| Although Gas Insulated Switchgear (GIS) has the advantages of high reliability, longmaintenance cycle, and so on, there would be some insulation defects inside, theinsulation fault would be generated by its partial discharge (PD), thus affecting the safeand reliable operation, so the power equipment insulation condition detection is verymeaningful. To that end, the GIS partial discharge online monitoring technology iscarried out a lot of research at home and abroad. Study shows that the Ultra HighFrequency (UHF) is considered to be one of the most suitable for online detectingmethod due to the high frequency, wide band, and high sensitivity advantages. However,the signal of power calibration problems yet to be in-depth study, which is in fact nowfrontier subject urgently to be solved in line inspection. Based on the research status ofthis problem, the main achievements in this paper are as follows.(1) The rectangular plan spiral antenna sensor applicable for PD-site testing in GISis developed successfully through the deep research on the external sensing techniquesfor PD signal in GIS. Certain effective structures such as dielectric filled horn,wedge-shaped substrate and backing cavity are utilized during the antenna designprocess to miniaturize it while optimize standing-wave ratio characteristics. Theworking band of the antenna sensor reaches1.0~1.3GHz，1.8~2.7GHz，2.85~3GHz, andtesting gain of the antenna is11.7dB. In structure, metal materials shielded packagingon the back and part side of the antenna is designed to enhance the ability ofanti-jamming.(2) Four kinds of typical insulation defect models are constructed, and the fourkinds of typical insulation defect model of partial discharge source waveform areanalyzed. And according to the electromagnetic wave propagation theory and the finitedifference time domain method, on the basis of the existing local power waveform, theunimodal partial discharge pulse waveform and bimodal partial discharge pulsewaveform are put forward. The propagation characteristics are comparative analysisedto explore the difference in the propagation process of GIS between the different partialdischarge power waveform;(3) The metal protrusions defect model of GIS is used to calibrate the UHF signal,contrasted to four kinds of typical insulation defects in GIS model of discharge stability.The experimental system is constructed, and the characteristics of the signal by UHFmethod and pulse current method are extracted. the relationship between the parameters of the UHF signal and pulse current method signal has been analyzed with the samevoltage, different voltage, different spacing and different pressure.Through the above research, this paper developed a rectangular planar spiralantenna, and set up GIS partial discharge uhf detection system, the unimodal partialdischarge pulse power supply with the bimodal discharge detection of partial dischargepower supply situation has carried on the comparison and analysis, found that differentpartial discharge pulse power transmission of electromagnetic waves in GIS in theprocess of the typical differences, and through the defect in the metal protrusions on thecharacteristics of uhf signals with pulse current method characteristic has carried on thecontrast analysis. |
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