Energy conversion materials for the space solar power station

Since it was first proposed,the space solar power station(SSPS)has attracted great attention all over the world;it is a huge space system and provides energy for Earth.Although several schemes and abundant studies on the SSPS have been proposed and conducted,it is still not realized.The reason why SSPS is still an idea is not only because it is a giant and complex project,but also due to the requirement for various excellent space materials.Among the diverse required materials,we believe energy materials are the most important.Herein,we review the space energy conversion materials for the SSPS.

Multi-Layer and Multi-Objective Optimization Design of Supporting Structure of Large-Scale Spherical Solar Concentrator for the Space Solar Power Station

Space solar power station is a novel renewable energy equipment in space to provide the earth with abundant and continuous power.The Orb-shaped Membrane Energy Gathering Array,one of the alternative construction schemes in China,is promising for collecting space sunlight with a large-scale spherical concentrator.Both the structural and optical performances such as root mean square deformation,natural frequency,system mass,and sunlight blocking rate have significant influences on the system property of the concentrator.Considering the comprehensive performance of structure and optic,this paper proposes a novel mesh grid based on normal polyhedron projection and spherical arc bisection for the supporting structure to deal with the challenge of the large-scale structural modular design.For both achieving low system mass and high surface precision,a multilayer and multi-objective optimization model is proposed by classifying the supporting structure into different categories and optimizing their internal and external diameters.The Particle Swarm Optimization algorithm is adopted to find optimal sectional dimensions of the different kinds of supporting structure.The infinite model is also established and structural analysis is carried out,which are expected to provide a certain reference for the subsequent detailed structural design.The numerical results indicate that the spherical concentrator designed by the novel mesh grid would obtain as high as 94.37%sunlight collection efficiency.The supporting structure constructed with the multiple layers would reduce the system quality by 6.92%,sunlight blocking rate by 28.54%,maximum deformation by 41.50%,and root mean square by 9.48%to the traditional single layer,respectively.

Microwave Power Transmission for Space-Based Solar Power (MPT-SBSP)

This paper examines the definition of MPT-SBSP and implementation model of such technology.It surveys the latest development and affirms the feasibility and a bright future of this technology,emphasizing the existing issues must be solved by more educated individuals and organizations for the early realization of this"beyond-the-realm-of-cost"technology.Because once this technology is successfully applied in large-scale,humans won’t have to worry about the energy crisis in the future.

Technology Roadmap for Space Solar Power Proposed by Chinese Scientists

As a result of Japan raising the alert level at its quake-damaged nuclear plant from four to seven on a seven-point international scale of atomic incidents,which was caused by the 9.0-magnitude earthquake

Distributed power conditioning unit of large-scale space solar power station

In this paper,a multi-bus distributed Power Conditioning Unit(PCU)is proposed for the Space Solar Power Station with large scale photovoltaic(PV)array and power levels reaching MW level.In this unit,there are multiple independent PV arrays.In each PV array,there are multiple independent PV subarrays.In this paper,a V-P droop control method with adaptive droop coefficient is proposed,which modifies the droop intercept based on the bus voltage deviation and the power per unit value of the PV array.This method ensures the accuracy of bus voltage and achieves proportional distribution of power between PV arrays based on the proposed topology structure in this paper.When the load changes or the output power of the PV array fluctuates,this method can ensure that power is distributed proportionally.The principle and control method of the proposed droop control method is analyzed in this paper.The effectiveness of the method is verified through MATLAB/Simulink simulation and experiment.Simulation and experimental results show that the proposed method can achieve power distributed proportionally when load changes and PV output power fluctuates,reduce bus voltage error caused by line impedance and differences in rated power of different PV arrays,and improve the performance of PV power generation system applied to space.

Study on Multi-Rotary Joints Space Power Satellite Concept

The Space Power Satellite(SPS) would be a huge spacecraft capturing the power of solar radiation in space and to supply electric power to the electric grid on the ground. The SPS concept was proposed by Dr. Peter Glaser in 1968. SPS have been studied now for exactly fifty years by many scientists in various countries. It has been regarded as one of the most promising energy projects of the future and has been attracting more attention in recent years. More and more Chinese scholars and experts are paying attention to the development of SPS. Due to the huge size, immense mass and high power of such a satellite system, there are many technical difficulties which exist to realize SPS. In this paper, recent SPS research and development activities are reviewed first. Various SPS concepts are analyzed and compared. The primary scheme of the Multi-Rotary joint SPS(MR-SPS) is described. The main feature is that the huge solar array comprising many separate small solar sub-arrays and each solar sub-array has two middle power rotary joints. So, the most challenging technology, the high-power rotary joint, is simplified by using many middlepower rotary joints hence the possibility of a single-point failure of a single rotary joint is avoided. This enables easy assembly of the modular solar arrays. Finally some key technologies of MR-SPS are analyzed.

Technical challenges of space solar power stations:Ultra-large-scale space solar array systems and space environmental effects

Space solar power station(SSPS)are important space infrastructure for humans to efficiently utilize solar energy and can effectively reduce the pollution of fossil fuels to the earth’s natural environment.As the energy conversion system of SSPS,solar array is an important unit for the successful service of SSPS.Today,solar arrays represent the standard technology for providing energy for spacecraft,thanks to their high conversion efficiency and reliability/stability in orbit.With the development of solar arrays,many new materials,new photovoltaic devices and new control systems have emerged.Solar arrays are directly exposed to the space environment,and harsh environmental factors can degrade the performance.To ensure the long-term safe inorbit service of SSPS as well as its ultra-large solar array,these new materials,devices,and control systems must operate certification and evaluation that can be used in space applications.In this review,the development history and research progress of SSPS and the corresponding space solar arrays are summarized and discussed,and the space environmental effects of solar arrays are analyzed at multiple levels(materials,devices,and systems).Finally,in response to the current space environmental effects of the ultra-large solar array used in the SSPS,future development trends and challenges are proposed.

Theoretical and experimental studies of retro-reflective antenna array for microwave power transmission from space solar power satellite to earth

The development of space solar power satellites aims to harvest solar power by artificial satellites over the earth’s geostationary orbit and then deliver the harvested power to the earth wirelessly.The retro-reflective antenna array technique is believed to be a close-to-optimal technical approach to achieve efficient wireless power transmission from a geostationary satellite to the earth,as it is capable of generating a microwave power beam aiming at a ground station on the earth via analyzing a pilot signal broadcasted by the ground station.In this paper,some of our preliminary research outcomes on retro-reflective antenna array for space solar power applications are reported.In the theoretical part of this paper,closed-form formulations with precision better than the classic theory of phased array are derived to analyze the performance of retro-reflective antenna array when the far zone condition is not satisfied between the space solar power satellite and the ground station.In the experimental part of this paper,a bench-scale retro-reflective antenna array with physical dimensions of about 0.6 m by 0.6 m is fabricated and tested.The theoretical and experimental results demonstrate that the microwave beam generated by a satellite-borne retro-reflective antenna array could be adjusted in real time to aim at the location from which the pilot signal stems.Based on the theoretical and experimental studies of this paper,systematic research endeavors are being conducted on the retro-reflective antenna array for space solar power applications.

Research on PV array reconstruction and Full-cycle maximum power point tracking technology of space solar power station

Space solar power station is an energy system that converts solar energy into electrical energy in the space environment and then transmits it to the space platform or ground using wireless power transmission technology.To improve the power generation and system efficiency of the space solar power station,an adaptive and reconfigurable photovoltaic array with multi-configuration is proposed,which can avoid large attenuation of the output power and efficiency of the photovoltaic array when the photovoltaic modules have a fault occurs or the receive different irradiation intensity.Then,according to the orbit area and light condition of the space solar power station,the operation mode are divided in detail.Furthermore,a novel full-cycle and multi-mode GMPPT(maximum power point tracking)strategy is proposed.Compared to the single mode MPPT,the control strategy has shorter response time,faster convergence and higher tracking accuracy.Through the above research,the output power and photoelectric conversion efficiency of space solar power station can be significantly improved.

SSPS太阳能收集系统研究现状及发展趋势

为研究太阳能收集系统在未来空间太阳能电站(SSPS)中的发展和应用,对比和分析国内外典型系统设计方案的结构特点、光收集特性及优、缺点,展望空间太阳能电站太阳能收集系统的发展趋势,并提出对新材料、新结构、新技术、新理论和新方法的发展和应用需求。

Impact of solar cell failure on the performance of solar arrays in space

Space solar power station adopts large-area solar arrays for efficient photovoltaic conversion,making it one of the best solutions to future energy problems.In-orbit failure of solar arrays can affect the service life of spacecraft,thereby it is crucial to comprehend the impact of solar cell failure on the electrical performance of solar arrays and propose appropriate circuit design criteria.The root cause of solar array failure is the degeneration of solar cells.In this paper,power loss caused by an open circuit or short circuit failure of solar cells in pure parallel and series–parallel circuits is described,and it reveals that an open circuit of the cell is more harmful in the pure parallel circuit,while a short circuit in the series–parallel circuit is more detrimental,which causes loss of electrical performance in series and parallel units,respectively.All conclusions have been validated through model calculations and corresponding experiments.The electrical loss is also influenced by the control mode.For the Maximum Power Point Tracking control mode favored by space solar power station,which can significantly increase generated power,application suggestions have been proposed based on the results of cell failure analysis.The research will provide a reference for circuit selection and boundary design for solar arrays,reducing the probability of solar array failure and saving the manufacturing and redeployment costs of space solar power station.

SSPS-OMEGA超大型球形聚光器结构拓扑构型与设计

为同时兼顾千米量级尺度空间太阳能电站聚光系统的在轨发射安装难度、光学收集效率、稳定性及结构工艺等多方面的因素,提出采用基于球面正多面体的经纬线划分法模块化构建球形聚光器。该方法不仅可实现基础划分单元分布均匀、规格种类少,降低在轨构建与运载发射难度。而且只要合理控制弧高等分数和基础划分单元的口径就可以同时保证聚光系统的光学收集效率。理论与仿真结果显示,当弧高等分数为24时,该划分法共有25种基础单元件,整个球面被分成5762块。并且此时模块化构建的实际球形聚光器的光学收集效率与理想球面相比基本保持不变,解决了太阳能电站聚光系统设计中存在的关键问题。

A review of dynamic analysis on space solar power station

The concept of a space solar power station(SSPS)was proposed in 1968 as a potential approach for solving the energy crisis.In the past 50 years,several structural concepts have been proposed,but none have been sent into orbit.One of the main challenges of the SSPS is dynamic behavior prediction,which can supply the necessary information for control strategy design.The ultra-large size of the SSPS causes difficulties in its dynamic analysis,such as the ultra-low vibration frequency and large fexibility.In this paper,four approaches for the numerical analysis of the dynamic problems associated with the SSPS are reviewed:the finite element,absolute nodal coordinate,foating frame formulation,and structure-preserving methods.Both the merits and shortcomings of the above four approaches are introduced when they are employed in dynamic problems associated with the SSPS.Synthesizing the merits of the aforementioned four approaches,we believe that embedding the structure-preserving method into finite element software may be an effective way to perform a numerical analysis of the dynamic problems associated with the SSPS.

3D打印在大规模空间建造中的应用

3D打印作为代表国家航天实力的重要技术之一,在太空事业的发展中扮演着至关重要的角色。通过利用空间3D打印技术,我们能够摆脱地面制造带来的约束与限制,从而降低在地球上进行预制并将其运送到太空的成本和风险,为未来开展多样化、超大尺寸的空间结构提供了新的机会。3D打印技术可以在太空中直接制造出大型天线结构和太阳能电站,从而不再受限于地面制造的大小和重量,这将为太空资源的利用和未来太空探索提供更加灵活、高效的解决方案。文章阐述了空间3D打印技术的起源及发展背景,围绕其在太空环境的应用情况分别讨论了国内外开展空间3D打印技术在轨制造、构建大型空间结构以及星球基地等方面的研究进展;明确了相关技术在当前发展中的主要特点及问题,并阐述了其未来的发展方向;最后结合当前各国技术的发展和研究成果,提出了中国未来在太空中构建大规模空间天线和空间太阳能电站的研究设想,为我国太空3D打印技术在轨制造应用提供了借鉴和指引。

太空电站充电时基于真实手臂模型的SAR分析

空间太阳能电站所提供的将是高功率的电磁能量,在执行无线供电的过程中,将会在被供电设备上再次激励起不同频率的电磁波,对人体健康产生一定的威胁。对于低频的电磁波可以将人体整体等效为一个简易模型,分析电磁波对人体健康的影响。但是,当频率逐渐升高,其波长将和人体的局部组织尺寸可比拟,此时必须采用真实的人体模型才能更精确地分析电磁波对人体的影响。为此,文章研究5.8GHz频率下,基于真实手臂模型的比吸收率。利用平面波照射真实手臂模型,分析手臂表面以及透射到各个关键局部区域体积内的SAR值,可为高频率情况下电磁波对人体健康的影响提供一定的参考。

无线电能传输技术在空间太阳能电站中的研究与应用现状分析

空间太阳能电站是高效利用太阳能以解决当下严峻的能源危机的有效途径,如何实现电能从空间太阳能电站到地球的空-地传输是关键。无线电能传输技术可实现电能的非接触传输,并且具有较高的安全性、可靠性和便捷性,是解决空-地电能传输问题的有效措施。对无线电能传输技术在空间太阳能电站中的研究与应用现状进行了分析,并据此阐述了亟待解决的瓶颈问题和待进一步发展的关键技术,旨在为后续相关科研工作者提供参考和指导。

基于变遗忘因子的空间太阳能电站时变频率辨识

考虑空间太阳能电站(SSPS)在轨运行时帆板旋转所导致的系统变构型特征,提出一种变遗忘因子广义子空间跟踪器(VFF-GYAST)递推辨识方法,在轨辨识该时变动力学系统的模态频率参数,以提高GYAST方法对于这类时变系统的跟踪能力。基于模态综合技术和子结构方法,建立多旋转关节构型SSPS(MJ-SSPS)的时变姿态-振动耦合动力学方程;根据投影子空间理论,通过计算系统均方差来确定递推过程中的时变遗忘因子,以提高GYAST方法的跟踪性能并辨识得到系统的时变伪模态频率参数。数值仿真结果表明:所提方法能够有效地识别该大型柔性系统的时变频率参数。与传统的递推子空间方法相比,所提方法具有较高的抗噪声干扰能力,在低量测信噪比时所提方法对于频率辨识结果的相对误差的平均值小于5%,且对时变系统的跟踪性能优于基于固定遗忘因子的原始方法。

激光无线能量传输远场大光斑测试技术

无线能量传输系统作为空间太阳能电站的一个关键部分,其性能直接决定了空间太阳能电站技术的可行性。特别对于激光无线能量传输系统,准确测量激光远场光斑分布是分析和评价激光无线能量传输系统性能的有效手段。针对太阳能发电卫星轨道高、激光传输距离远、接收激光光斑面积大,并且受大气影响,光斑抖动严重,光斑能量分布以及光斑形状测量困难的问题,文章提出了基于光能探测器阵列的大面积激光光斑测试方法,采用光斑分布式测量及能量分布重构方法,完成激光无线能量传输系统远场光斑的测试,具有分布式测量,可灵活布局的特点,通过反演算法能够实现光斑能量密度分布重构,接收激光功率积分求解,光束发散角计算等,功能多样,适应能力强,为激光无线能量传输系统载荷的参数修订,以及在轨飞行任务的评价提供有效依据。

Effect of operational condition of rotational subsystem on attitude control for space solar power station

Space Solar Power Station(SSPS)is a giant spacecraft to collect space solar energy and transmit electric energy to the ground by using the wireless transmission technology.As a concentrated space solar power station,SSPS via the Orb-shape Membrane Energy Gathering Array(OMEGA)system is comprised of the concentrator subsystem,the photovoltaic array subsystem and the transmitting antenna subsystem.In this manuscript,the comprehensive study on the coordinate kinematic among subsystems is carried out.Firstly,kinematic analysis and dynamic analysis are conducted.Secondly,under the condition of ideal attitude,the influence of the moving condition of the Photovoltaic(PV)array on the overall system is studied.Finally,the control ability for the deviation attitude caused by the acceleration process of the photovoltaic array is studied.The simulation results demonstrate the serious influence of the angular acceleration of the photovoltaic array on the system’s attitude and the validity of the designed attitude control system.

模块化多旋转关节空间太阳能电站方案设计

文章基于多旋转关节空间太阳能电站(MR-SPS)方案,以降低远距离高压电力传输技术难度为核心,提出一种更新的模块化多旋转关节空间太阳能电站概念。该方案在分布式太阳电池分阵和多导电旋转关节基础上,对于微波发射天线阵也进行了模块化设计和分布式布局,实现了太阳电池分阵和微波发射天线分阵的一一对应,形成多个独立的太阳能发电与能量传输模块,通过模块的扩展实现整个空间太阳能电站。该方案大幅简化了空间电力传输与管理的复杂性和在轨组装的难度。同时各个模块完全独立,组装后即可单独工作,也提高了系统的可靠性。