Controlling the power flow in transmission systems has recently gained increased interest. The difficulties of building new lines and the pressure of having a high utilization of existing assets, makes the flexibility of grid systems increasingly important. This master thesis work investigates induction regulators as control devices for active power flow in a transmission system. A small change in angle of the rotor affects both the amplitude and the phase of the voltage. The magnetic coupling in the induction regulator can be controlled by changing the permeability of a thermo magnetic material such as gadolinium and can hence give a second independent controlling parameter. An analytical model and calculations in the FEM software AceTripleC together with Matlab, is used to simulate the influence of the regulators connected to a simple grid in case1, a 400 kV scenario and case 2, a 45 kV scenario. The analysis was carried out on a small transmission system consisting of two parallel transmission lines connected to source and load. The induction regulators are connected to one of the parallel transmission lines. The regulators modelled in case 1 must be able to control the active power flow in the regulated line to vary between 50 and 150 % of the original power flow through this line. This shall be done over a range of 0 to 800 MW transmitted power. The regulators modelled in case 2 must be able to control the active power flow in the regulated line to vary between 0 and 30 MW, if this does not cause the power flow in the parallel line to exceed 30 MW. This shall be done over a range of 0 to 50 MW transmitted power. The regulators are designed as small and inexpensive as possible while still fulfilling requirements regarding the active power flow controllability in the grid, current density in windings and maximum flux density in core and gap. The results indicate that the size of the 400 kV solution has to be reduced to become competitive whereas for the 45 kV solution the relative difference to existing solution is smaller. Advantages with the proposed design over a phase shifting transformer are mainly a simpler winding scheme and the absence of a tap changer.

With the deregulation of power industry and the market competition, low cost, reliable power supply, and secured system operations are major concerns of the advanced deregulation markets. It is a natural extension to revise the objectives of the traditional optimal power flow (OPF) to help dispatch the power. Maximizing social welfare to create more values of the market is becoming an interesting topic. In the deregulation environment, a user-friendly mechanism is desirable to form an auction market information framework (AMIF) for power auction and market operation. This thesis proposed a prototype system to combine internet based technology, database system, and the auction market to construct an information framework of power auction market. The Internet technology used Dynamic HTML (DHTML) in WWW website to develop a convenient bidding environment for users. The database based on MS Access used open database connection (ODBC) technology to connect database and internet. The auction market integrates auction functions and re-designed OPF to support the auction mechanism and congestion management. This research could also provide a solid foundation for Taiwan¡¦s power system deregulation in the future. The proposed mechanism and its expansion could guarantee a smooth migration process and successful market/system operation.

The objective of this thesis is to determine a method for computing the amount of capacitance in a power electronic converter required to melt a fuse in the event of a line to ground fault. DC micro-grids rely on power electronic converters to change voltage levels. All converters rely on semiconductor switches that must be protected from surges of fault current. This limits the power that a converter can supply to a fuse. In many cases, sufficient power may be achieved by appropriately sizing the converters’ output capacitor. / text

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[pt] Este trabalho apresenta uma metodologia e correspondente programa computacional para o planejamento da expansão de uma rede distribuição que permite determinar, por exemplo, a localização de banco de capacitores e de reguladores de tensão e/ou auto-boosters, o ganho de tensão e redução de perdas elétricas com a troca de condutores. A metodologia proposta é baseada na solução do problema de fluxo de potência desenvolvido especificamente para a distribuição. O trabalho automatiza procedimentos rotineiros do planejamento dos sistemas de distribuição, aumentando sua eficiência na análise correta de alternativas, auxiliando o planejador na tomada de decisões para determinar a expansão dos sistemas de distribuição. Testes com sistema da COELBA são apresentados. / [en] This work presentes a methodology and a digital computer program for the expansion planning of a distribuition network that allows to determine, for exemple, the location of capacitors bank and voltage regulators and/or automatic-boosters, voltage gain and redution of electrical losses with the changing of conductors. The proposed methodology is based on the solution of the power flow problem developd espcifically to distribution systems. The work automatizes common procedures for distribuition systems planing, increasing its efficiency in choosing correct alternatives, aidding the planer to make decisions to determine the distribution systems expansion. Several tests with COELBA system s are presented.

[pt] Este trabalho apresenta uma metodologia para o cálculo de Fluxo de Potência em redes radiais através do Método de Soma de Potências, que explora as características dos parâmetros da rede bem como a sua topologia, constituindo- se em um método bastante rápido e robusto. Propõe-se também uma nova metodologia para o controle de tensão na rede através de rotinas de sensibilidade visando a efetuação de manobras ou cortes de carga na rede. São apresentados testes com sistemas realistas. / [en] This work presents a methodology for radial power flows based on the power Summation Method, able to exploit the network particular characteristics in order to achieve accuracy and efficiency. This work also presents a novel model for radial network control based on sensitivity coefficients that evaluate load transfer or curtailment effects on network performance. Some tests with realistic systems are presented.

[pt] O fluxo de potência probabilístico é considerado uma técnica eficiente na obtenção de índices de segurança, tais como: a probabilidade de sobrecarga nas linhas de transmissão, probabilística de sobretensão em barramentos, etc., os quais são medidas extremamente úteis no planejamento e na operação de sistemas de potência. Este índices são obtidos dada a capacidade de tal algoritmo considerar a natureza probabilística das cargas em uma única solução. Nesta tese, a dependência entre as potências nodais é modelada de forma a considerar fatores ambientais e sociais como também o critério de pré-despacho usado no balanço da potência ativa do sistema. Estes aspectos são então incluídos no fluxo de potência probabilístico e o novo algoritmo é testado com dois sistemas de potência. O novo algoritmo de fluxo de potência probabilístico considerando dependências entre as potências nodais proposto por esta tese pode ser visto como uma técnica bastante realística para avaliar os riscos de insegurança dos sistemas de potência. / [en] Probabilistic load flow can be considered an efficient technique in order to essess security índices, such as: the probability of a line being greater than its thermal rating, probability of a busbar voltage being outside its operational constraints, etc., which are extremely useful measurements in planning and operation of power systems. These indices are schieved due to the capability of such algorithm in recognising the probabilistic nature of generation and load within one solution. In this thesis, the dependence between nodal powers is modelled in order to account environmental and social factors and the unit commitment criteria used to balance the system active power. These aspects are then included in the conventional probabilistic load flow and the new algorithm is tested with two power systems. The new probabilistic load flow algorithm considering dependence between nodal powers proposed by this thesis can be seen as very realistic technique to evaluate system security risks.

[pt] Este trabalho apresenta uma metodologia para a consideração das restrições de segurança no modelo de Análise de Confiabilidade Composta de Sistemas de Potência, obtendo índices que permitem avaliar a segurança da operação do sistema. A metodologia proposta é baseada na identificação das restrições críticas do sistema e relaxação das restrições não críticas durante a solução do problema de Fluxo de Potência Ótimo. São apresentados testes com sistemas realistas. / [en] This work presents a methodology for considering security constraints in Power Systems Composite Reliability Evaluation obtaining índices to evaluate system operation security. The proposed approach is based on the identification of system critical constraints and relaxation of non-critical constraints in the solution of the Optimal Power Flow problem. Some tests with realistic systems are presented.

abstract: In recent years, with the increasing penetration of solar generation, the uncertainty and variability of the power system generation also have increased. Power systems always require a balance between generation and load. The generation of the conventional generators must be scheduled to meet the total net load of the system with the variability and uncertainty of the solar resources integrated. The ability to match generation to load requires certain flexibility of the conventional generation units as well as a flexible transmission network to deliver the power. In this work, given the generation flexibility primarily reflected in the ramping rates, as well as the minimum and maximum output of the generation units, the transmission network flexibility is assessed using the metric developed in this work. The main topic of this thesis is the examination of the transmission system flexibility using time series power flows (TSPFs). First, a TSPFs program is developed considering the economic dispatch of all the generating stations, as well as the available ramping rate of each generating unit. The time series power flow spans a period of 24 hours with 5-minute time interval and hence includes 288 power flow snapshots. Every power flow snapshot is created based on the power system topology and the previous system state. These power flow snapshots are referred to as the base case power flow below. Sensitivity analysis is then conducted by using the TSPFs program as a primary tool, by fixing all but one of the system changes which include: solar penetration, wires to wires interconnection, expected retirements of coal units and expected participation in the energy imbalance market. The impact of each individual change can be evaluated by the metric developed in the following chapters. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2019

[pt] Após a análise de inúmeras deficiências inerentes à formulação clássica do problema do fluxo de carga, apresentou-se uma formulação mais ampla que, entretanto, implica na resolução de um sistema não linear de desigualdades. Esse, é tratado à luz de programação não linear e resolvido através da combinação do Método das penalidades com Métodos quase-Newtonianos, dando-se especial atenção ao de Davidon-Fletcher-Powell. Constatada a viabilidade de implementação em tempo hábil desse procedimento, estendeu-se a aplicação à outros problemas de análise de sistemas de potência; alocação ótima de potência reativa, minimização de perdas, dando-se ênfase ao primeiro. Inúmeros testes com sistemas de diversas configurações e dimensões entre 5 e 57 barras, foram realizadas com ótimos resultados computacionais (tempo de processamento e qualidade da solução obtida). Concluiu-se que a metodologia apresentada pode servir como valioso instrumento na área de análise de sistemas de potência. Em particular, constou-se a viabilidade de utilização para o controle On Line da Operação. / [en] After the analysis of numerous deficiencies inherent in the classical formulation of the load flow problem, a more general formulation is presented. Howerer, this formulation requires the solution of a non-linear system of inequalities. These, treated in the non-linear programming framework, are solved by a combination of Penalty and Quasi-Newton Optimization Methods, special attention being given to the Davidon-Fletcher-Powell approach. Having verified the applicability of the procedure to such problem, the application was extended to other problems in the analysis of power systems: optimum allocation of reactive power, minimization of losses, with special attention given to the first. Many tests on systems of diverse configuration and, with dimensions varying from 5 to 57 bars, were realized. Excellent results were obtained, with respect to processing time and the quality of the solutions. It is concluded that the method presented can serve as a valuable tool in the area of power system analysis and in particular, for the On-Line control of the Operation.