Research On Partial Discharge Of Transformer Internal Insulation System

Measuring insulation characteristic test methods such as winding insulation test,absorption ratio,polarization-ability factor,coil dielectric loss factor and capacitance,dielectric loss test and conventional test tube,can't find some of the potential insulation performance of transformer insulation fault,and AC voltage withstand test,lightning impulse and switching impulse high voltage withstand test will damage the internal insulation.According to statistics,in recent years,the high voltage,EHV,UHV power transformer insulation fault in 50%is due to the normal operation of the coil or the occurrence of inter section of the reasons for the discharge,transformer insulation deterioration of potential defects.According to the national standard,for the system voltage larger than 126kV power transformer,the PD test is a routine test,and the potential insulation faults can be found through the PD test.The measurement of partial discharge of transformer is an important method to judge the insulation condition of transformer,and it is also one of the important indexes to judge the insulation condition of transformer.Therefore,it is very important to detect the partial discharge in long time,which is caused by the long time induction withstand voltage and short time withstand voltage.Partial discharge measurement can be avoided as insulation test project failure properties,more and more large power transformer manufacturer and operation departments,and analyze whether there is high intensity region inside the transformer,because these areas may cause harm to the long-term safe operation of transformer.It is very important to solve the problem of partial discharge by means of partial discharge detection.However,due to the particularity of partial discharge detection and the complexity and variety of the discharge type,it is necessary for the system to master the partial discharge detection and problem analysis.In this paper,the principle of measuring the partial discharge by the pulse current method,the ultrasonic positioning method,the chromatography method and the high voltage dielectric loss method are analyzed.According to a large number of test data of typical test model,summarizes the characteristics of partial discharge waveform,summarizes the typical of common internal discharge measurement,and analyses the waveform characteristics of the test site of various kinds of interference.This paper also introduces the test method of the PD test,including the test wiring,equipment,test plan and process record.In addition,the method of PD analysis is presented,which includes the electrical positioning method and the ultrasonic positioning method.The use of electrical positioning method and ultrasonic positioning method,combined with the typical pattern,solve the Hongmiao Tai'an experimental station of 110kV transformer,220kV transformer,maintenance of sunshine state of Chu Wei River in Henan 110kV transformer and 1000kV UHV Transformer Partial Discharge problem.This paper gives a detailed description of the PD location and ultrasonic positioning of the transformer,and provides valuable experience for the partial discharge.