Partial Discharge Simulation of Air Gap Defects in Oil-Paper Insulation Paperboard of Converter Transformer under Different Ratios of AC–DC Combined Voltage

Bing Luo, Jian Wang, Dong Dai, Lei Jia, Licheng Li and Tingting Wang
Additional contact information
Bing Luo: China Southern Power Grid Research Institute Co., LTD, Guangzhou 510663, China
Jian Wang: School of Electric Power, South China University of Technology, Guangzhou 510641, China
Dong Dai: School of Electric Power, South China University of Technology, Guangzhou 510641, China
Lei Jia: School of Electric Power, South China University of Technology, Guangzhou 510641, China
Licheng Li: School of Electric Power, South China University of Technology, Guangzhou 510641, China
Tingting Wang: China Southern Power Grid Research Institute Co., LTD, Guangzhou 510663, China

Energies, 2021, vol. 14, issue 21, 1-13

Abstract: A converter transformer is important primary equipment in a DC transmission project. The voltage on the valve side winding is complex when the equipment is running, including DC, AC, and AC–DC combined voltage. The insulation structure of the valve side winding of a converter transformer is an oil-paper insulation structure, which may have a variety of defects in the manufacturing stage and daily use, resulting in partial discharge. Therefore, it is the key to studying the partial discharge characteristics and mechanism of oil-paper insulation under AC–DC combined voltage. In this paper, we build a two-dimensional air gap model of oil-paper-insulated pressboard considering the actual particles and actual reaction based on the fluid model. The characteristics and evolution mechanism of partial discharge (PD) in pressboard under different AC/DC combined voltages are studied by numerical simulation. The results show that when the DC component increases, the polarity effect of partial discharge is more obvious, while the potential and discharge intensity in the air gap decrease. Further analysis revealed that the DC component in the combined voltage accumulated a large number of surface charges on the surface of the air gap, and the space charge distribution was more uniform and dispersed, which generated an electric field with opposite polarity to the DC component in the air gap and, then, inhibited the development of local discharge in the paperboard. The results of the simulation are consistent with the previous experimental phenomena, and the mechanism analysis of the simulation results also verifies the previous analysis on the mechanism of experimental phenomena. This will lay a theoretical foundation for the further study of partial discharge phenomenon of oil-paper insulation structures in practical operation in the future.

Keywords: partial discharge; combined voltage; space charge; surface charge density (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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