抄録
In recent years, squirrel-cage rotor induction generators are widely used as wind generators because of their cost, simple and robust rotor construction, and virtually reliable maintenance free operation. However, when they are injected to the utility grid, transient rush current, which amounts to several times as large as the rated machine current, and causes the voltage fluctuation in the power system. This transient voltage variation can not be disregarded especially in the case of large-scale wind machines from the view point of power system operation, because the electric power company has obligation to maintain the voltage within predetermined limit. Hence, it is necessary to estimate the value and duration of the voltage fluctuation for the company.
The voltage variation can be found by solving a set of simultaneous differential equations describing the dynamics of a wind turbine, a generator and power system. Since these equations usually contain linear and/or non-linear elements, it is difficult to solve them by using an analytical method, and so a numerical simulation is one of the most powerful method.
This paper proposes a new dynamic model to analyse electrical transient phenomena of a wind power generation system connected to the utility grid. And then, the over all system dynamics including linear and non-linear elements was simulated, and the voltage fluctuation was estimated. The simulation results showed that the voltage fluctuation in transient state was within the predetermined limit.
