Search NASA⌕ Search

SEARCH · Search NASA

Results for “Distributed Solar”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Design and performance of the solar maximum mission Hard X-ray Burst Spectrometer

The Hard X-ray Burst Spectrometer acquires data on the temporal and energy distribution of solar X-rays in the energy region from 25 to 385 keV. The detector system is a CsI(Na) central detector, and an anti-coincidence shield with photomultiplier tubes optically coupled to the central and shield crystals. Additional detectors are included for calibration and South Atlantic Anomaly monitoring. A 15 channel pulse height analysis is performed over the energy range every 128 milliseconds. This instrument is capable of handling event rates up to 500 kHz and provides high rate data up to 100 kHz with low spectral distortion. Nine accumulated rates are telemetered every 8.192 seconds. A unique feature of the instrument is the ability to sample rates from the central detector or shield with a one millisecond minimum time resolution. Such samples are stored in a 32768 sample memory with a 40 percent pretrigger event history and a 60 percent posttrigger history.

Workman, L. G.↗
DOE OSTI2024

Convolution Neural Network for Fault Identification in Distribution Feeder with High Penetration Solar PV

Identification and zonal classification of the faults is a decisive factor in the relay’s decision to trip or not. Different types of fault like three-phase, line-to-line-to-ground and single-line-to-ground can occur at various locations in the feeder. These faults are seen as the variation in the instantaneous values of three-phase voltages and currents, i.e., waveforms, that are measured at the relay location. The objective of this work is to develop a machine learning model that can identify a fault and classify it to various protection zones based on measured waveforms. In this work, a data-driven relay based on Convolutional Neural Network (CNN) is proposed for fault identification in distribution feeders with high penetration solar PV. The proposed CNN model takes local current and voltage waveforms as input and classify it into fault, no-fault or a capacitor switching. Further, the CNN also attempts to identify fault zones based on the images of waveforms. The overall testing accuracy of the trained model exceeds 95%.

Ramesh, Meghana↗
DOE OSTI2022

Getting to 95

Members of the Tennessee Valley Public Power Association (TVPPA) have the opportunity to interconnect up to 5% of their annual energy requirements in self generation. TVA, their wholesale supplier, is encouraging solar. This presentation introduces IEEE 1547 2018 and provides some high level information on solar cost.

DER↗
NASA NTRS1993

Velocity distributions of hydrogen atoms and hydroxyl radicals produced through solar photodissociation of water

The velocity distributions of H and OH fragments produced through solar photodissociation of gaseous H2O molecules under collisionless conditions are presented. The calculations are carried out using: the most recently available absolute partial cross sections for the production of H and OH through photodissociation of H2O from its absorption onset at 1860 A down to 500 A; the newly available vibrational and rotational energy distributions of both the excited and ground state OH photofragments; the calculated cross sections for the total dissociation processes; and the integrated solar flux in 10 A increments from 500 to 1860 A in the continuum regions and the specific wavelength and flux at the bright solar lines. The calculated results show that the H atoms and the OH radicals produced exhibit multiple velocity groups. Since most current cometary modeling uses a single velocity of 20 km/sec associated with the photodissociation of H2O, the present results may be useful in interpreting the many peaks observed in the velocity distributions of the H Lyman alpha and H alpha of comets.

Wu, C. Y. R.↗
NASA NTRS1980

The dish-Rankine SCSTPE program (Engineering Experiment no. 1)

Activities planned for phase 2 Of the Small Community Solar Thermal Power Experiment (PFDR) program are summarized with emphasis on a dish-Rankine point focusing distributed receiver solar thermal electric system. Major design efforts include: (1) development of an advanced concept indirect-heated receiver;(2) development of hardware and software for a totally unmanned power plant control system; (3) implementation of a hybrid digital simulator which will validate plant operation prior to field testing; and (4) the acquisition of an efficient organic Rankine cycle power conversion unit. Preliminary performance analyses indicate that a mass-produced dish-Rankine PFDR system is potentially capable of producing electricity at a levelized busbar energy cost of 60 to 70 mills per KWh and with a capital cost of about $1300 per KW.

Pons, R. L.↗
NASA NTRS1999

Optical Evaluation of a Refractive Secondary Concentrator

Refractive secondary concentrators are being considered for solar thermal applications because of their ability to archive maximum efficiency through the use of total internal reflection for the concentration and distribution of solar energy. A prototype refractive secondary concentrator was built based on ray tracing analysis to demonstrate this collection and distribution concept. The design included a conical secondary concentrator and a faceted extractor. The objective of this effort was to functionally evaluate the performance of the refractive secondary concentrator/extractor prototype and to compare the results with modeling. Most of the light was found to exit the refractive secondary concentrator through the extractor. In addition, the degree of attenuation encountered by the light as it passed through the refractive secondary concentrator was of interest. Quantifying optical output and validating the modeling will provide further understanding of the efficiency of the prototype and will provide insight for additional design and materials selection activities.

Jaworske, Donald A.↗
DOE OSTI2023

Risk-Informed Condition Evaluation of Solar-centered Energy Generation and Distribution Networks through Bayesian Learning and Inference

We develop a methodology based on Bayesian inference over Probabilistic Graphical Models (PGMs) to understand and quantify risk in solar-centered grids using targeted measurements and learned system behavior. Being non-prescriptive but, rather, able to infer system behavior and, ultimately, address risk queries from data, our machine learning-type paradigm is tailored for diverse topologies and threat scenarios often associated with distributed energy generation and photovoltaic distributed energy resources (PV-DERs) in particular. We describe algorithmic processes for: (i) learning the structure of PGMs that result from attack-prone PV-DER-proliferated distribution systems, (ii) quantifying cause-effect relationships, and (iii) evaluating risk queries based on diverse evidence. The contributions are illustrated on a residential grid subject to output impairment attacks on its PV-DER infrastructure.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS1994

Solar wind contribution to the average population of energetic He(+) and He(++) ions in the Earth's magnetosphere

Measurements with the ion charge-energy-mass spectrometer CHEM on the AMPTE/CCE spacecraft were used to investigate the origin of energetic He(+) and He(++) ions observed in the equatorial plane at 3 less than or equal to L less than or equal to 9. Special emphasis was laid on the dependence of long-term average distributions on magnetic local time (MLT) and the geomagnetic activity index K(sup p). The observations are described in terms of the phase space densities f(sub 1) (for He(+)) and f(sub 2) (for He(++)). They confirm preliminary results from a previous study f(sub 1) is independent of MLT, whereas f(sub 2) is much larger on the nightside than on the dayside. They show, furthermore, that f(sub 1) increases slightly with K(sub p) on intermediate drift shells, but decreases on high drift shells (L greater than or equal to 7). f(sub 2) increases with K(sub p) on all drift shells outside the premidnight sector. Within this sector a decrease is observed on high drift shells. A simple ion tracing code was developed to determine how and from where the ions move into the region of observations. It provides ion trajectories as a function of the ion charge, the magnetic moment and K(sub p). The ion tracing enables a distinction between regions of closed drift orbits (ring current) and open convection trajectories (plasma sheet). It also indicates how the outer part of the observation region is connected to different parts of the more distant plasma sheet. Observations and tracing show that He(++) ions are effectively transported from the plasma sheet on convection trajectories. Their distribution in the observation region corresponds to the distribution of solar wind ions in the plasma sheet. Thus, energetic He(++) ions most likely originate in the solar wind. On the other hand, the plasma sheet is not an important source of energetic He(+) ions. Convection trajectories more likely constitute a sink for He(+) ions, which may diffuse onto them from closed drift orbits and then get lost through the magnetopause. An ionospheric origin of energetic He(+) ions is unlikely as well, since the source mechanism should be almost independent of K(sub p). There is considerable doubt, however, that a plausible mechanism also exists during quiet periods that can accelerate ions to ring current energies, while extracting them from the ionosphere. It is concluded, therefore, that energetic He(+) ions are mainly produced by charge exchange processes from He(++) ions. This means that most of the energetic He(+) ions constituting the average distributions also very likely originate in the solar wind. Additional ionospheric contributions are possible during disturbed periods.

Kremser, G.↗
NASA NTRS1984

A 154-day periodicity in the occurrence of hard solar flares?

An analysis of the temporal distribution of 139 solar flares monitored by the Gamma Ray Spectrometer aboard the Solar Maximum Mission is reported. It is found that, instead of being randomly distributed in time, these events have a tendency to occur in groups with a mean spacing of about 154 days (75 nHz) over the observing interval. A larger sample of flares with an X-ray classification of M 2.5 or larger recorded by the GOES satellite showed a similar regularity.

Rieger, E.↗
DOE OSTI2024

Adapte Agrivoltayik Pou Mini-Rezo Sole Ann Ayiti

Ak mwens pase 2% nan popilasyon riral la ki gen akse a elektrisite ak preske mwatye popilasyon an ap fe fas ak grangou egi, Ayiti fe fas a defi entekonekte nan povrete eneji ak ensekirite alimante. Yon solisyon pou ede abode povrete eneji ann Ayiti se devlopman mini-griy sole distribiye, sitou sole. Sepandan, souvan te ki pi byen adapte pou deplwaye jenerasyon sole se tou pi byen adapte pou agrikilti pa ti femye yo, kidonk kreye yon tansyon potansyelman konplike ant akse eneji ak sekirite manje. Pou adrese tansyon sa a, devlope sole yo, espesyalis agrikol yo ak cheche yo ap egzamine ansanm yon nouvo solisyon ki rele "agrivoltayik". Agrivoltaics se yon solisyon pataje te-itilize ki rapidman elaji nan mache sole etabli tankou Etazini, Ewop, ak Azi ki pe sole ak agrikilti, pwodwi elektrisite ak bay espas pou rekot ak bet patiraj anba ak ant panno. Nan kad Patenarya Akse Eneji pou Ayiti a ak Ajans Ameriken pou Devlopman Entenasyonal (USAID), Laboratwa Nasyonal Eneji Renouvlab (NREL) te fe yon premye analiz posibilite ak pwoje angajman pati konsene yo pou evalye potansyel agrivoltayik nan konteks mini-gri an Ayiti. Analiz la te konsidere mini-grid tipik 100-kW ak pi gwo 1-MW nan vil atrave Ayiti epi li te devlope de egzanp arketip agrivoltaik ki baze sou kontribisyon lokal kle yo, ki gen ladan irradians sole, done pwodiksyon ki soti nan resansman agrikol la, pri sou mache a, entevyou ak moun ki gen entere yo, ak ki egziste deja, rechech agrivoltayik. See NREL/TP-7A40-88444 for the English translation of this document.

14 SOLAR ENERGY↗
NASA NTRS1995

On the spatial distribution of magnetic fields on the solar surface

Recent measurements of solar surface magnetic fields suggest that the spatial distribution of these fields is fractal. In order to understand the physical basis for such geometric complexity, we study here the advection of magnetic flux tubes relatively simple random motions on the surface of a fluid and investigate the spatial statistics of the resulting surface field. While this study does not directly address the question of why solar surface fields have the observed spatial structure, it is designed to build our intuition about how surface flows lead to complex spatial structuring of magnetic fields. As part of our study, we discuss the various methods by which one can describe the spatial distribution of the surface magnetic flux and relate them mathematically; this turns out to be a crucial point of our work since, as we show, a number of previous analyses have misinterpreted the analysis procedures for determining fractal dimensions. Our principal result is the explicit demonstration that simple random flows lead to magnetic flux spatial distributions with a multifractal dimension spectrum. Furthermore, we demonstrate that this magnetic spatial structure is generic, i.e., is characteristic of a very large class of random flows.

Tao, L.↗
NASA NTRS1983

Radial evolution of ion distribution functions

A survey of solar wind ion velocity distributions and derived parameters (temperature, ion differential speed, heat flux, adiabatic invariants) is presented with emphasis on the heliocentric distance range between 0.3 and 1 AU traversed by the Helios solar probe. The radial evolution of nonthermal features are discussed which are observed to be most pronounced at perihelion. Within the framework of quasilinear plasma theory, wave particle interactions that may shape the ion distributions are considered. Some results of a self consistent model calculation are presented accounting for ion acceleration and heating by resonant momentum and energy exchange with ion cyclotron and magnetosonic waves propagating away from the Sun along the interplanetary magnetic field. Another tentative explanation for the occurrence of large perpendicular proton temperatures is offered in terms of heating by Landau damping of lower hybrid waves.

Marsch, E.↗
DOE OSTI2019

Design, characterization, and fabrication of solar-retroreflective cool-wall materials

Raising urban albedo increases the fraction of incident sunlight returned to outer space, cooling cities and their buildings. We evaluated the angular distribution of solar radiation incident on exterior walls in 17 U S. climates to develop performance parameters for solar-retroreflective walls, then applied first-principle physics and ray-tracing simulations to explore designs. Our analysis indicates that retroreflective walls must function at large incidence angles to reflect a substantial portion of summer sunlight, and that this will be difficult to attain with materials that rely on total internal reflection. Gonio-spectrophotometer measurements of the solar spectral bi-directional reflectivity of a bicycle reflector showed little to no retroreflection at large incidence angles. Visual comparisons of retroreflection to specular first-surface reflection for four different retroreflective safety films using violet and green lasers suggest their retroreflection to be no greater than 0.09 at incidence angles up to 45°, and no greater than 0.30 at incidence angles of up to 70°. Attempts to produce a two-surface retroreflector with orthogonal mirror grooves by cutting and polishing an aluminum block indicate that residual surface roughness impedes retroreflection. Ongoing efforts focus on forming orthogonal surfaces with aluminized Mylar film, a material with very high specular reflectance across the solar spectrum. We investigated (1) folding or stamping a free film; (2) adhering the film to a pre-shaped substrate; or (3) attaching the film to a flat ductile substrate, then shaping. The latter two methods were more successful but yielded imperfect right angles.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗