Research On The Embedded System Of Image Acquisition For Ultraviolet Corona Detection

It is well known that the corona discharge of power system not only leads tosubstantial loss of power, but also could damage the insulator resulting serious incidents ofpower system. Therefore it is necessary to conduct corona discharge detection, localizationand assessment to reduce the loss of the power system. The ultraviolet imaging method as anew and fashionable charging detection technique is being used increasingly in thedetection of the corona discharge.Computer image acquisition technique has been widely used. However, it hasdisadvantages of complex structure, high cost, large size and high power consumption. Asthe fast development of the embedded system recent year, it is becoming popular trendadopting embedded system of image acquisition with intelligent control and intelligentprocessing functions. Applying embedded system into image acquisition will overcome theshortcomings in computer image acquisition.In this thesis, the embedded image acquisition system based on ARM and Win CE isstudied in details, with the hardware components, the data capture drivers and theapplication software of the image acquisition as the research subject.1. The ARM hardware platform, the kernel module of the Windows CE embeddedoperation system and the module of the file system are systematic analyzed. The operationmode of the microprocessor, the internal storage and the interrupt system in the ARMplatform, and the architecture, the memory management method and the file system moduleof the Windows CE embedded operation system are studied intensively. By the analyses,the scheme of using ARM+Windows CE is presented which meets the requirements of theimage acquisition, image display, image storage and the postmortem analysis for theultraviolet-imaging corona detection system.2. The embedded image acquisition hardware platform is designed, including thedesign of S3C6410circuit module, the image acquisition module and so on. According tothe requirements of the video signal acquisition of the ultraviolet-imaging corona detectionsystem, the camera pixel clock, the line synchronization, the field synchronization and thedata signal of the video-signal decoding chip of TVP5150and S3C6410are configured, sothat the connection between the control signal and the data signal can be realized byTVP5150and S3C6410on the hardware links. The image acquisition module hardware hasbeen designed. According to the function requirements of the system, the embeddedhardware platform is designed in detail, including SD card storage circuit, the luminance and focus adjustment circuit, the image display circuit, the touch screen circuit and so on.The luminance and focus adjustment circuit of the camera is driven by the PWM module ofA3969and S3C6410, and the display circuit is realized by the display interface of CH7026and S3C6410.3. The software of the image acquisition of the embedded system is developed,including the driving program of the video signal encoding chip and the applicationprogram of the image acquisition. According to the overall scheme of theultraviolet-imaging corona detection system and the hardware system, the camera drivingprogram in Windows CE and the architecture of the image acquisition with DirectShow areanalyzed. According to the working time sequence of TVP5150, the pixel clock, the linesynchronization and the field synchronization are set up in the driving program functions ofCAM Init and CAM Open. The capture application program of DirectShow is executed stepby step, the calling relationship between the application program and the driver layerfunction is analyzed, and the application program of the image acquisition suitable for thissystem is optimized.The constructed ultraviolet corona detection system, adopting the design in this thesis,is with good performance in the detection of the ultraviolet radiation band of240-280nm.The radiation is received by an ultraviolet CCD and displayed by a display device. Thecorona and the ultraviolet radiation during the surface discharge can be recorded, processedand analyzed, and the situation of the power system can be then evaluated. The discharge ofthe power system can be directly observed, which is helpful for the personnel on-site tolocate the discharge position quickly and accurately, and to evaluate the harmful level of thedischarge with the dynamic video recording.