SEARCH · Engineering Papers
Results for “converter”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Enabling Technology for Energy Sustainability: Power Electronic Converter Control for Renewables
To ensure high penetration of renewable energy sources into power grids, their interfacing inverters need to be designed to provide grid support functions. Important grid support functions include frequency and voltage support. To this end, the research community has recently invested heavily on grid-forming control pilot projects. Grid forming control aims to replace traditional grid following control, which is based on phase-locked loop and can achieve decoupled real and reactive power control. Here, in this article, we review the state-of-the-art grid following and forming technology and point out some deficiencies in dynamic performance in the widely adopted grid-forming control design. We also examine how to ensure that the vector control capable of decoupled real and reactive power regulation can also be achieved in the grid forming design. This type of design has been prototyped and shown great potential to enable retrofitting of large amounts of grid-following controllers through purely software algorithm update. The technology ensures reliable operation of power grids with high penetration of IBRs, thereby further reducing fossil fueled energy sources and cut down carbon emission.
Review of Small-Signal Converter-Driven Stability Issues in Power Systems
Not Available
An RMRAC With Deep Symbolic Optimization for DC–AC Converters Under Less-Inertia Power Grids
Not Available
Control Co-Design of Power Take-Off Systems for Wave Energy Converters Using WecOptTool
Not Available
Efficiency Analysis of the Wave-to-Grid Energy Conversion of the UniWave200 Wave Energy Converter
Not Available
Nonlinear Model Predictive Control Based on Real-Time Iteration Scheme for Wave Energy Converters Using WEC-Sim
One of several challenges that wave energy technologies face is their inability to generate electricity cost-competitively with other grid-scale energy generation sources. Several studies have identified two approaches to lower the levelised cost of electricity: reduce the cost over the device's lifetime or increase its overall electrical energy production. Several advanced control strategies have been developed to address the latter. However, only a few take into account the overall efficiency of the power take-off (PTO) system, and none of them solve the optimisation problem that arises at each sampling time on real-time. In this paper, a detailed Nonlinear model predictive control (NMPC) approach based on the real-time iteration (RTI) scheme is presented, and the controller performance is evaluated using a time-domain hydrodynamics model (WEC-Sim). The proposed control law incorporates the PTO system's efficiency in a control law to maximise the energy extracted. The study also revealed that RTI-NMPC clearly outperforms a simple resistive controller.
1.1 eV GaInAs Cell Development for Dual-Use Solar and 1070 nm Laser Power Converters
Dual-use photovoltaic cells can receive solar and laser power simultaneously to generate current, an application relevant to space and terrestrial industries. This study investigates two concepts of solar cells optimized for dual-use 1070 nm laser and solar power conversion, a single-junction and triple-junction cell. The cell designs are based upon the 3- junction inverted metamorphic solar cell, previously shown highly efficient for solar conversion. Because it is closely bandgap-tuned for a 1070 nm laser, the 1 eV bottom junction is incorporated into each of the two designs, making its development key to the success of both concepts. However, each design requires some modification for efficient dual use. The single-junction device requires optimization to reduce short wavelength absorption of the broad solar spectrum. In both devices, the graded buffer layers in the GaInAs cell affect the cell's performance by reducing threading dislocations in the active junction. However, the buffer in the three-junction device also acts as a lateral transport layer and so affects the fill factor depending on its sheet resistance. By varying the buffer thickness, we demonstrate a direct relationship between buffer thickness and sheet resistance reduction, while considering implications to open-circuit voltages. We also performed resistance modeling to determine the optimal grid spacing and thickness of the grid fingers to minimize losses due to sheet resistance and grid shading. Efficiency data for a one junction GaInAs cell demonstrates a laser conversion efficiency of 38% at 1070 nm wavelength without an anti-reflection coating.
TEAMER - Extreme Events Modeling for the MARMOK-OWC Wave Energy Converter
Through the TEAMER program, Sandia National Laboratories (SNL) collaborated with IDOM Incorporated to study their MARMOK-Oscillating Water Column (MARMOK-OWC) wave energy conversion device. The study yielded a quantitative understanding of hydrodynamic pressures on the oscillating water column (OWC) device surfaces, the mooring tensions, and the dynamic performance of the device under extreme ocean wave conditions. This project utilized a comprehensive multi-phase Navier-Stokes flow solver with an overset body-fit mesh to predict fluid velocities and hydrodynamic forces on the MARMOK-OWC device. Computational Fluid Dynamics (CFD) analysis were conducted using OpenFOAM. This data includes the OpenFOAM cases (setup and data) to run the extreme events developed during the project. This project is part of the TEAMER RFTS 4 (request for technical support) program.
CESIUM THERMIONIC CONVERTERS AND GENERATORS FOR SOLAR SPACE POWER SYSTEMS
Design, fabrication and testing of solar thermionic generators for use as space power systems
Scan converter feasibility study final report
Electrostatic image recorder for conversion of Apollo television images to standard commercial television format
Study of thin film large area photovoltaic solar energy converter Second quarterly report, 25 Feb. - 24 May 1966
Cadmium sulfide thin film solar cell development
Static Longitudinal Stability and Control of a Convertible-type Airplane as Affected by Articulated-and Rigid-propeller Operation
Explore the source record for details and available documents.
Experimental and numerical determination of temperature gradients for a single tube alkali metal thermal-to-electric converter cell
This paper presents the results from the experimental and numerical determination of shell temperature gradients for a single tube AMTEC cell evaluated under simulated deep space operating conditions.
Power converter module and assembly
Explore the source record for details and available documents.
Multi Band Gap High Efficiency Converter (Rainbow)
This papter reprots on the reexamination of the spectrally split, individually matched cell approach using modern-day optics and lightweight structures.