Research On Temperature Control System Of Test Platform Of Evacuated Solar Collector Tubes

Solar thermal power generation is the main form of solar energy utilization,the trough thermal power generation has been in commercial application, linear fresnel type thermal power generation has been vigorously promoted. Solar vacuum tubes are photothermal conversion element, are the key components in solar thermal power generation. The performance of Solar vacuum tubes as the heat loss value directly affected the efficiency and cost of solar thermal power plant. Accurate temperature control system must be established to obtain accurate heat loss value. This is very important for the design of the line focusing solar heat collection. Taking the Evacuated solar tubes as the test object, according to the testing principle of the steady state equilibrium method, using PLC technology, OPC technology and self-tuning fuzzy PID control based on genetic algorithm, designs a temperature control system of heat loss value test platform of evacuated solar collector tubes.The controller is selected as the SIEMENS S7-300 PLC. Type selection and hard connection diagrams of main hardware equipment are introduced such as the PLC module, temperature sensor, temperature transmitter, power acquisition module, silicon controlled rectifier etc.Project development process of STEP7 is introduced. The hardware configuration and network configuration of each module of the system are completed. Programming Intelligent control algorithm using MATLAB, the communication between MATLAB and PLC is realized by using OPC technology. PC monitoring is designed by Kingview software, the parameters setting, temperature monitoring, data recording and other functions of the temperature control system are realized.The mathematical model of the control system is established by the experimental. On this basis, the control algorithm is studied. Comparing with the PID control, the self-tuning fuzzy PID controller is designed by combining the PID control with the fuzzy control. The traditional genetic algorithm is improved, the improved genetic algorithm is used to optimize the fuzzy rules of the controller.The control algorithm and the performance of the control system are verified by comparing the simulation experiment and the field test. The PID control algorithm, the self-tuning fuzzy PID control algorithm and the self-tuning fuzzy PID control algorithm based on genetic algorithm are simulated and compared. Experiment shows the self-tuning fuzzy PID control algorithm based on genetic algorithm is better than that of the other two algorithm. In the field test, the heat loss value of the evacuated solar collector tubes(4060 mm) is tested in the working temperature from 300 to 500?, the experimental data were analyzed and verified.Results show, the designed temperature control system has good stability and reliability. The self-tuning fuzzy PID control algorithm based on genetic algorithm is applied to the system can improve the accuracy of temperature control and test efficiency effectively, control accuracy is ± 1?, adjusting time is less than 35 min,meet the control requirements. The measured data of heat loss value by fitting, it's R-square is higher, them can reflect the situation of heat loss value of the evacuated solar collector tubes in various working temperature. The obtained experimental data also provide experimental parameters for the establishment of a solar concentrator system in China, it also provides reference data for measuring heat loss value standard.