Showing papers on "Solar power published in 1989"

Survivable solar power-generating systems for use with spacecraft

Abstract: A survivable solar power-generating system for use with spacecraft is disclosed comprising optical means positioned to collect and concentrate solar energy flux, a flexible solar energy flux transmission line for conducting the concentrated solar flux towards a solar energy converter, and solar energy conversion means including an array photovoltaic cells for converting the solar energy flux to electrical power to be applied to on-board equipment of the spacecraft. A protected enclosure is positioned about the photovoltaic cells to shield them from destructive radiation and particulate matter. The transmission line includes a plurality of optical fiber waveguides whose input ends are positioned to receive the concentrated solar energy flux. Means are provided for moving the input ends of the optical fiber waveguides to optimize the quantity of concentrated solar flux entering the waveguides.

Controlled power-interface between solar cells and AC source

Abstract: A novel interface circuit between solar cells and a commercial AC bus using Van Allen's multivibrator is presented. In this circuit, the AC source is used for the backup of solar cells, and the source and load power flow is automatically balanced by the circuit itself without any external phase control. Based on an analysis of the characteristics of the oscillator, the authors describe a novel method to control the DC power from the solar cells according to the current load conditions as well as a simple and fast optimization method to derive the maximum solar power. >

Probabilistic modeling of solar power systems

Abstract: The author presents a probabilistic approach based on Markov chain theory to model stand-alone photovoltaic power systems and predict their long-term service performance. The major advantage of this approach is that it allows designers and developers of these systems to analyze the system performance as well as the battery subsystem performance in the long run and determine the system design requirements that meet a specified service performance level. The methodology presented is illustrated by using data for a radio repeater system for the Boston, Massachusetts, location. >

Solar power for the lunar night

Abstract: Providing power over the 354 hour lunar night provides a considerable challenge to solar power concepts for a moonbase. Concepts are reviewed for providing night power for a solar powered moonbase. The categories of solutions considered are electrical storage, physical storage, transmitted power, and innovative concepts. Electrical storage is the most well-developed option. Less developed electrical storage options are capacitors and superconducting inductors. Physical storage options include storage of potential energy and storage of energy in flywheels. Thermal storage has potentially high energy/weight, but problems of conduction and radiation losses during the night need to be addressed. Transmitted power considers use of microwave or laser beams to transmit power either from orbit or directly from the Earth. Finally, innovative concepts proposed include reflecting light from orbital mirrors, locating the moonbase at a lunar pole, converting reflected Earthlight, or moving the moonbase to follow the sun.

Cryogenic reactant storage for lunar base regenerative fuel cells

Abstract: There are major advantages to be gained by integrating a cryogenic reactant storage system with a hydrogen-oxygen regenerative fuel cell (RFC) to provide on-site electrical power during the lunar night. Although applicable to any power system using hydrogen-oxygen RFC's for energy storage, cryogenic reactant storage offers a significant benefit whenever the sun/shade cycle and energy storage period approach hundreds of hours. For solar power installations on the moon, cryogenic reactant storage reduces overall specific mass and meteoroid vulnerability of the system. In addition, it offers synergistic benefits to on-site users, such as availability of primary fuel cell reactants for surface rover vehicles and cryogenic propellants for OTV's. The integration involves processing and storing the RFC reactant streams as cryogenic liquids rather than pressurized gases, so that reactant containment (tankage per unit mass of reactants) can be greatly reduced. Hydrogen-oxygen alkaline RFC's, GaAs photovoltaic (PV) arrays, and space cryogenic processing/refrigeration technologies are assumed to be available for the conceptual system design. Advantages are demonstrated by comparing the characteristics of two power system concepts: a conventional lunar surface PV/RFC power system using pressurized gas storage in SOA filament wound pressure vessels and, that same system with gas liquefaction and storage replacing the pressurized storage. Comparisons are made at 20 and 250 kWe. Although cryogenic storage adds a processing plant (drying and liquefaction) to the system plus 30 percent more solar array to provide processing power, the approximate order of magnitude reduction in tankage mass, confirmed by this analysis, results in a reduction in overall total system mass of approximately 50 percent.

Heat transfer modeling of the IEA/SSPS volumetric receiver

Abstract: During the summer and fall of 1987 in Almeria, Spain, a wire-pack receiver was tested by the International Energy Agency/Small Solar Power Systems (IEA/SSPS). The basic operation of the receiver is that: air is drawn through several layers of stainless steel wire screen; concentrated solar flux is directed on the face of the screen pack; the oxidized wires absorb the solar energy; and heat is transferred to the air flowing through the screen. Although the experiment goal was strictly proof-of-concept and was not receiver characterization, modeling efforts were initiated to help understand the experimental results. The steady-state performance of the receiver is modeled using the fact that the net solar and infrared radiative energy absorbed by each screen layer must be transferred to the air by convection. Basic performance trends and typical calculations of receiver efficiency are given. Model predictions and experimentally measured temperatures and flow rates are compared.

Multi-energy resources combined drying device

Abstract: The utility model relates to a multi-energy resources combined drying device The utility model is characterized in that energy resources such as solar power, electrical energy, and heat pumps are adopted by the utility model to execute desiccation The utility model has the advantages of energy saving and stable quality The utility model can realize the continuous low temp drying and dehumidification, and the utility model can work continuously in various weather such as fine days, cloudy days, rain days, etc The utility model is suitable for the processing of agricultural, native, and aquatic products such as noodles, medicinal materials, wood, tea leaves, tobacco, etc

Wind-electricity and photoelectricily complementary device

Abstract: The utility model relates to a wind-electricity and photoelectricily complementary device, belonging to a new energy resource generator. A conventional wind force and solar power generation apparatus is used singly. The utility model is characterized in that the two classes generators are combined into an entity. One versatile controller is used together. Two choking diodes which guarantee the action of complementary are added at the part of control. Compared with the wind force and solar power generation apparatus which is used singly, the utility model has the advantages of high utilization rate, a short periodicity, long service life and low cost. An applied area is extended compared with the solar power generation apparatus with the same power.

Control method for solar power generator

Abstract: PURPOSE:To utilize midnight power, and to relax the fluctuation of system receiving power by installing a solar cell, a battery and an AC converter and controlling system receiving power in responce to the time, the residue of the battery and the quantity of load of the previous day. CONSTITUTION:In a device in which a solar cell and a battery are connected to a system and load through an inverter, charging (the inverter is used at a converter mode) to the battery from the system and feed to load from the battery are controlled with the time and the residue of the battery. Load is supplied with power from the solar cell and the battery is charged with excess power during the daytime. The battery is discharged and load is supplied with electric power in the mornig and evening. The variation of the quantity of load of the previous day is stored beforehand and the battery is charged while controlling receving power (c) from the system so as not to be fluctuated at midnight.

The Survivable Power (SUPER) Subsystem Demonstration program

Abstract: An overview is presented of the Survivable Power (SUPER) Subsystem Demonstration program. The program is discussed in terms of rationale and the need for increased survivability and power levels for satellite solar power subsystems, the technical approaches being investigated on both the component and subsystem levels, and the specific requirements and programmatics. Progress to date is summarized. >

Multiprocessor control of a renewable energy micro-power station

Abstract: The authors describe the real-time energy management of a multigenerator micro-power station which is intended to supply an isolated village in Senegal using wind and solar power. Laboratory studies have led to a complete understanding of the windmill potential in Dakar, of the functioning and optimization of each generator, and of the transfer of available energy to the receptors. The preliminary studies showed that the structure is feasible and reliable. The architecture developed is modular and extensible, with efficiency and maintenance taken into consideration. >

Solar radiation maps for eiidopia

Abstract: Estimates of solar radiation maps for Ethiopia are prepared from measured solar radiation data of 6 sites and estimates from sunshine hour records of 136 sit es. The estimates for the 136 sites are determined from their sunshine hour data using the Angstrom's linear correlation for the inland regions and that of Schuepp's for the coastal regions where ext re me high and low daily sunshine occurs frequently. The 136 sites are classified into the three climatic zones defined by the EMS and suitable regression constants assigned to each site to estimate the global solar radiation level. From t he maps prepared it could be seen that sizable portion of the Country receives on the average a radiation level of about 5500 wh/m2 day-1, thus signifying the solar power potential i.1 the country.

Unconventional Power Sources for Ice Control at Locks and Dams

Abstract: Assessed herein are the feasibilities of using several unconventional power sources for ice control in navigation locks and dams. Included in this assessment are sensible heat from groundwater, solar power, wind power and portable hydroelectric-power sources. Operation of lock and dam installations is made troublesome and risky by ice growth along lock walls and by freezing of gates to ice covers. Considerable amounts of power are required for force ice control, and, therefore, lock operators are interested in utilizing economical alternative power sources other than that generated by commercial power utilities. However, the present study concludes that of all unconventional power sources, portable hydroelectric-power is the most viable. Groundwater is at best of marginal viability, and solar and wind power sources are unreliable.

Solar radiation maps fot Ethiopia

Abstract: Estimates of solar radiation maps for Ethiopia are prepared from measured solar radiation data of 6 sites and estimates from sunshine hour records of 136 sites. The estimates for the 136 sites are determined from their sunshine hour data using the Angstrom's linear correlation for the inland regions and that of Schuepp's for the coastal regions where ext reme high and low daily sunshine occurs frequently. The 136 sites are classified into the three climatic zones defined by the EMS and suitable regression constants assigned to each site to estimate the global solar radiation level. From the maps prepared it could be seen that sizable portion of the Country receives on the average a radiation level of about 5500 wh/m2 day-1, thus signifying the solar power potential i.1 the country.

Estimated performance and future potential of solar dynamic and photovoltaic power systems for selected LEO and HEO missions

Abstract: Solar photovoltaic and thermal dynamic power systems for application to selected low-earth-orbit (LEO) and high-earth-orbit (HEO) missions are characterized in the regime 7 to 35 kWe. Input parameters to the characterization are varied to correspond to anticipated introduction of improved or new technologies. A comparative assessment is made of the two power system types for emerging technologies in cells and arrays, energy storage, optical surfaces, heat engines, thermal energy storage and thermal management. The assessment is made to common ground rules and assumptions. The four missions (space station, sun-synchronous, Van Allen belt and geosynchronous earth orbit) are presentative of the anticipated range of multikilowatt earth-orbit missions. The results give the expected performance, mass and drag of multikilowatt earth-orbiting solar power systems and show how the overall system figure of merit will improve as new component technologies are incorporated. >

Utilizing the solar energy resources of the eastern and high-latitude regions of the ussr

Abstract: A general exploratory article surveys the solar energy potential of the eastern and northern USSR, an area which the author contends is largely ignored in current Soviet solar energy research. He argues that solar power is a reliable substitute for conventional energy generation in locations remote from major energy grids and where demand is too small to warrant large-capacity conventional units. This argument is based largely upon comparison of insolation characteristics between (a) eastern and high-latitude sites in the USSR with (b) a middle-latitude site (presumably Alushta in the Crimea), and upon examination of the experience in other high-latitude areas (translated by Jay K. Mitchell, PlanEcon, Inc., Washington, DC 20005).

IR radiation transfer from the earth

Abstract: The irradiance at an earth satellite platform due to electromagnetic radiation emitted by the earth is considered as a possible source of energy for electrical power conversion. For low earth-orbiting satellites, the potential exits to compete favorably with conventional solar power.

Evaluation of Performance of the 1 MW Ceramic Tube Receiver at the Weizmann Institute of Science

Abstract: Simulations were performed to evaluate the performance of a subsystem of the Thermochemical Pipeline Project (WITP) of the Weizmann Institute of Science. This subsystem includes a compressor, a 41 m long pipe, a cavity-type central receiver, and a mass-flow control element. The results show that the solar energy available for absorption into the tubes amounts to 1884 MWh/year, under the assumption that the working fluid (air) enters the cavity at 300 K and leaves at 1200 K. For bright days conditions, the average efficiency of the system increases from 56% (at 7 A.M. ) to 69% (at midday), with a yearly average efficiency of 63%. The mass flow is represented by the correlation: where FM is the total mass flow rate of the working fluid (kg/s(, and Ein is the total solar energy entering into the cavity (MW). It is suggested to increase the performance of the receiver by: 1) exploiting a part of the solar power flux existing as spillage, and 2) capturing the energy of the hot air otherwise dissipated by conve...

Control method of solar photovoltaic power generating system

Abstract: PURPOSE:To estimate variation of output from a generating system and to stabilize a power system, by measuring the amount of solar power generated in previous day and controlling the output from an inverter to be proportional to the measured value. CONSTITUTION:In a generating system provided with solar cells 1 and an inverter 3 for converting generated power into AC power and feeding to a commercial power system 4, daily power generation of the solar cells 1 is measured. The inverter 3 is controlled through a controller 6 to produce an output which is proportional to the power generated in previous day. By such arrangement, variation of output can be estimated even in a small scale distributed solar generating system, and hence the system 4 can be stabilized.

Output control method for solar power generator

Abstract: PURPOSE:To reduce the current consumption of a storage battery, by supplying a load and said battery with the output of a solar battery via an electromagnetic switch having a normally closed contact and by opening said electromagnetic switch through said output of the solar battery, when the storage battery is charged fully. CONSTITUTION:The output of solar batteries 1-1, 1-2 is supplied to a load 9 via reverse current blocking diodes 2-1, 2-2 and electromagnetic switches 3-1, 3-2 having normally closed contacts to charge a storage battery 4. When a charging-state detection relay 5 detects a full charging, normally opened contacts 5-1, 5-2 of an electromagnetic switch operating circuit 6 are closed. The output of said solar batteries 1-1, 1-2 is supplied to a D/D converter 7 via reverse current blocking diodes 8-1, 8-2 to energize electromagnetic switch operating coils 3-1a, 3-2a to open normally closed contacts 3-1, 3-2. Thus, the driving current of said electromagnetic switch operating circuit 6 is supplied from the solar batteries to reduce the power consumption of said storage battery.