Study on Thermal Performance of Natural Oil Circulation Power Transformer Winding
|School||Hebei University of Technology|
|Course||Thermal Power Engineering|
|Keywords||Power transformers Test Thermal Characteristics Natural circulation|
Oil-immersed transformer with good heat dissipation, low loss, large capacity, low prices. Power line running most of the power transformers oil-immersed transformers, of which more than 80% natural oil circulation cooling. Natural oil circulation transformer coil set guide plate is now widely used as a cooling structure. However, lack of knowledge about its coil thermal characteristics. Respectively, on a variety of factors of the natural oil circulating level of the oil clearance size of transformer coils coils Have oriented sets, the number of guide zones and the direction of the oil flow on the the coil temperature distribution, especially on hot temperature investigated were studied and numerical simulation. Oil-immersed self-cooled, air-cooled transformer coil shrink the size of the level of the oil passage, so that the oil circulation flow reduction, deterioration of coil heat exchanger, and thus the average temperature rise of the coil, copper coil temperature difference between oil and oil were higher than the average temperature rise greater the corresponding value of the size of the oil passage. Set guide in the coil structure, effectively eliminates the dead space of the oil flow in the coil, the coil surface convective heat transfer from improving the overall cake to obtain sufficient cooling of each line, so that the average temperature rise of the coil, the average copper The oil temperature difference is lower than unguided and coil decline in average temperature rise is directly proportional to the increase of the amplitude of the coil within the guide area number. The average oil temperature rise also showed a downward trend. Hotspot location is not located in the most end portion of line cake. Hot spot temperature rise with the number of guiding area, the complex variation exists between the level of the oil passage size and other factors. Horizontal oil passage is reduced, increasing the number of guide zones Mobile hotspot locations corresponding to the end portion of the coil. Natural convection in a horizontal flow channel can not be ignored, and the effect is very complex. The vertical oil channel flow inward from the outside of the vertical oil passage when the oil flow of the coil end portion of the guide region, and the line end portion of the cake than in the opposite direction when the oil flow in the temperature rise of approximately 10% to 20% lower. In the same time, the the coil hottest spot temperature is also lower than in the direction opposite to the direction of the oil flow, and its position is moved corresponding to the lower part of the coil. The number of guide zones is constant, the number of oil passage to reduce the level of the end portion of the guide zone can improve the heat transfer conditions within the area, to reduce the temperature rise in the region hotline cake. But the average temperature rise of the coil and the average copper oil temperature difference increases. , Increases the differential heating center of the coil and the height of the center of the cooling cycle the driving force increases, the circulating oil flowing through the coil flows a corresponding increase of the temperature rise of the coil showed a downward trend. Hebei University Graduate Thesis oil-immersed self-cooled, air-cooled transformer coil set oriented structure is conducive to reducing the average temperature rise of the coil. But the coil hot spot temperature rise by a coil oriented interval number, Each guide wire cake, the direction of the oil flow, the level of the oil passage size and external cooling conditions and other factors. The level of the coil cooling oil gap size. The direction of the oil flow, the external cooling conditions, as well as the number of stomach-oriented area located and the number of guide lines in the region cake will be resistance to oil flow, oil temperature, and then the oil viscosity and circulating oil flow will have a combined effect of, and . There is a very complex internal relations between the hot spot temperature rise. Therefore, the set-oriented area to take full account of these factors in order to get better cooling conditions.