Manufacture Of Group Control System Of The Heliostat Field For Solar Tower Power Plant

Solar power tower plant generate solar power by using mirrors or lenses to concentrate a large area of sunlight onto a receiver to convert the concentrated light to solar thermal energy,which drives a heat engine connected to an electrical power generator.It has a large-scale cost advantage and is the key development direction of new energy utilization in the future.The heliostat field is a key subsystem for tracking light in concentrated solar power system,which directly affects the performance of power generation,and the cost accounts for about 40% of the total cost of power plant.To meet the needs of efficient and low-cost solar tracking in solar power tower systems,our research group proposed a group control tracking method and designed a large heliostat structure that can realize group tracking of heliostat units.This type of heliostat is coupled with the sun’s altitude and azimuth in the horizontal coordinate system,as well as the declination and right ascension in the equatorial coordinate system,and it has complicated tracking laws.To ensure the precise linkage between the mirror unit array and the heliostat array,high synchronization should be maintained between the servo drives of the mirror field.Aiming at the above-mentioned tracking control difficulties,this paper studies the group control tracking strategy of heliostats and develops a real-time drive controller based on Ether CAT bus to achieve high-performance solar tracking focusing on heliostat fields.In this paper,based on the planetary VSOP87 zodiac parameters,the astronomical theory and SPA algorithm related to the calculation of the position of the sun,a specific method for calculating the apparent trajectory of the sun is given.The method was used to simulate the data of solar right ascension,apparent declination and time difference in a specified time period,and the calculated data and observation data were compared.The results prove that the algorithm has high accuracy and can fully meet the needs of the heliostat’s light gathering accuracy.This paper analyzes the structure,driving characteristics and focusing principle of the group-controlled platform,and establishes the motion coordinate system of the device.According to the relationship between the motion coordinate system of the device and the elements of the horizontal rectangular coordinate system,the coordinate transformation matrix is obtained,and the calculation model of the tracking device is established.An open-loop tracking strategy for group-controlled tracking platform is proposed.This paper calculates the two-axis angle of the tracking platform under the control of the open-loop tracking strategy at various times on a given date.By comparing the calculated angle value with the ideal angle value,it is determined that the open-loop tracking accuracy can meet the needs.A light barrel sensor scheme based on a four-quadrant silicon photovoltaic cell is proposed,the sensor structure design is completed and a closed-loop control strategy is formulated.This paper proposes a control system based on the Ether CAT bus,and completes the design of the slave station information interface,synchronization mode,process data communication,and tracking platform application layer software.The data content of the bus transmission is planned,and the preparation of the heliostat control program of the master station is completed.The chip schematic diagram is drawn and PCB wiring is performed,and a sample circuit board is processed according to the selected chip.Experimental research on the bus performance of the control system and the tracking accuracy of the heliostat platform was carried out.According to the overall experimental plan,the bus performance test and heliostat tracking accuracy test experimental platform were built,and the real-time test and platform closed-loop tracking accuracy test were completed.The results show that the precision of the group-controlled heliostat tracking platform equipped with the principle prototype can reach within 0.2 °,which can meet the tracking accuracy requirements of tower power stations.The average communication delay of the bus communication between the mirror group controller and the heliostat controller is 4 μs,and the real-time performance can meet the communication requirements of the heliostat field.