Tests And Researches Of Partial Discharge In Interturn Insulation Of 500kV Power Transformer Coil Models

Large power transformer is the core in the power system, and its safe and stable operation is important for the entire power grid. Insulation failure is an important factor that affects the safe and stable operation of the power transformer, and the turn to turn insulation fault is the main factor. For the transformer winding, slight inter turn discharge may cause inter turn short circuit or even more serious consequences.Therefore, it is significant to study the development of partial discharge in transformer windings.Transformer interturn insulation partial discharge test platform was constructed in this paper, reference 500 kV power transformer coil insulation process, designed and fabricated interturn insulation partial discharge test model coil, step-stress tests were applied to coil models, the partial discharge signal is collected by pulse current method in the experiment, interturn partial discharge basic characteristics,two-dimensional phase distribution were studied at room temperature and 80?.From the results, under the step voltage, maximum amplitude and average amplitude of pulse, pulse power increased with increasing voltage; pulse repetition rate showed the local maximum; in initial partial discharge voltage, the discharge pulse signal distribution of Hqmax(?),Hqn(?) and Hn(?) showed apparent phase area;the phase width distribution of two dimensional spectrum is basically the same in the test environment of the room temperature and 80?; change of test temperature did not change trend of the pulse amplitude and pulse average amplitude, but it has a great influence on growth mode of the pulse amplitude and pulse average amplitude,the test environment of high temperature significantly reduces the maximum value of the pulse repetition rate in the process of test record.