Research On The Stability For Huge Hydro-generator Based On Time-stepping Finite Element Method

1000MW huge hydro-generator is the inevitable development trend of hydro-generator for utilization of water resources, but, 1000MW huge hydro-generator, which not yet put into operation in the country and the world, is still in researching and planning stage. It is very necessary to research the technical issues for 1000MW hydro-generator. In this paper, the field-circuit coupling model based on the time stepping finite element method (T-S FEM) is established, and the static stability and transient stability of 1000MW hydro-generator is calculated and analyzed, when it is working with power grid connected.First of all, research methods for the stability of power system and generator are reviewed, and the application status of finite element method (FEM) in the aspect of motor and generator operation performance analysis is summarized. In this paper, the deficiencies of traditional methods are pointed out, and, it is proposed simultaneously that the field-circuit coupling model based on T-S FEM is the best method for the research of the stability for 1000MW huge hydro-generator.Secondly, based on the design data of 1000MW hydro-generator that is in construction planning, two-dimensional finite element model without considering the end effect is established. The field-circuit coupling model of 1000MW hydro-generator is formed by connecting the finite element model of generator and the infinite power grid through a booster transformer and transmission line.Then, using the field-circuit coupling model, the electrical angular velocity curve response to the small disturbance is obtained, which is coursed by 0.1 p.u. sudden increase of input power. The eigenvalue of oscillation mode for electrical angular velocity curve can be obtained from the results of prony analysis, and then, the limit of static stability power and static stability power angle can be summarized by observing the variation law of dominant eigenvalue.Finally, using time-domain simulation method, whether the short-circuit faults locate at the generator terminal or the end of transmission line, the transient stability of 1000MW hydro-generator is calculated and analyzed based on the field-circuit coupling model. Short-circuit fault must be cleared immediately in order that the power system and generator can maintain stable operation, in this paper, fault clearing time limit under different conditions is obtained by mass of simulation.The results obtained in this paper can provide valuable reference for the actual operation of 1000MW hydro-generator, and it is also useful and valuable for the design of protection devices, the dispatching of power grid and the debugging of generator when be connected to power grid.