Partial Discharge Detection And Location Of Transformer Based On Electromagnetism Vector Sensor

In elecctric power system, the insulation hidden danger of transformer is always shownin the form of partial discharge, therefore, to find insulation degradation in time and toprevent accidents of the system, on line monitoring and locating of partial discharge is neededin nowadays. However, enormous electromagnetic interference in the practical circumstanceis a real puzzle of partial discharge monitoring, meanwhile, a detection method of higheraccuracy is not found yet, so that the detection and locating of transformer partial dischargecan not apply to the practical circumstance, which is out of the line of the detection demand ofmodern smart grid.UHF detection method, which is the research hot spot at present, owns its advantages inanti-interference and sensitivity in the existing detection method of transformer partialdischarge. However, internal structure of tranformer is complicated, factors as the transformercase and winding etc. will influence the propagation of UHF signal. Meanwhile, in thepractical circumstance, two or more discharge fault can be existed simultaneously and thenow used plane helical antenna sensor is scalar sensor, which can only detect that dischargehappenned or not, but can not used in quantitative analysis and discharging source locating ofpartial discharge.The electronmagnetism vector sensor is a 6-element polarity sensitive array, which canresponse 3 electric-field component and the corresponding 3 magnetic-field component of theincident electromagnetic signal simultaneously. The EMVS is extremely sensitive in thedirection angle and polarity information of incoming wave, therefore, it is fully used inelectromagnetic radiation detection and multi-signal source DOA estimation. Partial dischargeUHF signal is detected by EMVS in this article, and because of its direction and polaritycharaccter, EMVS is also used to distinguish false discharge signal source, therefore, the UHFmethod puzzle of quantitative analysis and locating can be solved by this sensor, and on thebasis of UHF detection, further study on transformer partial discharge pattern recognition canbe carried through. Thus, through theory and experiment lucubrate the following subject:propagation mechanism,frequency and polarity character as well as structure of UHFsignal;EMVS measurement model of partial discharge UHFsignal;discharge sourcedistinguish and locating based on spatial spectrum, etc. To solve the critical problem of howto use EMVS in transformer partial discharge detection in order to perfect UHF detection method can establish the foudation of discharge on line detection used in practicalcircumstance.