| With the rapid development of the power system and the advancement of urbanization in China,higher requirements are put forward for the power supply capacity and reliability of the distribution network.1OkV transmission line is one of the main components of the distribution network.During the thunderstorms,the distribution lines and power distribution equipment are often damaged due to lightning disasters.The installation of zine oxide arresters(MOA)is one of the effective methods to prevent lightning strikes on distribution lines.However,in the actual operation processes,the MOAs often suffer from insulation damage or aging,and in severe cases,the MOAs will be thermally melted,crackedt and exploded.Therefore,it is of great significance and engineering practical value to study the electro0thermal characteristics of the MOAs in distribution networks.In this paper,the distribution network lOkV MOAs are studied.Firstly,according to the electro-thermal coupling model,the heat transfer process of zinc oxide arresters is studied.The power loss of ZnO resistors in different current sections is discussed and utilized.The electro-thermal characteristics of zinc oxide arresters are analyzed by using the heat balance diagram,and the factors affecting the thermal characteristics of zinc oxide arresters are summarized.Then through the comparison of different MOAs electro-thermal analysis methods,the finite element simulation software COMSOL is used to simulate the electro-thermal characteristics of MOAs,and the two-dimensional axisymmetric model of the 10kV gapless MOA is established.The operation flow of MOA electro-thermal coupled multi?physics simulation in COMSOL is expounded in detail.The electro-thermal characteristics of the MOA in operation are simulated by lightning current,large current,square wave current,and repeated lightning strikes,The heat and heat dissipation characteristics of the tested arrester under different conditions have been obtained.The maximum operating temperatures under diflferent ambient temperatures have been obtained,when these temperatures are exceeded,the arrester will quickly fall into thermal runaway.Finally,the simulation results are verified by experiments.At the same time,the combined pressure test of the 10kV belt gap MOA is carried out,and the power frequency freewheeling characteristics of the arrester of this type under different pollution concentrations are obtained.According to the simulation and tested results,some specific suggestions for improving the thermal characteristics and stability of MOAs are given.The research work in this paper has certain reference value and guiding significance for the selection,design and production of MOAs. |
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