Research On Visible Light/solar-blind Ultraviolet Dual-spectrum Corona Detection Technology

With the expansion of the national grid's construction scale and the increase of voltage levels,the phenomenon of corona discharge,which is caused by the equipment wear,has become more and more popular,so it has significant meanings to detect the corona discharge signal of the transmission lines and substation equipment in time.This paper developed a prototype of dual-spectral solar-blind UV corona detection system and researched the photon counting algorithm of solar blind UV on hardware platform.Therefore,three goals in solar blind UV corona detection including extending dynamic range of UV image,improving precision of photon counting and realizing the regular work of the system in a low illumination environment have been achieved.Firstly,this paper developed dual-spectral solar-blind ultraviolet corona detection hardware system including device selection of UV ICMOS according to the needs of corona detection and the improvement of miniaturized hardware circuit.Secondly,in view of the problem that the CMOS image sensor in the UV ICMOS module sacrifices the contrast for the wide dynamic range,the U-V image is linearly corrected and enhanced with the platform histogram equalization algorithm.Thirdly,to realize the system work day and night,the image registration algorithm and the image fusion algorithm of the UV images and the visible light image are adopted.And the experiment results demonstrate that our UV ICMOS can achieve normal imaging from solar blind UV signal range of 10-18W/cm2 to 10-9W/cm2 under 5×10-3lux illuminance.Fourthly,aiming at the goal to improve precision of photon counting,this paper developed the solar-blind UV photon counting algorithm based on the system hardware platform and designed the photon counting high frame rate algorithm,which increased the system frame rate up to 390 fps,to ensure the full sampling of image intensifier screen.According to the analysis of the causes of error caused by the traditional photon counting algorithm,this paper proposed a time-based diffuse circular photon counting algorithm.The experiment results show that the algorithm is proved to be superior to other traditional photon counting algorithms.Finally,the algorithm is achieved on the FPGA platform hardware and the photon counting effect was tested and evaluated.The test results show that the time-based diffuse circular photon counting algorithm can perform accurate solar blind UV photon counting,and the hardware implementation is satisfactory.