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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Foundations for the Future Power System: Inverter-Based Resource Interconnection Standards

As power systems evolve to become reliant on solar, wind, batteries, and other inverter-based resources (IBRs), it is essential that those resources meet certain minimum performance and capability criteria designed to ensure the power system operates stably and reliably. Because those criteria, as enshrined in interconnection standards, take years to develop and are very long lived, they need to account for not only the present state of the power system but also its expected future state over the lifetime of the power plants to which they will apply. In addition, they need to be specific enough to ensure reliability without over specifying and, thereby, impeding innovation. Because power systems are shifting rapidly from a state where IBRs make up a small to medium portion of generation to one where the generation will, at times, come predominantly from IBRs, interconnection standards are especially challenging to develop today. Good interconnection standards can make the power system more reliable and less costly to operate, whereas poorly designed standards can lead to major problems, like the famous German 50.2-Hz problem, which introduced a risk of losing many gigawatts of solar on a frequency excursion and resulted in many IBRs being retrofitted at great cost to mitigate a major system reliability risk. Readying the power system by specifying forward-looking technical minimum functional capabilities for IBRs can be an effective approach to avoid future retrofits.

data models↗
NASA NTRS2011

Grid-Tied Photovoltaic Power System

A grid-tied photovoltaic (PV) power system is connected directly to the utility distribution grid. Facility power can be obtained from the utility system as normal. The PV system is synchronized with the utility system to provide power for the facility, and excess power is provided to the utility. Operating costs of a PV power system are low compared to conventional power technologies. This method can displace the highest-cost electricity during times of peak demand in most climatic regions, and thus reduce grid loading. Net metering is often used, in which independent power producers such as PV power systems are connected to the utility grid via the customers main service panels and meters. When the PV power system is generating more power than required at that location, the excess power is provided to the utility grid. The customer pays the net of the power purchased when the on-site power demand is greater than the onsite power production, and the excess power is returned to the utility grid. Power generated by the PV system reduces utility demand, and the surplus power aids the community. Modern PV panels are readily available, reliable, efficient, and economical, with a life expectancy of at least 25 years. Modern electronics have been the enabling technology behind grid-tied power systems, making them safe, reliable, efficient, and economical with a life expectancy equal to the modern PV panels. The grid-tied PV power system was successfully designed and developed, and this served to validate the basic principles developed, and the theoretical work that was performed. Grid-tied PV power systems are reliable, maintenance- free, long-life power systems, and are of significant value to NASA and the community. Of particular value are the analytical tools and capabilities that have been successfully developed. Performance predictions can be made confidently for grid-tied PV systems of various scales. The work was done under the NASA Hybrid Power Management (HPM) Program, which is the integration of diverse power devices in an optimal configuration for space and terrestrial applications.

Eichenberg, Dennis J.↗
DOE OSTI2015

Optimal subinterval selection approach for power system transient stability simulation

Power system transient stability analysis requires an appropriate integration time step to avoid numerical instability as well as to reduce computational demands. For fast system dynamics, which vary more rapidly than what the time step covers, a fraction of the time step, called a subinterval, is used. However, the optimal value of this subinterval is not easily determined because the analysis of the system dynamics might be required. This selection is usually made from engineering experiences, and perhaps trial and error. This paper proposes an optimal subinterval selection approach for power system transient stability analysis, which is based on modal analysis using a single machine infinite bus (SMIB) system. Fast system dynamics are identified with the modal analysis and the SMIB system is used focusing on fast local modes. An appropriate subinterval time step from the proposed approach can reduce computational burden and achieve accurate simulation responses as well. As a result, the performance of the proposed method is demonstrated with the GSO 37-bus system.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS2016

Science Instrument Sensitivities to Radioisotope Power System Environment

Radioisotope Power Systems (RPS) have been and will be enabling or significantly enhancing for many missions, including several concepts identified in the 2011 Planetary Science Decadal Survey. Some mission planners and science investigators might have concerns about possible impacts from RPS-induced conditions upon the scientific capabilities of their mission concepts. To alleviate these concerns, this paper looks at existing and potential future RPS designs, and examines their potential radiation, thermal, vibration, electromagnetic interference (EMI), and magnetic fields impacts on representative science instruments and science measurements. Radiation impacts from RPS on science instruments are of potential concern for instruments with optical detectors and instruments with high-voltage electronics. The two main areas of concern are noise effects on the instrument measurements, and long-term effects of instrument damage. While RPS by their nature will contribute to total radiation dose, their addition for most missions should be relatively small. For example, the gamma dose rate from one Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) would be an order of magnitude lower than the environmental dose rate at Mars, and would have a correspondingly lower contribution to instrument noise and to any permanent damage to payload sensors. Increasing the number of General Purpose Heat Source (GPHS) modules used in an RPS would be expected to increase the generated radiation proportionally; however, the effect of more GPHS modules is mitigated from a strictly linear relationship by self-shielding effects. The radiation field of an RPS is anisotropic due to the deviation of the modules from a point-source-geometry. For particularly sensitive instruments the total radiation dose could be mitigated with separation or application of spot shielding. Though a new, higher-power RPS could generate more heat per unit than current designs, thermal impact to the flight system could be mitigated with shading and pointing if required by the mission. Alternatively, excess heat could prove beneficial in providing needed heat to spacecraft components and instruments in some thermal environments. Vibration for a new higher-power Stirling Radioisotope Generator (SRG) would be expected to be similar to the recent Advanced Stirling Radioisotope Generator (ASRG) design. While vibration should be low, it must be considered and addressed during spacecraft and instrument design. EMI and magnetic fields for new RPS concepts are expected to be low as for the current RPS, but must be considered and addressed if the mission includes sensitive instruments such as magnetometers. The assessment conducted for this paper focused on orbiter instrument payloads for two representative mission concepts- a Titan Saturn System Mission (TSSM) and a Uranus Orbiter and Probe (UOP)-since both of these Decadal Survey concepts would include many diverse instruments on board. Quick-look design studies using notional new RPS concepts were carried out for these two mission concepts, and their specific instrument packages were analyzed for their interactions with new RPS designs. The original Decadal Survey TSSM and UOP concepts did not have complete instrument performance requirements so typical measurement requirements were used where needed. Then, the general RPS environments were evaluated for impacts to various types of instruments. This paper describes how the potential impacts of the RPS on science instruments and measurements were assessed, which impacts were addressed, proposed mitigation strategies against those impacts, and provides an overview of future work.

RPS↗
DOE OSTI2014

Co-Simulation of Detailed Whole Building with the Power System to Study Smart Grid Applications

Modernization of the power system in a way that ensures a sustainable energy system is arguably one of the most pressing concerns of our time. Buildings are important components in the power system. First, they are the main consumers of electricity and secondly, they do not have constant energy demand. Conventionally, electricity has been difficult to store and should be consumed as it is generated. Therefore, maintaining the demand and supply is critical in the power system. However, to reduce the complexity of power models, buildings (i.e., end-use loads) are traditionally modeled and represented as aggregated “dumb” nodes in the power system. This means we lack effective detailed whole building energy models that can support requirements and emerging technologies of the smart power grid. To gain greater insight into the relationship between building energy demand and power system performance, it is important to constitute a co-simulation framework to support detailed building energy modeling and simulation within the power system to study capabilities promised by the modern power grid. This paper discusses ongoing work at Pacific Northwest National Laboratory and presents underlying tools and framework needed to enable co-simulation of building, building energy systems and their control in the power system to study applications such as demand response, grid-based HVAC control, and deployment of buildings for ancillary services. The optimal goal is to develop an integrated modeling and simulation platform that is flexible, reusable, and scalable. Results of this work will contribute to future building and power system studies, especially those related to the integrated ‘smart grid’. Results are also expected to advance power resiliency and local (micro) scale grid studies where several building and renewable energy systems transact energy directly. This paper also reviews some applications that can be supported and studied using the framework introduced to understand their implications before they can be successfully implemented in the power system.

Makhmalbaf, Atefe↗
DOE OSTI2018

The Role of Concentrating Solar Power Toward High Renewable Energy Penetrated Power Systems

Achieving high renewable energy penetrated power systems requires considerable operational flexibility to hedge the variability and uncertainty of variable renewable energy (VRE) generation. Compared with VRE sources, concentrating solar power (CSP) is an emerging controllable renewable generation technique that utilizes solar thermal power to generate electricity. The operational dispatchability of CSP would contribute to the power system transition toward high renewable penetration. In this paper, we explore how the generation portfolio will change toward high renewable energy penetrations, how much cost is involved, and what role CSP will play in realizing a high renewable energy penetrated power system. This study relies on a stochastic two-stage generation and transmission expansion planning model with CSP plants. The model captures the uncertainty and variability of renewable generation and the flexibility limits of thermal plants. With the target of achieving a renewable-dominated minimum-cost system with an expected renewable energy penetration level, the investments of both generation and transmission facilities are optimized. A case study on IEEE test systems with renewable technology cost data in 2050 is performed to analyze the value of CSP toward high renewable energy penetrated power systems.

14 SOLAR ENERGY↗
DOE OSTI2022

Power System Resilience Evaluation Framework and Metric Review

Power system resilience has been an emerging hot topic in recent years to investigate the increasing threats of extreme events, such as natural disasters, severe weather, and cyberattacks. Although much research has been done to define, model, and quantify resilience from different aspects, the lack of universally accepted evaluation methods and resilience metrics makes it difficult to assess and compare resilience across different power systems, such as what is typically done in power system reliability studies. In this paper, first, we review the definitions of resilience, and we summarize two core concepts shared by most of the literature. Then, we develop a new framework to assess power system resilience from two perspectives - i.e., pre-event estimation and post-event evaluation - to capture system resilience performance in both general and specific fashions. We conduct a thorough review of existing resilience metrics and categorize them using the proposed framework, where recommendations are also proposed to capture core concepts of resilience.

power system resilience↗
NASA NTRS1990

The environment power system analysis tool development program

The Environment Power System Analysis Tool (EPSAT) is being developed to provide space power system design engineers with an analysis tool for determining system performance of power systems in both naturally occurring and self-induced environments. The program is producing an easy to use computer aided engineering (CAE) tool general enough to provide a vehicle for technology transfer from space scientists and engineers to power system design engineers. The results of the project after two years of a three year development program are given. The EPSAT approach separates the CAE tool into three distinct functional units: a modern user interface to present information, a data dictionary interpreter to coordinate analysis; and a data base for storing system designs and results of analysis.

Jongeward, Gary A.↗
NASA NTRS1994

Power Systems for Future Missions: Appendices A-L

Selection of power system technology for space applications is typically based on mass, readiness of a particular technology to meet specific mission requirements, and life cycle costs (LCC). The LCC is typically used as a discriminator between competing technologies for a single mission application. All other future applications for a given technology are usually ignored. As a result, development cost of a technology becomes a dominant factor in the LCC comparison. Therefore, it is common for technologies such as DIPS and LMR-CBC to be potentially applicable to a wide range of missions and still lose out in the initial LCC comparison due to high development costs. This collection of appendices (A through L) contains the following power systems technology plans: CBC DIPS Technology Roadmap; PEM PFC Technology Roadmap; NAS Battery Technology Roadmap; PV/RFC Power System Technology Roadmap; PV/NAS Battery Technology Roadmap; Thermionic Reactor Power System Technology Roadmap; SP-100 Power System Technology Roadmap; Dynamic SP-100 Power System Technology Roadmap; Near-Term Solar Dynamic Power System Technology Roadmap; Advanced Solar Dynamic Power System Technology Roadmap; Advanced Stirling Cycle Dynamic Isotope Power System Technology Roadmap; and the ESPPRS (Evolutionary Space Power and Propulsion Requirements System) User's Guide.

Gill, S. P.↗
DOE OSTI2013

Cost Study for Manufacturing of Solid Oxide Fuel Cell Power Systems

Solid oxide fuel cell (SOFC) power systems can be designed to produce electricity from fossil fuels at extremely high net efficiencies, approaching 70%. However, in order to penetrate commercial markets to an extent that significantly impacts world fuel consumption, their cost will need to be competitive with alternative generating systems, such as gas turbines. This report discusses a cost model developed at PNNL to estimate the manufacturing cost of SOFC power systems sized for ground-based distributed generation. The power system design was developed at PNNL in a study on the feasibility of using SOFC power systems on more electric aircraft to replace the main engine-mounted electrical generators [Whyatt and Chick, 2012]. We chose to study that design because the projected efficiency was high (70%) and the generating capacity was suitable for ground-based distributed generation (270 kW).

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2020

Electrical circuit control in power systems

Electrical circuit control techniques in power systems are disclosed herein. In one embodiment, a supervisory computer in the power system can be configured to fit phasor measurement data from phasor measurement units into a Gaussian distribution with a corresponding Gaussian confidence level. When the Gaussian confidence level of the fitted Gaussian distribution is above a Gaussian confidence threshold, the supervisory computer can be configured to perform an ambient analysis on the received phasor measurement data to determine an operating characteristic of the power system. The supervisory computer can then automatically applying at least one electrical circuit control action to the power system in response to the determined operating characteristic.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2023

Systems and methods for enhanced sequential power system model parameter estimation

A system for enhanced sequential power system model calibration is provided. The system is programmed to store a model of a device. The model includes a plurality of parameters. The system is also programmed to receive a plurality of events associated with the device, receive a first set of calibration values for the plurality of parameters, generate a plurality of sets of calibration values for the plurality of parameters, for each of the plurality of sets of calibration values, analyze a first event of the plurality of events using a corresponding set of calibration values to generate a plurality of updated sets of calibration values, analyze the plurality of updated sets of calibration values to determine a current updated set of calibration values, and update the model to include the current updated set of calibration values.

Wang, Honggang↗
NASA NTRS1967

Lunar power systems.

Lunar electric power systems transported by Saturn V noting Brayton cycle, Rankine cycle, solar cells and thermoelectric systems

ELECTRIC ENERGY↗
NASA NTRS1966

Photovoltaic power systems.

Solar photovoltaic power systems weight reduction and reliability noting applicability to propulsion, attitude control and stationkeeping missions

Goldsmith, J.↗