Power and Energy Commons^™

Out-Of-Step Detection Based On Zubov’S Approximation Boundary Method, Yawei Wei

Dissertations, Master's Theses and Master's Reports - Open

Disturbances in power systems may lead to electromagnetic transient oscillations due to mismatch of mechanical input power and electrical output power. Out-of-step conditions in power system are common after the disturbances where the continuous oscillations do not damp out and the system becomes unstable. Existing out-of-step detection methods are system specific as extensive off-line studies are required for setting of relays. Most of the existing algorithms also require network reduction techniques to apply in multi-machine power systems. To overcome these issues, this research applies Phasor Measurement Unit (PMU) data and Zubov’s approximation stability boundary method, which is a modification of …

Fault Location Algorithms, Observability And Optimality For Power Distribution Systems, Wanjing Xiu

Theses and Dissertations--Electrical and Computer Engineering

Power outages usually lead to customer complaints and revenue losses. Consequently, fast and accurate fault location on electric lines is needed so that repair work can be carried out as fast as possible.

Chapter 2 describes novel fault location algorithms for radial and non-radial ungrounded power distribution systems. For both types of systems, fault location approaches using line to neutral or line to line measurements are presented. It’s assumed that network structure and parameters are known, so that during-fault bus impedance matrix of the system can be derived. Functions of bus impedance matrix and available measurements at substation are formulated, …

Prediction Model To Estimate The Zero Crossing Point For Faulted Waveforms, Md. Shakawat Hossan

Theses and Dissertations--Electrical and Computer Engineering

In any power system, fault means abnormal flow of current. Insulation breakdown is the cause of fault generation. Different factors can cause the breakdown: Wires drifting together in the wind, Lightning ionizing air, wires with contacts of animals and plants, Salt spray or pollution on insulators. The common type of faults on a three phase system are single line-to-ground (SLG), Line-to-line faults (LL), double line-to-ground (DLG) faults, and balanced three phase faults. And these faults can be symmetrical (balanced) or Unsymmetrical (imbalanced).In this Study, a technique to predict the zero crossing point has been discussed and simulated. Zero crossing point …

Testing Of Two Novel Semi-Implicit Particle-In-Cell Techniques, Trenton J. Godar

Browse all Theses and Dissertations

PIC (Particle-in-cell) modeling is a computational technique which functions by advancing computer particles through a spatial grid consisting of cells, on which can be placed electric and magnetic fields. This method has proven useful for simulating a wide range of plasmas and excels at yielding accurate and detailed results such as particle number densities, particle energies, particle currents, and electric potentials. However, the detailed results of a PIC simulation come at a substantial cost of computational requirement and the algorithm can be susceptible to numerical instabilities. As processors become faster and contain more cores, the computational expense of PIC simulations …

Modeling And Validation Of A Synchronous-Machine/Controlled-Rectifier System, Kyle A. Hord

Theses and Dissertations--Electrical and Computer Engineering

The hardware validation of a novel average-value model (AVM) for the simulation of a synchronous-generator/controlled rectifier system is presented herein. The generator is characterized using genetic algorithm techniques to fit standstill frequency response (SSFR) measurements to q and d-axis equivalent circuits representing the generator in the rotor reference frame. The generator parameters form the basis of a detailed model of the system, from which algebraic functions defining the parametric AVM are derived. The average-value model is compared to the physical system for a variety of loading and operating conditions including step load change, change in delay angle, and external closed-loop …

Investigation Of Protection Issues And Method For The Distribution System With Distributed Generations, Ke Xu

Theses and Dissertations--Electrical and Computer Engineering

Because DGs are introduced into distribution systems, the coordination of fuses and reclosers doesn’t work well. It means the original protection schemes are not available for the distribution systems with DGs. This thesis paper presents the study on the impacts of DGs on the fault current and voltage in the distribution system by the simulation of a model distribution system. After we study the impacts of DG on distribution systems, there is an introduction of current several current protection schemes and fault locations methods. At last, an adaptive protection scheme with a more efficient fault location method for the distribution …

Multifrequency Averaging In Power Electronic Systems, Fei Pan

Theses and Dissertations--Electrical and Computer Engineering

Power electronic systems have been widely used in the electrical power processing for applications with power levels ranging from less than one watt in battery-operated portable devices to more than megawatts in the converters, inverters and rectifiers of the utility power systems. These systems typically involve the passive elements such as inductors, capacitors, and resistors, the switching electronic components such as IGBTs, MOSFETS, and diodes, and other electronic circuits. Multifrequency averaging is one of the widely used modeling and simulation techniques today for the analysis and design of power electronic systems. This technique is capable of providing the average behavior …

A New Design Of Dc-Dc Converter For Capacitive Deionization Process, Zhiao Li

Theses and Dissertations--Electrical and Computer Engineering

The shortage of clean water has become a significant global problem, and capacitive deionization (CDI) is a technology that can be used to help relieve the problem. A Ćuk converter system that can recover energy from CDI cells is described. This converter transfers energy between two CDI cells when a cell is in its desorption period, allowing energy that would otherwise be lost to be recovered and improving overall system efficiency. In order to control the states of the MOSFET switches in the converter, a self boost charge pump is used. In this way, the microcontroller can control system duty …

Coordinated Voltage And Reactive Power Control Of Power Distribution Systems With Distributed Generation, Esa A. Paaso

Theses and Dissertations--Electrical and Computer Engineering

Distribution system voltage and VAR control (VVC) is a technique that combines conservation voltage reduction and reactive power compensation to operate a distribution system at its optimal conditions. Coordinated VVC can provide major economic benefits for distribution utilities. Incorporating distributed generation (DG) to VVC can improve the system efficiency and reliability. The first part of this dissertation introduces a direct optimization formulation for VVC with DG. The control is formulated as a mixed integer non-linear programming (MINLP) problem. The formulation is based on a three-phase power flow with accurate component models. The VVC problem is solved with a state of …

Hydrothermal Processing Of Biomass For Biofuels, Sandeep Kumar

Civil & Environmental Engineering Faculty Publications

[First paragraph] In recent years, significant research interests have been placed on the conversion of non-food biomass resources such as lignocellulosic biomass (terrestrial) and algae (aquatic) to biofuels. Among all the alternative or renewable energy options, biomass is the only resource which is carbon neutral and can potentially replace part of fossil fuels use as liquid transportation fuels as well as contribute to electricity generation. Therefore, it can play a significant role in partially replacing oil, natural gas, and coal utilization for heat and energy generation. However, high moisture content of fresh biomass or algae is one of the major …

Bermudagrass Growth In Soil Contaminated With Hydraulic Fracturing Drilling Fluid, Douglas Wolf, Kristofor R. Brye

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

Hydraulic fracturing is the process of injecting aqueous solutions at high pressure to break apart rock formations and increase the extraction of natural gas. The solutions are recovered and have been land-applied as one disposal technique. Excessive fluid application can result in increased soil salinity that can inhibit plant growth. The objective of this greenhouse study was to evaluate the effects of inorganic fertilizer, broiler litter, and Milorganite® and soil depth interval (0-15 cm or 0-30 cm) on the growth of bermudagrass [Cynodon dactylon (L.) Pers] in soil that was collected from a site that had been contaminated with fracturing …

Dilute-Acid-Extractable Phosphorus, Arsenic, And Selenium In Weathered And Fresh Coal Fly Ash, Chris Wilbanks, Kristofor Brye, David Miller

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

Fly ash is a byproduct of the combustion of coal, primarily by coal-fired power plants. Over 97.8 million tonnes of fly ash are produced each year in the United States. Fly ash can contain trace elements in concentrations that can cause health risks. Recent spills have highlighted that fly ash disposal is problematic. The objective of this study was to evaluate the effects of fly-ash type (fresh and weathered) from a local coal-burning power plant and extraction time (2 and 6 h) on dilute-acid extractable concentrations of phosphorus (P), arsenic (As), and selenium (Se). Ash samples were extracted with 0.1 …

Analysis Of Onshore Wind - Solar Pv - Battery Bank Power Generation System Development For Toamasina Port, Hary Lys Jean Louis Soloniainanirinanandrianina

World Maritime University Dissertations

No abstract provided.

Cost And Benefit Analysis Of Shore Side Electricity In The Port Of Tanjung Perak, Indonesia, Oscar Yogi Yustiano

World Maritime University Dissertations

No abstract provided.

Application Of Synchrotron Radiation Based Electrochemical In-Situ Techniques To Study Of Electrode Materials For Lithium-Ion Batteries, Zheng-Liang Gong, Wei Zhang, Dong-Ping Lv, Xiao-Gang Hao, Wen Wen, Zheng Jiang, Yong Yang

Journal of Electrochemistry

Due to its merits of high brightness and high intensity, high level of polarization and wide tunability in energy, etc., synchrotron radiation technique provides an unique platform for analysis of the relationship among composition–structure–performance of materials for lithium ion batteries, especially for in-situ, real time dynamic investigation of the electrochemical reaction mechanism, aging process and failure mechanism during charge-discharge cycling. In this paper, we review the latest developments in application of synchrotron based electrochemical in-situ experimental methods to studies of lithium ion batteries. The paper mainly focuses on the application of electrochemical in-siu XRD and XAFS techniques to the investigations …

Controllable Synthesis Of Dispersed Spherical Fe3O4 Nanoparticles As Lithium-Inserted Materials, Hong-Li Zou, Wei-Shan Li

Journal of Electrochemistry

Dispersed spherical Fe₃O₄ nanoparticles were synthesized by a hydrothermal method. The influences of odecyl trimethyl ammonium bromide (DTAB) concentration on the morphology and particle size of the as-prepared Fe₃O₄ were studied. Electrochemical performance of the as-prepared sample as anode materials of lithium ion battery was investigated. It is found that the as-prepared sample exhibits superior rate performance and cycle performance. The nano-sized materials provide structural stability and favor the transfer of lithium ions.

An Investigation On The Solid Electrolyte Interphase Of Silicon Anode For Li-Ion Batteries Through Force Curve Method, Jie-Yun Zheng, Hao Zheng, Rui Wang, Hong Li, Li-Quan Chen

Journal of Electrochemistry

Non-aqueous electrolyte has been widely used in commercial Li-ion batteries. Optimized choices are proceeding among the various types of salts and solvents in an effort to achieve higher performance of electrolyte. However, the electrolyte will be reduced in low potential and the reductive product will be deposited on the surface of anode to form a passivating layer, solid electrolyte interphase (SEI). Herein an atomic force microscopy (AFM) based method was introduced to study the structure and mechanical property of SEI on silicon thin film anode during the first cycle. Silicon has been known as the most potential candidate anode for …

Preparation And Electrochemical Properties Of Flake-Like Liv3O8 By Soft Template Assisted Sol-Gel Method As Anode Material For Aqueous Li-Ion Battery, Shuai Tan, Dan Sun, Hai-Yan Wang, Tian-Li Hou, Zhong-Xing Xiao, You-Gen Tang

Journal of Electrochemistry

Composite electrode of CuF₂/MoO₃/C was fabricated through high energy mechanical milling. The properties of CuF₂/MoO₃/C were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (TEM), galvanostatic charge-discharge measurements, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results showed that the grain sizes of CuF₂ and MoO₃ after milling were 200 ~ 300 nm, and the initial discharge capacity of CuF₂/MoO₃/C was 647 mAh·g^-1 at room temperature and at a current density of 10 mAh·g^-1. However, the …

Synthesis And Electrochemical Performance Of Nano Licopo4 By Polyol Method, Fei Wang, Yang Jun

Journal of Electrochemistry

High potential LiCoPO₄ cathode material was synthesized by polyol method. Carbon layer of ca. 3 nm thick was coated on the LiCoPO₄ surfaces by chemical vapor deposition from methylbenzene. Crystalline structure, morphology and electrochemical performance of the sample were studied by XRD, SEM, TEM, CV and galvanostatic charge/discharge curve. The synthesized material via polyol method showed a pure phase of LiCoPO₄. The LiCoPO₄/C electrode delivered a high discharge capacity of 132 mAh·g^-1 and maintained 78% of the initial capacity after 50 cycles at 0.1C rate. The two-step extraction/insertion behavior of Li⁺ in …

Aqueous Solution-Evaporation Route Synthesis And Phase Structural Research Of The Li-Rich Cathode Li1.23Ni0.09Co0.12Mn0.56O2 By In-Situ Xrd, Chong-Heng Shen, Shou-Yu Shen, Zhou Lin, Xiao-Mei Zheng, Hang Su, Ling Huang, Jun-Tao Li, Shi-Gang Sun

Journal of Electrochemistry

The Li-rich Li_1.23Ni_0.09Co_0.12Mn_0.56O₂ material was synthesized via aqueous solution-evaporation route. The structure and morphology of the material were characterized by means of XRD and SEM. The results indicated that the single particle of the product was polygonal with the size of 330 nm and the structure was layered solid solution with a certain amount of Li₂MnO₃. Electrochemical tests showed that the first discharge capacity of the Li-rich layered material was 250.8 mAh·g^-1 at 0.1C, the capacity retention was 86.5% after 40 cycles. Through in-situ XRD study …