Study Of Field Current Calculation Methods Of Large Capacibility Turbine Generators

In the design process of turbine generator, excitation current calculation is a important issue. Since the exist calculation method can not adapt to the excitation current calculation of 1000 MW class nuclear generators with special structures, such as partial offset rotor slots, partial shallow slots and stator axial ventilation holes, it is an urgent problem to widen the calculation applicability.By the study of the relationship between key factors and the excitation current, new methods of excitation current calculation with wide applicability have been presented. These methods are based on motor theory, motor design theory, electromagnetic field theory and computer program design method. This research includes study of calculation formula, data collections of turbine generator schemes, analysis of calculation accuracy and speed. The main research results are:(1)The excitation current calculation method of fusion formula has been established. The algorithm contains various analysis, such as magnetic density analysis of generator air gap, leakage magnetic field analysis of stator and rotor slots, potier reactance analysis, current vector synthesis analysis of rated excitation current. Not only the basic method of motor design but also the actual design situations of Shanghai Electric corp., including generator models of 1000 MW nuclear power generator, has been taken into consideration.(2) Finite element analysis(FEA) excitation current calculation method has also been established, and excitation currents calculation results of generators with stator axial ventilation hole structure have been acquired. The calculation results and its relevant test show:(1)The fusion formula method are suitable for 300 MW, 600 MW, fossil 1000 MW and nuclear 1000 MW water-hydrogen cooled turbo-generator, and the calculation accuracy is within 10%.(2) FEA calculation method is also applicable to those generators, and the calculation accuracy is within 5%, which meets the accuracy requirement of Engineering calculation.(3)Both calculation methods widen the calculation applicability.(4) The computation time of FEA calculation method is less then that of imported programs.The innovation of this paper lies in:(1) New methods of generator excitation current calculation, which widen the calculation applicability, has been established.(2) High speed and accuracy has been acquired through combination of the fusion formula calculation method and FEA algorithm.(3) The automation of the whole calculation process has been realized by using the VB programming tools of MICROSOFT EXCEL and FEA software ANSYS.