Study On UHF Partial Discharge Based On Planar Spiral Antennas And LabVIEW Platform

Partial discharge(PD) is one of the most important factors causing electricalequipment insulation faults. It is effective to judge the insulation condition ofelectrical equipments and provide early warnings to insulation faults through PDdetection, which has great value to insure stable performance of electricalequipments.There are many methods for PD detection, one UHF(Ultra-HighFrequency) PD detection has gained more and more attentions for its advantages,such as having broad bandwidth, high sensitivity, and superior anti-interferenceperformance and so on.In this paper, based on the PD mechanism, two kinds of UHF sensor calledplanar spiral antenna are designed using an electromagnetic wave simulationsoftware Ansoft HFSS, which have a wide band from0.3to3GHz and a goodstanding wave ratio(SWR) less than2.0. Single-channel and double-channel testprograms are developed based on the LabVIEW platform, with the functions ofdigital filter, threshold analysis, envelope acquisition, time domain analysis,frequency domain analysis, data storage and so on. In addition, the test dataanalysis program is written to deal with the test data and summarize theexperimental results, which can effectively extract many parameters andwaveform graphs. In the lab, the test platform is established for study on thecorona discharge, the pattern recognition of five types of discharge models andthe attenuation characteristic of UHF signals.By the test, the waveform graphs and the signal characteristics of UHFsignals causing by the corona discharge are acquired. On the basis of waveformsof the five types of discharge models, the energy distribution spectrum throughmathematical transformation is induced, and it is proved that two parameters of the energy distribution spectrum can be the characteristic parameters to recognizepatterns of the five discharge models. The same UHF signals are detected atdifferent distance, and by comparing five parameters of the UHF signals, we gaintheir attenuation characteristic curves varying with the radiation distance.