Power and Energy Commons^™

Linear Quadratic Optimal Control For A Cascaded Converters-Based Microgrid, Amlam Niragire

Graduate Theses and Dissertations

There is a constant transformation of the electric grid due to an ongoing interest in the deployment of renewable energy resources and electric microgrid formation. This transformation, though advantageous in many ways, poses great challenges for the energy industry and there must be a constant improvement in modeling, simulation, analysis and control techniques in order to characterize and optimize the system design and operation. In this light, the scope of this thesis is focused on developing a linear model, analyzing the stability and designing an optimal linear quadratic regulator (LQR) for a microgrid system. The microgrid system used is inspired …

Applications Of Krylov Subspace And Balanced Truncation Model Order Reduction In Power Systems, Sebastian Emanuel Garrido

Graduate Theses and Dissertations

Dynamic representations of power systems usually result in the order of hundreds or even thousands of buses. Therefore, reduction of these dynamic representations is convenient. Two applications of model order reduction in power systems are discussed in this thesis. First, Krylov subspace-based method is applied to the IEEE-123 Node Test Feeder in the context of distribution-level power systems simulation. Second, a Balanced Truncation-based model reduction is implemented in the 3-Machine 9-Bus system for designing a power system controller in the context of generation- and transmission-level power systems.

First, for the IEEE-123 Node Test Feeder, a two-sided Arnoldi algorithm is proposed …

Optimal Sensing And Transmission In Energy Harvesting Sensor Networks, Xianwen Wu

Graduate Theses and Dissertations

Sensor networks equipped with energy harvesting (EH) devices have attracted great attentions recently. Compared with conventional sensor networks powered by batteries, the energy harvesting abilities of the sensor nodes make sustainable and environment-friendly sensor networks possible. However, the random, scarce and non-uniform energy supply features also necessitate a completely different approach to energy management.

A typical EH wireless sensor node consists of an EH module that converts ambient energy to electrical energy, which is stored in a rechargeable battery, and will be used to power the sensing and transmission operations of the sensor. Therefore, both sensing and transmission are subject …

High Step-Up/Down Transformerless Multilevel Converter For Renewable Energy Applications, Haider Ghazi Mhiesan

Graduate Theses and Dissertations

This thesis focuses on a high step-up/down transformerless dc-dc modular multilevel converter (MMC) that would be applicable to dc power systems. The design achieves high voltage ratios for interfacing renewable energy sources such as photovoltaic and line interactive Uninterruptible Power System (UPS) systems. The circuit topology provides for high step-up/down dc-dc conversion ratios using an MMC approach operating in resonant mode in order to improve overall efficiency. This topology operates to step-up the input voltage with 1:10 or larger conversion ratio. As a bidirectional converter, it also provides step-down capability at the same voltage ratio (10:1 or greater). The MMC …

Control Design Of A Single-Phase Dc/Ac Inverter For Pv Applications, Haoyan Liu

Graduate Theses and Dissertations

This thesis presents controller designs of a 2 kVA single-phase inverter for photovoltaic (PV) applications. The demand for better controller designs is constantly rising as the renewable energy market continues to rapidly grow. Some background research has been done on solar energy, PV inverter configurations, inverter control design, and hardware component selection. Controllers are designed both for stand-alone and grid-connected modes of operation. For stand-alone inverter control, the outer control loop regulates the filter capacitor voltage. Combining the synchronous frame outer control loop with the capacitor current feedback inner control loop, the system can achieve both zero steady-state error and …

Mixed Mesh/Nodal Magnetic Equivalent Circuit Modeling Of A Six-Phase Claw-Pole Automotive Alternator, Daniel C. Horvath

Open Access Theses

Magnetic equivalent circuits (MECs) have been employed by many researchers to model the relationship between magnetic flux and current in electromagnetic systems such as electric machines, transformers and inductors [1] ,[2]. Magnetic circuits are analogous to electric circuits where voltage, current, resistance and conductance are the respective counterparts of magneto-motive force (MMF), magnetic flux, reluctance and permeance. The solution of MECs can be accomplished with the plethora of techniques developed for electrical circuit analysis. Specifically, mesh analysis, based on Kirchoff’s Voltage Law (KVL), and nodal analysis, based on Kirchoffs Current Law (KCL), are two very common solution techniques. Once an …

Capacity Optimization Of Battery-Generator Hybrid Power System: Toward Minimizing Maintenance Cost In Expeditionary Basecamp/Operational Energy Applications, Jude C. Onwuanumkpe

Open Access Theses

Low and transient load condition are known to have deleterious impact on the efficiency and health of diesel generators (DGs). Extensive operation under such loads reduces fuel consumption and energy conversion efficiency, and contribute to diesel engine degradation, damage, or catastrophic failure. Non-ideal loads are prevalent in expeditionary base camps that support contingency operations in austere environments or remote locations where grid electricity is either non-existent or inaccessible. The impact of such loads on DGs exacerbates already overburdened basecamp energy logistics requirements. There is a need, therefore, to eliminate or prevent the occurrence of non-ideal loads. Although advances in diesel …

Swat Model Simulation Of Bioenergy Crop Impacts On Water Quality In Cache River Watershed, Eeshan Kumar

Graduate Theses and Dissertations

Energy security through increased biofuel production is one of the components of the Energy Independence and Security Act (EISA) 2007. As per EISA 2007 mandate, appropriate independent research institutes are required to assess concerns to natural biodiversity due to biofuel production and report it to the Congress through the Environment Protection Agency (EPA). Planners, researchers, and agencies concerned with environmental regulations, ideally, would like to have location-specific information about the impacts for developing appropriate management interventions. This study examines long-term impacts on water quality in response to targeted (i.e. marginal lands) production of biofuel crops by setting up two SWAT …

Model Development And Validation For Wind Generation Transmission Systems, Mahmood Shihadeh Saadeh

Graduate Theses and Dissertations

In this research a new benchmark system is proposed for wind energy transmission systems. New model development, validation, and calibration methods for power transmission systems are proposed and implemented as well. First, a model reduction criteria is chosen based on electrical interconnection and geographical information. Model development is then done using reduction techniques on an operation model provided by a transmission operator based on the chosen criteria. Then model validation is performed using actual PMU synchrophasor measurements provided by a utility company. The model development and validation process ensures the accuracy of the developed model and makes for a realistic …

High-Frequency Transformer Design For Solid-State Transformers In Electric Power Distribution Systems, Roderick Javier Garcia Montoya

Graduate Theses and Dissertations

The objective of this thesis is to present a high- or medium-frequency transformer design methodology for Solid-State Transformer (SST) applications. SSTs have been proposed as a replacement of the traditional 50/60 Hz transformer in applications demanding high-power density. Moreover, due to the high penetration of distributed generation, DC grids, energy storage systems, and sensitive loads, SSTs have been considered as an enabling technology for envisioned future energy systems. These applications demand additional functionalities that may not be achieved with traditional transformers. For example, active power flow control, harmonic suppression, voltage regulation, voltage sag compensation, and reduced size and volume.

In …

Broadband High Efficiency Fractal-Like And Diverse Geometry Silicon Nanowire Arrays For Photovoltaic Applications, Omar Hassan Al-Zoubi

Graduate Theses and Dissertations

Solar energy has many advantages over conventional sources of energy. It is abundant, clean and sustainable. One way to convert solar energy directly into electrical energy is by using the photovoltaic solar cells (PVSC). Despite PVSC are becoming economically competitive, they still have high cost and low light to electricity conversion efficiency. Therefore, increasing the efficiency and reducing the cost are key elements for producing economically more competitive PVSC that would have significant impact on energy market and saving environment. A significant percentage of the PVSC cost is due to the materials cost. For that, thin films PVSC have been …

Top-Down Aluminum Induced Crystallization For Photovoltaics, Seth Daniel Shumate

Graduate Theses and Dissertations

Passivating silicon solar cell surfaces is critical to fabricating very high efficiency and low cost photovoltaic devices. The sun-facing surface of the solar cell, known as the emitter, is particularly important when designing a solar cell. This work focused first on an alternative method of forming the emitter of silicon solar cells, and secondly on a method for improving the surface passivation of both these non-traditional and standard n-type solar cells.

Top-down aluminum induced crystallization (TAIC) was used for forming a polycrystalline silicon layer from amorphous silicon using aluminum to catalyze the crystallization at much lower temperatures than otherwise possible. …

Experimental Verification And Integration Of A Next Generation Smart Power Management System, Tavis Clemmer

Graduate Theses and Dissertations

With the increase in energy demand by the residential community in this country and the diminishing fossil fuel resources being used for electric energy production there is a need for a system to efficiently manage power within a residence. The Smart Green Power Node (SGPN) is a next generation energy management system that automates on-site energy production, storage, consumption, and grid usage to yield the most savings for both the utility and the consumer. Such a system automatically manages on-site distributed generation sources such as a PhotoVoltaic (PV) input and battery storage to curtail grid energy usage when the price …

Design, Fabrication And Characterization Of Plasmonic Fishnet Structures For The Enhancement Of Absorption In Thin Film Solar Cells, Sayan Seal

Graduate Theses and Dissertations

Incorporating plasmonic structures into the back spacer layer of thin film solar cells (TFSCs) is an efficient way to improve their performance. The fishnet structure; which is a tunable, plasmonic light scatterer is used to enhance light absorption. Unlike other plasmonic particles that have been previously suggested, the fishnet is an electrically connected wire mesh and does not result in electric field localization, hence it results in greater absorption in the intrinsic Si layer. Unlike other designs, the fishnet structure is placed in the back spacer layer of the TFSC, so it does not block any incident light. There is …

Electrical Design Considerations And Packaging Of Power Electronic Modules, Shijie Wang

Graduate Theses and Dissertations

A modern power electronic module can save significant energy usage in the power electronic systems by improving their switching efficiencies. One way to improve the efficiency of the power electronic module is to reduce its parasitic circuit elements. The purpose of this thesis is to investigate the mitigation of parasitic circuit elements in power electronic modules. General methods of mitigating parasitic inductances were analyzed by the Q3D Extractor and verified by the time-domain reflectometry (TDR) measurements. In most cases, the TDR measurement results closely matched those predicted by the Q3D Extractor. These methods were applied to design and analyze a …

Design, Layout, And Testing Of A Silicon Carbide-Based Under Voltage Lock-Out Circuit, Michael Dalan Glover

Graduate Theses and Dissertations

Silicon carbide-based power devices play an increasingly important role in modern power conversion systems. Finding a means to reduce the size and complexity of these systems by even incremental amounts can have a significant impact on cost and reliability. One approach to achieving this goal is the die-level integration of gate driver circuitry with the SiC power devices. Aside from cost reductions, there are significant advantages to the integration of the gate driver circuits with the power devices. By integrating the gate driver circuitry with the power devices, the parasitic inductances traditionally seen between the gate driver and the switching …

Intermediate Band Solar Cells Based On Inas Quantum Dots Embedded In Ingaas Quantum Well, Ramesh Vasan

Graduate Theses and Dissertations

Intermediate band solar cells based on quantum dots and quantum wells with anti-reflection coating are investigated in this thesis. The demand for high efficient solar cells as an alternate source of energy is the main motivation for this research project. Intermediate band solar cells based on quantum dots were the subject of intensive research in recent years. High power conversion efficiency was predicted from InAs/GaAs intermediate band solar cells as the presence of InAs quantum dots increased the absorption below the band gap of the host material.

In this thesis, an attempt has been made to further increase the absorption …

Synthesis Of Optimized Inp/Zns Core/Shell Nanocrystals And Tio2 Nanotubes For Quantum Dot Sensitized Solar Cells, Seungyong Lee

Graduate Theses and Dissertations

Synthesis of InP/ZnS core/shell nanocrystals and TiO₂ nanotubes and the optimization study to couple them together were explored for quantum dot sensitized solar cells. Its intrinsic nontoxicity makes the direct band gap InP/ZnS core/shell be one of the most promising semiconductor nanocrystals for optoelectric applications, with the advantage of tuning the optical absorption range in the desired solar spectrum region. Highly luminescent and monodisperse InP/ZnS nanocrystals were synthesized in a non-coordinating solvent. By varying the synthesis scheme, different size InP/ZnS nanocrystals with emission peaks ranging from 520 nm to 620 nm were grown. For the purpose of ensuring air …

Performance And Cost Analysis Of A Structured Concrete Thermocline Thermal Energy Storage System, Matt Nicholas Strasser

Graduate Theses and Dissertations

Increasing global energy demands and diminishing fossil fuel resources have raised increased interest in harvesting renewable energy resources. Solar energy is a promising candidate, as sufficient irradiance is incident to the Earth to supply the energy demands of all of its inhabitants. At the utility scale, concentrating solar power (CSP) plants provide the most cost-efficient method of harnessing solar energy for conversion to electrical energy. A major roadblock to the large-scale implementation of CSP plants is the lack of thermal energy storage (TES) that would allow the continued production of electricity during the absence of constant irradiance. Sensible heat TES …

Thermal And Electrical Parasitic Modeling For Multi-Chip Power Module Layout Synthesis, Zihao Gong

Graduate Theses and Dissertations

This thesis presents thermal and electrical parasitic modeling approaches for layout synthesis of Multi-Chip Power Modules (MCPMs). MCPMs integrate power semiconductor devices and drive electronics into a single package. As the switching frequency of power devices increases, the size of the passive components are greatly reduced leading to gains in efficiency and cost reduction. In order to increase switching frequency, electrical parasitics in MCPMs need to be reduced through tighter electronic integrations and smaller packages. As package size is decreased, temperature increases due to less heat dissipation capability. Thus, it is crucial to consider both thermal and electrical parasitics in …

Energy-Based Analysis Of Utility Scale Hybrid Power Systems, Kwame Agyenim-Boateng

UNLV Theses, Dissertations, Professional Papers, and Capstones

The promise of large-scale use of renewables such as wind and solar for supplying electrical power is tempered by the sources' transient behavior and the impact this would have on the operation of the grid. Among the methods cited for addressing some of those concerns are exploring the complementary nature of solar and wind power generation, and through the use of supplemental energy storage. While the technology for the latter has not been proven to be economical on a large scale at the present time, some assessments of what magnitude is required can be made. An energy-based analysis of utility …

Fabrication Of Composite Nanomaterials For Thin Film Amorphous Silicon Solar Cells, Benjamin Seth Newton

Graduate Theses and Dissertations

A material with the precise combination of amorphous silicon and polycrystalline silicon would be able to take advantage of the high absorption capabilities of amorphous silicon and the electron transport capabilities of polycrystalline silicon. Polycrystalline nanostructures in the form of wires can also take advantage of other properties of light absorption, trapping and scattering inherent in nanowire structures. These properties of high absorption and electron transport in one device would lead to advances in the search for highly efficient low cost solar cells and sensors. In this work a thin film material composed of an array of polycrystalline silicon nanostructures …

Investments In Energy Technological Change Under Uncertainty, Ekundayo Shittu

Doctoral Dissertations 1896 - February 2014

This dissertation addresses the crucial problem of how environmental policy uncertainty influences investments in energy technological change. The rising level of carbon emissions due to increasing global energy consumption calls for policy shift. In order to stem the negative consequences on the climate, policymakers are concerned with carving an optimal regulation that will encourage technology investments. However, decision makers are facing uncertainties surrounding future environmental policy. The first part considers the treatment of technological change in theoretical models.

This part has two purposes: (1) to show-through illustrative examples-that technological change can lead to quite different, and surprising, impacts on the …