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Vacuum Insulator Flashover of Ultra High Vacuum Compatible Insulators

IEEE International Pulsed Power Conference

Leckbee, Joshua; Simpson, Sean; Ziska, Derek; Bui, Bill

High voltage vacuum systems with stringent vacuum requirements are often designed with ceramic insulators which have low flashover strength. In this paper, we report on experimental results comparing pulsed high voltage flashover of Rexolite®(cross-linked polystyrene), a pulsed power industry standard vacuum insulator, to Kel-F® (polyclorotrifluoroethylene), a plastic with significantly lower vacuum outgassing. Our results show similar surface flashover results with the two materials, with both exhibiting large spread in flashover electric field. The average electric field for flashover of each material agree well with predictions based on previously published results.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Single Diode Parameter Extraction from In-Field Photovoltaic I-V Curves on a Single Board Computer

Conference Record of the IEEE Photovoltaic Specialists Conference

Jones, Christian B.; Hansen, Clifford

In this paper, we present a new, light-weight approach for extracting the five single diode parameters (IL, Io, RS, RSH, and nNsVt) for advanced, in-field monitoring of in situ current and voltage (I-V) tracing devices. The proposed procedure uses individual I-V curves, and does not require the irradiance or module temperature measurement to calculate the parameters. It is suitable for operation on a small, single board computer at the point of I-V curve measurement. This allows for analysis to occur in the field, and eliminates the need to transfer large amounts of data to centralized databases. Observers can receive alerts directly from the in-field devices based on the extraction, and analysis of the commonly used single diode equivalent model parameters. This paper defines the approach and evaluates its accuracy by subjecting it to I-V curves with known parameters. Its performance is defined using actual I-V curves generated from an in situ scanning devices installed within an actual photovoltaic production field. The algorithm is able to operate at a high accuracy for multiple module types and performed well on actual curves extracted in the field.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Electro-Optical Measurement of Electric Fields for Pulsed Power Systems

IEEE International Pulsed Power Conference

Owens, Israel J.; Grabowski, Theodore C.; Joseph, N.; Coffey, Sean; Ulmen, Ben; Kirschner, Debra; Rainwater, K.; Struve, Kenneth

The electric field strength between the cathode and anode (i.e., the voltage) of a pulsed power machine is one of the most important operating parameters of the device. However, to date, accurate and precise voltage measurements on these high energy pulsed power systems have proved difficult if not virtually impossible to perform. In many cases, the measurements to be performed take place in an environment cluttered with electromagnetic interference (EMI), radio frequency interference (RFI), and electron pollution, and there is the potential for electrical discharge (or arcing), there is limited physical access, or the measurement area is deemed unsuitable due to radiation safety concerns. We report on an electro-optical-based approach to measuring strong, narrow-pulse-width electric fields that requires no interfering metallic probes or components to disturb the field to be measured. Here we focus on device theory, operating parameters and a laboratory experiment.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Geographic Assessment of Photovoltaic Module Environmental Degradation Stressors

Conference Record of the IEEE Photovoltaic Specialists Conference

Jones, Christian B.; Karin, Todd; Jain, Anubhav; Hobbs, William B.; Libby, Cara

Environmental stress can degrade photovoltiac (PV) modules. We perform a literature search to identify models that estimate the damage caused by exposure to various environmental stressors, including temperature, radiation, and humidity. The weather-related variables, including ambient temperature, irradiance and humidity are calculated using the Global Land Data Assimilation System (GLDAS). The analysis also calculated degradation-model stressors, module temperature, plane of array irradiance, and relative humidity and compared these PV-specific variables to identify correlations and the translation required to represent the stressor accurately. The results show that global horizontal (GHI) irradiance can be used instead of plane-of-array irradiance to represent radiation dose. However, module temperature can be significantly different from ambient temperatures and specific humidity is significantly different from relative humidity.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Grid-forming Inverter Experimental Testing of Fault Current Contributions

Conference Record of the IEEE Photovoltaic Specialists Conference

Gurule, Nicholas S.; Hernandez-Alvidrez, Javier; Reno, Matthew J.; Summers, Adam K.; Gonzalez, Sigifredo; Flicker, Jack D.

Historically, photovoltaic inverters have been grid-following controlled, but with increasing penetrations of inverter-based generation on the grid, grid-forming inverters (GFMI) are gaining interest. GFMIs can also be used in microgrids that require the ability to interact and operate with the grid (grid-tied), or to operate autonomously (islanded) while supplying their corresponding loads. This approach can substantially improve the response of the grid to severe contingencies such as hurricanes, or to high load demands. During islanded conditions, GFMIs play an important role on dictating the system's voltage and frequency the same way as synchronous generators do in large interconnected systems. For this reason, it is important to understand the behavior of such grid-forming inverters under fault scenarios. This paper focuses on testing different commercially available grid-forming inverters under fault conditions.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Large Acoustoelectric Effect in Wafer Bonded Indium Gallium Arsenide / Lithium Niobate Heterostructure Augmented by Novel Gate Control

2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems and Eurosensors XXXIII, TRANSDUCERS 2019 and EUROSENSORS XXXIII

Siddiqui, Aleem; Hackett, Lisa; Dominguez, Daniel; Tauke-Pedretti, Anna; Friedmann, Thomas A.; Peake, Gregory M.; Miller, Michael; Douglas, James K.; Eichenfield, Matt

This paper demonstrates a monolithic surface acoustic wave amplifier fabricated by state-of-the-art heterogenous integration of a IH-V InGaAs-based epitaxial material stack and LiNb03. Due to the superior properties of the materials employed, we observe electron gain and also non-reciprocal gain in excess of 30dB with reduced power consumption. Additionally, we present a framework for performance optimization as a function of material parameters for a targeted gain. This platform enables further advances in active and non-reciprocal piezoelectric acoustic devices.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

EXPERIMENTAL RESULTS FROM THE 1.2 MA 2.2 m DIAMETER LINEAR TRANSFORMER DRIVER AT SANDIA NATIONAL LABS

Douglass, Jonathan; Hutsel, Brian T.; Leckbee, Joshua J.; Stoltzfus, Brian S.; Wisher, Matthew L.; Savage, Mark E.; Stygar, William A.; Breden, Eric W.; Calhoun, Jacob D.; Cuneo, Michael E.; Jaramillo, Deanna M.; Johns, Owen; Jones, Michael; Lucero, Diego; Moore, James M.; Sceiford, M.E.; Kiefer, Mark L.; Mulville, Thomas D.; Sullivan, Michael A.; Hohlfelder, Robert J.

Abstract not provided.

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TYPE Conference Poster YEAR 2019
DOIOSTI

Simulation of Grid-Forming Inverters Dynamic Models using a Power Hardware-in-the-Loop Testbed

Conference Record of the IEEE Photovoltaic Specialists Conference

Hernandez-Alvidrez, Javier; Summers, Adam K.; Reno, Matthew J.; Flicker, Jack D.; Pragallapati, Nataraj

Modern power grids include a variety of renewable Distributed Energy Resources (DERs) as a strategy to comply with new environmental and renewable portfolio standards (RPSs) imposed by state and federal agencies. Typically, DERs include the use of power electronic (PE) interfaces to interactwith the power grid. Recently this interaction has not only been focused on supplying maximum available energy, but also on supporting the power grid under abnormal conditions such as low voltage/frequency conditions or non-unity power factor. Over the last few years, grid-following inverters (GFLIs) have proven their value while providing these ancillary grid-support services either at residential or utility scale. However, the use of grid-forming inverters (GFMIs) is gaining momentum as the penetration-level of DERs increases and system inertia decreases. Under abnormal operating conditions, GFMIs tend to better preserve grid stability due to their intrinsic ability to balance loadswithout the aid of coordination controls. In order to gain and propose fundamental insights into the interfacing of GFMIs to real time simulation, this paper analyzes the dynamics of two different GFMI simulation models in terms of stability and load changes using a Power Hardware-in-the-Loop (PHIL) simulation testbed.

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TYPE Conference Poster YEAR 2019
OSTIScopus

Grid-forming Inverter Experimental Testing of Fault Current Contributions

Conference Record of the IEEE Photovoltaic Specialists Conference

Gurule, Nicholas S.; Hernandez-Alvidrez, Javier; Reno, Matthew J.; Summers, Adam K.; Gonzalez, Sigifredo; Flicker, Jack D.

Historically, photovoltaic inverters have been grid-following controlled, but with increasing penetrations of inverter-based generation on the grid, grid-forming inverters (GFMI) are gaining interest. GFMIs can also be used in microgrids that require the ability to interact and operate with the grid (grid-tied), or to operate autonomously (islanded) while supplying their corresponding loads. This approach can substantially improve the response of the grid to severe contingencies such as hurricanes, or to high load demands. During islanded conditions, GFMIs play an important role on dictating the system's voltage and frequency the same way as synchronous generators do in large interconnected systems. For this reason, it is important to understand the behavior of such grid-forming inverters under fault scenarios. This paper focuses on testing different commercially available grid-forming inverters under fault conditions.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Fault Current Correction Strategies for Effective Fault Location in Inverter-Based Systems

Conference Record of the IEEE Photovoltaic Specialists Conference

Matthews, Ronald C.; Hossain-Mckenzie, Shamina; Reno, Matthew J.

The grid of the future will integrate various distributed energy resources (DERs), microgrids, and other new technologies that will revolutionize our energy delivery systems. These technologies, as well as proposed grid-support functions, require inverter-based systems to achieve incorporation into the overall system(s). However, the presence of inverters and other power electronics changes the behavior of the grid and renders many traditional tools and algorithms less effective. An inverter is typically designed to limit its own current output to avoid overloading. This can result in both voltage collapse at the inverter output and limited energy being delivered during a fault so that protective relays cannot respond properly. To avoid sustained faults and unnecessary loss of service, it is proposed that either supercapacitor or flywheel energy storage be utilized to energize faults upon overload of the inverter to achieve fault current correction. This paper will discuss these challenges for inverter-based system fault detection, explore fault current correction strategies, and provide MATLAB/Simulink simulation results comparing the effectiveness of each strategy.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Cygnus System Timing

IEEE International Pulsed Power Conference

Ormond, Eugene C.; Garcia, Michael R.; Parrales, Martin F.; Smith, John R.; Amos, Percy H.; Hogge, Keith W.; Misch, Michael K.; Mohammed, Mohammed; Truong, Hoai T.V.

The Cygnus Dual Beam Radiographic Facility consists of two identical radiographic sources each with a dose rating of 4-rad at 1 m, and a 1-mm diameter spot size. The development of the rod pinch diode was responsible for the ability to meet these criteria1. The rod pinch diode in a Cygnus machine uses a 0.75-mm diameter, tapered tip, tungsten anode rod extended through a 9-mm diameter, aluminum cathode aperture. When properly configured, the electron beam born off the aperture edge can self-insulate and pinch onto the tip of the rod creating an intense, small x-ray source. The Cygnus sources are utilized as the primary diagnostic on Subcritical Experiments that are single-shot, high-value events. The system timing on Cygnus will be evaluated as related to the following system elements: HV trigger generator, Marx, pulse forming line and rod pinch diode. Spare trigger generators will also be included in this evaluation.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Three-Dimensional Model of the Saturn Accelerator Water Tri-Plate Transmission Line Connection to the Vacuum Insulator Stack

IEEE International Pulsed Power Conference

Struve, Kenneth; Ulmen, Ben

Calculation of the power flow from the 36 pulse forming lines to the vacuum region of Saturn has always been complicated by the three-dimensional structure of the rod and bottle connections to the vacuum insulator stack. Recently we have completed a 3-D calculation of the bottle configuration and found a large error in previous impedance estimates. We have used this calculation to determine impedance and to construct a 2-D model of each of the 36 bottles of each level of the insulator using the Transmission Line Matrix (TLM) technique. These TLM models are then used in a 2-D model for each of the three levels of the insulator. Each model starts at a measured forward-going pulse in the water tri-plate and ends at the Brehmstrahlung load at the center of the machine. Because of long transmission line lengths and short pulse lengths, each level can be considered independent of the others. A combination of the three models then represents a quasi-3-D model of the load region of the machine. The results of these calculations agree well with measurement and thereby provide confidence in simulation predictions for those areas where measurements are not possible. Details of the 3-D bottle calculation, the TLM model, and results of the load region simulations using this model are given.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Determining interface structures in vertically aligned nanocomposite films

APL Materials

Lu, Ping

Vertically aligned nanocomposite (VAN) films have self-assembled pillar-matrix nanostructures. Owing to their large area-to-volume ratios, interfaces in VAN films are expected to play key roles in inducing functional properties, but our understanding is hindered by limited knowledge about their structures. Motivated by the lack of definitive explanation for the experimentally found enhanced ionic conductivity in Sm-doped-CeO2/SrTiO3 VAN films, we determine the structure at vertical interfaces using random structure searching and explore how it can affect ionic conduction. Interatomic potentials are used to perform the initial searching, followed by first-principles calculations for refinement. Previously unknown structures are found, with lower energy than that of an optimized hand-built model. We find a strongly distorted oxygen sublattice which gives a complex landscape of vacancy energies. The cation lattice remains similar to the bulk phase, but has a localized strain field. The excess energy of the interface is similar to that of high angle grain boundaries in SrTiO3.

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TYPE Journal Article YEAR 2019
DOIOSTIScopus
Results 24801–25000 of 101,000
Results 24801–25000 of 101,000
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