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DOE OSTI2022

Energy management system, method of controlling one or more energy storage devices and control unit for one or more power storage units

Systems, methods and apparatuses are provided for reducing peak energy demand and to smooth intermittent energy profiles from onsite variable energy sources and loads. Some embodiments use system level and device level analysis and optimization to adaptively adjust the operation of a behind the meter energy storage (BMES) to smooth out energy generation variabilities and follow a reference load signal, including at short time resolutions.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

DOE OSTI2020

A Station-hybrid HVDC System Structure and Control Strategies for Cross-seam Power Transmission

Cross-seam high voltage DC (HVDC) transmission in the United States can provide an efficient and flexible bulk power delivery highway between the interconnections. Recent studies have shown significant economic benefits of cross-seam HVDC transmission systems by taking the advantages of load diversity, frequency response, renewable energy diversity, and energy arbitrage in the different interconnections. This paper introduces a station-hybrid system scheme for cross-seam interconnections. Here, the proposed station-hybrid system combines the advantages of line commutated converter (LCC) and voltage source converter (VSC) technologies, thus enabling reliable and flexible bidirectional power flows across the interconnections. Control strategies of the station-hybrid system are investigated with a focus on power flow reversal control under normal operation conditions and grid support control under emergency conditions. The feasibility and effectiveness of the proposed station-hybrid system and corresponding control strategies are verified by simulations in PSCAD/EMTDC.

Station-hybrid system↗

DOE OSTI2021

Overview of the results from divertor experiments with attached and detached plasmas at Wendelstein 7-X and their implications for steady-state operation

Abstract Wendelstein 7-X (W7-X), the largest advanced stellarator, is built to demonstrate high power, high performance quasi-continuous operation. Therefore, in the recent campaign, experiments were performed to prepare for long pulse operation, addressing three critical issues: the development of stable detachment, control of the heat and particle exhaust, and the impact of leading edges on plasma performance. The heat and particle exhaust in W7-X is realized with the help of an island divertor, which utilizes large magnetic islands at the plasma boundary. This concept shows very efficient heat flux spreading and favourable scaling with input power. Experiments performed to overload leading edges showed that the island divertor yields good impurity screening. A highlight of the recent campaign was a robust detachment scenario, which allowed reducing power loads even by a factor of ten. At the same time, neutral pressures at the pumping gap entrance yielded the particle removal rate close to the values required for stable density control in steady-state operation.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2025

Mixing-Controlled Combustion of Ethanol Enabled by Prechamber Ignition (PC-MCC): A Preliminary Experimental Demonstration

This experimental study presents preliminary investigations of prechamber-enabled mixing-controlled combustion (PC-MCC) at −2 bar brake mean effective pressure (BMEP) and 2200 rpm with fuel-grade ethanol (E98). Experimental results are conducted on a prechamber retrofitted single-cylinder Caterpillar C9.3B test engine. First, a series of prechamber-only experiments were conducted with a motored engine to evaluate the salient combustion trends in response to relevant prechamber operating parameters. Under firing conditions, the prechamber operating strategy was assessed with respect to the impact on ignition assistance of direct-injected E98 and overall engine performance. The preliminary results indicate the jet-induced ignition process is robust and prompts diffusion combustion of E98 at diesel-like boundary conditions. Here, the effect of external exhaust gas recirculation (EGR) on the residual tolerance of the prechamber combustion process was also investigated and showed stable combustion in both the main chamber and prechamber up to 30% EGR. Experiments were also conducted with the stock diesel engine for baseline comparison. At matched combustion phasing, mixing-controlled combustion of ethanol enabled by prechamber ignition was able to achieve heightened gross thermal efficiency while simultaneously reducing NOx and practically eliminating smoke emissions relative to diesel combustion. In addition, the covariance of load and standard deviation of combustion phasing was diesel-like and less than 2% and 1 CAD, respectively.

PC-MCC↗

DOE OSTI2021

Basket Modification Concepts for Disposal Reactivity Control of Dual Purpose Canisters

This report documents work performed supporting the US Department of Energy (DOE) Office of Nuclear Energy (NE) Spent Fuel and Waste Disposition (SFWD), Spent Fuel and Waste Science and Technology, under work breakdown structure element 1.08.01.03.05, “Direct Disposal of Dual Purpose Canisters.” In particular, this report fulfills milestone M3SF-21OR010305125, “DPC criticality analysis with fuel/basket modification,” within work package SF-21OR01030512, “DPC Reactivity and Criticality Modeling—ORNL.” This report uses three of the most reactive canisters that have been analyzed to-date using UNFST&DARDS to examine the performance of three potential reactivity suppression technologies under disposal conditions. Three already loaded canisters were analyzed using as-loaded contents including TSC-37 and MPC-32 pressurized water reactor (PWR) dual-purpose canisters (DPCs) and the MPC-89 DPCs. The reactivity suppression technologies considered were the B4C-filled disposal control rod assembly (DCRA) and the advanced neutron absorber (ANA)–based chevron insert for the PWR canisters and the ANA-based fuel channel replacement absorber for the MPC-89. For each combination of absorber concept and DPC, various insert patterns and absorber material concentrations were considered. The results of the analysis show that the DCRA concept has promise for providing reactivity hold-down for PWR DPCs, and the ANA fuel channel replacement absorber has promise for providing reactivity holddown in BWR DPCs. The ANA chevron basket insert showed mixed results, providing sufficient reactivity hold-down in the lower reactivity canister, but failing to do so in the higher reactivity canister considered herein.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2020

Adaptive PV Frequency Control Strategy Based on Real-time Inertia Estimation

The declining cost of solar Photovoltaics (PV) generation is driving its worldwide deployment. As conventional generation with large rotating masses is being replaced by renewable energy such as PV, the power system’s inertia will be affected. As a result, the system’s frequency may vary more dramatically in the case of a disturbance, and the frequency nadir may be low enough to trigger protection relays such as under-frequency load shedding. The existing frequency-watt function mandated in power inverters cannot provide grid frequency support in a loss-of-generation event, as PV plants usually do not have power reserves. Here, a novel adaptive PV frequency control strategy is proposed to reserve the minimum power required for grid frequency support. A machine learning model is trained to predict system frequency response under varying system conditions, and an adaptive allocation of PV headroom reserves is made based on the machine learning model as well as real-time system conditions including inertia. Case studies show the proposed control method meets the frequency nadir requirements using minimal power reserves compared to a fixed headroom control approach.

14 SOLAR ENERGY↗

DOE OSTI2020

Intrinsic size dependent plasticity in BCC micro-pillars under uniaxial tension and pure torsion

The mechanical behavior of submicron body-centered cubic (BCC) micro-pillars is investigated by three-dimensional dislocation dynamics (DD) simulations to better understand the governing mechanisms for size dependent plasticity under uniaxial tension and pure torsion. A formula is developed to compute the incremental plastic twist due to dislocation motion in DD simulations. The DD simulations show that different dislocation microstructures are created depending on the loading conditions, which leads to different size dependent mechanical behavior. While in tension plasticity is mainly governed by the kinetics of dislocation motion controlled partly by the surface dislocation sources, plastic flow in torsion is controlled by dislocation pile-ups associated with strain gradients. The simulation results also reveal a Bauschinger effect and plastic recovery under cyclic twist, which have been observed in recent experiments.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Maximum power point tracking for a multi-layered piezoelectric heel charger with a levered mechanism toward impact-based energy harvesting

The piezoelectric footstep energy harvester does not always work at its maximum power point when the external load is fixed, as the optimal load changes when the walking excitation alters. Thus, the harvesting efficiency is downgraded largely in real-life scenarios compared to in-lab experiments and theoretical or numerical predictions due to the mismatch between the actual load and the optimal load. To address this issue, the concept of Maximum Power Point Tracking (MPPT) is investigated in this paper and the circuit design is implemented for a multi-layered levered piezoelectric footstep energy harvester (heel charger). The proposed event-driven MPPT circuit interface with a customized buck converter aims to maximize the power gained from daily walking using the heel charger to power a fixed load, such as smart insole or shoes. The MPPT circuit design is conceptually simulated and then tested with the heel charger to further validate if it works at its maximum power point when the frequency of the input excitation alters. Results show that the extracted power from the heel charger connected to a fixed resistance load with MPPT implementation is improved up to 300% compared to the one without MPPT implementation in simulation and up to 180% in the experiment when connected to a fixed load. The difference between simulation and experimental results is due to the optimization of using voltage sources as the heel charger and the control signals (pulse width modulation) from the microcontroller in the simulation.

47 OTHER INSTRUMENTATION↗

DOE OSTI2020

Reversible plasmonic switching in a graphene nanoresonator loaded with a core – shell quantum dot

A model of an all-plasmonic switch based on a graphene waveguide integrated with a stub nanoresonator loaded with a quantum dot is considered. Using the full-wave numerical simulation, it is shown that successive on/off switching of the control surface plasmon – polariton wave at the input of the waveguide leads to a change in the phase of the signal plasmon – polariton wave in the nanoresonator by π. This causes reversible switching of the device operation regime – from almost complete blocking to stable transmission of the signal plasmon – polariton wave through the waveguide. The effect is implemented at rates of ∼0.5 THz for infrared electromagnetic waves localised in a device with a switching region of 40 × 20 nm. (paper)

36 MATERIALS SCIENCE↗

DOE OSTI2023

The JET hybrid scenario in Deuterium, Tritium and Deuterium-Tritium

The JET hybrid scenario has been developed from low plasma current carbon wall discharges to the record-breaking Deuterium-Tritium plasmas obtained in 2021 with the ITER-like Be/W wall. The development started in pure Deuterium with refinement of the plasma current, and toroidal magnetic field choices and succeeded in solving the heat load challenges arising from 37 MW of injected power in the ITER like wall environment, keeping the radiation in the edge and core controlled, avoiding MHD instabilities and reaching high neutron rates. The Deuterium hybrid plasmas have been re-run in Tritium and methods have been found to keep the radiation controlled but not at high fusion performance probably due to time constraints. For the first time this scenario has been run in Deuterium-Tritium (50:50). These plasmas were re-optimised to have a radiation-stable H-mode entry phase, good impurity control through edge T i gradient screening and optimised performance with fusion power exceeding 10 MW for longer than three alpha particle slow down times, 8.3 MW averaged over 5 s and fusion energy of 45.8 MJ.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2025

Microgrid Black Start Challenges: The Role of Grid-Forming Inverters

Grid-forming (GFM) inverters are becoming increasingly important for future power systems, particularly in establishing and restarting microgrids after blackouts. The use of GFM inverters enables microgrids to operate independently of utility power and provide key advantages over synchronous generators in black start scenarios, including rapid startup and stable voltage and frequency support for critical loads. However, inverter-driven black start introduces unique challenges and operational considerations. This article examines key challenges and solutions, emphasizing inverter design, control strategies, and microgrid system requirements. Drawing on analysis, simulation, and experimental results, this article highlights the central role of GFM inverters in ensuring reliable and resilient microgrid operations.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2022

Stochastic Strategic Participation of Active Distribution Networks With High-Penetration DERs in Wholesale Electricity Markets

With the increasing penetration of distributed energy resources (DERs), traditional distribution networks as load-serving entities in wholesale electricity markets, now evolve towards active distribution networks (ADNs) which can proactively participate in wholesale markets by optimally controlling the DERs in their networks. A stochastic bilevel optimization model is proposed in this paper for the strategic participation of ADNs and DERs to provide energy and grid services in wholesale electricity markets. The bilevel optimization model can capture the interactions between the ADN and the wholesale energy and ancillary service markets, considering the uncertainties of DERs in the ADN. In the upper-level model, the ADN makes optimal decisions on energy and reserve bidding considering the availability, uncertainties, and flexibility of DERs. The joint energy and reserve market-clearing of the independent system operator (ISO) is modeled as the lower-level problem. Using strong duality theory and Karush-Kuhn Tucker (KKT) conditions, the proposed bilevel optimization problem is reformulated as mathematical programming with equilibrium constraints (MPEC) problem and further converted into a computationally-solvable mixed-integer second-order-cone programming (MISOCP) model. The simulation results demonstrate the effectiveness of the model and the interactions between an ADN and wholesale electricity markets.

active distribution network↗

DOE OSTI2026

Dynamic Facade Dashboard v0.1.0

The dashboard is a useful tool for early-stage building design decision-making and communication, as it can help users quickly compare the energy and non-energy related performance of various automated, integrated facade systems using a library of pre-computed data. Users can explore the impacts of various design choices by selecting different facade glazing and shading systems, facade control strategies, and lighting control strategies across multiple climate zones. The dashboard instantly visualizes key metrics, including energy usage in HVAC and lighting, peak cooling and heating load, and daylight availability, allowing immediate trade-off analysis to optimize building efficiency and comfort.

Yu, Tammie [Lawrence Berkeley National Laboratory ↗

DOE OSTI2023

Citadels Final Report (GMLC 2.2.1: Citadels)

This is the final project report for the Grid Modernization Laboratory Consortium (GMLC) Resilient Distribution System (RDS) Citadels project. The primary goal of this GMLC project was to increase the operational flexibly of power systems by engaging microgrids distributedly, coordinated using consensus algorithms. The primary goal was successfully achieved. The primary goal was divided into three areas: Implement peer-to-peer control between microgrid controllers using the Open Field Message Bus (OpenFMB) approach; Develop and implement consensus algorithms on commercially available hardware that allows a group of microgrids to distributedly implement operational controls; Develop the architectures and controls to enable groups of microgrids to coordinate their operations to support the bulk power system during abnormal events, and end-use loads in the event the bulk power systems fail.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2025

Comparison of Nuclear Thermal Propulsion Reactor Cores Using Different Fuel Forms, Neutron Spectra, and Uranium Enrichments

A comparison of 300 MWt HEU and HALEU NTP cores using different fuel forms is presented to demonstrate trends and potentially inform fuel development. Compared to HEU, HALEU cores require additional in-core moderation. Beryllium was chosen as the reference in-core moderator material; metal hydrides may also be considered. Typical NTP fuel forms such as carbide and carbonitride solid solutions, carbide-graphite composites, CERMETs and CERCERs were considered together with less typical fuel forms such as UC and U metal. Be-moderated HALEU cores are heavier than HEU cores (1.9-2.7 and 0.9-2.0 metric tons, respectively). Furthermore, HALEU loading is very sensitive to the amount of in-core moderation which translates into tight fabrication tolerances. HALEU cores requires more reactivity control mechanisms than HEU cores to compensate for temperature feed-back. Using enrichments only slightly above HALEU (e.g., 25%) may provide a compromise between the administrative preference for using HALEU and the engineering preference for simplifying the reactor systems by, for example, not using in-core moderators.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2022

Modular Control Architecture for Scalable, Resilient, and Cybersecure Microgrids Test Results [Mojave firmware 1.09 FW valuation]

This quick note outlines what we found after our conversion with you and your team. As suggested, we loaded 1547-2003 source requirements document (SRD) and then went back and loaded 1547-2018 SRD. This did result in implementing the new 1547-2018 settings. This short report focuses on the frequency-watt function and shows a couple of screen shots of the parameter settings via the Mojave HMI interface and plots of the results of the inverter with FW function enabled in both default and most aggressive settings response to frequency events. The first screen shot shows the 1547-2018 selected after selecting 1547-2003.

42 ENGINEERING↗

DOE OSTI2020

Emerging Plug Load Management Technologies that Save Energy and Time

This fact sheet introduces two emerging technologies that could streamline plug load management (PLM) for increased energy savings for building owners: learning behavior algorithms (LBA) and automatic and dynamic load detection (ADLD). Plug loads are responsible for 47% of the energy consumed in commercial buildings, yet their distributed and ever-changing nature makes them challenging to manage. PLM systems exist today that use smart plugs to meter and control devices at the outlet level, but their uptake has been relatively slow in part because of the significant labor required for installation and maintenance. LBA and ADLD may address these challenges and provide additional energy efficiency and nonenergy benefits.

Plug and process loads, PPL, plug loads, plug load↗

DOE OSTI2024

Multi-agent voltage control in distribution systems using GAN-DRL-based approach

Active distribution grids can experience voltage fluctuations and violations due to the high penetration of variable distributed energy resources (DERs). These problems might occur because of the uncertain and variable generation natures of these resources, especially solar photovoltaic resources, during panel shadowing scenarios. Volt-VAR control (VVC) is an efficient method that controls the reactive power set-points of the inverters to regulate the voltage of distribution grids. Although several VVC approaches have been proposed recently, the performance of these approaches degrades significantly if behind-the-meter solar generation data are unobservable/missing. Therefore, it is necessary to impute missing/unobservable PV data accurately to be utilized in VVC approaches. Further, this paper proposes a model-free, data-driven, centrally trained, and decentrally executed multi-agent deep reinforcement learning-based VVC architecture to regulate the voltage of distribution networks. A generative adversarial network (GAN) is incorporated to impute the unobservable PV data accurately, which improves the performance of the proposed control architecture. The proposed multi-agent-soft-actor–critic algorithm (MASAC)-based VVC technique utilizes the actual PV dataset as well as the imputed dataset from the GAN framework to learn the optimal coordinated control policy for controlling the optimal reactive power set-points of PV inverters. The effectiveness of the proposed approach is analyzed on a modified IEEE 34-bus test case with added PV inverters. The results are compared and analyzed with a base case model with no VVC and VVC with a local droop control approach, genetic algorithm optimization, and a centralized soft actor–critic-based approach. Moreover, the performance of the proposed approach is compared with that of a multi-agent VVC framework without using the PV generation data and load information as the system state. The results illustrate that the proposed method with more state input improves the voltage profile and reduces the power loss of the network across various loading and PV generation scenarios.

14 SOLAR ENERGY↗