A PV system's power output is not stable and fluctuates depending on weather conditions. Using a battery is one feasible measure to stabilize a PV system's power Output, but it requires additional costs and results in additional waste of used batteries. In this paper, we propose a new measure for smoothing the short-term change in a PV system's power output, which is performed by tuning the characteristics of Maxinium Power Point Tracking (MPPT) control without additional equipment. In our proposed measure, when the insolation increases rapidly, the operation point of MPPT control changes to a new point where the maximum power is not generated with the current insolation, so that the rate of increase in the PV system's power output is limited to a certain value. In order to evaluate the effect of the proposed measure on the operation of electric power systems, we evaluated the required capacity of generators for load-Frequency control (LFC). It was revealed that the additional LFC capacity is not required even in the case where penetration of PV systems reaches 5% of the utility system's total capacity if the proposed measure is applied to all PV systems. (c) 2005 Wiley Periodicals, Inc.
