Intra-hour solar irradiance forecasting using ground-based sky imager

• Main Author: Zhang, Hongming
• Other Authors: Gooi Hoay Beng
• Format: Theses and Dissertations
• Language: English
• Published: 2017
• Subjects: DRNTU::Engineering::Electrical and electronic engineering
• Online Access: http://hdl.handle.net/10356/72609
• Institution: Nanyang Technological University

Solar intermittency is a critical issue which limits the development of grid-connected photovoltaic system in the applications of solar energy. High accuracy of solar irradiance forecasting plays an important role in establishing modern photovoltaic generation power system. With the prediction data provided, the system will take appropriate actions to control the energy storage system. This thesis focuses on one of the methods of short-term solar irradiance forecasting based on ground-based sky imager, i.e. sky images captured by Total Sky Imager (TSI) and Wide Angle High- Resolution Whole Sky Imaging System (WAHRSIS). The images obtained will be processed to determine the cloud cover and analyzed to estimate the cloud motion velocity by using the MPIV algorithm. The cloud condition of next few minutes will be predicted and consequently the solar irradiance values can be calculated based on the program developed in this project. The sample results taken in this project show that the program in this project can forecast the solar irradiance in specific location for about 5-15 minutes with mean prediction error about 20%. The intra-hour solar irradiance can be obtained by consecutively collecting images into the program. Depending on different locations and sky imager systems, the same algorithm can be applied accordingly by calibrating the threshold value for cloud determination and image resolution to forecast the solar irradiance.