October 28th, 2015

Confidence Interval for a Very Short Term Forecast in the case of an Hybrid Power Plant

The optimized management of a hybrid power plant (Genset + PV) implies an anticipation of sharp solar production variations. The use of images coming from a sky imager is the most efficient solution. Indeed, the processing of these pictures allows a fine prediction of the fluctuations risks.

The figure 1 shows for the 28th of October, forecasts produced ten minutes ahead. One can notice that the confidence intervals (for the percentiles from 10% to 90%) are developing all along the day.

They are quite narrow in the morning and afternoon, but in the middle of the day they are larger. This illustrate a very unstable cloudy situation. The consequence is at first a rapid production ramp up, followed by fluctuations developing during one hour.

The forecasts provide a comprehensive information to assess the risk and make the right decisions at the right time

Solar production nowcasting by sky imager

Figure 1: Actual (in blue) vs Forecast (in red/ orange for the percentiles) – 10 minutes ahead, Time step: 5 minutes