Control algorithms and hardware for a concentrating solar plant based on fluidized bed with improved heliostat calibration system

The present paper deals on a concentrating solar system with thermal energy storage, recognized as a potentially useful technology to be integrated in power systems and industries, to support their decarbonization. The paper focuses on the control system of the solar field, employing two-axis (pitch-roll) tracking mirrors (heliostats) and a beam-down system. The paper presents two innovative aspects of the technology: an integral error correction algorithm to enhance pointing accuracy, and the use of an inclinometer for each heliostat, to increase system reliability. The system has been designed, implemented, and tested for more than 12,000 h on an industrial scale, then optimized on-site to maximize charging efficiency, obtaining encouraging results in terms of reliability and aiming accuracy, despite the use of rugged commercial components to keep costs low. The results of the experimental tests show a significant reduction of the aiming error, obtained through the proposed correction algorithm.