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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.
1

A robust wide area measurement based controller for networks with embedded HVDC links

Agnihotri, Prashant 12 August 2016 (has links)
The advent of Wide-Area measurement Systems has spurred interest in the use of non-local feedback signals for power swing damping control. Although damping can be improved through generator excitation systems, dc links and other grid connected power electronic converters, the full potential of wide-area measurements can be realized by coordinating the strategies used for multiple controllable devices in a grid. These strategies also need to be robust to partial or complete loss of communication, changes in operating points, topology and equipment outages, improve damping of all the controllable swing modes, and have adequate stability margins to avoid destabilization of untargeted modes. This thesis investigates a control strategy for multi-infeed and multi-terminal (also referred to as multiple embedded dc links in this thesis) dc links using local frequency difference signals as well as the frequency difference signals obtained from other dc links. This strategy combines the advantages of the local frequency difference signal with the additional degrees of freedom provided by the use of non-local frequency difference signals, to achieve targeted and enhanced swing mode damping for the poorly damped modes. Since the strategy uses only a limited set of non-local signals, the signals may be directly communicated to the dc links without having to be centrally collated with other system-wide measurements. The key aspect of the proposed strategy is the use of a symmetric positive definite (spd) gain matrix. This results in enhanced damping for all controllable swing modes. Furthermore, loss of communication between the dc links does not destroy the symmetric positive definiteness and the gain elements can be tuned to selectively enhance damping of poorly damped modes. Eigenvalue sensitivity analysis and case studies on a 3 machine 9 bus and 16 machine 68 bus system with multiple HVDC links are presented to demonstrate the key attributes and the effectiveness of this strategy. / October 2016
2

WAVNet: wide-area virtual networks for dynamic provisioning of IaaS

Xu, Zheming, 徐哲明 January 2010 (has links)
published_or_final_version / Computer Science / Master / Master of Philosophy
3

Communication network modeling for simulation of wide area monitoring and control applications in power systems

MUDIYANSELAGE, SARANGA D. EDIRISINGHE DISSANAYAKE TENNAKOON 06 April 2013 (has links)
This thesis has mainly focused on investigating the effect of communication network on the power system operation. The main objective of this research has been to develop a set of communication network simulation tools and verify their suitability for realistic cosimulation of a power system and an associated data-communication network within a power system simulation environment. Based on a background study, a set of communication components have been developed for the PSCAD/EMTDC power system simulation software, which can simulate communication delay and packet losses. Furthermore, an analytical method based on queuing theory has also been developed to evaluate the communication delay and packet loss probability of a typical PMU-PDC communication network. Finally, the communication components developed in this thesis have been integrated into the simulation of a wide area power system application to investigate the effect of communication network parameters on the power system operation.
4

The Arab world on-line : Arab-American communities using the Internet

Najarian, Aida 05 1900 (has links)
No description available.
5

Communication network modeling for simulation of wide area monitoring and control applications in power systems

MUDIYANSELAGE, SARANGA D. EDIRISINGHE DISSANAYAKE TENNAKOON 06 April 2013 (has links)
This thesis has mainly focused on investigating the effect of communication network on the power system operation. The main objective of this research has been to develop a set of communication network simulation tools and verify their suitability for realistic cosimulation of a power system and an associated data-communication network within a power system simulation environment. Based on a background study, a set of communication components have been developed for the PSCAD/EMTDC power system simulation software, which can simulate communication delay and packet losses. Furthermore, an analytical method based on queuing theory has also been developed to evaluate the communication delay and packet loss probability of a typical PMU-PDC communication network. Finally, the communication components developed in this thesis have been integrated into the simulation of a wide area power system application to investigate the effect of communication network parameters on the power system operation.
6

Application of the systems engineering process to develop a wide area network communications system upgrade design /

Cole, Carl F. January 1994 (has links)
Report (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Abstract. Includes bibliographical references (leaves 138-139). Also available via the Internet.
7

A resource discovery protocol for modern computing environments /

Robinson, Ricky. January 2005 (has links) (PDF)
Thesis (Ph.D.) - University of Queensland, 2005. / Includes bibliography.
8

Analysis of internet industry in Hong Kong : using Hong Kong Telecom as the case study /

Tam, Fung-har, Wallis. January 1996 (has links)
Thesis (M.B.A.)--University of Hong Kong, 1996. / Includes bibliographical references (leaf 140-142).
9

Étude et développement d'un réseau de capteurs synchronisés à l'aide d'un protocole de communication sans fil dédié à l'Internet des objets / Study and development of synchronized sensors network using a wireless communication protocol dedicated to the Internet of Things

Gilbert, Johann 18 September 2018 (has links)
Depuis les 20 dernières années, l'essor de l'IoT et du "cloud computing" a conditionné le besoin dedéployer massivement, et globalement, des capteurs afin d'alimenter des bases de données et améliorerla précision des algorithmes d'analyse. Pour répondre à ces demandes, de nouveaux réseaux basés surles bandes de fréquences ISM ont été déployés. Nous avons donc appréhendé de façon complète cestechnologies afin de garantir une qualité maximale pour nos produits mais aussi proposer des conseilsjustes dans un secteur ou abus de langage et promesses de performances sont monnaie courante.Cependant, le nombre grandissant d'objets émettant sous la fréquence du gigahertz lève un doutequant à l'impact sur la santé des êtres vivants. Dès lors, coupler l'aspect non invasif des VLC avecl'Internet des Objets permettrait non seulement de réduire les risques pour les êtres humains maisaussi de limiter la saturation des bandes radio.Néanmoins, les techniques d'aujourd'hui consistent principalement en la réalisation de systèmesdiffusant l'information depuis une source unique vers plusieurs récepteurs, ce qui est l'inverse du paradigmede l'IoT. Dans cette étude, nous avons donc réalisé un nouveau design basé sur les VLC qui meten place une topologie de réseau en étoile 3. Ce système, basé sur un concentrateur disposant d'une ouplusieurs caméra en guise de photo-récepteurs, est optimisé pour plus d'autonomie. Ainsi, la vitessede transmission peut être gérée dynamiquement sans être connue par les autres éléments du système. / In the last 20 years, the coming up of Internet of Things and Cloud Computing has conditionedthe need to deploy sensors everywhere to feed databases and analytics. To meet this requirements,new kind of networks have been massively deployed based on the sub-gigahertz frequency which haveunknown effect on human health.Couple the non-invasive aspect of the Visible Light Communication (VLC) with IoT could notonly reduce potential risks for human health but also avoid radio band saturation. However, today'stechniques consist mainly in broadcast data from light sources to receivers which is the opposite of theIoT paradigm. In this study, we will present a new design where the gateway is not a classic photodiodebut a camera.With this camera based method, we are able to design a star network using VLC. Even if the datarate is not the same as standard method, we are now able to collect data emanating from many sensorsat once with only one photoreceptor. This system also includes the ability of discriminate LED matrix,which transfer the same data faster, and single LED. Finally, data rate can be handle autonomouslyby the system to provide an optimal data transfer.
10

Development and Verification of Control and Protection Strategies in Hybrid AC/DC Power Systems for Smart Grid Applications

Salehi Pour Mehr, Vahid 02 November 2012 (has links)
Modern power networks incorporate communications and information technology infrastructure into the electrical power system to create a smart grid in terms of control and operation. The smart grid enables real-time communication and control between consumers and utility companies allowing suppliers to optimize energy usage based on price preference and system technical issues. The smart grid design aims to provide overall power system monitoring, create protection and control strategies to maintain system performance, stability and security. This dissertation contributed to the development of a unique and novel smart grid test-bed laboratory with integrated monitoring, protection and control systems. This test-bed was used as a platform to test the smart grid operational ideas developed here. The implementation of this system in the real-time software creates an environment for studying, implementing and verifying novel control and protection schemes developed in this dissertation. Phasor measurement techniques were developed using the available Data Acquisition (DAQ) devices in order to monitor all points in the power system in real time. This provides a practical view of system parameter changes, system abnormal conditions and its stability and security information system. These developments provide valuable measurements for technical power system operators in the energy control centers. Phasor Measurement technology is an excellent solution for improving system planning, operation and energy trading in addition to enabling advanced applications in Wide Area Monitoring, Protection and Control (WAMPAC). Moreover, a virtual protection system was developed and implemented in the smart grid laboratory with integrated functionality for wide area applications. Experiments and procedures were developed in the system in order to detect the system abnormal conditions and apply proper remedies to heal the system. A design for DC microgrid was developed to integrate it to the AC system with appropriate control capability. This system represents realistic hybrid AC/DC microgrids connectivity to the AC side to study the use of such architecture in system operation to help remedy system abnormal conditions. In addition, this dissertation explored the challenges and feasibility of the implementation of real-time system analysis features in order to monitor the system security and stability measures. These indices are measured experimentally during the operation of the developed hybrid AC/DC microgrids. Furthermore, a real-time optimal power flow system was implemented to optimally manage the power sharing between AC generators and DC side resources. A study relating to real-time energy management algorithm in hybrid microgrids was performed to evaluate the effects of using energy storage resources and their use in mitigating heavy load impacts on system stability and operational security.

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