Research Of High Voltage Transmission Lines Icing Condition Monitoring And Deicing Technology

The natural disaster, icing high voltage transmission line, is a widespread problem at home and abroad. In the extremely cold weather conditions, the wires are easily got frozen, which would cause interphase flashover and increase the wire tension and the bearing load of fittings, like pylons, etc. More seriously, it may cause accidents, such as wire fracture, tower collapse, grid cracking, and so on. As the construction and development of the big power grid in our country, the operating stability and security requirements of the power grid has been improved gradually. Therefore, the ice monitoring and deicing technology of high voltage transmission line have become one of the urgent problems to be resolved, in order to guarantee the ability of power grid to conquer icing disaster.At present, the deicing methods generally used in the world can be roughly classified as mechanical deicing, thermal deicing, passive method, etc. Among all the deicing technologies and methods for high voltage transmission line, the main evaluation basis for exploitativeness of the project is energy consumption, deicing efficiency, safety and scope of application. This dissertation mainly studies dynamic mechanical properties, thermal deicing process, deicing technology and deicing device, put forward the feasible deicing technology and method. All the chapters in this dissertation will talk about it in detail.The real time monitoring of the ice state is an important premise. Because of the diversity of the geographical conditions where icing lines locate and the randomness of the weather conditions, the ice monitoring of high voltage transmission line should be put into practice under different conditions. So, there are also many types of methods to monitor the icing condition. This dissertation firstly researched the intelligent monitoring method for the icing condition of high voltage transmission line. By awakening work method, many functions can be realized, like real-time warning of icing line, ice thickness monitoring, meteorological data query, on-site image remote monitoring, etc. It gives reasonable deicing methods for high voltage transmission line, and provides a reliable basis.The dissertation researches the mechanical properties of artificial freshwater ice, focusing on the experiments of compressive strength and elastic modulus, which provide the exact data for analyzing the icing parameters. The dissertation also researches the mechanical properties of icing wires and strength experiments on different cross-sectional icing wires, then, the conclusions about the strength level of glaze on different cross section of icing wires under different temperatures have been drawn.In terms of thermodynamics, the dissertation analyses the nonlinear process of high voltage transmission line deicing. Because the thermal resistance when deicing is difficult to confirm precisely. The dissertation applies intermediate value theorem, calculates the deicing time of icing wires under the condition of the thermal resistance of limit fluid, and work out the average deicing time. The analysis of relative error shows that the error on the average deicing time is less than 5%.On this basis, this part focus on analyzing the ice thickness in the wind load condition and the effect of convective heat transfer coefficient on average deicing time. The simulation result shows average deicing time increase as the ice thickness and convective heat transfer coefficient increase, which provides the theoretical reference for thermal deicing technology of high voltage transmission line.The dissertation makes the vibration model of icing wires, analyses the feasible displacement boundary condition for the deicing project of high voltage transmission line, and investigates dynamic response of glaze wire region under different displacement excitation, in which frequency rate ranges whithin 0-2kHz. According to the strength level of glaze wires, the dissertation concludes the reasonable displacement excitation parameters for deicing technology of high voltage transmission line.The dissertation puts forward and researches coupling resonance deicing technology of high voltage transmission line, calculates the natural frequency of cylindrical, oval and sectoral glaze wires, and concludes the variation tendency as glaze thickness, constraint length, semimajor axis of ellipsoid, sectoral radius changes. The dissertation also analyses, investigates and compare stress amplitude in glaze wire region, which proves this method is feasible and provides the reliable theoretical reference for coupling resonance deicing project of high voltage transmission line.In the terms of ultrasonic deicing of high voltage transmission line, the dissertation researches the ultrasonic deicing technology and method. It put forward an contact-type ultrasonic deicing method, researches the dynamic response of glaze wire region in ultrasonic wave.the results show that the stress amplitude in glaze wire region could reach the crushing strength in calculation parameters, which proves the feasibility of the theory. On this basis, the dissertation fatherly concludes the best deicing frequency of ultrasonic wave for high voltage transmission line. The dissertation puts forward two types of horn which are used in the ultrasonic deicing for high voltage transmission line. The simulation analysis shows the maximum vertical displacement of perforation vertical horn could reach the displacement technical parameters which is used for ultrasonic deicing. At last, the dissertation gives the structure design of the ultrasonic deicing device for high voltage transmission line.