Research Of Loss And Thermal Studies In Box-type Substation

With the continuous development of China’s economy,transmission grid keeps expanding.Therefore the city network substation quickly covers the urban area.City network substation is located in the city center and assumes important power supply tasks.It develops towards miniaturization,land-saving and energy-saving,which brings the rapid development of box-type substation.Due to the structural characteristics of the box-type substation,it is prone to equipment safety problems caused by high temperature rise,which is more dangerous when the temperature is higher in summer.So a reasonable ventilation cooling program is needed to ensure the safe operation of the main transformer.In this paper,a box-type substation is taken as the research object.Using the experiment,theoretical analysis and numerical calculation method,and based on CFD numerical simulation technology,the box-type substation overall ventilation and heat transfer effect is analyzed through the magneto-flow-thermal coupling.This paper mainly focuses on the following issues:(1)The internal loss of box-type substation is analyzed.Electromagnetic calculation of a 7600 kVA dry-type transformer is done by the finite element analysis software.Its main flux,short-circuit impedance and leakage magnetic field are analyzed,and compared with the experimental value.The core loss distribution,load loss and additional loss distribution are analyzed;(2)Based on the theory of heat transfer and hydrodynamics,the internal heat generation and heat transfer process inside the transformer,high and low voltage control cabinet are analyzed theoretically.A numerical simulation is carried out on the temperature field and fluid field distribution of a 1600 k VA dry-type transformer under two conditions-no shell and shell.The simulation results are compared with the experimental values to verify the validity of the numerical calculation method.(3)Based on the design of a box-type substation,reasonable mathematical model and physical model are established.The influence of different outlet velocity on the temperature rise of the transformer and the effect of the whole ventilation and heat dissipation are analyzed by numerical simulation of the velocity field and temperature field.On the basis of the original model,the ventilation holes are added at the bottom and top of the box respectively.The temperature rise of the transformer,the whole temperature field and the fluid field distribution are analyzed to provide a theoretical basis for the built box-type ventilation and air flow.The position of outlet is fixed,the locations of the inlet and the height of the inlet are improved to study the changes of indoor ventilation flow and temperature field.The temperature field,velocity field and characteristic temperature are compared with each scheme,and their influences on ventilation and heat dissipation are analyzed respectively.A reasonable energy-saving design is summed up for the design staff to refer to.