Evaluation of forecast accuracy of aggregated photovoltaic power generation by unit commitment

An electric power system containing high penetration photovoltaic power generation system (PVS) should employ a highly accurate day-ahead forecast method of aggregated power output of PVS in the generation scheduling so as to realize the economic load dispatching. Considering the load-following capability of utility generators, however, small forecast error is not so influential, while large forecast error should be avoided. By using a simplified unit commitment model, this study evaluates the forecast accuracy of aggregated PVS power output by means of the amount of shortage or surplus of power supply in the electric power system. As a result, the shortage occurs occasionally, requiring the increase in the operating reserve. The surplus occasionally occurs in spring even without the forecast error. Avoiding the large forecast error contributes to the decrease in the operating-reserve of utility generators as well as the suppressed PVS power output, even though the average forecast accuracy is not improved so much.