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Results for “Distributed 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.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Electrified vehicle DC power conversion with distributed control

An electrified vehicle has a battery pack comprising series-connected battery units providing a main voltage. To supply a lower voltage bus equally from all battery units, a plurality of DC/DC converters are powered by respective units and have their outputs in parallel. A central module has an outer loop controller generating a target current to regulate the bus voltage to a predetermined voltage and has an allocator distributing the target current into a plurality of allocated current commands according to respective states of charge of the battery units. A plurality of local controllers each adjusts a current of a respective DC/DC converter. Each local controller receives a respective allocated current command as a respective feedforward control variable. Each local controller uses an error between the bus voltage and the predetermined voltage to be integrated as a respective feedback control variable only when the error is above a threshold.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2016

Numerical modeling of heterogeneous asperity distributions controlling the growth of shear rupture on a frictional fault

Copyright 2016 ARMA, American Rock Mechanics Association. A better understanding of the strength distributions and the seismic response of asperities failing within a cohesive (or breakdown) region of the growing shear rupture is important in many engineering disciplines, such as, hydraulic fracture and induced seismicity. In the laboratory, a fault is experimentally modeled by a 400 mm × 80 mm × 12 mm PMMA slider sheared across a large PMMA base plate. A pressure-sensitive film was employed to localize and size, and measure normal stress upon contact junctions. Moments prior to rapid sliding, multiple discrete and localized dynamic events (or foreshocks) were observed at a section of the fault that exhibited a sparse to dense transition in asperity distribution. Experiments showed that foreshocks occurred as the crack (rupture front) moved into the resistive patch of densely distributed asperities. We use the results of pressure sensitive film asperity measurements to develop a heterogeneous finite element (FE) model that studies the effect of asperities within the cohesive region have on the expanding shear crack. Slip accumulated heterogeneously during the loading cycle due to the non-uniform distribution of asperities. We study the constitutive behavior of a frictional interface where local slip is determined by the asperities and their ability to communicate elastically. A foreshock (Mw -7.4) was simulated in a quasi-static manner by instantaneoulsy removing an asperity contact during the loading cycle. The foreshock increased shear stress perturbations to neighboring regions up to distances of ~ 10 to 15 source radii.

Selvadurai, PA↗
DOE OSTI2025

Distributed Control and Optimization of Virtual Inertia in Power Systems

The integration of renewable energy sources into power grids through inverter-based resources (IBRs) reduces system inertia, leading to faster frequency dynamics and potential grid instability. This paper proposes a distributed, consensus-based approach for the real-time control and optimization of inertia sources during system disturbances, enhancing both system stability and economic performance. Furthermore, we integrate this approach with the traditional inertia placement problem, demonstrating its suitability for existing frameworks. We validate its effectiveness in a 4-bus test system and a two-area 8-bus test system, showcasing its potential for scalable, dynamic inertia management in low-inertia grids.

Yadav, Ajay [ORNL] (ORCID:000000016111881X)↗
DOE OSTI2021

Distributed control of electric power grids

A method for determining power output levels of a plurality of nodes in an electric power system includes receiving, at a first node of the plurality of nodes, voltage information and multipliers of all neighboring nodes of the first node within the electric power system, determining, by the first node, a local power generation and a local voltage using the voltage information and the multipliers of the neighboring nodes and distributing the local power generation and the local voltage to the neighboring nodes, determining, by the first node, an estimated voltage of each of the neighboring nodes and distributing the estimated voltage to each of the neighboring nodes, and updating, by the first node, a local multiplier using the voltage information received from the neighboring nodes and the estimated voltage of each of the neighboring nodes determined by the node.

Ghosh, Soumyadip↗
DOE OSTI2019

Decentralized Signal Processing and Distributed Control of Collaborative Autonomous Networks (17-ERD-101 LDRD Final Report)

Intelligent autonomous sensor networks, often comprised of large numbers of sensors, must be capable of jointly exploiting data collected at each agent in the network, and using that data to optimize their future actions towards multiple mission objectives. Centralized signal processing and optimization solutions process all data and determine all future actions at a single agent, and the resulting information and commands are disseminated back to the network. The communications bandwidth this requires and the single point of failure the central agent represents often make these solutions untenable for national security applications. In this project, several fundamental algorithms for solving both the decentralized signal processing and network optimization were developed, as well as simulation software to validate the results of these algorithms at scale. Specifically, novel algorithms for Bayesian decentralized estimation and decentralized detection and optimization based on the alternating direction method of multipliers (ADMM) were developed for autonomous sensor networks and published in the literature. The first large scale simulation of autonomous sensor networks (1000 agents) was conducted on this project, validating the performance of the developed algorithms. These algorithms and simulation tools are critical components of any decentralized autonomous network and have current and future national security applications, including distributed sensor networks for detection, estimation, and tracking problems, and large decentralized cyber-physical infrastructure such as the power grid.

42 ENGINEERING↗
DOE OSTI2025

Mechanistic Insights into Adsorptive and Catalytic Reactions from Controllable Distributions of Metal Cations (Pd, Pt, Ni, Cr, Cu) as [M‐OH] +1 /1Al or M +2 /2Al in Zeolites

Anchoring divalent metal ions in the same zeolite framework with similar Si/Al ratio selectively as zeolite-bound M +2 or [M +2 -OH] +1 cationic species enables critical comparison of the species’ intrinsic reactivity for industrially and fundamentally relevant reactions. H-BEA zeolites with similar Si/Al ratios but differing framework Al siting were used to anchored multiple divalent metal cations (Ni, Pd, Pt, Cr, Cu) in the zeolite micropores. State-of-the-art infrared (IR) spectroscopy, electron paramagnetic resonance (EPR) measurements, including two-dimensional pulsed HYSCORE EPR, extended X-ray absorption fine structure (EXAFS), and density functional theory (DFT) calculations together provide unambiguous evidence for the selective formation of divalent metal cations as M +2 /2Al species (for H-BEA prepared in the conventional hydroxide media), and [M +2 OH] +1 /1Al species for H-BEA prepared in HF. Solid-state proton-decoupled triple-quantum magic-angle spinning (3Q MAS) NMR measurements confirmed contrasting Al distributions in the two H-BEA zeolites, which led to a contrasting divalent cation speciation. The reactivities of the two cationic species were explored for catalytic and adsorptive applications in both organometallic homogeneous and heterogeneous catalysis. This work demonstrates their divergent reactivity in ethylene dimerization, ethylene oxidation (Wacker process), selective catalytic reduction (SCR) of NO, NO adsorption, and methane oxidation. Both M +2 /2Al and [M +2 OH] +1 /1Al cations are both active for ethylene dimerization, but [M +2 OH] +1 /1Al species show higher reaction rates for each Pd, Ni, Pt. [M +2 OH] +1 /1Al is active for acetaldehyde formation in Wacker ethylene oxidation. A new active site for ethylene oligomerization is proposed that possesses a terminal OH group (Cr-OH) in Phillips catalysts evident by a nearly inactive isolated Cr +2 /2Al species that contrast an active Cr─OH motif.

Divalent metal cations in a zeolite↗
DOE OSTI2019

Asymmetric Dual Sensor Latency in Distributed Control

Considerable geographical separation between various phasor measurement unit sensor suites used in the wide-area damping control architecture results in time delays with varying steady-state and stochastic components. The consequences of asymmetric latent sensors used in a standard feedback configuration are presented, indicating that asymmetry of the delay provides not only a previously suspected modification to the argument of the loop transmission function, but also a potentially substantial impact on its modulus. Under particular delay configurations, the controller may experience the introduction of varying crossovers in the loop transmission, resulting in a shifting of control bandwidth and previously unconsidered (in)stability characteristics (e.g., alteration of relative stability margins). With consideration to the theoretical results provided, the optimal sensor location based on delay characteristics is provided. Finally, results of the study indicate that it is most frequently best practice to act on the most current sample in the feedback channel, rather than wait for precise time alignment of the delayed sensor.

42 ENGINEERING↗
DOE OSTI2019

LCLS-II Cryomodule and Cryogenic Distribution Control

The new superconducting Linear Coherent Light Source (LCLS-II) at the SLAC National Accelerator Laboratory will be an upgrade to LCLS, the world’s first hard X-ray free-electron laser. LCLS-II is in an advanced stage of construction with equipment for both Cryoplants as well as more than half of the 37 cryomodules onsite. Jefferson Lab (JLab) is a partner lab responsible for building half of the LCLS-II cryomodules. Hence the Low Energy Recirculation Facility (LERF) at JLab was used to stage and test LCLS-II cryomodules before shipping them to SLAC. LERF was set up to test two cryomodules at a time. LERF used LCLS-II cryogenic controls instrumentation racks, Programmable Logic Controllers (PLC) controls and Experimental Physics and Industrial Control System (EPICS) Input/Output Controllers (IOCs) with the intention to use the LERF setup to check-out and verify cryogenic controls for LCLS-II. The cryogenic controls first utilized at LERF would then be replicated for controlling all 37 cryomodules via an EPICS user interface. This paper discusses the cryogenic controls currently developed for implementation in the LCLS-II project.

43 PARTICLE ACCELERATORS↗