Assignment (MPhil)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: The media, in its ongoing task to inform and educate South Africans, seemingly set the agenda in such a way that depicts poor black African people as the only racial group that is affected and infected by HIV/Aids. Photographs of poor black Africans are also used to inform and educate the public about the pandemic. In short, the media has set an agenda that has given HIV/Aids a black African face: vulnerable, helpless and living in squalid conditions. The hypothesis of this research is that it is racial stereotyping of poor black Africans, and that it is perpetuated by the Daily Dispatch and other media. It is also important to note that the voices of the affected and infected are not prominent in news reports about the pandemic. Their stories are either told by the journalists themselves or someone else as a spokesperson. The media must begin to give space to the heroes and heroines who are affected and infected by the HIV/Aids pandemic to tell their stories in their own words. Qualitative content analysis of the Daily Dispatch from 1 to 31 December 2004 was conducted. News stories, photographs, headlines and captions were analysed. This analysis shows that the voices of the affected and infected are still lacking in news reports and that poor black African people are used as the only visuals in HIV/Aids news stories. This study recommends that more attention should be given to upholding and respecting the rights of the affected and infected by the disease. The media should also allow their voices to be heard, not through spokespeople, but from their own mouths. / AFRIKAANSE OPSOMMING: Dit lyk of die media in sy voortgaande taak om Suid-Afrikaners in te lig en op te voed, die agenda op so ’n manier stel dat dit arm swart Afrikane as die enigste rassegroep voorstel wat deur MIV/Vigs geaffekteer en geïnfekteer word. Foto’s van arm swart Afrikane word ook gebruik om die publiek oor die pandemie in te lig en op te voed. In ’t kort, die media het ’n agenda gestel wat MIV/Vigs ’n swart, Afrika-gesig gee: een wat arm, ontvanklik en hulpeloos is, en wat in haglike toestande leef. Die hipotese van hierdie navorsing berus daarop dat dit rasse-stereotipiering is van arm swart Afrikane, en dat die Daily Dispatch en ander media dit perpetueer. Dit is ook belangrik om daarop te let dat die stemme van die geaffekteerde en geïnfekteerde nie so prominent in nuusberige oor die pandemie is nie. Hul stories word vertel deur die joernaliste self, of iemand anders wat ’n segspersoon is. Die media moet begin om hierdie helde en heldinne wat deur die siekte geaffekteer en geïnfekteer is, self hul storie te laat vertel, in hul eie woorde. Kwalitatiewe inhoudsanalise van die Daily Dispatch van 1 tot 31 Desember 2004 is uitgevoer. Nuusstories, foto’s, opskrifte en onderskrifte is geanaliseer. Hierdie analise toon dat die stemme van die geaffekteerde en geïnfekteerde steeds in ons nuusberigte ontbreek en dat arm swart Afrikane die enigste visuele onderwerpe in MIV-Vigs nuusstories is. Hierdie studie beveel aan dat meer aandag gegee moet word om die regte van die geaffekteerde en geïnfekteerde te bewaar en te respekteer. Die media moet ook toelaat dat diegene se stemme gehoor word, nie deur segspersone nie, maar uit hul eie monde. / ISISHWANKATHELOL: Kubonakala ngathi amajelo eendaba kwinzame zawo zokufundisa nokwazisa uluntu loMzantsi Afrika ngesifo sikaGawulayo neNtsholongwane yaso, abonakalisa abantu abaMnyama beli njengohlanga ekukuphela kwalo oluthi luchatshazelwe sesi sifo. Nkqu nemifanekiso ethi isetyenziswe kumabalili athetha ngesi sifo, yileyo yabantu abaMnyama abazimpula zikalujacu ezingathathi ntweni. Ngokufutshane amajelo eendaba anika isizwe umzobo osengqondweni othi, uGawulayo neNtsholongwane yakhe uchaphazela ze ubulale abantu abaMnyama abahluphekileyo nabaphila phantsi kweemeko zobugxwayiba. Kusenjalo olu hlalutyo lubonakalise ukuba amazwi abantu abanesifo sikaGawulayo nabo bachaphazelekayo awakho kupapasho lweendaba. Kwakhona iingxelo ngesi sifo zinika ingqwasela kubantu abaMnyama abahluphekileyo neminifanekiso yabo kuphela. Akukho nto ithethekayo ngezinye intlanga. Okokuqala, olu phando ngoko ke lucebisa ukuba makuhlonitshwe umGaqo Siseko weli ngokubhekiselele kumalungelo abantu ingakubi abo banesifo sikaGawulayo neNtsholongwane yaso. Okwesibini, amajelo eendaba mawaqinisekise ukuba abantu abagula sesi sifo nabo sibachaphazelayo bayazithethela ngemilomo yabo kuba ngabo abajamelene neentlungu umhla nezolo.

While the growing literature on South Africa’s healthcare and epidemics has often mentioned cholera in passing, there is as yet little academic work dedicated to it. This thesis addresses that deficit by examining the causes, spread and extent of cholera in South Africa between 1980 and 2003. Furthermore, it examines cholerarelated coverage in two newspapers, the Daily Dispatch and the Eastern Province Herald to determine how cholera and people with cholera were represented, and show how changes in the coverage of two major epidemics between 1980 and 2003 exemplify the political transition in South Africa, reflect changing political ideologies and reveal the shifting role of media within this period. The thesis argues three main points. Firstly, that representations of cholera and those who were sick with cholera were based on long-standing tropes connecting disease, class and ‘race’. Secondly, that policy-making based on these tropes influenced the unfair distribution and quality of health resources along racial lines, resulting in cholera outbreaks during the apartheid era. Failure to address these inequities post-apartheid, and the replacement of racial bias with discrimination on the grounds of socioeconomic development, resulted in further cholera outbreaks. Thirdly, using Alan Bell’s newspaper-discourse analysis framework to examine cholera-related articles the thesis compares and contrasts apartheid and postapartheid coverage in the two newspapers. This analysis reveals that during the 1980s the coverage was uncritical of the government’s handling of the epidemic or of its racially-discriminatory healthcare system. The newspapers uncritically accepted government-employed medical professionals as the final authorities on the epidemic, excluding alternative viewpoints. The coverage also “blamed the victim”, constructing affected “black” groups as potential threats to healthy “white” communities. Conversely, post–1994 coverage was criticised the government’s handling of the epidemic and the state of the public healthcare system. Government-employed medical professionals or spokespeople were not accepted as incontestable authorities and a range of sources were included. The coverage also shifted blame for the outbreaks to the government and its failure to address public health service delivery and rural development problems. The thesis shows the historical threat to the health of communities posed by uncaring governments.

Economic dispatch is an important optimization challenge in power systems. It helps to find the optimal output power of a number of generating units that satisfy the system load demand at the cheapest cost, considering equality and inequality constraints. Many nature inspired algorithms have been broadly applied to tackle it such as particle swarm optimization. In this dissertation, two improved particle swarm optimization techniques are proposed to solve economic dispatch problems. The first is a hybrid technique with Bat algorithm. Particle swarm optimization as the main optimizer integrates bat algorithm in order to boost its velocity and to adjust the improved solution. The second proposed approach is based on Cuckoo operations. Cuckoo search algorithm is a robust and powerful technique to solve optimization problems. The study investigates the effect of levy flight and random search operation in Cuckoo search in order to ameliorate the performance of the particle swarm optimization algorithm. The two improved particle swarm algorithms are firstly tested on a range of 10 standard benchmark functions and then applied to five different cases of economic dispatch problems comprising 6, 13, 15, 40 and 140 generating units. / Electrical and Mining Engineering / M. Tech. (Electrical Engineering)

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-02-11T12:29:20Z No. of bitstreams: 1 hevertonreissouza.pdf: 2039435 bytes, checksum: 82a19bf494e9ac400021280fb64ec1ae (MD5) / Rejected by Adriana Oliveira (adriana.oliveira@ufjf.edu.br), reason: Renata, bom dia! Por favor, confirme se não tem acento no Júnior: Silva Junior, Ivo Chaves da on 2016-02-26T11:58:58Z (GMT) / Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-02-26T12:02:02Z No. of bitstreams: 1 hevertonreissouza.pdf: 2039435 bytes, checksum: 82a19bf494e9ac400021280fb64ec1ae (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-03-03T13:38:08Z (GMT) No. of bitstreams: 1 hevertonreissouza.pdf: 2039435 bytes, checksum: 82a19bf494e9ac400021280fb64ec1ae (MD5) / Made available in DSpace on 2016-03-03T13:38:08Z (GMT). No. of bitstreams: 1 hevertonreissouza.pdf: 2039435 bytes, checksum: 82a19bf494e9ac400021280fb64ec1ae (MD5) Previous issue date: 2014-02-28 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O Sistema Interligado Nacional (SIN) possui características peculiares que o torna diferente de qualquer outro no mundo, como por exemplo, predominância de usinas hidrelétricas e uma extensa rede de transmissão. Estas características, aliadas a incerteza nas afluências futuras, conduz a necessidade da realização de vários estudos na área de planejamento da operação. O planejamento da operação energética tem por objetivo determinar metas de geração hidráulica e térmica, de forma a atender o mercado consumidor de energia, com confiabilidade e economicidade, utilizando da melhor forma possível os recursos energéticos disponíveis. Para este propósito são utilizados modelos matemáticos que buscam a minimização do custo total esperado de operação do sistema, dentro de um determinado horizonte de planejamento, utilizando diferentes níveis de detalhamento. O objetivo principal deste trabalho é avaliar alguns impactos da modelagem do sistema elétrico no problema de planejamento da operação de médio prazo. Neste sentido, o sistema de transmissão é representado em sua forma completa, através de equações não lineares que modelam os fluxos de potência ativa e reativa em cada circuito que compõe o sistema elétrico. Além disso, são considerados os limites de tensão nas barras, assim como o limite de carregamento dos circuitos para cada patamar de carga. As usinas hidrelétricas e termelétricas são representadas de forma individualizada, e a função de produtibilidade é modelada através de polinômios de quarto grau. O modelo proposto utiliza Funções de Custo Futuro (FCF) pré-calculadas por um programa de planejamento da operação de médio/longo prazo, baseado em sistemas equivalentes de energia. Neste trabalho foram utilizadas as FCF produzidas pelo programa Modelo de Despacho Hidrotérmico (MDDH), desenvolvido pela UFJF. Entretanto, é importante destacar que outro modelo de decisão estratégica, baseado em sistemas equivalentes de energia, poderia ser adotado para gerar as FCF utilizadas neste trabalho. A metodologia proposta neste trabalho foi avaliada através do estudo de casos tutoriais e de médio porte, objetivando demonstrar os impactos da representação do sistema de transmissão no custo total esperado de operação do sistema e diferenças na estratégia de operação do mesmo. / The Brazilian Interconnected System has unique characteristics that make it different of any other in the world, such as predominance of hydroelectric power plants and an extensive transmission system. These features, combined with uncertainty in future inflows, leads to necessity of conducting several studies on planning of the operation. The energy operation planning aims to determine targets for hydraulic and thermal generation to meet the consumer energy market with reliability and economy, as well as possible using the available energy resources. For this purpose mathematical models that aims to minimize the expected total cost of the system operation, within a given planning horizon, using different levels of detail are used. The main objective of this work is to evaluate some impacts of the transmission system modeling in the long-term operation planning problem. In this sense, the transmission system is included in its complete form, using nonlinear equations that model the active and reactive power flow in the electrical system. In addition, some operation limits are considered, such as bus voltage limits and power flow limits in the transmission lines and transformers, for each load level. The hydroelectric and thermoelectric plants are represented in an individual form and the producibility function is modeled by fourth degree polynomials. The proposed model uses cost-to-go functions calculated from a long term operation planning program based on equivalent energy systems. In this work the cost-to-go functions produced by MDDH program were used. This program was developed by the Federal University of Juiz de Fora (UFJF). However, it is important to point out that any other model of strategic decision, based on equivalent energy systems, could be used to generate the cost-to-go functions. The proposed methodology is evaluated and validated through the study of medium scale systems and tutorial systems. The main objective is to demonstrate the impact of the detailed transmission system modeling in the total system operating expected total cost and identify differences in operation strategy.

Submitted by Patrícia Cerveira (pcerveira1@gmail.com) on 2017-06-13T15:56:56Z No. of bitstreams: 1 Rene_Cruz_Freire.pdf: 5170376 bytes, checksum: 8c6b6dd8986d23b53ae99ba90dd69ef5 (MD5) / Approved for entry into archive by Biblioteca da Escola de Engenharia (bee@ndc.uff.br) on 2017-06-29T16:38:47Z (GMT) No. of bitstreams: 1 Rene_Cruz_Freire.pdf: 5170376 bytes, checksum: 8c6b6dd8986d23b53ae99ba90dd69ef5 (MD5) / Made available in DSpace on 2017-06-29T16:38:47Z (GMT). No. of bitstreams: 1 Rene_Cruz_Freire.pdf: 5170376 bytes, checksum: 8c6b6dd8986d23b53ae99ba90dd69ef5 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Um dos temas de alta relevância para a sociedade atual é a qualidade do suprimento de energia elétrica, que deve ser ininterrupto, seguro e econômico. Para tal, é primordial que o sistema de potência esteja preparado para um possível defeito de algum equipamento da rede, mantendo a operação dentro dos patamares seguros, evitando os blecautes e todas as suas consequências para a sociedade. Isso pode ser feito através do redespacho das unidades geradoras, de modo a encontrar um ponto de operação que concilie segurança e economicidade, dois objetivos conflitantes, enquanto busca se afastar o mínimo possível do ponto de operação previamente estabelecido, via planejamento eletroenergético, para o sistema de potência em questão. Trata-se de uma abordagem multiobjetiva do Fluxo de Potência Ótimo com Restrições de Segurança (FPORS) que pode ser solucionada com uma abordagem de Computação Evolucionária (CE) com viés multiobjetivo. Neste trabalho, foram implementadas e comparadas duas meta-heurísticas evolutivas multiobjetivo: Nondominated Sorting Genetic Algorithm II (NSGA-II) e o Multi-objective Evolutionary Particle Swarm Optimization (MOEPSO). Os resultados dessas heurísticas também foram comparados com a abordagem mono-objetivo do mesmo problema. Os algoritmos foram implementados no MATLAB® e testados em um sistema-teste que simula as condições do Sistema Interligado Nacional (SIN). As heurísticas multiobjetivo foram comparadas através da metodologia de análise da Fronteira de Pareto (FP), onde é analisado qual método concilia melhor os objetivos de economia e segurança. Na primeira análise o NSGA-II saiu-se melhor, entretanto após a implementação de melhorias no algoritmo, o MOEPSO mostrou desempenho superior na segunda análise. Nas duas análises, o viés multiobjetivo mostrou-se superior ao mono-objetivo, na comparação através do critério de agregação de objetivos. Em relação ao tempo de simulação de cada método, o MOEPSO foi superior na primeira análise, já na segunda análise foi implementado um refinamento baseado no Fluxo de Potência Linearizado no FPORS, que baixou o tempo de simulação das duas heurísticas multiobjetivas em comparação com a primeira análise, e o MOEPSO teve o menor tempo de simulação. Na comparação com o viés mono-objetivo, apenas o NSGA-II teve tempo médio de simulação maior que o método mono-objetivo na primeira análise. Na segunda análise, todas as heurísticas multiobjetivo possuíam tempo de simulação menores que o método mono-objetivo. / One of the topics of high relevance to the today’s society is the quality of electric power supply, which must be uninterrupted, safe and economical. To this end, it is essential that the power system be prepared for a possible defect of some equipment from the network while maintaining operation within safe levels, avoiding blackouts and all its consequences for society. This can be done by redispatch of generating units, in order to find an operation point which conciliate security and economy, two conflicting objectives, while seeking to depart as little as possible of the operation point previously established in the energy planning for the power system in question. This is a multi-objective approach to Security Constrained Optimal Power Flow (SCOPF) that can be solved with an approach of Evolutionary Computation with multi-objective bias. In this work we were implemented and compared two multi-objective evolutionary meta-heuristics: Nondominated Sorting Genetic Algorithm II (NSGA-II) and Multi-objective Evolutionary Particle Swarm Optimization (MOEPSO). The results of these heuristics were also compared with mono-objective approach to the same problem. The algorithms were implemented in MATLAB® and tested in a test-case that simulates the conditions of the Brazilian Sistema Interligado Nacional (National Interconnected System). The multi-objective heuristics were compared using the analysis methodology of the Pareto Frontier, where is analyzed which method is better to conciliate the economy and security objectives. In the first analysis the NSGA-II fared better, but after the implementation of improvements in the algorithm, the MOEPSO showed superior performance in the second analisys. In both analyzes, the multi-objective bias was superior to the mono-objective bias, in the comparison through objectives aggregation criteria. Concerning the simulation time of each method, the MOEPSO was superior in the first analysis, but in the second analysis was implemented a refinement based on DC Load Flow, which lowered the simulation time of the two multi-objective heuristics compared with the first analysis, and the MOEPSO had the shortest time simulation. Compared to the mono-objective bias, only the NSGA-II had an average time simulation greater than the mono-objective method in the first analysis. In the second analysis, all multi-objectives heuristics had simulation time smaller than the mono-objective method.

La presente investigación denominada “Propuesta de reducción del costo de despacho de cereales a granel” tiene el objetivo de determinar una propuesta de reducción del costo de despacho de cereales a granel de la empresa objeto de estudio. Se realizó un estudio de causa - efecto, análisis de datos cuantitativos y observaciones instantáneas para identificar la actividad donde se tiene un sobre costo en el servicio de despacho. Identificando como problemas los altos costos que significan las actividades de liberación de paneles y barredura de silos metálicos que se realizan de manera manual. Se presentó el estudio económico de dos propuestas de solución, de las cuales se optó que la mejor propuesta tiene una inversión que asciende a S/.232,700.49 nuevos soles; el cual será asumido al 100% por la misma empresa. La evaluación económica muestra un Valor Actual Neto (VAN) mayor a cero y una Tasa Interna de Retorno (TIR) mayor al costo de oportunidad del accionista por lo que se concluye que el proyecto genera valor y es económicamente viable, al implementar dicha propuesta las actividades de liberación de paneles y barredura de silos metálicos se realizaran de manera semiautomática. This research entitled "Proposal for reducing the cost of bulk grain exports" aims to determine a method for reducing the cost of bulk grain dispatch of the company under study. A cause and effect study was conducted using quantitative analysis of data and instant feedback to identify where the activity has a cost overrun on the dispatch service. As problems identifying significant than the high costs brought Activities Liberation panels and metal silo sweep carried out manually. An economic study of two proposed solutions, of which it was decided that the best proposal is an investment amounting to S/. 232,700.49 was presented; which shall be provided 100% by the same company. The economic assessment shows a higher Net Present Value (NPV) of zero and a Internal Rate of Return (IRR) greater than the opportunity cost of shareholders. Therefore, it is concluded that the project creates value and is economically feasible to implement this proposal, the proposal to implement activities and sweep release panels were held metal silo semi-automatically.

The UK’s decarbonisation strategy to increasingly electrify heating and transport will change the demand requirement on the electricity system. Additionally, under a climate change future, it is projected that the decarbonised grid will need to be able to operate under higher average temperatures in the UK, increasing the need for comfort cooling during summer and leading to additional electricity demand. These new demands will result in greater variation between minimum and peak demand as well as a significant increase in overall demand. Concurrently, supply-side decarbonisation programmes may lead to more intermittent renewables such as wind, PV, tidal and wave, elevating variability in electricity generation. Coupled with the anticipated higher variation in demand this brings on several challenges in operating the electricity grid. In order to characterise these challenges this research develops a bespoke electricity dispatch model which builds on hourly models of demand and generation. The hourly demand profiles are based on a high electrification of heating, transport and cooling coupled with future temperatures premised on the UKCP09 high emission scenario climate projections. The demand profiles show a significant increase in peak demand by 2050 reaching 194 GW, mainly due to summer cooling loads which contribute 70% of the demand. The cumulative CO2 emissions budgets of the GB power sector that are consistent with avoiding global climate change to 2°C are used to develop two low carbon generation scenarios distinguished by the amount of intermittent renewable generation technologies. The dispatch model tests the capability of generation scenarios with the use of hourly generation models in meeting future demand profiles out to 2050.The outputs from dispatch model indicate that there are shortages and excesses of generation relative to demand from 2030 onwards. The variability analysis outlines low and high generation periods from intermittent technologies along with the pace at which intermittent generation increases or decreases within an hour. The characterisation of variability analysis reveals the type of reserve capacity or smart solutions that are required to maintain the security of electricity supply. The solutions that could address the challenges quantified from the model outputs in operating a decarbonised GB electricity grid are explored using expert interviews. The analysis of the stakeholder interviews suggests smart grid solutions that include technologies as well as changes in operational procedures in order to enhance the operational resilience of the grid. Active Network Management through monitoring and control, demand management, storage systems and interconnectors are proposed to address challenges arising from varying demand and generation variability.

This thesis deals with application of optimisation methods based on linear and mixed-integer linear programming to various problems in the power sector related to electricity production. The thesis goal is to test the applicability of such methods to formulating and solving various instances from the class of real-world electricity production problems, and to find the advantages and disadvantages associated with using these methods. Introductory chapters describe the main characteristics of power markets, including the historical and regulatory context. Fundamental properties of power markets on both demand and supply side are also described, both from a real-world and a modelling point of view. Benefits of optimisation and modelling are discussed, in particular the solution feasibility and optimality as well as insights gained from sensitivity analysis which is often difficult to replicate with the original system. In the core of the thesis, optimisation techniques are applied to three case studies, each of which deals with a specific problem arising during electricity production. In the first problem, the profit of gas-fired power plant in Slovakia from selling power on the day-ahead market is maximised. The model is set up using both technical and commercial constraints. The second problem deals with the problem of representing a two-dimensional production function which primarily arises for a hydro generator with large variations in the level of its reservoir. Several representations of the original function using piecewise linear subsets are presented, compared, and characterised by their computational intensity both theoretically and practically. In the third problem, the prices on the German day-ahead market in 2011 are modelled. Contrary to the previous two models, the model does not capture an optimisation problem faced by a single producer, but incorporates a large subset of the whole market instead. Consequently the model is formed out of generic constraints relevant to all power plants whose parameters are estimated. By combining information about the aggregate availability of power plants with the estimated efficiencies a full supply curve for each day is created. Different scenarios are analysed to test the impact of uncertain inputs such as unknown or estimated constraints. The choice of the investigated problems stems from the attempt to cover electricity production problems from the point of view of multiple criteria. The three investigated electricity production problems span a broad range from the decisions of a single power plant to the modelling a power market as a whole. Formulations of the production function with different level of detail are presented ranging from a simple linear relationship to several bivariate function formulations. While each problem answers a specific question, they all illustrate the ease with which various electricity production problems can solved using optimisation methods based on linear and mixed-integer linear programming. This is mainly due to the ability of these methods to approximate even non-linear functions and constraints over non-convex domains and find global solutions in reasonable time. Moreover, models formulated with these methods allow sensitivity and scenario analyses to be carried out easily as is illustrated in each of the case studies.

Orientador: Prof. Dr. Thales Souza / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Elétrica, Santo André, 2018. / Atualmente, no Brasil, a matriz elétrica é composta predominantemente por fonte hidráulica e térmica, na proporção de 70% e 30%, respectivamente. Nesse sentido, para a segurança do Sistema Interligado Nacional, o mesmo é considerado um sistema hidrotérmico, onde a disponibilidade de armazenamento das bacias hidráulicas e de combustíveis representa a quantidade de energia elétrica disponível para atendimento a demanda. Assim, os critérios para cálculo de Energia Assegurada representam as Garantias Físicas das Usinas Hidrelétricas e Usinas Térmicas, que são calculadas através das médias de gerações dos empreendimentos disponíveis no Sistema Interligado Nacional com a previsão de 15 anos. Contudo, a expansão dos aproveitamentos de usinas com reservatório encontra-se no limite de exploração no sul e sudeste/centro-oeste, havendo apenas na região Norte potenciais a serem avaliados. Entretanto, devido às restrições ambientais, não há previsão de construção de novas Usinas Hidrelétricas com reservatório na região Norte, o que indica a necessidade de viabilização de outras fontes de energia elétrica. Nesse sentido, a Garantia Física é utilizada para balizar qual o risco de déficit futuro considerando o balanço de demanda e oferta no sistema. Dessa forma, o presente trabalho propôs a análise dos parâmetros de risco da Garantia Física do sistema imputados no modelo de projeção elétrico NEWAVE. Por fim, com objetivo de validar a análise proposta, as projeções de Garantias Físicas das Usinas Hidrelétricas e Usinas Térmicas que fazem parte do Sistema Interligado Nacional foram avaliadas, a partir do método de escolha do risco de déficit. / Currently, in Brazil, the electrical matrix is mainly composed of hydraulic and thermal sources, in the proportion of 70% and 30%, respectively. In this sense, for the safety of the National Interconnected System, it is considered a hydrothermal system, in which the storage capability of the hydraulic basins and fuel availability represent the amount of electrical energy available to meet demand. Thus, the criteria for calculation of Assured Energy represent the Physical Guarantees of the Hydroelectrical Power Plant and Thermal Power Plants, which are calculated through the average of generations of the enterprises available in the National Interconnected System with a forecast of 15 years. However, the expansion of uses of power plants with reservoirs is at the exploration limit in the South, Southeast/Center-West, with only the North region with potential to be evaluated. Still, due to environmental restrictions, there is no prevision of construction of new Hydroelectrical Power Plant with reservoir in the North region. Being so, the Physical Guarantee is used to identify the future deficit risk by making a balance of supply and demand in the system. In this way, the present work proposed an analyze of Physical Guarantee system risk parameters imputed in the electrical projection model NEWAVE. So, to validate the methodology proposed the Physical Guarantee projection of the Hydroelectrical Power Plant and Thermal Power Plants that are part of the National Interconnected System were evaluated consdering the method of choosing the risk of deficit.

O trabalho apresenta uma discussão sobre o nível de contratação ótima dos geradores hidroelétricos participantes do Mecanismo de Realocação de Energia (MRE), considerando a influência dos Procedimentos Operativos de Curto Prazo (POCP). O assim denominado POCP é um conjunto de procedimentos realizados pelo Operador Nacional do Sistema (ONS) para proporcionar mais segurança no atendimento à carga do Sistema Interligado, sendo realizado no período de abril a novembro, durante o Programa Mensal de Operação (PMO). O gerador hidráulico, em função do despacho centralizado e normativo adotado no Brasil, dependendo da quantidade de água que aflui aos reservatórios e do consequente despacho das usinas determinado pelo ONS, fica sujeito às exposições no mercado de curto prazo, decorrentes da diferença entre os contratos de venda do gerador e o montante de garantia física (GF) alocada mensalmente após a realização do MRE. Como o POCP não está incorporado nos modelos de despacho das usinas do setor elétrico, uma alternativa de simulação foi construída e, a partir dos seus resultados, pode-se perceber a interferência do mecanismo em tela nas exposições no mercado de curto prazo e no patamar de risco incorrido. A aplicação do POCP traz um efeito líquido de redução da geração hidrelétrica, pois se diminui a possibilidade de utilizar a capacidade de regularização dos reservatórios, evitando riscos de eventual não recuperação dos reservatórios no período chuvoso. Por outro lado, o procedimento conservador hoje utilizado pode gerar um volume muito maior de vertimentos durante o período úmido, limitando a chance de recuperação financeira dos geradores hidrelétricos que tiveram sua geração reduzida no período seco devido ao despacho antecipado de termelétricas, fatalmente com rebatimentos traduzidos por exposições ao PLD. Por conta de todos os fatores de risco citados, os agentes geradores precisam ajustar sua estratégia ótima de contratação, mantendo a função objetivo de maximizar a receita, condicionado a critérios de risco, que ponderem os fatores citados. Nessa perspectiva, foi analisada a aplicação do POCP no ano de 2010 e seus impactos, além de simular a receita esperada e o risco futuro com e sem a aplicação deste mecanismo. Os resultados mostram o quanto o POCP interfere na receita esperada dos agentes, agregando maiores riscos e alterando-se o nível de contratação ótima. Sendo assim, dependendo do risco que cada agente gerador está disposto a assumir, uma revisão de seu nível de contratação torna-se imperiosa. / This work presents a discussion about the optimal level of energy contracting of the Hydroelectric Generators participants of the Energy Reallocation Mechanism, (MRE - Mecanismo de Realocação de Energia), considering the influence of Short Term Operating Procedures (POCP - Procedimentos Operativos de Curto Prazo). The POCP is a set of procedures performed by the National System Operator (ONS - Operador Nacional do Sistema) to provide more security in the Interconnected System, being carried out from April to November, during the Monthly Programme Operation (PMO - Programa Mensal de Operação). Hydro plants are subject to exposure in short-term market due to the centralized dispatch adopted in Brazil, which depends on the amount of water that flows to the reservoir and on the subsequent dispatch of plants determined by the ONS. The exposure in short-term market, arises from the difference between the Generator sales contracts and the amount of assured energy (GF - Garantia Física) monthly allocated after the MRE. As the POCP is not incorporated into the dispatch models of the electricity sector, an alternative simulation was built and, from its results, we can notice the interference of the mechanism displayed in the short-term market and in the incurred risk level. The application of the POCP brings a net reduction in hydropower generation, because it decreases the possibility of using the regularization capacity of the reservoirs, avoiding any risk of non recovery of the reservoirs during the rainy season. On the other hand, the conservative procedure used today can generate a much larger volume of spilling water during the wet season, limiting the chance of financial recovery of hydroelectric dams that had their generation reduced in the dry season due to the anticipated dispatch of thermoelectric plants, inevitably with repercussions represented by exposure to the PLD (SPOT). Considering all risk factors mentioned, the generating agents have to adjust their optimal strategy for contract level, retaining the objective function to maximize revenue, conditional to risk criteria, which consider the factors mentioned. From this perspective, we analyzed the application of the POCP in 2010 and its impacts, as well as simulated the expected revenue and the future risk with and without the application of this procedure. The results show how the POCP interferes in the expected revenue of the agents, adding greater risks and changing the optimal level of energy contracting. Thus, depending on the risk that each generating agent is willing to take, a review of their contracting level becomes imperative.