Design Of Solar Tracking Device With The Parallel Mechanism

The solar photovoltaic（PV）power generation,as a new and clean energy,has been widely concerned and applied worldwide.With the rapid growth of new PV installed capacity in the world,how to improve the power generation efficiency of solar PV systems is an important and valuable research aspect.According to the existing research,if the automatic tracking device is adopted,the solar energy acceptance rate can be increased by about 35%and the power generation capacity can be increased by more than 20%compared with fixed PV power generation.However,the solar tracking device usually adopts the traditional series mechanism in practical application,which is greatly affected by the environment,and the load-carrying capacity and stability are poor.In order to address these issues,in this thesis,a new type of solar tracking device with parallel mechanism was proposed,and a complete solar tracking system was designed,which can be effectively adjusted and track the sun accurately.The main conclusions of the thesis are as follows:（1）Based on the theory of the celestial sphere,the position model of the sun in the horizon coordinate system was established.The range of azimuth and elevation angle in Hangzhou was obtained by the high precise Bourges declination angle algorithm,and the azimuth angle was corrected in zero line and calculated after revising the azimuth formula.Finally,the ideal tracking area for one year was solved.（2）A group of spatial 2R parallel mechanism was synthesized based on the opened single-chain analysis method.The U-PRU-PUS parallel mechanism was analyzed with the screw theory,which proved that this mechanism has 2R degree of freedom and is fully decoupled.The direct and inverse kinematics of the parallel mechanism were obtained by the space transformation matrix,and the singularity of the mechanism was analyzed by the Jacobian matrix.Then,the workspace of the parallel mechanism was solved with the boundary searching algorithm.After the transformation of the sun position angle and the Euler angle of the mechanism,the mechanism can reach[-90°,90°]in azimuth and[0°,90°]in elevation.（3）The adaptive genetic algorithm based on variable weighting coefficients was used to search the optimal solution of structure parameters in parallel mechanism.After analyzing the Pareto solution set,it can be concluded that the optimized tracking area S=12954.5,which was4.6%larger than that before optimization,and the optimized driving rod length l₃=372.2mm,which was 11.2%shorter than that before optimization.The optimized structure has more compact structure,lower energy consumption and larger tracking range.By comparing the ideal and actual sun position obtained from the kinematic model of the parallel mechanism,it can be concluded that the kinematic model of the parallel mechanism was correct,and the validity of the model was further verified by the simulation analysis on Vernal Equinox day.（4）The prototype of tracking device with parallel mechanism was manufactured and assembled.Then the whole solar tracking system for independent power generation was designed,completing the tracking control base on the example on Vernal Equinox day.It was concluded that the tracking limit position at sunrise and sunset was consistent with the position limit angle calculated by theory and simulation,which verified that the design of the tracking device was reliable and effective.