| Energy shortage and environmental pollution are major problems facing the world today.As the main force of clean energy,solar energy has many advantages,such as no pollution and huge energy.Therefore,it is of great significance to improve the utilization rate of solar energy.Photovoltaic/thermal comprehensive utilization(PV/T)technology is currently a hot research topic.This technology can not only obtain electric energy but also thermal energy,and reduce the temperature of photovoltaic cells while collecting heat,improve power generation efficiency and make great use of solar energy.In this paper,the flat-plate water-cooled PV/T system is studied.The mathematical model of the total equivalent power output of the system is established.By designing an optimal control strategy,the total equivalent power output of the system is relatively maximum.Firstly,the hardware platform and monitoring system of photovoltaic/thermal comprehensive utilization system are built.The hardware platform includes photovoltaic power generation system and heat collection system.The main equipment include generator set,solar heat collector,water pump and heat collection water tank.The monitoring system is designed based on Lab VIEW software platform.It can receive various data from the lower computer,monitor the status of the system in real time,and send instructions to realize control.Secondly,photovoltaic cell power generation efficiency is closely related to PV/T module temperature.Accurate and real-time prediction of PV/T module is of great significance.In this paper,by analyzing various factors affecting PV/T module temperature and combining the data collected by the experimental platform,the PV/T module temperature prediction model based on support vector regression algorithm is established.Experimental results verify that the model has high prediction accuracy and strong generalization performance,and its prediction value can be regarded as the real value of PV/T module photovoltaic cell temperature at this time.Then,by analyzing the electric and thermal power obtained by the system and the power consumed by the system in operation,a mathematical model of PV/T system output total equivalent power is established.Quantum genetic algorithm is used to optimize the extreme value of the constrained multivariate nonlinear objective function,and the optimal values of PV/T module temperature and water pump frequency are obtained when the system obtains the maximum total power.Finally,according to the characteristics of PV/T module such as large temperature inertia,delay,nonlinearity and time variation,dynamic matrix control(DMC)and PID control cascade control strategy are adopted to optimize the PV/T system.DMC-PID cascade gives full play to DMC’s advantages of strong inertia,delay adaptability and PID anti-jamming capability.The simulation results show that the control system has strong robustness and good regulation performance,and can stably control the temperature of PV/T modules. |
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