Finite Element Calculation Of Electromagnetic Parameters Of 2000MW Level Four Poles Nuclear Turbo-generator

Because of nuclear power is not using conventional fossil fuel,having larger total energy,less emission and high energy density,possessing the advantages of generating electricity stably and continuously,it has become the key to solve the energy problem.It is particularly important to design the nuclear turbo-generator,and the calculation of electromagnetic parameters is also an important link in the design process.In this paper,according to the structure parameters of an certain machine in development of 2000 MW level four poles nuclear turbo-generator's blue print,two kinds of models of the generator was established respectively in Ansoft/Maxwell 2D magnetostatic and transient field,based on the excitation current calculation principles of magnetostatic field and transient field-circuit coupling field,obtaining the no-load and load excitation current and the distribution of magnetic field of the generator,and the essences of the difference between two kinds of methods were analyzed.Based on the above-mentioned models,the excitation current of 600 MW and 1100 MW level generators in the actual operation were calculated again,the results were compared with the actual test values,and the correctness of the finite element method was proved which used in the paper.Further analysis of the causes of error between the finite element method and measured values,the corresponding solutions are putted forward to reduce the finite element calculation.Finally,Newton iteration method was applied in the finite element calculation of excitation current,and the convergence of iterative calculation of excitation current with finite element method was improved,which also laid a foundation for the interface program design in the fourth chapter.On the basis of load excitation current calculation with finite element method,according to the park transformation of turbo-generator,the generator's stator inductance were decomposed by dq0,the synchronous reactance of saturated values of the machine were obtained.Analysis of the relationship between the skin effect of turbo-generator's damper system and the slip frequency,a model of d/q axes reactance calculation with frequency domain method was built,calculation of d/q axes reactance frequency characteristic curves of field winding in the state of short circuit and different damper systems,it is concluded that the influences of different damper systems on d/q axes reactance.The physical essences of equivalent damper windings with calculation of transient reactance and sub-transient were reveled,and the transient reactance and sub-transient reactance of d/q axes was calculated.Based on the structure characteristics of turbo-generator and the principle of electromagnetic parameters calculation,the universal software that Excel VBA drives Maxwell to calculate electromagnetic parameters of turbo-generator is designed,The software makes the excitation current can automatically iterative calculate and achieves the goal of self-optimizing,the difficulty of excitation current calculation was reduced immensely,and it has the functions of building model parametrically and solving electromagnetic parameter of generator with one key.Nor can the interface program that designed in this paper be applicable to all turbine generators in the field of electromagnetic parameters calculation,but also analyze the influences of the structure of stator and rotor on magnetic field in the generators and electromagnetic parameters conveniently.The software can shorten the development cycle of turbo-generator and has strong practical engineering application value.