| In recent decades the demand of power supply has been enormously increasing due to the fast growth of economy. As to the requirement of power system reliability, decreasing the probability of power failure on transmission lines, shortening the time to recovery would pose a threat within power system. O ur past operation experience has demonstrated that lightning-caused faults to overhead transmission lines is the primary factor which affect the reliability of power system and how to reduce the lightning trip-out rate is still the focus of the entire power system. Although lightning protection system has come to realization of high efficiency, economization, and refinement through transforming and updating, however, lightning protection of overhead transmission lines remains technological challenge in today's world.Limiting by means of monitoring, early lightning parameters were exacted from the department of meteorology. Thus lightning activity and lightning frequency could only be represented in the areas where transmission lines pass through on thunderstorm days and hours. Thanks to Wuhan Branch. C hinese Academy of Sciences, it established the National Lightning Location System around 2007. This system could accurately obtain the cloud-to-ground(C G) lightning density of the line corridors at different district. As of now, rough evaluation of transmission line lightning protection could be drawn according to Lightning strike data of power line corridors. Yet the Lightning location system has position error inherent of a few hundred meters, and it could not identify the accurate strike location of one-time CG lightning(it could be ground wire, power lines or simply the ground). Therefore, it could not meet the expectation of precision. Hence, how to accurately acquire lightning strike data from transmission lines has become further challengeable and crucial. This project carries out the study of monitoring of lightning strike on transmission lines, the identification of lightning strike types in order to achieve more scientific fundamental data, thus to overcome the technological bottlenecks of the deficient performance of the previous system, and it has significant meaning in reducing lightning trip-out rate.The component of this project is listed as following:Firstly, Come up with categorizing types of lightning strike via studying of models of lightning strike, transmission lines, power-poles and insulators; constructing simulating models of lightning ground wires, power-poles and transmission linesSecondly, from the method of categorization above, method of lightning strike identification is proposed based on S-transform.Then, introduce the working theory of Rogowski Coil, proposes by using the method of integral compensation in calibration of distortion in low frequency. Design the associated hardware circuits, attests the validity through experiment.Propose the method of using high- voltage coupled energy-obtaining + lithium cells as power supply instead of coupled electromagnetic energy-obtaining. In addition, design charge management and protection circuit, the experiment shows the minimum startup current could be as low as 20Amps; design the scheme of FPGA data collection and GPRS data transmission, propose the scheme of redundant communication a nd this could solve the problem of data congestion and data lost.At last, according to the analysis of the performance during engineering application, verifies that distribution law of transmission lines and lightning strike fault poles are closely relevant, and the result is an important guidance to lightning strike prevention. |
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