Study On Discharge Development And The Gas Generation Law For Wedge Oil-Gap In Transformer Oil-Paper Insulation

Power transformer is one of the most important and expensive equipments inpower industry，and most of which is Oil immersed type transformer. The event ofpartial discharge can lead to aging and disruption of the insulation, and that mightthreaten its safety and reliability to operate the entire power network. Wedge-shaped oilgap discharge is the main form of transformer oil-paper insulation partial discharge,which developped and caused the sliding along the surface flash discharge easily. Thepaper studys development characteristics of partial discharge and law of the dissolvedgases in oil using step-up method and the constant pressure method that based onlaboratory partial discharge experiment platform and combined with a wedge-shaped oilgap discharge model. Specific studies are as follows:①In the experiment with booster method, maximum amplitude and frequency ofwedge oil-gap discharge are tend to increase with the rise of the voltage; H₂、CO、CH₄、C₂H₄、C₂H₆and C₂H₂are growing faster in the start stage, remain stable or declineslightly in the middle stage, increase suddenly in the end nearing breakdown. In theexperiment with constant pressure method, maximum amplitude and frequency presentu-shaped curve. They increase first, and then reduce, then increase at last; six kinds ofgas are growing faster in the start stage, remain stable in the middle stage, appear withincreasing trend in later stage.②They have correlation between the factors affecting the current state of thetransformer. The paper uses a association rule method to analysis the gas production inwedge-shaped oil gap model and the discharge energy of different intervals, andconcludes that the generation of Hydrogen（H₂） needs lower energy, but the dischargefrequency plays a dominant role in generating H₂. The carbon monoxide （CO）formation condition is similar to carbon dioxide （CO2）, the two gases are easy to beobtain at the same time, furthermore high energy discharge is easier to produce CO andCO₂. The energy that caused the discharge of methane （CH₄） and ethylene （C₂H₄） isn’thigh. Due to a large discharge frequency, the discharge of low energy range has agreater impact on the generation of CH₄and C₂H₄than the discharge of high energy.The generation of acetylene （C₂H₂） needs higher energy, and the cracking is moredifficult. With the improvement of the discharge energy, the generated gas compositionis more complex, and gas total amount is more. Compared with the IEC three-ratio method, association rule results are more clear, which do not appear code missing, andnot lead miscarriage of justice in the fuzzy boundary.③By major-content method, six major factors were selected from the above29statistic operators of H_qmax（φ）、H_qave（φ）、H_n（φ）、H_n（q）, and the six major factors areindependent with each other; Results show that there is correlation between six kinds ofgas and six major factors by correlation and regression method; multivariable linearregression model of six kinds of gas and six major factors was presented. Among the sixkinds of gas, there is a more significant relationship between six major factors andincremental gas of H₂, CO, CH₄and C₂H₆.