Research On The Technology Of Porcelain Insulator Deterioration Diagnostic Based On Infrared Thermal Detection

Insulators are the only electrical insulation and important structural supports on overhead transmission lines and must have go od insulation and mechanical properties.However,due to the different expansion coefficients of each phase,porcelain insul ators are affected by electromechanical load and extreme weather during long-term outdoor operation.So it’s easy to reduce the insulation resistance or generate harmful stress,and produce low or zero-value insulators.When the flashover discharge occurs,it may cause serious electrical accidents,with the iron cap bursting,and the insulator or the wire falling off.As the voltage level of transmission lines in China continues to increase,the grid accident rate caused by the deteriorated insulators has increased year by year.In order not to affect the operation of the transmission line,the insul ator should maintain the original insulation level.Therefore,how to perform the deterioration detection of the insulator string more safely and effectively becomes an u rgent problem to be solved by the power department.Infrared fault diagnosis technology,based on good image segmentation a nd recognition,has been applied more and more widely in fault identification of power equipment,such as insulator.However,due to the impact of blind area and complex images,the accuracy of existing detection methods and image processing methods is low.To solve the problem,starting with the theoretical simulation and experimental analysis,the infrared detection technology of porcelain insulators is further studied.In the simulation,the voltage distribution and heat law of the insulators are analyze d by selecting the voltage difference and temperature difference data at the typical p osition.The cause of the blind area of the deterioration diagnosis and the factors such as the distribution voltage,the warning temperature difference,the deterioratio n location are analyzed.Regulating effect of changing environmental humidity on blind a rea range is also analyzed.Based on this,a number of high-voltage simulation tests were carried out.Using the method of correcting temperature,the insulation string temperature characteristics of different deterioration conditions under different h umidity are analyzed and verified.According to the results,the insulation deterioration diagnostic criteria,based on the temperature difference of the blind area,is pro posed.The watershed algorithm is combined with the preprocessing operation and the se gmentation operation,based on the morphological feature.It is also combined with the angle correction operation based on the inclination judgment.By setting the intern al marker to control the segmentation,the positioning and selection of the insulator r egions of the insulator strings with different inclinations under the different voltage levels can be realized.Finally,combined with the BP algorithm,which has the ad aptive learning rate,multiple normalized cap and disk temperature data are used as the input parameters.Diagnostic work for deteriorated insulator,including blind area i nsulators,can be achieved.The above method was applied to the deteriorated insulat or intelligent diagnosis system and its effect was examined.The results show that the image segmentation method in this paper is more adaptive,the effect is better and the program runs faster.Meanwhile,the deterioration diagnosis method based on the te mperature difference characteristic of the blind area has great advantages.It can significantly reduce the interference of the deterioration position and the detection blind area range.It also has a great effect on improving the accuracy of the infrared detection method of the porcelain insulator,and has practicality.