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At least 181 records · Page 10

Photovoltaic power conditioning subsystem: State of the art and development opportunities

Photovoltaic systems, the state of the art of power conditioning subsystem components, and the design and operational interaction between photovoltaic systems and host utilities are detailed in this document. Major technical issues relating to the design and development of power conditioning systems for photovoltaic application are considered; these include: (1) standards, guidelines, and specifications; (2) cost effective hardware design; (3) impact of advanced components on power conditioning development; (4) protection and safety; (5) quality of power; (6) system efficiency; and (7) system integration with the host utility. Theories of harmonic distortion and reactive power flow are discussed, and information about power conditioner hardware and manufacturers is provided.

Krauthamer, S.↗

Hydrodynamic Qualities of a 1/10-Size Powered Dynamic Model of the XP5Y-1 Flying Boat in Smooth Water: Langley Tank Model 246, TED No. NACA DE 320

The hydrodynamic characteristics of a 1/10-size powered dynamic model of the XP5Y-1 flying boat were determined in Langley tank no. 1. Stable take-offs were possible at all practicable positions of the center of gravity and flap deflections. An increase in gross load from 123.5 to 150.0 pounds (21.5 percent) had only a slight effect on the stable range for take-off. A decrease in forward acceleration from 3.0 to 1.0 feet per second per second had only a very small effect on the stable range for take-off. In general, the landings were free from skipping except at trims below 6 deg where one skip was encountered at an aft position of the center of gravity. The model porpoised during the landing runout at all positions of the center of gravity when landed at trims above 10 deg. Spray in the propellers was light at the design gross load, and was not considered excessive,at a gross load of 136.0 pounds.

Woodward, David R.↗

The Core Flight System (cFS): NASA Quality Flight Software to Power Science and Exploration Available to the World

The presentation is planned to be a continuation of two previous discussions completed at the FSW Workshop regarding the cFS Test Framework (CTF) and Engineering Data Sheets (EDS). The presentation will also cover the latest advancements in cFS, including: 1. Quick into to cFS 2. An overview of our software release process + Git repo 3. Release of EDS files for the cFE + open-source apps 4. Overview of how to independently verify EDS files using CTF + what they can be used for. 5. Future plans for cFS. This presentation complements the talk on configuration management of distributed cFS repos, to be presented by Tam Ngo from Johnson Space Center.

Dan Knutsen↗

Ultra Long-Lived, Self-Surveying Autonomous Air Quality Sensing - Executive Summary

We set out to evolve ultra-low power air quality sensing technologies developed at JSC to add a highly accurate positioning sensor based on SBIR technology to give a self-surveying air quality monitoring platform with years-long lifetime on a small, disposable coin cell battery. Using Radio Frequency Identification (RFID) technology for data transport, the system can take advantage of RFID-based inventory management systems in place on lunar exploration assets to provide this capability with extremely small SWAP impacts. Years-long operational lifetimes enable flexible, autonomous environmental monitoring during lengthy intervals between and unprecedented situational awareness during crewed missions. Software integration of the localization system into the JSC RFID sensing platform was advanced, but the COVID-19 pandemic complicated and slowed maturation of the localization system SBIR product, and center closure indefinitely deferred a final hardware integration and system demonstration. In the meantime, progress was made to mature the air-quality sensing platform for flight, including hardware, software, antenna, and mechanical improvements. The underlying RFID sensing capability was also adapted to a drawer motion sensing system, which is currently (FY21) being taken toward an ISS flight demonstration as part of the RFID Enhanced Autonomous Logistics Management (REALM)-3 experiment.

Raymond Summers Wagner↗

Establishment of quality, reliability and design standards for low, medium, and high power microwave hybrid microcircuits

Quality, reliability, and design standards for microwave hybrid microcircuits were established. The MSFC Standard 85M03926 for hybrid microcircuits was reviewed and modifications were generated for use with microwave hybrid microcircuits. The results for reliability tests of microwave thin film capacitors, transistors, and microwave circuits are presented. Twenty-two microwave receivers were tested for 13,500 unit hours. The result of 111,121 module burn-in and operating hours for an integrated solid state transceiver module is reported.

Robinson, E. A.↗

Longitudinal handling qualities during approach and landing of a powered lift STOL aircraft

Longitudinal handling qualities evaluations were conducted on the Ames Research Center Flight Simulator for Advanced Aircraft (FSAA) for the approach and landing tasks of a powered lift STOL research aircraft. The test vehicle was a C-8A aircraft modified with a new wing incorporating internal blowing over an augmentor flap. The investigation included: (1) use of various flight path and airspeed control techniques for the basic vehicle; (2) assessment of stability and command augmentation schemes for pitch attitude and airspeed control; (3) determination of the influence of longitudinal and vertical force coupling for the power control; (4) determination of the influence of pitch axis coupling with the thrust vector control; and (5) evaluations of the contribution of stability and command augmentation to recovery from a single engine failure. Results are presented in the form of pilot ratings and commentary substantiated by landing approach time histories.

Franklin, J. A.↗

A Control Law Design Method Facilitating Control Power, Robustness, Agility, and Flying Qualities Tradeoffs: CRAFT

A multi-input, multi-output control law design methodology, named "CRAFT", is presented. CRAFT stands for the design objectives addressed, namely, Control power, Robustness, Agility, and Flying Qualities Tradeoffs. The methodology makes use of control law design metrics from each of the four design objective areas. It combines eigenspace assignment, which allows for direct specification of eigenvalues and eigenvectors, with a graphical approach for representing the metrics that captures numerous design goals in one composite illustration. Sensitivity of the metrics to eigenspace choice is clearly displayed, enabling the designer to assess the cost of design tradeoffs. This approach enhances the designer's ability to make informed design tradeoffs and to reach effective final designs. An example of the CRAFT methodology applied to an advanced experimental fighter and discussion of associated design issues are provided.

Murphy, Patrick C.↗

Integrating air quality and health considerations into power sector decarbonization strategies

Climate change and public health are two interconnected societal challenges. Curbing fossil-based electricity generation reduces the emissions of both CO 2 and air pollutants, which brings tangible health benefits from improved air quality. The potential health benefits from decarbonizing the grid are enormous, immediate, and widespread. From renewable portfolio standards to carbon market, the health co-benefits from clean electricity policies often outweigh their policy costs. As climate action goes local, framing decarbonization around health benefits also makes it more personally relevant and economically attractive. Yet, to date, the health impacts have largely been viewed as ancillary benefits from decarbonization, rather than as a core consideration when energy strategies are formed, assessed and implemented. When strategic choices are made about retiring old infrastructure and building new ones, bringing public health to the center of the discussion can generate greater health benefits with more equitable distribution. Here we identify concrete ways to incorporate air quality and health considerations into power sector decarbonization strategies. We draw insights mainly from empirical and modeling evidence for the United States. These insights are generally applicable and could guide health-oriented decarbonization efforts in other countries as well.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Automated Algorithms for Screening Electronic Parts for Aging using Power Spectra Analysis (PSA) Data

Understanding the age of semiconductor parts being built into devices and systems is of interest for manufacturing quality control. Power spectrum analysis (PSA) is a fast, non-destructive, sensitive method for examining semiconductor parts. This talk will cover the use of multivariate analysis on both PSA data and conventional current-voltage data generated prior to PSA analysis to create algorithms that can be automated to screen semiconductor parts for aging.

Multari, Rosalie A↗

An evaluation of helicopter noise and vibration ride qualities criteria

Two methods of quantifying helicopter ride quality; absorbed power for vibration only and the NASA ride comfort model for both noise and vibration are discussed. Noise and vibration measurements were obtained on five operational US Army helicopters. The data were converted to both absorbed power and DISC's (discomfort units used in the NASA model) for specific helicopter flight conditions. Both models indicate considerable variation in ride quality between the five helicopters and between flight conditions within each helicopter.

Hammond, C. E.↗

Qualification and Issues with Space Flight Laser Systems and Components

The art of flight quality solid-state laser development is still relatively young, and much is still unknown regarding the best procedures, components, and packaging required for achieving the maximum possible lifetime and reliability when deployed in the harsh space environment. One of the most important issues is the limited and unstable supply of quality, high power diode arrays with significant technological heritage and market lifetime. Since Spectra Diode Labs Inc. ended their involvement in the pulsed array business in the late 1990's, there has been a flurry of activity from other manufacturers, but little effort focused on flight quality production. This forces NASA, inevitably, to examine the use of commercial parts to enable space flight laser designs. System-level issues such as power cycling, operational derating, duty cycle, and contamination risks to other laser components are some of the more significant unknown, if unquantifiable, parameters that directly effect transmitter reliability. Designs and processes can be formulated for the system and the components (including thorough modeling) to mitigate risk based on the known failures modes as well as lessons learned that GSFC has collected over the past ten years of space flight operation of lasers. In addition, knowledge of the potential failure modes related to the system and the components themselves can allow the qualification testing to be done in an efficient yet, effective manner. Careful test plan development coupled with physics of failure knowledge will enable cost effect qualification of commercial technology. Presented here will be lessons learned from space flight experience, brief synopsis of known potential failure modes, mitigation techniques, and options for testing from the system level to the component level.

Ott, Melanie N.↗

Qualification and Issues with Space Flight Laser Systems and Components

The art of flight quality solid-state laser development is still relatively young, and much is still unknown regarding the best procedures, components, and packaging required for achieving the maximum possible lifetime and reliability when deployed in the harsh space environment. One of the most important issues is the limited and unstable supply of quality, high power diode arrays with significant technological heritage and market lifetime. Since Spectra Diode Labs Inc. ended their involvement in the pulsed array business in the late 199O's, there has been a flurry of activity from other manufacturers, but little effort focused on flight quality production. This forces NASA, inevitably, to examine the use of commercial parts to enable space flight laser designs. System-level issues such as power cycling, operational derating, duty cycle, and contamination risks to other laser components are some of the more significant unknown, if unquantifiable, parameters that directly effect transmitter reliability. Designs and processes can be formulated for the system and the components (including thorough modeling) to mitigate risk based on the known failures modes as well as lessons learned that GSFC has collected over the past ten years of space flight operation of lasers. In addition, knowledge of the potential failure modes related to the system and the components themselves can allow the qualification testing to be done in an efficient yet, effective manner. Careful test plan development coupled with physics of failure knowledge will enable cost effect qualification of commercial technology. Presented here will be lessons learned from space flight experience, brief synopsis of known potential failure modes, mitigation techniques, and options for testing from the system level to the component level.

Ott, Melanie N.↗

Analysis and design of DC-link capacitor in cascaded H-bridge multilevel active front-end converter

Medium-voltage grid-tied systems often use a cascaded H-bridge multi-level active front-end. In this converter, dc link bus capacitors play an important role in stabilizing the converter and enabling both active and reactive power injections. The present work provides analytical expressions for the capacitor current, which are essential for optimizing system design (especially capacitor size vs. lifetime). Then, the expression is incorporated into the grid connected bidirectional power system model. Consequently, this work contributes to the guiding principles to choose accurate dc link capacitor ratings against grid-side power delivery requirements. DC-link capacitors come with an expiration date which is dependent on the operating power and voltage values. Lack of information about the lifetime of the dc-link capacitor creates uncertainty in the duration of online operation of the converter, thus increasing the probability of a contingency outage. The lifetime of the capacitor can range from only a few seconds of online operation of the station due to under-sizing, to a compromised quality of power flowing through other solid state devices which may not have been designed for the transients that are caused by over-sizing of the dc-link capacitor. A better estimate of the lifetime of these capacitors can help maximize usage and maintain scheduled outages more efficiently, without disruption in service.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Electrical Systems of Pumped Storage Hydropower Plants: Electrical Generation, Machines, Power Electronics, and Power Systems

Adjustable-speed (AS) pumped storage hydropower (PSH) technology has the potential to become a large, consistent contributor to grid stability enabling higher penetrations of wind and solar energy on the future U.S. power system. AS-PSH has high-value characteristics, such as fast response to provide ancillary services to the grid, because it is a power converter interface with the grid (like battery storage), but at the same time it has the energy content large enough to supply both short-term (seconds-to-minutes) and long-term (minutes-to-hours) of energy needs, like more conventional power plants. However, designs must be optimized to lower the capital expenditure (CapEx) and to provide a high-quality grid interface capability (e.g. power quality, ancillary service provider, fault-tolerant or fault ride-through capability), which is a primary factor in the acceptance of AS-PSH into a utility’s generation mix. This CapEx will be greatly affected by the cost savings associated with the civil structure, turbine design, power electronics, control systems, or unique generator designs. A holistic design must be considered to get a full picture of the benefits of the technology proposed. The AS-PSH can be controlled to reduce the impact of transient disturbance on a power system and at the same time can be controlled to minimized subsequent component fatigue and potential oscillation modes within the plant, with the overall impact in reducing the operational expenditures (OpEx).Generating clean power to meet standards such as Institute of Electrical and Electronics Engineers (IEEE) 519 and International Electrotechnical Commission (IEC) 1000-3-2 will be a continuing challenge. For many technology developers, however, improved AS-PSH technologies will become a key component of generator-storage systems of the future given the prospects of increased performance and decreasing costs, and the ever-increasing penetration of renewables (e.g wind power and solar power).

13 HYDRO ENERGY↗

Wintertime Overnight NOx Removal in a Southeastern United States Coal-Fired Power Plant Plume: A Model for Understanding Winter NOx Processing and Its Implications

Nitric oxide (NO) is emitted in large quantities from coal-burning power plants. During the day, the plumes from these sources are efficiently mixed into the boundary layer, while at night, they may remain concentrated due to limited vertical mixing during which they undergo horizontal fanning. At night, the degree to which NO is converted to HNO3 and therefore unable to participate in next-day ozone (O3) formation depends on the mixing rate of the plume, the composition of power plant emissions, and the composition of the background atmosphere. In this study, we use observed plume intercepts from the Wintertime INvestigation of Transport, Emissions and Reactivity (WINTER) campaign to test sensitivity of overnight NOx removal to the N2O5 loss rate constant, plume mixing rate, background O3, and background levels of volatile organic compounds using a 2-D box model of power plant plume transport and chemistry. The factor that exerted the greatest control over NOx removal was the loss rate constant of N2O5. At the lowest observed N2O5 loss rate constant, no other combination of conditions converts more than 10 percent of the initial NOx to HNO3. The other factors did not influence NOx removal to the same degree.

air quality↗

Harmonic Modeling, Data Generation and Analysis of Power Electronics-Interfaced Residential Loads

The share of electronics-based residential load is expected to rise as devices such as variable frequency drives (VFDs), electric vehicle chargers, and inverter-based distributed energy resources (DERs), e.g., photovoltaic (PV) systems become more common. These loads may introduce significant harmonics into power networks that need to be closely studied in order to perform accurate load modeling and forecasting. However, it can be difficult to obtain harmonic-rich voltage and current data - necessary for identifying accurate load models - for residential electrical loads. Recognizing this need, we identify and model a set of electronics-based end-use loads and DERs in an electromagnetic transients program (EMTP) tool for a residence with a single- phase split-phase supply. Further, a procedure is developed to model harmonic interactions between end-use loads connected to the same non-ideal supply voltage in a residential setting. Finally, a harmonic-rich dataset produced via the proposed procedure is utilized to identify frequency coupling matrix (FCM) based load model. Numerical results demonstrate the accuracy of the model, and explore model identifiability with limited data points.

harmonics, power quality, load modeling↗

Modeling and Impact of Hyperloop Technology on the Electricity Grid

This paper provides an overview of hyperloop technologies, including a brief discussion of key components of a hyperloop system that determine the electric power requirements as a function of time. At-scale hyperloop systems do not yet exist, so a model was used to generate a set of load profiles for conceptual hyperloop realizations at four locations in the United States: two systems in California and one each in Colorado and Ohio. In all four cases, the modeled hyperloop load profiles included pulses in both active and reactive power. Grid modeling was performed to estimate the grid impacts and for dis-cussing grid integration challenges. The paper discusses how energy storage systems might be used to eliminate the pulsating load characteristics or significantly reduce it to accommodate current grid planning guidelines

24 POWER TRANSMISSION AND DISTRIBUTION↗