Research On Relationship Between Partial Discharge In Oil-paper Insulation And The Laws Of Electrical Trees’ Development

As essential apparatus in transmission lines, electrical power transformers’ operation condition has great influence on the safety of the whole power grid. If electrical deterioration occurs to oil-paper insulation, which is widely used for transformers’ insulation structure, it will do harm to transformers.Partial discharge,as the most common form of electrical deterioration, will genarate electriacnl tree that would shorten the insulation distance and thus reduce the reliability of transformers. So it’s critical to find out the relaitionship between the length of carbonized traces and partial discharge,and it’s also the main content of this paper.If we could acknowledge the information about development of carbonized traces by measuring and dealing with the partial discharge signal,it will be possible for us to establish relationship among partial discharge, carbonized traces and electrical deterioration of transformer insulation, which will help get us theoretical basis for the condition monitering of transformers.On the basis of previous research, we establish experiment platform,improve the test model,and rewrite the code for collecting and processing partial discharge signals from top to bottom, in order to investigate the relationship between partial discharge and development of carbonized traces. To get a fine result for the experiment,we test the circut board and the results show that the distributed potential system funtions well and is ready for the experiments.Soon afterwards,we conduct long-time and multiple tests for the oil-paper insulation pressborad under a constant voltage in order to get the pulse signal of partial discharge distributed potential signal and its phase signal.After dissection of oil-paper insulation pressboard and analysis of the signal, we find that the length of carbonized traces and the position of space charges has high degree of consistency.which indicates that where there is space charges,there is carbonized traces in the dissected pressboard. Besides, we could also find the clue of carbonized traces from the change of the distributed potential signal at power frequency which means that with the forward development of carbonized traces, the amplitudes of the multiple channels’ signals are almost the same where there are carbonized traces.