Simulation On Ultrasonic-based Method To Detect Partial Discharge In Power Transformer

The major factor leading to the failure of the power transformer is insulation failure, while thevast majority of insulation failure is due to the impact of the partial discharge on the accumulationof insulating material. Therefore, the location detection for the power transformer partialdischarging is important for stable operation of the power system. Ultrasonic method for locatingpartial discharges has the advantage of positioning accuracy, immunity to electromagneticinterference, no equipment out of operation, etc. The research about the power transformer partialdischarge location based onthe ultrasonic method has academic and practical value.This paper systematically introduces the mechanism of partial discharge and the process ofpartial discharge producing ultrasonic, and carry out the experimental and simulation studies in thespread laws of the ultrasonic inside the power transformer. Experimental studies include:(1)At20℃, this paper measured respectively the ultrasonic propagation velocity in the transformer oiland oil-paper insulation;(2)This paper measured the influence of temperature on the ultrasonicpropagation velocity in transformer oil.(3)This paper measured the amplitude attenuation law dueto the absorption of ultrasonic transformer oil with the propagation distance increasing, and thereflection ofultrasonic by the oil-immersed insulation paper. In simulation studies, the sound sourcemodel ofpartialdischarge is built based on the ofprinciple ofpartialdischarge producing ultrasonic.Taking advantage ofthis sound source modeland the finite element modelofthe transformer, whenpartial discharge occurs inside the power transformer, the paper conducted respectively frequency-domain and time-domain finite element simulation finite element simulation with sound field. Theoutput points were arranged on the transformer wall to analog the ultrasonic array sensor.Simulation get the sound pressure spectrum in the frequency domain and sound pressure temporalpatterns of the array output points. According to the frequency domain and time domain spectrumfeatures, a small sound field database of the power transformer partial discharge is built. The soundpressure data measured by the ultrasonic array sensor is compared with that database, theoccurrence location ofpartialdischarge can be determined quickly.