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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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Incommensurate two-dimensional checkerboard charge density wave in the low-dimensional superconductor Ta 4 Pd 3 Te 16
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Evaluation of an Autonomous Control Scheme for Interconnected DC Microgrids Using a Power Hardware-in-the-Loop Platform
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Co-Optimization of Boost Converter Reliability and Volumetric Power Density Using Genetic Algorithm.
Abstract not provided.
Study of Avalanche Behavior in 3 kV GaN Vertical P-N Diode under UIS Stress for Edge-Termination Optimization.
Abstract not provided.
Testing Machine Learned Fault Detection and Classification on a DC Microgrid.
Abstract not provided.
Accelerated testing of module-level power electronics for long-term reliability
This work has applied a suite of long-term-reliability accelerated tests to a variety of module-level power electronics (MLPE) devices (such as microinverters and optimizers) from five different manufacturers. This dataset is one of the first (only the paper by Parker et al. entitled “Dominant factors affecting reliability of alternating current photovoltaic modules,” in Proc. 42nd IEEE Photovoltaic Spec. Conf., 2015, is reported for reliability testing in the literature), as well as the largest, experimental sets in public literature, both in the sample size (five manufacturers including both dc/dc and dc/ac units and 20 units for each test) and the number of experiments (six different experimental test conditions) for MLPE devices. The accelerated stress tests (thermal cycling test per IEC 61215 profile, damp heat test per IEC 61215 profile, and static temperature tests at 100 and 125 °C) were performed under powered and unpowered conditions. The first independent long-term experimental data regarding damp heat and grid transient testing, as well as the longest term (>9 month) testing of MLPE units reported in the literature for thermal cycling and high-temperature operating life, are included in these experiments. Additionally, this work is the first to show in situ power measurements, as well as periodic efficiency measurements over a series of experimental tests, demonstrating whether certain tests result in long-term degradation or immediate catastrophic failures. Lastly, the result of this testing highlights the performance of MLPE units under the application of several accelerated environmental stressors.
Interconnection Standard Grid-Support Function Evaluations Using an Automated Hardware-in-the-Loop Testbed
Grid operators are increasingly turning to advanced grid-support functions in distributed energy resources (DER) to assist with distribution circuit voltage regulation, bulk system frequency control, and power system protection. The U.S. DER certification standard, Underwriters Laboratories (UL) 1741, was revised in September 2016 to add test procedures for multiple grid-support functions. Sandia National Laboratories, SunSpec Alliance, and growing community of collaborators have undertaken a multiyear effort to create an open-source system validation platform (SVP) that automates DER interconnection and interoperability test procedures by communicating with grid simulators, photovoltaic (PV) simulators, data acquisition systems, and interoperable equipment under test. However, the power hardware required for generating the test conditions may be untenable for many organizations. In this paper, we discuss development of the SVP testing capabilities for UL 1741 tests utilizing a controller hardware-in-the-loop testbed that precludes the need for power hardware using a 34.5 kW Austrian Institute of Technology smart grid controller. Finally, analysis of normal ramp rate, soft start ramp rate, specified power factor, volt-VAr, and frequency-watt advanced grid functions, and the effectiveness of the UL 1741 test protocols are included.
Pathways to the Next-Generation Power System With Inverter-Based Resources: Challenges and recommendations
Managing the stability of today's electric power systems is based on decades of experience with the physical properties and control responses of large synchronous generators. Today's electric power systems are rapidly transitioning toward having an increasing proportion of generation from nontraditional sources, such as wind and solar (among others), as well as energy storage devices, such as batteries. In addition to the variable nature of many renewable generation sources (because of the weather-driven nature of their fuel supply), these newer sources vary in size - from residential-scale rooftop systems to utility-scale power plants - and they are interconnected throughout the electric grid, both from within the distribution system and directly to the high-voltage transmission system. Most important for our purposes, many of these new resources are connected to the power system through power electronic inverters. Collectively, we refer to these sources as inverter-based resources.
A Global Real-Time Superlab: Enabling High Penetration of Power Electronics in the Electric Grid
The Global Real-Time Superlaboratory (Global RT Superlab) represents a vendor-neutral distributed platform based on the virtual interconnection of digital real-time simulators (DRTSs) and hardware-in-the-loop (HIL) setups hosted at eight geographically distributed laboratories in the United States and Europe (Figure 1). This article describes the efforts toward the realization of this largescale virtual infrastructure and explains a demonstration of the multilab setup for simulation and testing of next-generation global power grids.
Performance Specifications for Grid-Forming Technologies
Standards and specifications for inverter-based resources (IBRs) focus primarily on grid-following (GFL) technologies at present. Therefore, these may generally not be appropriate for application in power systems to ensure acceptable operation with grid-forming (GFM) technologies. In some cases, the direct application of prevailing standards and specifications may not be appropriate for - or may even inadvertently limit the potential of - GFM resources. The Universal Interoperability for Grid- Forming Inverters (UNIFI) Consortium is a U.S. Department of Energy funded effort to advance GFM technology. The UNIFI team brings together academic, industrial, and national-lab researchers as well as industry stakeholders (utilities, system operators, vendors) to collaboratively pursue advances in a broad range of GFM technologies. This paper introduces a set of system- and unit-level specifications driven by consensus across the UNIFI project team. These are intended to seamlessly integrate GFM technologies at any scale into power-systems operation and control in a vendor-agnostic manner. A suite of illustrative simulation results that demonstrate the application of and adherence to the proposed specifications are included.
Performance and Reliability of PV Inverter Component and Systems due to Advanced Inverter Functionality.
Abstract not provided.
Updated evaluation of shock hazards to firefighters working in proximity of PV systems
Abstract not provided.
Hazard Analysis of Firefighter Interactions with Photovoltaic Arrays.
Abstract not provided.
Autonomous Control Strategies for Interconnected DC Microgrid Applications with Multiple DER Resource Penetration.
Abstract not provided.
State-of-the-Art Medium- and High-Voltage Silicon Carbide Power Modules, Challenges and Mitigation Techniques: A Review
Silicon carbide (SiC) power modules have been demonstrated potential for improving power density and efficiency for low-voltage power electronics systems. This has resulted in a paradigm shift toward development of medium-voltage and high-voltage (MV/HV) SiC power modules to revolutionize the future power grid and transportation systems. However, designing MV/HV SiC power modules involves significant design challenges due to higher blocking voltage and exacerbation of side effects due to high switching dv/dt and di/dt of SiC devices-concerns that may not be as critical as in low-voltage module development. This article reviews the development of state-of-the-art MV/HV SiC power modules, ranging from 3.3 kV to 40 kV, from both industry and academia. First, a discussion on SiC modules based on voltage level is presented. This is followed by a discussion of challenges associated with designing and testing MV/HV modules- including parasitic controls, electromagnetic interference (EMI), partial discharge, and thermal management-and the corresponding mitigation approaches from various perspectives. We conclude with a summary of major findings and future directions for the development of MV/HV modules.