHz). Moreover, the PDs induced by the metal particles had a higher repetition rate and a smaller amplitude than the PDs induced by bubbles. In addition, the metal particles easily caused PD, whereas bubbles easily led to the breakdown. Possible reasons for different discharge characteristics between the two impurities were discussed on the basis of the motions of impurities and the distortions of electric field.INDEX TERMS Metal particle, bubble, partial discharge, breakdown, flowing transformer oil.

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“…To perform PD and breakdown experiments, we established an experimental platform of flowing transformer oil [17], as shown in Fig. 1.…”

Section: Experimental Setup and Methods A Experimental Setupmentioning

confidence: 99%

“…Therefore, studies on flowing transformer oil are important for engineering applications. Our research team recently investigated the effect of oil velocity on PD activities induced by bubbles and metal particles [16], [17]. We found remarkable differences between PD activities in flowing and stationary states.…”

Section: Introductionmentioning

confidence: 98%

Comparison of PD and Breakdown Characteristics Induced by Metal Particles and Bubbles in Flowing Transformer Oil

et al. 2019

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“…However, it is frequently ignored, and the transformer oil is assumed to be stationary. In recent years, Tang et al [93,94] took the lead in proposing that the circulation of transformer oil due to various cooling systems could affect the migration of particles and subsequently alter the PD and breakdown characteristics of transformer oil. Then, comprehensive researches were executed, which involved observation and simulation of moving trajectory, PD and breakdown tests [95][96][97][98].…”

Section: Effect Of Fluid Flowmentioning

confidence: 99%

Review about PD and breakdown induced by conductive particles in an insulating liquid

et al. 2020

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In insulating liquid, a conductive particle becomes charged through the interaction with a conductor exposed to an applied field. Then, it migrates in the action of both electric field and fluid and causes the enhancement of local field when it is in proximity of the conductor with opposite polarity. The enhancement will lead to partial discharge (PD) and may even ignite full gap breakdown in special cases. This study reviews comprehensive researches relevant to these topics. In the first place, several theoretical methods about how to obtain the charges held by a conductive particle with known potential are introduced, so are experimental methods. Then, forces acting on the charged particle in liquid are classified, and its migration characteristics, as well as influential factors, are described. Subsequently, PD and breakdown mechanisms of liquid initiated by conductive particles are presented. The latter involves two cases: electric-field enhancement when the particle concentration is low and bridging phenomenon when it is high. At last, two important, but frequently ignored factors, i.e. dielectric barrier and oil flow, are highlighted, and the authors' suggestions for future work are put forward.

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“…The detection and localisation of PD using ultrahigh‐frequency (UHF) array technology for the early warning of power equipment has been extensively studied [4]. UHF technology has the advantages of high sensitivity and fast propagation speed [5]; however, limited by economic considerations, online UHF PD monitoring is only used for important devices such as gas‐insulated systems [6] and transformers [7]. Thus, a rapid PD detection and localisation method for air‐insulated substations (AISs) is proposed based on the UHF sensor array as a cost‐effective solution [8–10].…”

Section: Introductionmentioning

confidence: 99%

Partial discharge direction‐of‐arrival estimation in air‐insulated substation by UHF wireless array and RSSI maximum likelihood estimator

Han

Luo

Sheng

et al. 2020

IET Generation, Transmission & Distribution

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The quick detection and localization of partial discharge (PD) in an air-insulated substation (AIS) based on ultrahigh-frequency (UHF) sensor arrays are efficient for power equipment monitoring. The adopted UHF PD time difference of arrival (TDOA) methods mainly use the time difference of electromagnetic wave signals. Thus, the system requires both a high sampling rate and time synchronization accuracy, leading to a high cost and large size. In this study, the feasibility and accuracy of PD DOA in an AIS were investigated using a UHF wireless sensor array and the received signal strength indicator. First, the power pattern of the designed UHF wireless sensor array was obtained via an offline experiment. Then, a statistical approach to the PD DOA method based on the maximum likelihood estimator was employed to obtain the preliminary DOA result. Finally, interpolation and clustering algorithms were used to improve the accuracy of the DOA. A laboratory test was conducted. The average error of the PD DOA was less than 6°, and the cost-effectiveness and portability were clearly improved.

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Impact of velocity on partial discharge characteristics of moving metal particles in transformer oil using UHF technique

Cited by 26 publications

References 16 publications

Comparison of PD and Breakdown Characteristics Induced by Metal Particles and Bubbles in Flowing Transformer Oil

Comparison of PD and Breakdown Characteristics Induced by Metal Particles and Bubbles in Flowing Transformer Oil

Review about PD and breakdown induced by conductive particles in an insulating liquid

Partial discharge direction‐of‐arrival estimation in air‐insulated substation by UHF wireless array and RSSI maximum likelihood estimator

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