Search NASA⌕ Search

SEARCH · Search NASA

Results for “contingency control”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

Step 1: Human System Integration (HSI) FY05 Pilot-Technology Interface Requirements for Contingency Management

This document involves definition of technology interface requirements for Contingency Management. This was performed through a review of Contingency Management-related, HSI requirements documents, standards, and recommended practices. Technology concepts in use by the Contingency Management Work Package were considered. Beginning with HSI high-level functional requirements for Contingency Management, and Contingency Management technology elements, HSI requirements for the interface to the pilot were identified. Results of the analysis describe (1) the information required by the pilot to have knowledge of system failures and associated contingency procedures, and (2) the control capability needed by the pilot to obtain system status and procedure information. Fundamentally, these requirements provide the candidate Contingency Management technology concepts with the necessary human-related elements to make them compatible with human capabilities and limitations. The results of the analysis describe how Contingency Management operations and functions should interface with the pilot to provide the necessary Contingency Management functionality to the UA-pilot system. Requirements and guidelines for Contingency Management are partitioned into four categories: (1) Health and Status and (2) Contingency Management. Each requirement is stated and is supported with a rationale and associated reference(s).

Source record↗
NASA NTRS1991

Dynamics and control of hypersonic vehicles - The integration challenge for the 1990's

The dynamic characteristics of hypersonic vehicles are reviewed, with special attention to the interactions between the airframe, engine, and structural dynamics. Based on a preliminary investigation of the dynamics of a generic vehicle configuration similar to the X-30 with Scramjet propulsion, an assessment of these interactions is presented. The control effectors include aerodynamic pitch-control surfaces, as well as engine fuel flow and diffuser area ratio. The study configuration is statically instable in pitch, and exhibits strong airframe/engine/elastic coupling in the attitude dynamics and engine responses. This strong coupling will require a highly integrated airframe-engine control system, and the performance of the attitude control system will be contingent upon the ability to adequately deal with the structural aeroelastic response and engine dynamics.

Schmidt, David K.↗
NASA NTRS2012

Orion Flight Test Architecture Benefits of MBSE Approach

Exploration Flight Test 1 (EFT-1) is an unmanned first orbital flight test of the Multi Purpose Crew Vehicle (MPCV) Mission s purpose is to: Test Orion s ascent, on-orbit and entry capabilities Monitor critical activities Provide ground control in support of contingency scenarios Requires development of a large scale end-to-end information system network architecture To effectively communicate the scope of the end-to-end system a model-based system engineering approach was chosen.

Exploration Flight Test 1 (EFT-1)↗
NASA NTRS2013

Optimal Propellant Maneuver Flight Demonstrations on ISS

In this paper, first ever flight demonstrations of Optimal Propellant Maneuver (OPM), a method of propulsive rotational state transition for spacecraft controlled using thrusters, is presented for the International Space Station (ISS). On August 1, 2012, two ISS reorientations of about 180deg each were performed using OPMs. These maneuvers were in preparation for the same-day launch and rendezvous of a Progress vehicle, also a first for ISS visiting vehicles. The first maneuver used 9.7 kg of propellant, whereas the second used 10.2 kg. Identical maneuvers performed without using OPMs would have used approximately 151.1kg and 150.9kg respectively. The OPM method is to use a pre-planned attitude command trajectory to accomplish a rotational state transition. The trajectory is designed to take advantage of the complete nonlinear system dynamics. The trajectory choice directly influences the cost of the maneuver, in this case, propellant. For example, while an eigenaxis maneuver is kinematically the shortest path between two orientations, following that path requires overcoming the nonlinear system dynamics, thereby increasing the cost of the maneuver. The eigenaxis path is used for ISS maneuvers using thrusters. By considering a longer angular path, the path dependence of the system dynamics can be exploited to reduce the cost. The benefits of OPM for the ISS include not only reduced lifetime propellant use, but also reduced loads, erosion, and contamination from thrusters due to fewer firings. Another advantage of the OPM is that it does not require ISS flight software modifications since it is a set of commands tailored to the specific attitude control architecture. The OPM takes advantage of the existing ISS control system architecture for propulsive rotation called USTO control mode1. USTO was originally developed to provide ISS Orbiter stack attitude control capability for a contingency tile-repair scenario, where the Orbiter is maneuvered using its robotic manipulator relative to the ISS. Since 2005 USTO has been used for nominal ISS operations.

Bhatt, Sagar↗
NASA NTRS2019

Autonomous Operating System (AOS)

The Autonomy Operating System (AOS) is a software system that enables core capabilities for the autonomous operations for an unmanned aircraft. It is based on the NASA cFS system and provides a higher-level layer of infrastructure and applications for the execution of flight plans, natural-language communication with Air Traffic Control, Diagnostics, Prognostics, and contingency planning.

Lowry, Michael R.↗
DOE OSTI2026

Mitigating Data Center Impact on Grid Stability: A Coordinated Control Strategy Using Verrus StabiliGrid Architecture

Large data centers, which now represent a significant and growing share of the total U.S. grid load, can inadvertently destabilize the electrical grid when they disconnect simultaneously during brief voltage disturbances. The July 10, 2024, Eastern Interconnection incident, in which a sub-100-millisecond transmission fault triggered the cascading loss of approximately 1,500 MW of data center load, illustrates this vulnerability. While commercial battery energy storage systems (BESS) deployed in data centers provide device-level fault ride-through per IEEE 1547, they lack coordination with facility protection logic and uninterruptible power supplies (UPS), limiting their effectiveness as grid-stabilizing assets. This report presents the Verrus StabiliGrid architecture, a coordinated control framework that integrates BESS, UPS, and point-of-interconnection (POI) protection settings to enable data centers to ride through both undervoltage and overvoltage grid contingencies without disconnecting. The four-step strategy encompasses: (1) high-resolution power quality monitoring to detect the grid state during events such as undervoltage, overvoltage, underfrequency, and overfrequency; (2) POI protection settings that allow for extended ride-through and grid-connected operation during grid contingencies; (3) grid state-driven autonomous dispatch of assets to improve grid resilience by reducing power draw during undervoltage or absorbing more power during overvoltage events; and (4) coordinated post-recovery dispatch of data center assets to restore firm load to pre-contingency levels. Validated through controller-hardware-in-the-loop (C-HIL) simulations at the National Laboratory of the Rockies, results show grid import restoration to pre-fault levels within 100 milliseconds of voltage recovery. This work advances the ability of data centers to transition from passive, disturbance-sensitive loads to active participants in grid stability, a capability increasingly required by emerging NERC and ERCOT regulatory frameworks.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS1972

Apollo experience report: The application of a computerized visualization capability to lunar missions

The development of a computerized capability to depict views from the Apollo spacecraft during a lunar mission was undertaken before the Apollo 8 mission. Such views were considered valuable because of the difficulties in visualizing the complex geometry of the Earth, Moon, Sun, and spacecraft. Such visualization capability originally was desired for spacecraft attitude verification and contingency situations. Improvements were added for later Apollo flights, and results were adopted for several real time and preflight applications. Some specific applications have included crewmember and ground control personnel familiarization, nominal and contingency mission planning, definition of secondary attitude checks for all major thrust maneuvers, and preflight star selection for navigation and for platform alinement. The use of this computerized visualization capability should prove valuable for any future space program as an aid to understanding the geometrical relationships between the spacecraft and the celestial surroundings.

Hyle, C. T.↗
NASA NTRSDate not supplied

Optimizing Consumable Gas Tank Usage while Maintaining Emergency Reserves Between Two Pressure Control Systems on Gateway

Two of NASA’s Lunar Space Station (Gateway) modules, the Habitation and Logistics Outpost (HALO) and International Habitat (IHAB) contain a pressure control system (PCS) that is used to supply Nitrogen (N2) and Oxygen (O2) to maintain a habitable environment within Gateway, with only one of the PCS active at any given time. To protect the crew during a contingency that is affecting pressure control and therefore gas consumables, Gateway is required to have sufficient amount of reserve consumable gas across the entire habitable Gateway stack of modules until the gas can be replenished by crew changing out a gas tank. This will occur in a non-contingency setting either on the current mission or on the next mission. To access the stack reserve Gateway features a Nitrogen Oxygen Transfer System (NOTS) between HALO and IHAB that allows each module’s PCS to access the gas tanks in the other module. The PCS designs are different between the two modules and lack interchangeable tanks so which module has active PCS must be accounted for in logistics planning. This paper describes the logistics resupply planning analysis used to determine the most efficient use of the tanks within each PCS, and a method for switching which module is active for PCS while maintaining the stack reserve that preserves enough gas to cover contingency cases.

Rachel Anne Sturtz↗
DOE OSTI2021

Transactive Energy Rationing in an Islanded Electric Power System

A battery energy storage system (BESS) has been installed on Nantucket Island to provide service continuity during the N-1 contingency of partial electricity supply interruption from the mainland. During the N-2 contingency of complete interruption from the mainland, most of the loads will have to be disconnected so that a combustion gas turbine (CTG) can supply critical facilities. This work proposes an alternative transactive rationing mechanism that would provide some service to all of the loads, and still fully serve the critical loads, through market-based control during the N-2 contingency. A BESS operating strategy is proposed that would enhance the transactive rationing mechanism. The necessary enabling changes to communication systems, controls and utility tariffs are discussed, along with some ancillary benefits.

transactive energy, power distribution, energy sto↗
DOE OSTI2022

Study of Inverter Control Strategies on the Stability of Low-Inertia Microgrid Systems

This paper investigates the stability of low-inertia microgrid systems with two control strategies that have different percentages of grid-forming (GFM) inverters. The first control strategy has approximately 50% GFM inverters, and all the battery inverters are working in GFM control mode. Originally, the second control strategy has approximately 10% GFM inverters, with only two battery inverters working in GFM control mode and the rest working in grid-following (GFL) PQ control mode based on current control, which cannot stabilize the microgrid system. Then, the second control strategy is modified to change the GFM inverters from droop control to isochronous control and the GFL battery inverters from traditional current control to voltage control for power control. Both control strategies can maintain system stability; however, the first control strategy can better handle contingency events. The study indicates that 1) a microgrid system with a higher percentage of GFM inverters has better stability; and 2) a microgrid with a lower percentage of GFM inverters can have poor stability, but improved control strategies in inverters can improve system stability. This study improves the understanding of how different percentages of GFM inverters and inverter control strategies affect the system stability of low-inertia microgrids.

droop control↗
DOE OSTI2022

Study of Inverter Control Strategies on the Stability of Low-Inertia Microgrid Systems: Preprint

This paper investigates the stability of low-inertia microgrid systems with two control strategies that have different percentages of grid-forming (GFM) inverters. The first control strategy has approximately 50% GFM inverters, and all the battery inverters are working in GFM control mode. Originally, the second control strategy has approximately 10% GFM inverters, with only two battery inverters working in GFM control mode and the rest working in grid-following (GFL) PQ control mode based on current control, which cannot stabilize the microgrid system. Then, the second control strategy is modified to change the GFM inverters from droop control to isochronous control and the GFL battery inverters from traditional current control to voltage control for power control. Both control strategies can maintain system stability; however, the first control strategy can better handle contingency events. The study indicates that 1) a microgrid system with a higher percentage of GFM inverters has better stability; and 2) a microgrid with a lower percentage of GFM inverters can have poor stability, but improved control strategies in inverters can improve system stability. This study improves the understanding of how different percentages of GFM inverters and inverter control strategies affect the system stability of low-inertia microgrids.

droop control↗
DOE OSTI2022

Study of Inverter Control Strategies on the Stability of Low-Inertia Microgrid Systems

This paper investigates the stability of low-inertia microgrid systems with two control strategies that have different percentages of grid-forming (GFM) inverters. The first control strategy has approximately 50% GFM inverters, and all the battery inverters are working in GFM control mode. Originally, the second control strategy has approximately 10% GFM inverters, with only two battery inverters working in GFM control mode and the rest working in grid-following (GFL) PQ control mode based on current control, which cannot stabilize the microgrid system. Then, the second control strategy is modified to change the GFM inverters from droop control to isochronous control and the GFL battery inverters from traditional current control to voltage control for power control. Both control strategies can maintain system stability; however, the first control strategy can better handle contingency events. The study indicates that 1) a microgrid system with a higher percentage of GFM inverters has better stability; and 2) a microgrid with a lower percentage of GFM inverters can have poor stability, but improved control strategies in inverters can improve system stability. This study improves the understanding of how different percentages of GFM inverters and inverter control strategies affect the system stability of low-inertia microgrids.

droop control↗
NASA NTRS2007

Rapid Contingency Simulation Modeling of the NASA Crew Launch Vehicle

The NASA Crew Launch Vehicle is a two-stage orbital launcher designed to meet NASA's current as well as future needs for human space flight. In order to free the designers to explore more possibilities during the design phase, a need exists for the ability to quickly perform simulation on both the baseline vehicle as well as the vehicle after proposed changes due to mission planning, vehicle configuration and avionics changes, proposed new guidance and control algorithms, and any other contingencies the designers may wish to consider. Further, after the vehicle is designed and built, the need will remain for such analysis in the event of future mission planning. An easily reconfigurable, modular, nonlinear six-degree-of-freedom simulation matching NASA Marshall's in-house high-fidelity simulator is created with the ability to quickly perform simulation and analysis of the Crew Launch Vehicle throughout the entire launch profile. Simulation results are presented and discussed, and an example comparison fly-off between two candidate controllers is presented.

Betts, Kevin M.↗
DOE OSTI2024

A Comprehensive Strategy for Grid Forming Control in DC Coupled Photovoltaic and Battery Energy Storage Inverters

This paper presents an integrated DC-DC and DCAC grid-forming control strategy for DC-coupled photovoltaic (PV) plus battery energy storage systems, considering the effect of DC link voltage variations caused by direct PV connections. A power reference algorithm determines power distribution between the PV and battery to the grid while observing device power ratings to prevent the over-rating of components and keep the battery's state of charge within an acceptable range. The simulated utility-scale model in MATLAB/Simulink illustrates its ability against extreme phase angle variation contingencies in the grid while controlled through grid-forming control with a fast dynamic on DC link voltage. The simulation results confirm the effectiveness of the proposed control in integrating PV plus battery configurations with grid forming control and maintaining reliable grid operation under severe grid disturbances.

battery, boost, control, energy storage, grid form↗
NASA NTRS2014

NASA's UAS Integration into the NAS: A Report on the Human Systems Integration Phase 1 Simulation Activities

In 2011 the National Aeronautics and Space Administration (NASA) began a five-year Project to address the technical barriers related to routine access of Unmanned Aerial Systems (UAS) in the National Airspace System (NAS). Planned in two phases, the goal of the first phase was to lay the foundations for the Project by identifying those barriers and key issues to be addressed to achieve integration. Phase 1 activities were completed two years into the five-year Project. The purpose of this paper is to review activities within the Human Systems Integration (HSI) subproject in Phase 1 toward its two objectives: 1) develop GCS guidelines for routine UAS access to the NAS, and 2) develop a prototype display suite within an existing Ground Control Station (GCS). The first objective directly addresses a critical barrier for UAS integration into the NAS - a lack of GCS design standards or requirements. First, the paper describes the initial development of a prototype GCS display suite and supporting simulation software capabilities. Then, three simulation experiments utilizing this simulation architecture are summarized. The first experiment sought to determine a baseline performance of UAS pilots operating in civil airspace under current instrument flight rules for manned aircraft. The second experiment examined the effect of currently employed UAS contingency procedures on Air Traffic Control (ATC) participants. The third experiment compared three GCS command and control interfaces on UAS pilot response times in compliance with ATC clearances. The authors discuss how the results of these and future simulation and flight-testing activities contribute to the development of GCS guidelines to support the safe integration of UAS into the NAS. Finally, the planned activities for Phase 2, including an integrated human-in-the-loop simulation and two flight tests are briefly described.

National Airspace System↗
NASA NTRS2001

Smarter Software For Enhanced Vehicle Health Monitoring and Inter-Planetary Exploration

The existing philosophy for space mission control was born in the early days of the space program when technology did not exist to put significant control responsibility onboard the spacecraft. NASA relied on a team of ground control experts to troubleshoot systems when problems occurred. As computing capability improved, more responsibility was handed over to the systems software. However, there is still a large contingent of both launch and flight controllers supporting each mission. New technology can update this philosophy to increase mission assurance and reduce the cost of inter-planetary exploration. The advent of model-based diagnosis and intelligent planning software enables spacecraft to handle most routine problems automatically and allocate resources in a flexible way to realize mission objectives. The manifests for recent missions include multiple subsystems and complex experiments. Spacecraft must operate at longer distances from earth where communications delays make earthbound command and control impractical. NASA's Ames Research Center (ARC) has demonstrated the utility of onboard diagnosis and planning with the Remote Agent experiment in 1999. KSC has pioneered model-based diagnosis and demonstrated its utility for ground support operations. KSC and ARC are cooperating in research to improve the state of the art of this technology. This paper highlights model-based reasoning applications for Moon and Mars missions including in-situ resource utilization and enhanced vehicle health monitoring.

Larson, William E.↗
NASA NTRS1969

Apollo life-support and protective systems

Apollo extravehicular mobility unit /EMU/ system developed from Gemini EVA system with improved thermal control and mobility to support contingency extravehicular transfer in emergency

Faget, M. A.↗
NASA NTRS1989

Sensitivity of propulsion system selection to Space Station Freedom performance requirements

The selection of the propulsion system for the Space Station (SS) is reassessed. The propulsion system consists of two distinct elements. The first of these combusts gaseous oxygen and hydrogen produced from water electrolysis, to maintain the SS altitude and perform higher thrust maneuvers for backup attitude control, collision avoidance, and other contingencies. The second consists of gas resistojets, which augment altitude maintenance. The results of a parametric comparison of the life cycle costs of this electrolysis/resistojet propulsion with those of other system options, carried out over a range of probable performance requirements, confirmed the baseline superiority of the SS propulsion system for most anticipated conditions. However, relative costs among impulse requirements vary so much that major changes in the design conditions may warrant implementation of another system (such as hydrazine with water resistojets).

Schmidt, George R.↗