Temperature Field Modeling And Thermal Analysis Of Medium Voltage Switchgear Based On ANSYS

As the key electrical equipment of the distribution network,whether the stable operation of the medium voltage switchgear directly affects the safety of the power grid system and user equipment.As the current cost of urban construction land is getting higher and higher,medium voltage switchgears are developing in the direction of miniaturization,modularization and intelligence,which will cause the internal heat dissipation environment of the switchgear to be worse,and the temperature rise of local areas in the cabinet may easily exceed the standard.Bringing a severe test to the electrical and mechanical properties of the switchgear products themselves.Therefore,it is of great engineering value and practical significance to carry out in-depth research on the heating mechanism and temperature rise performance of medium voltage switchgear.At present,most of the researches on the temperature rise characteristics of switchgear at home and abroad are only conducted for local components,and the comprehensive effects of the overall heat loss and temperature rise characteristics of the switchgear are rarely analyzed.Therefore,it is necessary to use ANSYS software to model the temperature field of the medium voltage switchgear and perform thermal analysis.The main research contents and conclusions of this article are as follows:Firstly,the temperature rise effect and thermal equilibrium mechanism of medium voltage switchgear are analyzed according to the principles of heat generation and heat dissipation in the inner conductor of the cabinet,and the theoretical calculation model of eddy current field and steady state temperature field based on finite element of medium voltage switchgear is derived.Secondly,based on a certain type of 12 k V medium voltage switchgear,its three-dimensional model was established and the model was simplified.Among them,considering the influencing factors of the contact resistance of the movable conductive parts and the surface heat dissipation,the simplified principle of the plum blossom contact model is proposed,and the plum blossom contact calculation model is simplified;in order to simplify the thermal calculation of the complicated internal structure of the vacuum circuit breaker,Based on the concept of vacuum circuit breaker equivalent resistance,a simplified calculation model of vacuum circuit breaker was established based on the influencing factors of vacuum circuit breaker resistance and surface heat dissipation area.Carry out the simulation calculation of the loop resistance value for the simplified calculation model of the whole medium voltage switchgear,and make a comparative analysis with the measured value of the loop resistance of the medium voltage switchgear to verify the correctness of the whole simplified calculation model of voltage switchgear.Subsequently,the eddy current field calculation at 1.1 times the rated current of the power frequency was performed in the Ansys Maxwell module to obtain the ohmic loss of the cabinet and the conductive circuit,and this loss was imported into the overall steady-state thermal analysis module of the medium voltage switchgear The heat source of the switch cabinet calculates the comprehensive heat dissipation coefficient of the cabinet,and iteratively calculates the convection heat transfer coefficient of each component of the conductive circuit.Finally,the ANSYS steady-state thermal analysis module is used to calculate the temperature field distribution of the components of the medium-voltage switchgear cabinet and the conductive circuit,and the corresponding temperature rise values can be calculated accordingly.In order to verify the feasibility of the temperature field model of the 12 k V medium voltage switchgear established in this paper and the accuracy of the thermal analysis calculations,all temperature rise type tests of the same type of 12 k V medium voltage switchgear were conducted at the Suzhou Electric Power Research Institute.The temperature rise test values of the components of the conductive circuit and the cabinet obtained by the test are consistent with the results of the simulation calculation based on the built model and the values are very close,indicating that the temperature field modeling and thermal analysis of the medium-voltage switchgear based on ANSYS in this paper The calculation is feasible and effective,and can provide theoretical and technical support for product development and design improvement of similar switchgear,and has good engineering application value.