Research On Electromagetic And Thermal Problems Of Box Substation

The box substation has gradually replaced the traditional civil-powered substation with the characteristics of strong completeness,small size,beautiful appearance,reliable operation and simple daily maintenance.It has become an important power equipment widely used in the construction and transformation of the national power grid.The internal heating equipment of the box substation mainly radiates heat through the openings on the wall.Therefore,the good ventilation and heat dissipation structure is the premise for ensuring the safe and stable operation of the box substation,and has important practical significance for engineering design.This dissertation takes a model of ZBW-1000/35 box substation as the research object,and its electromagnetic field is analyzed by combining theoretical analysis and numerical simulation.The error between the no-load loss,load loss and analytical value is 3.63% and-7.8%,respectively,and the error is within the allowable range of engineering calculation.This research is based on the knowledge of heat transfer and fluid mechanics.The numerical calculation model of box substation is established based on the heat-flow coupling method,and the distribution of fluid field and temperature field in box substation is analyzed.The results show that the exhaust ventilation efficiency of the front air outlet of the transformer room is low,the ventilation of the inlet and exhaust vents of the same axial height of the low pressure chamber is basically the same.In order to optimize the dissipate heat in the low-voltage cabinet,the air outlet of the low-pressure chamber should be at least higher than the cabinet.In general,the relative error between the numerical simulation results of the temperature field of the box substation and the temperature rise test value is ?11%,which satisfies the requirements of engineering calculations.The research on the basis of the original scheme improves ventilation and heat dissipation structure,adjusts the arrangement of the tuyere of the transformer chamber,the height of the outlet center,and the location and area of the air inlet,and compares different schemes by the judging criteria which is the distribution of the fluid field of the box substation and the hot spot and average temperature rise of the important reference objects such as high and low voltage windings and iron core.The results show that the arrangement of the air inlet on the side and the air outlet on the front is better.The heat dissipation effect is ideal when the center height of the air outlet is Y=2.5m and the lower side of the air outlet is just horizontally aligned with the top of the upper transformer yoke.The position of the center of the air inlet should be kept facing the transformer iron yoke,and the heat dissipation effect is ideal when the center height of the air inlet is Y=0.25 m.At this time,the lower side of the air inlet is just horizontally aligned with the fan below the transformer.When the total area of the air inlet on the side of the transformer room is 1.2 times the area of the front air outlet,the heat dissipation effect of the box substation is better.The hottest temperature rise and average temperature rise of the low-voltage inner winding of the box substation were reduced by 16.1K and 12.8K through a series of adjustment schemes,the temperature drop reached 23.9% and 33.6%.A reasonable improvement method is proposed to provide reference for the engineering design of the same type of box substation.