Electromagnetic Simulation Of Antenna For High- Frequency Measuring Corona Discharge Of Overhead Line

Corrosion of overhead lines occurs frequently.Generally,there is a high voltage between different wires on the overhead line.When the electric high-voltage electric field acts to overcome the air resistance,corona discharge occurs when the air is brightened when a small current is discharged.Corona discharge can cause many problems such as power loss,radio interference,and environmental pollution.At present,in order to reduce the corona discharge phenomenon,a method such as a voltage equalizing ring and a split wire is generally used.However,these methods can only reduce the corona discharge phenomenon and cannot completely avoid corona discharge.In order to ensure the safe operation of the power grid,it is necessary to monitor the overhead line corona discharge.At present,infrared thermal imaging and ultraviolet imager methods are widely used in corona discharge detection methods,but they all have defects.In order to improve the current monitoring method,this paper based on the principle of corona discharge generating pulsed electromagnetic field,explores a method of detecting discharge electromagnetic field with antenna,and realizes long-distance detection of overhead line corona discharge,which has certain application value.The main work of this paper is as follows:(1)The helical antenna and the logarithmic period antenna are selected for structural design,and both antennas require circular polarization.Therefore,in this paper,the theoretical design of the structural parameters of the two antennas is firstly carried out.In order to realize the circular polarization of the logarithmic periodic antenna,two pairs of logarithmic periodic antennas are used orthogonally.The final designed circularly-polarized logarithmic period antenna has a total length of about 1.1 m,a maximum length of 60 cm,and a total length of the spiral antenna of about 3 m and a diameter of 36 cm.(2)In order to verify the performance of the two antenna structures,the HFSS software is used to simulate the structure of the two antennas,analyze and adjust the antenna model,quantitatively analyze the antenna radiation pattern,input return loss,etc.,and finally get the best performance.The better antenna model(3)by comparing the simulation results of the two antenna models,it is verified that both models can detect signals in the specific frequency range of 200 MHz ~ 300 MHz.(4)For the sake of portability,this paper has produced a circular polarization logarithmic period antenna for corona discharge detection experiments.By performing experiments indoors,a significant pulsed corona discharge signal can be detected when a voltage of 26 kV is applied to a composite insulator with a withstand voltage of 10 kV.When the voltage is increased to 38 kV,the amplitude of the detected corona discharge signal increases.The VG transform of the corona discharge time domain waveform is used to obtain the spectrum.It is found that the frequency distribution of the corona discharge signal is in the range of 175 MHz to 300 MHz centered on 250 MHz.The monitoring effect of the antenna designed in this paper is confirmed by experiments.The circularly polarized logarithmic period antenna designed in this paper can effectively detect the corona discharge phenomenon of overhead lines.It has certain application value for ensuring the safe operation of the power grid and remote detection of corona discharge.