Experimental Research On The Relationship Between Partial Discharge And Dissolved Gases In Oil Of Oil-paper Insulation Transformer By Model

Transformer is the key equipment in the power system, so its long-termreliability is directly related to the safe operation of power grid. If we detectedthe latent fault in the transformer in time, we can investigate security risks asearly as possible and maintain the safe operation of power grid. The analysis ofgases dissolved in transformer oil is an important method to detect the internalfault of transformer. Currently, according to DL/T722-2000"Guide to theanalysis and the diagnosis of gases dissolved in transformer oil ", the analysis ofgases dissolved in transformer oil has been widely used as fault diagnosis andperiodic inspection in power grid. According to the improved three-ratio methodand the characteristic gas method in the Guidelines, we can can distinguishbetween overheated failure and discharging failure, and even can distinguishbetween low-energy discharge and high-energy discharge, but it can notaccurately determine the location and type of the fault, so when the equipmentwhich was diagnosed as a failed device returned the factory to disassemble,researchers always couldn’t find the starting point of failure and identify thecause of the failure further.In view of the above, this paper based on the analysis of gases dissolved inoil of abnormal cases designed Oil-gap discharge model, Oil-wedge dischargemodel, Surface discharge model, Induction discharge model, and furtherconducted simulation tests and analysis of dissolved gas in oil, on the basis ofdischarge faults may occur in practice. At last, author researched on thecharacteristic gas of different types of discharge fault, and made further researcheon the characteristic gas of the different distances under the same dischargemodel. Main contents are as follows: 1. Whatever long gap or short gap, when electrodes are bare metal, if iteither had a small radius of curvature of the electrode cross-section, thecharacteristic gas of spark discharge is consistent with basic features of C₂H₂, H₂as the main body in gases.2. When the radius of curvature of the bare metal electrode section largeenough, in the case of poor thermal performance of the medium between theelectrodes: When spark discharge occurs in long gap, the composition of thecharacteristic gas is mainly C₂H₂, H₂. When spark discharge occurs in short gap,the composition of the characteristic gas is mainly C₂H₂, H₂and C₂H4.3. Whatever long gap or short gap, when cover electrode with the insulatingpaper, if it either had a small radius of curvature of the electrode cross-section,the characteristic gas of spark discharge is consistent with basic features of C₂H₂,H₂as the main body in gases, and a small amount of CO, CO2.4. When cover electrode with the insulating paper, in the case of poorthermal performance of the medium between the electrodes: When sparkdischarge occurs in long gap, the composition of the characteristic gas is mainlyC₂H₂, H₂, and a small amount of CO, CO2. When spark discharge occurs in shortgap, the composition of the characteristic gas is mainly C₂H₂, H₂and C₂H4, and anumber of CO, CO2. And the rising speed of the components CO, CO2in shortgap is slightly higher than it in long gap.5. When the content of H₂and CH4exceeds the attention value, and thecontent of H₂is more than the content of CH4an order of magnitude, if only thecontent of C₂H₆was high in other hydrocarbon gases, we can almost certain thatthere is partial discharge in the interlayer of device.