Experimental research on air-gap partial discharge properties in transformer oil-paper insulation

2013 ◽  
Author(s):  
Weigen Chen ◽  
Zhenze Long
Keyword(s):  
Experimental Research ◽  
Partial Discharge ◽  
Air Gap ◽  
Transformer Oil ◽  
Paper Insulation

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

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6995
Author(s):  
Bing Luo ◽  
Jian Wang ◽  
Dong Dai ◽  
Lei Jia ◽  
Licheng Li ◽  
...  
Keyword(s):  
Fluid Model ◽  
Partial Discharge ◽  
Opposite Polarity ◽  
Air Gap ◽  
Mechanism Analysis ◽  
Surface Charges ◽  
Practical Operation ◽  
Discharge Simulation ◽  
Dc Component ◽  
Paper Insulation

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.

Development of the Partial Discharge Inception Calculation Model in a Non-uniform Air Gap Considering the Effect of Humidity

2011 ◽  
Vol 131 (12) ◽  
pp. 1017-1023 ◽  
Author(s):  
Norihito Yanagita ◽  
Tatsuro Kato ◽  
Toshiaki Rokunohe ◽  
Takeshi Iwata ◽  
Hiroki Kojima ◽  
...  
Keyword(s):  
Partial Discharge ◽  
Calculation Model ◽  
Air Gap

scholarly journals Effects of Plasma Treated Alumina Nanoparticles on Breakdown Strength, Partial Discharge Resistance, and Thermophysical Properties of Mineral Oil-Based Nanofluids

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3610
Author(s):  
Norhafezaidi Mat Saman ◽  
Izzah Hazirah Zakaria ◽  
Mohd Hafizi Ahmad ◽  
Zulkurnain Abdul-Malek
Keyword(s):  
Thermal Conductivity ◽  
Plasma Treatment ◽  
Base Fluid ◽  
Breakdown Strength ◽  
Partial Discharge ◽  
Mineral Oil ◽  
Transformer Oil ◽  
Alumina Nanoparticles ◽  
Discharge Characteristics ◽  
Nano Alumina

Mineral oil has been chosen as an insulating liquid in power transformers due to its superior characteristics, such as being an effective insulation medium and a great cooling agent. Meanwhile, the performance of mineral oil as an insulation liquid can be further enhanced by dispersing nanoparticles into the mineral oil, and this composition is called nanofluids. However, the incorporation of nanoparticles into the mineral oil conventionally causes the nanoparticles to agglomerate and settle as sediment in the base fluid, thereby limiting the improvement of the insulation properties. In addition, limited studies have been reported for the transformer oil as a base fluid using Aluminum Oxide (Al2O3) as nanoparticles. Hence, this paper reported an experimental study to investigate the significant role of cold plasma treatment in modifying and treating the surface of nano-alumina to obtain a better interaction between the nano-alumina and the base fluid, consequently improving the insulation characteristics such as breakdown voltage, partial discharge characteristics, thermal conductivity, and viscosity of the nanofluids. The plasma treatment process was conducted on the surface of nano-alumina under atmospheric pressure plasma by using the dielectric barrier discharge concept. The breakdown strength and partial discharge characteristics of the nanofluids were measured according to IEC 60156 and IEC 60270 standards, respectively. In contrast, the viscosity and thermal conductivity of the nanofluids were determined using Brookfield DV-II + Pro Automated viscometer and Decagon KD2-Pro conductivity meter, respectively. The results indicate that the 0.1 wt% of plasma-treated alumina nanofluids has shown the most comprehensive improvements in electrical properties, dispersion stability, and thermal properties. Therefore, the plasma treatment has improved the nanoparticles dispersion and stability in nanofluids by providing stronger interactions between the mineral oil and the nanoparticles.

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