| Thunder is caused by natural climatic conditions,which can cause great harm to the power system.The lightning strike rate is an important parameter to test the lightning protection capability of power transmission lines.Reliably reducing the lightning trip rate is a common goal pursued by many researchers in the field of lightning protection.The process of causing a lightning trip accident is divided into four stages:first,the lightning invades the power system;secondly,the lightning strikes the voltage wave to cause the insulator to flash;then,the flashing arc creates a short circuit fault;finally,the circuit breaker trip causes the system to be powered down.The solid-phase airflow arc-extinguishing lightning protection gap is an external-energy arc-extinguishing device.The basic idea of the design is that the arc-extinguishing device generates an arc-extinguishing signal during the flashover phase of the insulator and triggers the arc-extinguishing gas pellet to generate high-speed airflow,and the high-speed airflow makes The arc is deeply suppressed to prevent the system from causing a short circuit fault.According to the above concepts,this paper provides theoretical research,modeling and simulation,numerical simulation,experimental analysis and other methods to provide important research results for the research,upgrade and improvement of solid-phase airflow arc-proof lightning protection gap,among which the main work is completed.Have:1.According to the theory of arc energy balance,the MHD magnetic:fluid model and the mayr arc model are theoretically studied.The two models can effectively explain the mathematical process and physical meaning of arc formation,stable combustion and extinction process2.The 110kV transmission line insulator model and arc extinguishing device model were built on the COMSOL MUTIPHSICS software platform.In the theory of MHD magnetic fluid,it can be considered that the arc is formed because the two ends of the gap provide Joule heat to the arc column,so that the internal energy of the arc increases,the temperature increases,the conductivity increases,and the arc extinguishing process is the conduction,convection and radiation of the arc itself.The heat dissipation is greater than the Joule heat at both ends,so that the internal energy of the arc is reduced,the electrical conductivity is weakened,and the dielectric strength is restored.3.Increasing the airflow speed of the arc extinguishing device is the main way to enhance the heat dissipation of the arc convection.To some extent,improving the gas production rate of the arc extinguishing gas pellet has positive significance for extinguishing the arc and suppressing the arc reignition.4.The experimental platform for setting the arc-proof lightning protection gap of solid-phase airflow is established.The U50%,volt-second characteristics,insulation mix ratio,arc-extinguishing response time and arc-extinguishing airflow speed of the arc-extinguishing device are determined.According to the power frequency high current arc extinguishing test,the effectiveness of the device to extinguish the power frequency high current short circuit arc is verified.5.A solid-phase airflow arc-extinguishing model was built on the PSCAD/EMTDC software platform.The arc-extinguishing response time and power dissipation two control parameters determine the ability of the device to extinguish the arc,cut off the short-circuit fault,and suppress the re-ignition of the arc.6.According to the actual situation of the line,some suggestions for the installation and use of the arc-breaking lightning protection gap of the solid-phase airflow are proposed. |
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