Uma abordagem paramétrica do impacto da geração distribuída sobre as correntes de curto-circuito e na proteção de redes de distribuição.

Esta dissertação tem por propósito analisar os impactos da geração distribuída sobre as correntes de curto-circuito e sobre a proteção das redes de média tensão das concessionárias de distribuição de energia elétrica usando uma abordagem paramétrica. A principal motivação deste trabalho são os recentes incentivos regulatórios que estão fomentando a geração distribuída no Brasil. Contudo, as redes de distribuição convencionais foram projetadas para serem passivas e a introdução da geração poderá causar problemas de ordem técnica que ainda precisam ser resolvidos. Tais problemas foram pesquisados e aqueles relacionados com os impactos sobre as correntes de curto-circuito foram enfatizados. As normas técnicas das concessionárias também foram investigadas porque seus requisitos, como a ligação dos transformadores de acoplamento, influem nas correntes de curto-circuito. Para se calcular as correntes de curto-circuito, desenvolveu-se uma planilha eletrônica cujos resultados foram validados com programas comerciais de análise de redes elétricas. Esta ferramenta foi utilizada para demonstrar, através de exemplos, o impacto causado pela geração distribuída sobre as correntes de curto-circuito e, posteriormente, para realizar as análises paramétricas nas quais a influência de cada variável foi avaliada. A aplicação do método paramétrico permitiu o estudo de possíveis limites para a potência de um gerador distribuído em função dos impactos admissíveis, de seu ponto de conexão, de seus parâmetros elétricos e dos parâmetros elétricos da rede.

Compactação e elevação da vida útil de transformadores de distribuição empregando óleo vegetal isolante.

A busca no aumento da vida útil dos transformadores de distribuição, redução dos custos de manutenção e mitigação de falhas, leva ao desenvolvimento de novos materiais e critérios de exploração diferenciados desses ativos. Esta pesquisa apresenta o desenvolvimento de um novo transformador de distribuição compacto e mais eficiente utilizando óleo vegetal isolante totalmente biodegradável. Além de biodegradável, o óleo vegetal utilizado possui menor agressividade ambiental e maior capacidade térmica aumentando, a capacidade de carregamento do transformador sem comprometer a sua vida útil. A fim de atestar essa menor agressividade em relação ao óleo mineral, ensaios foram efetuados em um equipamento que permaneceu 12 anos em operação. O equipamento foi totalmente desmontado para análise e coleta de amostras de papel e óleo vegetal isolante. As análises visam comprovar a menor agressividade em relação ao óleo mineral, apresentadas na revisão bibliográfica. A menor agressividade torna possível a proposição de uma nova filosofia de planejamento de redes de distribuição utilizando uma quantidade menor dos novos transformadores para uma mesma carga, tornando-a mais compacta e eficiente.

Expert survey on priorities for the information society in the Caribbean

An on-line survey of experts was conducted to solicit their views on policy priorities in the area of information and communication technologies (ICT) in the Caribbean. The experts considered the goal to “promote teacher training in the use of ICTs in the classroom” to be the highest priority, followed by goals to “reduce the cost of broadband services” and “promote the use of ICT in emergency and disaster prevention, preparedness and response.” Goals in the areas of cybercrime, e-commerce, egovernment, universal service funds, consumer protection, and on-line privacy rounded out the top 10. Some of the lowest ranked goals were those related to coordinating the management of infrastructure changes. These included the switchover for digital terrestrial television (DTT) and digital FM radio, cloud computing for government ICT, the introduction of satellite-based internet services, and the installation of content distribution networks (CDNs). Initiatives aimed at using ICT to promote specific industries, or specific means of promoting the digital economy, tended toward the centre of the rankings. Thus, a general pattern emerged which elevated the importance of focusing on how ICT is integrated into the broader society, with economic issues a lower priority, and concerns about coordination on infrastructure issues lower still.

Modeling of Distributed Generation under Next Generation Interconnection Requirements

Thesis (Master's)--University of Washington, 2016-06

Interval data without sign restrictions in DEA

Conventional DEA models assume deterministic, precise and non-negative data for input and output observations. However, real applications may be characterized by observations that are given in form of intervals and include negative numbers. For instance, the consumption of electricity in decentralized energy resources may be either negative or positive, depending on the heat consumption. Likewise, the heat losses in distribution networks may be within a certain range, depending on e.g. external temperature and real-time outtake. Complementing earlier work separately addressing the two problems; interval data and negative data; we propose a comprehensive evaluation process for measuring the relative efficiencies of a set of DMUs in DEA. In our general formulation, the intervals may contain upper or lower bounds with different signs. The proposed method determines upper and lower bounds for the technical efficiency through the limits of the intervals after decomposition. Based on the interval scores, DMUs are then classified into three classes, namely, the strictly efficient, weakly efficient and inefficient. An intuitive ranking approach is presented for the respective classes. The approach is demonstrated through an application to the evaluation of bank branches. © 2013.

Pushing the Quality Level in Networked News Business: Semantic-Based Content Retrieval and Composition in International News Publishing

Electronic publishing exploits numerous possibilities to present or exchange information and to communicate via most current media like the Internet. By utilizing modern Web technologies like Web Services, loosely coupled services, and peer-to-peer networks we describe the integration of an intelligent business news presentation and distribution network. Employing semantics technologies enables the coupling of multinational and multilingual business news data on a scalable international level and thus introduce a service quality that is not achieved by alternative technologies in the news distribution area so far. Architecturally, we identified the loose coupling of existing services as the most feasible way to address multinational and multilingual news presentation and distribution networks. Furthermore we semantically enrich multinational news contents by relating them using AI techniques like the Vector Space Model. Summarizing our experiences we describe the technical integration of semantics and communication technologies in order to create a modern international news network.

Application of automatic load transfer on feeder utilisation balance

This paper looks at how automatic load transfer may be used as a possible planning tool to help deliver faster connections for customers. A trial on an area of overhead line Network is presented to show how improvements in % feeder utilisation may be realised by changing the location of the open point. The reported Network data is compared to calculated data under two different configurations over a two week trial period. The results show that ALT open point determination in the presence of generation is different from a load only circuit and that the open points may not be fixed with time. Looking at improvements in Network headroom may not be conducive to other improvements in the network such as loss reduction or improving voltage profiles.

Weather forecasting to predict practical dynamic asset rating of overhead lines

This paper describes the potential of pre-setting 11kV overhead line ratings over a time period of sufficient length to be useful to the real-time management of overhead lines. This forecast is based on short and long term freely available weather forecasts and is used to help investigate the potential for realising dynamic rating benefits on the electricity network. A comparison between the realisable benefits in ratings using this forecast data, over the period of a year has been undertaken.

Utilização da transformada de wavelet para detecção de variações anormais de tensão em sistemas elétricos com geração distribuída

The increasing demand in electricity and decrease forecast, increasingly, of fossil fuel reserves, as well as increasing environmental concern in the use of these have generated a concern about the quality of electricity generation, making it well welcome new investments in generation through alternative, clean and renewable sources. Distributed generation is one of the main solutions for the independent and selfsufficient generating systems, such as the sugarcane industry. This sector has grown considerably, contributing expressively in the production of electricity to the distribution networks. Faced with this situation, one of the main objectives of this study is to propose the implementation of an algorithm to detect islanding disturbances in the electrical system, characterized by situations of under- or overvoltage. The algorithm should also commonly quantize the time that the system was operating in these conditions, to check the possible consequences that will be caused in the electric power system. In order to achieve this it used the technique of wavelet multiresolution analysis (AMR) for detecting the generated disorders. The data obtained can be processed so as to be used for a possible predictive maintenance in the protection equipment of electrical network, since they are prone to damage on prolonged operation under abnormal conditions of frequency and voltage.

STPA-SafeSec: Safety and Security Analysis for Cyber-Physical Systems

Cyber-physical systems tightly integrate physical processes and information and communication technologies. As today’s critical infrastructures, e.g., the power grid or water distribution networks, are complex cyber-physical systems, ensuring their safety and security becomes of paramount importance. Traditional safety analysis methods, such as HAZOP, are ill-suited to assess these systems. Furthermore, cybersecurity vulnerabilities are often not considered critical, because their effects on the physical processes are not fully understood. In this work, we present STPA-SafeSec, a novel analysis methodology for both safety and security. Its results show the dependencies between cybersecurity vulnerabilities and system safety. Using this information, the most effective mitigation strategies to ensure safety and security of the system can be readily identified. We apply STPA-SafeSec to a use case in the power grid domain, and highlight its benefits.

Tietokantaratkaisuehdotus pientasajännitesähköverkoston mittausdatavarastoksi

Lappeenrannan teknillinen yliopisto tutkii pientasajännitesähkön käyttöä. Yliopisto on rakennuttanut Järvi-Suomen Energia Oy:n ja Suur-Savon Sähkö Oy:n kanssa yhteistyössä kokeellisen pientasajännitesähköverkon, jolla pystytään tarjoamaan kenttäolosuhteet pienjännitetutkimukselle todellisilla asiakkailla ja todentaa LVDC-teknologiaa ja muita älykkään sähköverkon toimintoja kenttäolosuhteissa. Verkon tasajänniteyhteys on rakennettu 20 kV sähkönjakeluverkon ja neljän kuluttajan välille. 20 kV keskijännite suunnataan tasamuuntamolla ±750 V pientasajännitteeksi ja uudestaan 400/230 V vaihtojännitteeksi kuluttajien läheisyydessä. Tämän kandidaatintyön tarkoituksena on luoda yliopistolle tietokanta pientasajännitesähköverkosta kertyvälle tiedolle ja mittaustuloksille. Tietokanta nähtiin tarpeelliseksi luoda, jotta pienjänniteverkon mittaustuloksia pystytään myöhemmin tarkastelemaan yhdessä ja yhtenäisessä muodossa. Yhdeksi tutkimuskysymykseksi muodostui, kuinka järjestää ja visualisoida kaikki verkosta palvelimille kertyvä mittausdata. Työssä on huomioitu myös kolme tietokantaa mahdollisesti hyödyntävää käyttäjäryhmää: kotitalousasiakkaat, sähköverkkoyhtiöt ja tutkimuslaboratorio, sekä pohdittu tietokannan hyötyä ja merkitystä näille käyttäjille. Toiseksi tutkimuskysymykseksi muodostuikin, mikä kaikesta tietokantaan talletetusta datasta olisi oleellisen tärkeää ottaa talteen näiden asiakkaiden kannalta, ja kuinka nämä voisivat hakea tietoa tietokannasta. Työn tutkimusmenetelmät perustuvat jo valmiiksi olemassa olevaan mittausdataan. Työtä varten on käytetty sekä painettua että sähköisessä muodossa olevaa kirjallisuutta. Työn tuloksena on saatu luotua tietokanta MySQL Workbench -ohjelmistolla, sekä mittausdatan keräys- ja käsittelyohjelmat Python-ohjelmointikielellä. Lisäksi on luotu erillinen MATLAB-rajapinta tiedon visualisoimista varten, jolla havainnollistetaan kolmen asiakasryhmän mittausdataa. Tietokanta ja sen tiedon visualisointi antavat kuluttajalle mahdollisuuden ymmärtää paremmin omaa sähkönkäyttöään, sekä sähköverkkoyhtiöille ja tutkimuslaboratorioille muun muassa tietoa sähkön laadusta ja verkon kuormituksesta.

Assessing the resilience of water supply systems in Oman

Water systems in the Sultanate of Oman are inevitably exposed to varied threats and hazards due to both natural and man-made hazards. Natural disasters, especially tropical cyclone Gonu in 2007, cause immense damage to water supply systems in Oman. At the same time water loss from leaks is a major operational problem. This research developed an integrated approach to identify and rank the risks to the water sources, transmission pipelines and distribution networks in Oman and suggests appropriate mitigation measures. The system resilience was evaluated and an emergency response plan for the water supplies developed. The methodology involved mining the data held by the water supply utility for risk and resilience determination and operational data to support calculations of non-revenue water. Risk factors were identified, ranked and scored at a stakeholder workshop and the operational information required was principally gathered from interviews. Finally, an emergency response plan was developed by evaluating the risk and resilience factors. The risk analysis and assessment used a Coarse Risk Analysis (CRA) approach and risk scores were generated using a simple risk matrix based on WHO recommendations. The likelihoods and consequences of a wide range of hazardous events were identified through a key workshop and subsequent questionnaires. The thesis proposes a method of translating the detailed risk evaluations into resilience scores through a methodology used in transportation networks. A water audit indicated that the percentage of NRW in Oman is greater than 35% which is similar to other Gulf countries but high internationally. The principal strategy for managing NRW used in the research was the AWWA water audit method which includes free to use software and was found to be easy to apply in Oman. The research showed that risks to the main desalination processes can be controlled but the risk due to feed water quality might remain high even after implementing mitigation measures because the intake is close to an oil port with a significant risk of oil contamination and algal blooms. The most severe risks to transmission mains were found to be associated with pipe rather than pump failure. The systems in Oman were found to be moderately resilient, the resilience of desalination plants reasonably high but the transmission mains and pumping stations are very vulnerable. The integrated strategy developed in this study has a wide applicability, particularly in the Gulf area, which may have risks from exceptional events and will be experiencing NRW. Other developing countries may also experience such risks but with different magnitudes and the risk evaluation tables could provide a useful format for further work.

Arquitetura para o desenvolvimento de unidades de medição fasorial sincronizada no monitoramento a nível de distribuição

This work presents a low cost architecture for development of synchronized phasor measurement units (PMU). The device is intended to be connected in the low voltage grid, which allows the monitoring of transmission and distribution networks. Developments of this project include a complete PMU, with instrumentation module for use in low voltage network, GPS module to provide the sync signal and time stamp for the measures, processing unit with the acquisition system, phasor estimation and formatting data according to the standard and finally, communication module for data transmission. For the development and evaluation of the performance of this PMU, it was developed a set of applications in LabVIEW environment with specific features that let analyze the behavior of the measures and identify the sources of error of the PMU, as well as to apply all the tests proposed by the standard. The first application, useful for the development of instrumentation, consists of a function generator integrated with an oscilloscope, which allows the generation and acquisition of signals synchronously, in addition to the handling of samples. The second and main, is the test platform, with capabality of generating all tests provided by the synchronized phasor measurement standard IEEE C37.118.1, allowing store data or make the analysis of the measurements in real time. Finally, a third application was developed to evaluate the results of the tests and generate calibration curves to adjust the PMU. The results include all the tests proposed by synchrophasors standard and an additional test that evaluates the impact of noise. Moreover, through two prototypes connected to the electrical installation of consumers in same distribution circuit, it was obtained monitoring records that allowed the identification of loads in consumer and power quality analysis, beyond the event detection at the distribution and transmission levels.

Adaptive edge analytics for distributed networked control of water systems

Over the last decade, there has been a trend where water utility companies aim to make water distribution networks more intelligent in order to improve their quality of service, reduce water waste, minimize maintenance costs etc., by incorporating IoT technologies. Current state of the art solutions use expensive power hungry deployments to monitor and transmit water network states periodically in order to detect anomalous behaviors such as water leakage and bursts. However, more than 97% of water network assets are remote away from power and are often in geographically remote underpopulated areas, facts that make current approaches unsuitable for next generation more dynamic adaptive water networks. Battery-driven wireless sensor/actuator based solutions are theoretically the perfect choice to support next generation water distribution. In this paper, we present an end-to-end water leak localization system, which exploits edge processing and enables the use of battery-driven sensor nodes. Our system combines a lightweight edge anomaly detection algorithm based on compression rates and an efficient localization algorithm based on graph theory. The edge anomaly detection and localization elements of the systems produce a timely and accurate localization result and reduce the communication by 99% compared to the traditional periodic communication. We evaluated our schemes by deploying non-intrusive sensors measuring vibrational data on a real-world water test rig that have had controlled leakage and burst scenarios implemented.

Combinatorial design of key distribution mechanisms for wireless sensor networks

Secure communications in wireless sensor networks operating under adversarial conditions require providing pairwise (symmetric) keys to sensor nodes. In large scale deployment scenarios, there is no prior knowledge of post deployment network configuration since nodes may be randomly scattered over a hostile territory. Thus, shared keys must be distributed before deployment to provide each node a key-chain. For large sensor networks it is infeasible to store a unique key for all other nodes in the key-chain of a sensor node. Consequently, for secure communication either two nodes have a key in common in their key-chains and they have a wireless link between them, or there is a path, called key-path, among these two nodes where each pair of neighboring nodes on this path have a key in common. Length of the key-path is the key factor for efficiency of the design. This paper presents novel deterministic and hybrid approaches based on Combinatorial Design for deciding how many and which keys to assign to each key-chain before the sensor network deployment. In particular, Balanced Incomplete Block Designs (BIBD) and Generalized Quadrangles (GQ) are mapped to obtain efficient key distribution schemes. Performance and security properties of the proposed schemes are studied both analytically and computationally. Comparison to related work shows that the combinatorial approach produces better connectivity with smaller key-chain sizes.