Study On Lightning Clearance Of Extinguishing Arc Based On Long Gap Arc Analysis

With the rapid development of industrialization,the global climate and environment have changed greatly,and the lightning activity tends to be frequent affected by the climate.Overhead transmission lines have long stood in the complex outdoor natural environment,and the probability of lightning strike has also increased.In order to ensure the safe and stable operation of transmission lines,experts and scholars at home and abroad have put forward various theories and technical means suitable for lightning damage protection of transmission lines,which have greatly improved the stability of transmission lines.However,the data show that lightning trip accident is still one of the main factors affecting the stability of power grid.This paper studies an arc-extinguishing clearance device for lightning protection of 220 kV overhead transmission lines.The device adds active arc-extinguishing unit on the basis of traditional "dredging" lightning protection technology--parallel gap,which can ensure that the subsequent are is extinguished while the lightning energy is dredged,and effectively protect the line safety.In this paper,the basic physical characteristics of arc and the energy process of arc column are analyzed through theoretical research.It is shown that the energy process of the arc column is mainly reflected by temperature,and the alternating process affects the change of temperature and radius.Under the action of external strong air flow,the energy dissipation can be accelerated and the energy balance of the arc column can be destroyed,and the high speed air flow can accelerate the transformation of the medium in the gap the medium strength recover quickly.By numerical analysis and the establishment of longitudinal blowing model,the process of arc extinguishing under the action of strong airflow is analyzed in comsol multiphysics simulation software.Simulation results show that the energy of the arc column is rapidly lost,the temperature drops rapidly,and the arc is effectively extinguished within 5ms without reburning.According to the experimental data,the U50%of the device and the optimum insulation mix ratio are determined to be 0.85,and the volt-second characteristic curve is drawn.To verify the arc-extinguishing performance of the arc-extinguishing gap,a high-current arc extinguishing test is also carried out.The test results show that under the condition of 40kA working frequency and high current lasting 120ms,the device can lasting 120ms,and no rekindling occurs in the subsequent time period.Finally,according to the case analysis of the pilot operation line,it provides a strong support for the reliability and safety of the device,and puts forward some suggestions for the improvement and popularization of the device at the end of the paper.