Study On Development Of Partial Discharge In Typical Defects In Oil-Paper Insulation Aging Process

Transformer is the key equipment to protect the power system safe and stable operation,its internal insulation in the form of the main oil-paper insulation,its health is directly related to the operation of the entire grid security.Partial discharge is one of the main reasons for transformer insulation destruction,and it is also an important reference and expression form to characterize the degree of insulation failure.PD is used to study the development process of insulation discharge inside oil-paper insulation transformer,and the state of discharge severity has certain The practical significance.According to a large number of actual operation failure,it can be seen that the deterioration of insulation performance is the main reason leading to the failure of electrical equipment.Therefore,in this paper,the development and characteristics of partial discharge under the typical defects of oil-paper insulation with different aging degrees are studied.Accelerated thermal aging of the insulation board,to get the different aging degree of the board,used to simulate the insulation aging of the transformer in different years.The experiment platform of partial discharge under the typical defects of insulating paperboard was set up,and two kinds of surface discharge and needle plate discharge were built.The discharge capacity and the average discharge capacity of the paperboard from the partial discharge to the partial discharge breakdown are obtained.The parameters of the maximum discharge capacity,discharge frequency and average discharge capacity of the paperboard are obtained from the PD discharge data.The whole process is divided into three stages: the beginning of discharge,the development of discharge and the dangerous stage of discharge.Combined with the actual operation of transformer,the development law of partial discharge of oil-paper insulation under different aging degree is analyzed considering the influence of operating temperature.The development process of paperboard with different aging degree under four different temperature conditions was recorded,and the influence of temperature and aging on the development of partial discharge was analyzed.The results show that the effect of aging on the development of discharge is not significant at the initial stage.At the stage of discharge development and danger,the development rate of discharge increases with the increase of aging degree.The average discharge,discharge number and maximum discharge quantity At high temperature,the effect of aging on the development of partial discharge of oil-paper insulation is more significant,the greater the temperature,the greater the difference of the discharge characteristic parameters caused by different aging degree.