A wind turbine generator (WTG) system's output is not constant and fl uctuates depending on wind conditions. Fluctuating power causes frequency deviations and adverse effects to an isolated power system when large output power from WTG systems is penetrated in the power system. This paper presents an output power control methodology of a WTG for frequency control using a load power estimator. The load power is estimated by a disturbance observer, and the output power command of the WTG is determined according to the estimated load. Besides, the WTG can also be controlled during wind turbulence since the output power command is determined by considering wind conditions. The reduction of the power system frequency deviation by using the WTG can be achieved by the proposed method. The effectiveness of the proposed method is validated by numerical simulations. the output power control of the WTG is reduction of the frequency deviation. However, the focus of those reports is not directly on frequency control. In addition, for the effective utilization of the potential capability of the WTG, the strategy of the conventional output power smoothing is not a good provision. Therefore, there is need for achieving the power system frequency control by using the active output power control of the WTG. New control methodology for WTG for frequency control T. Kaneko et al.
408Under these circumstances, we are focusing on the frequency control of the small power system, and this paper presents an output power control methodology of the WTG for frequency control using a load power estimator. The load power is estimated by a disturbance observer, and the output power of the WTG is controlled by using the pitch angle control. The output power command for the WTG is determined according to the estimated load. In addition, wind speed condition is also considered, and thus, the proposed method ensures good control during wind turbulence. Moreover, the high-performance pitch angle control based on the output power command can be achieved by the generalized predictive control (GPC). The effectiveness of the GPC is shown in a previous work. 6 The reduction of the power system frequency deviation by the WTG can be achieved by using the proposed method. Simulation results by using an actual detailed model of the WTG show the effectiveness of the proposed method.This paper is organized as follows: in Section 2, the small power system model and the WTG model are given; in Section 3, a new control methodology of the WTG for frequency control is outlined; in Section 4, simulation results with the load power change and wind turbulence are explained to confi rm the effectiveness of the proposed method. Finally, the conclusion is drawn in Section 5.