基于作物最佳光合效率下光伏温室系统“源-储-荷”协同机理与调控研究

This project is proposing an off-grid photovoltaic greenhouse system (PVGS) with lighting device, water pump system, irrigation equipment, cooling facilities, heating pump system and storage battery powered by photovoltaic modules on the roof of greenhouse, since the PVGS is the distributed form of photovoltaic power station of targeted poverty alleviation and it can realize the efficient combination of photovoltaic utilization and agricultural facilities. The project will carry out the research of cooperation mechanism and coordinated control of PVGS based on the optimum photosynthetic efficiency of crops. At First, the solar radiance and temperature distribution of greenhouse inside is calculated by the model with the different layout of solar cells modules, at the same time the model of photosynthetic efficiency of the crops under the different conditions of the environment of the greenhouse is deduced by the mathematic models of multiple regression and artificial intelligence. According to the models deduced above, the coordinate mechanism of the optimal photosynthetic efficiency of crops and photovoltaic maximum power point tracking (MPPT) is present under the optimized distribution of solar modules on the roof of the greenhouse. Second, the flexible coupling system models of PVGS are proposed by analyzing the influence from loads of demand side in the time and space, which is deduced according to the conditions of the optimum photosynthetic efficiency of the crops in the greenhouse. In addition, the energy capacity ratio between the energy storage and the crops demands of realizing optimum photosynthetic efficiency during the different growth period is considered. Therefore, based on the conditions of the optimum photosynthetic efficiency of the crops, this project proposes the models that how to meet the demands of energy coordinate and management among the greenhouse system of photovoltaic modules and energy storage and loads. At last, the quality and quantity of the crops in the PVGS are contrast with the same conditions of the greenhouse without photovoltaic system, and then the growth law of crops in different period is revealed in study of coordinate rules of PVGS, in order to understand the mechanism of energy supply and utilization better for the crops of PVGS. The research provides the theoretical foundation for high-efficiency facility agriculture combined with solar energy utilization, which is in accordance with the plan of China’s targeted poverty alleviation and new energy development.

光伏温室大棚作为光伏扶贫电站的分布式形式，可实现光伏利用与农业设施的高效结合，符合我国精准扶贫发展规划。本项目以独立光伏温室为研究对象，开展光伏组件布局对温室环境因子影响，探究环境因子为变量下作物叶片光合生理特性，提出温室作物最佳光合效率相适应的光伏组件布局及最大输出功率耦合模型与调控方法；深入分析温室负荷响应机理，研究引入需求侧响应对光伏系统输出功率波动的影响规律，构建基于作物最佳光合效率条件下光伏系统功率输出与负荷响应在时间尺度与空间尺度的耦合模型；研究设施作物在不同生长时期最佳光合效率所需能量与储能系统容量配比，实现基于温室作物最佳光合效率调控下的系统“源-储-荷”协调控制与能量管理。通过对所选择作物产量及果实品质展开研究，揭示系统能量调控耦合机制对作物不同生长阶段的作用规律，获得与生长条件相适应的用能与供能机理。项目的完成为太阳能光伏与农业设施的高效结合提供理论基础。

本项目以离网光伏温室为研究对象，以实现温室作物草莓叶片最佳光合效率为目标，开展了光伏发电系统，温室负载需求以及蓄电池储能系统三者之间的协同与耦合调控研究。通过将系统能量与设施作物对环境因子最优需求进行耦合，提高了离网光伏温室系统能量利用率以及温室作物的品质。具体研究内容包括：1）光伏组件布局对温室内辐照度，温度场随时间尺度及空间尺度变化，获得光伏组件影响下的温室作物最佳点和光饱和点的光合有效辐射，分析温室环境因子对光伏组件输出特性，为离网发电光伏系统最大功率与平抑波动协同调控提供理论基础。2）基于作物最佳光合效率的负载耦合调控策略，通过引入需求侧响应研究光伏发电系统功率输出与负荷在时间尺度和作物需求的耦合特性；3）研究作物最佳生长条件下所需能量与储能系统容量配比，实现基于温室作物最佳光合效率调控下的系统“源-储-荷”协调控制，获得能量调控对作物品质特性的影响规律。本项目的理论成果包括：1）提出改进的二极管模型，实现在线测量光伏组件的电流电压特性，预测和在线诊断发电系统光伏组件电特性参数和最大输出功率；2）提出一种新的测量光伏组件表面温度不均匀而导致的输出功率损失的数学模型和测量方法，该方法根据组件出厂特性参数并且通过测量表面温度分布，估算光伏组件在运行状态下的“热-电”功率损耗；3）提出适用于光伏组件铺设于屋顶的温室内光合有效辐射模型，该模型考虑了入射光谱波长和光伏电池材料透射光谱，根据普朗克黑体辐射定律推导得到室内光合有效辐射分布，通过实验验证了模型的有效性；4）设计协同蓄电池荷电状态与母线电压稳定的光伏系统最大功率点跟踪的控制策略，采用扰动观察协同积分分离式控制方式，通过制备样机实现离网光伏发电系统“源-储”协同调控；5）构建光伏阵列最佳工作点处的阻抗模型，采用阻抗变换器进行脉宽调制，实现负载与光伏发电等效阻抗协同调控。本项目的成果将为提升光伏温室系统效率以及光伏农业广泛应用提供理论与技术基础。