The Design Of RF Circuit For UHF Partial Discharge Sensor

Gas Insulated Switchgear(GIS) is widely used in high voltage system, the research about partial discharge(PD) of GIS is increasing. This paper introduces the present situation of the partial discharge test as well as their advantages and disadvantages. Based on the study of ultra-high frequency PD detection method, the problem about this detection method has been summarized. The pulse signal strength that is produced by partial discharge is weak. Space electromagnetic environment is complex and its interference on the discharge signal detection cannot be ignored. According to the different frequency band electromagnetic signal, band pass filter, high-pass filter and band-reject filter have been designed by ADS software to filter out interference signals. Base on space electromagnetic environment and the characteristics of partial discharge signals, the best working frequency of the low noise amplifier and detector is given. Base on the theoretical analysis, the matching network of low noise amplifier and detector are designed at the best working frequency. Finally, the RF circuits are tested. The test results show that the front-end RF circuit can effectively filter out space interference signal, and improve anti-interference ability of the sensor.The main work has done as follows :(1) This paper introduces the application background of GIS and the mechanism of partial discharge, as well as the main cause of the formation of partial discharge. It is focus on the analysis of the advantages and disadvantages of UHF partial discharge detection method and its future development.(2) The designing professional knowledge on RF circuits is introduced. The basic designing principle of filter is analyzed, which establish the theoretical basis for designing filter.(3) Base on the characteristics of partial discharge in high voltage substation and the electromagnetic environment, the best working frequency of UHF partial discharge detection sensor is determined in this paper. For effective detection of partial discharge signals and filtering space electromagnetic interference, different filters have been designed. The filters are designed and produced according to the results of the simulation of the ADS. The components and the functions of the RF circuit for partial discharge UHF sensor are introduced. Matching circuits of the low noise amplifier and detector are designed to realize the UHF partial discharge sensor in the best working state.(4) The matching circuits of RF module for the UHF partial discharge sensor are tested. The different filters are placed in the front-end of the UHF partial discharge sensor to measure the signals of partial discharge in GIS equipment. The test results show that filter can effectively filter out space electromagnetic.