Research On Optical Surface Shape Measurement Of Heliostat In Solar Tower Thermal Power Station

The solar tower thermal power generation system is one of the important ways of solar thermal power generation.The heliostat,as a key component of the solar tower thermal power plant,is mainly used to concentrate solar radiation onto the absorber to heat the heat transfer medium inside.However,the surface shape error of the heliostat has a significant impact on the optical efficiency of the mirror field,thereby affecting the power generation efficiency.Since the heliostat is usually composed of multiple reflective mirrors(submirrors),the angle error during the sub-mirror assembly has a significant influence on the overall optical surface shape of the heliostat.Therefore,the measurement and research of the surface shape error caused by the sub-mirror assembly of the heliostat is of great significance.Based on the above research background,this paper mainly proposes a method for detecting the inclination angle of the sub-mirror of the heliostat based on photogrammetry,and elaborates on the principle of the method and derives the theoretical formula in detail.The correctness and feasibility of this method are verified through experiments.The main research contents of this paper include:1.Investigating and summarizing the domestic and foreign research status of solar tower thermal power plants,analyzing the existing heliostat surface shape detection methods,and proposing a heliostat surface shape detection method based on photogrammetry.2.Analyzing and studying the sources of surface shape error of the heliostat,elaborating on the principle of photogrammetry,and respectively explaining the measurement principle and theoretical formula derivation for the proposed detection method.The principle analysis of Harris corner detection and FAST corner detection is conducted,and a Harris and FAST combined corner detection algorithm is proposed.3.Using MATLAB programming software,the proposed photogrammetric detection method is programmatically designed,and a heliostat surface shape detection software is developed,which has a graphical user interface,simple operation,and can conveniently and quickly calculate and display measurement results.4.Setting up an experimental platform,taking photos of sub-mirrors at different angles and distances,and conducting a large number of experiments with different experimental control groups to verify the correctness and feasibility of the measurement method.5.Conducting in-depth analysis of measurement errors,elaborating on the principle of distortion correction,analyzing and studying the influence of camera factors on measurement errors by calibrating the camera intrinsic parameters and correcting image distortion.The uncertainty error of corner point extraction was analyzed by repeatability measurement.