Engineering Commons^™

Flatness-Based Control Methodologies To Improve Frequency Regulation In Power Systems With High Penetration Of Wind, Maryam Hassani Variani

Doctoral Dissertations

To allow for high penetration of distributed generation and alternative energy units, it is critical to minimize the complexity of generator controls and to minimize the need for close coordination across regions. We propose that existing controls be replaced by a two-tier structure of local control operating within a global context of situational awareness. Flatness as an extension of controllability for non-linear systems is a key to enabling planning and optimization at various levels of the grid in this structure. In this study, flatness-based control for: one, Automatic Generation Control (AGC) of a multi-machine system including conventional generators; and two, …

Development And Modeling Of A Biosensor Platform Using Algan/Gan Hemt Devices, Fahmida Shaheen Tulip

Doctoral Dissertations

The history of biosensors began in 1962 with the invention of enzyme electrodes by Leland C. Clark. Since then, biosensors have come a long way with simultaneous contributions in various fields such as biology, chemistry, material science, electronics, physics and VLSI. With the advancement in science and technology, smaller, more sensitive and dependable biosensors have become a reality. Still the need for cost-effective, sophisticated, reliable, robust biosensors that can be used to detect multiple types of biomolecules remains a technological challenge to be resolved.

The proposed AlGaN/GaN High Electron Mobility Transistors (HEMTs) have excellent prospect to become the biosensor platform …

Lifetime Estimation Of Igbts In A Grid-Connected Statcom, Lakshmi Reddy Gopi Reddy

Doctoral Dissertations

Lifetime estimation of power semiconductor devices, and IGBT devices in particular, used in the power electronics integrated with power systems has gained technical importance in recent times with increased scope of distributed generation, renewable energy systems and FACTS. Since most of the common failures (wire bond and solder fatigue) are caused by thermo-mechanical stresses, the methodology of lifetime estimation starts with temperature estimation, cycle counting based on rainflow algorithm, and finally degradation calculation based on linear accumulation model.

Different number of RC cells for each packaging layer in the module for the thermal model, including the influence of encapsulant is …

Elucidating Fundamental Mechanisms In Focused Electron- And Ion-Beam Induced Synthesis, Carlos M. Gonzalez

Doctoral Dissertations

A focused electron beam deposition process (FEBID) coupled with in-situ infrared pulsed laser assist (LA-EBID) has been implemented for higher purity tungsten nanowires using W(CO)₆ [tungsten hexacarbonyl] as parent precursor gas. Nanowires made of Co from Co₂(CO)₈ [dicobalt octacarbonyl] and Pt from MeCpPtIVMe₃ [trimethyl methylcyclopentadienyl platinum] have also been realized by using inert focused ion beams of helium and helium and neon, respectively. In all cases, higher electrical conductivities, higher purities and larger grain sizes have been obtained when compared with preceding traditional additive edit techniques. These new approaches will make possible successful nanoscale direct-write …

Computing Approximate Solutions To The Art Gallery Problem And Watchman Route Problem By Means Of Photon Mapping, Bruce Andrew Johnson

Doctoral Dissertations

Wireless sensor networks (WSNs) can be partitioned component sensor nodes (SNs) who are meant to operate and sense information arriving from multiple spectra in their environment. Determining where to place a single SN or multiple SNs such that the amount of information gained is maximized while the number of SNs used to gain that information is minimized is an instance of solving the art gallery problem (AGP). In order to solve the AGP, we present the Sensor Placement Optimization via Queries (SPOQ) algorithm that uses level sets populated by queries to a photon map in order to find observation points …

Uwb Precise Indoor Localization System Performance, Limitations And Its Integration, Essam Abdelkadir Elkhouly

Doctoral Dissertations

An indoor localization system that was built at University of Tennessee is extensively studied and improved. The goal of the system is to achieve mm down to sub-mm accuracy/precision.

Sub-sampling is used to alleviate the high sampling rate required for UWB signals. Current commercial direct sampling systems are still too slow or prohibitively expensive for UWB applications. We developed two different sub-sampling techniques, but the two systems suffer numerous shortcomings: low throughput, non-robustness, non-linearity. A third system is introduced that achieve both high accuracy and high through-put. Changes in the detection algorithm and the frame synchronization are developed to accommodate …

High-Efficiency Three-Phase Current Source Rectifier Using Sic Devices And Delta-Type Topology, Ben Guo

Doctoral Dissertations

In this dissertation, the benefits of the three-phase current source rectifier (CSR) in high power rectifier, data center power supply and dc fast charger for electric vehicles (EV) will be evaluated, and new techniques will be proposed to increase the power efficiency of CSRs.

A new topology, referred as Delta-type Current Source Rectifier (DCSR), is proposed and implemented to reduce the conduction loss by up to 20%. By connecting the three legs in a delta type on ac input side, the dc-link current in DCSR can be shared by two legs at the same time.

To increase the switching speed …

A Low-Power, Reconfigurable, Pipelined Adc With Automatic Adaptation For Implantable Bioimpedance Applications, Terence Cordell Randall

Doctoral Dissertations

Biomedical monitoring systems that observe various physiological parameters or electrochemical reactions typically cannot expect signals with fixed amplitude or frequency as signal properties can vary greatly even among similar biosignals. Furthermore, advancements in biomedical research have resulted in more elaborate biosignal monitoring schemes which allow the continuous acquisition of important patient information. Conventional ADCs with a fixed resolution and sampling rate are not able to adapt to signals with a wide range of variation. As a result, reconfigurable analog-to-digital converters (ADC) have become increasingly more attractive for implantable biosensor systems. These converters are able to change their operable resolution, sampling …

Adaptive Control For Power System Voltage And Frequency Regulation, Yao Xu

Doctoral Dissertations

Variable and uncertain wind power output introduces new challenges to power system voltage and frequency stability. To guarantee the safe and stable operation of power systems, the control for voltage and frequency regulation is studied in this work.

Static Synchronous Compensator (STATCOM) can provide fast and efficient reactive power support to regulate system voltage. In the literature, various STATCOM control methods have been discussed, including many applications of proportional–integral (PI) controllers. However, these previous works obtain the PI gains via a trial and error approach or extensive studies with a tradeoff of performance and applicability. Hence, control parameters for the …

Frequency Monitoring Network (Fnet) Data Center Development And Data Analysis, Ye Zhang

Doctoral Dissertations

Frequency Monitoring Network (FNET) is an Internet-based, wide-area phasor measurement system that collects power system data using Frequency Disturbance Recorders (FDRs) that are installed at the distribution level. The FNET data center enables the monitoring of bulk power systems, and provides wide-area situational awareness and disturbance analysis for understanding power system disturbances and system operations. Therefore, the data center plays a very critical role in the entire FNET system framework.

In recent years, many potential challenges brought by the rapid expansion of the FNET system have underlined the importance of designing the next-generation FNET data center. More discussions about the …

High Density Emi Filter Design In High Power Three-Phase Motor Drive Systems, Jing Xue

Doctoral Dissertations

High density EMI filter is important in the application of more-electric-aircraft (MEA). In this work, the author is focusing on several major aspects of EMI filter design that would influence the power density.

In Chapter 1, the feature of EMI study and conventional design methods are reviewed.

The interaction between the common-mode (CM) and differential-mode (DM) noise is one key factor introducing unnecessary weight to EMI filter design. In Chapter 2, the author explains the origin of the mixed-mode (MM) noise on the output side of three-phase motor drives. Experimental results have verified the existence of the MM noise in …

In-Line Microfluidic Particle Preconcentrator And Detector For Continuous Flow Monitoring, Quan Yuan

Doctoral Dissertations

This dissertation presents the design and prototyping of three in-line microfluidic devices for continuous monitoring of particulate flows. The three devices are AC electrokinetic (ACEK) and acoustic sample preconcentration techniques for resettable particle enrichment, and an in-line somatic cell counter for mastitis monitoring.

For the ACEK preconcentrator, ACEK is a new and promising technique to manipulate micro/bio-fluid and particles. There are many advantages over other techniques, such as low applied voltage, low cost, portability and notable biocompatibility of lab-on-a-chip (LOC) device. We successfully developed a 3D multi-level electrode platform to extract bioparticles via AC electroosmosis (ACEO) and negative Dielectrophoresis (DEP). …

Cascaded Inverters For Grid-Connected Photovoltaic Systems, Bailu Xiao

Doctoral Dissertations

With the extraordinary market growth in grid-connected PV systems, there is increasing interests in grid-connected PV inverters. Focus has been placed on cheap, high-efficiency, and innovative inverter solutions, leading to a high diversity within the inverters and new system configurations. This dissertation chooses cascaded multilevel inverter topologies for grid-connected PV systems to reduce the cost and improve the efficiency.

First, a single-phase cascaded H-bridge multilevel PV inverter is discussed. To maximize the solar energy extraction of each PV string, an individual maximum power point tracking (MPPT) control scheme is applied, which allows independent control of each dc-link voltage. A generalized …

Generation Scheduling For Power Systems With Demand Response And A High Penetration Of Wind Energy, Guodong Liu

Doctoral Dissertations

With renewable energy sources and demand response programs expanding in many power systems, traditional unit commitment and economic dispatch approaches are inadequate. The power system is changing to one where there is control with uncertainty for both generation and load. Alternative power system scheduling methods capable of aggregating the uncertainty of wind power and demand response, while maintaining reliable and economic performance are investigated in this work. The research addresses four aspects of these changes.

First, a probabilistic method is proposed to maintain uniform system reliability level in the hour-ahead economic dispatch by quantifying different levels of required spinning reserve. …

Studies Of Economics And Stability With Variable Generation And Controllable Load, Hao Huang

Doctoral Dissertations

This work probes several aspects of the renewable resources and controllable loads. The investigation includes the impact of wind power in bidding process in a deregulated power market, the effect of load damping elements on power system frequency stability and security, and impact of controllable load on system operation from the viewpoint of economic volatility and physical security.

In the first part, new bidding models are developed under two schemes for wind generation to analyze the competition among generation companies (GENCOs) with transmission constraints considered. The proposed method employs the supply function equilibrium (SFE) to model a GENCO’s bidding strategy. …

Modeling, Analysis, And Control Of A Mobile Robot For In Vivo Fluoroscopy Of Human Joints During Natural Movements, Matthew A. Young

Doctoral Dissertations

In this dissertation, the modeling, analysis and control of a multi-degree of freedom (mdof) robotic fluoroscope was investigated. A prototype robotic fluoroscope exists, and consists of a 3 dof mobile platform with two 2 dof Cartesian manipulators mounted symmetrically on opposite sides of the platform. One Cartesian manipulator positions the x-ray generator and the other Cartesian manipulator positions the x-ray imaging device. The robotic fluoroscope is used to x-ray skeletal joints of interest of human subjects performing natural movement activities. In order to collect the data, the Cartesian manipulators must keep the x-ray generation and imaging devices accurately aligned while …

An Analog Vlsi Deep Machine Learning Implementation, Junjie Lu

Doctoral Dissertations

Machine learning systems provide automated data processing and see a wide range of applications. Direct processing of raw high-dimensional data such as images and video by machine learning systems is impractical both due to prohibitive power consumption and the “curse of dimensionality,” which makes learning tasks exponentially more difficult as dimension increases. Deep machine learning (DML) mimics the hierarchical presentation of information in the human brain to achieve robust automated feature extraction, reducing the dimension of such data. However, the computational complexity of DML systems limits large-scale implementations in standard digital computers. Custom analog signal processing (ASP) can yield much …