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  • 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.
221

Digital computer solution of electromagnetic transients in large power systems

Navidbakhsh, Bijan 18 May 1973 (has links)
This thesis is an introduction to the solution of electromagnetic transients by a combination of the Bergeran method of characteristics and the application of trapezoidal rule of integration. Three test examples solved by digital computer illustrate the step by step solution and computer programming. To compare this method with the Laplace transformation technique, a test problem solved by both methods and also digital computer is illustrated. In conclusion, the advantages and disadvantages of both methods are compared
222

Secure Control and Operation of Energy Cyber-Physical Systems Through Intelligent Agents

El Hariri, Mohamad 05 November 2018 (has links)
The operation of the smart grid is expected to be heavily reliant on microprocessor-based control. Thus, there is a strong need for interoperability standards to address the heterogeneous nature of the data in the smart grid. In this research, we analyzed in detail the security threats of the Generic Object Oriented Substation Events (GOOSE) and Sampled Measured Values (SMV) protocol mappings of the IEC 61850 data modeling standard, which is the most widely industry-accepted standard for power system automation and control. We found that there is a strong need for security solutions that are capable of defending the grid against cyber-attacks, minimizing the damage in case a cyber-incident occurs, and restoring services within minimal time. To address these risks, we focused on correlating cyber security algorithms with physical characteristics of the power system by developing intelligent agents that use this knowledge as an important second line of defense in detecting malicious activity. This will complement the cyber security methods, including encryption and authentication. Firstly, we developed a physical-model-checking algorithm, which uses artificial neural networks to identify switching-related attacks on power systems based on load flow characteristics. Secondly, the feasibility of using neural network forecasters to detect spoofed sampled values was investigated. We showed that although such forecasters have high spoofed-data-detection accuracy, they are prone to the accumulation of forecasting error. In this research, we proposed an algorithm to detect the accumulation of the forecasting error based on lightweight statistical indicators. The effectiveness of the proposed algorithms was experimentally verified on the Smart Grid testbed at FIU. The test results showed that the proposed techniques have a minimal detection latency, in the range of microseconds. Also, in this research we developed a network-in-the-loop co-simulation platform that seamlessly integrates the components of the smart grid together, especially since they are governed by different regulations and owned by different entities. Power system simulation software, microcontrollers, and a real communication infrastructure were combined together to provide a cohesive smart grid platform. A data-centric communication scheme was selected to provide an interoperability layer between multi-vendor devices, software packages, and to bridge different protocols together.
223

Comparing current consistency and electrical resistance of wearable photovoltaic cells pre- and post-laundering and pre- and post-corrosion resistance testing conditions.

Talukder, Amit 08 August 2023 (has links) (PDF)
Photovoltaic(PV) technology is promising due to its natural availability among energy harvesting technologies. There is a growing need for sustainable power sources that can function without being connected to a power source or needing regular battery replacements. Wearable PV cells are gaining popularity in different applications. However, most companies produce wearable PVs for terrestrial applications. Research on wearable PV applications for the marine environment remains limited because these cells suffer from several issues. This research compares commercially sourced wearable PV cells' maximum current consistency and electrical resistance for two testing conditions. The researcher followed standardized methods for these two laundering and corrosion testing conditions. The results revealed that current consistency values decreased over both types' laundering and corrosion testing conditions. However, electrical resistance values showed opposite trends. The findings of this study suggest that wearable PV cells may serve as a reliable source for powering electronic devices in marine environments.
224

Jahresprognose 2013 und Mittelfristprognose bis 2020 zur Stromerzeugung in Deutschland und Vergleich mit den Vorgaben der "Leitstudie 2010"

Kobe, Sigismund 23 July 2013 (has links)
No description available.
225

Modeling and Simulation of Parallel D-STATCOMs with Full-Wave Rectifiers

Brinsfield, Jason 01 May 2014 (has links) (PDF)
In recent years, both a significant increase in electrical demand and a large influx of intermittent renewable energy sources have put a considerable stress on the nation’s electrical grid. Conventional power flow control techniques such as capacitor banks and tap-changing transformers are incapable of adequately handling the rapid fluctuations in power supply and demand that today’s grid experiences. Flexible AC Transmission System (FACTS) controllers are a practical way to compensate for such rapid power fluctuations. One type of shunt FACTS controller is the Static Synchronous Compensator (STATCOM), which uses fully controllable switches to source or sink reactive power to a point on the grid, thus reducing voltage fluctuations due to load changes. The purpose of this thesis is to model and simulate the operation of two Distribution STATCOMs (D-STATCOMs) operating on the same point on the grid. These D-STATCOMs also utilize parallel full-wave rectifiers that directly connect the ac grid to the dc capacitor of the D-STATCOMs. Parameters such as power loss, reaction time, stability, and THD are measured for several test scenarios. Results from this thesis show that two D-STATCOMs operating on the same point can be stable and effective under a wide range of conditions. This thesis also concludes that the inclusion of parallel rectifiers with the D-STATCOMs results in no performance improvement of the D-STATCOMs.
226

Adaptive Automotive Lighting Systems

Haeberlin, Marc W 01 June 2015 (has links) (PDF)
Over the past few years, the use of LEDs within the automotive and avionic industries has increased due to their high efficiency, durability and wide range of light brightness. As the use of LEDs within these industries grows, a need for reliable, high performance drivers becomes more relevant. Companies are implementing LEDs for applications involving adaptive lighting or simple dimming features. This thesis shows implementation of various non-isolated analog converters integrated with digital dimmers to achieve these adaptive lighting systems. Adaptive lighting systems involve reading an input from an external source (brake pedal or steering wheel) and changing the brightness and/or pattern of the brake/headlights to convey more information to the driver and their surroundings. The analog converters will implement Linear Technology’s LED driver IC’s, while the digital dimmers comprise of microcontrollers and discrete components. The design, simulation, and hardware verification will showcase the abilities of these analog converters. Results will demonstrate the proposed applications for both adaptive front and brake lighting.
227

Voltage Stability Analysis Using Simulated Synchrophasor Measurements

Agatep, Allan 01 May 2013 (has links) (PDF)
An increase in demand for electric power has forced utility transmission systems to continuously operate under stressed conditions, which are close to instability limits. Operating power systems under such conditions along with inadequate reactive power reserves initiates a sequence of voltage instability points and can ultimately lead to a system voltage collapse. Significant research have been focused on time-synchronized measurements of power systems which can be used to frequently determine the state of a power system and can lead to a more robust protection, control and operation performance. This thesis discusses the applicability of two voltage stability synchrophasor-based indices from literature to analyze the stability of a power system. Various load flow scenarios were conducted on the BPA 10-Bus system and the IEEE 39-Bus System using PowerWorld Simulator. The two indices were analyzed and compared against each other along with other well-known methods. Results show that their performances are coherent to each other regarding to voltage stability of the system; the indices can also predict voltage collapse as well as provide insight on other locations within the system that can contribute to instability.
228

Smart Wall Outlet Design and Implementation for the DC House Project

Mendoza, Kevin Roy 01 June 2014 (has links) (PDF)
Most everyday AC appliances are designed to operate off of 120V coming from the wall outlet in our homes. This voltage is a standard set from our established infrastructure. Unlike AC devices, DC devices do not have any set standard of voltage they all will run off of. This presents a problem for the DC house as the various loads that will be used will have different required input voltages. One set voltage for a wall outlet will not suffice for the DC House. This Smart Wall Outlet is designed with a DC-DC converter that will have its output voltage controlled by an on-board microprocessor. The Smart Wall Outlet detects current going into a device, and will adjust the voltage applied to the device to ensure it operates most efficiently. Proof of concept research has already been performed in the past, and this thesis will look towards implementing this concept on a single circuit board.
229

Design and Analysis of a Single-Stage Inverter Using Parallel DC-DC Converters for Solar Cell Application

Leonides, Gabriel 01 August 2021 (has links) (PDF)
This thesis introduces the design and analysis of a single-stage inverter. A circuit was designed and simulated as a proof of concept to investigate the possibility of using boost and buck-boost converters to provide an AC output. The proposed circuit utilizes non-synchronous boost and buck-boost converters due to their simplicity in control signals as opposed to synchronous converters. The application of the proposed inverter is for use with individual solar cells. The aim of the inverter for a single cell is to improve the efficiency of a solar panel, whose performance is limited to the performance of the least efficient cell. With each cell independent of any other cell in the solar panel, the overall efficiency of the panel can be improved. This circuit uses a 3.6VDC input from the solar cell to produce a 10VPP 60Hz square wave output. The inverter consists of a solar cell, two DC-DC converters, two linear dropout (LDO) regulators, a square wave generator, and a switching circuit . The design and analysis of all parts were investigated individually in detail. The different parts of the circuit were then simulated using LTspice before testing the overall circuit. Simulation results demonstrate the feasibility of the proposed inverter with all design requirements but efficiency meeting or exceeding the goals.
230

Multiple Input Single Output Converter with Uneven Load Sharing Control for Improved System Efficiency

Chan, Kristen Y 01 May 2020 (has links) (PDF)
This paper presents the development and study of multiple-input single-output converter (MISO) for the DC House project that utilizes a controller to maximize the overall converter’s efficiency. The premise of this thesis is to create uneven load current sharing between the converters at different loading conditions in order to maximize the efficiency of the overall MISO converter. The goal is to find a proper ratio of current from each converter to the total load current of the MISO system to achieve the greatest efficiency. The Arduino microcontroller is implemented to achieve this goal. The design and operation of the MISO converter with the proposed controller will be explained in this paper. The design and operation of the converter was tested and verified through simulation in LTSpice in addition to hardware implementation. Different ratios of current from each converter were used to fully test the MISO converter. For the 5A and 6A load current, the maximum efficiencies were reached with the 70% / 30% ratio case, with efficiencies of 94.91% and 95.07%, respectively. For 7A load current, the maximum efficiency was reached with the 60% / 40% ratio case, with an efficiency of 94.59%. The results were then compared with those obtained from the equal current sharing cases. For the cases tested, the efficiency of the unequal current sharing outperforms that obtained from the equal current sharing method.

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