大型柔性小孔式太阳能聚光器的优化设计与精度控制研究

Solar energy is clean, abundant and sustainable. However, the available solar radiation flux distribution on the Earth is 250W/m2. Low energy density rises the cost of solar power systems. Concentrating photovoltaics (CPV) is a major method to diminish its cost, since CPV use cheap concentrators to partially replace relatively expensive solar cells. It is difficult to manufacture and control large solar concentrators with high accuracy. A new method to develop large flexible parabolic solar concentrators will be proposed in this project. Through optimizing the patterns and size of holes on flexible mirrors to change its stiffness matrix and to bend the mirror to a parabola. The reduction mechanism of wind pressure by micro-holes structure will be studied. Dynamics of flexible multi-body system and dynamic focusing accuracy equations will be established, considering solar concentrators working environments with coupling multi-factors including gravity, thermal gradient, wind and kinematic errors of the solar tracking mechanism. On-line control system will be designed. The whole system will be validated through numerical simulation and laboratory fabrications. The concentrators have the potentials to be high energy efficient, light weight, and cost effective over the conventional methods, which make them have high commercial value and bankability.

太阳能是一种清洁和丰富的新能源，具有可持续性。因受天气、大气层、昼夜交替等环境因素的影响，地面上能够利用的太阳能平均仅为250 W/m2，低能流密度导致太阳能发电系统成本较高。降低发电成本的有效途径之一是采用聚光光伏系统，用价格相对低廉的聚光器部分代替太阳能电池以减少给定功率所需的电池面积。大尺寸和高精度的要求使聚光器加工控制技术难度大。本项目拟提出一种高效能大型柔性抛物面聚光器的新构型，采用弹性薄板镜体上小孔优化分布的方式，改变聚光器镜体刚度函数，使弹性镜体两端相对牵引形成抛物面。研究小孔结构泄风机理，同时考虑聚光器服役环境的多因素耦合特点，建立聚光器在重力场、温度场、风场等多因素耦合环境下的多柔体系统动力学模型和动态聚焦精度模型，设计在线控制系统，通过有限元数值优化和试验验证本构型的有效性。与传统方法相比，这种聚光器具有高效能、轻质和低成本等优点，具备较高的商业应用价值和可融资性。

基于有限元和薄壳弹性大变形理论，提出一种高精度大型柔性太阳能聚光器优化设计方法，包括槽式和碟式两种聚光器。结合理论推导、有限元数值优化和试验相结合的方法，建立大学弹性薄板-柔性索结构的聚光器力学模型，以最优聚焦精度为目标，通过有限元优化方法，获得最优构型。建立大型柔性聚光器机构的多体系统动力学模型和多场耦合作用下非线性动力学分析模型，通过数值模拟及仿真分析小孔直径和分布型式、柔性索张力等参数对聚光器动力学特性的影响。基于聚光器结构动力学模型，建立动态聚焦精度分析模型，分析热载荷、风载荷、自重、太阳追踪机构运动误差对聚光器动态聚焦精度的影响。通过研制的槽式和碟式聚光器原理样机，进行模拟环境试验、动力学及精度测试试验，验证理论方法的正确性和可行性，为大型柔性聚光器的工程应用提供基础性理论依据和技术支持。