Study of the errors influencing heliostats for calibration and control system design

Abstract

Power tower" or central receivers are a type of solar thermal energy system in which many heliostats, or movable planar mirrors, are used to focus sunlight onto a central receiver located on top of a tower. To design a control and calibration system for power tower systems, a thorough understanding of the numerous errors which can be present is essential. In this work, the various and different types of errors that present themselves in heliostat based solar energy systems are identified, categorized and assessed based on their potential impact and level of difficulty of resolution. The results of this work can be used to aid in designing a control system for heliostats in which the greatest amount of error can be corrected with the least difficulty.

Novel ANFIS Based Control for Solar Energy Heliostats

“…Introduction. A comprehensive error and control system study was earlier conducted by Freeman, Kiranlal and Rajasree [4], which provided a foundation for the type of control system required to obtain the needed accuracy and meet the necessary technical specifications for a concentrating solar thermal system. Three main configurations of tracking and calibration controllers' solar tracking were identified.…”

“…As with all control systems, there will be some error. The question is whether the error with an ANFIS control system is small enough to use for solar energy tracking, where accuracies of 0.01 degrees are needed [4].…”

An open-loop control algorithm for improved tracking in a heliostat

“…Furthermore, a detailed study conducted by Freeman and others, focused on the errors affecting the design of calibration and control systems, assessed the impacts of individual errors. Errors with a strong impact include those in sensors and actuators, as well as installation errors, highlighting the importance of carefully considering these factors in the design of calibration systems to mitigate their impact and optimize the performance of the heliostat system (Freeman et al, 2014).…”

A method for calibrating a single facet small heliostat based on extracting invariant moments

“…Large quantities of small single-facet (∼2.2 m 2 ) had been achieved by individual heliostats controller. Different types of errors were presented in Freeman et al [8]. The difficulty level of resolution was identified in heliostat based on solar energy systems.…”