In order to reduce the fluctuation of wind power output, researches on installation of storage batteries to wind power generation have been conducted. But in order to efficiently perform the charge and discharge control of storage battery, accurate estimation of wind power is required. Generally, power curve, a characteristic curve of wind power output vs. wind speed, is used for the estimation. In our research, we propose a simple and high-precision modeling method (Just-In-Time Modeling). Finally, Just-In-Time Modeling is further proved to be a more effective method through computational simulations: short-term forecasts are also discussed.