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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 1,135 records · Page 63
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Load Modeling with Smart Meter Data for Advanced Volt-VAR Optimization Applications

This paper demonstrates the creation of time-varying, end-use electric load models with electric meter data for use by advanced, model-based volt-VAR optimization (VVO) control schemes. VVO has been shown to reduce energy consumption and peak demand in the electric distribution system. Modern VVO systems use power flow models to make control decisions. In order to make optimal decisions, these models must contain accurate load models. To improve these load models, this work uses active power, reactive power, and voltage magnitude measurements from advanced metering infrastructure (AMI) in a simulated distribution feeder to create electric load models for each customer meter. Three different modeling approaches are discussed, and their effectiveness is measured by comparing the optimality of VVO solutions with a base case. The results show that the models derived from AMI data can accurately represent some end-use load behavior like total energy costs, but lose accuracy when considering more dynamic system behavior like voltage violations over small time intervals. This work helps to advance state-of-the-art, model-based VVO by providing a data-driven modeling technique which acknowledges that optimal distribution system control requires a treatment of the system which is dependent on time, voltage, and system conditions.

Thayer, Brandon L.↗
DOE OSTI2020

The Effect of Power Electronic Loads on Western Interconnection Stability

The prevalence of power electronics in the bulk power system is increasing rapidly in both the generation and consumption of electricity. This work focuses on the effect of changing load composition - specifically the transition from single phase air conditioner motors to power electronics backed air conditioners - on power system stability. Various transmission and generation contingency events for the Western Interconnection were simulated using Positive Sequence Load Flow software and planning models from the Western Electricity Coordinating Council. In general, an increased proportion of power electronic load leads to more instability. For some specific faults resulting in fault-induced delayed voltage recovery, transitioning to higher proportions of power electronic loads helps expedite system recovery. These results demonstrate that load composition should be examined in conjunction with generation composition when evaluating system stability.

FIDVR↗
DOE OSTI2021

A Load Switching Group based Feeder-level Microgrid Energy Management Algorithm for Service Restoration in Power Distribution System

This paper presents a load switching group based energy management system (LSG-EMS) for operating microgrids on a distribution feeder powered by one or multiple grid-forming distributed energy resources. Loads on a distribution feeder are divided into load switching groups that can be remotely switched on and off. The LSG-EMS algorithm, formulated as a mixed-integer linear programming (MILP) problem, has an objective function of maximizing the served loads while minimizing the total number of switching actions. A new set of topology constraints are developed for allowing multiple microgrids to be formed on the feeder and selecting the optimal supply path. Customer comfort is accounted for by maximizing the supply duration in the customer preferred service period and enforcing a minimum service duration. The proposed method is demonstrated on a modified IEEE 33-bus system using actual customer data. Simulation results show that the LSG-EMS successfully coordinates multiple grid-forming sources by selecting an optimal supply topology that maximizes the supply period of both the critical and noncritical loads while minimizing customer service interruptions in the service restoration process.

Hu, Rongxing↗
DOE OSTI2021

Design of Resilient Electric Distribution Systems for Remote Communities: Surgical Load Management using Smart Meters

This paper describes a systematic process of designing resilient electric distribution systems and microgrids using smart meters for surgical load management (SLM) as part of Advanced Metering Infrastructure (AMI). The work focuses on selection approach, integration, and interoperability aspects for AMI in microgrids. SLM is proposed as a granular control methodology for serving selective critical loads across different distribution feeders in the system during extreme events. The surgical load shedding as well as load pick-up provides a robust approach for maximizing critical load served in a resource-constrained electric distribution system or a microgrid. We present the case of a 20 MW islanded microgrid in Cordova, AK, USA, which is the demonstration site for field validation of resilience enhancement technologies for the DOE-funded Grid Modernization project RADIANCE. Cordova microgrid is an islanded distribution grid that provides an environment to prove the approach, and the techniques may also be applicable to other regional distribution systems.

microgrids↗
DOE OSTI2015

Generalized Aggregation and Coordination of Residential Loads in a Smart Community

Flexibility from residential loads presents an enormous potential to provide various services to the smart grid. In this paper, we propose a unified hierarchical framework for aggregation and coordination of various residential loads in a smart community, such as Thermostatically Controlled Loads (TCLs), Distributed Energy Storages (DESs), residential Pool Pumps (PPs), and Electric Vehicles (EVs). A central idea of this framework is a virtual battery model, which provides a simple and intuitive tool to aggregate the flexibility of distributed loads. Moreover, a multi-stage Nash-bargainingbased coordination strategy is proposed to coordinate different aggregations of residential loads for demand response. Case studies are provided to demonstrate the efficacy of our proposed framework and coordination strategy in managing peak power demand in a smart residential community.

Hao, He↗
DOE OSTI2020

Quantifying Load Uncertainty Using Real Smart Meter Data

As we get closer to customers in distribution systems, load stochasticity increases. In the past, due to lack of real-time data, the comprehensive knowledge of load behavior was limited, and simplistic assumptions had to be made for distribution system modeling and analysis, especially in the processes of network design and expansion. With the deployment of Advanced Metering Infrastructure (AMI), ample real-time smart meter data has become available to utilities. In this paper, using real hourly smart meter data, we have quantified load uncertainty in terms of average, maximum and maximum noncoincident demands on a daily basis, as well as load factor and diversity factor. These uncertainty metrics are examined for individual residential, commercial and industrial customers, as well as distribution transformers serving residential customers. This paper provides a benchmark on load uncertainty quantification for practicing engineers and researchers.

Bu, Fankun↗
DOE OSTI2016

Distributed Load Shedding over Directed Communication Networks with Time Delays

When generation is insufficient to support all loads under emergencies, effective and efficient load shedding needs to be deployed in order to maintain the supply-demand balance. This paper presents a distributed load shedding algorithm, which makes efficient decision based on the discovered global information. In the global information discovery process, each load only communicates with its neighboring load via directed communication links possibly with arbitrarily large but bounded time varying communication delays. We propose a novel distributed information discovery algorithm based on ratio consensus. Simulation results are used to validate the proposed method.

Yang, Tao↗
DOE OSTI2018

Regional Assessment of Virtual Battery Potential from Building Loads

Flexibility from building loads can be used for integrating renewable energy and providing different grid services. It is challenging to quantify and compare the flexibility from different classes of building loads due to their diversified characteristics and dynamics. Methodology has been proposed to model building loads as a virtual battery (VB), which is simple and general, yet able to capture physical characteristics of building loads, environmental parameters, human behavior, and other factors. This paper presents a regional assessment of VB technical potential and economic benefits from residential loads and commercial buildings. Housing, population, weather station, and climate zone information have been collected and used to estimate VB technical potential. Energy and ancillary service prices are then used for economic benefits assessment and analysis.

Wu, Di↗
DOE OSTI2019

Data-Driven Load Modeling and Forecasting of Residential Appliances

The expansion of residential demand side management programs and increased deployment of controllable loads require accurate appliance-level load modeling and forecasting. This paper proposes a conditional hidden semi-Markov model to describe the probabilistic nature of residential appliance demand. Model parameters are estimated directly from power consumption data using scalable statistical learning methods. We also propose an algorithm for short-term load forecasting as a key application for appliance-level load models. Case studies performed using granular sub-metered power measurements from various types of appliances demonstrate the effectiveness of the proposed load model for short-term prediction.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2018

Impaired phloem loading in zmsweet13a,b,c sucrose transporter triple knock‐out mutants in Zea mays

Summary Crop yield depends on efficient allocation of sucrose from leaves to seeds. In Arabidopsis, phloem loading is mediated by a combination of SWEET sucrose effluxers and subsequent uptake by SUT 1/ SUC 2 sucrose/H + symporters. Zm SUT 1 is essential for carbon allocation in maize, but the relative contribution to apoplasmic phloem loading and retrieval of sucrose leaking from the translocation path is not known. Here we analysed the contribution of SWEET s to phloem loading in maize. We identified three leaf‐expressed SWEET sucrose transporters as key components of apoplasmic phloem loading in Zea mays L. Zm SWEET 13 paralogues (a, b, c) are among the most highly expressed genes in the leaf vasculature. Genome‐edited triple knock‐out mutants were severely stunted. Photosynthesis of mutants was impaired and leaves accumulated high levels of soluble sugars and starch. RNA ‐seq revealed profound transcriptional deregulation of genes associated with photosynthesis and carbohydrate metabolism. Genome‐wide association study (GWAS) analyses may indicate that variability in Zm SWEET 13s correlates with agronomical traits, especifically flowering time and leaf angle. This work provides support for cooperation of three Zm SWEET 13s with Zm SUT 1 in phloem loading in Z. mays .

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Loads on a Jacket-Supported Wind Turbine During Hurricane Sandy Simulation

Abstract The dynamic response of a jacket-supported offshore wind turbine under coupled wind, wave, and current fields during Hurricane Sandy is the subject of this study. To illustrate the detailed procedure related to the response evaluation of a 5-MW offshore wind turbine with a jacket support structure, we consider a single site where the water depth is 50 m. Loads are computed using two simulation tools, fast and abaqus, with partial coupling. Aerodynamic loads on the turbine rotor are first evaluated using a wind turbine model in fast with a fixed base; then, these rotor aerodynamic loads are applied as point loads at the top of a model of a tower that is supported by a jacket structure in abaqus. On the basis of stochastic simulations, we discuss the applicability of the abaqus jacket modeling and describe the characteristics and comparisons of the aerodynamic and hydrodynamic effects on loads on the jacket members. Details related to the structural model and soil–pile interaction model employed in the analyses are also discussed.

Engineering↗
DOE OSTI2024

Efficient Modeling of Floating Wind Arrays Including Current Loads and Seabed Bathymetry

Capabilities for modeling the effects of seabed bathymetry and current drag loads on a floating wind farm are now available in an open-source model for quasi-static analysis. In this model, mooring lines and dynamic cables are represented by a quasi-static solver that can quickly represent complex mooring/cabling arrangements and arrays of floating bodies. To account for seabed bathymetry, we expand the model to include a surface mesh that captures changes in water depth over a rectangular grid. We formulate modifications to the catenary equations that capture a mooring line's profile and tensions when contacting a slope seabed. To account for current drag loads on mooring lines and dynamic cables, we formulate a novel technique that rotates the reference frame so that the vector sum of the the weight and the current force are used in the catenary equations, while accounting for the seabed orientation. To complete the system, current drag loads on floating substructures are handled by inclusion of strip-theory drag calculations. These new capabilities are verified by comparing with results from the established offshore dynamics models MoorDyn and OrcaFlex in equivalent steady-state scenarios. The results show very good agreement for both sloped seabeds and current loads. With computation times of the quasi-static model typically under one second, the model additions are a useful capability toward rapidly evaluating a floating wind array's response to environmental loads under realistic site conditions.

bathymetry↗
DOE OSTI2022

MECHANICAL PERFORMANCE EVALUATION OF THE PRINTED CIRCUIT HEAT EXCHANGER CORE EXPERIMENTS UNDER TENSION AND PRESSURE LOADING

The printed circuit heat exchanger (PCHE) has small channels with high surface area, making them an efficient solution for next-generation nuclear plants (NGNPs). These PCHEs are fabricated through a diffusion bonding process. This fabrication step changes the microstructure of wrought metal plates. The current ASME design code does not support the PCHE design for NGNPs due to a lack of test data. Hence, there has been initiative towards elevated temperature mechanical property characterization of the diffusion bonded material. One of the most common channel shapes is a semicircular channel with sharp corners. These corners act as a stress riser at the diffusion bonding interface. Evaluating elevated temperature mechanical performance of diffusion bonded material in the presence of stress risers is an essential step towards the ASME code development of PCHE design. This study selected two specimen geometries: the first is a PCHE bar specimen for tensile loading with three rows and three columns of channels, and the second is a lab-scaled PCHE with six rows and eight columns of channels. A set of elevated temperature monotonic and cyclic tests were conducted on the PCHE bar specimen to evaluate the mechanical performance under axial tensile loadings to study the failure mechanism. The lab-scaled PCHE specimens were tested under overpressure loads at room temperature, and pressure creep and pressure creep-fatigue loadings to mimic the realistic loading conditions observed in typical NGNPs. The X-ray scans of channeled specimens show interesting observations. The test results and observations are presented in the paper.

36 MATERIALS SCIENCE↗
DOE OSTI2015

MO-FG-BRA-05: Next Generation Radiotherapy Biomaterials Loaded With Gold Nanoparticles

Purpose: It has been proposed that routinely used inert radiotherapy (RT) biomaterials (e.g. fiducials, spacers) can be upgraded to smarter ones by coating/loading them with radiosensitizing gold nanoparticles (GNPs), for sustained in-situ release after implantation to enhance RT. In this work, we developed prototypes of such RT biomaterials and investigated the sustained release of GNPs from the biomaterials as a function of design parameters. Methods: Prototype smart biomaterials were produced by incorporating the GNPs in poly(D,L-lactide-co-glycolide) (PLGA) polymer millirods during the gel phase of production. For comparison, commercially available spacers were also coated with a polymer film loaded with fluorescent GNP. Optical/spectroscopy methods were used to monitor in vitro release of GNPs over time as a function of different design parameters: polymer weighting, type, and initial (loading) GNP concentrations. Inductively coupled plasma mass spectrometry was employed to verify GNP release. Results: Results showed that gold nanoparticles could be successfully loaded in the new RT biomaterial prototypes. Burst release of GNPs could be achieved within 1 to 25 days depending on the preparation approach. Burst release was followed by sustained release profile over time. The amount of released GNP increased with increasing loading concentration as expected. The release profiles could also be customized as a function of polymer weighting, or preparation approaches. Conclusion: Considered together, our results highlight potential for the development of next generation RT biomaterials loaded with GNPs customizable to different RT schedules. Such biomaterials could be employed as needed instead of currently used inert spacers/fiducials at no additional inconvenience to patients, to enhance RT.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Effect of Zeeman Slower Beam on Loading of a Krypton Magneto-Optical Trap

We report the studies on the effect of Zeeman slower beam power on the loading rate and collision loss rate in an atomic beam loaded krypton magneto-optical trap (MOT). The results show that an increase in Zeeman slower beam power initially increases the MOT loading rate and reduces the background collision loss rate to increase the number of cold atoms in the MOT to an optimum value. With further increase in the Zeeman slower beam power, the number of cold atoms in the MOT decreases due to increased background collision loss rate and decrease in the trap loading rate. However, the cold collision loss rate is observed to remain unaffected by the variation in the Zeeman slower beam power. Therefore, the study emphasizes the need to optimize the Zeeman slower beam power to trap maximum number of cold atoms in an atomic beam loaded MOT.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Carbon-Binder Weight Loading Optimization for Improved Lithium-Ion Battery Rate Capability

Battery performance is strongly correlated with electrode microstructure and weight loading of the electrode components. Among them are the carbon-black and binder additives that enhance effective conductivity and provide mechanical integrity. However, these both reduce effective ionic transport in the electrolyte phase and reduce energy density. Therefore, an optimal additive loading is required to maximize performance, especially for fast charging where ionic transport is essential. Such optimization analysis is however challenging due to the nanoscale imaging limitations that prevent characterizing this additive phase and thus quantifying its impact on performance. Herein, an additive-phase generation algorithm has been developed to remedy this limitation and identify percolation threshold used to define a minimal additive loading. Improved ionic transport coefficients from reducing additive loading has been then quantified through homogenization calculation, macroscale model fitting, and experimental symmetric cell measurement, with good agreement between the methods. Rate capability test demonstrates capacity improvement at fast charge at the beginning of life, from 37% to 55%, respectively for high and low additive loading during 6C CC charging, in agreement with macroscale model, and attributed to a combination of lower cathode impedance, reduced electrode tortuosity and cathode thickness.

25 ENERGY STORAGE↗
DOE OSTI2019

Impact of Time-Varying Passenger Loading on Conventional and Electrified Transit Bus Energy Consumption

Transit bus passenger loading changes greatly over the course of a workday. Therefore, time-varying vehicle mass as a result of passenger load becomes an important factor in instantaneous energy consumption. Battery-powered electric transit buses have restricted range and longer 'fueling' time compared with conventional diesel-powered buses; thus, it is vital to know how much energy they require. Our previous work has shown that instantaneous transit bus mass can be obtained by measuring the pressure in the vehicle's airbag suspension system. This report leverages this novel technique to determine the impact of time-varying mass on energy consumption. Sixty-five days of velocity and mass data were collected from in-use transit buses operating on routes in the Twin Cities, MN metropolitan area. The simulation tool Future Automotive Systems Technology Simulator was modified to allow both velocity and mass as time-dependent inputs. This tool was then used to model an electrified and conventional bus on the same routes and determine the energy use of each bus. Results showed that the kinetic intensity varied from 0.27 to 4.69 mi-1 and passenger loading ranged from 2 to 21 passengers. Simulation results showed that energy consumption for both buses increased with increasing vehicle mass. The simulation also indicated that passenger loading has a greater impact on energy consumption for conventional buses than for electric buses owing to the electric bus's ability to recapture energy. This work shows that measuring and analyzing real-time passenger loading is advantageous for determining the energy used by electric and conventional diesel buses.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2015

Intermediate-scale Fire Performance of Composite Panels under Varying Loads

New aircraft are being designed with increasing quantities of composite materials used in their construction. Different from the more traditional metals, composites have a higher propensity to burn. This presents a challenge to transportation safety analyses, as the aircraft structure now represents an additional fuel source involved in the fire scenario. Most of the historical fire testing of composite materials is aimed at studying kinetics, flammability or yield strength under fire conditions. Most of this testing is small-scale. Heterogeneous reactions are often length-scale dependent, and this is thought to be particularly true for composites which exhibit significant microscopic dynamics that can affect macro-scale behavior. We have designed a series of tests to evaluate composite materials under various structural loading conditions with a consistent thermal condition. We have measured mass-loss, heat flux, and temperature throughout the experiments. Several types of panels have been tested, including simple composite panels, and sandwich panels. The main objective of the testing was to understand the importance of the structural loading on a composite to its behavior in response to fire-like conditions. During flaming combustion at early times, there are some features of the panel decomposition that are unique to the type of loading imposed on the panels. At load levels tested, fiber reaction rates at later times appear to be independent of the initial structural loading.

36 MATERIALS SCIENCE↗