On-line Detection Of Contact Meshing State Of High-voltage Switch Cabinet Circuit Breaker Based On Image Processing

High-voltage switchgear breaker is an important protective device in power system,meanwhile contact meshing state detection is an important part of fault diagnosis of circuit breaker.In order to solve the problems such as high voltage and electromagnetic shielding environment of circuit breaker,difficult to extract the target contour of static contact of circuit breaker,large installation error of measuring equipment,thesis designs a data transmission method based on wireless communication,a new sub-pixel edge detection method based on active contour model.A high-precision meshing state detection system for dynamic and static contacts is implemented by designing a meshing state calculation method combining position calibration and ellipse correction.Aiming at the difficulty of signal transmission in the environment of live metal shield of switchgear,the feasibility of wireless signal transmission is analyzed based on the characteristics of electromagnetic wave propagation.The transmission reliability is verified by signal transmission experiments.The HTTP protocol is used to transfer the real-time data such as device control data and image data,while the message queue protocol is used to manage the periodic data such as device monitoring data.A convenient and reliable mechanical structure and control circuit are designed to solve the problem of equipment installation in narrow space to realize stable and reliable signal transmission.In order to solve the problem of low precision in object contour extraction,a subpixel edge detection method by Zernike moment is designed on the basis of pixel precision edge detection,sub-pixel contour is extracted as initial contour.Based on SNAKE Active contour model iterative algorithm,the ellipse contour with high accuracy is obtained,then transformed into a single pixel ellipse contour by iterative thinning algorithm,which is used as the target contour of meshing state estimation.Aiming at the initial error of camera installation,the transformation matrix of image and world coordinate system is obtained by camera calibration.The initial position error is obtained by installation position calibration.Based on the inverse perspective transformation matrix obtained from position calibration,the target contour is ellipse corrected.Also the accurate pixel coordinates of feature points are obtained to improve the precision of meshing state detection.On the basis of the visual inspection system designed in thesis,the inspection platform for the meshing state of switchgear is built.The reliability of the measurement equipment is verified by 10KV-35 KV high voltage test and instant pressurization test.Taking the scratch position of the static contact which represents the actual meshing state as the measuring object,the accuracy of the depth measurement is ± 1mm and that of the medium repeat measurement is ± 1mm.These tests verify the accuracy of the measuring system.