Research On Real-time Adjustment Method For On-orbit Focusing Of Symmetrical Two-stage Reflected SSPS

With the increasing human demands for energy sources and exhaust of fossil fuels, the exploitation of solar energy in space is becoming the priority research areas in the earth and space science. Concentration photovoltaic(CPV) technique is integrated with a large aperture concentrator in place of plane solar cells, which is the unity of economy and efficiency. The space solar power station running on the earth synchronous orbit has the advantages of all-weather work, high efficiency, low carbon and environmental protection, etc., It has become the focus of attention of national scientific and technological works. Especially with the development of photovoltaic power generation theory research, concentrating photovoltaic power generation system is getting more and more attention. Among them, Two-stage reflected concentrator has the characteristic of irradiance uniformity and proper concentration ratio, so it is suitable for the CPV system in space. In this thesis, we study on the adjustment mode of the two-stage reflected concentrator system, proposing the solution, which provides new ideas for the application development.1.the paper analyzes the present development of space power station, and put forword the symmetrical two level reflective solar energy accumulation system, after analysis the system's mathematical physics model and its advantage in space application, the paper summarizes the present research situation, and puts forward the research direction of this thesis.2.Then for the real-time adjustment of the system on orbit, we discuss it from two case: one day and one year. The earth roation, which is equivalent to the solar incident light revolve around the one level adjustment axis in 360 degree. In this time, the primary axis is rotated by the one level adjustment axis, realizing real-time tracking of the incident light of the sun, so that the solar cell array can receives the energy flow from the two one-level-axis parabolic reflector. Because of the earth revolution, The incident solar light change in degree of-23.45 to +23.45, according to the theory of the obliquely incident light induced parabolic defocusing,the deflecting angle only can be very small, otherwise will cause severe defocus, it can cause the energy efficiency of the battery plate array lowly, in order to solve this problem, this paper proposes a “focus tracking”adjustment method. By adjusting the parabolic reflector to achieve the focus of the light, and then adjust theposition and the angle of the two level circular plane mirror to achieve the two reflection of the light, the light will be as large as possible hit on the solar array cell. Through the derivation of focus tracking method, the specific motion trajectory information is obtained.3.Using soildworks 3D modeling method and optisworks optical simulation, we get two kinds of simulation: one day and one year, we can get the distribution of the energy density on the cell array, and we analyze the energy flow density of the solar array. We can not only use the conventional method to determine the distribution of energy flux density, but also analyze the fluctuation of the energy density data from the view of variance and standard deviation. Through the analysis, we can get the conclusion of the distribution of the solar cell array is good on the adjustment process of one day and one year. So the real-time adjustment method is effective, and it suitable for the space of symmetric two level reflection solar power station in the full year real-time adjustment, and can achieve the best energy flow on the solar array.