Solar Thermal Collector System Modeling And Control Strategy Research

As the rising oil prices and the worsening global climate, the development and utilization of solar energy has been paid more attention. In the national12th Five-year Plan, Concentrating Solar Thermal Power (CSP) technology would be supported and promoted vigorously. Due to high temperature and concentration, solar power tower is the most economical form among CSP. However, the relative researches in the CSP field started late in China, there still are many important problems to solve. This thesis mainly focuses on the researches of sun motion, heliostat tracking, Beam Characterization System (BCS) and optimized control strategy of heliostat field, and makes some explorations as follows.First, the sun motion model is established to calculate the sun angles throughout a whole day. Variation rule of the sun angles is summarized.Second, an ideal two-axis heliostat model which is a three-dimensional motion system is built to achieve sun-tracking and a heliostat tracking algorithm is proposed. Based on simulation and experiments, the disciplines between heliostat angles and receiver position are concluded.Third, a geometric imaging model of heliostat reflection is put forward to overcome low accuracy of open-loop control, and BCS is established to raise tracking accuracy. Based on nonlinear least squares an optimized method is proposed to achieve parameters estimation in order to build a new model.Forth, this thesis researches on the correlation among control period, the heliostat geometric position and the solar facula position formed by reflected rays projected on the aim point of the central receiver. Through simulation experiments, the control strategy named partitioned minimum-period is presented and applied to optimize the heliostat field layout.This thesis presents the heliostat tracking model, tracking control algorithm, BCS and optimized control strategy for heliostat field. These methods are confirmed to be feasible and high precision through simulations and experiments. Also, the high-precision sun tracking and low spillage of the solar facula are achieved and the conclusion of the thesis lays a theoretical basis for CSP technology.