Dissertations / Theses on the topic 'Automation of electric power systems'

A comprehensive large-scale power system modeling is developed to facilitate the design and analysis of present and future spacecraft power systems. A two-port coupling method is utilized to provide a modularity in model building and analysis of the system. The modular approach allows the model to be flexible, verifiable and computationally efficient. A methodology for the system level analysis is presented with the ability to focus on the performance characteristics of an arbitrary component or subsystem. The system performance parameters are derived explicitly in terms of the two-port hybrid g-parameter representation of the component or subsystem, and impedances of its terminating subsystems. From this, the stability of the system is analytically determined and the subsystem interaction criteria is observed. Also presented is a model development from the empirical data employing the complex curve fitting technique. The technique is especially powerful for large scale system modeling and analysis where certain components and subsystems are viewed as black boxes with measurable terminal characteristics. The technique can also be used to realize a reduced order model of a complex subsystem. The Direct Energy Transfer (DET) spacecraft power system is modeled to demonstrate the versatility of the comprehensive system model by performing various DC, small-signal and large-signal analyses. Of particular interest is the analysis of the large-signal behavior of the nonlinear solar array system by employing the state-plane method. The analysis of the solar array system operation focused on the transition mode between the shunt mode and the battery discharging mode is presented. The subsystem interaction problems in the local component and global system are illustrated. A methodology for the design and trouble-shooting of a system dealing with the interaction problems using the g-parameters is described. Finally, a system level analysis of the DET system using an empirical data modeling technique is performed.
Ph. D.

The objective of the proposed research is to analyze automated residential energy management technology using primary energy source utilization. A residential energy management system (REMS) is an amalgamation of hardware and software that performs residential energy usage monitoring, planning, and control. Primary energy source utilization quantifies power system levels impacts on power generation cost, fuel utilization, and environmental air pollution; based on power system generating constraints and electric load. Automated residential energy management technology performance is quantified through a physically-based REMS simulation. This simulation includes individual appliance operation and accounts for consumer behavior by stochastically varying appliance usage and repeating multiple simulation iterations for each simulated scenario. The effect of the automated REMS under varying levels of control will be considered. Aggregate REMS power system impacts are quantified using primary energy source utilization. This analysis uses a probabilistic economic dispatch algorithm. The economic dispatch algorithm quantifies: fuel usage and subsequent environmental air pollution (EAP) generated; based on power system generating constraints and electric load (no transmission constraints are considered). The analysis will comprehensively explore multiple residential energy management options to achieve demand response. The physically-based REMS simulation will consider the following control options: programmable thermostat, direct load control, smart appliance scheduling, and smart appliance scheduling with a stationary battery. The ability to compare multiple automated residential energy management technology options on an equal basis will guide utility technology investment strategies.

Direct Load Control (DLC) -- the direct control of customer loads by an electric utility for the economic and reliable operation of the power system, is an important and active element of Load Management (LM). Currently attention has focussed on the integration of DLC into system operations. However, as yet, DLC is regarded as a discretionary resource to be used by the system operator based on informed judgment. The integration process has therefore, concentrated on improving the informational inputs to the operator. This dissertation extends the integration from that of a discretionary resource to a dispatchable system resource. The concept of the dynamic dispatch of DLC is formulated and defined to be an online evaluation and utilization of DLC for optimum benefit to the utility, as system conditions change. The concept envisages the use of DLC in an automated mode and coordinated with other system resources for optimum benefit. An important and integral part of the research effort is the development of a cost characterization of DLC. A closed form solution, using a dynamic programming framework, has been developed to estimate the costs of DLC dispatch. The derivation takes into account all operational constraints on the utilization of DLC -- payback characteristics, maximum on-times and minimum recovery times. The cost, defined as the difference in the fuel costs with and without DLC dispatch, were found to be dependent on the cost characteristics of the online generators and the load shape impacts of DLC dispatch. The dynamic dispatch concept is concretized by a power system operations model which incorporates DLC dispatch for fuel cost minimization and peak load shaving. The two modes are toggled by the dispatch algorithm as system conditions change. Results from the model are presented for several combinations of system conditions and DLC system parameters.
Ph. D.

Thesis submitted in fulfillment of the requirements for the degree Master of Technology: Electrical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology
The electric power distribution network, an essential section of the electric power system, supplies electrical power to the customer. Automating the distribution network allows for better efficiency, reliability, and level of work through the installation of distribution control systems. Presently, research and development efforts are focused in the area of communication technologies and application of the IEC 61850 protocol to make distribution automation more comprehensive, efficient and affordable. The aim of the thesis is to evaluate the relevance of the IEC61850 standard-based technology in the development and investigation of the distribution automation for a typical underground distribution network through the development of a distribution automation algorithm for fault detection, location, isolation and service restoration and the building of a lab scale test bench Distribution Automation (DA) has been around for many decades and each utility applies its developments for different reasons. Nowadays, due to the advancement in the communication technology, authentic and automatic reconfigurable power system that replies swiftly to instantaneous events is possible. Distribution automation functions do not only supersede legacy devices, but it allows the distribution network to function on another lever. The primary function of a DA system is to enable the devices on the distribution network to be operated and controlled remotely to automatically locate, isolate and reconnect supply during fault conditions. Utilities have become increasingly interested in DA due to the numerous benefits it offers. Operations, maintenance and efficiencies within substations and out on the feeders can be improved by the development of new additional capabilities of DA. Furthermore, the new standard-based technology has advanced further than a traditional Distribution Supervisory and Control Data Acquisition (DSCADA) system. These days the most important components of a DA system include Intelligent Electronic Devices (IEDs). IEDs have evolved through the years and execute various protection related actions, monitoring and control functions and are very promising for improving the operation of the DA systems. The thesis has developed an algorithm for automatic fault detection, location, isolation and system supply restoration using the functions of the IEC61850 standard-based technology. A lab scale system that would meet existing and future requirements for the control and automation of a typical underground distribution system is designed and constructed. The requirement for the lab scale distribution system is to have the ability to clear faults through reliable and fast protection operation, isolate faulted section/s, on the network and restore power to the unaffected parts of the network through automation control operation functions of the IEC61850 standard. Various tests and simulations have been done on the lab scale test bench to prove that the objective of the thesis is achieved. Keywords: IEC61850 Standard, Distribution automation, Distribution automation system, IEDs, Lab scale test bench, Protection, Algorithm for automatic control

Electro Hydrostatic Actuators (EHA) are emerging as a viable option for industrial machine builders as the design combines the best of both electro-mechanical and electro-hydraulic technologies. The EHA is a highly integrated, compact alternative to traditional hydraulic solutions. Automation engineers moving toward electro-mechanical actuation in pursuit of energy efficiency and environmental cleanliness, will find an EHA an attractive option for high force density actuators. This paper will address the factors to consider when assessing an industrial machine’s application suitability for this latest innovation in actuation. It describes principal base circuits, a concept for EHA building blocks and a realized pilot application as well as challenges on actuator and components level.

Thesis (Master of Engineering in Electrical Engineering))--Cape Peninsula University of Technology, 2018.
As far as substation automation systems are concerned, one of the prime requirements of most utilities today is the interoperability between Intelligent Electronic Devices (IEDs) of different manufacturers. The standard IEC 61850 - Communication Networks and Systems in Substations - allows such interoperability between IEDs for protection and automation of substations. Presently, many manufacturers have implemented, or are in the process of implementing this standard in their IEDs. This has encouraged some utilities to specify IEC is to ensure that both system requirements are met and the features and benefits of the standard are fully exploited. The author of this thesis investigated and brought forward the design of an integrated monitoring protection and control system of a network in Cape Peninsula University of Technology (CPUT) campus based of the IEC 61850 standard. A method of testing the physical IED based on Hardware-In-Loop (HIL) configuration with the Real-Time Digital Simulator (RTDS) is developed and implemented. Mapping of IED Substation Configuration Language (SCL) with that of the RTDS GTNET cards is discussed and implemented to further exploit the use of realtime testing with Generic Object Oriented Substation Event messages (GOOSE). The thesis highlight the benefits of interconnecting the reticulation IEDs into a standardised communication network for protection, control and monitoring of each substation event. This improves the access to information and reduces maintenance cost on the reticulation network.

An optimally designed thermosiphon for power electronics cooling is developed. There exists a need for augmented grid assets to facilitate power routing and decrease line losses. Power converter augmented transformers (PCATs) are critically limited thermally. Conventional active cooling system pumps and fans will not meet the 30 year life and 99.9% reliability required for grid scale implementation. This approach seeks to develop a single-phase closed-loop thermosiphon to remove heat from power electronics at fluxes on the order of 10 - 15 W/cm2. The passive thermosiphon is inherently a coupled thermal-fluid system. A parametric model and multi-physics design optimization code will be constructed to simulate thermosiphon steady state performance. The model will utilize heat transfer and fluid dynamic correlations from literature. A particle swarm optimization technique will be implemented for its performance with discrete domain problems. Several thermosiphons will be constructed, instrumented, and tested to verify the model and reach an optimal design.

Two key solutions to reduce the greenhouse gas emissions and increase the overall energy efficiency are to maximize the utilization of renewable energy resources (RERs) to generate energy for load consumption and to shift to low or zero emission plug-in electric vehicles (PEVs) for transportation. The present U.S. aging and overburdened power grid infrastructure is under a tremendous pressure to handle the issues involved in penetration of RERS and PEVs. The future power grid should be designed with for the effective utilization of distributed RERs and distributed generations to intelligently respond to varying customer demand including PEVs with high level of security, stability and reliability. This dissertation develops and verifies such a hybrid AC-DC power system. The system will operate in a distributed manner incorporating multiple components in both AC and DC styles and work in both grid-connected and islanding modes. The verification was performed on a laboratory-based hybrid AC-DC power system testbed as hardware/software platform. In this system, RERs emulators together with their maximum power point tracking technology and power electronics converters were designed to test different energy harvesting algorithms. The Energy storage devices including lithium-ion batteries and ultra-capacitors were used to optimize the performance of the hybrid power system. A lithium-ion battery smart energy management system with thermal and state of charge self-balancing was proposed to protect the energy storage system. A grid connected DC PEVs parking garage emulator, with five lithium-ion batteries was also designed with the smart charging functions that can emulate the future vehicle-to-grid (V2G), vehicle-to-vehicle (V2V) and vehicle-to-house (V2H) services. This includes grid voltage and frequency regulations, spinning reserves, micro grid islanding detection and energy resource support. The results show successful integration of the developed techniques for control and energy management of future hybrid AC-DC power systems with high penetration of RERs and PEVs.

Pour traiter les systèmes non linéaires, à grande échelle, multi-domaine tels que les systèmes électriques de puissance, nous avons remarqué dans les dernières années un intérêt croissant pour les techniques de modélisation, analyse et contrôle basées sur la notion d'énergie. L'énergie est en fait un concept fondamental en science et en ingénierie, où typiquement les systèmes dynamiques sont regardés comme des dispositifs de transformation d'énergie. Cette perspective est particulièrement utile pour étudier des systèmes non linéaires assez complexes, qui peuvent être décomposés en sous-systèmes plus simples, caractérisés au niveau énergétique, et qui, à travers leurs interconnexions, déterminent le comportement global du système tout entier. Il représente bien évidemment le langage le plus naturel et intuitif pour représenter les systèmes électriques de puissance. En particulier, l'utilisation de systèmes Hamiltoniens à Ports a eu un impact très fort dans différentes applications, plus précisément dans le cas de systèmes mécaniques, électriques et électromécaniques. Dans ce contexte alors, l'approche Hamiltonien à Ports représentent sans doute une base solide qui montre une nouvelle fac{c}on d'aborder les problèmes d'analyse et contrôle de systèmes électriques de puissance. Basée sur cette approche, la thèse est structurée en trois étapes fondamentales:1 - Modélisation d'une classe très générale de systèmes électriques de puissance, basée sur la théorie des graphes et la formulation en Systèmes Hamiltoniens à Ports des composantes.2 - Modélisation, analyse et commande de systèmes de transmission de courant continu haute tension. Avec l'intention de construire un pont entre la théorie et les éventuelles applications, un des objectifs fondamentaux consiste à établir des relations évidentes entre les solutions adoptées dans la pratique et les solutions obtenues à travers une analyse mathématique précise.3 - Travaux apparentés de l'auteur, dans différents domaines des systèmes électriques de puissance: systèmes ac conventionnels et micro réseaux
To deal with nonlinear, large scale, multidomain, systems, as power systems are, we have witnessed in the last few years an increasing interest in energy–based modeling, analysis and controller design techniques. Energy is one of the fundamental concepts in science and engineering practice, where it is common to view dynamical systems as energy-transformation devices. This perspective is particularly useful in studying complex nonlinear systems by decomposing them into simpler subsystems which, upon interconnection, add up their energies to determine the full systems behavior. This is obviously the most natural and intuitive language to represent power systems. In particular, the use of port–Hamiltonian (pH) systems has been already proven highly successful in many applications, namely for mechanical, electrical and electromechanical systems. The port-Hamiltonian systems paradigm theremore provides a solid foundation, which suggests new ways to look at power systems analysis and control problems.Based on this framework, this thesis is structured in three main steps.1 - Modelling of a generalized class of electric power systems, based on graph theory and port-Hamiltonian representation of the individual components.2 - Modelling, analysis and control of multiterminal hvdc transmission systems. With the intention to bridge the gap between theory and applications, one of the main concerns is to establish connections between existing engineering solutions, usually derived via ad hoc considerations, and the solutions stemming from theoretical analysis.3 - Additional contributions of the author in other fields of electric power systems, including traditional ac power systems an microgrids

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Electrical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology, 2012
The introduction of the IEC 61850 standard in substations for communication networks and systems by the International Electrotechnical Commission (IEC) in 2003 provided the possibility for communication between devices of different manufacturers. However, the advent of this standard also brought about many challenges associated with it. The challenges introduced by this fairly recent standard of communications in Substation Automation Systems (SAS), and the need for the development of cost effective IEC 61850- compliant devices, motivated the decision of the Centre for Substation and Energy Management Systems within the Electrical Engineering Department of the Cape Peninsula University of Technology to focus on the implementation of the IEC 61850 standard using an embedded hardware platform. The development of an IEC 61850 embedded application requires substantial knowledge in multiple domains such as data networking, software modelling and development of Intelligent Electronic Devices (IEDs), protection of the electrical system, system simulation and testing methods, etc. Currently knowledge about the implementation of the IEC 61850 standard usually resides with vendors and is not in the public domain. The IEC 61850 standard allows for two groups of communication services between entities within the substation automation system. One group utilizes a client-server model accommodating services such as Reporting and Remote Switching. The second group utilizes a peer-to-peer model for Generic Substation Event (GSE) services associated with time-critical activities such as fast and reliable communication between Intelligent Electronic Devices (IEDs) used for protection of the power network. The messages associated with the GSE services are the Generic Object Oriented Substation Event (GOOSE) messages. The use of GOOSE messages for protection of the electrical system is very important in modern substations. Detailed knowledge of the structure of these messages is important in instances requiring fault diagnosis to determine the cause of mal– operation or to address interoperability concerns or when developing custom IEC 61850- compliant devices with limited functionality. A practical protection application (overcurrent) case study is presented where GOOSE messages are exchanged between a commercial IED and an IEC 61850-compliant controller based on an embedded platform. The basic data model and software development of an actuator node for a circuit breaker is proposed using an IEC 61850 communication stack on an embedded platform. The performance of the GOOSE messages is confirmed to be as per the functional behaviour specified, and per the IEC 68150 standard in terms of the temporal behaviour required. This thesis document tables the methods, software programs, hardware interfacing and system integration techniques that allow for the development and implementation of a low cost IEC 61850-compliant controller unit on an embedded systems platform for the substation automation system. The overcurrent case study distributed between a commercial IED (SIEMENS Siprotec device) and the actuator application developed on an embedded platform for this project (DK60 board) is in compliance with the IEC 61850 standard and utilizing GOOSE messaging is successfully completed both in terms of functional and temporal behaviour. This novel research work contributes not only to the academic community, but to the international Power Systems community as a whole. Keywords: IEC 61850 standard, IEDs, GOOSE message, software modelling, software development, substation automation systems, communication stack, embedded systems, actuator.

A model of the accurate harmonic allocation methods is developed to improve the current emission limits of IEEE Std.519. IEC 61000-3-6 and IEEE Std. 519 have by now been accepted as two well known standards for interconnecting the MV and HV-EHV customers to utility systems and widely adopted as standards to many power utilities. It is worth noting that the harmonic current emission limits of both standards have not been compared and justified with analytical proofs because there is still no explanation that discusses the origin of the emission limits in IEEE Std. 519, or the complex feature of IEC 61000-3-6. Two new novel methods of allocating the harmonic current emission limits for MV customers and HV-EHV customers have been proposed. Both methods have been developed in accordance with the principles of IEC 61000-3-6. Task II has compared and investgated the emission limits of both IEC 61000-3-6 and IEEE Std. 519. The difference, inconsistency and inaccuracy have been proven with the perspective of practical evaluations based on their own principles. The investigations focus on the specific numerical proofs of the resulting voltage distortions and the current emission limits in the MV and HV-EHV systems rather than on the philosophies. The proposed methods strongly support IEC 61000-3-6 and IEEE Std. 519, and add to their value; these methods could also help utilities allocate fairly and accurately harmonic emission limits to their MV and HV-EHV customers.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
It is common the occurence of permanent faults in power distribution systems. In a typical radial power distribution system when the fault protection system operates, may cause power-off not only in the fault section, but also to all customers downstream the fault.Through disjunction devices normally closed along the feeder, and normaly open on its edges, is possible to isolate the faulty sector and reenergize the healthy ones, reducing the number of customers affected by a fault. Network operators normally do this procedure manually and in addition to demand a considerable ammount of time, is subject to errors on the part of the operator. In order to automate the analisys of the network and provided it of self-healing capacity, various methods have been proposed to solve this matter. Most of these approaches adopts a centralized strategy and do not address the aspect of electric power grid self-healing. In this work is proposed an approach that uses multi-agent systems for self-healing purposes of power distribution systems. Multi-agent are highly suitable for modelling distributed systems in the smart grid domain. For a safe recovery and without violation of operational restrictions the feeder agents perform an evaluation before device agents send any command to the network switches. The proposed multi-agent system is implemented in a agentâs development platform proposed in this work that uses the Python programming language. The platform is called PADE, Python Agent DEvelpment framework. The computer representation of the network, without simplifications, is accomplished by a data encoding based on the theory of graphs and named node-depth representation that serves as a basis for the development of an API of network representation that models each of the required components in the restoration analysis. The device agents communicate with IED that in turn control the switches in the network, by means of IEC 61850 protocols: GOOSE and MMS. To validate the proposed approach, computer simulations are performed using a simplified distribution power grid as a case study and a test platform with relay test case, protection and control IED, managed switch and embedded systems.
à comum a ocorrÃncia de faltas permanentes no sistema de distribuiÃÃo de energia elÃtrica. Por tratar-se de um sistema radial, a atuaÃÃo da proteÃÃo para estas faltas causa a desenergizaÃÃo nÃo sà do setor em falta, mas de todos os consumidores a jusante do setor onde ocorreu a falta. Fazendo uso dos dispositivos de disjunÃÃo normalmente fechados ao longo do alimentador e normalmente abertos nas suas bordas à possÃvel isolar o setor sob falta e re-energizar os setores sÃos, reduzindo o nÃmero de consumidores afetados por um defeito. Este procedimento à normalmente feito pelos operadores da rede, e alÃm de demandar um tempo considerÃvel, està sujeito à erros por parte do operador. No sentido de tornar automÃtica as anÃlises de restauraÃÃo da rede e prover o sistema da capacidade de auto-cura, tÃm sido propostas diversas metodologias para o problema. A maioria destas abordagens adota uma estratÃgia centralizada e nÃo abordam o aspecto de auto-cura da rede elÃtrica. Neste trabalho, à proposta uma abordagem utilizando sistemas multiagentes para recomposiÃÃo de setores de alimentadores de distribuiÃÃo de energia elÃtrica. A tÃcnica de sistemas multiagentes vem se mostrando bastante promissora no desenvolvimento de sistemas distribuÃdos em um contexto de redes elÃtricas inteligentes. Para que a recomposiÃÃo ocorra sem a violaÃÃo das restriÃÃes operacionais e de forma coerente, sÃo feitas anÃlises pelos agentes alimentadores antes que qualquer comando seja enviado para as chaves do sistema por meio de agentes dispositivo. O sistema multiagente proposto à implementado em uma plataforma de desenvolvimento de agentes proposta neste trabalho e que utiliza a linguagem de programaÃÃo Python. A plataforma tem o nome de PADE, Python Agent DEvelpment framework. A representaÃÃo computacional sem simplificaÃÃes da rede à proporcionada por uma codificaÃÃo de dados apoiada na teoria de grafos e denominada RepresentaÃÃo NÃ-Profundidade, que serve de base para o desenvolvimento de uma API de representaÃÃo da rede-elÃtrica que modela cada um dos componentes necessÃrios nas anÃlises de recomposiÃÃo. Ao agente dispositivo à dada a possibilidade de comunicaÃÃo com IED, que controlam as chaves do sistema, por meio dos protocolos da norma IEC 61850: GOOSE e MMS. Para validar a metodologia proposta sÃo realizadas simulaÃÃes computacionais utilizando uma rede de distribuiÃÃo simples como caso base e uma plataforma de testes com: mala de testes de relÃs, IED de proteÃÃo e controle de mercado, switch gerenciÃvel e placas de desenvolvimento de sistemas embarcados.

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Electrical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology 2014
The IEC 61850 standard, “Communication networks and systems in substations” was promulgated to accommodate the need for a common communication platform within substations for devices from different vendors. The IEC 61850 standard proposes a substation automation architecture that is Ethernet-based, with a “station-bus” for protection devices within the substation and a “process bus” where raw data from the voltage and current transformers are published onto the data network using a device known as a Merging Unit. To date, most of the standardization efforts were focused at the station bus level where event-triggered messages are exchanged between the substation automation devices, commonly referred to as Intelligent Electronic Devices (IEDs). These messages are known as Generic Object Oriented Substation Event messages. Equipment from vendors to accommodate the “process bus” paradigm, however is still limited at present. The Centre for Substation Automation and Energy Management Systems was established within the Electrical Engineering Department at the Cape Peninsula University of Technology with one of its objectives being the development of equipment either for simulation or real-time purposes in compliance with the IEC 61850 standard. In order to fulfil this long-term objective of the Centre, an in-depth understanding of the IEC 61850 standard is required. This document details the efforts at acquiring the requisite knowledge base in support of the educational objectives of the Centre and the research project implements a simulation of a merging unit which is compliant with the functional behavior as stipulated by the standard. This limited functional implementation (i.e. non-real-time) of the merging unit, is achieved through the development of a virtualized data acquisition node capable of synthetic generation of waveforms, encoding of the data and publishing the data in a format compliant with the IEC 61850-9-2 sampled value message structure. This functional behavior of the virtual sensor node which was implemented has been validated against the behavior of a commercial device and the sampled value message structure is validated against the standard. The temporal behavior of the proposed device is commented upon. This research project forms the basis for future real-time implementation of a merging unit.

Durante muito tempo a manutenÃÃo do sistema de distribuiÃÃo do campus do Pici da Universidade Federal do Cearà - UFC foi de responsabilidade da Companhia EnergÃtica do Cearà â Coelce, pela parceria entre os governos federal e estadual. No entanto, com a privatizaÃÃo da Coelce no ano de 1998, a UFC assumiu essa demanda e por muitos anos, por falta de recursos e planejamento, fez-se apenas intervenÃÃes corretivas emergenciais na infraestrutura existente, resultando em vÃrios problemas na continuidade de suprimento. Felizmente, os Ãltimos gestores atentaram para o problema e muitos investimentos na rede de distribuiÃÃo em mÃdia tensÃo estÃo sendo realizados, visando à modernizaÃÃo e melhoria da seguranÃa, disponibilidade e continuidade do suprimento de energia elÃtrica do campus do Pici. Estas aÃÃes tÃm embasamento tÃcnico nos estudos realizados pelo Departamento de Engenharia ElÃtrica em parceria com o setor de engenharia da UFC (UFC-Infra). Nesse contexto, foi idealizada e està em fase de implantaÃÃo uma subestaÃÃo de 69-13,8 kV, composta de dois transformadores de 5/6,25 MVA, sendo um de reserva, trÃs saÃdas de alimentadores e nove religadores distribuÃdos ao longo da rede de mÃdia tensÃo em 13,8 kV do campus. Este sistema serà operado, supervisionado e controlado por um sistema SCADA (Supervisory Control and Data Aquisition), desenvolvido na plataforma comercial Elipse Power, utilizando o banco de dados Microsoft SQL Server 2012 â versÃo Express. No Ãmbito da automaÃÃo, foi desenvolvida e integrada ao SCADA, via comunicaÃÃo OPC (Open Platform Communications), uma funÃÃo avanÃada denominada, Sistema de RecomposiÃÃo AutomÃtica (SRA-PICI). O SRA-PICI foi desenvolvido em linguagem C#, utilizando o programa Microsoft Visual Studio 2010, modelado em Redes de Petri Coloridas, e testado usando a ferramenta de anÃlise CPN Tools. Para integraÃÃo dos aplicativos SCADA e SRA foi utilizado o protocolo aberto OPC que especifica a comunicaÃÃo de dados em tempo real entre um elemento fonte e um elemento receptor de diferentes fabricantes. Testes de validaÃÃo do SRA e da comunicaÃÃo entre os aplicativos foram realizados em laboratÃrio, que atestam o sucesso da implementaÃÃo e abrem perspectivas importantes para avanÃar na direÃÃo de uma rede elÃtrica inteligente para o campus do Pici.
For a long time the maintenance of the power distribution system of the Pici Campus of the Federal University of Cearà - UFC was the responsibility of the Energy Company of Cearà - Coelce, by the partnership between the federal and state governments. However, with the privatization of Coelce in 1998, the UFC assumed that demand and for many years, due to lack of resources and planning, only the emergency and corrective interventions have taken place, thereby have emerged several problems in continuous supply. Fortunately, the last managers have paid attention to the problem and many investments in the medium voltage distribution network are being carried out, aimed at modernizing and improving security, availability and continuity of energy supply of Pici campus. These actions were based on technical studies conducted by the Department of Electrical Engineering in partnership with the engineering sector of the UFC (UFC-Infra). In this context, was designed and is being implemented a power substation of 69 to 13.8 kV, with two transformers of 5 / 6.25 MVA, , three outputs feeders and nine reclosers distributed throughout the medium voltage distribution network of the campus. This system will be operated, supervised and controlled by a SCADA system (Supervisory Control and Data Acquisition), developed in the commercial platform Elipse Power using the Microsoft SQL Server 2012 database - Express version. In the field of automation, it was developed and integrated into the SCADA via OPC (Open Communications Platform), an advanced function called Automatic Restoration System (ARS-PICI). The ARS-PICI was developed in C # using Microsoft Visual Studio 2010 program, modelled on Colored Petri Nets, and tested using the CPN Tools analysis program. For integration of the SCADA and the ARS application software was used the OPC open protocol that specifies the real time data communication between a source element and a receiving element from different manufacturers. Validation tests of the ARS and communication between the software SCADA-ARS were performed in the laboratory, attesting to the successful implementation and opening important perspectives to advance toward a smart grid to the campus of the Pici.

To combat global climate change, the reduction of carbon emissions in different industries, particularly the power industry, has been gradually moving towards a low-carbon profile to alleviate any irreversible damage to the planet and our future generations. Traditional fossil-fuel-based generation is slowly replaced by more renewable energy generation while it can be harnessed. However, renewables such as solar and wind are stochastic in nature and difficult to predict accurately. With the increasing content of renewables, there is also an increasing challenge to the planning and operation of the grid. With the rapid deployment of smart meters and advanced metering infrastructure (AMI), an emerging approach is to schedule controllable end-use devices to improve energy efficiency. Real-time pricing signals combined with this approach can potentially deliver more economic and environmental advantages compared with the existing common flat tariffs. Motivated by this, the thesis presents an automatic and optimal load scheduling framework to help balance intermittent renewables via the demand side. A bi-level consumer-utility optimization model is proposed to take marginal price signals and wind power into account. The impact of wind uncertainty is formulated in three different ways, namely deterministic value, scenario analysis, and cumulative distributions function, to provide a comprehensive modeling of unpredictable wind energy. To solve the problem in off-the-shelf optimization software, the proposed non-linear bi-level model is converted into an equivalent single-level mixed integer linear programming problem using the Karush-Kuhn-Tucker optimality conditions and linearization techniques. Numerical examples show that the proposed model is able to achieve the dual goals of minimizing the consumer payment as well as improving system conditions. The ultimate goal of this work is to provide a tool for utilities to consider the demand response model into their market-clearing procedure. As high penetration of distributed renewable energy resources are most likely applied to remote or stand-alone systems, planning such systems with uncertainties in both generation and demand sides is needed. As such, a three-level probabilistic sizing methodology is developed to obtain a practical sizing result for a stand-alone photovoltaic (PV) system. The first-level consists of three modules: 1) load demand, 2) renewable resources, and 3) system components, which comprise the fundamental elements of sizing the system. The second-level consists of various models, such as a Markov chain solar radiation model and a stochastic load simulator. The third-level combines reliability indices with an annualized cost of system to form a new objective function, which can simultaneously consider both system cost and reliability based on a chronological Monte Carlo simulation and particle swamp optimization approach. The simulation results are then tested and verified in a smart grid laboratory at the University of Hong Kong to demonstrate the feasibility of the proposed model. In summary, this thesis has developed a comprehensive framework of demand response on variable end-use consumptions with stochastic generation from renewables while optimizing both reliability and cost. Smart grid technologies, such as renewables, microgrid, storage, load signature, and demand response, have been extensively studied and interactively modeled to provide more intelligent planning and management for the smart grid.
published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy

The study of Power TAC is a Multi-Agent competitive simulation test-bed, providing opportunity to simulate research and developments of electronic agents which can manage the tasks of the consumers and energy resources in a virtual energy infrastructure. According to the Power TAC scenario, Plug-in Electrical Vehicles are a special type of consumers that interact with this infrastructure and sometimes with the producers through aggregators. The aim of this study is modeling an intelligent Plug-in Electric vehicle agent for Power TAC that acts as an intermediary between Power TAC grid and vehicle owners. The proposed agent acts autonomously and is capable of making decisions about its energy needs by learning the driving behaviors and other preferences of these vehicle owners in a specified time interval. These agents will be able to make decisions about buying energy from the grid when the charging process is necessary or sell their energy back to the grid when the conditions of the electricity market are sufficiently attractive. The objective of this study is to model a Multi-Agent system for automating the process of charging the plug-in Vehicle Agents in Power TAC scenario by determining the necessary agents and the simulation environment where the agents constructed and simulated. Аs results of this study, different strategies are defined by considering the preferences of the vehicle owners and the conditions of the vehicle; thereby the agents autonomously bid behalf of their user in order to automate the process of charging.

The objective of this thesis is to propose guidelines for advanced operation, control, and protection of the restructured distribution system by designing the architecture and functionality for autonomous operation of the distribution system with DGs. The proposed architecture consists of (1) autonomous state estimation and (2) applications that enable autonomous operation; in particular, three applications are discussed: setting-less component protection, instant-by-instant management, and short-term operational planning. Key elements of the proposed approach have been verified: (1) the proposed autonomous state estimation has been experimentally tested using laboratory test systems and (2) the feasibility of the setting-less component protection has been tested with numerical simulations.

This thesis proposes an algorithm and develops a program for fault detection and system restoration in medium voltage distribution systems. In Turkey, TUBITAK-UZAY developed distribution automation system including fault detection and service restoration functions for Bogazici Electricity Distribution Company. By the time, expanding of distribution system with nonstandardized infrastructure (for example more than one circuit breaker in the feeder, mesh and closed loop feeder structure), developed automation system have not properly worked under these unplanned situations. Taking into consideration of previously utilized TUBITAK Distribution Automation System (TUDOSIS), fault isolation algorithm is improved to cope with practical problems as non-standardized infrastructure and selectivity issue in protection system, and the proposed isolation algorithm is simulated. Further system restoration solution for mesh distribution systems is analyzed for distribution system in Turkey and expert system based algorithm is proposed.

[EN] The electricity sector is currently undergoing a process of liberalization and separation of roles, which is being implemented under the regulatory auspices of each Member State of the European Union and, therefore, with different speeds, perspectives and objectives that must converge on a common horizon, where Europe will benefit from an interconnected energy market in which producers and consumers can participate in free competition. This process of liberalization and separation of roles involves two consequences or, viewed another way, entails a major consequence from which other immediate consequence, as a necessity, is derived. The main consequence is the increased complexity in the management and supervision of a system, the electrical, increasingly interconnected and participatory, with connection of distributed energy sources, much of them from renewable sources, at different voltage levels and with different generation capacity at any point in the network. From this situation the other consequence is derived, which is the need to communicate information between agents, reliably, safely and quickly, and that this information is analyzed in the most effective way possible, to form part of the processes of decision taking that improve the observability and controllability of a system which is increasing in complexity and number of agents involved. With the evolution of Information and Communication Technologies (ICT), and the investments both in improving existing measurement and communications infrastructure, and taking the measurement and actuation capacity to a greater number of points in medium and low voltage networks, the availability of data that informs of the state of the network is increasingly higher and more complete. All these systems are part of the so-called Smart Grids, or intelligent networks of the future, a future which is not so far. One such source of information comes from the energy consumption of customers, measured on a regular basis (every hour, half hour or quarter-hour) and sent to the Distribution System Operators from the Smart Meters making use of Advanced Metering Infrastructure (AMI). This way, there is an increasingly amount of information on the energy consumption of customers, being stored in Big Data systems. This growing source of information demands specialized techniques which can take benefit from it, extracting a useful and summarized knowledge from it. This thesis deals with the use of this information of energy consumption from Smart Meters, in particular on the application of data mining techniques to obtain temporal patterns that characterize the users of electrical energy, grouping them according to these patterns in a small number of groups or clusters, that allow evaluating how users consume energy, both during the day and during a sequence of days, allowing to assess trends and predict future scenarios. For this, the current techniques are studied and, proving that the current works do not cover this objective, clustering or dynamic segmentation techniques applied to load profiles of electric energy consumption from domestic users are developed. These techniques are tested and validated on a database of hourly energy consumption values for a sample of residential customers in Spain during years 2008 and 2009. The results allow to observe both the characterization in consumption patterns of the different types of residential energy consumers, and their evolution over time, and to assess, for example, how the regulatory changes that occurred in Spain in the electricity sector during those years influenced in the temporal patterns of energy consumption.
[ES] El sector eléctrico se halla actualmente sometido a un proceso de liberalización y separación de roles, que está siendo aplicado bajo los auspicios regulatorios de cada Estado Miembro de la Unión Europea y, por tanto, con distintas velocidades, perspectivas y objetivos que deben confluir en un horizonte común, en donde Europa se beneficiará de un mercado energético interconectado, en el cual productores y consumidores podrán participar en libre competencia. Este proceso de liberalización y separación de roles conlleva dos consecuencias o, visto de otra manera, conlleva una consecuencia principal de la cual se deriva, como necesidad, otra consecuencia inmediata. La consecuencia principal es el aumento de la complejidad en la gestión y supervisión de un sistema, el eléctrico, cada vez más interconectado y participativo, con conexión de fuentes distribuidas de energía, muchas de ellas de origen renovable, a distintos niveles de tensión y con distinta capacidad de generación, en cualquier punto de la red. De esta situación se deriva la otra consecuencia, que es la necesidad de comunicar información entre los distintos agentes, de forma fiable, segura y rápida, y que esta información sea analizada de la forma más eficaz posible, para que forme parte de los procesos de toma de decisiones que mejoran la observabilidad y controlabilidad de un sistema cada vez más complejo y con más agentes involucrados. Con el avance de las Tecnologías de Información y Comunicaciones (TIC), y las inversiones tanto en mejora de la infraestructura existente de medida y comunicaciones, como en llevar la obtención de medidas y la capacidad de actuación a un mayor número de puntos en redes de media y baja tensión, la disponibilidad de datos sobre el estado de la red es cada vez mayor y más completa. Todos estos sistemas forman parte de las llamadas Smart Grids, o redes inteligentes del futuro, un futuro ya no tan lejano. Una de estas fuentes de información proviene de los consumos energéticos de los clientes, medidos de forma periódica (cada hora, media hora o cuarto de hora) y enviados hacia las Distribuidoras desde los contadores inteligentes o Smart Meters, mediante infraestructura avanzada de medida o Advanced Metering Infrastructure (AMI). De esta forma, cada vez se tiene una mayor cantidad de información sobre los consumos energéticos de los clientes, almacenada en sistemas de Big Data. Esta cada vez mayor fuente de información demanda técnicas especializadas que sepan aprovecharla, extrayendo un conocimiento útil y resumido de la misma. La presente Tesis doctoral versa sobre el uso de esta información de consumos energéticos de los contadores inteligentes, en concreto sobre la aplicación de técnicas de minería de datos (data mining) para obtener patrones temporales que caractericen a los usuarios de energía eléctrica, agrupándolos según estos mismos patrones en un número reducido de grupos o clusters, que permiten evaluar la forma en que los usuarios consumen la energía, tanto a lo largo del día como durante una secuencia de días, permitiendo evaluar tendencias y predecir escenarios futuros. Para ello se estudian las técnicas actuales y, comprobando que los trabajos actuales no cubren este objetivo, se desarrollan técnicas de clustering o segmentación dinámica aplicadas a curvas de carga de consumo eléctrico diario de clientes domésticos. Estas técnicas se prueban y validan sobre una base de datos de consumos energéticos horarios de una muestra de clientes residenciales en España durante los años 2008 y 2009. Los resultados permiten observar tanto la caracterización en consumos de los distintos tipos de consumidores energéticos residenciales, como su evolución en el tiempo, y permiten evaluar, por ejemplo, cómo influenciaron en los patrones temporales de consumos los cambios regulatorios que se produjeron en España en el sector eléctrico durante esos años.
[CAT] El sector elèctric es troba actualment sotmès a un procés de liberalització i separació de rols, que s'està aplicant davall els auspicis reguladors de cada estat membre de la Unió Europea i, per tant, amb distintes velocitats, perspectives i objectius que han de confluir en un horitzó comú, on Europa es beneficiarà d'un mercat energètic interconnectat, en el qual productors i consumidors podran participar en lliure competència. Aquest procés de liberalització i separació de rols comporta dues conseqüències o, vist d'una altra manera, comporta una conseqüència principal de la qual es deriva, com a necessitat, una altra conseqüència immediata. La conseqüència principal és l'augment de la complexitat en la gestió i supervisió d'un sistema, l'elèctric, cada vegada més interconnectat i participatiu, amb connexió de fonts distribuïdes d'energia, moltes d'aquestes d'origen renovable, a distints nivells de tensió i amb distinta capacitat de generació, en qualsevol punt de la xarxa. D'aquesta situació es deriva l'altra conseqüència, que és la necessitat de comunicar informació entre els distints agents, de forma fiable, segura i ràpida, i que aquesta informació siga analitzada de la manera més eficaç possible, perquè forme part dels processos de presa de decisions que milloren l'observabilitat i controlabilitat d'un sistema cada vegada més complex i amb més agents involucrats. Amb l'avanç de les tecnologies de la informació i les comunicacions (TIC), i les inversions, tant en la millora de la infraestructura existent de mesura i comunicacions, com en el trasllat de l'obtenció de mesures i capacitat d'actuació a un nombre més gran de punts en xarxes de mitjana i baixa tensió, la disponibilitat de dades sobre l'estat de la xarxa és cada vegada major i més completa. Tots aquests sistemes formen part de les denominades Smart Grids o xarxes intel·ligents del futur, un futur ja no tan llunyà. Una d'aquestes fonts d'informació prové dels consums energètics dels clients, mesurats de forma periòdica (cada hora, mitja hora o quart d'hora) i enviats cap a les distribuïdores des dels comptadors intel·ligents o Smart Meters, per mitjà d'infraestructura avançada de mesura o Advanced Metering Infrastructure (AMI). D'aquesta manera, cada vegada es té una major quantitat d'informació sobre els consums energètics dels clients, emmagatzemada en sistemes de Big Data. Aquesta cada vegada major font d'informació demanda tècniques especialitzades que sàpiguen aprofitar-la, extraient-ne un coneixement útil i resumit. La present tesi doctoral versa sobre l'ús d'aquesta informació de consums energètics dels comptadors intel·ligents, en concret sobre l'aplicació de tècniques de mineria de dades (data mining) per a obtenir patrons temporals que caracteritzen els usuaris d'energia elèctrica, agrupant-los segons aquests mateixos patrons en una quantitat reduïda de grups o clusters, que permeten avaluar la forma en què els usuaris consumeixen l'energia, tant al llarg del dia com durant una seqüència de dies, i que permetent avaluar tendències i predir escenaris futurs. Amb aquesta finalitat, s'estudien les tècniques actuals i, en comprovar que els treballs actuals no cobreixen aquest objectiu, es desenvolupen tècniques de clustering o segmentació dinàmica aplicades a corbes de càrrega de consum elèctric diari de clients domèstics. Aquestes tècniques es proven i validen sobre una base de dades de consums energètics horaris d'una mostra de clients residencials a Espanya durant els anys 2008 i 2009. Els resultats permeten observar tant la caracterització en consums dels distints tipus de consumidors energètics residencials, com la seua evolució en el temps, i permeten avaluar, per exemple, com van influenciar en els patrons temporals de consums els canvis reguladors que es van produir a Espanya en el sector elèctric durant aquests anys.
Benítez Sánchez, IJ. (2015). Dynamic segmentation techniques applied to load profiles of electric energy consumption from domestic users [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/59236
TESIS

Orientador: Carlos Alberto de Castro Junior
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
Made available in DSpace on 2018-08-06T19:37:05Z (GMT). No. of bitstreams: 1 Gomes_RicardoBorges_M.pdf: 725231 bytes, checksum: e24b9811f14e33910092b2f639a89050 (MD5) Previous issue date: 2006
Resumo: O método desacoplado rápido (MDR) [2] é uma variante do tradicional método de Newton [1] para a resolução do problema de fluxo de carga (obtenção do estado de operação de redes elétricas de potência). Sabe-se que o MDR apresenta desempenho insatisfatório quando aplicado a redes de distribuição, devido à desfavorável relação r/x dos ramos, resultando num processo de cálculo que pode apresentar divergência ou convergência lenta (grande número de iterações). Há algum tempo foi proposta uma alteração no MDR, chamada de rotação de eixos[4], que melhora as características de convergência do método. A idéia consiste em obter uma rede fictícia para a qual o MDR funcione bem e cujo estado de operação (magnitudes e ângulos de tensão) seja o mesmo da rede original. O valor do ângulo de rotação de eixos, único para toda a rede, é determinado empiricamente. Recentemente uma outra proposta de rotação ótima de eixos[5] foi apresentada, sugerindo modificações ao método que trouxeram maior automação aos cálculos, apesar de efeitos desfavoráveis em relação à manipulação de matrizes e ao significado físico da rede elétrica durante o processo iterativo. O presente trabalho traz um novo algoritmo de rotação de eixos que supera algumas desvantagens dos métodos apresentados em [4, 5], com bom desempenho. Além disso, traz uma interessante contribuição sobre a rotação de barras do tipo PV, não abordado anteriormente
Abstract: The fast decoupled loadflow (FDLF) [2] is a variant of the traditional Newton method [1] for solving the loadflow problem (find the operational state of electrical power networks). It is well-known that FDLF presents unsatisfactory performance when applied to distribution systems. Their unfavourable r/x branch ratios may lead to divergence or slow convergence (large number of iterations). A modification to the FDLF, called axesrotation[4], was proposed some time ago, which improves convergency of the method. The idea is to obtain a fictitious network for which the FDLF performs better and which operational state (voltage magnitudes and angles) is the same as the original network. However, the rotation angle is determined empirically. Recently the optimal axes rotation[5] was presented, suggesting some modifications that led to more automated calculations, despite of some undesirable effects on matrices handling and also to the physical meaning of networks during the iterative process. This research work presents a new algorithm for axes rotation that overcomes some disadvantages found in [4, 5], with good performance. Moreover, it brings an interesting contribution on the rotation of PV buses, not previously considered.
Mestrado
Energia Eletrica
Mestre em Engenharia Elétrica

Demand for Data Transfer between computers has increased ever since the introduction of Personal Computers (PC). Data Communicating on the Personal Computer is much more productive as it is an intelligent terminal that can connect to various hosts on the same I/O hardware circuit as well as execute processes on its own as an isolated system. Yet, the PC on its own is useless for data communication. It requires a hardware interface circuit and software for controlling the handshaking signals and setting up communication parameters. Often the data is distorted due to noise in the line. Such transmission errors are imbedded in the data and require careful filtering. The thesis deals with the development of a Data Acquisition system that collects real time load and weather data and stores them as historical database for use in a load forecast algorithm in a load management system. A filtering technique has been developed here that checks for transmission errors in the raw data. The microcomputers used in this development are the IBM PC/XT and the AT&T 3B2 supermicro computer.
Master of Science

The objective of the proposed research is to investigate feasible approaches to dynamic control of the power grid. Growth in the demand for electric power, and an increase in the penetration of renewable energy resources are causing congestion on an already aging power grid. Conventional grid control involves the use of static assets that operate on long time scales. These assets provide no dynamic control on the grid, and are typically used for scheduled support. Existing solutions (FACTS devices) to dynamic grid control have seen minimal market penetration because of high cost and low reliability. The proposed research provides a solution for dynamic control of the power grid that augments existing grid assets with a thin AC converter (TACC) to realize enhanced dynamic control. The TACC is a direct AC converter with filter elements and no bulk energy storage that dynamically reflects the asset value on the grid. The converter has a fail-normal mode of operation that returns the asset to its initial operating state, thereby not degrading system reliability. Some applications of TACCs include Inverter-Less STATCOMs and Controllable Network Transformers, which are realized by augmenting shunt VAR capacitors and load tap changers respectively. The principle of virtual quadrature sources is proposed to enable conditioning of AC voltages and currents. The concept is a novel method to realize control of phase angle and, or harmonics in single-phase AC converters, with no bulk energy storage. This concept is used to control the TACC and provides the asset with significantly enhanced control capabilities. Scaling of the TACC to utility voltage and power levels has been addressed by proposing a novel multilevel direct AC converter. The concept proposes the use of commercially available low cost semiconductor devices to realize high power converters. The specific application chosen to validate the concept of TACCs, through a medium voltage design, is the Inverter-less STATCOM.

A continuidade no fornecimento de energia elétrica a clientes é um objetivo constante das distribuidoras de energia, as quais estão constantemente buscando desenvolver soluções tecnológicas a fim de melhorar o desempenho das redes de distribuição. Com o crescimento das cargas eletrônicas e o expressivo aumento dos dispositivos automáticos nas redes, surge uma nova forma de analisar a rede de distribuição sob o aspecto da filosofia da proteção, considerando interrupções sustentadas e momentâneas, sob dois aspectos distintos, o primeiro considera o custo da energia não fornecida sob o período de contingência, enquanto que o segundo refere-se ao impacto do custo social para diferentes classes de clientes, durante o período das interrupções. Desta forma este trabalho propõe o desenvolvimento de uma estratégia de minimização de custos dessas interrupções considerando as características das cargas, bem como o tempo necessário para reinicialização da carga. Para este fim, é aplicado um modelo de programação não-linear, que emprega variáveis binárias para definir a habilitação ou não de curvas rápidas nos religadores e uma abordagem de otimização clássica. Os algoritmos foram desenvolvidos no software Matlab e posteriormente convertido para linguagem GAMS (Generic Algebraic Modeling System). A metodologia foi testada e validada em um alimentador de distribuição real urbano, localizado na região metropolitana de Porto Alegre (RS, Brasil).
Uninterrupted power delivery is a permanent goal of power utilities. One way of attaining this objective is constantly investing in technological solutions to improve the performance of distribution networks. With increasing loads, mainly electronic ones, as well as growing insertion of automatic reclosers, the protection philosophy of distribution systems has to be rethought taking into account temporary and permanent interruptions. In this work, we propose a strategy to minimize the cost of interruptions taking into account the load characteristics and the time required to restart the load. This is achieved by deriving a mixed integer nonlinear programming model. The proposed model uses binary variables to define if the instantaneous characteristic of the recloser should be enabled and a classical explicit mathematical optimization approach. The algorithms were developed with Matlab software and the conversion was made to a General Algebraic Modeling System (GAMS). The applicability of the proposed methodology is tested in an actual feeder from Porto Alegre.

This thesis develops methods to increase the amount of renewable energy sources that can be integrated into a power grid. The assessed methods include i) dynamic real-time assessment to enable the grid to be operated closer to its design limits; ii) energy storage and iii) coordinated control of distributed production units. Power grids using such novel techniques are referred to as “Smart Grids”. Under favourable conditions the use of these techniques is an alternative to traditional grid planning like replacement of transformers or construction of a new power line. Distributed Energy Resources like wind and solar power will impact the performance of the grid and this sets a limit to the amount of such renewables that can be integrated. The work develops the hosting capacity concept as an objective metric to quantify the ability of a power grid to integrate new production. Several case studies are presented using actual hourly production and consumption data. It is shown how the different variability of renewables and consumption affect the hosting capacity. The hosting capacity method is extended to the application of storage and curtailment. The goal is to create greater comparability and transparency, thereby improving the factual base of discussions between grid operators, electricity producers and other stakeholders on the amount and type of production that can be connected to a grid.Energy storage allows the consumption and production of electricity to be decoupled. This in turn allows electricity to be produced as the wind blows and the sun shines while consumed when required. Yet storage is expensive and the research defines when storage offers unique benefits not possible to achieve by other means. Focus is on comparison of storage to conventional and novel methods.As the number of distributed energy resources increase, their electronic converters need to provide services that help to keep the grid operating within its design criteria. The use of functionality from IEC Smart Grid standards, mainly IEC 61850, to coordinate the control and operation of these resources is demonstrated in a Research, Development and Demonstration site. The site contains wind, solar power, and battery storage together with the communication and control equipment expected in the future grids.Together storage, new communication schemes and grid control strategies allow for increased amounts of renewables into existing power grids, without unacceptable effects on users and grid performance.
Avhandlingen studerar hur existerande elnät kan ta emot mer produktion från förnyelsebara energikällor som vindkraft och solenergi. En metodik utvecklas för att objektivt kvantifiera mängden ny produktion som kan tas emot av ett nät. I flera fallstudier på verkliga nät utvärderas potentiella vinster med energilager, realtids gränser för nätets överföringsförmåga, och koordinerad kontroll av småskaliga energiresurser. De föreslagna lösningarna för lagring och kommunikation har verifierats experimentellt i en forskning, utveckling och demonstrationsanläggning i Ludvika.
Godkänd; 2014; Bibliografisk uppgift: Nicholas Etherden är industridoktorand på STRI AB i Göteborg. Vid sidan av doktoreringen har Nicholas varit aktiv som konsult inom kraftsystemsautomation och Smarta Elnät. Hans specialitet är IEC 61850 standarden för kommunikation inom elnät, vindkraftparker och distribuerad generering. Författaren har en civilingenjörsexamen i Teknisk fysik från Uppsala Universitet år 2000. Under studietiden läste han även kurser i kemi, miljökunskap och teoretisk filosofi. Han var under studietiden ordförande för Student Pugwash Sweden och ledamot International Network of Engineers and of Scientists for Global Responsibility (INES). Efter studietiden var han ordförande i Svenska Forskare och Ingenjörer mot Kärnvapen (FIMK). Han började sin professionella bana som trainee på ABB i Västerås där han spenderade sex år som utvecklare och grupp ledare för applikationsutvecklingen i ABB reläskydd. I parallell till arbete har han läst elkraft vid Mälardalenshögskola. År 2008 började han på STRI AB som ansvarig för dess IEC 61850 interoperabilitetslab. Han är på uppdrag av Svenska Kraftnät aktiv i ENTSO-E IEC 61850 specificeringsarbete och svensk representant i IEC tekniska kommitté 57, arbetsgrupp 10 som förvaltar IEC 61850 standarden. Han har hållit över 30 kurser i IEC 61850 standarden i fler än 10 länder.; 20140218 (niceth); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Nicholas Etherden Ämne: Elkraftteknik/Electric Power Engineering Avhandling: Increasing the Hosting Capacity of Distributed Energy Resources Using Storage and Communication Opponent: Professor Joao A Peças Lopes, Faculty of Engineering of the University of Porto, Portugal Ordförande: Professor Math Bollen, Avd för energivetenskap, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Tid: Måndag den 24 mars 2014, kl 09.00 Plats: Hörsal A, Campus Skellefteå, Luleå tekniska universitet
SmartGrid Energilager

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 103-115).
The electric power grid is recognized as an essential modern infrastructure that poses numerous canonical design and operational problems. Perhaps most critically, the inherently large scale of the power grid and similar systems necessitates fast algorithms. A particular complication distinguishing problems in power systems from those arising in other large infrastructures is the mathematical description of alternating current power flow: it is nonconvex, and thus excludes power systems from many frameworks benefiting from theoretically and practically efficient algorithms. However, advances over the past twenty years in optimization have led to broader classes possessing such algorithms, as well as procedures for transferring nonconvex problem to these classes. In this thesis, we approximate difficult problems in power systems with tractable, conic programs. First, we formulate a new type of NP-hard graph cut arising from undirected multicommodity flow networks. An eigenvalue bound in the form of the Cheeger inequality is proven, which serves as a starting point for deriving semidefinite relaxations. We next apply a lift-and-project type relaxation to transmission system planning. The approach unifies and improves upon existing models based on the DC power flow approximation, and yields new mixed-integer linear, second-order cone, and semidefinite models for the AC case. The AC models are particularly applicable to scenarios in which the DC approximation is not justified, such as the all-electric ship. Lastly, we consider distribution system reconfiguration. By making physically motivated simplifications to the DistFlow equations, we obtain mixed-integer quadratic, quadratically constrained, and second-order cone formulations, which are accurate and efficient enough for near-optimal, real-time application. We test each model on standard benchmark problems, as well as a new benchmark abstracted from a notional shipboard power system. The models accurately approximate the original formulations, while demonstrating the scalability required for application to realistic systems. Collectively, the models provide tangible new tradeoffs between computational efficiency and accuracy for fundamental problems in power systems.
by Joshua Adam Taylor.
Ph.D.

Thesis: Ph. D., Massachusetts Institute of Technology, Engineering Systems Division, 2015.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 235-240).
Scarce pipeline capacity in regions that rely on natural gas technologies for electricity generation has created volatile prices and reliability concerns. Gas-fired generation firms uniquely operate as large consumers in the gas market and large producers in the electricity market. To explore the effects of this coupling, this dissertation investigates decisions for firms that own gas-fired power plants by proposing a mixed-integer linear programming model that explicitly represents multi-year pipeline capacity commit- ments and service agreements, annual forward capacity offers, annual maintenance schedules, and daily fuel purchases and electricity generation. This dissertation's primary contributions consist of a detailed representation of a gas-fired power-plant owner's planning problem; a hierarchical application of a state-based dimensionality reduction technique to solve the hourly unit commitment problem over different tem- poral scales; a technique to evaluate a firm's forward capacity market offer, including a probabilistic approach to evaluate the risk of forced outages; a case study of New England's gas-electricity system; and an exploration of the applicability of forward capacity markets to reliability problems for other basic goods.
by Tommy Leung.
Ph. D.

Decreasing gas prices and the pressing need for fast-responding electric power generators are currently transforming natural gas networks. The intermittent operation of gas-fired plants to balance wind generation introduces spatiotemporal fluctuations of increasing gas demand. At the heart of modeling, monitoring, and control of gas networks is a set of nonlinear equations relating nodal gas injections and pressures to flows over pipelines. Given gas demands at all points of the network, the gas flow task aims at finding the rest of the physical quantities. For a tree network, the problem enjoys a closed-form solution; yet solving the equations for practical meshed networks is non-trivial. This problem is posed here as a feasibility problem involving quadratic equalities and inequalities, and is further relaxed to a convex semidefinite program (SDP) minimization. Drawing parallels to the power flow problem, the relaxation is shown to be exact if the cost function is judiciously designed using a representative set of network states. Numerical tests on a Belgian gas network corroborate the superiority of the novel method in recovering the actual gas network state over a Newton-Raphson solver. This thesis also considers the coupled infrastructures of natural gas and electric power systems. The gas and electric networks are coupled through gas-fired generators, which serve as shoulder and peaking plants for the electric power system. The optimal dispatch of coupled natural gas and electric power systems is posed as a relaxed convex minimization problem, which is solved using the feasible point pursuit (FPP) algorithm. For a decentralized solution, the alternating direction method of multipliers (ADMM) is used in collaboration with the FPP. Numerical experiments conducted on a Belgian gas network connected to the IEEE 14 bus benchmark system corroborate significant enhancements on computational efficiency compared with the centralized FPP-based approach.
Master of Science

Thesis (M.S. in Operations Research)--Naval Postgraduate School, March 2004.
Thesis advisor(s): Javier Salmeron, R. Kevin Wood. Includes bibliographical references (p. 69-70). Also available online.

De nos jours, la plupart des véhicules sont équipés de Directions Assistées Electriques (DAE). Ce type de systèmes d'aide à la conduite permet de réduire les efforts que le conducteur doit fournir pour tourner les roues. Ainsi, grâce à un moteur électrique, la DAE applique un couple additionnel en accord avec le comportement du conducteur et la dynamique du véhicule. Il est donc nécessaire de développer une commande en couple basée en particulier sur le signal provenant d'un capteur mesurant le couple agissant au niveau de la barre de torsion (correspondant à une image du couple conducteur). Ce composant est donc essentiel au fonctionnement de la DAE. Or, une défaillance de ce capteur entraine le plus souvent une coupure de l'assistance, pouvant mener à un risque d'accidents. Au regard de la sécurité fonctionnelle, un développement d'un mode de sécurité est recommandé, par de plus en plus de constructeurs automobiles. D'autre part, le marché des équipementiers automobiles reste un secteur très concurrentiel où une baisse des coûts de production est un challenge constamment recherché afin de gagner de nouvelles parts de marchés. Cet aspect de réduction du nombre de capteurs et d'analyse de la dynamique du véhicule s'inscrit donc dans le prolongement de la stratégie de sécurité. Cette thèse, menée au sein de JTEKT Europe, aborde ces divers enjeux. Après une présentation des différents systèmes de directions assistés électriques, des modèles sont présentés pour être utilisés lors de la conception de lois de commande et d'estimateurs. Ensuite deux méthodes d'estimation du couple conducteur sujet aux perturbations de la route et aux bruits de mesures sont proposées : la première est un observateur proportionnel intégral (PI) à synthèse mixte $H_infty/H_2$, et la seconde une approche par filtrage $H_infty$. Puis plusieurs stratégies de commande sont proposées suivant deux cas de figures distincts, soit en utilisant un observateur PI qui estime les états du système et le couple conducteur (LQR, commande LPV par retour d'état), soit en faisant abstraction d'estimateur de couple conducteur (commande $H_infty$ par retour de sortie dynamique). Ce dernier aspect présente l'avantage de nécessiter moins de mesures que le précédent. Ces approches ont été validées en simulation et mises en œuvre sur un véhicule prototype où des résultats prometteurs ont été obtenus
Nowadays, modern vehicles are equipped with more and more driving assistance systems, among them Electric Power Steering (EPS) helps the driver to turn the wheels. Indeed, EPS provides through an electric motor, an additional torque according to the driver's behaviour and the vehicle's dynamics to reduce the amount of effort required to the driver. Therefore, a torque control is developed based on the torque sensor signal which measures in practice the torsion bar torque (corresponding to an image of the driver torque). Consequently, this component is essential to the functioning of EPS systems.Indeed, a torque sensor failure usually leads to shut-off the assistance which may increase the risk of accident. Regarding functional safety, a back-up mode is recommended and required by more and more car manufacturers. On the other hand, a major challenge for automotive suppliers is to reduce cost production in order to meet growing markets demands and manage in the competitive sector. This issue considering a reduction of sensors' numbers and analysis of vehicle's dynamics is therefore an extension of applying the safety strategy. This thesis, carried out within JTEKT Europe, addresses these various issues.After introducing an overview of the different EPS systems, some models used for the design of controllers and estimators are presented. Then, two methods to estimate the driver torque subject to road disturbances and noise measurements are proposed: the first is a proportional integral observer (PI) with mixed synthesis $H_infty / H_2 $, whereas the second is an $ H_infty $ filtering approach. Then, several control strategies are proposed according to two different cases, either by using a PI observer which estimates the system states and the driver torque (LQR, LPV feedback control) or by not taking into account the driver torque estimation ($ H_infty $dynamic output feedback control). This latter approach has the advantage to require less measurements than the previous one. These approaches have been validated in simulation and implemented on a prototype vehicle where promising results have been obtained

Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010.
Committee Chair: Begovic, Miroslav; Committee Member: Divan, Deepak; Committee Member: Harley, Ron; Committee Member: Petit, Marc; Committee Member: Verriest, Erik. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M.S.)--University of Missouri--Rolla, 1989.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed October 7, 2008) Includes bibliographical references (p. 89).