Research On Detection Technology Of Power Grid Equipment Insulation Materials Based On Terahertz Technology

With the continuous improvement of the scale of my country’s power grid and the explosive growth of power demand,the requirements for the reliability and stability of power equipment are getting higher and higher.In order to ensure the safe operation of power grid equipment,it is necessary to carry out regular inspection and maintenance of insulating devices of power equipment.Insulation generally exists in three ways: gas,liquid and solid insulation.In the process of production,installation and operation and maintenance,insulating materials are often affected by factors such as electricity,heat,environment and their combined effects,which will cause defects or damages to different degrees.The insulation damage of the insulation device will occur,and the insulation performance will also be greatly reduced,which will cause great hidden dangers to the safe and stable operation of the electrical equipment.Therefore,it is particularly important to discover the insulation defects existing in the operation of power equipment in time,and to judge the insulation operation status of the equipment.Terahertz time-domain spectroscopy is a novel and high-precision detection technology that has been widely used in many fields.When THz waves interact with materials,the THz spectra of these substances contain spectral information that can identify them.This paper uses terahertz time-domain spectroscopy to perform terahertz spectroscopy analysis on sulfur hexafluoride gas,transformer oil and composite insulators commonly found in power grid equipment,and completes the analysis and discussion of the detection results of three insulating materials.The main research work includes:(1)The pure sulfur hexafluoride gas and sulfur hexafluoride gas with different water contents were experimentally measured by terahertz time-domain spectroscopy,and the absorption spectral characteristics of pure sulfur hexafluoride gas in the terahertz band at different temperatures were explored.Induced changes in the absorption spectrum of sulfur hexafluoride gas.Based on the least squares fitting,the relationship between the absorption peak value of sulfur hexafluoride and temperature is linear,and the quantitative detection of gas concentration is realized by combining with the ideal state gas equation.At the same time,the absorption coefficient and refractive index of sulfur hexafluoride gas with different water contents were obtained,and the absorption effect of moisture in sulfur hexafluoride gas on terahertz waves was studied.The water content is inferred,and the quantitative detection of the water content in the sulfur hexafluoride gas is realized.(2)The pure transformer oil and transformer oil with different copper contents were experimentally measured by transmission terahertz time-domain spectroscopy system,and the time domain,absorption spectrum and refractive index of pure transformer oil and transformer oil with different copper contents were obtained..By comparing and analyzing the terahertz spectrum of the transformer oil,it is possible to quickly and accurately detect whether there is metal foreign matter in the transformer oil,thereby ensuring the safe operation of the power grid.In addition,the transmission terahertz time-domain spectroscopy system was used to carry out experimental measurements on transformer oils with different moisture contents,and the time domain,frequency domain,absorption coefficient and refractive index of transformer oils with different moisture contents were obtained.Absorption of Hertzian waves.According to the absorption coefficient of transformer oil with different moisture content,the amount of water content can be inferred reversely,and the quantitative detection of water content in transformer oil can be realized.(3)The transmission terahertz time-domain spectroscopy system was used to detect the silicone rubber composite insulators with different aging times,and the time domain,frequency domain,absorption coefficient and refractive index of the composite insulators with different aging times were obtained.The aging state of the composite insulator can be reflected by the terahertz spectrum,which provides a new idea for the experimental study of the surface aging degree of the composite insulator.In addition,a terahertz experiment was carried out on the pore defects of composite insulators during production and use using a reflection-type terahertz time-domain spectroscopy system.By analyzing the terahertz spectrum with and without defects,it can be proved whether there are defects inside the composite insulator.