The Design Of 110kV Three-position Switchgear Based On The Finite Element Analysis

With the increasing electrical equipment capacity and improving transmission voltage grade,higher requirements on the performance of electrical equipment are claimed.With the rapid development of power system,the application amount of GIS closes a large increase.In order to satisfy the needs of users in high reliability,small volume,light quality and free maintenance,the volume of electrical equipment is increasing miniaturized and the compact structure is getting more and more complex,which put forward higher requirements on the insulation performance.First of all,using the finite element analysis method,the paper calculated the electric field distribution of 110 kV TPS,the calculation results showed that when 550 kV power-frequency voltage was added,the maximum electric field strength appeared on the shielding ring of the supporting insulator,which surpassed the allowable field strength of 22kV/mm.The optimization was accomplished by changing structure parameters of shielding rings,and the results showed that the electric field of optimized TPS distributed more uniformly.The TPS passed the 1min power-frequency withstand voltage test and lighting impulse breakdown test with filling SF6 gas under the condition of 0.35 MPa,which fully meet the national standards.The optimization design satisfied the standard requirement and operation reliability,enhanced the insulation structure.Secondly,in order to explore the heat and loss of TPS in a further step,the finite element analysis method was used in this paper to calculate the temperature rise distribution and establish the heat and loss calculation model of 110 k V TPS with three-dimensional electromagnetic field,flow field and temperature field.The convection heat transfer coefficient changing conditions of internal SF6 gas was analyzed under different pressure,bonding the eddy-current loss and resistance loss of TPS current-carrying conductor and enclosure,the temperature distribution was obtained.The calculation results showed that when TPS is horizontal,the internal temperature distribution is S type with higher temperature on the top and lower temperature on the bottom.The three-dimensional isothermal distribution of TPS was showed in the calculation in the finite element analysis,its miniaturization,low-pressure design showed great value in engineering application.Furthermore,the paper compared the simulation calculation and temperature-rise test of TPS,the results indicated that the calculation and the test distribution trend was the same.Incorporation of the optimization algorithm and the finite element method,the structure parameters was optimized with multiple sets of simulation results of temperature distribution.The optimized model was rebuilt and the temperature distribution calculation was simulated repeatedly,the result error was within acceptable range and optimization design measured up the national standards and insulation requirements.In the end,the VFTO of 110 kV TPS was studied,the opening and closing bus-charging current of TPS was calculated and simulated and the characteristic of internal operating overvoltage was found.The study showed that the cumulative effect of VFTO should be noticed when TPS is in long-time running situation and the further insulation performance requirements of switchgear were proposed.