Design And Electromagnetic Properties Simulation Of Embedded Ultra High Frequency Sensor For The Online Monitoring Of Partial Discharge In Power Cable Accessories

With the rapid development of electric utility and improvement of the urban power network, power cable is widely applied in different voltage grade of distribution network because of its superior performance. Especially the power cable in high voltage and extra high voltage has occupied a very important position in the power network. But one of the main technical difficulties for the safety and stable operation of power cable network is the connecting technologies of high voltage cables. Statistics show that more than half of the high voltage cable failure is caused by the fault of the cable connection. Cable accessories have become a weak link and a typical position of the most high cable line insulation fault. Compared with the traditional test, the UHF (Ultra High Frequency) method can provide a choice of higher SNR for the measurement of partial discharge, and can effectively avoid interference signals. Because of its successful application in the GIS, domestic and overseas experts begin to try to extend the method to the measurement of partial discharge for cable accessories. The high frequency electromagnetic wave propagation generated by the partial discharge signals in cable accessories was simulated in the present paper, and the work can provides theoretical support for the design for UHF sensor.Using an electromagnetic wave simulation software Anoft HFSS, the high frequency electromagnetic model was established and the propagation characteristics of high frequencies wave were simulated and analyzed for a 110kV power cable linkage. The electromagnetic wave field excited by partial discharge signals under different frequency bands were investigated in the present paper, and the propagation characteristics of electromagnetic waves in the cable linkage are also studied.According to the analysis and simulation of the propagation of partial discharge electromagnetic waves, the requirements for UHF sensor design for the on-line monitoring of partial discharge of cable linkages are discussed and presented. According to the design requirements, the structure and geometry parameters of micro-strip antenna and helical antenna were investigated. Using the Ansoft HFSS software, the SWR(Standing Wave Ratio), antenna pattern and signal gain were calculated. The influence of structural parameters and dielectric constant were also investigated.