Study On Transient Characteristic And Parameter Of Large Hydro-Generator Based On Time-Stepping Finite Element Method

In order to study the transient characteristic and parameters of large hydro-generator, the Field-circuit Coupled Time-Stepping Finite Element Model is built for dynamic simulation of electric power system, in which the generator structure and the complicated non-liner factors are considered adequately. Based on this model, various operating conditions are simulated including open circuit and three-phase sudden short-circuit to study the response of power system. This model provides an theoretical principle for building the generator model for power system analysis. The main works are summarized as follows:1. In order to consider the influence of the generators'complicated non-liner factors on the generator-grid transient process, a two-pole Field-circuit Coupled Time-Stepping Finite Element Model of1000MW hydro-generator is built, in which the saturation of iron core, impedance of winding ends, distribution of stator windings and end rings of damper bars are taken into account. Furthermore, the rotor movement problem of unit generator is solved.2. Using the unit generator Field-circuit Coupled Time-Stepping Finite Element Model, the open-circuit of generator terminal ends as well as the stator three-phase sudden short circuit process are simulated. The no-load voltage curves, and the short-circuit current dynamic curves of stator windings and field winding are gotten. The correctness of the model is verified through the experiment.3. The variations of the synchronous saturation reactances under different operating conditions are calculated. The variation trends of direct-axis synchronous reactance and quadrature-axis synchronous reactance under different loads as well as different power factor conditions are presented.4. The steady state, transient, sub-transient reactance parameters and time constants of the generator are obtained through the analysis of phase A short-circuit current waveform curve. In addition, the dynamic reactance parameters of the hydro-generator are calculated by the impedance-frequency characteristic, in which the simulation model established above is used. Finally, the generator parameters calculated by the two methods are compared with the designed values.What have been done in this thesis can provide a theoretical foundation for structure design and dynamic characteristic research of the1000MW hydro-generator.