562 / 2022-03-30 09:36:36

Research on Dissolved Gas Characteristics in oil of Power Transformer On-load Tap-changer

dissolved gases in oil,disruptive discharge,topsis

     At present, in the fault diagnosis method of on-load tap-changer, it is unreasonable to directly characterize the on-load tap-changer as normal or fault, ignoring that the occurrence of a fault is a gradual process. In this paper, three electrodes are designed to simulate the development process of the on-load tap-changer fault discharge. Based on the chromatographic data of oil sample detection, the fault degree of the on-load tap switch between fault and normal is quantified， classification of fault degree. Thus more specific understanding of the fault situation, reduce economic losses. Firstly, an experimental platform is built to simulate the insulation defect model of the on-load tap changer, and the electrode structures of tip discharge, suspension discharge, and surface discharge are established. Three kinds of electrodes respectively in three kinds of gap 1mm, 3mm, 5mm discharge breakdown experiments occurred five times; Secondly, 40 mL of oil samples after breakdown were collected by glass needle, and the types and contents of characteristic gases in oil were detected by gas chromatography; Finally, using the TOPSIS method, set the fault state of the on-load tap-changer as the negative ideal solution, set the normal state of the transformer as the positive ideal solution, and calculate the closeness to the negative ideal solution. Taking the oil chromatographic data under fault conditions as the reference sequence, the grey correlation degree is calculated. The weighted sum of the two results is used as the quantitative value of the fault state. Through the experiment: the quantified value of the fault state is between [0, 0.5], indicating that the transformer state is close to the normal state at this time, and the transformer is in a relatively healthy state in this state; The quantified value of the fault state is between (0.5, 0.9], the transformer state is close to the fault state. The higher the value, the deeper the fault degree of the transformer; The quantified value of the fault state is between (0.9, 1], the possibility of failure is extremely high, and it should be stopped immediately for maintenance. The method can diagnose the fault of the on-load tap changer systematically, it can infer the transformer on-load tap-switch fault specific degree, it can reduce the equipment failure rate.