Research And Design Of Power Transformer Partial Discharge Detection Technology

Power transformer is one of the most important power equipment in the operation ofthe power grid, with people’s improving requirements in work and in live, we need to meethigh-level requirements in the stability of power grid operations, so for most manufacturersand power departments, it concerns a lot if the operation of the power transformer can bereliable and safety. Of all the problems, insulation degradation is one of the commonbreakdowns of power transformer, however, the cause of insulation degradation evenbreaking down mostly due to partial discharge in power transformer insulation structurephenomenon. Therefore, the power transformer partial discharge detection has importantsignificance to the transformer running state inspection and its breakdown maintenance.Partial discharge measurement is a measure that detects the reliability of the internalinsulation structure in the power equipment, it’s an important indicator, so the test aims atproving that whether the electrical equipment has destructive power for the internalinsulation structure.At the moment, the pulse electric current measurement method is easy toquantitatively measure and rich in measurement information, so that it becomes widelyused in power transformer partial discharge detection system, and becomes the traditionaland main test method. But using the pulse electric current measurement method, there aremany problems. One is the signal noise suppression when collecting, the other iscalculating power positioning algorithm. This paper expounds the importance oftransformer partial discharge test, principle, standard of measurement and test method,using the method of pulse current method to design detection circuit above such problems,and conducted tests and research as the following:(1) This paper analysis a variety of partial discharge detection technology at home andabroad, then expound the principle, advantages and disadvantages of various measuringmethods. Pulse current method is used to design the power transformer partial dischargedetection system of the basic measuring circuit.(2) Analysis interference noise types when processing partial discharge measurement,and put forward a variety of noise interference suppression method，And put forward thecombination of Fourier transform discrete binary wavelet transform method of digitalfilter. (3) Analysis various physical and chemical phenomena in Partial discharge, researchon various power source locating method. Analysis the principle of locating the partialdischarges in power transformer using ultrasonic wave, analysis its propagation velocity,attenuation and propagation path in various physical and chemical medium. Summarized avariety of combining ultrasonic power orientation method, and the ultrasonic locating ofthe acoustic positioning method, puts forward the least squares method to calculatedetermines the location of the set power.(4) After the research and design of the partial discharge measurement system’smeasuring circuits, interference suppression, and positioning, we carried on the simpleanalysis and the basic measuring circuit design for transformer partial discharge on-linemonitoring.(5) Through the analyze of a110kV substation transformer data which is out ofoperation for repair due to partial discharge, we demonstrates the feasibility of transformerpartial discharge measurement system.