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Publicações

Publicações por João Peças Lopes

2004

Bounding active power generation of a wind-hydro power plant

Autores
Castronuovo, ED; Lopes, JAP;

Publicação
2004 INTERNATIONAL CONFERENCE ON PROBABILISTIC METHODS APPLIED TO POWER SYSTEMS

Abstract
In the usual operation, wind park production is strongly dependent on the instantaneously available wind power. When energy storage is accessible, the wind park operation can be improved, aiming to a better exploitation of the available wind power resource. The present work proposes an optimization approach to determinate the most probable range of the output production, to be used in the definition of production profiles that will help the participation of wind power in the market. Two production profiles strategies were analyzed and compared. The forecasted wind power is represented as a stochastic variable and real wind power Portuguese conditions have been used in the evaluation of the model.

1999

Application of artificial neural networks to dynamic security assessment of electric power systems

Autores
Lopes, JAP;

Publicação
ENGINEERING INTELLIGENT SYSTEMS FOR ELECTRICAL ENGINEERING AND COMMUNICATIONS

Abstract
This paper describes the main steps needed to apply neural networks in the domain of dynamic security assessment (DSA). The paper provides also an overview of the application of neural networks in DSA. Special emphasis is given to the application of this approach in a medium size real system where a large penetration of wind power is foreseen.

2005

Control strategies for MicroGrids emergency operation

Autores
Pecas Lopes, JA; Moreira, CL; Madureira, AG; Resende, FO; Wu, X; Jayawarna, N; Zhang, Y; Jenkins, N; Kanellos, F; Hatziargyriou, N;

Publicação
2005 International Conference on Future Power Systems (FPS)

Abstract
Under normal operating conditions, a MicroGrid (MG) is interconnected with the Medium Voltage (MV) network. However, planned or unplanned events like maintenance or faults in the MV network, respectively, may lead to MG islanding. In order to deal with islanded operation and even black start following a general blackout, an emergency operation mode must be envisaged. Two possible control strategies were investigated and are described in this paper in order to operate a MG under emergency mode. A sequence of actions for a well succeeded black start procedure, involving microgeneration units, has also been identified contributing for an increase in distribution network reliability.

2005

Impact of large scale wind power integration on small signal stability

Autores
Mendonca, A; Pecas Lopes, JAP;

Publicação
2005 International Conference on Future Power Systems (FPS)

Abstract
This paper deals with the problem of large wind power integration and its potential impact on systems small signal stability. Factors like grid configuration, load and wind power integration are considered. An automatic algorithm is used to search the space formed by such parameters and generate a representative set of possible operation conditions. The oscillation modes are then calculated for each operation point. Some of these points of operation are subjected to a deeper analysis and the movement of oscillation modes on the complex plane is evaluated. Finally, non-linear time domain simulations are presented.

2005

Intentional islanding for reliability improvement in distribution networks with high DG penetration

Autores
Seca, L; Lopes, JAP;

Publicação
2005 International Conference on Future Power Systems (FPS)

Abstract
In this paper, a new operational strategy regarding islanding operation is presented exploiting Distributed Generation for islanding; purposes. The presence of DG may be used to enhance reliability to final consumers by providing an alternative power source when there is an interruption in the upstream network. The feasibility of this type of operation in distribution networks is analyzed in a case study by analyzing the behavior of different generating units and protection settings.

2002

Integration of dispersed generation on distribution networks - Impact studies

Autores
Lopes, JAP;

Publicação
2002 IEEE POWER ENGINEERING SOCIETY WINTER MEETING, VOLS 1 AND 2, CONFERENCE PROCEEDINGS

Abstract
This paper describes the general methodology that should be adopted to develop impact evaluation studies in distribution networks in case of connection of large amounts of dispersed generation (DG). It contains a description regarding the characterization of scenarios to be analyzed, problems to be addressed and tools to be used. Results from the analysis of a real network, where a large amount of dispersed generation (cogeneration) exists, are described. Technical issues to be tackled in the future and conclusions obtained from the studied examples are included.

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