Research On Sag Calculation Of Power Line Based On Image Processing

Sag of the transmission lines is one of the main indexes for circuit design, running and maintenance. It directly impacts on the safety and stability of the operation. A new method about sag calculation based on image processing was proposed in this paper in order to calculate sag conveniently and real time in power line inspection.In the paper, the overhang mechanics state about the power line of the isolated-span is researched, and the catenary equation and positive, oblique parabolic equation of the overhead power transmission line is deduced.Then the field of their application in the sag calculation and the image of power line inspection is discussed. Indicating the line state accurately, the catenary equation can do some mechanics calculation like the sag through extracting the parameters of suspension chain curve in the image. And the characteristics of the power lines in digital image is studied, and reached a conclusion that the draw median filter and canny operator is the suitable calculation about the image smooth processing and edge detection algorithm through comparing. Then the correction of space plane by DLT is researched.It makes image which obtained askance equivalent to the one taken in front of the object.And then indicating the application of this method in correction of image of power line inspection.A sag calculation method of certain overhead power line is infered from equilibrium equation of a small element of catenery. When the span of overhead line is certain, the line's overhang state can be determined just demanding an independent variable. Through analyzing sectional image and deducing the independent variable from the overhang state of the overhead lines, the entire level catenery can recovered from the catenary-segment, and then the sag of the overhead lines with certain span can be obtained. The complete flow diagram of the sag calculation method based on the analysis of sectional image is showed in the paper. Then the advantages and practical significance of the method are pointed out through comparing with existing methods.The simulation experiments are carried on to two kinds of lines separately which are pensile point equal altitude and unequal altitude. The experimental results show that this method can restore the complete line curve properly and calculates the sag.The sag calculation method in the paper based on sectional power line image analysis provides a quick and effective means for sag calculation problems in inspection of overhead lines.