Research On Stability And Control System Of Ac-Excited Generator

The stability of AC-excited generator is studied on the detail analysis of the math equation and basic characteristic of it. The law of static state stability at any speed is obtained. The"power-frequency transient characteristic"of the AC-excited generator is extracted. A simulation platform based on MATLAB/SIMULINK is established, which the vector control strategy is adopted. The simulation of AC-excited machine applied in pumped-storage hydraulic power plant is finished. The AC-excited experimental system is set up. Experiment is finished to test the conclusions. The main outcome of this dissertation is showed as follows:The mathematic model of the AC-exited machine is deduced. The basic theory and characteristic of it is analyzed.By the theoretical analysis, simulation and experimental research on the static state stability of the AC-excited generator, a conclusion has been drawn. If there is no automatic excitation regulator, the static state stability limit of the AC-excited generator descends with the descendent of speed. If the automatic excitation regulator is taken into account, the transient electric potential of the generator E ' remains invariant. The AC-excited generator remains the same static state stability at arbitrary slip point. So long as the operating point power is no lager than the static state stability limit Pm ax = E'Us X's, the system remains stable.By the theoretical analysis and experimental research on the transient state stability of the AC-excited generator, its"power- frequency transient characteristic"is put forward. By this characteristic, when the AC-excited generator is running at the transient process, the rotor accelerates and the input mechanical power debases. Considering the"flywheel effect"at the same time, the unbalanced transient power of the AC-excited generator is reduced greatly. So the AC-excited generator possesses higher transient state stability than the synchronous generator.The simulation platform base on MATLAB/SIMULINK of AC-excited system is established, which adopts vector control strategy. Through various simulations, it can be proved that the active and reactive power can be controlled independently, and the frequency of power system can be adjusted by AC-excited machine when it applied in pumped-storage hydraulic power plant as a motor.A dual-PWM variable-speed constant-frequency system based on DSP TMS320F2812 is set up. The experiments of speed regulating, static state stability and"power-frequency transient characteristic"have been done to test the former conclusion.