Research On Backtracking Technology Solar Tracker System And Its Application

Solar photovoltaic(PV)power generating system is widely applied in the world especially in C hina due to its cleanness and ease to be installed.However,in the process of development a lot of bottlenecks and problems are met at present.It is necessary to improve the solar system output in order to achieve grid parity and changing the PV panel mounting structures from the current southern-faced fixed system into tracking system will lead to an increase of electricity output by 10-30%.Horizontal single axis tracking system is applied worldwide.The Backtracking technology suggested in this thesis can improve electricity output by reducing the distance between the rows of horizontal single axis tracking system and eliminating the shadows between each other.C hina N ational Standard defines that solar arrays cannot be shadowed between 9 a.m.to 3 p.m.in Winter Solstice Day---No shadows on PV panels in 6 hours.In Northwest of C hina,the sunlight lasts more than 9 hours even on Winter Solstice Day and the sunshine is still strong from 7 a.m.to 9 a.m.and from 3 p.m.to 5 p.m.A great portion of the PV system power generation potential will be wasted if the design is made according to the national standard.The ordinary PV tracking systems are impacted by the solar elevation and the PV arrays shadow each other out of the defined time period in the national standard.As a result,their power generation potential is wasted.O rdinary PV tracking systems operate following the sun,so they are impacted by the distance between the arrays and the latitude of them.Backtracking technology eliminates the shadows by tracking the sun reversely out of the defined time period in the national standard.This thesis intends to make a further study of the electricity output of single axis tracking system by focusing on the single axis tracking system combined with backtracking function and comparing the impact on single axis photovoltaic system with backtracking technology or without it.Based on the introduction of geometrical relationship between the sun and the earth,this thesis derives the single axis tracking system control operation principle and then introduces the typical circuit design of core hardware,system organization of the whole tracking system,and its mechanical structure including strength analysis of its main structure members.Traditional single axis tracking control algorithm,namely the astronomical algorithm based on latitude and longit ude,time,without modification of backtracking technology is analyzed in theory and the deficiency of that control algorithm is analyzed.The PVSYST simulation results verify the theoretical analys is and clarify the great engineering significance of the backtracking optimized algorithm.The backtracking optimization algorithm is improved to be more suitable for photovoltaic applications,realizes the algorithm smoothly work with no backtracking control principle,and finally comes up with the completed single axis solar tracking system based on the optimization algorithm.Based on actual data collection and analys is,the empirical result shows that the improved system overcomes the deficiency of traditional algorithm with power loss in the morning and afternoon due to shadow effects,and therefore validates the effectiveness of this optimized algorithm.