In 14th August 2003, the Northeast USA suffered its worst power outage event in history. The power disturbance spreading through the system caused mal-trips of the distance relay remote back-up protections, which indeed contributed to the power outage cascading a wide area. The power outage in the Northeast USA was constrained by the presence of HVDC interconnections between the HVAC networks in Ontario and New York. The system collapse did not progress beyond the HVDC interconnection interface with Quebec. The HVDC link can regulate the voltage and current therefore impacts on the performance of the protection and system stability. The distance relay mal-operations were one of the main cause of the Northeast USA blackout as well as the other recent major large area blackouts which were pointed out by the previous papers. This thesis is focus on investigate how HVDC interconnections contribute to maintaining the power system stability. The research work investigated the performance of a distance relay to faults and disturbance on networks containing HVDC interconnection. The research work was carried out by modelling and testing a classic signal processing distance relay in a simple AC network which was based on Kunder’s two areas system using MATLAB/SIMULINK at first. Then the modeled distance relay’s performance was investigated by combining the distance relay and a simple HVDC link based on the Kunder’s two areas system. The research work firstly combined the signal processing distance relay and the HVDC link together to investigate the distance relay’s performance when the protected feeder containing DC link. The distance relay’s performance was investigated when the protected feeders containing HVDC link under fault conditions and power swing conditions. For comparison, a similar power system without HVDC link was also simulated.

Thesis (doctoral)--Universität Köln.

A blackout is defined as the loss of electric power for a given period in a particular area. With increasing dependence on reliable electric power, the social and economic ramifications of blackouts are dire, negatively impacting the productivity, safety, and security of communities. To reduce blackout occurrence, power system planners incorporate redundancy and advanced controls to the grid to make it more adaptable to disturbances. However, adding redundant transmission lines is not only expensive, it is suboptimal in some contexts. While it is unattainable to have no blackout, it is possible and necessary to implement measures that minimize the likelihood and scale of these outages. This work proposes a solution that uses a microgrid with advanced energy storage and solar PV to mitigate blackouts in Kigali, the capital of Rwanda. A description and steady state analysis of major weaknesses in the Rwandan electric grid is presented. A microgrid application capable of islanding from the system is simulated in the steady state and shown to strengthen the system and decrease the likelihood of blackouts in Kigali. The composition of the microgrid is then designed, simulated, and optimized for technical and financial feasibility using the HOMER model. A microgrid that uses energy storage and solar PV is shown to not only be feasible, but also competitive with current costs of electricity in Rwanda. For comparison, different combinations that include diesel generation are also simulated. / Master of Science

Patients presenting with an abrupt loss of postural control are commonly said to have had ‘collapse?cause’. This is a common presentation, accounting for up to 6% of emergency department cases, and 3% of hospital admissions. However, collapse?cause is a ‘catch-all’ term and there are many different causes which include falls, transient ischemic attacks, cerebrovascular accidents, road traffic accidents, metabolic abnormalities, intoxication, and transient loss of consciousness, (TLOC or ‘blackout’). A majority of patients fall into the latter category. Where TLOC has occurred, the causes are syncope, epilepsy and psychogenic blackouts. The clinical features of these three conditions can often be similar, albeit with subtle differences. A wide variation exists in the way such patients are assessed, investigated and managed, who manages them and where. There is an absence of simple clinical tools for assessment, poor risk stratification, inappropriate and overuse of investigations. Hospitalisation is often unnecessary and misdiagnoses are common. In this thesis, the problem of TLOC has been addressed in four projects. Section 1 (Chapter II): reports a simple new risk stratification scheme for patients presenting with TLOC, assessed in a specialist nurse lead, cardiologist supervised (SP), Rapid Access Blackouts Triage Clinic - RABTC. Frequently, after triage, a patient may be deemed to be at low risk, but blackouts continue, the cause remains unclear, and conventional tests, have been unhelpful. In Chapter III, we describe the option of investigating such patients by long term (up to 3 years) ECG monitoring using an implantable loop recorder (ILR). In order to address the specific question of misdiagnosis of epilepsy where convulsive syncope might be the true diagnosis, the REVISE Study- REVeal in the Investigation of Syncope and Epilepsy was undertaken, which is described in Chapter IV. Lastly, convulsive syncope is the likely explanation for a misdiagnosis in patients diagnosed with epilepsy, but the incidence of cardiac disease in patients with brain injury and epilepsy is unknown. Therefore a cohort of patients in a residential epilepsy centre was studied. In this setting, residents typically had a history of brain injury and suffered from recurrent epileptic seizures. The findings of cardiology assessment are presented in Section 4 (Chapter V).

Alcohol-induced blackouts, or periods of anterograde amnesia without loss of consciousness, were a diagnostic indicator in Jellinek’s (1952) theory of alcoholism and have been correlated with alcohol use problems (Campbell & Hodgins, 1993; Goodwin, Crane, & Guze, 1969; Ryback, 1970; Tarter & Schneider, 1976). Other findings suggest that blackouts are a warning sign of problem drinking, but not a predictor of alcohol use disorders (Anthenelli, Klein, Tsuang, Smith, & Schuckit, 1994). Most published research on blackouts focuses on cognitive deficits among older alcohol-dependent adults, yet recent research indicates prevalence rates for blackouts as high as 50% among college students (White, Jamieson-Drake, & Swartzwelder, 2002). In addition, young adults who reported experiencing a blackout were later told that they had vandalized property, driven a car, or engaged in other risky behaviors without remembering (Buelow & Koeppel, 1995). Despite their high prevalence and associated negative consequences, relatively little is known about alcohol-induced blackouts or their neural, social, and behavioral correlates among non-dependent populations. The current research explored individual variation in memory functioning under sober and intoxicated conditions and alcohol’s effects on neural activation during memory processes. / text

This thesis investigates the engineering economics of interventions to reduce consumer inconvenience due to unreliable electricity supply in rural India. The work introduces and applies a novel approach to estimate interruption costs as loss in consumer surplus due to restricted consumption of electricity services. Chapter 2 reports an assessment that compares grid extension with distributed generation (DG) alternatives, based on the subsidies they will necessitate, and costs of service interruptions that are appropriate in the rural Indian context. Despite the inclusion of interruption costs, standalone DG does not appear to be competitive with grid extension at distances of less than 17 km. However, backing up unreliable grid service with local DG plants is attractive when reliability is very poor, even in previously electrified villages. Introduction of energy efficient lighting changes these economics, and the threshold for acceptable grid unreliability significantly reduces. Chapter 3 analyzes supply rostering (alternatively, “load shedding”) in metropolitan, small town and rural feeders in and around Bangalore city. The inequity in load shedding is analyzed through transfers due to differential tariffs between the urban and rural residential consumers, and the relief provided to BESCOM, through avoided procurement of additional supply from generators, because rural and small town feeders are load shed higher than Bangalore city. The values of the load shedding transfers are estimated to be in the range of Rs. 120-380/consumer-year from the rural consumers, and Rs. 220- 370/consumer-year from the small town consumers. The metropolitan consumers are found to be net beneficiaries. The viability of using smart meters to provide current limited but uninterrupted supply is investigated as one alternative to outright blackouts. Chapter 4 develops a broader theoretical framework that can be used to model consumer demand for electricity services with unreliable supply and adaptation. Demand for energy ‘services’ is modeled by incorporating time of use, duration and deferability. Supply reliability is disaggregated into its constituent dimensions– mean and variance of supply availability in times of high demand, and supply predictability, and their respective impacts on consumer welfare are discussed. Primary data collected from Karnataka inform the discussion, especially with backup adoption. New consumer-oriented reliability indices are proposed.

As our electric power distribution infrastructure has aged, considerable investment has been applied to modernizing the electrical power grid through weatherization and in deployment of real-time monitoring systems. A key question is whether or not these investments are reducing the number and duration of power outages, leading to improved reliability. Statistical methods are applied to analyze electrical disturbance data (from the Department of Energy, DOE) and reliability index data (from state utility public service commission regulators) to detect signs of improvement. The number of installed smart meters provided by several utilities is used to determine whether the number of smart meters correlate with a reduction in outage frequency. Indication emerged that the number of power outages may be decreasing over time. The magnitude of power loss has decreased from 2003 to 2007, and behaves cyclically from 2008 to 2014, with a few outlier points in both groups. The duration also appears to be decreasing between 2003-2014. Large blackout events exceeding 5 GW continue to be rare, and certain power outage events are seasonally dependent. There was a linear relationship between the number of customers and the magnitude of a power outage event. However, no relationship was found between the magnitude of power outages and time to restore power. The frequency of outages maybe decreasing as the number of installed smart meters has increased. Recommendations for inclusion of additional metrics, changes to formatting and semantics of datasets currently provided by federal and state regulators are made to help aid researchers in performing more effective analysis. Confounding variables and lack of information that has made the analysis diffcult is also discussed.

The purpose of this dissertation is to analyze dynamic behavior of a stressed power system and to correlate the dynamic responses to a near future system voltage abnormality. It is postulated that the dynamic response of a stressed power system in a short period of time-in seconds-contains sufficient information that will allow prediction of voltage abnormality in future time-in minutes. The PSSE dynamics simulator is used to study the dynamics of the IEEE 39 Bus equivalent test system. To correlate dynamic behavior to system voltage abnormality, this research utilizes two different pattern recognition methods one being algorithmic method known as Regularized Least Square Classification (RLSC) pattern recognition and the other being a statistical method known as Classification and Regression Tree (CART). Dynamics of a stressed test system is captured by introducing numerous contingencies, by driving the system to the point of abnormal operation, and by identifying those simulated contingencies that cause system voltage abnormality. Normal and abnormal voltage cases are simulated using the PSSE dynamics tool. The results of simulation from PSSE dynamics will be divided into two sets of training and testing set data. Each of the two sets of data includes both normal and abnormal voltage cases that are used for development and validation of a discriminator. This research uses stressed system simulation results to train two RLSC and CART pattern recognition models using the training set obtained from the dynamic simulation data. After the training phase, the trained pattern recognition algorithm will be validated using the remainder of data obtained from simulation of the stressed system. This process will determine the prominent features and parameters in the process of classification of normal and abnormal voltage cases from dynamic simulation data. Each of the algorithmic or statistical pattern recognition methods have their advantages and disadvantages and it is the intention of this dissertation to use them only to find correlations between the dynamic behavior of a stressed system in response to severe contingencies and the outcome of the system behavior in a few minutes into the future.

Avec l'extension de la dérégulation du système électrique, les réseaux électriques sont exploités de plus en plus près de leurs limites de sécurité et de stabilité. Les conditions d'exploitation des réseaux deviennent de plus en plus complexes. Dans cette situation, des blackouts se produisent plus fréquemment. Les blackouts à grande échelle provoquent d'énormes pertes économiques et sociales. Nous avons tout d'abord analysé 37 blackouts apparus dans le monde entre 1965 et 2005, classifié leurs caractéristiques selon des phases temporelles identifiées au préalable, résumé leurs mécanismes communs et suggéré quelques méthodes possibles pour la prévention des futurs blackouts. Il est ressorti de cette analyse que la cascade de surcharge et l'écroulement de tension sont de loin les incidents les plus fréquents dans les blackouts et qu'un système pour la prévention de ces incidents en temps réel est nécessaire. Basé sur les nouvelles technologies de surveillance et contrôle des réseaux de type WAMS (Wide-area measurement system en anglais), nous proposons un nouveau système de contrôle de la stabilité du réseau électrique en temps réel. Ce système peut fournir les solutions optimales pour éviter l'instabilité du réseau électrique et fonctionne à base de délestage. Le délestage, une méthode efficace pour éviter les blackouts, a été largement utilisé dans les réseaux électriques. Les plans de délestage actuels sont normalement préparés à l'avance selon l'estimation de l'état d'urgence du réseau. Cependant, les délestages prédéfinis ne peuvent parfois empêcher les blackouts dans certaines situations complexes et imprévues. De ce fait, nous avons proposé trois méthodes de délestage optimal en temps réel et des stratégies optimales associées qui se concentrent sur les situations imprévues et peuvent assurer la stabilité de tension et la stabilité transitoire après le délestage. En utilisant de plus un système intelligent de gestion d'énergie dans l'habitat qui permet d'adapter la consommation d'énergie à la disponibilité des ressources tout en maximisant le confort de l'usager, nos délestages sont réalisés "en douceur", c'est à dire sans mettre aucun client dans le noir. Ce concept est radicalement différent du délestage classique actuel.

Orientadora: Profa. Dra. Patrícia Teixeira Leite Asano / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Energia, 2015. / O Sistema Interligado Nacional Brasileiro é um sistema elétrico de potência de dimensões continentais que fornece uma fonte confiável de energia elétrica, no entanto, perturbações, como por exemplo, blecautes são passíveis de ocorrer, por isso se faz necessário considerar as medidas a fim de reduzir a sua duração e seus efeitos. Sabe-se que o processo de recomposição de um sistema elétrico, após perturbação que impede o fornecimento de energia elétrica, é uma atividade que visa restabelecer com rapidez e segurança a condição normal de operação até o atendimento pleno da carga desligada. No Brasil este processo inicia-se a partir de usinas equipadas com unidades geradoras de auto restabelecimento (black start), que permitem a energização de áreas próximas "geoelétricamente" dessas usinas. Para que um sistema de energia seja recomposto o mais rápido e de forma confiável, planos de recomposição detalhados são necessários, pois efetivamente reduz o impacto de um blecaute no sistema de energia, e consequentemente para a sociedade. Portanto, este projeto de pesquisa apresenta a avaliação dinâmica adotada pelo operador nacional do sistema e propõe a avaliação hidroenergética a partir da Usina Hidroelétrica Henry Borden no plano de restabelecimento de cargas prioritárias dependentes desta usina em cenários operativos distintos. O foco da avaliação dinâmica é analisar a viabilidade da inserção do bombeamento de água entre bacias ou rios com objetivo de verificar a viabilidade desta operação. Já o objetivo da avaliação hidroenergética será na determinação dos volumes mínimos e vazões necessárias para a garantia energética do atendimento da área geoelétrica de responsabilidade desta usina e for fim, a partir destas avaliações também é possível analisar se a transferência de água contribuirá para o atendimento de um montante maior de carga. / The Brazilian National Interconnected System is an electric power system of continental dimensions that provides a reliable source of electricity, however, disturbances such as blackouts are likely to occur, so it is necessary to consider measures to reduce its duration and its effects. It is known that the process of restoration of an electrical system after disturbance preventing the supply of electricity, is an activity that aims to restore quickly and safely to normal operating condition until full compliance with the off load. In Brazil this process starts from power plants equipped with auto restoration generating units (black start), which allow the energizing nearby areas "geo electrically" these plants. So a power system is recomposed as quickly and reliably, detailed recovery plans are necessary because effectively reduces the impact of a blackout in the power system, and consequently for society. So this research project presents the dynamic assessment adopted by the national system operator and proposes hydro energy assessment from the Henry Borden hydroelectric plant in restoring dependent priority loads plan for this plant in different operating scenarios. The focus of dynamic assessment is to analyze the feasibility of inserting the pumping of water from ponds or rivers in order to verify the viability of this operation. But the energy hydro objective of the evaluation is to determine the minimum volumes and necessary flows for energy guarantee the care of the geoelectric area of responsibility of this plant and for order from these assessments is also possible to analyze the transfer of water will help to meet a larger amount of charge.