Experimental Study On Electrical Aging Characteristic Of 500kV Power Transformer Model Coils Turn-to-turn Insulation

500kV power transformer is one of the most important equipment in the power system, it play a role of power transmission. Whether it runs safe and reliable or not is very important to power system. While electrical aging of transformer turn-to-turn insulation is one of the main reasons which lead its damage. Study on electrical aging characteristic of 500 kV power transformer turn-to-turn insulation is of great significance on preventing the accident and enhancing the reliability of the equipment operation.The previous studies on electrical aging of power transformer did not consider about the complexity of the electric field distribution of power transformer turn-to-turn insulation, furthermore, the experimental mode did not think about the role of section field of power transformer coils. Therefore, material research is the emphasis of the previous studies but the consideration of the influence of the structure is insufficient. To solve the problems mentioned above, 500 kV power transformer turn-to-turn insulation model coils which used for experimental study on electrical aging characteristic are designed and made in this paper.In the study of the experiment, the method of accelerated life test is introduced,at the same time the method of step-voltage is selected as the experimental scheme of this topic, and ending the test by the experimental method of complete samples which can obtain the whole information of life. After the pretreatment of the model coils and the 25 th transformer oil, preliminary experiment is did in the first, and then concrete experimental scheme is formulated which is based on the data obtained in preliminary experiment, finally, formal experiment in room temperature an in 80?are did in order to obtain the experiment data. When analyze and process the data of experiment, the method of calculate the parameters is given in this paper which isbased on the thought of maximum likelihood method and the Nelson model. First of all, the formula of the model of inverse power is rewritten, and then the parameter N is calculated by using the interactive method when the parameter F(the square sum of the relative deviation of the parameter N in the formula of the model of inverse power which is rewritten) is the minimum, so the parameters N and A can be calculated. According to this method, the parameters N and A of the model of inverse power can be calculated by substituting into the data, in this way, the models of inverse power of 500 kV power transformer turn-to-turn insulation in room temperature and 80? are obtained. At last, the inverse power models between aging life and electric field strength in room temperature and operating temperature are obtained through the calculation and simulated analysis, which can be used to guide the actual transformer production design.