Decentralized AC power flow for real-time multi-TSO power system operation

This paper adjusts decentralized OPF optimization to the AC power flow problem in power systems with interconnected areas operated by diferent transmission system operators (TSO). The proposed methodology allows finding the operation point of a particular area without explicit knowledge of network data of the other interconnected areas, being only necessary to exchange border information related to the tie-lines between areas. The methodology is based on the decomposition of the first-order optimality conditions of the AC power flow, which is formulated as a nonlinear programming problem. To allow better visualization of the concept of independent operation of each TSO, an artificial neural network have been used for computing border information of the interconnected TSOs. A multi-area Power Flow tool can be seen as a basic building block able to address a large number of problems under a multi-TSO competitive market philosophy. The IEEE RTS-96 power system is used in order to show the operation and effectiveness of the decentralized AC Power Flow. ©2010 IEEE.

Terapêutica com doses profiláticas de sulfato ferroso como medida de intervenção no combate à carência de ferro em crianças atendidas em unidades básicas de saúde

Objetivou-se testar a terapêutica com doses profiláticas de sulfato ferroso no combate à anemia carencial ferropriva, em 620 crianças de 4 a 36 meses de idade, atendidas em duas unidades de saúde do Município de São Paulo, Brasil. As crianças foram submetidas a coleta de sangue para dosagem de hemoglobina. em seguida, foi prescrito dosagem de 12 mg/dia de ferro elementar, por 30 dias. Observou-se que 25% dos menores de 6 meses apresentaram níveis de hemoglobina inferiores a 11,0 g/dl. As maiores ocorrências de anemia foram detectadas entre os 9 e 23 meses de idade (50,0%). Decorrido o prazo, apenas 37,4% das crianças com anemia e 52,4% das não anêmicas retornaram para reavaliação. Das 299 que foram reavaliadas, somente 157 (52,5%) receberam a medicação corretamente. A freqüência de hemoglobinas inferiores a 9,5 g/dl caiu de 17,1% no início, para 8,1% ao final da intervenção. Por outro lado, o percentual de crianças com hemoglobinas superiores a 12,0 g/dl subiu de 13,4%, para 33,4%. As que receberam a suplementação férrica de forma correta registraram queda nos índices de anemia sensivelmente maior que a observada naquelas suplementadas de forma incorreta. Concluiu-se que a terapêutica com doses profiláticas de sulfato ferroso, apesar de se mostrar eficiente na recuperação dos níveis de hemoglobina, apresenta sérios entraves do ponto de vista operacional.

An approach of optimal sensitivity applied in the tertiary loop of the automatic generation control

This paper proposes an approach of optimal sensitivity applied in the tertiary loop of the automatic generation control. The approach is based on the theorem of non-linear perturbation. From an optimal operation point obtained by an optimal power flow a new optimal operation point is directly determined after a perturbation, i.e., without the necessity of an iterative process. This new optimal operation point satisfies the constraints of the problem for small perturbation in the loads. The participation factors and the voltage set point of the automatic voltage regulators (AVR) of the generators are determined by the technique of optimal sensitivity, considering the effects of the active power losses minimization and the network constraints. The participation factors and voltage set point of the generators are supplied directly to a computational program of dynamic simulation of the automatic generation control, named by power sensitivity mode. Test results are presented to show the good performance of this approach. (C) 2008 Elsevier B.V. All rights reserved.

An evaporative and desiccant cooling system for air conditioning in humid climates

Evaporative cooling operates using water and air as working fluids. It consists in water evaporation, through the passage of an airflow, thus decreasing the air temperature. This system has a great potential to provide thermal comfort in places where air humidity is low, being, however, less efficient where air humidity is high. A way to solve this problem is to use dehumidifiers to pre-conditioning the process air. This paper presents a system that can be used in humid climates coupling desiccant dehumidification equipment to evaporative coolers. The paper shows, initially, the main characteristics of the evaporative cooling and of the adsorption dehumidification systems. Later on the coupled systems, in which occurs a dehumidification by adsorption in a counter flow rotary heat exchanger following the evaporate cooling of the air in evaporative coolers, are analyzed. The thermodynamic equations of state are also presented. Following, this paper analyzes some operation parameters such as: reactivation temperature, R/P relationship (reactivation air flow/ process air flow) and the thermodynamic conditions of the entering air flow. The paper shows the conditions for the best operation point, with regard to thermal comfort conditions and to the energy used in the process. In addition this paper presents an application of the system in different climate characteristics of several tropical and equatorial cities. Copyright © 2005 by ABCM.

Optimization of multipulse converters with delta and Y-differential connections

This work presents a study regarding the optimization of multipulse converters. A general expression for the connection (Δ or Y) for both 12 and 18-pulses is obtained and describes the output voltages on the secondary windings, depending on the voltage reference from the primary. These generalized expressions allows choosing different ratios between input and output voltages and as result an optimum operation point for the converter can be calculated. Considering Δ-connected converters the optimum point occurs when the magnetic core of the autotransformer processes 18% and 17% of the output power for 12 and 18-pulses, respectively. For Y-connected converters the optimum point occurs when the kVA rating is 13% and 18% for 12 and 18-pulses, respectively. Based on these results magnetic elements can be calculated and designed leading to a great weight and volume reduction and also to lower costs and losses. Finally an analysis is made to improve the kVA rating of the transformers for 12 and 18 pulses converters. © 2009 IEEE.

Flujo de potencia AC descentralizado para sistemas de potencia multi-área usando un método de descomposición basado en relajación Lagrangiana

A decentralized solution method to the AC power flow problem in power systems with interconnected areas is presented. The proposed methodology allows finding the operation point of a particular area without explicit knowledge of network data of adjacent areas, being only necessary to exchange border information related to the interconnection lines between areas. The methodology is based on the decomposition of the first-order optimality conditions of the AC power flow, which is formulated as a nonlinear programming problem. A 9-bus didactic system, the IEEE Three Area RTS-96 and the IEEE 118 bus test systems are used in order to show the operation and effectiveness of the distributed AC power flow.

Projeto e simulação de um sistema de controle via LMIs da produção de vapor de uma caldeira aquatubular

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Projeto e implementação com chaveamento de reguladores fuzzy Takagi-Sugeno para um conjunto de pontos de operação

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Fluxo de carga continuado considerando o controle de intercâmbio entre áreas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Alocação ótima de reguladores de tensão em sistemas de distribuição de energia elétrica radiais usando uma formulação linear inteira mista. -

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo dos efeitos da compensação em derivação no desempenho dinâmico e transitório dos SEE sob o enfoque de energia transitória

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Controle de movimentos de pacientes paraplégicos utilizando modelos fuzzy T-S

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Análise da estabilidade estática de tensão de sistemas elétricos de potência usando uma rede neural baseada na teoria da ressonância adaptativa

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Modelos de programação inteira mista para a alocação ótima de bancos de capacitores em sistemas de distribuição de energia elétrica radias

Pós-graduação em Engenharia Elétrica - FEIS

Métodos de otimização aplicados no ajuste de ESPS e controladores de amortecimento inseridos no FACTS TCSC em sistemas elétricos de potência

Pós-graduação em Engenharia Elétrica - FEIS