Engineering Commons^™

Analysis And Control Of Vsc Based Hvdc System Under Single-Line-To-Ground Fault Conditions, Xiaojie Shi

Doctoral Dissertations

To take full advantage of multilevel modular converter (MMC) and extend its application in high voltage direct current (HVDC) transmission systems, the ability to deal with severe unbalanced conditions, especially under single-line-to-ground (SLG) fault, is a key requirement.

This dissertation deals with the development of a fault handling strategy, which helps HVDC systems achieve continuous energy supply and desired operation performance under temporary SLG fault conditions while ensuring a smooth and fast black start for MMC-HVDC particularly if the system has to shut down when a permanent SLG fault occurs. Several related research topics will be discussed in this dissertation. …

Characterization Of Optimal Cyber Attacks On Control Systems, Anis Drira

Doctoral Dissertations

Securing control systems which manage the nation's critical physical infrastructures and key resources is becoming one of the highest priorities and can no longer be ignored. Several researches and incidents have confirmed the real vulnerability of these systems. Due to the vital role of control systems, the study and the development of advanced strategies to overcome these cyber-security breaches are very important. Control systems are mainly composed of sensors and actuators, which cyber-security is vital for the security of the whole control system.

Characterizing and guarding against worst case attack scenarios is important to secure control systems. This dissertation proposes …

Three-Phase Power Converter Based Real-Time Synchronous Generator Emulation, Liu Yang

Doctoral Dissertations

To bridge the gap between power system research and their real application in power grids, a Hardware Test-Bed (HTB) with modular three-phase power converters has been developed at the CURENT center, the University of Tennessee, Knoxville, to emulate transmission level power systems with actual power flowing.

This dissertation focuses on the development and verification of a real-time synchronous generator (SG) emulator in the HTB. The research involved in this dissertation aims at designing a proper control to achieve emulator performance goal and investigating the sources of error and its influence on interconnected SG-emulator networks.

First, different interface algorithms (IAs) are …

Energy-Efficient And Power-Dense Dc-Dc Converters In Data Center And Electric Vehicle Applications Using Wide Bandgap Devices, Weimin Zhang

Doctoral Dissertations

The ever increasing demands in the energy conversion market propel power converters towards high efficiency and high power density. With fast development of data processing capability in the data center, the server will include more processors, memories, chipsets and hard drives than ever, which requires more efficient and compact power converters. Meanwhile, the energy-efficient and power-dense converters for the electric vehicle also result in longer driving range as well as more passengers and cargo capacities. DC-DC converters are indispensable power stages for both applications. In order to address the efficiency and density requirements of the DC-DC converters in these applications, …

Wide-Area Synchrophasor Measurement Applications And Power System Dynamic Modeling, Yin Lei

Doctoral Dissertations

The use of synchrophasor measurements system-wide has been providing significant assistance for grid dynamic monitoring, situation awareness and reliability improvement. Frequency Monitoring Network (FNET), as an academia-run synchrophasor measurement system, utilizes a large number of Internet-connected low-cost Frequency Disturbance Recorders (FDRs) installed at the distribution level to measure power system dynamics and provide both online and off-line applications, such as event detection, oscillation modes estimation, event replay, etc. This work aims to further explore applications of the FNET measurements and utilize measurement-based method in dynamic modeling.

Measurement-based dynamic reduction is an important application of synchrophasor measurement, especially considering the fact …

Incentive Based Residential Demand Aggregation, Qinran Hu

Doctoral Dissertations

From the beginning of the twenty-first century, the electrical power industry has moved from traditional power systems toward smart grids. However, with the increasing amount of renewable energy resources integrated into the grid, there is a significant challenge in power system operation due to the intermittency and variability of the renewables. Therefore, the utilization of flexible and controllable demand-side resources to maintain power system efficiency and stability has become a fundamental goal of smart grid initiatives.

Meanwhile, due to the development of communication and sensing technologies, intelligent demand-side management with automatic controls enables residential loads to participate in demand response …

Using Gpu To Accelerate Linear Computations In Power System Applications, Xue Li

Doctoral Dissertations

With the development of advanced power system controls, the industrial and research community is becoming more interested in simulating larger interconnected power grids. It is always critical to incorporate advanced computing technologies to accelerate these power system computations. Power flow, one of the most fundamental computations in power system analysis, converts the solution of non-linear systems to that of a set of linear systems via the Newton method or one of its variants. An efficient solution to these linear equations is the key to improving the performance of power flow computation, and hence to accelerating other power system applications based …

Interface And Morphology Engineering In Solution-Processed Electronic And Optoelectronic Devices, Sanjib Das

Doctoral Dissertations

The first part of this dissertation focuses on interface and morphology engineering in polymer- and small molecule-based organic solar cells. High-performance devices were fabricated, and the device performance was correlated with nanoscale structures using various electrical, spectroscopic and microscopic characterization techniques, providing guidelines for high-efficiency cell design.

The second part focuses on perovskite solar cells (PSCs), an emerging photovoltaic technology with skyrocketing rise in power conversion efficiency (PCE) and currently showing comparable PCEs with those of existing thin film photovoltaic technologies such as CIGS and CdTe. Fabrication of large-area PSCs without compromising reproducibility and device PCE requires formation of dense, …

Gain Tuning Of Proportional Integral Controller Based On Multiobjective Optimization And Controller Hardware-In-Loop Microgrid Setup, Kumaraguru Prabakar

Doctoral Dissertations

Proportional integral (PI) control is a commonly used industrial controller framework. This PI controller needs to be tuned to obtain desired response from the process under control. Tuning methods available in literature by and large need sophisticated mathematical modelling, and simplifications in the plant model to perform gain tuning. The process of obtaining approximate plant model conceivably become time consuming and produce less accurate results. This is due to the simplifications desired by the power system applications especially when power electronics based inverters are used in it. Optimal gain selection for PI controllers becomes crucial for microgrid application. Because of …

Neuron Clustering For Mitigating Catastrophic Forgetting In Supervised And Reinforcement Learning, Benjamin Frederick Goodrich

Doctoral Dissertations

Neural networks have had many great successes in recent years, particularly with the advent of deep learning and many novel training techniques. One issue that has affected neural networks and prevented them from performing well in more realistic online environments is that of catastrophic forgetting. Catastrophic forgetting affects supervised learning systems when input samples are temporally correlated or are non-stationary. However, most real-world problems are non-stationary in nature, resulting in prolonged periods of time separating inputs drawn from different regions of the input space.

Reinforcement learning represents a worst-case scenario when it comes to precipitating catastrophic forgetting in neural networks. …

Arithmetic Logic Unit Architectures With Dynamically Defined Precision, Getao Liang

Doctoral Dissertations

Modern central processing units (CPUs) employ arithmetic logic units (ALUs) that support statically defined precisions, often adhering to industry standards. Although CPU manufacturers highly optimize their ALUs, industry standard precisions embody accuracy and performance compromises for general purpose deployment. Hence, optimizing ALU precision holds great potential for improving speed and energy efficiency. Previous research on multiple precision ALUs focused on predefined, static precisions. Little previous work addressed ALU architectures with customized, dynamically defined precision. This dissertation presents approaches for developing dynamic precision ALU architectures for both fixed-point and floating-point to enable better performance, energy efficiency, and numeric accuracy. These new …

Exploiting Cross Domain Relationships For Target Recognition, Wei Wang

Doctoral Dissertations

Cross domain recognition extracts knowledge from one domain to recognize samples from another domain of interest. The key to solving problems under this umbrella is to find out the latent connections between different domains. In this dissertation, three different cross domain recognition problems are studied by exploiting the relationships between different domains explicitly according to the specific real problems.

First, the problem of cross view action recognition is studied. The same action might seem quite different when observed from different viewpoints. Thus, how to use the training samples from a given camera view and perform recognition in another new view …

A Hardware Based Audio Event Detection System, Jacob Daniel Tobin

Masters Theses

Audio event detection and analysis is an important tool in many fields, from entertainment to security. Recognition technologies are used daily for parsing voice commands, tagging songs, and real time detection of crimes or other undesirable events. The system described in this work is a hardware based application of an audio detection system, implemented on an FPGA. It allows for the detection and characterization of gunshots and other events, such as breaking glass, by comparing a recorded audio sample to 20+ stored fingerprints in real time. Additionally, it has the ability to record flagged events and supports integration with mesh …

Implementation Of A Neuromorphic Development Platform With Danna, Jason Yen-Shen Chan

Masters Theses

Neuromorphic computing is the use of artificial neural networks to solve complex problems. The specialized computing field has been growing in interest during the past few years. Specialized hardware that function as neural networks can be utilized to solve specific problems unsuited for traditional computing architectures such as pattern classification and image recognition. However, these hardware platforms have neural network structures that are static, being limited to only perform a specific application, and cannot be used for other tasks. In this paper, the feasibility of a development platform utilizing a dynamic artificial neural network for researchers is discussed.

Dividing And Conquering Meshes Within The Nist Fire Dynamics Simulator (Fds) On Multicore Computing Systems, Donald Charles Collins

Masters Theses

The National Institute for Standards and Technology (NIST) Fire Dynamics Simulator (FDS) provides a computational fluid dynamics model of a fire, which can be visualized by using NIST Smokeview (SMV). Users must create a configuration file (*.fds) that describes the environment and other characteristics of the fire scene so that the FDS software can produce the output file (*.smv) needed for visualization.The processing can be computationally intensive, often taking between several minutes and several hours to complete. In many cases, a user will create a file that is not optimized for a multicore computing system. By dividing meshes within the …

Accuracy And Reliability Improvement Of Wide-Area Power Grid Monitoring, Lingwei Zhan

Doctoral Dissertations

Phasor Measurement Unit (PMU) is one of the key elements of wide area measurement systems (WAMS) in advanced power system monitoring, protection, and control applications. Frequency Disturbance Recorder (FDR) developed by the Power IT Laboratory at the University of Tennessee, is a low-cost and single-phase PMU used at the distribution level.

Traditional PMUs use GPS as the only timing source. They will stop working when GPS signal is lost or unstable. Two alternative GPS independent timing sources including eLoran and Chip Scale Atomic Clock were tested for long-term reliability and short-term accuracy to study the application of the two methods …

A 3rd Generation Frequency Disturbance Recorder: A Secure, Low Cost Synchophasor Measurement Device, Jerel Alan Culliss

Doctoral Dissertations

The Frequency Monitoring Network (FNET) is a wide-area phasor measurement system developed in 2003. It collects power system data using embedded devices known as Frequency Disturbance Recorders (FDRs) which are installed at distribution level voltages. These devices are single-phase synchrophasor measurement units which share a number of common attributes with their commercial counterparts.

Phasor measurements from FDRs across North America and other power grids around the world are transmitted over the Internet back to the FNET servers at the University of Tennessee. By analyzing the fluctuations in the grid’s frequency, FNET can identify disruptive events relating to the operation of …

Versatile Three-Phase Power Electronics Converter Based Real-Time Load Emulators, Jing Wang

Doctoral Dissertations

This dissertation includes the methodology, implementation, validation, as well as real-time modeling of a load emulator for a reconfigurable grid emulation platform of hardware test-bed (HTB). This test-bed was proposed by Center of Ultra-wide-area Resilient Electric Energy Transmission Network (CURENT) at the University of Tennessee, at Knoxville in 2011, to address the transmission level system challenges posed by contemporary fast changing energy technologies.

Detailed HTB introduction, including design concept, fundamental units and hardware construction, is elaborated. In the development, current controlled three-phase power electronics converter based emulator unit is adopted to create desired power system loading conditions.

In the application, …

Characterization And Realization Of High Switching-Speed Capability Of Sic Power Devices In Voltage Source Converter, Zheyu Zhang

Doctoral Dissertations

The emerging wide band-gap, silicon carbide (SiC) power devices greatly improve the switching performance due to their inherent fast switching capability. However, the high switching-speed performance makes their switching behavior become more susceptible to parasitics of the application circuit. In the end, unlike the excellent switching performance of SiC devices tested in manufacturer’ datasheets, the observed switching performance in actual power converters is almost always worse. This dissertation aims at characterization and realization of high switching-speed capability of SiC devices in one of the most widely used converter types, the voltage source converter (VSC).

To evaluate the fast dynamic characteristics …

Data Security And Privacy In Smart Grid, Yue Tong

Doctoral Dissertations

This dissertation explores novel data security and privacy problems in the emerging smart grid.

The need for data security and privacy spans the whole life cycle of the data in the smart grid, across the phases of data acquisition, local processing and archiving, collaborative processing, and finally sharing and archiving. The first two phases happen in the private domains of an individual utility company, where data are collected from the power system and processed at the local facilities. When data are being acquired and processed in the private domain, data security is the most critical concern. The key question is …

A Low-Power Bfsk/Ook Transmitter For Wireless Sensors, Mohammed Shahriar Jahan

Doctoral Dissertations

In recent years, significant improvements in semiconductor technology have allowed consistent development of wireless chipsets in terms of functionality and form factor. This has opened up a broad range of applications for implantable wireless sensors and telemetry devices in multiple categories, such as military, industrial, and medical uses. The nature of these applications often requires the wireless sensors to be low-weight and energy-efficient to achieve long battery life. Among the various functions of these sensors, the communication block, used to transmit the gathered data, is typically the most power-hungry block. In typical wireless sensor networks, transmission range is below 10 …

Alternating Current Electrokinetics Based Capacitive Affinity Biosensor: A Point-Of-Care Diagnostic Platform, Haochen Cui

Doctoral Dissertations

Capacitive bioaffinity detection using microelectrodes is considered as a promising label-free method for point-of-care diagnosis, though with challenges in sensitivity, specificity and the time “from sample to result.” This work presents an alternating current (AC)-electrokinetic based capacitive affinity sensing method that is capable of realizing rapid in-situ detection of specific biomolecular interactions such as probe-analyte binding. The capacitive biosensor presented here employs elevated AC potentials at a fixed frequency for impedimetric interrogation of the microelectrodes. Such an AC signal is capable of inducing dielectrophoresis (DEP) and AC electrothermal (ACET) effects, so as to realize in-situ enrichment of macro and even …

A Ghz-Range, High-Resolution Multi-Modulus Prescaler For Extreme Environment Applications, Benjamin Matthew Mccue

Doctoral Dissertations

The generation of a precise, low-noise, reliable clock source is critical to developing mixed-signal and digital electronic systems. The applications of such a clock source are greatly expanded if the clock source can be configured to output different clock frequencies. The phase-locked loop (PLL) is a well-documented architecture for realizing this configurable clock source. Principle to the configurability of a PLL is a multi-modulus divider. The resolution of this divider (or prescaler) dictates the resolution of the configurable PLL output frequency. In integrated PLL designs, such a multi-modulus prescaler is usually sourced from a GHz-range voltage-controlled oscillator. Therefore, a fully-integrated …

Driving And Protection Of High Density High Temperature Power Module For Electric Vehicle Application, Zhiqiang Wang

Doctoral Dissertations

There has been an increasing trend for the commercialization of electric vehicles (EVs) to reduce greenhouse gas emissions and dependence on petroleum. However, a key technical barrier to their wide application is the development of high power density electric drive systems due to limited space within EVs. High temperature environment inherent in EVs further introduces a new level of complexity. Under high power density and high temperature operation, system reliability and safety also become important.

This dissertation deals with the development of advanced driving and protection technologies for high temperature high density power module capable of operating under the harsh …

A Magnetic Actuated Fully Insertable Robotic Camera System For Single Incision Laparoscopic Surgery, Xiaolong Liu

Doctoral Dissertations

Minimally Invasive Surgery (MIS) is a common surgical procedure which makes tiny incisions in the patients anatomy, inserting surgical instruments and using laparoscopic cameras to guide the procedure. Compared with traditional open surgery, MIS allows surgeons to perform complex surgeries with reduced trauma to the muscles and soft tissues, less intraoperative hemorrhaging and postoperative pain, and faster recovery time. Surgeons rely heavily on laparoscopic cameras for hand-eye coordination and control during a procedure. However, the use of a standard laparoscopic camera, achieved by pushing long sticks into a dedicated small opening, involves multiple incisions for the surgical instruments. Recently, single …

Isolated Wired And Wireless Battery Charger With Integrated Boost Converter For Phev And Ev Applications, Madhu Sudhan Chinthavali

Doctoral Dissertations

Vehicle charging and vehicle traction drive components can be integrated for multi-functional operations, as these functions are currently operating independently. While the vehicle is parked, the hardware that is available from the traction drive can be used for charging. The only exception to this would be the dynamic vehicle-charging concept on roadways. WPT can be viewed as a revolutionary step in PEV charging because it fits the paradigm of vehicle to infrastructure (V2I) wirelessly. WPT charging is convenient and flexible not only because it has no cables and connectors that are necessary, but due more to the fact that charging …

Cmos Current-Frequency Signal Processing Unit For Bioimplantable Sensors, Madeline Nicole Threatt

Masters Theses

Over the past few decades, implantable monitoring of glucose, lactate acid, and pH monitoring has become a viable replacement for stationary monitoring. Implantable biosensing requires biosensors in conjunction with corresponding potentiostats and a signal processing unit to translate the data information to a more versatile, transmittable form. This thesis presents a current-mode signal processing unit (SPU) that merges the simplicity of a charging capacitor in feedback topology with the accuracy of a delta-sigma modulator to create a pulse train with a frequency proportional to the input current. The SPU was realized in a 0.18 µ[micro]m bulk CMOS process.

Compressed Sensing In Resource-Constrained Environments: From Sensing Mechanism Design To Recovery Algorithms, Shuangjiang Li

Doctoral Dissertations

Compressed Sensing (CS) is an emerging field based on the revelation that a small collection of linear projections of a sparse signal contains enough information for reconstruction. It is promising that CS can be utilized in environments where the signal acquisition process is extremely difficult or costly, e.g., a resource-constrained environment like the smartphone platform, or a band-limited environment like visual sensor network (VSNs). There are several challenges to perform sensing due to the characteristic of these platforms, including, for example, needing active user involvement, computational and storage limitations and lower transmission capabilities. This dissertation focuses on the study of …

Danna A Neuromorphic Computing Vlsi Chip, Christopher Paul Daffron

Masters Theses

Dynamic Adaptive Neural Network Arrays (DANNAs) are neuromorphic systems that exhibit spiking behaviors and can be designed using evolutionary optimization. Array elements are rapidly reconfigurable and can function as either neurons or synapses with programmable interconnections and parameters. Currently, DANNAs are implemented using a Field Programmable Gate Array (FPGA) and are constrained by this technology. To alleviate these constraints and introduce new and improved features, a semi-custom Very Large Scale Integration (VLSI) implementation has been created. This implementation improves upon the FPGA implementation in three key areas. The density of the array is improved, with 5,625 elements on a single …

A Low-Power, Laser-Based Delta-Sigma Modulator For The Measurement Of Atmospheric Gas Composition, Christopher Edward Crowder

Masters Theses

With the increased attention on monitoring the atmosphere’s gas composition, new ways of accurately measuring these concentrations are needed. Along with the needed increase in measurement accuracy; size, space, and power reduction is also essential in modern systems. As semiconductor technology has advanced, the abilities to meet the previously mentioned criteria are becoming more realizable.

Instrumentation used to measure the atmosphere’s composition is traditionally large, taking up much needed space and using larger amounts of power. While the larger instrumentation provides the necessary accuracy, the other constraints are sacrificed. For this reason, a smaller, yet highly accurate solution is needed. …