A microgrid is a subnetwork of power system that consists of a group of distributed energy sources and loads. It is designed to integrate distributed generation, loads, energy storage devices, converters, and monitoring and protection devices. Generally, a successful microgrid could run both in island mode (off-grid) and in grid-connected mode (on-grid), being able to convert between two modes at any time. With continuous development of the power system, distributed renewable generation unit accounts for an increasing proportion, since microgrid could effectively connect these generation units to the main grid, thereby improving the energy efficiency and the energy structure. Microgrid is increasingly playing an important role in the power system. This thesis focuses on reducing the cost of microgrids through economic operation, including both static and dynamic economic operations. Three cases are tested based on these two methods. Also, each case will include four situations including one without ESS and three situations with 2MWh ESS, 3MWh ESS, 4MWh ESS, respectively.

Asset management and automation are acknowledged by distribution utilities as a useful strategy to improve service quality and reliability. However, the major challenge faced by decision makers in distribution utilities is how to achieve long-term return on the projects while minimising investment and operation costs. Distribution automation (DA) in terms of transformer economic operation (TEO), distribution network reconfiguration (DNR), and sectionalising switch placement (SSP) is recognised as the most effective way for distribution network operators (DNOs) to increase operation efficiency and reliability. Automated tie-switches and sectionalising switches play a fundamental role in distribution networks. A method based on the Monte Carlo simulation is discussed for transformer loss reduction, which comprises of profile generators of residential demand and a distribution network model. The ant colony optimisation (ACO) algorithm is then developed for optimal DNR and TEO to minimise network loss. An ACO algorithm based on a fuzzy multi-objective approach is proposed to solve SSP problem, which considers reliability indices and switch costs. Finally, a multi-objective ant colony optimisation (MOACO) and an artificial immune systems-ant colony optimisation (AIS-ACO) algorithm are developed to solve the reconfiguration problem, which is formulated within a multi-objective framework using the concept of Pareto optimality. The performance of the optimisation techniques has been assessed and illustrated by various case studies on three distribution networks. The obtained optimum network configurations indicate the effectiveness of the proposed methods for optimal DA.

Os institutos jurídicos têm estreita relação com sua base econômica. Nos contratos de seguro essa afirmação é de fundamental importância, sendo o contrato a face jurídica de uma complexa operação econômica. O desenvolvimento do instituto levou ao reconhecimento da essencialidade da empresarialidade do seguro. Há acentuada controvérsia na doutrina acerca da natureza comutativa ou aleatória do contrato de seguro. O ponto central desta dissertação é no sentido de que o Código Civil de 2002 adotou a garantia como a prestação principal do segurador, o que importa no reconhecimento de sua natureza comutativa. O mesmo Código reconheceu a empresarialidade como elemento essencial do contrato. A comutatividade permite o exame das obrigações e deveres a cargo das partes num contexto de equilíbrio. O trabalho finalmente propõe que a interpretação e aplicação do contrato de seguro observem o caráter comutativo e a base técnica do negócio. / Legal institutions have a close relationship with their economic fundaments. In the insurance contract, this statement is of great importance as it is the legal face of a complex economic operation. The development of the institution has led to the acknowledgment of the entrepreneurial side of the insurance as an essential attribute of the contract. There is a strong dispute on the nature of the contract, if it is an aleatory contract or a certain contract. The main point of this essay is in the sense that the Civil Code of 2002 has adopted the guarantee as the main obligation of the insurer, which represents the acknowledgement of its nature of a certain contract. This nature of the contract permits the examination of the obligations and duties of the parties in a context of equilibrium. The essay finally proposes that the interpretation and construction of the insurance contract observe both the character of a certain contract and its technical fundaments.

Os institutos jurídicos têm estreita relação com sua base econômica. Nos contratos de seguro essa afirmação é de fundamental importância, sendo o contrato a face jurídica de uma complexa operação econômica. O desenvolvimento do instituto levou ao reconhecimento da essencialidade da empresarialidade do seguro. Há acentuada controvérsia na doutrina acerca da natureza comutativa ou aleatória do contrato de seguro. O ponto central desta dissertação é no sentido de que o Código Civil de 2002 adotou a garantia como a prestação principal do segurador, o que importa no reconhecimento de sua natureza comutativa. O mesmo Código reconheceu a empresarialidade como elemento essencial do contrato. A comutatividade permite o exame das obrigações e deveres a cargo das partes num contexto de equilíbrio. O trabalho finalmente propõe que a interpretação e aplicação do contrato de seguro observem o caráter comutativo e a base técnica do negócio. / Legal institutions have a close relationship with their economic fundaments. In the insurance contract, this statement is of great importance as it is the legal face of a complex economic operation. The development of the institution has led to the acknowledgment of the entrepreneurial side of the insurance as an essential attribute of the contract. There is a strong dispute on the nature of the contract, if it is an aleatory contract or a certain contract. The main point of this essay is in the sense that the Civil Code of 2002 has adopted the guarantee as the main obligation of the insurer, which represents the acknowledgement of its nature of a certain contract. This nature of the contract permits the examination of the obligations and duties of the parties in a context of equilibrium. The essay finally proposes that the interpretation and construction of the insurance contract observe both the character of a certain contract and its technical fundaments.

Made available in DSpace on 2016-08-17T14:53:12Z (GMT). No. of bitstreams: 1 Romel Jimenez.pdf: 804071 bytes, checksum: 8f161d1f48519af0d6ee9068f4876a93 (MD5) Previous issue date: 2007-02-26 / In this work a methodology based on linear programming for long-term hydrothermal scheduling of electric power systems is proposed. The objective of the hydrothermal scheduling is to find an optimal operation for a specific time interval and with high reliability and minimum cost. That is equivalent to determine an optimal generation scheduling for the power plants and for each time interval considered, in order to the power system satisfies the forecasted demand. Linear models of the power system components are adopted, and with the option to solve systems with multiple reservoirs and buses. It was implemented a computer program using MATLAB platform for application to small test power systems and configurations of real-size systems such as the interconnected Peruvian System and the Brazilian South-Souheast System. For the solution of the linear optimization problem was used the interior points method. From the analysis of the test systems results is concluded that the linear model may capture adequately the relevant characteristics of the real power system and it may be eficient and precise such as the detailed model. / Neste trabalho é proposta uma metodologia baseada em programação linear para a solução da coordenação hidrotérmica de longo prazo de sistemas de energia elétrica. O objetivo da coordenação hidrotérmica é encontrar uma política de operação ótima em um determinado período de tempo, com alta confiabilidade e custo mínimo. Isto equivale a determinar um cronograma ótimo de geração para cada usina, a cada intervalo de tempo, de modo que o sistema atenda a demanda prevista. Adotam-se modelos lineares dos componentes do sistema de potência, com a opção de resolver sistemas com múltiplos reservatórios e múltiplas barras. Foi implementado um programa computacional em MATLAB para a solução de sistemas teste de pequeno porte e configurações de sistemas de potência reais tal como o Sistema Interligado Peruano e o Sistema Brasileiro da Bacia Sul-Sudeste. Para a solução do problema de otimização linear foi utilizado o método de pontos interiores. Da análise dos resultados com os sistemas teste conclui-se que o modelo linear pode capturar adequadamente as características relevantes do sistema real e pode ser tão eficiente e preciso quanto o modelo detalhado.

Σκοπός αυτής της Διπλωματικής είναι η μελέτη του προβλήματος οικονομικής κατανομής φορτίου και η μελέτη του προβλήματος ένταξης μονάδων ενός καθαρά θερμικού συστήματος. Το πρόβλημα της οικονομικής κατανομής φορτίου και της ένταξης μονάδων εξετάζονται αρχικά θεωρητικά. Στα πλαίσια αυτής της Διπλωματικής γίνεται και εφαρμογή της οικονομικής κατανομής φορτίου και της ένταξης μονάδων σ' ένα ενδεικτικό δίκτυο δοκιμών με χρήση Η/Υ. Για την οικονομική κατανομή φορτίου χρησιμοποιείται το πρόγραμμα Economic Dispatch Program και για την ένταξη μονάδων, τα προγράμματα Unit Commitment και Unitcom. Επίσης εξετάζεται συνοπτικά το Ελληνικό σύστημα ηλεκτρικής ενέργειας και δίνονται τα βασικά σημεία της Απελευθέρωσης Αγοράς Ηλεκτρικής Ενέργειας στην Ελλάδα. / This diploma essay's purpose is to study the economic dispatch problem and the unit commitment problem of a simple thermal power system. Initially, the economic dispatch problem and the unit commitment problem are examined theoretically. In this essay takes place an application of the economic dispatch problem and an application of the unit commitment problem, in an indicative test network, with the use of a PC. For the economic dispatch problem is used the Economic Dispatch Program and for the unit commitment problem are used the Unit Commitment and Unitcom programs. Furthermore, in this essay are concisely examined the Hellenic power system and the release of the Hellenic electric market.