| GIS equipment is widely used in power system because of its advantages of good sealing,strong anti-interference ability and low failure rate.However,once faults happen on GIS equipment,the process of location and overhaul is more difficult than that of conventional electrical equipment.Therefore,the timely warning of GIS equipment insulation failure is very important.Ultra-High Frequency partial discharge detection technology with strong anti-interference ability has become an important means of condition monitoring and fault diagnosis of GIS equipment,but the antenna with large gain and bandwidth is usually large in size,which is not convenient to be applied to partial discharge field live detection and built-in online monitoring of GIS equipment with complex structure.In this paper,a new type of miniaturized plane spiral antenna loaded with composite function with amplitude increasing linearly is designed.The miniaturized parameters of the antenna are simulated and optimized by Ansoft HFSS electromagnetic simulation software,and the performance of the miniaturized antenna is verified by the simulated defect partial discharge test.The main contents of the paper are as follows:(1)In the simulation software,the radiation unit model of the traditional Archimedes plane spiral antenna is built.The influence of the helix width W on the antenna performance is discussed by comparing the Voltage Standing Wave Ratio curve and the input impedance curve of the antenna.The simulation results show that the increase of the helix width W will lead to the deterioration of the low frequency characteristics of the antenna,but the input impedance characteristics of different helix width W are basically the same in the frequency band.At the same time,when W is 2mm,the floating degree of the parameters such as the standing wave ratio and the input impedance is the smallest,and the virtual part of the impedance is also the closest to zero.(2)Based on the traditional Archimedes plane spiral antenna with the width of 1mm designed above,the influence of the miniaturized parameters of the radiation unit: the proportional coefficient K and the number of sinusoidal periods n on the performance of the antenna is discussed by modeling and simulation in the software.The simulation results show that the low-frequency characteristics of the miniaturized spiral antenna deteriorate with the increase of the proportional coefficient K or the number of sinusoidal periods n,and the floating amplitude of the real part and the virtual part of the antenna impedance is increasing.(3)The model of plane helical antenna with miniaturization parameter: k is 0.03 mm and N is 40 is established and its performance is simulated.The results show that in the working bandwidth of 700 MHz to 3000 MHz,the miniaturized antenna can meet the engineering design requirements of Voltage Standing Wave Ratio less than 2,and the directional characteristics and gain size of the antenna in the bandwidth can meet the needs of ultra-high frequency partial discharge detection.(4)A partial discharge test is designed to simulate the typical defects of GIS.The detection performance of miniaturized antenna is verified by comparing the peak value and Signal to Noise Ratio of the discharge signal to other two antennas with larger gain.The experimental results show that when the partial discharge drive voltage is the same,the larger gain of the antenna is,the larger amplitude of the detected partial discharge waveform is.However,because the background noise level of the antenna with larger gain is higher,the Signal to Noise Ratio level of the three antennas is similar,which shows that the detection performance of the miniaturized antenna is good. |
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