The authors have been making a study of an independent source system utilizing wind turbine generator in recent years. This system is composed of four main installations, that is, a wind turbine generator, a diesel engine generator, an electric water heater (or an electric power storage flywheel), and an alternating power control device. The strong points of this system is that it is possible to increase generating electric power, because the brushless three-phase synchronous induction generator with two stators and without exciter developed by authors is used as the wind turbine generator of this system. We have reported about the experimental results of electric power characteristics in steady state by using the simulated device of the proposed system up to now. In this experiment, the terminal voltage and the current of the proposed independent source system did not change and the quality of electric power was good when the wind turbine generator operates as a synchronous generator and also as an induction generator. In this paper, the experimental results of electric power characteristics in transient state of the simulated device are reported. In this experiment, the change of the terminal voltage and the current are extremely small and the electric power characteristics are very good while the operation of the wind turbine generator changes from synchronous generator driving to induction generator one and also in the opposite operation. The electric power characteristics of this simulated device in both steady and transient states are good; therefore this proposed system would be put to practical use.