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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Chapter 9: Impact of Variable Renewable Energy Sources on Bulk Power System Planning and Operations

Wind and solar photovoltaics (PV) have experienced remarkable growth in recent years, with many consequent benefits within and outside of power systems. At the same time, wind and solar PV have unique characteristics relative to the historically dominant dispatchable technologies like coal, gas, and nuclear power plants that have required and will continue to require changes in power system planning and operations. This chapter discusses planning and operational challenges of integrating wind and solar PV into bulk power systems. We first present the key characteristics of wind and solar PV that differentiate it from conventional technologies, such as variable and uncertain electricity generation, asynchronous interconnection to the power system, and near-zero marginal costs. We then link these characteristics to power system planning and operational challenges at low through high wind and solar penetrations. Finally, we discuss near- and long-term solutions to those challenges, such as diversifying the generation mix and wind and solar fleets, improving system flexibility, diversifying ancillary service products, and integrating generation and transmission planning.

bulk power system↗
DOE OSTI2023

Electric Vehicle Managed Charging: Estimating the Potential Bulk Power System Value

With more and more electric vehicles (EVs) on the road, the grid of the future can greatly benefit from EV managed charging, which coordinates charging based on people's travel needs, electricity supply, and grid conditions. The added flexibility could be especially valuable for the bulk power system as it transitions to high shares of variable renewable generation, like wind and solar. Numerous studies have estimated the potential value of EV managed charging. In this study, NREL leveraged more detailed modeling of EV adoption, use, charging, and bulk power system operations to understand the potential value. Unique to this study, NREL modeled different charging flexibility types and dispatch mechanisms - as well as participation rates among drivers in having their EV charging managed - starting from vehicle-specific descriptions of charging flexibility. The study is based on a passenger light-duty vehicle adoption scenario with 100% EV sales by 2035 and a New England power system in 2038 with 84% clean generation and 26% of the electric load met by net imports. The 2038 New England light-duty vehicle feet is modeled as 45% electric.

ADVANCED PROPULSION SYSTEMS,ENERGY PLANNING, POLIC↗
DOE OSTI2016

Elucidating the interaction between Ni and CeO x in ethanol steam reforming catalysts: A perspective of recent studies over model and powder systems

Bulk metallic nickel is a poor catalyst for the reforming of oxygenates being deactivated by the deposition of coke. In contrast, Ni-ceria is an active system for the catalytic extraction of H2 from the ethanol steam reforming reaction (ESR, C 2 H 5 OH + 3H 2 O ↔ 2CO 2 + 6H 2 ). Numerous studies, with model (well-defined crystal surfaces) and technical (high surface area powders) catalysts, have been devoted to understand the fundamental role of each catalyst component, the performance of adjacent sites in the metal-oxide interface, and the complex mechanistic steps that convert two oxygenated reactants (ethanol and H 2 O) into H 2 . The size and low loading of Ni on ceria facilitate metal-oxide support interactions that probably enhance the reactivity of the system. To establish the precise role of both Ni and Ce is challenging. However it is clear that both Ni and Ce are associated with the dissociation of H 2 O (OH + H), while ceria readily adsorbs and partially dissociates ethanol (i.e. ethoxy formation). The most difficult step of Csingle bondC bond dissociation likely occurs only on Ni or at the Ni-Ce interface. H 2 O and OH remain as important agents for the prevention of excess C build up during the C—H/C—C dissociation process. Often, deactivation upon C build up, is a direct result of Ni sintering and decoupling of the Ni-Ce interactions. One strategy to maintain good activity and stability is to protect the Ni-Ce interaction, and this can be achieved through the use of solid solutions (Ce 1–x Ni x O 2–y ) or by employing stabilizing agents such as W (Ni x W y Ce z O 2 ). In this study, we present and discuss the most recent work for the ESR reaction and show the important role of ceria which participates directly in the reaction and also enhances catalytic activity through metal-support interactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

A review of the potential impacts of climate change on bulk power system planning and operations in the United States

In this paper, climate change might impact various components of the bulk electric power system, including electricity demand; transmission; and thermal, hydropower, wind, and solar generators. Most research in this area quantifies impacts on one or a few components and does not link these impacts to effects on power system planning and operations. Here, we advance the understanding of how climate change might impact the bulk U.S. power system in three ways. First, we synthesize recent research to capture likely component-level impacts of climate change in the United States. Second, given the interconnected nature of the electric power system, we assess how aggregated component-level impacts might affect power system planning and operations. Third, we outline an agenda for future research on climate change impacts on power system planning and operations. Although component-level impacts vary in their magnitude, collectively they might significantly affect planning and operations. Most notably, increased demand plus reduced firm capacity across generation types might require systems to procure significant additional capacity to maintain planning reserve margins, and regional declines in renewable resources might need to be offset by increasing zero-carbon investment to meet decarbonization targets. Aggregated impacts might also affect operations, e.g., through shifts in dispatching and increased operational reserve requirements. Future research should aggregate component-level impacts at operational timescales, quantify impacts on wind and solar variability, and contextualize climate change impacts within ongoing shifts in the electric power system.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2025

RE-INTEGRATE EMT Simulation Tool: Input Data Processing Layer for Bulk Power System

This paper introduces an advanced input data processing layer for EMT simulations of large-scale bulk power systems. The paper proposes two versions of the RE-INTEGRATE EMT simulation tool, RE-INTEGRATE Gen-0 and RE-INTEGRATE Gen-1, which are developed to enhance simulation generalizability, scalability, and accuracy. The framework leverages a generic class design for components to incorporate linear equations, which are generated by discretizing the Differential-Algebraic Equations (DAEs) that represent the dynamics of the components. In addition, the framework employs a parsing algorithm that parses a power system’s raw and dyr files to generate a connectivity graph which is then traversed to form the overall system’s dynamics. The proposed input data processing layer is used to simulate the IEEE 39-bus test system. The obtained results demonstrate the framework’s capability to achieve simulation scalability and accuracy. Further, the results indicate that EMT simulations performed using the proposed automations can effectively handle complex grid configurations.

Mishra, Rahul [ORNL] (ORCID:0000000328205932)↗
DOE OSTI2016

The effect of the NERC CIP standards on the reliability of the North American Bulk Electric System

Considerable money and effort has been expended by generation, transmission, and distribution entities in North America to implement the North American Electric Reliability Corporation (NERC) Critical Infrastructure Protection (CIP) standards for the bulk electric system. Assumptions have been made that as a result of the implementation of the standards, the grid is more cyber secure than it was pre-NERC CIP, but are there data supporting these claims, or only speculation? Has the implementation of the standards had an effect on the grid? Furthermore, developing a research study to address these and other questions provided surprising results.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2017

Impact of Distributed Energy Resources on the Bulk Electric System: Combined Modeling of Transmission and Distribution Systems and Benchmark Case Studies

The high penetration of distributed energy resources (DERs) on modern distribution systems introduces intermittent power generation, stochastic system operating conditions, and bi-directional power flows that impact the system responses to various types of disturbances and may pose challenges to the operations and reliability of the Bulk Electric System (BES). In order to understand the impact of DERs on the planning and operation of the BES, the distribution system can no longer be represented as a single load at a node on the transmission system. At the same time, advanced control capabilities of DERs offer potential opportunities for improving BES reliability by transforming DERs from a passive “do no harm” resource to an active “support reliability” resource when applied in a planned and well-thought-out manner. This concept is often described as DER “flexibility.” With the persistent trend towards a high- penetration of DERs in distribution systems, regulators such as the North American Electric Reliability Corporation (NERC), planning coordinators and grid operators are in serious need of understanding the full-spectrum impact of DERs on the BES to ensure secure and reliable grid planning and operations.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2022

Electric Vehicle Managed Charging: Forward-Looking Estimates of Bulk Power System Value

When and where electric vehicle charging occurs has significant implications for power systems supporting widespread electric vehicle deployment with high shares of wind and solar generation. Numerous studies have estimated the value of scheduling or otherwise managing electric vehicle charging in such power systems. This study improves on those earlier works by leveraging detailed simulation models for electric vehicle adoption, electric vehicle use, electric vehicle charging, and bulk power system operations; and linking them with methods for describing charging flexibility at both the individual vehicle and aggregate levels. This study closely analyzes electric vehicle managed charging (EVMC) performance along the dimensions of flexibility type (within-charging session or within-week scheduling), dispatch mechanism (direct load control or one of several price-based mechanisms), and participation rate, under the assumptions of ubiquitous chargers and all trips completed on time. The study is located in a passenger light-duty vehicle adoption scenario with 100% electric vehicle sales by 2035, and in an envisioned 2038 New England power system for which within-region generation is 84% clean.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2022

Electrification Futures Study: Impact of Electric Vehicles on Bulk Power Systems

This presentation builds on work presented at IEW2019 on "Transportation Scenarios of Electric Technology Adoption and Power Consumption" by providing insights on the impact of demand-side electrification, and electric vehicles in particular, on electricity supply and bulk power systems. This talk summarizes some results from the multi-year and multi-stakeholder Electrification Futures Study (EFS) series of reports. In particular, this work leverages integrated demand and supply modelling of future energy systems to provide insights on system design and operations focusing on demand flexibility and integration of variable renewables.

ADVANCED PROPULSION SYSTEMS,ENERGY PLANNING, POLIC↗
DOE OSTI2024

Grid-Forming Inverters for Stability Improvements in Bulk Power Systems with High Inverter-Based Resources Penetration

The grid-forming inverter (GFM) has been considered recently as a means to enhance grid stability in areas with Inverter-based Resources (IBRs) concentration. This paper assesses the potential improvements the GFM can bring to Bulk-power Systems (BPS) through two distinct studies. The first study was conducted on West Texas in ERCOT with presence of more than 35GW of IBRs, the Grid-Following (GFL) batteries were replaced with GFM batteries. The results demonstrate that the GFM significantly improved the voltage profile and active power injection during and after a fault. The second study focused on a local area within ERCOT grid. In this case, a battery operating as GFL within the local study area was replaced with a GFM battery. The findings clearly illustrate that GFM can strengthen the area and allow a higher IBRs power generation and a higher power export from the local study area.

Quedan, Amro↗
DOE OSTI2019

Bulk Power System Dynamics with Varying Levels of Synchronous Generators and Grid-Forming Power Inverters: Preprint

Inverters using phase-locked loops for control depend on voltages generated by synchronous machines to operate. This might be problematic if much of the conventional generation fleet is displaced by inverters. To solve this problem, grid-forming control for inverters has been proposed as being capable of autonomously regulating grid voltages and frequency. Presently, the performance of bulk power systems with massive penetrations of grid-forming inverters has not been thoroughly studied to elucidate benefits. Hence, this paper presents inverter models with two grid-forming strategies: virtual oscillator control and droop control. The two models are specifically developed to be used in positive-sequence simulation packages and have been implemented in PSLF. The implementations are used to study the performance of bulk power grids incorporating inverters with grid-forming capability. Specifically, simulations are conducted on a modified IEEE 39-bus test system and the micro-WECC test system with varying levels of synchronous and inverter-based generation. The dynamic performance of the tested systems with grid-forming inverters during contingency events is better than cases with only synchronous generation.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2020

Power HIL Evaluation of Inverter Controls for 100% Inverter-Based Bulk Power Systems

NREL's Power Electronic Grid Interface (PEGI) Workshop, held October 13, 2020, focused on the research challenges of operating power systems with ever-higher levels of inverter-based generation and power-electronic-based load. This presentation discusses a power hardware-in-the-loop evaluation of inverter controls for 100% inverter-based bulk power systems.

grid integration↗
DOE OSTI2025

A VSC-HVDC-Assisted Black-Start Strategy in Bulk Power Systems a Case Study in San Diego

With the worldwide growth in deploying high-voltage direct current (HVDC) transmission systems, their ability to facilitate black-start (BS) restoration has been a research topic of interest. In this context, voltage source converter (VSC)-HVDC is regarded as a BS resource, and this paper proposes a VSC-HVDC-assisted parallel BS restoration strategy in bulk power systems. The proposed strategy consists of two stages: 1) determination of the VSC and generator startup sequence and 2) load restoration simulation. In the first stage, the entire blackout system is sectionalized into multiple subsystems. Each subsystem includes a VSC-HVDC station or traditional BS unit, it independently determines its generator startup timeline and the energization timelines for buses and lines. The second stage involves load restoration, conceptualized as a modified unit commitment problem, with the timelines established in the first stage work as critical inputs. The proposed BS restoration strategy is tested on the San Diego power system to simulate the 2011 Southwest blackout. The simulation results validate the effectiveness of using VSC-HVDC links as a BS resource which not only speeds up the restoration process but also reduces both energy and economic losses.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2020

Preserving Symmetry and Degeneracy in the Localized Orbital Scaling Correction Approach

Symmetry is a fundamental concept that plays a critical role in many chemical and physical phenomena and processes, which highlights the importance of theoretical methods to correctly handle symmetry. The recently developed localized orbital scaling correction (LOSC1) shows great improvement on the description of band gaps, photoemission spectra, and dissociation limits of cationic species. However, issues remain with LOSC1 in dealing with the symmetry and degeneracy of electronic states, which are also relevant to other methods using localization. In this work, we utilize a new method that deals with the physical-space and the energy-space localization on an equal footing. The resulting localized orbitals, i.e., orbitalets, are able to maintain more symmetry and the desired state degeneracy, which is important in calculating the electronic structure of both molecules and periodic bulk systems. Furthermore, the curvature matrix is redefined to improve potential energy curves for systems with stretched bonds, while retaining the correct dissociation limits. This new approach, termed LOSC2, includes only two fitting parameters. It maintains accuracy similar to that of LOSC1 over many properties, while overcoming LOSC1’s deficiencies in symmetry and degeneracy. Our tests have shown that LOSC2 orbitalets possess the full- or subgroup of molecular symmetry if allowed, which preserves the state degeneracy. Tests on differently sized planar annulenes, odd-numbered allenes, and triphenylene again verify that LOSC2 is able to maintain the state degeneracy, while LOSC1 cannot. Finally, all the tests demonstrate the advantage of LOSC2 in the calculation of molecular systems and its potential for application to periodic bulk systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Opportunities for wave energy in bulk power system operations

Wave energy resources have high, yet largely untapped potential as candidate generation technology. In this paper, we perform a data-driven analysis to characterize the impact of wave energy integration on bulk-scale power systems and market operations. Through data-driven sensitivity studies centered on an optimization-based production cost modeling formulation, our work characterizes the inflection point beyond which wave integration starts impacting power system operations, considering present day transmission infrastructure. Furthermore, our analysis also considers the joint effects of wave energy integration and system-wide transmission expansion. Finally, potential resilience scenarios such as wildfire-driven transmission contingencies and heat wave events are investigated, whereby the contributions of grid-integrated wave energy in alleviating the effects of the resilience events are analyzed. As our demonstration test bed, we consider a reduced-order network topology for the U.S. Western Interconnection with wave energy generation integrated at carefully selected sites across the coastal areas of Washington, Oregon, and northern California. Our results indicate that over a representative year of operations, wave energy integration systematically reduces locational marginal prices (LMPs) of energy and price volatility, especially during periods of high wave resource availability (winter months for the U.S. west coast). Average, maximum, and minimum of hourly LMPs over a typical year of operation was reduced by 2.95, 51.28, and 1.13 $\$$/MWh respectively (over a baseline scenario with no wave energy integration), when the selected network model had a total of 5000 MW wave power installed capacity during the representative year of study. The effects of wave energy integration can remain localized with existing transmission infrastructure (identified to be most pronounced in the Pacific Northwest region in the example we studied). However, with concurrent transmission expansion, the impacts of wave energy integration are likely to have a higher geographical spread. Our results also indicate that wave energy may be able to assist power system operations during resilience events such as major transmission contingencies and heat wave events, although such benefits might be dependent on factors such as proximity of affected area to wave resources, availability of adequate resource potential and adequate transmission capacity.

16 TIDAL AND WAVE POWER↗
DOE OSTI2020

High electrification futures: Impacts to the U.S. bulk power system

Electrification of end-use technologies could have important implications for bulk power sector planning, operations, and impacts. By combining previously-defined electrification scenarios with capacity expansion modeling, we evaluate the potential challenges and opportunities associated with electrification. Our scenario analysis reveals that electrification reduces energy consumption and air emissions from across the energy sector, and its impacts on energy system costs are modest due, in part, to the abundance of low-cost resources in the United States.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2019

Interactions between displacement cascade and dislocation and their influences on Peierls stress in Fe-20Cr-25Ni alloys

The interactions between dislocations and displacement cascades are investigated using molecular dynamics simulations. The primary knock-on atoms (PKAs) are placed at different distances to edge and screw dislocation lines. Specifically, an fcc Fe-20Cr-25Ni system is studied; the alloy is the based alloy for Alloy 709. The number of defects is calculated using Wigner-Seitz analysis in order to illustrate the effect of dislocations on cascades. The displacement cascades in systems containing dislocations tend to generate more total defects compared with bulk systems, but eventually lead to less surviving defects in the materials matrix due to interactions with dislocations. The changes in atomic structures of the dislocations after interacting with cascades are analyzed to understand how the primary damage affects dislocations. The displacement cascade potentially causes dislocation climb in edge dislocations and cross-slip in screw dislocations, which could serve as additional mechanisms contributing to the radiation-induced hardening (RIH) compared with conventional RIH models. To reveal this, Peierls stresses are calculated before and after cascades using molecular static simulations. This study provides critical information of how defect production and dislocations are correlated, especially when total dose is high, which needs to be taken into account in upper scale models, such as mean-field rate theory.

Lu, Zizhe↗