Solar Satellite Research Articles

Power-Optimal Guidance for Planar Space Solar Power Satellites

This paper presents power-optimal guidance for a planar space solar power satellite (SSPS). Power-optimal guidance is the attitude trajectory that maximizes the solar power transmitted by the SSPS. Planarity is important because it couples the orientations of the SSPS’s photovoltaic and antenna surfaces. Hence, the transmitted power depends on the relative geometry between the SSPS, the sun, and the receiving station. The orientation that maximizes power transfer changes as this relative geometry changes. Both single- and dual-sided SSPS architectures are considered. A single-sided SSPS has one photovoltaic surface and one antenna surface. A dual-sided SSPS is a single-sided SSPS with at least one additional photovoltaic or antenna surface. Geometric arguments show that a dual-sided SSPS has superior performance to a single-sided SSPS. Power-optimal guidance is then presented for the special cases of SSPSs in geostationary Earth orbit, medium Earth orbit, and low Earth orbit transmitting to an equatorial receiving station at the time of Earth’s vernal equinox. These examples emphasize important solution properties, including the need for large slew maneuvers, and they show that, even though system efficiency decreases as orbit altitude decreases, reduced path losses actually increase the amount of received energy per unit aperture area. This has significant system implications for future space solar power missions.

Numerical investigation on improvement of energy transfer in solar power satellite

Solar power satellite (SPS) normally collects sunlight through concentrating solar collectors give to PV cells which convert it to electric power and then transmitted it to the earth by microwave energy. SPS-ALPHA Mark-Ⅱ applies conical structural as the whole frame composed by several thousands of hexagonal “Reflectors and Deployment Modules” (RDM) that enables extremely high modularity and low cost of machining/space transport. SPS-ALPHA system, on the whole, can be treated a dense array concentrated photovoltaic (DA-CPV) system. The blocking shadow effect and cosine effect of ray path exist that make the optical efficiency fluctuate with different tracking angles, resulting the trade-off exists between optical efficiency and irradiance uniformity. The current study aims to find a compromise solution: a high optical efficiency with stable irradiance distribution for effective PV layout design. To meet this target, Ant Colony Optimization (ACO) algorithm combined with dynamic source-target mapping was adopted to find suitable aiming vectors of modular reflectors. The optical transmission characteristics were investigated using Monte-Carlo ray tracing (MCRT) method. Using above method, this article will focus on the effects of tracking conditions, structural and RDM parameters of SPS-ALPHA Mark-Ⅱ thereby provide basic data and reference for engineering constructions in next step.

Optical study of a cocktail structural Space-based Solar Power Station

SPS-ALPHA as the most innovative and practical concept of Solar Power Satellite (SPS), has been widely concerned in the world. It adopts axisymmetric sigmoid curve-based/cocktail shape as the entire structure composed by several thousands of hexagonal “Reflectors and Deployment Modules” (RDM) that enables extremely high modularity and low cost of machining/space transport. SPS-ALPHA system, on the whole, can be treated as a dense array concentrated photovoltaic (DA-CPV) system. The blocking shadow effect and cosine effect of ray path exist that make the optical efficiency fluctuate with different tracking angles, resulting the trade-off exists between optical efficiency and irradiance uniformity. The current study aims to find the optimal design parameters of RDM when high optical efficiencies and stable irradiance distribution are both achieved for effective PV layout design. To meet this target, Ant Colony Optimization (ACO) algorithm combined with dynamic source-target mapping was adopted to find suitable aiming vectors of modular reflectors. The optical transmission characteristics under different incident degrees were investigated using a two-step Monte-Carlo ray tracing (MCRT) method. Afterwards the optimized results and sensitivity analysis for RDM would be undertook. The article can provide basic data and reference for engineering constructions of SPS-ALPHA in next step.

Gyroscopic Solar Power Satellite with the New Thermal Conversion System and Superconductive Generator

Gyroscopic Solar Power Satellite with the New Thermal Conversion System and Superconductive Generator

Gravity-Gradient-Induced Transverse Deformations and Vibrations of a Sun-Facing Beam

Ultralarge sun-facing structures are adopted in many large spacecraft, such as solar power satellites. The in-plane transverse steady deformations and vibrations of a large sun-facing beam induced by the gravity gradient are studied considering geometric nonlinearity. First, the problem is divided into a static problem when the beam maintains a constant pitch attitude angle, and a dynamic problem when the beam maintains a sun-facing attitude. For the static problem, three static models are established to study the gravity-gradient-induced steady deformations. An analytical solution is obtained in small deformation cases, which reveals the influences of the parameters of the orbit and the beam on the steady deformations. The influence mechanism of the geometric nonlinearity in large deformation cases is studied using geometrically exact beam theory and absolute nodal coordinate formulation. For the dynamic problem, four dynamic models are built to investigate the gravity-gradient-induced vibrations. According to the numerical results, a novel resonance is induced by the gravity gradient and the geometric nonlinearity when the lowest natural frequency of the beam is approximately four times the orbital frequency in circular orbit, which is found for the first time. The resonance must be considered seriously in structural design of large sun-facing structures.

Fracture analysis of superconducting composites with a sandwich structure based on electromagnetic–thermal coupled model

This paper analyzes a multilayer structure with a superconducting layer in the center and strengthening layers in the outer part. This represents a generalized structural form of multilayered high-temperature superconducting cable structures for space solar power station application. An analytical model for considering the influences of thermal–mechanical–electrical–magnetic coupling and the temperature on the stress distribution will be developed. The superposition method is used to solve the temperature distribution problem. After the temperature field is calculated, the magnetic field using a critical state model that considers the temperature effect will be developed. Finally, we analyzed the influence of material properties on the thermal and magnetically induced stress intensity factors in trapped field, zero field cooling and field cooling. Results show that the stress intensity factors induced either by thermal stress or by the Lorentz force must not be neglected. If the elastic module or the thickness of substrate layer increases, the stress intensity factor induced by thermal stress increases, while the one induced by the Lorentz force declines. Importantly, when reducing the thickness of the substrate layer, the total stress intensity factor will decrease at the early stage of heat conduction but increase at the late stage of heat conduction. This fact indicates that that thicker substrate layer is not always good from the reliability point of view.

Distributed adaptive vibration control for solar power satellite during on-orbit assembly

The distributed adaptive vibration control for solar power satellite (SPS) during on-orbit assembly is investigated in this paper. Focusing on the platform configuration SPS, the different control units (CUs) and relationship matrices, that describe the topology of whole SPS structure, are firstly defined, and the dynamic model of the CU is proposed through the relationship between the CU and the whole SPS structure. Using the linear quadratic optimal control technique, the adaptive controller of the CU is designed to suppress vibrations, and a compensatory component is included in the controller to deal with the interactions with the whole structure. The closed-loop distributed control system is then developed in the presence of the impact at the specific assembling location, which needs to adaptively update along with the varying dynamic model of the SPS structure during on-orbit assembly. The asymptotic stability of the closed-loop distributed system is investigated, and two representative numerical cases are finally provided. The results demonstrate that the proposed distributed adaptive controllers can significantly suppress the vibration caused by the impact among SPS modules during on-orbit assembly.

Improved perturb and observe maximum peak power tracking for solar satellite systems

The aim of this work is to solve partial shading problem in solar panels to detect the global peak power point that can be used in satellite systems. This can be done by proposing a modified perturb and observe control algorithm depends on comparing all the local peak power points in photovoltaic system to detect the global one, by making initial estimation to the duty cycles of the corresponding local peak power then using perturb and observe to make fine tuning to reach the exact local peak points when oscillations happen. Also to detect the oscillations theory of operation of incremental conductance algorithm is used depending on the difference between incremental conductance and the instantaneous conductance values. The idea of operation is verified using boost converter applied in Matlab/Simulink showing good results. Also variable duty cycle is used to solve the problem of oscillations in output power.

“Power Transmission through Solar Power Satellite to Earth Surface with Minimum Power Loss”

Now days, expanding needs of photovoltaic cells and other solar oriented power establishments are in administration around the globe and in space. These utilizations extend from essential electric power source for satellites, remote site logical experiment and towns in creating nations to enhancing the commercial electric grid and giving fractional power for individual organization. In space, power produced by photovoltaic cells after conversion from sunlight will become mainstay of power source for Earth and geostationary satellite bodies. The conspicuous reason is daylight on earth is excessively untrustworthy, whereas in space energy can be harvest by 24 hours. The challenge is to harvest maximum energy and transmit the energy from space to earth in the form of microwave frequency with minimum power loss. In this work to harvest maximum power,s we change the directivity range of receiving antenna to -40 dB, Received microwave frequency from transmitting antenna is in the form of beam of rectangular array, In previous work, directivity ranges from 0 to -8 dB for receiving frequency 70.00 MHz causes cutoff of transmitted frequency for below 2.45 GHz, if directivity ranges increase from 0 to -40 dB then transmitting frequency ranges till 2.00 GHz will be utilized by which after conversion in rectenna we get total 223.42 MW power.

Optical-Structural Integrated Optimization Design of Deployable Beams in OMEGA Space Solar Power Satellite

AbstractThe efficiency of a solar energy collection (SEC) is of great significance to the power generation and overall efficiency of a space solar power satellite (SSPS). The Orb-Shape Membrane Ene...

Toward the Realization of Space Solar Power Generation Systems with Microwave Power Transmission Technologies

1．はじめに

Numerical and experimental research of the characteristics of concentration solar cells

The development of automatic tracking solar concentrator photovoltaic systems is currently attracting growing interest. High concentration photovoltaic systems (HCPVs) combining triple-junction InGaP/lnGaAs/Ge solar cells with a concentrator provide high conversion efficiencies. The mathematical model for triple-junction solar cells, having a higher efficiency and superior temperature characteristics, was established based on the one-diode equivalent circuit cell model. A paraboloidal concentrator with a secondary optic system and a concentration ratio in the range of 100X–150X along with a sun tracking system was developed in this study. The GaInP/GalnAs/Ge triple-junction solar cell, produced by AZUR SPACE Solar Power, was also used in this study. The solar cells produced by Shanghai Solar Youth Energy (SY) and Shenzhen Yinshengsheng Technology Co. Ltd. (YXS) were used as comparison samples in a further comparative study at different concentration ratios (200X–1000X). A detailed analysis on the factors that influence the electrical output characteristics of the InGaP/lnGaAs/Ge solar cell was conducted with a dish-style concentrating photovoltaic system. The results show that the short-circuit current (Isc) and the open-circuit voltage (Voc) of multijunction solar cells increases with the increasing concentration ratio, while the cell efficiency (ηc) of the solar cells increases first and then decreases with increasing concentration ratio. With increasing solar cell temperature, Isc increases, while Voc and ηc decrease. A comparison of the experimental and simulation results indicate that the maximum root mean square error is less than 10%, which provides a certain theoretical basis for the study of the characteristics of triple-junction solar cell that can be applied in the analysis and discussion regarding the influence of the relevant parameters on the performance of high concentration photovoltaic systems.

Spectrometer of hard X-ray imager payload onboard the ASO-S mission

A spaceborne hard X-ray spectrometer, composed of an array of 99 scintillation detectors and associated readout electronics, has been developed for the hard X-ray imager (HXI). The HXI is one of the three payloads onboard the advanced space-based solar observatory (ASO-S), which is scheduled to be launched in early 2022 as the first Chinese solar satellite. $$\hbox {LaBr}_3$$ scintillators and photomultiplier tubes with a super bialkali cathode are used to achieve an energy resolution better than 20% at 30 keV. Further, a new multi-channel charge-sensitive readout application-specific integrated circuit guarantees high-frequency data acquisition with low power consumption. This paper presents a detailed design of the spectrometer for the engineering model of the HXI and discusses its noise and linearity performance.

Wireless Power Transmission: State of the Art and Perspectives

This paper deals with Wireless Power Transmission (WPT), and its main futuristic application, Space-based Solar Power (SSP). In the first part, the decisive role played by physicist Nikola Tesla in the development of electricity industry, his major concrete contributions, and his prophetic intuitions concerning wireless power are presented. The basics of the physics of the domain are also recalled. In the second part, the main experiments led until now in the domain of WPT are presented, as well as the different technical approaches available in the field. A few current applications of WPT at low power are briefly described. In the third part, a survey of the actual state of SSP projects is presented.

Solar-based Satellite Power System: An Overview

Abstract: In this paper, describes about advancement in solar-based power system in satellite. A thrust which provides a back force to satellites that move in upward direction and get satellites help to generate power in space. This power transmits to the earth via wireless power transmission and such type of satellite called space based solar power satellite. In recent time, electrical propulsion system has used mostly in place of chemical propulsion system for satellite. Solar energy collected from the space and converts into DC then transmit power from the space to earth wireless and then send to electric grid system. Solar energy is also used by the thruster elements in DC. Keywords: WPT (wireless power transmission), SBSP, propellant, propulsion Cite this Article Divyanshi Srivastava, S.K. Srivastava. Solar-based Satellite Power System: An Overview. Journal of Thermal Engineering and Applications. 2019; 6(1): 20–23p.

A flexible phased array system with low areal mass density

Phased arrays are multiple antenna systems capable of forming and steering beams electronically using constructive and destructive interference between sources. They are employed extensively in radar and communication systems but are typically rigid, bulky and heavy, which limits their use in compact or portable devices and systems. Here, we report a scalable phased array system that is both lightweight and flexible. The array architecture consists of a self-monitoring complementary metal–oxide–semiconductor-based integrated circuit, which is responsible for generating multiple independent phase- and amplitude-controlled signal channels, combined with flexible and collapsible radiating structures. The modular platform, which can be collapsed, rolled and folded, is capable of operating standalone or as a subarray in a larger-scale flexible phased array system. To illustrate the capabilities of the approach, we created a 4 × 4 flexible phased array tile operating at 9.4–10.4 GHz, with a low areal mass density of 0.1 g cm^(−2). We also created a flexible phased array prototype that is powered by photovoltaic cells and intended for use in a wireless space-based solar power transfer array.

Distributed vibration control of a large solar power satellite

To deal with the vibration problem of the solar power satellite (SPS), the distributed vibration control approach is investigated in this paper. Taking the Multi-Rotary joints SPS as the research objective, the control unit (CU) and the location relationship matrix are firstly defined for distributed controller design according to the configuration of SPS. The dynamic model of each CU is therefore established based on the finite element method. The dynamic model of the whole SPS structure is then developed using the CU models, and is updated along with on-orbit assembly. The distributed cooperative controller, using proportional and differential feedback and the interaction feedback among adjacent CUs, is proposed to suppress vibration. The close-loop distributed cooperative control system is then achieved by integrating all distributed controllers, and the asymptotic stability is proofed by the Lyapunov’s stability theorem. To verify the feasibility of the proposed control system, three numerical cases are finally presented. The results demonstrate that the distributed cooperative controllers can effectively suppress vibration during on-orbit assembly and operation after assembly, and the closed-loop system has good fault tolerance.

Solar ray collection rate fluctuation analysis with Monte Carlo Ray Tracing method for space solar power satellite

According to the ideal optical design, the spherical concentrator made by the semi-transparent and semi-reflecting thin film is used in SSPS-OMEGA system. To obtain the continuous power, the PV array should rotate around the spherical concentrator to point the sun when SSPS-OMEGA rotate around the earth on GEO. However, considering the in-orbit assembly, the concentrator is assembled by many planar elements to be approximate to the ideal spherical concentrator. The solar ray collection rate fluctuates in certain scope because the original solar ray path is changed. In addition, planar element is deformed easily by the rotating PV array, which also lead to the fluctuation because the position of the planar element is changed. In this paper, the spherical concentrator is divided into many planar elements by using equal latitude and longitude method. It is studied that the relationship between the number of division layers and the collection rate fluctuation by using Monte Carlo Ray Tracing method. The simulation results indicate that with increasing dividing layers, the collection rate increases and the fluctuation amplitude decreases, which ranges 80.72–83.70% (2.98%) of 24-layers concentrator, ranges 88.45–89.91% (1.47%) of 48-layers concentrator, and ranges 92.46–93.80% (1.33%) of 72-layers concentrator. To solve the deformation of the concentrator, the flexible multibody dynamics model of SSPS-OMEGA is established. Combing the deformation and Monte Carlo Ray Tracing method, it is studied that the relationship between the deformation of the concentrator and the collection rate. The simulation results indicate that the stiffness of 72-layers concentrator is better than 24-layers concentrator and 48-layers concentrator, and the reduction of the collection rate of 72-layers concentrator, which is 0.4%, is less than 24-layers concentrator (1.57%) and 48-layers concentrator (0.81%).

CASSIOPeiA – A new paradigm for space solar power

Recent debate (Clack v. Jacobson, 2017) argues the feasibility of 100% terrestrial renewables (wind, water, solar) by 2050, on the premise of restricting world consumption to 2012 levels (∼12 TW-years). Given the expected population rise by 3 billion over the same time frame, and the correlation between prosperity and energy availability – are we to impose energy equality, requiring some to reduce consumption by 87%, or are we to condemn the majority to relentless poverty? Choosing neither implies ever-increasing carbon emissions and the risk of catastrophic climate change. Nuclear fission is one energy technology which could be expanded to provide sufficient carbon-free power, but faces widespread opposition from public fear and distrust. Future terrestrial fusion is another, but first pilot operations are not expected until 2050 – which may be too late. We could make much better use of one existing fusion power source, our Sun. The fundamentals of Space Solar Power (SSP) are well understood and could lead to a world of energy abundance; the deliverable energy from just a 10 km geostationary (GEO) band exceeds 570 TW-years – enough to supply ten billion people at six-times current US per-capita levels. Despite this, SSP has languished for fifty years. GEO is one of few candidates for baseload power, but physics dictates a kilometre-scale microwave transmitter irrespective of the power delivered – hence economics favours the multi-gigawatt (per-satellite) engineering limit. Given the complexity of the differentially rotating solar collector, sub-gigawatt SSP suffers both economically and technically, with different solutions required at different scales – which has led to exorbitant (hence prohibitive) start-up costs. CASSIOPeiA breaks this non-scaling paradigm by eliminating the rotating interfaces; all SPS subsystems are able to share one lightweight modular structure, with near-invariant areal power density from sub-megawatt to gigawatt systems. With additional fixed mirror concentrators, CASSIOPeiA can also be expanded into the multi-gigawatt regime. CASSIOPeiA's unique beam-steering capability facilitates baseload delivery from alternative, closer orbits, with the possibility of single payload deployment requiring no on-orbit assembly. By starting with sub-megawatt, near-term stratospheric station-keeping platforms – with retrieval, servicing and transfer of gained knowledge – the era of SSP may commence at much lower risk and expense.

Sensor placement algorithm for structural health monitoring with redundancy elimination model based on sub-clustering strategy

Abstract Considering the limitation of selecting several neighbor sensors in a local region similar to just single one, namely redundant information, a sensor placement algorithm for structural health monitoring is proposed based on sub-clustering strategy, in order to improve the performance of sensor configuration with less redundancy. According to the significance of redundancy, the proposed novel redundancy elimination model considers global and local effect to overcome the previous limitations in sensor distribution. Based on the sub-clustering strategy, the redundancy elimination model reflects the sensor configuration in each sub-clustering and overall structural field. The presented sub-clustering strategy for sensor placement includes three main procedures: sub-clustering algorithm, its check step and smallest enclosing circle method, thus the accuracy can be guaranteed. Combining the effective independence method with normalization and weighting factor, the proposed sensor placement algorithm can balance performance and redundancy by using genetic algorithm, which is more competitive to reduce the order difference between the two objectives. Finally, the effectiveness of the proposed redundancy elimination model is verified by a simple example, and another two engineering numerical examples including space solar power satellite and re-usable launch vehicle are applied to demonstrate the validity of the proposed sensor placement algorithm respectively.