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At least 847 records · Page 47

All sources NASA NTRS DOE OSTI

DOE OSTI2019

Estimating Customer Impact of Volt-Watt Using Only Smart Meter Voltage Data

The autonomous inverter control mode known as volt-watt control can be useful as a backstop against high customer voltages outside of the ranges specified in ANSI C84.1 (i.e. above 1.05-1.06 per unit). Volt-watt control mitigates high voltages by directly reducing the active power output of a distributed energy resource based on local voltage measurements. Therefore volt-watt control also can impact the energy produced by the DER (e.g. PV system), especially for customers with persistently high voltages, and in such cases it is difficult to determine exactly how much the DER has been curtailed because it is not generally known exactly how much energy the PV system could have produced. These slides propose a relatively simple method of estimating the DER's energy curtailment using only data from the utility advanced metering infrastructure (AMI) data). The method proves surprisingly accurate when validated against detailed quasi-static time-series simulations and against limited field data.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2019

High voltage transformer

A high-voltage transformer is disclosed. The high-voltage transformer includes a transformer core; at least one primary winding wound once or less than once around the transformer core; a secondary winding wound around the transformer core a plurality of times; an input electrically coupled with the primary windings; and an output electrically coupled with the secondary windings that provides a voltage greater than 1,1200 volts. In some embodiments, the high-voltage transformer has a stray inductance of less than 30 nH as measured on the primary side and the transformer has a stray capacitance of less than 100 pF as measured on the secondary side.

42 ENGINEERING↗

DOE OSTI2019

Subcritical-voltage magnetron RF power source

A system and method of operating a magnetron power source can achieve a broad range of output power control by operating a magnetron with its cathode voltage lower than that needed for free running oscillations (e.g., below the Kapitsa critical voltage or equivalently below the Hartree voltage) A sufficiently strong injection-locking signal enables the output power to be coherently generated and to be controlled over a broad power range by small changes in the cathode voltage. In one embodiment, the present system and method is used for a practical, single, frequency-locked 2-magnetron system design.

Kazakevich, Grigory M.↗

DOE OSTI2019

Submodule Capacitor Reduction for a 1 MVA SiC-Based Modular Multilevel Converter Motor Drive using High Frequency Common-Mode Voltage Injection

This paper describes a strategy to reduce the size of submodule capacitors of a 1 MVA, 0-1 kHz, 7-level modular multilevel converter (MMC) based medium voltage variable speed drive (MVVSD) using 1.7 kV SiC MOSFETs. Hardware designs of submodules to withstand high dv/dt and capacitor selection based on common mode voltage injection have been presented in literature. The issue with injection is the error in tracking of injected circulation current which results in fundamental frequency fluctuations in the submodule capacitor voltage. This paper presents a strategy for higher frequency sinusoidal common mode voltage based on more accurate tracking of the circulating current; realized through an improved control strategy combined with a higher switching frequency. Using the methods presented in this paper, a smaller submodule capacitance and reduced output current THD of the motor drive is achieved. A loss analysis model is proposed to evaluate the effect of the proposed strategy on the MMC efficiency. This helps balance the reduction in the capacitor against the increase in the losses as a result of increased switching frequency. Simulations and a down-scaled experimental setup are used to demonstrate this concept.

Potty, Karun↗

DOE OSTI2020

High voltage, cross-field, gas switch and method of operation

A high voltage gas switch includes a gas-tight housing containing an ionizable gas at a preselected gas pressure. The gas switch includes a gas-tight housing containing an ionizable gas at a gas pressure selected based upon a Paschen curve for the ionizable gas, where the Paschen curve plots breakdown voltages of the ionizable gas as a function of gas pressure multiplied by grid-to-anode distance, and where values of gas pressure multiplied by grid-to-anode distance increase over at least a portion of the Paschen curve in conjunction with increasing breakdown voltages. The gas switch also includes an anode disposed within the gas-tight housing, a cathode disposed within the gas-tight housing, and a control grid positioned between the anode and the cathode, where the control grid is spaced apart from the anode by a grid-to-anode distance selected based upon a desired operating voltage.

42 ENGINEERING↗

DOE OSTI2020

Subcritical-voltage magnetron RF power source

30 DIRECT ENERGY CONVERSION↗

DOE OSTI2020

Decentralized Voltage optimization Method for Distribution Networks with Distributed PVs

In order to solve the voltage violations caused by high penetration distributed photovoltaics (PVs), this paper proposes a decentralized voltage optimization method for distribution networks. Through the optimal dispatch of distributed PVs and reactive power resources, it realizes the voltage security and economic operation of distribution systems and facilitates the integration of massive distributed PVs. The proposed method is inspired by the idea of locational marginal price (LMP) and feasible cutting plane. It separates the optimization of boundary bus voltage and power flow in adjacent regions and uses the interaction of boundary variables’ marginal prices to obtain the optimal solution. The effectiveness and accuracy of the proposed method are demonstrated via simulation test on a practical l0kV feeder in China.

Xue, Yaosuo↗

DOE OSTI2021

Synthetic, Realistic Transmission and Distribution Co-Simulation for Voltage Control Benchmarking

As distributed energy resources (DERs) play an increasing role in generation and grid services, control and market paradigms will need to be tested with models that incorporate transmission and distribution systems. The test systems will need to be realistic and accessible for researchers to form conclusions about realistic behaviors and maintain comparability and repeatability of results. These test systems also must have high resolution models of sufficient size for realistic distribution and transmission interaction. This paper demonstrates the tightly coupled HELICS-based co-simulation of realistic synthetic distribution and transmission models for the Austin metropolitan area and how this framework can be used to analyze resultant behaviors from distributed resources and their controls. These results are compared to the same distribution system run without co-simulation using a fixed feed-in voltage. Results show that even without advanced voltage controls, the feed-in voltage response when coupled to the transmission system results a lower level of voltage excursions, suggesting the importance of using this type of realistic, tightly coupled, transmission and distribution co-simulation when assessing DERs.

27 ARPA - Advanced Research Projects Agency-Energy↗

DOE OSTI2021

High-voltage insulator having multiple materials

High-voltage insulators are disclosed that are capable of handling diverse requirements, such as providing high standoff voltages, high temperature cycling, and the ability to withstand flexural stress. One high-voltage insulator includes a first piece formed from a first material, a second piece formed from a second material, and an interface section where the first piece contacts with and forms a seal with the second piece. The interface includes a first groove located that accommodates a first gasket, sets of matching threads on the first and second pieces. The interface section further accommodates a second gasket. In this multi-piece high-voltage insulator, the first material can have a first set of flexural, heat resistance, and electrical standoff characteristics suitable for a first environment, and the second material can have a second set of flexural, heat resistance and electrical standoff characteristics suitable for a second environment.

Podpaly, Yuri Anatoly↗

DOE OSTI2022

Hierarchical distributed voltage regulation

Embodiments of the disclosure provide for hierarchically distributed voltage regulation and power flow optimization in a power distribution network. According to one embodiment, a regional coordinator system may determine power flow for an autonomous grid (AG) representing a portion of the distribution network based on a set of voltage parameters from nodes in the AG. The set of voltage parameters my include a current voltage magnitude. The regional coordinator system may provide, to a central controller system of the distribution network, one or more power flow parameters based on the determined power flow for the AG.

Zhou, Xinyang↗

DOE OSTI2023

A Smart Silicon Carbide Power Module With Pulse Width Modulation Over Wi-Fi and Wireless Power Transfer-Enabled Gate Driver, Featuring Onboard State of Health Estimator and High-Voltage Scaling Capabilities: Preprint

A wide range of utility applications require controllable switches with features such as high-voltage (HV) blocking and high-current carrying capacity especially at high pulse width modulation (PWM) frequency. Low and medium voltage utility applications such as motor drives and flexible AC transmission systems (FACTS) as well as solid state transformers (SST) could also benefit from a low-cost HV switching module. Wide band gap (WBG) semiconductors such as SiC and GaN MOSFETs are considered to be the present and next generation device choices, although they have their own limitations. For relatively HV applications with demanding thermal management, SiC is still the only choice, and GaN dominates the low voltage regime. This manuscript proposes a new half bridge power MOSFET module that is suitable for conventional H-bridge of multilevel configurations used in HV applications. Constructed from bare SiC dies, this half bridge module takes advantage of (1) optimized MOSFET placement inside the module, (2) customized heat exchanger, manifold and cooling, (3) integrated gate driver module with PWM over wi-fi to eliminate the need for low voltage signals, (4) wireless power transfer (WPT) enabled gate driver and other ancillary circuits, (5) and the option to incorporate an onboard state of health (SOH) estimator module onboard. The entire architecture has been designed and built at National Renewable Energy Laboratory (NREL), Golden, CO.

baseplate design↗

DOE OSTI2022

Masked fault detection for reliable low voltage cache operation

Systems, apparatuses, and methods for implementing masked fault detection for reliable low voltage cache operation are disclosed. A processor includes a cache that can operate at a relatively low voltage level to conserve power. However, at low voltage levels, the cache is more likely to suffer from bit errors. To mitigate the bit errors occurring in cache lines at low voltage levels, the cache employs a strategy to uncover masked faults during runtime accesses to data by actual software applications. For example, on the first read of a given cache line, the data of the given cache line is inverted and written back to the same data array entry. Also, the error correction bits are regenerated for the inverted data. On a second read of the given cache line, if the fault population of the given cache line changes, then the given cache line's error protection level is updated.

Ganapathy, Shrikanth↗

DOE OSTI2023

High-voltage insulators having multiple materials

Podpaly, Yuri Anatoly↗

DOE OSTI2025

Field Testing of PID-p Susceptible Bifacial PERC Modules: Impact of Light, Voltage and Module History

This work investigates the potential induced degradation-polarization (PID-p) of bifacial passivated emitter and rear contact (PERC) modules installed in the field at the Florida Solar Energy Center. 22 modules were stressed over 1 year under various voltage (-1500V, -3500, +1500V) and mounting configurations (close to ground, 2 meters from ground, close to roof). The positively stressed modules were anticipated to have experiences PID-p on their front side. However, no degradation was observed, as the light-induced recovery effect effectively counteracted the degradation. The negatively stressed modules experienced Pmax drops during 2 weeks before stabilizing at 5-6% loss. I-V and EL characteristics suggest a PID-p degradation on the rear side. Lower degradation rates are observed with lower voltage and when the mounting configuration allows more albedo light on the rear side to compensate for the degradation. PID-p is observed to stabilize at similar level for the voltage and mounting configuration tested with slightly lower Pmax in winter. EL imaging reveals that cells are not degrading at the same rate across a module. Some cells get darker and then brighter which corresponds to the silicon/passivation interface going through depletion and then inversion when enough positive charges are accumulated. After full light-recovery, the modules were tested again along with 22 brand-new ones to assess the impact of the module history. Results confirmed the trends observed in the first year with PID-p occurring at voltage as low as -600V and recovered modules degrading faster than brand-new ones.

14 SOLAR ENERGY↗

DOE OSTI2025

Optimizing Insulation Design for Transformers in Medium Voltage Power Conversion Systems

Medium-frequency transformers (MFTs) play a crucial role in medium-voltage (MV) solidstate transformer (SST) systems, particularly in extreme fast charging applications. Achieving partial discharge (PD)-free operation while maintaining high power density is a significant challenge due to the high electric field (E-field) stresses inherent in MV applications. This dissertation focuses on the insulation design and optimization of MFTs used in both the main power electronics circuits and auxiliary power supplies. The study begins with an overview of insulation testing methodologies, including high potential tests, basic insulation level tests, and PD tests, which are critical for evaluating MFT insulation reliability. Given the importance of PD-free operation for long-term reliability, particular emphasis is placed on understanding PD mechanisms, including void, corona, and surface discharge, and their mitigation strategies. A high voltage isolated auxiliary power supply is then introduced, utilizing a gapped transformer encapsulated in silicone gel. This design achieves PD-free insulation up to 18 kV RMS while maintaining low coupling capacitance to minimize common-mode current. The proposed solution ensures reliable operation in MV environments and offers a scalable approach for auxiliary power in cascaded SST architectures. To improve MFT insulation in main power conversion circuits, a novel structure is developed using polypropylene sheets and potting compounds to create a void-free air gap, effectively mitigating E-field intensity. A prototype transformer with this insulation structure is built and achieves PD-free operation up to 30 kV RMS. This design is experimentally validated in a resonant converter operating at 46 kW, demonstrating its feasibility for MV SST applications. Further optimization is implemented to enhance MFT performance for dual-active-bridge(DAB) converters by integrating a semiconductive shielding layer within the insulation structure. This shielding layer improves the magnetic coupling coefficient while effectively confining the E-field within high insulation materials, thereby reducing eddy current losses. The optimized MFT achieves PD-free operation at 12.6 kV RMS and is successfully tested in a DAB converter operating at 43 kW, which meets the insulation requirements for a 13.2 kV SST system. This dissertation advances MFT insulation design by introducing and experimentally validating novel approaches that improve high voltage insulation while optimizing magnetic coupling and manufacturability. The proposed insulation structures enable PD-free operation while minimizing insulation material usage and simplifying assembly, making them ideal for high power, high voltage applications.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2026

Submodule-Level Decentralized Control for Cascaded Quadruple Active Bridge-Based Medium-Voltage Converters: Preprint

High-power, low-voltage DC (LVDC) loads, such as AI data centers, electric vehicle fast-charging hubs, and hydrogen electrolyzers, are accelerating the deployment of solid-state transformers (SSTs) that directly interface medium-voltage AC (MVAC) to LVDC, streamlining power delivery. This paper proposes a submodule-level decentralized control strategy for an SST comprising a cascaded H-bridge (CHB) active rectifier on the MVAC side and per-module quadruple-active-bridge (QAB) converters on the LVDC side with local controllers. The proposed strategy eliminates the need for high-fidelity, real-time cross-isolation communication by synchronizing all active bridges to a common heartbeat signal and enabling the primary- and secondary-side controllers to generate independent local control signals (phase shifts). The resultant phase shifts naturally govern average and double-line frequency power transfer between active bridges, enabling each side to meet its control objectives using only local measurements. Detailed controller design considerations are presented based on a stability analysis. Comprehensive electromagnetic-transient simulations demonstrate tight DC-link voltage regulation, high-quality grid currents, and robust operation under load transients and grid disturbances, without real-time communication among the submodule controllers. These results indicate that the proposed scheme can significantly enhance the reliability, scalability, and flexibility of cascaded bridge-based medium-voltage converters.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2021

Superior long-term cycling of high-voltage lithium-ion batteries enabled by single-solvent electrolyte

A new single-solvent electrolyte system comprising lithium bis(fluorosuflonyl) imide (LiFSI) and beta-fluorinated sulfone (TFPMS) was designed to enable very stable long-term cycling of high-voltage lithium-ion batteries. Compared to other fluorinated solvents such as alpha-fluorinated sulfone (FMES) and fluorinated carbonate (FEMC), which are prone to reduction on the graphite anode, the LiFSI-TFPMS system displayed outstanding compatibility with graphite. While regular carbonate and sulfone from the LiFSI electrolyte system are compatible with the graphite anode, their high solvating power not only induces severe corrosion on the aluminum cathode current collector at high voltage, but also renders a low aggregation level at a normal salt concentration (about 1.0 M), resulting in the formation of an unstable solid-electrolyte interphase (SEI) on the graphite anode. Owing to the low solvating power of TFPMS, the aggregation level of the LiFSI-TFPMS system is relatively high even at normal salt concentration, which not only facilitates the formation of a robust SEI by the sacrificial decomposition of LiFSI, but also suppresses the aluminum corrosion of the LiFSI electrolyte system at high voltage. Together with the high intrinsic anodic stability of TFPMS, the superior cycling performance of graphite parallel to LiNi 0.6 Co 0.2 Mn 0.2 O 2 cells was achieved by employing the non-flammable LiFSI-TFPMS single-solvent electrolyte system.

25 ENERGY STORAGE↗

DOE OSTI2019

Machine Learning the Voltage of Electrode Materials in Metal-Ion Batteries

Machine-learning (ML) techniques have rapidly found applications in many domains of materials chemistry and physics where large data sets are available. Aiming to accelerate the discovery of materials for battery applications, in this work, we develop a tool based on ML models to predict voltages of electrode materials for metal-ion batteries. To this end, we use deep neural network, support vector machine, and kernel ridge regression as ML algorithms in combination with data taken from the Materials Project database, as well as feature vectors from properties of chemical compounds and elemental properties of their constituents. We show that our ML models have predictive capabilities for different reference test sets and, as an example, we utilize them to generate a voltage profile diagram and compare it to density functional theory calculations. In addition, using our models, we propose nearly 5000 candidate electrode materials for Na- and K-ion batteries. We also make available a web-accessible tool that, within a minute, can be used to estimate the voltage of any bulk electrode material for a number of metal ions. Here, these results show that ML is a promising alternative for computationally demanding calculations as a first screening tool of novel materials for battery applications.

25 ENERGY STORAGE↗