Construction And Performance Verification Of The Linear Heliostat Experiment Platform

Along with energy and environmental issues,various forms of new energy generation occupied more in the power grid.Solar energy is considered to be the most important renewable energy.According to different forms of energy conversion,the utilization of solar energy can be divided into two types:photovoltaic and photothermal,and the photothermal has a better application prospect in large and medium-sized power station due to its low cost,easy-to-grid.Among them,solar tower power technology is the most promising technology because of its highest peak efficiency and high concentration ratio.In the tower solar thermal power station,the heliostat reflects the sunlight to the heat sink located in the tower through two-axis tracking,improves the tracking accuracy of the heliostat,and measures the energy density on the heat absorber to optimize the heliostat field.In order to optimize the tracking and control of the mirror field,this topic has carried out practical research on tracking method and energy flow measurement by constructing a small heliostat that is easy to control and research.The main research contents are as follows:1)The tracking control system of heliostats is studied.The open-loop tracking system and closed-loop tracking system of heliostats are compared.The necessity of research on azimuth-pitch biaxial tracking heliostat open-loop tracking system is illustrated.Then,the model of the position of the sun and the moon,and the azimuth-elevation tracking formula with mirror eccentricity and six fixed geometric error parameters are introduced.2)Considering the experimental requirements for tracking correction and energy flow density measurement,a linear concentrating heliostat experimental platform was built.Considering the stability,ease of operation and expandability of the experimental platform,the structure of the control system is the upper computer,the middle layer,and the lower computer.Firstly,the main experimental equipment and the tracker's transmission were introduced.Then introduced the hardware structure and software design of the control system which is based on STM32,and finally creates the UI of the monitoring system.3)The tracking performance of the line concentrating heliostat is studied.An image acquisition system based on CCD(Charge Coupled Device)camera is built.The heliostat azimuth-pitch tracking formula with geometric error parameters is practiced and used.The tracking error of the heliostat is corrected.The tracking experiment method,the data processing method,and the tracking experiment process for improving the tracking accuracy of the heliostat are introduced in detail.The experimental data shows that the tracking correction method based on geometric error parameter model and the correction method of tracking the position of the tracking target can be used to improve the tracking accuracy of heliostat.4)The concentrating performance of the linear concentrating heliostat was studied,and the inverse ray tracing method was experimentally verified.The experiment was carried out on the Japanese and the moon,and the two simulations were simulated by the same simulation method.The experimental results show that there is a certain similarity between the moonlight spot and the sun spotlight,and provide data for the moonlight spotlight experiment of the tower power station.Support and theoretical guidance.5)Using the above tracking method and moonlight concentration experiment was carried out in the Yanqing Solar Tower Power Plant.Firstly,the control system and control method of the heliostat field of Yanqing PowerStation were introduced.Then the experimental platform with CCD camera photography system and illuminance array measurement system as the core was built,and the moon tracker was used to collect the moon information.The distribution characteristics of the light spot on the tower were obtained.Comparing the experimental results with the simulated mirror field efficiency,proves that the indirect measurement method of the concentrated solar flux distribution of the heliostat field of a tower power plant based on moonlight concentration has great feasibility and effectiveness.