201. Partial Discharge of Needle-Plane Defect in Oil-Paper Insulation under AC and DC Combined Voltages: Developing Processes and Characteristics
- Author
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Shengchang Ji, Jiantao Sun, Lingyu Zhu, Xining Li, and Yanjie Cui
- Subjects
Forward converter ,converter transformer ,Control and Optimization ,Materials science ,partial discharge (PD) ,020209 energy ,Energy Engineering and Power Technology ,02 engineering and technology ,lcsh:Technology ,01 natural sciences ,law.invention ,law ,Electric field ,oil-paper insulation ,needle-plane defect ,AC/DC proportion ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Electrical and Electronic Engineering ,Transformer ,Engineering (miscellaneous) ,010302 applied physics ,Pressboard ,lcsh:T ,Renewable Energy, Sustainability and the Environment ,business.industry ,Electrical engineering ,Amplitude ,Partial discharge ,Optoelectronics ,business ,Energy (miscellaneous) ,DC bias ,Voltage - Abstract
Partial discharge (PD) behaviors of oil-paper insulation is distinctive in AC and DC combined electric fields in converter transformers from PD behaviors in pure AC or DC electric fields. The present study focuses on the PD developing processes and characteristics of oil-paper insulation systems with needle-plane defects under different AC/DC proportions. The degradation of oil-paper insulation can be accelerated by PD pulses incurred by needle-plane defects. AC-DC combined voltages are applied to the needle-plane defect model simultaneously in the established experimental platform, and the proportions of AC/DC voltages are decided according to the cases in actual converter transformers. The developing processes from the initiation of partial discharge until final breakdown were observed for each AC/DC proportion. PD parameters and patterns were acquired by a detector using the pulse current method. The test results indicate that the inception and breakdown voltages increase with the increase of the DC component in AC-DC combined voltages. However, pulse repetition rate and amplitude of PD shows a descending trend when AC/DC proportion decreases. Meanwhile, the PD recurrence rate in the phase between 180° and 360° becomes higher than that in the phase between 0° and 180° at the initial stage as the DC proportion increases; high-amplitude discharges mainly occur in the phase range between 180° and 360° when the pressboard is close to breakdown. The current study is useful in further research on fault diagnosis in converter transformers.
- Published
- 2017