Multiphysics Coupling Simulation And Experimental Verification Of 10 KV Zinc Oxide Arrester With Large Current Structure

With the rapid development of my country’s industry and technology,power users have an increasing demand for safe and reliable power supply.Lightning strikes are frequent in my country,and 10 kV distribution lines are widely distributed,with low dielectric strength and complex operating environments.Lightning strikes often cause 10 kV lines to trip,power outages,and equipment damage,and even cause 10 kV wires to break and fall to the ground,resulting in electric shock casualties.According to the statistics of power grid companies,power outage accidents caused by lightning strikes in distribution lines account for 21.91%of the total number of distribution network faults.The installation of line zinc oxide arresters can reduce the lightning strike failure of the distribution network.Judging from the field operation experience,the existing arrester has burst accidents from time to time.In the early stage,the State Grid Disaster Prevention and Mitigation Center found through tests that the thermal expansion of the resistor sheet during lightning strikes caused tearing of the glass ribbon,causing local electric field distortion and triggering internal insulation flashover.However,the influence mechanism of the current flow capacity of the entire arrester in the current research at home and abroad is still unclear.In order to improve the current flow capacity of the entire arrester and reduce the lightning strike failure rate of the 10 kV arrester,the simulation and experimental verification of the electrical-thermal-mechanical characteristics of the arrester under the action of current are carried out.1)This paper introduces the principle of multi-field coupling simulation calculation of the electric and heat of the arrester,and uses the COMSOL finite element simulation software to build the axisymmetric model of the zinc oxide resistor sheet and the traditional structure 10 kV gapless arrester,and conducts the electric-thermal-mechanical multi-physics model.Coupled simulation calculation,studied the distribution of electric field,temperature and stress of the arrester after 4/10 us high current impact,analyzed the weak links inside the arrester from the perspective of electric field strength,temperature rise,strain and stress of the internal components of the arrester,and summarized the influence Factors affecting the flow capacity of the entire arrester.2)The improved structure arrester proposed by the State Grid Hunan Electric Power Co.,Ltd.Disaster Prevention and Mitigation Center was analyzed,and the simulation results of the single-piece resistor sheet,the whole arrester,and different insulating cylinder materials were compared through COMSOL simulation calculation,and the traditional structure arrester was compared.By comparing and analyzing the strain and stress of the internal components of the modified structure arrester,it is found that the flexible structure of the zinc oxide arrester can significantly reduce the internal stress level,and the mechanism of the improved structure is expounded in detail.3)The simulation results of the zinc oxide resistor sheet and the arrester are compared and verified through the test.The single-chip resistor sheet and the entire arrester are subjected to a 4/10 us waveform and a large current surge test with an amplitude of 100 kA.The test passed the test.The results show that after the improved structure,the large current flow capacity of the whole zinc oxide arrester is improved,and the temperature change curve of the test product is basically consistent with the simulation results,which verifies the accuracy of the simulation model.The test shows that the structure of the existing 10 kV arrester is unreasonable,and the current flow capacity of the whole zinc oxide arrester is far less than that of a single piece of zinc oxide resistor,which is one of the important reasons for the high level of lightning strike failures.The internal structure of the arrester proposed by the center is helpful to improve the flow capacity of the whole arrester.The research work of the paper has certain reference value and guiding significance for the design and production of the arrester.