Research On Matching Optimization Of The Load-source In The Stand-alone Photovoltaic Greenhouse System

At present,with the progress of social economy,culture and other aspects,people’s yearning for and pursuit of material life is also increasingly strong,China’s facility agriculture ushered in a new stage of development.Greenhouse as its main representative,can carry on the agricultural production under the special environment,can adjust the greenhouse environment at will to meet the needs of different growth stages of crops.By combining stand-alone photovoltaic power generation technology with greenhouse,photovoltaic modules are laid on the roof of the greenhouse,which can provide electricity for the greenhouse load while shading to meet the light demand of crops.However,due to the mismatch between the load power of the stand-alone photovoltaic greenhouse power generation system and the photovoltaic output,the actual power generation of the photovoltaic system has not been fully utilized.Therefore,it is of great significance to study the charge-source matching of the stand-alone photovoltaic greenhouse system for the planning and construction of the system.In this paper,based on the optimal photosynthetic efficiency of crops and greenhouse environmental field,the coupling between power output and load response of the photovoltaic system was established to realize the system load-source optimization.（1）The output characteristics of the independent photovoltaic greenhouse system were obtained by modeling and simulation analysis of the photovoltaic modules according to the five-parameter method.The power generation of the photovoltaic system is calculated and experimentally analyzed,the results show that the photovoltaic output of the stand-alone photovoltaic greenhouse system is not ideal.The influence of multi-factor combination on the output characteristics of the modules is analyzed through experiments,the experiment shows that the environmental factors in the greenhouse will reduce the output power of photovoltaic modules,but the outdoor environment has a greater impact on the output of the system.In order to improve the efficiency of double-sided modules,corresponding measures should be taken.（2）The numerical model of indoor irradiance and temperature field in photovoltaic greenhouse was built,and the simulation and experimental analysis were carried out.The results show that the total relative error range of irradiance field is0.2%-15%.The temperature field simulation results show that the relative error between the simulation and the experiment temperature of the vertical facade of the greenhouse center and the ground is less than that of the horizontal plane,and the simulation results of the temperature difference are consistent with the experimental results.（3）The correlation between photosynthetic rate and environmental factors was studied and analyzed.Through the influence mechanism and experimental analysis,the results showed that the temperature over 35℃had a negative effect on the photosynthesis of‘Jingzangxiang’strawberry,and the photosynthetic effective radiation was in the range of 360-470μmol·m^-2·s^-1,which was suitable for the growth of strawberry.The experimental results provide a theoretical basis for load regulation based on photosynthetic rate.A load control scheme was proposed based on the greenhouse indoor environment field and the environmental factors required for the optimal photosynthetic rate of strawberry.（4）Research on load-source matching optimization of stand-alone photovoltaic greenhouse system was carried out.the power consumption model of each load in the facility greenhouse is established,the optimization strategy of‘time shift’is proposed.The results of the optimization experiment show that the photovoltaic output of the stand-alone photovoltaic greenhouse system is also significantly improved compared with that before optimization,up by 24.9%in summer and 27.9%in winter,which proves the rationality of the optimization strategy.Based on the correlation between the optimal photosynthetic rate of strawberry and environmental factors,combined with the indoor temperature field and irradiance field model established in photovoltaic greenhouse,this paper proposes a load-source optimization strategy,which has certain reference value for the load-source matching of Stand-Alone photovoltaic greenhouse.