Development Of Transmission Line Sag Online Testing System Based On Embedded Image Processing

Sag is one of the important parameters of the operation and maintenance of transmission lines and it has a direct impact on the safe and stable operation of transmission lines. If sag is too large, it is prone to dance or cause discharge and tripping accidents by wind action; if sag is too small, lines are prone to occur line off due to the presence of tension power. Therefore sag will affect the normal operation of transmission lines adversely if it is too large or too small. Sag should be controlled within a reasonable range.To ensure operation of the transmission line and the crossing equipment or facilities safely, we need to measure the power lines sag real-time and monitor periodically. Therefore, the paper on the results of the work of previous innovation and reform, monitor transmission lines sag real-time online by embedded system hardware platform, Linux operating system and image processing algorithm.In this paper, starting to analysis the status quo at home and abroad from power lines sag calculations, understand the development of related technologies and applications, combined with critical issues of the research methods, design the overall scheme of the research methods. Firstly, install the image acquisition and processing device on ARM platform at the tower pole and set the transmission line parameters, extract the transmission line image by the way of human-computer interaction to overcome the difficulties of the separation between transmission lines and background, extract some corner of the tower pole as control points for image correction. When measurement the sag online, the first is image pre-processing and image correction and separate transmission lines and background automatically in a given neighborhood; then calculate line sag using the corresponding formulas based on line conditions; finally judge sag in the safe range, if otherwise, alarm to the monitoring center.The system development has main two parts: embedded operating system platform and algorithm. Operating system platforms including: selecting the right embedded processors and operating systems, computing and selecting camera parameters, selecting image storage and wireless transmission, integrated development of QT Creator; there are algorithms of pre-processing、image correct and rear edge of transmission lines, extraction power lines, measurement sag of transmission lines online, the realization of the function of communication.Finally, the actual test proves that the system can detect power lines sag online stably and reliably. It meets the design requirements.