Research On Deterioration Detection Method Of Insulators In High Voltage Transmission Lines

With the continuous improvement and upgrading of power grid technology,people have put forward higher requirements for the performance of power systems.In this situation,more and more insulators have been used in power distribution systems on a large scale,especially in the ultra-high voltage and direct current transmission systems that have been maintaining strong development in recent years.Since the performance of the insulator is directly related to the stability and continuous operation of the grid system,the mechanical properties and insulation properties of the insulator are particularly important.In order to better meet the domestic power development needs,the sophisticated and advanced teclinical methods are used to deeply explore and study the degraded insulator detection methods,which has great practical significance in improving the transmission line performance and real-time monitoring of insulation performance.At present,there are many methods for detecting deteriorated insulators under charged state at home and abroad,but there is no unified norm,convenient and reliable method.Therefore,this paper selects two methods of non-contact degraded insulator detection for spatial electric field distribution measurement and infrared imaging,and analyzes electric field distribution measurement method.And the feasibility of the actual detection of infrared imaging method,and the influencing factors of the two methods are tested and summarized,and the improved degradation insulator detection method is proposed for the insufficiency of the two detection methods.The main contents of the paper are as follows:(1)Establish a 220kV porcelain insulator string degradation test model;(2)Experimental study on the effect of electric field distribution measurement on the degradation of 220kV porcelain insulator string and its influencing factors,analyze the spatial electric field properties of porcelain insulator strings,and propose an electric field distribution measurement method based on sensitive insulators;(3)Taking the suspension porcelain insulator as the research object,the infrared thermal image detection and defect diagnosis technology of the deteriorated insulator were studied.The influence of different factors on the infrared thermal image detection of the insulator was analyzed.An improved infrared imaging detection method was proposed.The research shows that the maximum field strength of porcelain insulator surface appears in the air near the surface of the shed,and its electric field value decreases when it deteriorates.The influence of insulator degradation on its radial radial electric field component is most obvious,and its influence is related to the position of deteriorated insulator.The continuous deterioration of multiple insulators has a greater influence on the rate of change of the spatial electric field than the discontinuity.The electric field distribution measurement method based on sensitive insulator proposed in this paper can determine whether the zero-value insulator is contained in the suspension string of 220kV line by analyzing the electric field change rate of three porcelain insulators at the cross-arm end.The infrared imaging method can detect whether there is a deteriorated insulator and its position in the insulator string.The external meteorological environment factors have no significant influence on the insulator’s own heating condition,and the deteriorated insulator position and resistance have certain influence on its detection.In this paper,an improved infrared imaging detection method is proposed,and a numerical analysis:ethod is introduced to detect the deteriorated insulator.The actual verification on the spot shows that the improved infrared imaging detection method has higher reliability than the traditional method,and it is worthy of promotion and further research.