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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

Maturation of Dynamic Power Convertors for Radioisotope Power Systems

Dynamic Radioisotope Power Systems (DRPS) are being developed by NASA’s Radioisotope Power Systems (RPS) Program in collaboration with the U.S. Department of Energy (DOE) for space science and exploration missions. A development effort is currently underway to mature dynamic power convertors for infusion into a potential future flight generator. This convertor maturation effort was formulated by the RPS Program at NASA Headquarters based on successful maturation models and utilizes expertise from agency’s technology and mission centers to support requirements development and technology assessments. The effort is being executed by Glenn Research Center’s (GRC) DRPS Project and the Thermal Energy Conversion Branch. The Dynamic Power Convertor (DPC) contracts consist of three phases to enable design, fabrication, and independent assessment of prototypes after delivery to the government. The contracts are intended to gather data on candidate dynamic conversion technologies to fill knowledge gaps, support assessments of dynamic conversion technologies, and elicit generator requirements. The 110-watt Stirling Radioisotope Generator (SRG-110) and Advanced Stirling Radioisotope Generator (ASRG) flight development projects provided Stirling convertor demonstration units and engineering models to verify and validate convertors against performance specifications and mission requirements. These units utilize temperature resistant materials and non-contacting bearings to demonstrate wear-free, long-life operation. This maturation effort builds on past lessons-learned and new requirements focused on demonstrating convertor robustness to critical environments meant to stress key aspects of each convertor within the margins of the design. This effort seeks to realize the full potential of dynamic power conversion technologies for NASA’s space science and exploration missions.

Wilson, Scott↗
NASA NTRS1975

The ATS-6 power system - An optimized design for maximum power source utilization

The modified power system design adopted for the ATS-6 satellite is described. This design featured a shunt-boost configuration to provide direct power from the solar array to the loads for maximum efficiency. In addition, shunt power dissipators were used, not only as a means of power system regulation, but also for thermal control. A brief description of the spacecraft and of the initial series regulator power system design (which was unable to meet mission requirements) precede the discussion. The shunt boost system provides excellent utilization of array power with an 8 to 10% increase in efficiency over the original configuration; good array-battery static and dynamic load sharing; excellent flexibility in accommodating mission requirements; and low electromagnetic interference.

Lavigna, T. A.↗
DOE OSTI2017

Performance of Energy Storage with Nuclear and Renewable Power Systems

Nuclear power represents a traditional baseload power component to the grid, while renewables output variable amounts of power at unpredictable times. Nuclear and renewable energy integration (NREI) systems have previously been explored as valuable additions to the existing power grid. Energy storage systems can allow power plants to store energy mechanically using pumped hydro or compressed air, thermally using liquid salt or steam accumulators, or chemically with batteries. The addition of energy storage to NREI systems can allow for the discharge of electricity to adjust to demands placed on the grid. The allocation of energy to adjust to grid demand is explored through a historical 8,760-hour analysis including nuclear, wind, and solar NREI systems with energy storage. The operation of storage systems is compared through simulations of different storage and discharge parameters based off the maximum daily grid demands, and hourly electricity prices. The overall profitability of storage systems is determined by comparing simulation results for the overall net revenue increases exceeding storage efficiency losses. Several NREI systems have increased the value of electricity for both solar PV and wind energy, in combination with nuclear power. Optimization of these systems is developed using MATLAB code and the simulations of the most profitable results are explored.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
NASA NTRS2000

Analysis and Test of a Proton Exchange Membrane Fuel Cell Power System for Space Power Applications

An effort is underway to develop a prototype Proton Exchange Membrane (PEM) Fuel Cell breadboard system for fuhlre space applications. This prototype will be used to develop a comprehensive design basis for a space-rated PEM fuel cell powerplant. The prototype system includes reactant pressure regulators, ejector-based reactant pumps, a 4-kW fuel cell stack and cooling system, and a passive, membranebased oxygen / water separator. A computer model is being developed concurrently to analytically predict fluid flow in the oxidant reactant system. Fuel cells have historically played an important role in human-rated spacecraft. The Gemini and Apollo spacecraft used fuel cells for vehicle electrical power. The Space Shuttle currently uses three Alkaline Fuel Cell Powerplants (AFCP) to generate all of the vehicle's 15-20kW electrical power. Engineers at the Johnson Space Center have leveraged off the development effort ongoing in the commercial arena to develop PEM fuel cel ls for terrestrial uses. The prototype design originated from efforts to develop a PEM fuel cell replacement for the current Space Shuttle AFCP' s. In order to improve on the life and an already excellent hi storical record of reliability and safety, three subsystems were focused on. These were the fuel cell stack itself, the reactant circulation devices, and reactant / product water separator. PEM fuel cell stack performance is already demonstrating the potential for greater than four times the useful life of the current Shuttle's AFCP. Reactant pumping for product water removal has historically been accomplished with mechanical pumps. Ejectors offer an effective means of reactant pumping as well as the potential for weight reduction, control simplification, and long life. Centrifugal water separation is used on the current AFCP. A passive, membrane-based water separator offers compatibility with the micro-gravity environment of space, and the potential for control simplification, elimination of moving parts in an oxygen environment, and long life. The prototype system has been assembled from components that have previously been tested and evaluated at the component level. Preliminary data obtained from tests performed with the prototype system, as well as other published data, has been used to validate the analytical component models. These components have been incorporated into an integrated oxidant fluid system model. Results obtained from both the performance tests and the analytical model are presented.

Vasquez, Arturo↗
DOE OSTI2019

A Study of the Impact of Reduced Inertia in Power Systems

Inertia in power systems plays an important role in maintaining the stability and reliability of the system by counteracting changes in frequency. However, the traditional sources of synchronous generation are being displaced by renewable resources, which often have no inherent inertia. This paper investigates the impact of reduced system inertia on several aspects of the dynamic stability of power systems, such as angular stability, primary frequency response, and oscillatory modes. This study is performed on a large-scale 2000 bus synthetic Texas model by selectively replacing synchronous generators with inverter-based generation resources. This paper also compares the analysis results obtained by the above-mentioned inertia-reduction approach of renewable integration with another approach in which the inertia constant of all synchronous generators is decreased. This paper demonstrates that only reducing the inertia of all synchronous generators in a system does not provide an accurate analysis of the challenges associated with the reduced system inertia caused by renewable integration.

System Inertia, Angular stability, System Inertial↗
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↗
NASA NTRS1987

Study of the generator/motor operation of induction machines in a high frequency link space power system

Static power conversion systems have traditionally utilized dc current or voltage source links for converting power from one ac or dc form to another since it readily achieves the temporary energy storage required to decouple the input from the output. Such links, however, result in bulky dc capacitors and/or inductors and lead to relatively high losses in the converters due to stresses on the semiconductor switches. The feasibility of utilizing a high frequency sinusoidal voltage link to accomplish the energy storage and decoupling function is examined. In particular, a type of resonant six pulse bridge interface converter is proposed which utilizes zero voltage switching principles to minimize switching losses and uses an easy to implement technique for pulse density modulation to control the amplitude, frequency, and the waveshape of the synthesized low frequency voltage or current. Adaptation of the proposed topology for power conversion to single-phase ac and dc voltage or current outputs is shown to be straight forward. The feasibility of the proposed power circuit and control technique for both active and passive loads are verified by means of simulation and experiment.

Lipo, Thomas A.↗
DOE OSTI2019

Assessment of the Time a Power System Remains in the Power Deficit Zone as a Function of the Scale Factor for Wind-Power Plants

The scale factor for the use of power plants of a certain type refers to the fraction of their use in the overall energy balance of the system. Energy production by wind power plants depends directly on the wind conditions in a particular location and is stochastic in character. Increasing the fraction of these installations in the overall balance of a system also requires an increase in the power reserve capacity. Here the time a power system remains in the power deficit zone is estimated as a function of the fraction of wind power plants in the system structure. Two approaches to the placement of wind power units within a power system are compared– individual components and a system of a set of components. It is concluded that even within a small power system, combining geographically distributed components with favorable and unfavorable wind conditions into a system can have a positive effect on all the components within certain ranges of the scale factor.

17 WIND ENERGY↗
NASA NTRS1979

Automated management of power systems

APSM (Automated Power System Management) is a technology readiness program underway to develop, evaluate, and demonstrate various techniques involved in power system monitoring, as well as computational and control functions. The demonstration breadboard consists of the Viking Orbiter '75 power subassembly breadboard modified to incorporate dedicated microprocessors and digital interface circuits, as well as test support equipment for both spacecraft and ground computer simulation, fault simulation, and data acquisition.

Imamura, M. S.↗
NASA NTRS1981

Flight performance of the Voyager electrical power system

The Voyager power subsystem is described, and its flight performance to date is discussed. Special attention is given to the performance of the primary power source radioisotope thermoelectric generators (RTGs), to the autonomous operation features of the power system, and to the load management strategy developed to maintain an adequate power margin during application of transient loads and as normal degradation reduces RTG capability. It is found that the flight performance of the power system has been without significant problems to date and that RTG performance has exceeded mission requirements.

Packard, L. A.↗
DOE OSTI2022

A Solar-assisted Voltage Optimization Method for Transmission Solar Network Power System

This paper proposes a new formulation and solution algorithm that uses transmission level solar inverters to address the security-constrained optimal power flow (SCOPF) problem. The goal is to stabilize voltage fluctuations in transmission networks in base case and contingency scenarios, by using bulk solar power plant with a minimal number of post-contingency corrections. To achieve this goal, a two-stage volt/var optimization method is proposed to first correct all voltage violations with the volt-var alternating current optimal power flow (ACOPF) algorithm for a base case. Then a linearized SCOPF volt-var control algorithm is proposed to identify the corrective actions for all potential voltage violations in all contingency scenarios. The proposed method was tested and validated on a modified IEEE 118-bus system with solar photovoltaic (PV) data.

Photovoltaic, Volt/Var Control↗
DOE OSTI2022

ReNew100: Reliable Power System Operation with 100% Renewable Generation

The ReNew100 project has developed and demonstrated an operator support system (OSS) to operate power systems with 100% renewable power generation from inverter-based resources (IBRs) like wind and solar that significantly reduces the risk of widespread power outages in a simulated operational environment at Technology Readiness Level (TRL) 6. The OSS achieves resilient operation for power systems under changing operation modes including varying combinations of conventional and renewable generation, including cases with 100% renewable generation from wind and solar IBRs. The OSS continuously monitors the N-1 security of the power system, which refers to the ability of the power systems to survive single outages of power system elements, like the loss of a generator or a power line, without causing widespread power outages beyond those expected and planned for. If the OSS identifies that the system is not N-1 secure, an automatic Controller Parameter Optimization (CoPO) developed within Renew100 is activated to optimize the N-1 security of the system by tuning controller parameters within different assets like batteries, wind, and solar plants. The core innovation of ReNew100 is the development of this CoPO as well as the demonstration of the OSS for a real-time simulation of the Hawai'i Island power system. Moreover, Renew100 has developed new model calibration techniques for dynamic power system models and demonstrated them for Hawai'i Island.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2021

Dynamic consensus and extended high gain observers as a tool to achieve practical frequency synchronization in power systems under unknown time-varying power demand

In this paper, we consider the frequency synchronization problem in a network of lossless, connected, and network-reduced power system. Frequency synchronization is an important problem in power systems as frequency deviation can lead to degraded power quality, tripping of generators, etc. We present a load-estimator-based consensus algorithm in a network of fourth-order generator models that achieves practical frequency synchronization in the presence of unknown time-varying power demand. We do not assume that the demand is generated by a known model. We follow a multiple time-scale approach for the stability analysis. It is shown that synchronization is achieved for the case of constant power demand, by showing that the system is exponentially stable. Furthermore, for the case of time-varying power demand, we show the error trajectories are ultimately bounded, and the synchronization error is proportional to an upper bound on the derivative of the time-varying power demand. We simulate the controller performance on a four area network which is equivalent to the IEEE New England 39-Bus system.

42 ENGINEERING↗
DOE OSTI2012

Power Systems Life Cycle Analysis Tool (Power LCAT) [Poster]

The Power LCA Tool shows environmental and cost results for NETL's LCAs of power systems, including fossil and wind power. In addition to reporting results for costs and emissions, it allows trade-off analysis between costs and emissions. It also allows the user to evaluate the sensitivity of results to changes in key parameters..

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
NASA NTRS1983

Automated distribution system management for multichannel space power systems

A NASA sponsored study of space power distribution system technology is in progress to develop an autonomously managed power system (AMPS) for large space power platforms. The multichannel, multikilowatt, utility-type power subsystem proposed presents new survivability requirements and increased subsystem complexity. The computer controls under development for the power management system must optimize the power subsystem performance and minimize the life cycle cost of the platform. A distribution system management philosophy has been formulated which incorporates these constraints. Its implementation using a TI9900 microprocessor and FORTH as the programming language is presented. The approach offers a novel solution to the perplexing problem of determining the optimal combination of loads which should be connected to each power channel for a versatile electrical distribution concept.

Fleck, G. W.↗
NASA NTRS1984

Control aspects of the Schuchuli Village stand-alone photovoltaic power system

A photovoltaic power system in an Arizona Indian village was installed. The control subsystem of this photovoltaic power system was analyzed. The four major functions of the control subsystem are: (1) voltage regulation; (2) load management; (3) water pump control; and (4) system protection. The control subsystem functions flowcharts for the control subsystem operation, and a computer program that models the control subsystem are presented.

Groumpos, P. P.↗
NASA NTRS2019

Maturation of Dynamic Power Convertors for Radioisotope Power Systems

Dynamic Radioisotope Power Systems (DRPS) are being developed by NASA's RPS Program in collaboration with the U.S. Department of Energy (DOE) for space science and exploration missions. A development effort is currently underway to mature dynamic power convertors for infusion into a potential future flight generator. This convertor maturation effort was formulated by the RPS Program at NASA Headquarters based on successful maturation models and utilizes expertise from agency technology and mission centers to support requirements development and technology assessments. The effort is being executed by Glenn Research Center's Dynamic Radioisotope Power Systems (DRPS) project and the Thermal Energy Conversion Branch. The Dynamic Power Convertor (DPC) contracts consist of three phases to enable design, fabrication, and independent assessment after delivery to the government. The contracts are intended to gather data on candidate dynamic conversion technologies to fill knowledge gaps, support assessments of dynamic conversion technologies, and elicit generator requirements. The SRG-110 (Stirling Radioisotope Generator) and ASRG (Advanced Stirling Radioisotope Generator) flight development projects provided Stirling convertor demonstration units and engineering models to verify and validate convertors against performance specifications and mission requirements. These units utilize temperature resistance materials and non-contacting bearings to demonstrate wear-free, long-life operation. This maturation effort builds on past lessons learned and new requirements focused on demonstrating convertor robustness to critical environments meant to stress key aspects of each convertor within the margins of the design. This effort seeks to realize the full potential of dynamic power conversion technologies for NASA's space science and exploration missions.

Wilson, Scott↗
DOE OSTI2010

Design of isolated renewable hybrid power systems

Isolated electrical power generating units can be used as an economically viable alternative to electrify remote villages where grid extension is not feasible. One of the options for building isolated power systems is by hybridizing renewable power sources like wind, solar, micro-hydro, etc. along with appropriate energy storage. A method to optimally size and to evaluate the cost of energy produced by a renewable hybrid system is proposed in this paper. The proposed method, which is based on the design space approach, can be used to determine the conditions for which hybridization of the system is cost effective. The simple and novel methodology, proposed in this paper, is based on the principles of process integration. It finds the minimum battery capacity when the availability and ratings of various renewable resources as well as load demand are known. The battery sizing methodology is used to determine the sizing curve and thereby the feasible design space for the entire system. Chance constrained programming approach is used to account for the stochastic nature of the renewable energy resources and to arrive at the design space. The optimal system configuration in the entire design space is selected based on the lowest cost of energy, subject to a specified reliability criterion. The effects of variation of the specified system reliability and the coefficient of correlation between renewable sources on the design space, as well as the optimum configuration are also studied in this paper. The proposed method is demonstrated by designing an isolated power system for an Indian village utilizing wind-solar photovoltaic-battery system. (author)

14 SOLAR ENERGY↗