This report documents an MSc Thesis work of sub-transmission reliability study using PSS/Eperformed at Vattenfall. The network that is examined in this thesis is a sub-transmission network.Vattenfall Distribution Sweden is going to invest and rebuild the network in their 70 and 130 kVmeshed sub transmission network. To invest and rebuild in a network is very expensive. The gridowners want a reliable system that has a high reliability at a low cost.The main focus in this thesis is to examine different substation layouts. Calculating the failureintensities and unavailability for the different substation layouts gives the opportunity to do a life cyclecosts (LCC) on the different substations. With help of LCC calculations it is possible to find thesubstation that gives the lowest cost during a life time. Choosing right equipment in the grid will helpthe Vattenfall network company lower their equipment costs.The thesis work consists of mainly three parts as follows. Network modeling in PSS/EA subset of the existing sub transmission network was used in the project. This subset was taken outfrom the complete network model and modeled in PSS/E. Validation of PSS/E reliability modulesPSS/E reliability modules were new and have not been used earlier by the Vattenfall networkcompany. To be sure that the program calculates correctly a validation was performed. The main focusof the validation has been in looking if the program calculates the interrupted power correctly. Reliability analysis of different substation layoutsFor each of the substation layout the reliability was calculated. On component level (e.g. breaker,disconnector) different types of configuration were studied. To find out the best layout from aneconomical point of view a LCC calculation was also performed.The LCC calculation on the different substation layouts showed that the investment costs affect theresult very much. When the active power through the substation is low it is preferred to use asubstation that has low investment costs. At active power that is 30 MW or higher it is preferred to usethe substation with higher reliability (having higher investment cost). The result shows that using acombined breaker and disconnector instead of circuit breaker could lower the failure intensity andunavailability of substations.

During the past decade, renewable energy sources have become an indispensable pillar in European electricity generation. This paper aims at examining if the increasing importance of renewables stimulates investment in European power transmission networks. The question of interest is addressed by an error correction investment model that builds on Neoclassical theory and is further augmented by recent literary findings. Under the proposed threefold estimation strategy, the share of renewables is not found to significantly influence investment spending when the full set of transmission system operators are considered. However, a slight and justified sample restriction leads to the conclusion that a rising share of renewable energy sources substantially increases investment in power transmission networks. / Series: Department of Economics Working Paper Series

Offshore wind power is attracting increasing levels of research and investment. The use of HVDC transmission and the development of DC grids are topics with similar high levels of interest that go hand in hand with the development of large scale, far from shore wind farms. Despite increased capital cost of some components, DC power transmission can have significant advantages over AC transmission, in particular in the offshore environment. These advantages are well established for large scale, long distance point to point transmission. This thesis assesses the suitability of a multi-terminal DC power collection network, with short cables and relatively small amounts of power, addresses a number of the technical challenges in realising such a network and shows methods for overall system cost reduction. Technical and modelling challenges result from the interaction between power electronic DC-DC converters and the cables in a DC transmission network. In particular, the propagation of the ripple current in bipole DC transmission cables constructed with a metallic sheath and armour is examined in detail. The finite element method is used to predict the response of the cable to the ripple current produced by the converters. These results are used along with wave propagation theory to demonstrate that cable design plays a crucial role in the behaviour of the DC system. The frequency dependent cable models are then integrated with time domain DC-DC converter models. The work in the thesis is, broadly, in two parts. First, it is demonstrated that care and accuracy are required in modelling the cables in the DC transmission system and appropriate models are implemented and validated. Second, these models are combined with DC-DC converter models and used to demonstrate the practicality of the DC grid, make design recommendations and assess its suitability when compared with alternative approaches (e.g. AC collection and/or transmission).

Submitted by Maria Aparecida (cidazen@gmail.com) on 2017-08-02T13:58:14Z No. of bitstreams: 1 Dissertacao Claudio.pdf: 6336618 bytes, checksum: c06faa9f49cc4b573db64e75da62a327 (MD5) / Made available in DSpace on 2017-08-02T13:58:14Z (GMT). No. of bitstreams: 1 Dissertacao Claudio.pdf: 6336618 bytes, checksum: c06faa9f49cc4b573db64e75da62a327 (MD5) Previous issue date: 2013-03-27 / CNPQ / After implantation of the new economic model for power systems, a fair remuneration strategy of transmission companies has become a matter of great importance. This remuneration should be performed by system users, who must pay proportionally to its network usage. However, there is still no consensus about wich is the best criterion to be adopted to allocate these costs. The most widely used methods take into account the power ows only at normal operating conditions. however, it is recognized that the transmission system is planned and operated to accommodate power also at contingency scenarios, which requires additional transmission capacity. Moreover, part of the idle capacity is due to the characteristics of network investments and uncertainty in relation to demand. Thus, the costs allocated by these methods may not re ect the actual usage of the system. In this context, this work presents a transmission cost allocation method that takes into consideration all these network characteristics. The total costs are decomposed into three components, each of these associated with a part of the transmission capacity of the system and its function. These costs are then allocated based on their system usage in diferent operating scenarios. To validate the proposed method, tests are performed on small and medium power systems. Comparisons are established with some methods more used in the literature, where it is observed that the proposed method provides complete consistency with the expected results for the problem. It was also found that this method offers subsidies to consumers allowing them to define their security requirements. / Com a implantação do novo modelo econômico nos sistemas de potência, a adequada remuneração das empresas provedoras de serviços de transmissão tem se tornado um assunto de grande importância. Esta remuneração deve ser realizada pelos usuários do sistema, que devem pagar proporcionalmente ao seu grau de utilização da rede. No entanto, ainda não há um consenso do melhor critério a ser adotado para alocar estes custos. Os métodos mais utilizados levam em consideração os uxos de potência apenas quando a rede opera em condições normais. No entanto, sabe-se que o sistema de transmissão é planejado e operado para acomodar os uxos também em cenários de contingência, o que exige capacidade adicional de transmissão. Além disso, parte da capacidade ociosa é devido às características dos investimentos no setor e à incerteza em relação à demanda. Desta forma, os custos alocados por estes métodos pode não re etir a real utilização do sistema. Neste contexto, este trabalho apresenta um método de alocação dos custos pelo uso da transmissão que leva em consideração todas estas características da rede. Os custos totais são decompostos em três componentes, cada uma destas relacionada com parte da capacidade de transmissão do sistema e sua função. Estes custos são então alocados aos usuários da rede com base no seu grau de utilização do sistema em diversos cenários de operação. Para validar o método proposto, são realizados testes em sistemas de potência de pequeno e médio porte. Comparações são estabelecidas com alguns dos métodos mais aplicados na literatura, onde constata-se que o método proposto apresenta total coerência com os resultados esperados pelo problema. Veri ca-se ainda que este método oferece subsídios aos consumidores para que estes possam de nir quais seus requisitos de segurança.

A epidemia de HIV-1 está mudando em São Paulo, com uma crescente preocupação no número de jovens de homens que fazem sexo com homens (HSH). A epidemia é dominada pelos subtipos B, F1, porém tem aumentado a prevalência do subtipo C. O objetivo do estudo foi identificar e caracterizar as redes de transmissão em São Paulo, comparando entre os subtipos epidêmicos, fatores de risco e exposição à terapia antirretroviral. Nós compilamos dados clínicos, epidemiológicos e as sequencias virais dos indivíduos acompanhados no Instituto Adolfo Lutz de Jan 2004 a fev de 2015. Após o controle de qualidade, 2.260 sequencias parciais do gene pol foram subtipadas previamente como B, C e F1 e então incluídas no estudo. 2.107 sequencias únicas controle foram selecionadas pelo blast contra as nossas sequencias no banco de dados de Los Alamos e banco de dados de Portugal. Todas as sequencias foram investigadas para a identificação de mutação de resistência (TDRM). Árvores filogenéticas foram construídas em RaxML para cada subtipo. Nós usamos Cluster Picker para analise da dinâmica de transmissão de acordo com os parâmetros de distância genética e bootstrap. Análises estatísticas foram utilizadas para identificar possíveis correlações dos clusters. 414 (18,3%) da nossa população foi incluída em cluster (2-12 indivíduos). A taxa de cluster não diferiu entre B e F1, no entanto as sequencias do subtipo C se agruparam duas vezes mais (p<0.001). Mais clusters foram identificados entre a população HSH quando comparada a de heterossexuais independente do subtipo (p<0.001). A taxa de TDRM foi maior em cluster que fora de cluster nos subtipos B e F1 (p<0.001 e p=0.009), respectivamente. Apesar do alto número de clusters no subtipo C verificamos baixa prevalência de TDRM. Os indivíduos que estavam em clusters eram 5 anos mais jovens que os de fora de cluster nos subtipos B e C (p<0.001 e 0.02, respectivamente). Nossos resultados indicam que, independente do subtipo, a epidemia de HIV-1 em São Paulo é auto-sustentada pelos pacientes HSH virgens de tratamento. O subtipo C apresentou maior proporção de clusters. No entanto, mais análises são necessárias para clarificar se isto implica em alta taxa de transmissão do subtipo em São Paulo. / The HIV-1 epidemic in Sao Paulo is changing, with a worrying increase in the number of new infections in young men and in the Men who have Sex with Men (MSM). The epidemic is dominated by subtypes B and F1, but theres been a recent increase in the prevalence of subtype C. The aim of this study was to identify and characterize HIV-1 transmission networks in Sao Paulo, comparing across subtype epidemics, risk factors, and HAART exposure therapy. We gathered epidemiological, clinical and viral sequence data from HIV-1 infected individuals followed in Adolfo Lutz Institute/SP-BR from Jan 2004 through Feb 2015. After quality control, 2,260 sequences of the partial pol gene were subtyped as previously reported as B, C and F1 were included on this study. 2,107 unique background control sequences were selected by blasting our sequences against Los Alamos database and the Portuguese HIV-1 database. The dataset was screened for Drug Resistance Mutations to identify transmitted drug resistance mutations (TDRM). Maximum-Likelihood phylogenetic trees were built in RaxML for each subtype separately. We used Cluster Picker to analyze transmission dynamics according the thresholds: genetic distance (0.06) and bootstrap over 90%. Statistical analyzes were performed to identify possible correlates of clustering. Categorical variables were compared using Chi-square or Fishers exact test and quantitative variables were analyzed using Mann-Whitney test (SPSS). 414 (18,3%) of our population were included in clusters (range: 2-12 individuals). The rate of clustering did not differ between subtypes B and F, however more subtype C sequences (40%) significantly clustered together (p<0.001). Furthermore, more clusters were significantly found in the MSM group when compared to heterosexuals for all subtypes, (p<0.001). Also, drug naïve patients were more likely to be in clusters when compared to treated patients in all subtypes (p <0.001). TDRM were more prevalent in clustering than in non-clustering in subtypes B (p <0.001) and F1 (p =0.009), and more related to MSM group. Despite the higher number of clusters, subtype C presented a lower prevalence of TDRM, although without significant difference between cluster and non-cluster. Clustering individuals were also 5 years younger than non-clustering individuals for subtypes B and C (p<0.001 and 0.02, respectively). Our results indicate that, regardless of subtype, the HIV-1 epidemic in Sao Paulo is self-sustained by treatment-naive MSM patients, who transmit the infection before starting treatment. Subtype C presents a higher proportion of patients that cluster together. However, further analyses are necessary to clarify whether this implies a higher transmission rate of this subtype in Sao Paulo.

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (p. 132-136).

This research focuses on improving the efficiency of power market operations by providing system operators additional tools for managing the costs of supplying and delivering electricity. A transmission topology control (TC) framework for production cost reduction based on a shift factor (SF) representation of branch and breaker flows is proposed. The framework models topology changes endogenously while maintaining linearity in the overall Mixed Integer Linear Programming (MILP) formulation. This work develops the DC lossless, and loss-adjusted TC formulations that can be used in a Day Ahead or intra-day market framework as well as an AC-based model that can be used in operational settings. Practical implementation choices for the Shift Factor formulation are discussed as well as the locational marginal prices (LMPs) under the TC MIP setting and their relation to LMPs without TC. Compared to the standard B-theta alternative used so far in TC research, the shift factor framework has significant computational complexity advantages, particularly when a tractably small switchable set is optimized under a representative set of contingency constraints. These claims are supported and elaborated by numerical results.

Made available in DSpace on 2016-08-17T14:53:13Z (GMT). No. of bitstreams: 1 Jacob de Melo Cruz.pdf: 515166 bytes, checksum: 2bda304fdbb90f8e9e02395f91554a0a (MD5) Previous issue date: 2010-08-19 / The active and reactive power services and transmission losses allocation methods had became an important issue after implantation of power systems new economic model and with open market access to agents (generators and loads) due the increase global power demand. The objective is to solve the problem of power services and transmission losses allocations and finding services beneficiaries as well transmission losses responsibilities to each market agents of a fair and equitable way. The results of the allocation problem are very important to economics evaluations of investments in futures generations and loads units installations. Several allocation methods has been proposed in the specialized technical literature, however due the non-linear characteristic of transmission losses and loads, there isn t an ideal method, and still remains the equity question. This work is intented to propose a method to simultaneously allocations performing active and reactive power service and transmission active and reactive losses. The method is based on circuit laws and superposition principle. The method suggest a modeling of sources and loads as equivalent admitances and taking into account the similarities, based on electric circuits, of power services and transmission losses allocations. The proposed method uses a load flow results and divide network into operation scenarios and generators and loads are modeling as equivalent admittances and the current injections are null and then the network is represented by branches and active and reactive power generated or consumed are determined and allocating among market agents. Finally, analysis, simulations and comparisons with some methods proposed in literature are performed, using four buses test system and IEEE 30 buses. / Os métodos de alocação de serviços de potência ativa e reativa e das perdas de transmissão ativa e reativa têm recebido cada vez mais atenção após a reestruturação do setor elétrico, que promoveu livre acesso a diversos agentes (geradores e cargas), e com a crescente demanda de energia pela economia global. O principal objetivo dos métodos de alocação é determinar a participação dos agentes de uma forma justa e equilibrada nos serviços de potência e nas perdas de transmissão. A alocação é muito importante na avaliação econômica de investimentos para as localizações de novas instalações de unidades de geração e consumo. Diversos métodos para resolução do problema de alocação têm sido propostos na literatura técnica especializada, contudo, devido à natureza não-linear das perdas, não existe um método aceito como ideal. Neste trabalho, é proposto um método de alocação simultânea dos serviços de potência ativa e reativa e das perdas de transmissão ativa e reativa, baseada nas leis de circuitos e no princípio da superposição. A motivação desta proposta está no fato que, do ponto de vista de circuitos elétricos, esses processos de alocação têm tratamento similar. A diferença surge posteriormente, no momento da interpretação dos resultados obtidos. O método se baseia no resultado do fluxo de carga e divide o problema em cenários de operação, modelando os geradores e cargas como admitâncias equivalentes um de cada vez. Em seguida, a rede é representada por ramos e as potências ativa e reativa geradas ou consumidas são determinadas e alocadas aos agentes. Finalmente, são realizadas simulações, análises e comparações com alguns métodos propostos usando um sistema teste de 4 barras e o sistema IEEE 30 barras.

Includes bibliographical references / Many large, sparsely distributed raptors are threatened by a host of anthropogenic factors, while a minority may actually benefit from some aspects of development and environmental change. Clarity on the size and trajectory of such populations is essential for effective conservation management, but can be difficult to achieve. One solution is to use multivariate habitat association models to derive critical estimates of distribution and abundance. The South African population of Martial Eagle Polemaetus bellicosus is currently estimated at < 800 adult birds , with the bulk of the known population believed to be residing in the larger protected areas. However, Martial Eagles also build nests on pylons that support high voltage transmission lines running through the largely treeless, semiarid landscapes of the Karoo. The main aim of this study was to develop a better understanding of the environmental factors that influence Martial Eagle territory densities and locations along South African transmission lines, and thereby estimate the size of this population and its relative importance to the national conservation status of this globally threatened species. I used habitat association models to d escribe Martial Eagle territory density in relation to eight environmental covariates. Models were first fitted to eagle territory data for the central Karoo regions, collected and pooled over the period 2002 - 2006, and then applied to predict the number of pairs present on each of three adjacent sections of unsurveyed line (northern, southern and eastern lines) . Once these model predictions were verified by a series of aerial and ground surveys, I fitted the models to all the known Martial Eagle territory records for the transmission network and extrapolated from these back to the rest of the network using the fitted relationships. Ultimately, the models predicted 52 additional Martial Eagle territories on the remaining transmission network with a confidence interval ranging from 38 to 67 (based on models that explained up to 39 % of the total variance in terms of only two explanatory terms – rainfall and the proportion of cultivated land). I then examined the role of territoriality and social structure in the eagle population in determining the location and dispersion of pylon nests. To do this I used the location of active nests from the original central Karoo data and a similar number of randomly selected points. I then asked whether I could predict the nest locations from each of the eight environmental covariates and distance to its nearest conspecific active nest or its nearest nest of any other large eagle species. Using a logistic generalised linear model with regression splines for distance to nearest other nest, I found that Martial Eagles strongly avoid proximity to conspecific nests (mean distance to conspecific nest = 28.2 km, range 2.5 - 167.1 km, n = 306). This result shows that minimum spacing should be considered in predicting the distribution of eagles on unsurveyed transmission lines. Lastly, I further investigated the geographical extent of pylon nesting in South African Martial Eagles, with particular focus on variation in the frequency of this behaviour in relation to biome - scale variation in the availability of trees as natural nest sites. To do this, I related Martial Eagle reporting rates generated by citizen - science bird atlas data to the density of transmission lines and biome types across South Africa. While these analyses yielded some suggestive results, such as significant positive and negative relationships between reporting rates and line density in the Desert (P = 0.02) versus the Savanna (P < 0.001) biomes respectively, data sparseness in arid areas and a generally low detection probability limited the conclusiveness of these results. The refined habitat association models developed in this study predict that the South African transmission grid supports 130 - 159 breeding pairs of Martial Eagle. This figure has never been estimated or calculated before, and suggests that 36 % of the national breeding population could reside largely in the commercial ranchland and nest on man - made structures. This result, which is at odds with the generally held belief that the Martial Eagle is increasingly confined to large protected areas, has significant implications for the thinking around the conservation management of this globally threatened species.

An important issue in today's power system is the need to analyse and determine the adequacy of transmission capacity. There is a need for approaches to increase transmission system capacity without construction of new transmission facilities, all while assuring secure operation of the grid. New technologies can enhance efficiency and reliability, increase capacity utilization, enable more rapid response to contingencies, and increase flexibility in controlling power flows on transmission lines. Distributed Series Reactor (DSR) control is a new smart grid technology that can be applied to control flows in the transmission system. DSRs can be used to balance phase flows in a single line as well as to control the distribution of flow in parallel flow paths. This dissertation investigates the Design of Distributed Series Reactors (DSRs) on transmission lines and provide guidelines and considerations for their implementation in bulk power system transmission networks to control power flow to: increase the exisiting transmission capacity utilization, alleviate overloads due to load growth and contingencies, and mitigate the effects of unbalanced voltages, unbalanced transmission line impedances and unbalanced loads by balancing flows in the phases of an unbalanced line. This dissertation provides several DSR System Design aspects; for a single line by performing an experiment for EHV and high voltage three parallel transmission lines, and for lines within the boundaries of a power system by deployment of DSRs over the IEEE 39 bus system that is modified and modelled as a 3-phase unbalanced transmission model with 345 kV lines that accounts for tower geometry and as a balanced, 3-phase model that is derived from the unbalanced, 3-phase model, and finally for lines within a control area and a set of tie lines among control areas by deployment of DSRs over a real system control area and the tie lines connecting this area to other power pool areas. For all experiments and simulations in this dissertation lines are modelled as 3-phase lines. The DSR system design for Unbalanced vs. Balanced 3-phase systems (Unbalanced immittance, Unbalanced load) are examined. Also the Distributed vs. Lumped models for 3-phase systems are tested. Comparison between DSR system design and transposition for voltage balancing was performed. The effect of bundling the conductors for DSR system design was investiagted. In this dissertation an economic evaluation of DSR System Design for parallel lines and for the IEEE 39 bus three-phase unbalanced line model for N-1 criterion contingency with load growth is performed. The economic evaluation performed for the DSR system design of a power system versus new transmission line construction showed that DSRs can be cost effective in managing load increases from year to a year, and thus avoid larger investments in new line construction until load expectations are proven to be true. Thus, a major value of DSRs is handling load growth in the short term, delaying larger investments. Although many aspects of DSR control implementation have yet to be explored, this work has demonstrated the fundamental concept is sound and the economics are compelling. / Ph. D.