Analysis And Calculation Of Transiant Temperature Rise For Transformer Winding

With the development of the economy,the power grid is increasing rapidly.But the construction of the power grid lag causing the power transformer usually needs work in the overload situation.The transient temperature rise of the power transformer insulation system is the key factor for load capacity.The change of the transformer hot spot temperature directly influenced the insulation heating aging and use ratio.To prolong the use aging of the transformer and increase the economy benefit of the operation,it is important to confirm the winding transient temperature accurately in varied load and environment temperature.A two-dimensional model of the oil-immersed power transformer is established by using the special finite software MF2 D.The distribution of winding leakage magnetic field and eddy current loss is analyzed,which provides the basis for the calculation of the winding transient temperature rise.On the basis of the analytical formulation in the GB/T 1094.7-2008 loading guide for oil-immersed power transformers,the calculation programmer of the winding transient temperature and the aging loss is written by fortran language.On the basis of winding loss and hot convection rule,and combining the knowledge of the transformer construction structure and hot and cooling process,the influencing factor of the time constant and hot spot factor is stated.A typical transformer product is calculated and analyzed by analytical method.The time constant and hot spot factor is analyzed.On the basis of it,the winding hot spot temperature changing with time in rated load,overload and periodic load is researched.In the end,the steady and transient hot model is established by the finite volume software Fluent.The winding hot spot temperature rise influenced by inlet temperature,inlet velocity and different load is calculated and researched.The temperature change which influences the input hot source is considered.The temperature field in different time and hot spot temperature which changes with time is obtained.The rationality steady model is verified by comparing with the measured value.Then the rationality of the two method is verified with each other by comparing the results of the analytical method with numerical method.