Environmental concerns and long term energy security are the key drivers behind most current electric energy policies whose primary aim is to achieve a sustainable, reliable and affordable energy system. In a bid to achieve these aims many changes have been taking place in most power systems such as emergence of new low carbon generation technologies, structural changes of power system and introduction of competition and choice in electricity supply. As a result of these changes, the level of uncertainties is growing especially on generation side where the locations and available capacities of the future generators are not quite clear-cut. The transmission network needs to be flexibly and economically robust against all these uncertainties. The traditional operation of the network under preventive control mode is an inflexible practice which increases the total system cost. Corrective control operation strategy, however, can be alternatively used to boost the flexibility, to expedite the integration of the new generators and to decrease the overall cost. In this thesis, the main focus is on development of new techniques and methodologies that can be used for modelling and solving a transmission planning problem under the assumption that post-contingency corrective actions are plausible. Three different corrective actions, namely substation switching, demand response and generation re-dispatch are investigated in this thesis. An innovative multi-layer procedure deploying a genetic algorithm is proposed to calculate the required transmission capacity while substation switching is deployed correctively to eradicate the post-fault network violations. By using the proposed approach, a numerical study shows that the network investment reduces by 6.36% in the IEEE 24 bus test system. In another original study, generation re-dispatch corrective action is incorporated into the transmission planning problem. The ramp-rate constraints of generators are taken into account so that the network may be overloaded up to its short-term thermal rating while the generation re-dispatch action is undertaken. The results show that the required network investment for the modified IEEE 24 bus test system can be reduced by 23.8% if post-fault generation re-dispatch is deployed. Furthermore, a new recursive algorithm is proposed to study the effect of price responsive demands and peak-shifting on transmission planning. The results of a study case show that 7.8% of total investment can be deferred. In an additional study on demand response, a new probabilistic approach is introduced for transmission planning in a system where direct load curtailment can be used for either balancing mechanism or alleviating the network violations. In addition, the effect of uncertainties such as wind power fluctuation and CO2 emission price volatility are taken into account by using Monte Carlo simulation and Hypercube sampling techniques. Last but not least, a probabilistic model for dynamic thermal ratings of transmission lines is proposed, using past meteorological data. The seasonal correlations between wind power and thermal ratings are also calculated. £26.7 M is the expected annual benefit by using dynamic thermal ratings of part of National Grid's transmission network.

Energy sector transformation is of interest to policy makers and energy researchers. Critical to this transformation is efficient (i.e. least-cost) infrastructure investment planning for new generation and transmission infrastructure investments. Similarly, energy policies designed to encourage low carbon electricity generation have fueled much of the transformation globally over the past two decades. However, knowledge gaps remain with respect to the unique economic and geographic features of Small Island Developing States (SIDS); recommendations from previous studies often have limited applicability to the SIDS context. This dissertation addresses these concerns, contributing to our understanding of least-cost planning methods for new infrastructure investments as well as energy policies appropriate for small, isolated and often heavily indebted nations. The island of Jamaica is used as a case study to gain insights more applicable to the broader SIDS context.<div><br></div><div>The first problem this dissertation addresses is the impact of simultaneously planning for generation and transmission infrastructure instead of sequentially optimizing these decisions, as is commonly done. Energy infrastructure planning in SIDS treats transmission infrastructure as an afterthought once generation investments have been determined, potentially leading to sub-optimal investments. Using a dynamic optimization model of generation and transmission infrastructure, we find that it is more cost effective to co-optimize generation and transmission investments. The substitutability between local generation and remote generation, facilitated by transmission infrastructure, underpins this result. <br></div><div><br></div><div>The second empirical problem we address is the impact of loop flow on optimal infrastructure investment decisions. The Energy Information Agency (EIA) defines loop flow as “the movement of electric power from generator to load by dividing along multiple parallel paths; it especially refers to power flow along an unintended path that loops away from the most direct geographic path or contract path” (EIA, n.d.). We find no evidence that loop flow affects optimal investment decisions in Jamaica. We attribute this to an abundance of transmission capacity and the relative simplicity of Jamaica’s network design. Results may differ for other SIDS with different starting configurations.<br></div><div><br></div><div>The third problem this dissertation addresses centers on energy policy. We quantify the cost to the Jamaican society under four different policy scenarios: a renewable portfolio standard (RPS) of 30% by year 2030, a carbon tax, a production tax credit and an investment subsidy for specific renewable energy resources (solar and wind). We find that if the decision makers’ primary concern is reducing carbon emissions, a carbon tax is the economically efficient choice (of the four options); an RPS has the second-lowest cost to society. Assessing the tradeoffs associated with each option, a carbon tax is efficient but increases the average annual cost of electricity. If, however, the decision makers’ primary objective is energy independence and not carbon emissions reduction, then the RPS may be a better alternative than a carbon tax.<br></div><div><br></div><div>Collectively, this dissertation demonstrates a method for improving long-term planning in the electricity sector in SIDS. It also quantifies the cost to society of implementing a menu of carbon mitigating policies, removing the ambiguity that persists in energy policy setting. Not only does this dissertation advance the energy economic literature by specifically addressing the economic and geographic features of SIDS, but we make our data and program files freely accessible. This is one measure that helps to overcome the data limitation hurdle that is a main contributor to the dearth of energy economics research more applicable to SIDS.<br></div>

Ao buscar alternativas para interligação entre importantes centros de geração de energia elétrica localizados no Norte do Brasil e centros consumidores no Nordeste e Sudeste, o setor elétrico brasileiro se depara com o desafio de transpor distâncias superiores a 2000 km. A alternativa em corrente contínua já é bastante utilizada, com desempenho satisfatório. Já a transmissão em meia-onda, ainda não utilizada comercialmente em país algum do mundo, é uma alternativa sugerida por alguns artigos como adequada a esse propósito. Este trabalho se propõe a apresentar uma metodologia de comparação econômica entre alternativas de transmissão e aplicá-la à comparação entre a meia-onda e a corrente contínua, utilizando um cenário muito próximo ao brasileiro. Para possibilitar esta comparação, são apresentados detalhes do funcionamento da linha de meia-onda, já que pouco foi publicado sobre o assunto. São mencionados alguns aspectos adversos de seu comportamento transitório e também são descritas etapas de definição de alternativas de transmissão a serem avaliadas. / In order to connect important power generation plants located in Northern region to the major load centers in the Northeast and Southeast parts of the country, the Brazilian electric sector should deal with the challenge of planning transmission systems to cover distances of more than 2000 km. The HVDC transmission alternative, which has shown satisfactory response and performance to also carry bulk power over long distances, is already used in many countries. Still, the half-wavelength power transmission line (HWLL), not yet commercially used in any country, is an alternative suggested by some papers as suitable for this purpose. Thus, the objective of this work is to present a methodology for the economic comparison amongst the transmission alternatives present today, to thereafter apply it to the HWLL and HVDC transmission technologies. To do so, a closest scenario to that of the Brazilian case will be used. In order to perform this comparison, some details of the HWLL operation are explored, since little was published on this subject. Also, some adverse aspects of the HWLL transient behavior as well as the steps for defining the transmission alternatives to be evaluated are presented.

Ao buscar alternativas para interligação entre importantes centros de geração de energia elétrica localizados no Norte do Brasil e centros consumidores no Nordeste e Sudeste, o setor elétrico brasileiro se depara com o desafio de transpor distâncias superiores a 2000 km. A alternativa em corrente contínua já é bastante utilizada, com desempenho satisfatório. Já a transmissão em meia-onda, ainda não utilizada comercialmente em país algum do mundo, é uma alternativa sugerida por alguns artigos como adequada a esse propósito. Este trabalho se propõe a apresentar uma metodologia de comparação econômica entre alternativas de transmissão e aplicá-la à comparação entre a meia-onda e a corrente contínua, utilizando um cenário muito próximo ao brasileiro. Para possibilitar esta comparação, são apresentados detalhes do funcionamento da linha de meia-onda, já que pouco foi publicado sobre o assunto. São mencionados alguns aspectos adversos de seu comportamento transitório e também são descritas etapas de definição de alternativas de transmissão a serem avaliadas. / In order to connect important power generation plants located in Northern region to the major load centers in the Northeast and Southeast parts of the country, the Brazilian electric sector should deal with the challenge of planning transmission systems to cover distances of more than 2000 km. The HVDC transmission alternative, which has shown satisfactory response and performance to also carry bulk power over long distances, is already used in many countries. Still, the half-wavelength power transmission line (HWLL), not yet commercially used in any country, is an alternative suggested by some papers as suitable for this purpose. Thus, the objective of this work is to present a methodology for the economic comparison amongst the transmission alternatives present today, to thereafter apply it to the HWLL and HVDC transmission technologies. To do so, a closest scenario to that of the Brazilian case will be used. In order to perform this comparison, some details of the HWLL operation are explored, since little was published on this subject. Also, some adverse aspects of the HWLL transient behavior as well as the steps for defining the transmission alternatives to be evaluated are presented.

Orientador: Ariovaldo Verandio Garcia, Ruben Augusto Romero Lazaro / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-06T06:56:43Z (GMT). No. of bitstreams: 1 RiderFlores_MarcosJulio_D.pdf: 1021887 bytes, checksum: 6000961c2f5457b410ac691912476270 (MD5) Previous issue date: 2006 / Resumo: Neste trabalho são propostos modelos matemáticos e técnicas de solução para resolver o problema de planejamento da expansão de sistemas de transmissão através de três enfoques. a) Usando o modelo de corrente alternada do sistema de transmissão e um algoritmo heurístico construtivo especializado para resolver o problema de planejamento, e, ainda, realiza-se uma primeira tentativa de alocação de fontes de potência reativas; b) Usando o modelo de corrente contínua e técnicas de programação não-linear especializadas. Nesse caso emprega-se uma versão relaxada do problema de planejamento da expansão de sistemas de transmissão usando o modelo de corrente contínua, onde a integralidade das variáveis de investimento é desprezada. Resolve-se o problema de programação não-linear, modelado de forma matricial com um algoritmo de otimização especializado e, além disso, um algoritmo heurístico construtivo especializado é utilizado para resolver o problema de planejamento. c) Usando o modelo de corrente contínua e um algoritmo Branch and Bound (B&B) sem empregar técnicas de decomposição. Para isso foram redefinidos os chamados testes de sondagem no algoritmo B&B e em cada nó da árvore de B&B tem-se um problema de programação não-linear que são resolvidos usando a metodologia desenvolvida no item (b). Os ítens (a), (b) e (c) requerem a solução de problemas de programação não-linear diferenciados. Uma revisão das características principais da resolução iterativa dos métodos de pontos interiores é apresentada. Foi desenvolvida uma técnica baseada em uma combinação de métodos de pontos interiores de alta ordem (MPI-AO) para resolver os problemas de programação não-linear de forma rápida, eficiente e robusta. Essa combinação dos MPI-AO tem como objetivo colocar num único método as características particulares de cada um dos MPI-AO e melhorar o desempenho computacional comparado com os MPI-AO de forma individual / Abstract: In this work mathematical models and solution techniques are proposed to solve the power system transmission expansion planning problem through three approaches: a) Using the nonlinear model ofthe transmission system (AC model) and a specialized constructive heuristic algorithm to solve the problem and, yet, a first attempt to allocate reactive power sources is also considered; b) Using the direct-current (DC) model and specialized techniques of nonlinear programming. In this case a version of the power system transmission expansion planning problem using the DC model where the integrality of the investment variables is relaxed is used. The nonlinear programming problem is solved with a specialized optimization algorithm and, moreover, a constructive heuristic algorithm is employed to solve the planning problem. c) Using the DC model and Branch and Bound (B&B) algorithm without the use of decomposition techniques. The so called fathoming tests of the B&B were redefined and at each node of the tree a nonlinear programming problem is solved using the method developed in b). Items a), b) and c) require the solution of distinct problems of nonlinear programming. A revision of the main characteristics of the iterative solution of the interior points methods is presented. An optimization technique based on a combination of the higher order interior point methods (HO-IPM) had been developed to solve the nonlinear programming problems in a fast, efficient and robust way. This combination of the HO-IPM has as objective to explore the particular characteristics of each method in a single one and to improve the comparative computational performance with the HO-IPM of individual form / Doutorado / Energia Eletrica / Doutor em Engenharia Elétrica

Power flow (PF) control can increase the utilization of the transmission system and connect lower cost generation with load. While PF controllers have demonstrated the ability to realize dynamic PF control for more than 25 years, PF control has been sparsely implemented. This research re-examines PF control in light of the recent development of fractionally-rated PF controllers and the incremental power flow (IPF) control concept. IPF control is the transfer of an incremental quantity of power from a specified source bus to specified destination bus along a specified path without influencing power flows on circuits outside of the path. The objectives of the research are to develop power system operation and planning methods compatible with IPF control, test the technical viability of IPF control, develop transmission planning frameworks leveraging PF and IPF control, develop power system operation and planning tools compatible with PF control, and quantify the impacts of PF and IPF control on multi-decade transmission planning. The results suggest that planning and operation of the power system are feasible with PF controllers and may lead to cost savings. The proposed planning frameworks may incent transmission investment and be compatible with the existing transmission planning process. If the results of the planning tool demonstration scale to the national level, the annual savings in electricity expenditures would be $13 billion per year (2010$). The proposed incremental packetized energy concept may facilitate a reduction in the environmental impact of energy consumption and lead to additional cost savings.