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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.

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At least 1,423 records · Page 79
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Consensus-Based Control and Optimization of Power System Inertia

The integration of distributed energy resources (DERs), such as solar, wind, and energy storage systems, into power grids through inverter-based resources reduces power system inertia, leading to faster frequency dynamics and potential grid instability. To address this challenge, this paper proposes a distributed, consensus-based approach for the real-time control and optimization of inertia sources (synchronous generators and/or DERs) during system disturbances, enhancing both system stability and economic performance. The distributed control and optimization approach assumes each inertia source exchanges information solely with its neighbor ones, making it easily scalable to large power grid networks. The impacts of the communication connectivity among the inertia sources as well as their generation capacity limits on the distributed approach are investigated. We also demonstrate the approach’s robustness in scenarios involving communication time delays and packet losses, validating its effectiveness through numerical simulations on a 4-bus test system and a two-area 8-bus test system.

Power system inertia↗
DOE OSTI2015

A Serially-Connected Compensator for Eliminating the Unbalanced Three-Phase Voltage Impact on Wind Turbine Generators

Untransposed transmission lines, unbalanced tap changer operations, and unbalanced loading in weak distribution lines can cause unbalanced-voltage conditions. The resulting unbalanced voltage at the point of interconnection affects proper gird integration and reduces the lifetime of wind turbines due to power oscillations, torque pulsations, mechanical stresses, energy losses, and uneven and overheating of the generator stator winding. This work investigates the dynamic impact of unbalanced voltage on the mechanical and electrical components of integrated Fatigue, Aerodynamics, Structures, and Turbulence (FAST) wind turbine generation systems (WTGs) of Type 1 (squirrel-cage induction generator) and Type 3 (doubly-fed induction generator). To alleviate this impact, a serially-connected compensator for a three-phase power line is proposed to balance the wind turbine-side voltage. Dynamic simulation studies are conducted in MATLAB/Simulink to compare the responses of these two types of wind turbine models under normal and unbalanced-voltage operation conditions and demonstrate the effectiveness of the proposed compensator.

17 WIND ENERGY↗
DOE OSTI2024

Rural Hybrid Generation & Microgrids: National Labs are Here to Help

Hear about the tools and technical assistance National Labs can offer to co-ops and other rural utilities seeking to build or enhance hybrid generation projects combining multiple technologies including wind, solar, battery storage, and others resources. These hybrids can deliver additional value by combining complimentary resources and by increasing reliability and resilience, including as part of a microgrid to serve a local load or community. Experienced cooperative and lab experts will share their perspectives on the opportunities there are to make use of their advanced modeling capabilities and expertise to scope, design, and implement these emerging hybrid solutions. Key takeaways for participants will include better understanding of the resilience benefits distributed hybrid systems provide, awareness of National Laboratory assistance programs and resources, tips for successful federal funding applications for these types of projects, and peer-to-peer learning through shared experiences and discussion.

14 SOLAR ENERGY↗
DOE OSTI2013

Dust scattering and the radiation pressure force in the M82 superwind

Radiation pressure on dust grains may be an important physical mechanism driving galaxy-wide superwinds in rapidly star-forming galaxies. We calculate the combined dust and gas Eddington ratio (Γ) for the archetypal superwind of M82. By combining archival Galaxy Evolution Explorer data, a standard dust model, Monte Carlo dust scattering calculations, and the Herschel map of the dust surface density distribution, the observed far-UV/near-UV surface brightness in the outflow constrains both the total UV luminosity escaping from the starburst along its minor axis (L {sub *,UV}) and the flux-mean opacity, thus allowing a calculation of Γ. We find that L {sub *,UV} ≈ (1-6) × 10{sup 42} erg s{sup –1}, ∼2-12 times greater than the UV luminosity observed from our line of sight. On a scale of 1-3 kpc above the plane of M82, we find that Γ ∼ 0.01-0.06. On smaller scales (∼0.25-0.5 kpc), where the enclosed mass decreases, our calculation of L {sub *,UV} implies that Γ ∼ 0.1 with factor of few uncertainties. Within the starburst itself, we estimate the single-scattering Eddington ratio to be of order unity. Thus, although radiation pressure is weak compared to gravity on kpc scales above the plane of M82, it may yet be important in launching the observed outflow. We discuss the primary uncertainties in our calculation, the sensitivity of Γ to the dust grain size distribution, and the time evolution of the wind following M82's recent starburst episodes.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1972

Heat transfer distributions on the LMSC 040C and 040A-L4 delta wing orbiters (M equals 8)7

The results of a wind tunnel investigation are presented for measuring aerodynamic heat transfer distributions on the 040C and 040A-L4 space shuttle orbiter configurations. Heat transfer rates were determined by the phase change coating technique, using 0.012-scale Stycast models coated with Tempilaq. Data were obtained at a nominal free stream Mach number of 8, Reynolds numbers from 1.0 to 3.8 million per foot, and angles of attack from 20 to 60 deg.

Baker, R. C.↗
DOE OSTI2020

Induced Markov chain for wind farm generation forecasting

Systems and methods for forecasting power generation in a wind farm are disclosed. The systems and methods utilize an induced Markov chain model to generate a forecast of power generation of the wind farm. The forecast is at least one of a point forecast or a distributional forecast. Additionally, the systems and methods modify at least one of: (i) a generation of electricity at a power plant coupled to a common power grid as the wind farm; or (ii) a distribution of electricity in the common power grid based on the forecast of power generation of the wind farm. In an exemplary approach, utilizing the induced Markov chain model to generate the forecast may include determining a series of time adjacent power output measurements based on historical wind power measurements and calculating a time series of difference values based on the series of time adjacent power output measurements.

17 WIND ENERGY↗
NASA NTRS1989

Evolution of an unstable shell distribution of pickup cometary ions

Consideration is given to the shell distribution formed by pickup ions in the solar wind. Numerical simulations are used to study the linear and nonlinear development of the waves and the evolution of the initial shell distribution. The linear theory is generalized to include additional effects. It is shown that unstable hydromagnetic fluctuations give rise to diffusion in velocity space and thickening of the shell distribution.

Yoon, Peter H.↗
NASA NTRS2006

Revised Atmospheric Angular Momentum Series Related to Earth's Variable Rotation under Consideration of Surface Topography

The atmospheric angular momentum is closely related to variations in the Earth rotation. The atmospheric excitation function (AEF), or namely atmospheric effective angular momentum function, is introduced in studying the atmospheric excitation of the Earth's variable rotation. It may be separated into two portions, i.e, the "wind" terms due to the atmospheric motion relative to the mantle and the "pressure" terms due to the variations of atmospheric mass distribution evident through surface pressure changes. The AEF wind terms during the period of 1948-2004 are re-processed from the NCEP/NCAR (National Centers for Environmental Prediction-National Center for Atmospheric Research) reanalysis 6-hourly wind and pressure fields. Some previous calculations were approximate, in that the wind terms were integrated from an isobaric lower boundary of 1000 hPa. To consider the surface topography effect, however, the AEF is computed by integration using the winds from the Earth's surface to 10 hPa, the top atmospheric model level, instead of from 1000 hPa. For these two cases, only a minor difference, equivalent to approx. 0.004 milliseconds in length-of-day variation, exists with respect to the axial wind term. However, considerable differences, equivalent to 5-6 milliarcseconds in polar motion, are found regarding equatorial wind terms. We further compare the total equatorial AEF (with and without the topographic effect) with the polar motion excitation function (PMEF) during the period of 1980-2003. The equatorial AEF gets generally closer to the PMEF, and improved coherences are found between them when the topography effect is included. Keywords: Atmospheric angular momentum, Atmospheric excitation function, Earth rotation, Topography, Wind, Pressure.

Zhou, Y. H.↗
DOE OSTI2025

Real-Time Testbed for Smart Grid Recloser Controller

The growing need for a low voltage recloser has become apparent due to the rise in requirements for a smart grid. This includes more detailed management of power flow forward (towards load) and backward (towards generation), source synchronization in real time, more indepth fault responses, and the use of green energy. The SEL-651R-2 relay is a device that can manage these needs, especially in fault response and synchronization, and is commonly used in systems called microgrids. Microgrids are distribution level systems that are able to operate separated from the main grid, are typically installed much closer to the load(s), and are fed by distributed energy resources (DERs), such as wind, solar or diesel generators. The SEL-651R-2 is normally used in the field with presets operative settings, but the Western Michigan University (WMU) Center for Interdisciplinary Research on Secure, Efficient and Sustainable Energy Technology (WMU InterEnergy Center) wished to test this device in its range of capabilities for microgrid application. A Hardware-In-the-Loop (HIL) testbed was implemented and used through the Real Time Digital Simulator (RTDS) using the RSCAD software to test the SEL-651R-2's use cases and functions. The testbed includes a microgrid with interconnection to a larger main grid, and the relay is meant to control the recloser at the point of common coupling (PCC) between the main grid and microgrid. The testbed shows how basic protections, reclosing, and synchronization checks function when handling faults that affect both the microgrid and the main grid.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS1994

Modeling of the coupled magnetospheric and neutral wind dynamos

This report summarizes the progress made in the first year of NASA Grant No. NAGW-3508 entitled 'Modeling of the Coupled Magnetospheric and Neutral Wind Dynamos.' The approach taken has been to impose magnetospheric boundary conditions with either pure voltage or current characteristics and solve the neutral wind dynamo equation under these conditions. The imposed boundary conditions determine whether the neutral wind dynamo will contribute to the high-latitude current system or the electric potential. The semi-annual technical report, dated December 15, 1993, provides further detail describing the scientific and numerical approach of the project. The numerical development has progressed and the dynamo solution for the case when the magnetosphere acts as a voltage source has been evaluated completely using spectral techniques. The simulation provides the field-aligned current distribution at high latitudes due to the neutral wind dynamo. A number of geophysical conditions can be simulated to evaluate the importance of the neutral wind dynamo contribution to the field-aligned current system. On average, field-aligned currents generated by the neutral wind dynamo contributed as much as 30 percent to the large-scale field-aligned current system driven by the magnetosphere. A term analysis of the high-latitude neutral wind dynamo equation describing the field aligned current distribution has also been developed to illustrate the important contributing factors involved in the process. The case describing the neutral dynamo response for a magnetosphere acting as a pure current generator requires the existing spectral code to be extended to a pseudo-spectral method and is currently under development.

Thayer, Jeffrey P.↗
NASA NTRS2012

Solar Wind Electron Interaction with the Dayside Lunar Surface and Crustal Magnetic Fields: Evidence for Precursor Effects

Electron distributions measured by Lunar Prospector above the dayside lunar surface in the solar wind often have an energy dependent loss cone, inconsistent with adiabatic magnetic reflection. Energy dependent reflection suggests the presence of downward parallel electric fields below the spacecraft, possibly indicating the presence of a standing electrostatic structure. Many electron distributions contain apparent low energy (<100 eV) upwardgoing conics (58% of the time) and beams (12% of the time), primarily in regions with non-zero crustal magnetic fields, implying the presence of parallel electric fields and/or wave-particle interactions below the spacecraft. Some, but not all, of the observed energy dependence comes from the energy gained during reflection from a moving obstacle; correctly characterizing electron reflection requires the use of the proper reference frame. Nonadiabatic reflection may also play a role, but cannot fully explain observations. In cases with upward-going beams, we observe partial isotropization of incoming solar wind electrons, possibly indicating streaming and/or whistler instabilities. The Moon may therefore influence solar wind plasma well upstream from its surface. Magnetic anomaly interactions and/or non-monotonic near surface potentials provide the most likely candidates to produce the observed precursor effects, which may help ensure quasi-neutrality upstream from the Moon.

Solar↗
DOE OSTI2012

The Impact of Wind Development on County-Level Income and Employment: A Review of Methods and an Empirical Analysis (Fact Sheet). Wind And Water Power Program (WWPP).

The economic development potential from wind power installations has been a driver of public and policy support for the industry at the local and state levels for many years. The possibility for economic development has been particularly salient in rural areas of the country where new investment, earnings growth, and employment opportunities have, in many cases, otherwise trended downward for some time. Despite frequent mention of the economic development potential of wind power projects, however, questions persist on the magnitude, distribution, and durability of these impacts. Of particular concern for rural communities is whether new investment in wind power projects stimulates long-term local economic growth and employment. Questions about the economic development and employment impacts of wind power also persist at the national level. However, such debates tend to be more concerned with potential economic losses associated with displacement of other energy sources or land uses and the macroeconomic effects of policy support for renewable energy and changes in electricity rates that might result from wind energy deployment. The present analysis focuses solely on county-level impacts.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
NASA NTRS1972

Evaluation of Skylab IB sensitivity to on-pad winds with turbulence

Computer simulation was performed to estimate displacements and bending moments experienced by the SKYLAB 1B vehicle on the launch pad due to atmospheric winds. The vehicle was assumed to be a beam-like structure represented by a finite number of generalized coordinates. Wind flow across the vehicle was treated as a nonhomogeneous, stationary random process. Response computations were performed by the assumption of simple strip theory and application of generalized harmonic analysis. Displacement and bending moment statistics were obtained for six vehicle propellant loading conditions and four representative reference wind profile and turbulence levels. Means, variances and probability distributions are presented graphically for each case. A separate analysis was performed to indicate the influence of wind gradient variations on vehicle response statistics.

Coffin, T.↗
NASA NTRS1945

A Systematic Investigation of Pressure Distributions at High Speeds over Five Representative NACA Low-Drag and Conventional Airfoil Sections

Pressure distributions determined from high-speed wind-tunnel tests are presented for five NACA airfoil sections representative of both low-drag and conventional types. Section characteristics of lift, drag, and quarter-chord pitching moment are presented along with the measured pressure distributions for the NACA 65sub2-215 (a=0.5), 66sub2-215 (a=0.6), 0015, 23015, and 4415 airfoils for Mach numbers up to approximately 0.85. A critical study is made of the airfoil pressure distributions in an attempt to formulate a set of general criteria for defining the character of high speed flows over typical airfoil shapes. Comparisons are made of the relative characteristics of the low-drag and conventional airfoils investigated insofar as they would influence the high-speed performance and the high-speed stability and control characteristics of airplanes employing these wing sections.

Graham, Donald J↗
DOE OSTI2017

Impact of baryonic physics on intrinsic alignments

We explore the effects of specific assumptions in the subgrid models of star formation and stellar and AGN feedback on intrinsic alignments of galaxies in cosmological simulations of "MassiveBlack-II" family. Using smaller volume simulations, we explored the parameter space of the subgrid star formation and feedback model and found remarkable robustness of the observable statistical measures to the details of subgrid physics. The one observational probe most sensitive to modeling details is the distribution of misalignment angles. We hypothesize that the amount of angular momentum carried away by the galactic wind is the primary physical quantity that controls the orientation of the stellar distribution. Finally, our results are also consistent with a similar study by the EAGLE simulation team.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1998

Vertical Distribution of Saharan Dust from the Goddard Three Dimensional Transport Model: Comparison with LITE Data

Spatial distributions of Saharan dust are simulated by the Goddard 3D chemistry transport model driven by meteorological fields from the Goddard Earth Observing System Data Assimilation System, GEOS-2 DAS. An aerosol module accounts for gravitational settling and the aerosol source function is based on surface moisture content and wind speed. The simulated aerosol fields are compared with Total Ozone Mapping Spectrometer (TOMS) by P. Ginoux in this session. The main focus is how ventilation of the assimilation winds will impact the simulated aerosol vertical distribution. Excessive ventilation would transport too much aerosol in the upper troposphere and lead to errors in the long range transport as well as errors in any radiative forcing calculations derived from the simulated aerosol fields. Simulated aerosol fields using GEOS-1 DAS wind fields for September 1994 will be compared with lidar observations during the Lidar In-space Technology Experiment (LITE). The lidar return signal clearly delineates the vertical extent and horizontal variability of the aerosol layer allowing rigorous comparison with the simulated fields. A second focus is the simulation of aerosol scavenging due to moist processes. Three-dimensional precipitation fields can be derived from two possible sources: Assimilated precipitation fields from GEOS-DAS or fields obtained from the Special Sensor Microwave/imager (SSM/1). Of interest is the sensitivity of the modeled aerosol fields to the different precipitation fields driving the moist scavenging module.

Weaver, Clark J.↗
DOE OSTI2013

Correlations at large scales and the onset of turbulence in the fast solar wind

We show that the scaling of structure functions of magnetic and velocity fields in a mostly highly Alfvénic fast solar wind stream depends strongly on the joint distribution of the dimensionless measures of cross helicity and residual energy. Already at very low frequencies, fluctuations that are both more balanced (cross helicity ∼0) and equipartitioned (residual energy ∼0) have steep structure functions reminiscent of 'turbulent' scalings usually associated with the inertial range. Fluctuations that are magnetically dominated (residual energy ∼–1), and so have closely anti-aligned Elsasser-field vectors, or are imbalanced (cross helicity ∼1), and so have closely aligned magnetic and velocity vectors, have wide '1/f' ranges typical of fast solar wind. We conclude that the strength of nonlinear interactions of individual fluctuations within a stream, diagnosed by the degree of correlation in direction and magnitude of magnetic and velocity fluctuations, determines the extent of the 1/f region observed, and thus the onset scale for the turbulent cascade.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2021

Electron Bernstein waves and narrow band plasma waves near the electron cyclotron frequency in the near-Sun solar wind

Context. Recent studies of the solar wind sunward of 0.25 AU reveal that it contains quiescent regions, with low-amplitude plasma and magnetic field fluctuations, and a magnetic field direction similar to the Parker spiral. The quiescent regions are thought to have a more direct magnetic connection to the solar corona than other types of solar wind, suggesting that waves or instabilities in the quiescent regions are indicative of the early evolution of the solar wind as it escapes the corona. The quiescent solar wind regions are highly unstable to the formation of plasma waves near the electron cyclotron frequency (fce). Aims. We examine high time resolution observations of these waves in an effort to understand their impact on electron distribution functions of the quiescent near-Sun solar wind. Methods. High time resolution waveform captures of near-fce waves were examined to determine variations of their amplitude and frequency in time as well as their polarization properties. Results. We demonstrate that the near-fce wave intervals contain several distinct wave types, including electron Bernstein waves and extremely narrowband waves that are highly sensitive to the ambient magnetic field orientation. Using the properties of these waves, we suggest possible plasma wave mode classifications and possible instabilities that generate these waves. The results of this analysis indicate that these waves may modify the cold core of the electron distribution functions in the quiescent near-Sun solar wind.

David M. Malaspina↗