Engineering Commons^™

Modeling And Control Of Power Electronics Interfaced Load For Transmission Power Network Analysis, Shuyao Wang

Doctoral Dissertations

The penetration level of power electronics (PE) interfaced loads has been gradually increasing in recent years. It is beneficial to equip the electric load with a PE interface since it allows for more advanced control of the load performance. Furthermore, the increasing penetration of PE interfaced loads will bring both challenges and opportunities to power network resilience and reliability.

However, the lack of modeling and control design for PE interfaced load units in the transmission-level power network analysis, especially for these high-penetrated high-power-rating load applications, limits the accuracy of evaluating the dynamic performance and stability status of the power network. …

Design Considerations For Gan-Based Photovoltaic Inverter And Solid-State Circuit Breaker, Zhe Yang

Doctoral Dissertations

Featuring low specific on-state resistance, high switching speed, and zero reverse recovery current, Gallium Nitride (GaN) transistor is becoming one of the most promising devices for power electronic applications. This dissertation presents some design considerations for photovoltaic (PV) inverters and solid-state circuit breakers (SSCBs) using GaN devices. Several related challenges and solutions will be discussed in this dissertation.

First, the filter design for full bridge PV inverter is discussed, which includes the design and optimization of individual inductor and overall power filter. The inductor design takes the fringing effect into account, and achieves optimal design with simple algorithm. Then, the …

Switching Performance Evaluation, Design, And Test Of A Robust 10 Kv Sic Mosfet Based Phase Leg For Modular Medium Voltage Converters, Xingxuan Huang

Doctoral Dissertations

10 kV SiC MOSFETs are one of the most promising power semiconductor devices for next-generation high-performance modular medium voltage (MV) converters. With extraordinary device characteristics, 10 kV SiC MOSFETs also bring a variety of challenges in the design and test of MV converters. To tackle these inherent challenges, this dissertation focuses on a robust half bridge (HB) phase leg based on 10 kV SiC MOSFETs for modular MV converters. A baseline design and test of the phase leg is established first as the foundation of the research in this dissertation.

Thorough evaluation of 10 kV SiC MOSFETs’ switching performance in …

Modeling And Control Of A 7-Level Switched Capacitor Rectifier For Wireless Power Transfer Systems, Spencer Cochran

Doctoral Dissertations

Wireless power continues to increase in popularity for consumer device charging. Rectifier characteristics like efficiency, compactness, impedance tunability, and harmonic content make the multi-level switched capacitor rectifier (MSC) an exceptional candidate for modern WPT systems. The MSC shares the voltage conversion characteristics of a post-rectification buck-boost topology, reduces waveform distortion via its multi-level modulation scheme, demonstrates tank tunability via the phase control inherent to actively switched rectifiers, and accomplishes all this without a bulky filter inductor. In this work, the MSC WPT system operation is explained, and a loss model is constructed. A prototype system is used to validate the …

Characterization Techniques And Cation Exchange Membrane For Non-Aqueous Redox Flow Battery, Kun Lou

Doctoral Dissertations

The motivation of this work comes from one of the major problems of emerging non-aqueous flow battery (NAFB) that a separator or membrane which facilitates conductivity and blocks redox species crossover does not exist. Although many aspects of principles can be mirrored from mature fuel cell and aqueous flow battery, it is found that some well-defined membrane properties in aqueous systems such as swelling, transport and interactions are different in non-aqueous solvents to some extent. However, the approach of this work does follow the way perfluorosulfonate ion exchange membrane (PFSA) facilitated development of fuel cell and aqueous flow battery in …

Impact And Application Of Real-Time Control On Stormwater Systems, Aaron A. Akin

Doctoral Dissertations

Stormwater control measures (SCMs) such as dry extended detention basins and wet ponds are common practices implemented by engineers and designers to mitigate the impact of stormwater runoff. These practices are designed based on historical rainfall data to attenuate runoff to pre-development conditions and, once they are installed, are unable to adapt to changing rainfall patterns or watershed restoration objectives. To solve these climate resiliency issues, several studies were conducted which investigated the impact of retrofitting such systems with a controllable outlet to increase or change detention times during rainfall events along with the novel instrumentation and methodologies necessary for …

Sensor Fusion For Object Detection And Tracking In Autonomous Vehicles, Mohamad Ramin Nabati

Doctoral Dissertations

Autonomous driving vehicles depend on their perception system to understand the environment and identify all static and dynamic obstacles surrounding the vehicle. The perception system in an autonomous vehicle uses the sensory data obtained from different sensor modalities to understand the environment and perform a variety of tasks such as object detection and object tracking. Combining the outputs of different sensors to obtain a more reliable and robust outcome is called sensor fusion. This dissertation studies the problem of sensor fusion for object detection and object tracking in autonomous driving vehicles and explores different approaches for utilizing deep neural networks …

Advanced Wide-Area Monitoring System Design, Implementation, And Application, Weikang Wang

Doctoral Dissertations

Wide-area monitoring systems (WAMSs) provide an unprecedented way to collect, store and analyze ultra-high-resolution synchrophasor measurements to improve the dynamic observability in power grids. This dissertation focuses on designing and implementing a wide-area monitoring system and a series of applications to assist grid operators with various functionalities. The contributions of this dissertation are below:

First, a synchrophasor data collection system is developed to collect, store, and forward GPS-synchronized, high-resolution, rich-type, and massive-volume synchrophasor data. a distributed data storage system is developed to store the synchrophasor data. A memory-based cache system is discussed to improve the efficiency of real-time situation awareness. …

Model-Based And Model-Free Approaches For Power System Security Assessment, Mariana Magdy Mounir Kamel

Doctoral Dissertations

Continuous security assessment of a power system is necessary to insure a reliable, stable, and continuous supply of electrical power to customers. To this end, this dissertation identifies and explores some of the various challenges encountered in the field of power system security assessment. Accordingly, several model-based and/or model-free approaches were developed to overcome these challenges.

First, a voltage stability index, named TAVSI, is proposed. This index has three important features: TAVSI applies to general load models including ZIP, exponential, and induction motor loads; TAVSI can be used for both measurement-based and model-based voltage stability assessment; and finally, TAVSI is …

Modeling, Measurement And Mitigation Of Fast Switching Issues In Voltage Source Inverters, Wen Zhang

Doctoral Dissertations

Wide-bandgap devices are enjoying wider adoption across the power electronics industry for their superior properties and the resulting opportunities for higher efficiency and power density. However, various issues arise due to the faster switching speed, including switching transient voltage overshoot, unstable oscillation, gate driving and evaluation difficulty, measurement and monitoring challenge, and potential load insulation degradation. This dissertation first sets out to model and understand the switching transient voltage overshoots. Unique oscillation patterns and features of the turn-on and turn-off overvoltage are discovered and analyzed, which provides new insights into the switching transient. During the experimental characterization, a new unstable …

Non-Contact Techniques For Human Vital Sign Detection And Gait Analysis, Farnaz Foroughian

Doctoral Dissertations

Human vital signs including respiratory rate, heart rate, oxygen saturation, blood pressure, and body temperature are important physiological parameters that are used to track and monitor human health condition. Another important biological parameter of human health is human gait. Human vital sign detection and gait investigations have been attracted many scientists and practitioners in various fields such as sport medicine, geriatric medicine, bio-mechanic and bio-medical engineering and has many biological and medical applications such as diagnosis of health issues and abnormalities, elderly care and health monitoring, athlete performance analysis, and treatment of joint problems. Thoroughly tracking and understanding the normal …

Towards Secure Deep Neural Networks For Cyber-Physical Systems, Jiangnan Li

Doctoral Dissertations

In recent years, deep neural networks (DNNs) are increasingly investigated in the literature to be employed in cyber-physical systems (CPSs). DNNs own inherent advantages in complex pattern identifying and achieve state-of-the-art performances in many important CPS applications. However, DNN-based systems usually require large datasets for model training, which introduces new data management issues. Meanwhile, research in the computer vision domain demonstrated that the DNNs are highly vulnerable to adversarial examples. Therefore, the security risks of employing DNNs in CPSs applications are of concern.

In this dissertation, we study the security of employing DNNs in CPSs from both the data domain …

Machine Learning With Topological Data Analysis, Ephraim Robert Love

Doctoral Dissertations

Topological Data Analysis (TDA) is a relatively new focus in the fields of statistics and machine learning. Methods of exploiting the geometry of data, such as clustering, have proven theoretically and empirically invaluable. TDA provides a general framework within which to study topological invariants (shapes) of data, which are more robust to noise and can recover information on higher dimensional features than immediately apparent in the data. A common tool for conducting TDA is persistence homology, which measures the significance of these invariants. Persistence homology has prominent realizations in methods of data visualization, statistics and machine learning. Extending ML with …

Grid-Forming Converter Control Method To Improve Dc-Link Stability In Inverter-Based Ac Grids, Ishita Ray

Doctoral Dissertations

As renewable energy sources with power-electronic interfaces become functionally and economically viable alternatives to bulk synchronous generators, it becomes vital to understand the behavior of these inverter-interfaced sources in ac grids devoid of any synchronous generation, i.e. inverter-based grids. In these types of grids, the inverters need to operate in parallel in grid-forming mode to regulate and synchronize their output voltage while also delivering the power required by the loads. It is common practice, therefore, to mimic the parallel operation control of the very synchronous generators that these inverter-based sources are meant to replace. This practice, however, is based on …

Wide Area Damping Control To Improve Transient Stability And Hardware-In-The-Loop (Hil) Implementation, Ibrahim Abdullah Altarjami

Doctoral Dissertations

In this dissertation, the impacts of WADCs on system transient stability are investigated, including system separation prevention under large disturbances and tie-line power transfer limit enhancement with consideration of a three-phase fault on one of the two tie-lines. The full Saudi power grid model in PSS/e is reduced for the real-time simulation on the Real-Time Digital Simulator (RTDS), and thus the developed WADCs can be tested in a controller hardware-in-the-loop environment in the future. The RTDS model is validated by comparing the full PSS/e model and the reduced PSS/e model under different contingencies. The WADCs are designed using a measurement-driven …