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Open AccessArticle

Feature Extraction and Comprehension of Partial Discharge Characteristics in Transformer Oil from Rated AC Frequency to Very Low Frequency

1
State Key Lab of Electrical Power System, Department of Electrical Engineering, Tsinghua University, Beijing 100084, China
2
School of Electrical Engineering, Xinjiang University, Urumqi 830047, China
3
State Grid Jibei Electric Economic Research Institute, Beijing 100045, China
4
North China Electric Power Research Institute Co., Ltd., Beijing 100045, China
*
Author to whom correspondence should be addressed.
Energies 2018, 11(7), 1702; https://doi.org/10.3390/en11071702
Received: 30 May 2018 / Revised: 23 June 2018 / Accepted: 26 June 2018 / Published: 1 July 2018
(This article belongs to the Section Electrical Power and Energy System)
The reactive current can be reduced effectively by decreasing the frequency of the voltage in partial discharge (PD) test, especially for equipment with large capacitance. Thus, the cost and volume of the test power supply can be economized. To figure out the difference of PD characteristics in transformer oil between rated alternating-current (AC) frequency (50 Hz) and low frequency, tests are conducted from rated AC frequency to very low frequency (0.1 Hz) based on impulse current method. The results show that with the decrease of frequency, the inception voltage increases. The maximum and mean magnitude of discharge and pulse repetition rate first increase slightly, then decrease obviously. The main features of the variation of phase resolved PD (PRPD) patterns, discharge statistical patterns (phase distribution of maximum and mean discharge magnitude, pulse repetition rate qmaxφ, qmeanφ, nφ; and number distribution of discharge magnitude nq), and their characteristic parameters (skewness Sk+, Sk; kurtosis Ku+, Ku; asymmetry Asy; and correlation coefficient Cc) are depicted in detail, which should be paid attention to when using low frequency voltage. The inner mechanism for these variations is discussed from the aspects of the influence on electric field distribution and discharge process of frequency. Additionally, the variation trend of PD characteristics with the decrease of frequency can provide more information about insulation defect, which can be the supplement for discharge mode recognition. View Full-Text
Keywords: partial discharge; low frequency voltage; PRPD; characteristic parameter; insulation defect diagnosis partial discharge; low frequency voltage; PRPD; characteristic parameter; insulation defect diagnosis
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MDPI and ACS Style

Zhou, Z.; Zhou, Y.; Huang, X.; Zhang, Y.; Wang, M.; Guo, S. Feature Extraction and Comprehension of Partial Discharge Characteristics in Transformer Oil from Rated AC Frequency to Very Low Frequency. Energies 2018, 11, 1702.

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