Error Assessment of Solar Irradiance Forecasts and AC Power from Energy Conversion Model in Grid-Connected Photovoltaic Systems

Energies

Gianfranco Chicco¹  Valeria Cocina¹  Paolo Di Leo¹  Filippo Spertino¹  Alessandro Massi Pavan² 

[1] Energy Department, Politecnico di Torino, corso Duca degli Abruzzi 24, Torino 10129, Italy;Department of Engineering and Architecture, University of Trieste, Via Valerio 10, Trieste 34127, Italy;

关键词: photovoltaic systems;    weather forecasts;    photovoltaic (PV) conversion model;    power profiles;    error assessment;    distributed generation;    renewable energy;    irradiance spike;   

DOI  :  10.3390/en9010008

来源: mdpi

【 摘 要 】

Availability of effective estimation of the power profiles of photovoltaic systems is essential for studying how to increase the share of intermittent renewable sources in the electricity mix of many countries. For this purpose, weather forecasts, together with historical data of the meteorological quantities, provide fundamental information. The weak point of the forecasts depends on variable sky conditions, when the clouds successively cover and uncover the solar disc. This causes remarkable positive and negative variations in the irradiance pattern measured at the photovoltaic (PV) site location. This paper starts from 1 to 3 days-ahead solar irradiance forecasts available during one year, with a few points for each day. These forecasts are interpolated to obtain more irradiance estimations per day. The estimated irradiance data are used to classify the sky conditions into clear, variable or cloudy. The results are compared with the outcomes of the same classification carried out with the irradiance measured in meteorological stations at two real PV sites. The occurrence of irradiance spikes in “broken cloud” conditions is identified and discussed. From the measured irradiance, the Alternating Current (AC) power injected into the grid at two PV sites is estimated by using a PV energy conversion model. The AC power errors resulting from the PV model with respect to on-site AC power measurements are shown and discussed.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.