| The three-phase induction generator is characterized with simple construction, operating reliability, and good dynamic performance. It represents the development tendency of the power generation block in isolated power systems. To understand the variables in different circumstances and provide the foundation for machine design, the dynamic operation performances under voltage building and load sudden change for the induction generator are studied in the paper.The parameters of the machine are measured by no-load test and short-circuit test. The relationship between the exciting current and corresponding air-gap voltage at the rated frequency is obtained, thus determining expressions for exciting inductance and exciting current in linear segment form. The equivalent circuits in a/30 reference frame are based on the parameters by above tests.Simulation and analysis are performed to its dynamic process. By applying the stationary aβ0 reference system to the induction generator, a set of differential equations based on basic electromagnetic laws is established. With consideration of the magnetizing inductance influenced by the magnetizing currents, the varying-coefficient differential equations are solved by the numerical method. The calculated results show that the buildup voltage is increased and transient process is decreased with the increase of capacitance. The simulation results are in good agreement with the experimental results, which verify the correctness of the presented method.Dynamic performances during sudden changes in load are analyzed and simulated. It emphasizes on the processes of three-phase sudden short circuit in machine's terminal and self-excitation capacitor switching off. The effect of the instant at which the induction generator is short circuited on the maximum current is showed. The comparison between the simulation results and experimental results is made and the validity of the simulation methods is confirmed. |
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