| National UHVDC transmission projects show a rapid development trend.At the same time,our state has vigorously developed the independent research and design of the UHV converter transformer,and the insulation design is a very important part of it.At present,the design is mainly based on foreign companies,so comprehensive and accurate insulation material performance parameters are urgently needed to provide a basis for the insulation design made in China.The oil paper insulation structure is the main insulation in the converter transformer,and the partial discharge characteristics and surface flashover characteristics of the processed parts of the electrical paperboard machine can reflect the insulation performance,which are the key parameters needed in the insulation design.At present,the main research is carried out on insulating paperboard.There is not a lot of research on the forming parts processed by electrical insulation board,such as insulation braces,insulation blocks,and insulation bolt,there is a lack of reliable reference in insulation design.Moreover,the current research does not consider the inaccurate test results caused by changes in the moisture content of samples in the test process.Therefore,this paper developed a set of simulation of the converter transformer actual operation integration of closed discharge test inspection device,at the same time,in view of the high density electrical board machined parts in poisoned the characteristics and flashover characteristics of actual research,enrich the basic database,the quality evaluation method was developed based on the discharge characteristics at the same time,to provide a basis for the selection,optimization of insulation design.The main contents are as follows:(1)A set of integrated oil-paper insulation material pretreatment and electrical characteristics measurement test equipment was developed.The pretreatment process of insulation material and the discharge characteristics measurement process were serialized,and the problem of water inhalation in the process of the sample being tested and the air contact was solved.At the same time,the actual operation condition of the transformer could be simulated,and the measurement accuracy was improved.(2)It is concluded that B has the best insulation performance and the least dispersion under different components,A is the next,and C is the worst.The initial field intensity decreases with the increase of electrode spacing.The initial discharge quantity of local discharge ranges from 7.03 to 13.23pc.The local discharge extinguishing field intensity is slightly lower than or equal to the initial field intensity,and the decreasing degree is distributed in the range of 3.2%～9.6%.The discharge characteristics of machined parts are distributed in different fields with different electrode spacing.(3)It is concluded that the flashover field intensity of B was the largest among all machined parts,followed by A and C.The flashover field intensity of A and B ranges from 2.27 to 2.45kV/mm,5.8%to 12.7%lower than that of pure oil gap,and C ranges from 2.08 to 2.19kV/mm,15.8 to 20%lower than that of pure oil gap.In terms of surface morphology,B is the most reasonable embossed arrangement.The number of embossed grooves is more intensive and the size is larger,which can better hinder the development of surface discharge.(4)A quality evaluation method for machining parts of high-density electrical paperboard was proposed based on entropy weight method,and the quality evaluation results of various manufacturers were obtained based on the measured data of machining parts’ discharge characteristics.The rationality of this method was verified by taking insulation strings as an example.The final evaluation results of various manufacturers were ranked as follows. |
PDF Full Text Request