A new wind turbine simulation tool for a time-domain dynamic simulation was developed in this study. The tool consists of models of aerodynamics, drive train, generator, actuators, and controllers for pitch and yaw controls. For the wind turbine model, the NREL 5MW reference wind turbine was used. Using measured data, the developed tool was applied to predict annual energy production from the wind turbine at four different sites in a complex terrain of Korea. The results were compared with those predicted by a commercial frequency-domain program widely used to predict the annual energy production from a wind turbine. Without a yaw control, the predictions from the proposed tool were close to those from the commercial wind farm design program. Also, from simulations with and without yaw controls, the differences in power predictions were quantified. The results of this study suggest that the power production from a wind turbine can be predicted by the proposed time-domain wind turbine simulation tool with a proper yaw algorithm which is not available in commercial frequency-domain programs. Further research is needed to experimentally validate the simulation results with yaw algorithm