The Calculation Research Of Unsteady State Temperature Field And Age Of Natural Oil Circulation Large Power Transformer With Oriented Structure

Oil immersed transformer is widely used in power transmission because of its good coolant,low wastage and price, large capacity. At present, in oil immersed transformers natural oilcirculation is used at about 80%. In order to solve the noise-disturbing-citizen problem andremove the static electricity in oil flow, natural oil circulation has been wildly used in largepower transformer. A direct result of adopting natural oil circulation is to increase the temperaturedifference between copper and oil. So the heat elimination becomes more serious.Power transformer is the important equipmen of the electric power system. It has the importantinfluence to the electrical powersystem.,and moreover its capacity bigger, the heat elimination is moreserious.This paper sets up the mathematic model of heat transfer and oil flow, and finishes thecalculation of oil flow distribution and temperature field of winding in large natural oilcirculation power transformer with oriented cooling structure. The work of this paper will offerreliable reference data which can guide the design and the operation of the transformer and helpimproving the transformer design. In this paper, oil flow is described as one-dimension flow, andcalculated with Newton-Raphson method. According to the characteristic of the powertransformer, the temperature field of winding can be described with a partial differential equationin a cylinder coordinate system.In this articl,the calculation of the top temperature rice is based on the latest Loading guidefor oil-immersed power transformers.It has considered the stable state and the non-state state temperature rice. It used the newest stipulation oil index and the winding index that caused thecomputation to be more accurate.This article has compiled comprehensive software that can calculate the temperature field ofwinding and the length of life of the power transformer. This program is suitable for natural oiloriented circulation transformer. This program is not restricted by the number of ducts andoriented areas in windings and the size of duct and winding. It is not restricted by the number ofwindings in transformer either.To load periodogram which assigns, the program can computation hot spot temperatureandrelative aged value. When normal cyclical load and first aid cycleload is given, with the slot andthe initial continuous loading,it may calculate the corresponding time compartment the load value.Says from the certain significance,the computational methodmay this article can instruct thetransformer the structural design, enhance thetransformer the thermal properties and thetransformer theservice life, improve transformer movement condition, reduc the accidentoccurrence, thus brings the remarkable socialefficiency and the economic efficiency.