Intra-day global horizontal irradiance forecast using FY-4A clear sky index

Abstract

Accurate forecasting of Global horizontal irradiance (GHI) plays an irreplaceable role in power system expansion, power generation production scheduling, maintenance scheduling and ensuring continuous power supply. A method for GHI forecasting based on FY-4A satellite images is proposed, called FY-4A-Heliosat. This method is derived from the clear sky model (MCclear) and the future clear sky index (CSI), which is obtained by comparing the continuous cloud albedo (CAL) maps derived from AGRI satellite images according to Heliosat-2 method. The forecast horizon is 30 min to 3 h with a 30-min horizon resolution. The combination of climatology and persistence model (CP) is chosen as reference forecasts. Under all sky conditions, the results show that compared with CP model, FY-4A-Heliosat model is better in most cases and seasons. The FY-4A-Heliosat method underestimates the GHI in four seasons for all time horizons. Annual studies indicate that the FY-4A-Heliosat method performs better than the CP method for all forecast horizons; the nRMSE is 17% to 25% for the annual performance. Forecasts with change in cloud conditions show that: the FY-4A-Heliosat method performs better than the CP method in clear, partially cloudy, overcast and clear-to-cloudy conditions. For the cloudy-to-clear set, the FY-4A-Heliosat method needs to be improved future. The results demonstrate that the proposed method is suitable for very short term GHI forecasting.