Engineering Commons^™

Power System State Estimation Using Phasor Measurement Units, Jiaxiong Chen

Theses and Dissertations--Electrical and Computer Engineering

State estimation is widely used as a tool to evaluate the real time power system prevailing conditions. State estimation algorithms could suffer divergence under stressed system conditions. This dissertation first investigates impacts of variations of load levels and topology errors on the convergence property of the commonly used weighted least square (WLS) state estimator. The influence of topology errors on the condition number of the gain matrix in the state estimator is also analyzed. The minimum singular value of gain matrix is proposed to measure the distance between the operating point and state estimation divergence.

To study the impact of …

Power Control Of Single-Stage Pv Inverter For Distribution System Volt-Var Optimization, Xiao Liu

Theses and Dissertations--Electrical and Computer Engineering

The output power variability of intermittent renewable sources can cause significant fluctuations in distribution system voltages. A local linear controller that exploits the capability of a photovoltaic inverter to provide both real and reactive power is described. This controller substitutes reactive power for real power when fluctuations in the output of the photovoltaic source are experienced. In this way, the inverter can help mitigate distribution system voltage fluctuations. In order to provide real and reactive to the grid, a three-phase grid-connected single-stage photovoltaic system with maximum power point tracking and power control is described. A method of reducing the current …

Contingency Analysis Of Power Systems In Presence Of Geomagnetically Induced Currents, Sivarama Karthik Vijapurapu

Theses and Dissertations--Electrical and Computer Engineering

Geomagnetically induced currents (GIC) are manifestations of space weather phenomena on the electric power grid. Although not a new phenomenon, they assume great importance in wake of the present, ever expanding power grids. This thesis discusses the cause of GICs, methodology of modeling them into the power system and the ramifications of their presence in the bulk power system. GIC is treated at a micro level considering its effects on the power system assets like Transformers and also at a macro level with respect to issues like Voltage instability. In illustration, several simulations are made on a transformer & the …

Walkcompass: Finding Walking Direction Leveraging Smartphone's Inertial Sensors, Nirupam Roy

Theses and Dissertations

Determining moving direction with smartphone's inertial sensors is a well known problem in the field of location service. Compass alone cannot solve this problem because smartphone's compass cannot achieve high accuracy. Moreover GPS is not suitable in indoor scenario. Another well known approach is dead-reckoning but dead-reckoning needs to know phones initial orientation and over time it keeps accumulating errors and after some time the estimation becomes to noisy to use. To overcome these limitations, we propose a solution called WalkCompass which is specially designed for pedestrians keeping in mind the variation of force during normal human walk. Therefore the …

Removal Of Synthetic Organic Compounds And Nom By Single-Walled Carbon Nanotubes-Ultrafiltration And Forward Osmosis Membrane System, Jiyong Heo

Theses and Dissertations

This overall theme of this dissertation is to investigate the potential engineered application of low pressure membranes incorporated with single-walled carbon nanotubes (SWNTs) and forward osmosis (FO) membrane systems for the removal of synthetic organic compounds (SOCs) and natural organic matter (NOM) from drinking water sources. The focus is on the use of SWNTs-ultrafiltration (UF) and FO membrane systems to facilitate the removal of these compounds and potential applications of these membrane system designs for reducing the energy demands and membrane fouling in environmental water filtration process and seawater desalination. The SWNTs-UF results indicate that SOCs transport is influenced by …

Advanced Fuels Modeling: Evaluating The Steady-State Performance Of Carbide Fuel In Helium-Cooled Reactors Using Frapcon 3.4, Luke H. Hallman

Theses and Dissertations

Uranium carbide (UC) has long been considered a potential alternative to uranium dioxide (UO2) fuel, especially in the context of Gen IV gas-cooled reactors. It has shown promise because of its high uranium density, good irradiation stability, and especially high thermal conductivity. Despite its many benefits, UC is known to swell at a rate twice that of UO2. However, the swelling phenomenon is not well understood, and we are limited to a weak empirical understanding of the swelling mechanism.

One suggested cladding for UC is silicon carbide (SiC), a ceramic that demonstrates a number of desirable properties. Among them are …

Fault Aware Soft Restart Of An Islanded Microgrid Using An Inverter Coupled Energy Storage System, Asif Anwar

Theses and Dissertations

This research developed a method for autonomous operation of an inverter-coupled energy storage system for safe islanding- re-energization - and reconnection of the facility-island or microgrid to the utility / distribution circuit in a seamless manner in the event of a fault. This enables the energy storage system to function as an autonomous source within the utility power distribution system without the need to re-engineer the existing protection coordination in the distribution system. Fault detection based on voltage measurements from the inverter terminals are used to detect a fault and isolate the energy storage-powered facility with negligible power feed into …

Analysis Of Modulation And Voltage Balancing Strategies For Modular Multilevel Converters, Ryan Blackmon

Theses and Dissertations

Modular multilevel converters are an emerging voltage source converter topology suitable for many applications. The increased utilization of HVDC power transmission solutions has resulted in modular multilevel converters becoming a more common converter type. Other applications include interfacing renewable energy power sources to the grid and motor drives. Modular multilevel converters are beneficial for medium voltage motor drives because the properties of this converter topology, such as low distortion, allow for an efficient motor drive design.

Modular multilevel converters are designed where instead of using 6 IGBTs as in a conventional voltage source converter, numerous low-rated IGBTs are used to …

High Performance Rf Control Devices Using Capacitively Coupled Contacts (C3) Over Iii-N Heterostructures, Faisal Jahan

Theses and Dissertations

RF switches, power limiters and other control devices are essential components of modern RF systems. RF switches are important parts of wireless modules of various devices such as laptops, tablets, cell phones etc. and key components of satellites communication systems, radars, multi-band wireless and aerospace communications, phased array antennas. RF Power limiters (PL) are also important components of RF systems protecting linear amplifiers, detectors etc. from high-power stress. Traditionally, RF switches are fabricated using pin diodes or MEMS, Si MOSFETs or GaAs HEMTs. RF PLs are typically implemented using Schottky or pin-diodes. Traditional devices used in RF switch and PLs …

Application Of Agent-Based Approaches To Enhance Container Terminal Operations, Omor Sharif Abul Bashar Mohammad

Theses and Dissertations

Queuing at marine terminal gates has long been identified as a source of emissions and high drayage costs due to the large number of trucks idling. The first study in this dissertation addresses queuing of trucks at marine terminal gates and presents a novel agent-based framework where the drayage companies can minimize congestion by using the provided real-time gate queuing information. The problem was tackled based on the approach of El Farol Bar problem from game theory. Our proposed model can be used as a means of managing demand for the marine terminals, assuming that drayage firms will adjust their …

Bs News January/February

Building Services Engineering

No abstract provided.

Frequency Characterization Of Si, Sic, And Gan Mosfets Using Buck Converter In Ccm As An Application, Keshava Gopalakrishna

Browse all Theses and Dissertations

Present day applications using power electronic converters are focusing towards improving the speed, efficiency, and robustness. This led to the implementation of new devices in such converters where speed and efficiency are of concern. As silicon (Si) based power devices are approaching their operational performance limits with respect to speed, it is essential to analyze the properties of new devices, which are capable of replacing silicon based devices. Wide band-gap (WBG) semiconductor materials such as silicon carbide (SiC) and gallium nitride (GaN) are such materials, whose material properties show promising advantages for power electronic applications.

This thesis focuses on the …

Fabrication And Mass Transport Analysis Of Tape Cast Nano-Silver High Temperature Solder, Jared Ray Mccoppin

Browse all Theses and Dissertations

The principal objective in this research was to develop a die attach method to facilitate the use of wide band gap semiconductors in high-temperature environments, and study fundamental mass transport in nano-initiated die attach microstructure at high temperature. Low temperature sintering silver-nano-pastes have been demonstrated as an effective method for die attach by other groups. Fabrication and optimization of the die attach method in this work was accomplished via tape casting. A novel binder system and a bimodal particle distribution were utilized. The tape casting method allowed die attach materials to be pre-stressed. Fundamental understanding of creep deformation process and …

Utility Of A Volume-Regulated Drive System For Direct Mechanical Ventricular Actuation, Benjamin A. Schmitt

Browse all Theses and Dissertations

Direct Mechanical Ventricular Actuation (DMVA) is a non-blood contacting cardiac assist device that augments ventricular function. The purpose of this study was to determine if a volume-regulated "hand pump" drive system and a pressure-regulated "switch tank" drive system provide equivalent levels of cardiac support. Canine (n=2) and swine (n=4) were instrumented for hemodynamic monitoring and intravascular echocardiography. DMVA support was assessed during both severe heart failure and fibrillation. Pump function was evaluated using hemodynamic measures to calculate stroke work. Myocardial function was assessed using echocardiographic speckle tracking to quantify strain rate. Results were compared between groups using paired t-tests. There …

Assessing The Effects Of Multi-Modal Communications On Mental Workload During The Supervision Of Multiple Unmanned Aerial Vehicles, Sharon Claxton Bommer

Browse all Theses and Dissertations

Human supervisory control (HSC) systems that require intermittent human input of commands to create actions within the system are helpful in reducing the human's mental workload (MWL). HSC systems are commonly employed in the piloting and control of unmanned aerial vehicles (UAVs). As the ratio of UAVs to operators increases there is a clear need to understand the effort required to complete task requirements. Specifically, this research explored MWL relative to multi-modal communications using subjective and physiological measures. To accomplish this, a cognitive model was developed to understand the relationship between tasks and MWL. MWL was manipulated by measuring three …

Application Of The Augmented Operator Function Model For Developing Performance Metrics In Persistent Surveillance, Tiffany M. Paul

Browse all Theses and Dissertations

Difficulties with the implementation of persistent Wide Area Motion Imagery (WAMI) sensors to support real-time military missions have risen within Intelligence, Surveillance, and Reconnaissance organizations. In this study, cognitive models were developed of operators performing real-time missions currently supported by narrow field of view Full Motion Video (FMV) and WAMI sensors. These models were used in conjunction with a cognitive task analysis, creating an augmented operator function model (OFM-COG). This thesis describes the OFM-COG and demonstrates how this model-based analysis technique can document the cognitive implications of persistent surveillance with motion imagery. The analytic procedures required to build this model …

Bacillus Thuringiensis: Transgenic Crops, Julie A. Peterson, John J. Obrycki, James D. Harwood

Department of Entomology: Faculty Publications

Bacillus thuringiensis (Bt) crops, genetically modified to express insecticidal toxins that target key pests of corn, cotton, rice, potato, and other crops, have been rapidly adopted and have become dominant fixtures in agroecosystems throughout the world. Due to the constitutive nature of Bt toxin expression, insecticidal proteins may be found in nearly all plant tissues, presenting multiple sources for Bt toxins to enter the environment, thus creating complex direct and indirect pathways for non-target organisms to be exposed to insecticidal proteins. The environmental impacts of Bt crops have been widely debated, although both benefits and risks do exist. Benefits of …

Human Performance Regression Testing, Amanda Swearngin, Myra B. Cohen, Bonnie E. John, Rachel K. E. Bellamy

School of Computing: Conference and Workshop Papers

As software systems evolve, new interface features such as keyboard shortcuts and toolbars are introduced. While it is common to regression test the new features for functional correctness, there has been less focus on systematic regression testing for usability, due to the effort and time involved in human studies. Cognitive modeling tools such as CogTool provide some help by computing predictions of user performance, but they still require manual effort to describe the user interface and tasks, limiting regression testing efforts. In recent work, we developed CogTool-Helper to reduce the effort required to generate human performance models of existing systems. …

Fea Estimation And Experimental Validation Of Solid Rotor And Magnet Eddy Current Loss In Single-Sided Axial Flux Permanent Magnet Machines, Xu Yang, Dean Patterson, Jerry Hudgins, Jessica Colton

Department of Electrical and Computer Engineering: Faculty Publications

The rotor and magnet loss in single-sided axial flux permanent magnet machines with non-overlapped windings is studied in this paper. FEA estimations of the loss are carried out using both 2-D and 3-D modeling. The rotor and magnet losses are determined separately for stator slot passing and MMF space harmonics from currents in the stator. The segregation of loss between the solid rotor plate and the magnet is addressed. The eddy current loss reduction by magnet segments is discussed as well. The prototype 24 slot/22 pole single-sided AFPMs, fabricated with both single layer and double layer windings are assembled. Methods …

Multi-Objective Design Optimization Of A Single-Sided Axial Flux Permanent Magnet Machine, Xu Yang, Dean Patterson, Jerry Hudgins

Department of Electrical and Computer Engineering: Faculty Publications

This paper presents an optimal design approach for a single-sided axial flux permanent magnet (AFPM) machine. A multi-objective differential evolution based optimization algorithm is implemented, which is to maximize the output torque density (Nm/kg) and efficiency. Design constraints including geometrical and operating limits are considered. Total of seven independent variables are employed in the design. Optimization results are compared with a prototype design.

Trading Wind Power In A Competitive Electricity Market Using Stochastic Programing And Game Theory, Ting Dai, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

Wind power is one of the most rapidly growing clean and renewable energy sources. However, due to the uncertainty and intermittency of wind power, the increasing penetration of wind power into the electric power system will pose challenges to power system operators. Moreover, as a participant in a competitive electricity market, a wind power producer’s behavior and profit will be influenced by other participants’ behaviors. This paper proposes a model of using stochastic programming to generate optimal bidding strategies to maximize the total profits of wind and conventional power producers in both the energy market and a bilateral reserve market, …

Application-Aware Routing For Multi-Hop Cognitive Radio Networks With Channel Bonding, Feng Ye, Jiazhen Zhou, Rose Qingyang Hu

Department of Electrical and Computer Engineering: Faculty Publications

Due to the unequal spectrum resources in different areas, multi-hop wireless cognitive radio network (MWCRN) faces the challenge of a relatively poor performance. In this paper, we propose an application-aware routing scheme with channel bonding technique to help improve the efficiency and performance of a MWCRN network. More specifically, we formulate an optimization problem aiming to meet the application request, as well as operating at low transmission cost. To solve this problem, we first study the greatest lower bound of transmission cost named as Utopian cost, as well as an upper bound of transmission cost. Moreover, we propose two distributed …

Imbalance Fault Detection Of Direct-Drive Wind Turbines Using Generator Current Signals, Xiang Gong, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

No abstract provided.

Short-Term Wind Power Prediction Using A Wavelet Support Vector Machine, Jianwu Zeng, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

No abstract provided.

Reliability-Driven Optimum Standby Electric Storage Allocation For Power Distribution Systems, Salman Kahrobaee, Sohrab Asgarpoor

Department of Electrical and Computer Engineering: Faculty Publications

Integration of distributed energy resources (DER) has become an indispensable aspect of the future smart grid. The significant and valuable impact of these resources is expected to lead toward a more reliable and efficient power system. As the number of distributed generation and storage systems increases, the availability of sensitive and critical loads may be improved by allocating a portion of electricity storage capacity as a reserve. The goal of this paper is to determine the optimum standby storage capacity in a smart grid based on reliability indices such as the Expected Interruption Cost (EIC) of the system using particle …

The Effect Of Demand Side Management On Reliability Of Automated Distribution Systems, Salman Kahrobaee, Sohrab Asgarpoor

Department of Electrical and Computer Engineering: Faculty Publications

Demand side management (DSM) provides power systems with the opportunity to supply electricity to the customers more efficiently and reliably. In a smart grid incorporating automated control and distributed energy systems, an effective DSM can alleviate the peak load and shift part of the demand to off-peak hours. This paper evaluates the impact of DSM on reliability of automated power distribution systems. Unlike the previous research studies, we perform load flow analysis and state enumeration to include actual restrictions of distribution systems such as voltage limits of buses and power flow limits of branches. The effects of demand curve and …

Real-Time Temporal Stereo Matching Using Iterative Adaptive Support Weights, Jedrzej Kowalczuk, Eric T. Psota, Lance C. Pérez

Department of Electrical and Computer Engineering: Faculty Publications

Stereo matching algorithms are nearly always designed to find matches between a single pair of images. A method is presented that was specifically designed to operate on sequences of images. This method considers the cost of matching image points in both the spatial and temporal domain. To maintain real-time operation, a temporal cost aggregation method is used to evaluate the likelihood of matches that is invariant with respect to the number of prior images being considered. This method has been implemented on massively parallel GPU hardware, and the implementation ranks as one of the fastest and most accurate real-time stereo …

A Survey Of Energy-Efficient Compression And Communication Techniques For Multimedia In Resource Constrained Systems, Tao Ma, Michael Hempel, Dongming Peng, Hamid Sharif

Department of Electrical and Computer Engineering: Faculty Publications

Advances in wireless multimedia communication technologies enable new types of pervasive and ubiquitous applications such as mobile health care, environmental monitoring, facility monitoring and traffic surveillance. Among different factors concerned, energy efficiency is one of the most challenging issues in multimedia communication due to the resource constraints, and the requirements for high bandwidth and low transmission delay. In this survey, we provide a broad picture of the state of- the-art energy efficient techniques that have been proposed in wireless multimedia communication for resource-constrained systems such as wireless sensor networks and mobile devices.

Following the essential stages required for multimedia communication, …

Design Considerations Of Switched Reluctance Motors With Bipolar Excitation For Low Torque Ripple Applications, Cong Ma, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

Switched reluctance motors (SRMs) have been applied to many applications over the past decades due to their simple structure, low cost, and robustness. The primary disadvantage of SRMs is the relatively high torque ripple. In this paper, the machine design is considered under a two-mode bipolar excitation to achieve the optimum performance of a mutually coupled switched reluctance motor (MCSRM) for low torque ripple applications. Geometrical design equations and practical challenges are investigated. In addition, a six-slot, tenpole (6/10) SRM with a six-phase winding configuration under the two-mode bipolar excitation is optimized by solving a multiobjective optimization problem using a …

Improved Microcontroller-Based Electronic Respiratory Training, Steven A. Parkison, Jay D. Carlson, Lance C. Pérez

Department of Electrical and Computer Engineering: Faculty Publications

Respiratory training is a critical component of many rehabilitation plans, including those of stroke patients. Many current respiratory training techniques lack efficient methods for quantifying progress and updating testing parameters. A previously-developed microcontroller-based device, designed in conjunction with clinicians at the Institute for Rehabilitation Science and Engineering at Madonna Rehabilitation Hospital, has demonstrated promising results. Here, a prototype of a revised device that is network connected and remoatly sends trial information is presented.\ The proposed device demonstrates enhanced functionality, while being smaller and using less power than the original prototype.