• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 97
  • 8
  • 3
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 430
  • 430
  • 148
  • 128
  • 117
  • 108
  • 72
  • 65
  • 60
  • 48
  • 43
  • 41
  • 41
  • 38
  • 37
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Optimum design of unanchored Salter-Cam wave energy systems

Tang, Chung-Yao. January 1982 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1982. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 134-137).
72

A Clean Electricity Future: Assessing the Role of Wide-Area Power System Operations in Supporting Weather-Driven Renewable Energy in the U.S.

Picciano, Paul D 01 January 2016 (has links)
Over the coming decades, renewable energy sources, namely wind and solar, will need to play a larger role in our nation’s energy mix as we seek to lower greenhouse emissions and respond to renewable energy policies and the EPA’s Clean Power Plan. This thesis assesses the role of wider-area power system operations in the U.S. as a powerful solution in supporting the integration of these weather-driven, variable energy resources that pose substantial challenges to grid reliability. The expansion and integration of organized electricity markets and transmission networks over wider geographic areas can (1) help reduce net-variability in wind and solar power generation while improving reliability; (2) provide an outlet for over-generation while reducing curtailment; (3) improve resource utilization while enabling resource sharing and lowering electricity costs; and (4) enable low-cost pollution reduction by providing a cheap alternative to fossil-fuel generation. Through power industry assessment, case-study analyses, and modeling research using NOAA’s National Energy with Weather System Simulator to compare scenarios of regional expansion versus a nation power system, this paper evaluates the feasibility and role of wide-area expansion and integration in achieving higher levels of variable renewable energy than our current system is capable of supporting.
73

Protective Relaying Student Laboratory

Pretzer, Kenan W 01 May 2017 (has links)
Facing a rapidly-changing power industry, the electrical engineering department at Cal Poly San Luis Obispo proposed Advanced Power Systems Initiatives to better prepare its students for entering the power industry. These initiatives call for the creation of a new laboratory curriculum that uses microprocessor-based relays to reinforce the fundamental concepts of power system protection. This paper summarizes a laboratory system fit for this task and presents a set of proposed laboratory experiments to establish a new laboratory course at Cal Poly. The experiments expose students to the capabilities of industry-standard microprocessor-based relays through hands-on procedures that demonstrate common power system protection schemes. Relays studied in this project support transformer, transmission line, and induction motor protection.
74

Smart DC Wall Outlet Design with Improved Load Voltage Detection

Granieri, Patrick Donovon 01 June 2019 (has links)
A standard home in the United States has access to the 120V AC power grid for use with home appliances. Many electronics used at home are powered by a DC power supply, which loses energy in the conversion from AC power. The DC House project avoids any conversion between AC and DC by storing energy in batteries as DC power and supplying it directly to DC appliances. While AC systems feature a standardized output voltage, no such standard exists for DC systems. The Smart DC Wall Outlet solves this by automatically adjusting its output voltage to meet any required DC load voltage. A hardware solution was developed using a microcontroller in tandem with a DC to DC Buck converter to monitor trends in the output current and set the output voltage accordingly. The Smart DC Wall Outlet features two 100W output channels that were able to correctly identify the required output voltage of five out of seven test devices. Results indicate that it is possible to generalize the turn on characteristics of DC devices, but that other solutions may find more success.
75

System Design Considerations and the Feasibility of Passively Compensated, Permanent Magnet, Iron-Core Compulsators to Power Small Railgun Platforms

Macgregor, Collin Taylor 01 August 2013 (has links) (PDF)
This thesis provides insight into the different aspects of compulsator design for use with railgun systems. Specifically, the design space is explored for passively compensated, permanent magnet iron-core compulsators. Seven design parameters are varied within a compulsator model developed for the Cal Poly Compulsator (CPCPA). The Matlab code for this model is included within the appendix. Efforts were made to compare and validate this compulsator model to published data from existing systems. The compulsator model was found to match closely with discharge pulse length, but resulted in lower values for peak current and projectile velocity by 50% and 30% respectively when compared to published data.
76

Analysis and Design of Continuous Input Current Multiphase Interleaved Buck Converter

Zich, Sean Michael 01 January 2009 (has links) (PDF)
The power requirements for microprocessors have been increasing per Moore's Law. According to International Technology Roadmap (ITRS), Voltage Regulator Module (VRM) for microprocessors will be about 200 W at 1 V output in 2010. With the VRM’s topology of synchronous buck, serious technical challenges such as small duty cycle, high switching frequencies, and higher current demands, contribute to decreased power density and increased cost. This thesis proposes a Continuous Input Current Multiphase Interleaved Buck topology to solve the technical challenges of powering future microprocessors. This new topology is aimed to improve past topologies by providing continuous input current and improved efficiency. An open loop system of the proposed new topology is simulated using OrCAD PSpice to evaluate the performance criteria of the VRM. A hardware prototype of a four-phase Continuous Input Current Multiphase Interleaved Buck Converter is constructed and tested to assess the targeted improvements.
77

SINGLE PHASE MULTILEVEL INVERTER FOR GRID-TIED PHOTOVOLTAIC SYSTEMS

Prichard, Martin Edward 01 January 2015 (has links)
Multilevel inverters offer many well-known advantages for use in high-voltage and high-power applications, but they are also well suited for low-power applications. A single phase inverter is developed in this paper to deliver power from a residential-scale system of Photovoltaic panels to the utility grid. The single-stage inverter implements a novel control technique for the reversing voltage topology to produce a stepped output waveform. This approach increases the granularity of control over the PV systems, modularizing key components of the inverter and allowing the inverter to extract the maximum power from the systems. The adaptive controller minimizes harmonic distortion in its output and controls the level of reactive power injected to the grid. A computer model of the controller is designed and tested in the MATLAB program Simulink to assess the performance of the controller. To validate the results, the performance of the proposed inverter is compared to that of a comparable voltage-sourced inverter.
78

Optimization and Control of an Energy Management System for Microgrids

Yu, Xiang 04 1900 (has links)
<p>An increasing concern over environmental impacts of fossil fuels and sustainability of energy resources is leading to significant changes in the electric power systems. Decentralized power generation, in particular, is emerging as one of the most effective and promising tools in addressing these concerns.</p> <p>Microgrids are small-scale electricity grids with elements of load, generation and storage. Microgrids have emerged as an essential building block of a future smart grid, and an enabling technology for distributed power generation and control. This thesis presents an optimization-based approach for the design and control of energy management systems (EMS) for electric microgrids. A linear programming formulation of power/energy management is proposed to minimize energy cost for a microgrid with energy storage and renewable energy generation, by taking advantage of time-of-use (TOU) pricing. The thesis also addresses the issue of sizing of the battery storage and solar power generation capacity by formulating and solving a mixed integer linear programming (MILP) problem. The aim of the optimization is to minimize the combined capital and electricity usage cost subject to applicable physical constraints. Several case scenarios are analyzed for grid-connected microgrids in residential, commercial and industrial settings, as well as a case of an islanded microgrid intended for a remote community.</p> <p>Finally, the thesis investigates circuit level control of a microgrid with EMS. A finite state machine based control logic is proposed that enables outage ride through and smooth transition between islanded and grid connected operation. Simulation results are provided to demonstrate the effectiveness of the proposed controller under various possible scenarios.</p> / Master of Applied Science (MASc)
79

Double-Rotor Switched Reluctance Machine for Integrated Electro-Mechanical Transmission in Hybrid Electric Vehicles

Yang, Yinye 03 March 2015 (has links)
<p>The world transportation sector has been relying on the oil industry for more than a hundred years, accounting for the largest oil consumption and one third of the greenhouse gas emissions. However, with the boosting demand, escalating national energy security concerns and emerging environmental issues, reducing and displacing petroleum fuel in transportation sector has become an urging global target. As a result, hybrid electric vehicles evolve as one solution to displace petroleum fuel by utilizing vehicle onboard electrical systems, achieving higher fuel economy and less emissions by vehicle electrification and hybridization.</p> <p>However, since hybrid electric vehicles add additional electrical components and systems to realize better fuel economy, the system complexity increases and thus the cost increases. Hence, it is an objective of this thesis research to focus on the integrations and optimizations, aiming to simplify and optimize the hybrid power-trains in both system level and component level.</p> <p>This thesis contributes to a novel integrated electro-mechanical hybrid transmission that is potentially more compact and more operational flexible with fewer components compared to the GM Allison Two-Mode hybrid transmission. Comprehensive commercialized power-train transmissions are reviewed and analyzed to serve as background information for comparison. It also contributes to a family of double-rotor switched reluctance machines that are more integrated and suitable for hybrid electric vehicle applications. A prototype double-rotor switched reluctance machine has been built and tested for concept proving. Detailed machine design process is reported with the emphasis on design novelties. Finite element analysis and optimization techniques are applied and the accuracy is confirmed by the experiments. In addition, methods of machine loss analysis, thermal analysis and drive analysis are established; manufacturing and testing procedures are documented in detail that can be used for future machine designs guidance.</p> / Doctor of Philosophy (PhD)
80

Cable Sizing and Its Effect on Thermal and Ampacity Values in Underground Power Distribution

Igwe, Obinna E. 01 January 2016 (has links)
Over the past decade, underground power distribution has become increasingly popular due to its reliability, safety, aesthetic characteristics, as well as the ever increasing focus on the environmental impacts of the various stages of power generation and distribution. With the technological advances in this area, the process of running these cables have become more economical and efficient. This thesis explores the practice of grouping multiple three phase cables in a common conduit, using the duct bank process, and analyzes the thermal and ampacity consequences on the individual lines. This analysis is done in an effort to better define and understand the various limitations of the practice and explore future possibilities in its expansion.

Page generated in 0.0615 seconds