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Publications

Publications by CPES

2008

Well-being analysis for composite generation and transmission systems based on pattern recognition techniques

Authors
Leite da Silva, AML; de Resende, LC; da Fonseca Manso, LAD; Miranda, V;

Publication
IET GENERATION TRANSMISSION & DISTRIBUTION

Abstract
A new methodology to evaluate well-being indices for a composite generation and transmission system, based on non-sequential Monte Carlo simulation and pattern recognition techniques, is presented. To classify the success operating states into healthy and marginal, an artificial neural network based on group method data handling techniques is used to capture the patterns of these state classes, during the beginning of the simulation process. The idea is to provide the simulation process with an intelligent memory, based on polynomial parameters, to speed up the evaluation of the operating states. The proposed methodology is applied to the IEEE reliability test system (IEEE-RTS), to the IEEE-RTS-96 and to a configuration of the Brazilian South-Southeastern system.

2008

Fibre Fabry-Perot sensor for acoustic detection

Authors
Lima, SEU; Frazao, O; Araujo, FM; Ferreira, LA; Miranda, V; Santos, JL;

Publication
19TH INTERNATIONAL CONFERENCE ON OPTICAL FIBRE SENSORS, PTS 1 AND 2

Abstract
Incipient fault diagnosis is closely related to isolation condition assessment. There are a great number of methods available for condition monitoring and diagnosis of power transformer isolation systems, but only few of them can take direct measurements inside the transformer. Fibre optic sensors can be applied to incipient fault diagnosis. In special, acoustic sensors are being developed for the detection and location of partial discharges in oil-filled power transformers. Towards such objective, this work reports investigation on the applicability of fibre Fabry-Perot interferometers for acoustic detection both in air and in liquids.

2008

Wind Power Forecasting With Entropy-Based Criteria Algorithms

Authors
Bessa, R; Miranda, V; Gama, J;

Publication
2008 10TH INTERNATIONAL CONFERENCE ON PROBABILISTIC METHODS APPLIED TO POWER SYSTEMS

Abstract
This paper reports new results in adopting entropy concepts to the training of mappers such as neural networks to perform wind power prediction as a function of wind characteristics (mainly speed and direction) in wind parks connected to a power grid. Renyi's Entropy is combined with a Parzen Windows estimation of the error pdf to form the basis of three criteria (MEE, MCC and MEEF) under which neural networks are trained. The results are favourably compared with the traditional minimum square error (MSE) criterion. Real case examples for two distinct wind parks are presented.

2008

Probabilistic evaluation of reserve requirements of generating systems with renewable power sources: The Portuguese and Spanish cases

Authors
Matos, M; Lopes, JP; Rosa, M; Ferreira, R; Da Silva, AL; Sales, W; Resende, L; Manso, L; Cabral, P; Ferreira, M; Martins, N; Artaiz, C; Soto, F; López, R;

Publication
16th Power Systems Computation Conference, PSCC 2008

Abstract
This paper presents an application of probabilistic methodologies to evaluate the reserve requirements of generating systems with large amounts of renewable energy sources. The idea is to investigate the behavior of reliability indices, including those from the well-being analysis, when the major portion of the renewable sources comes from the wind power. Renewable in this work mainly comprises hydroelectric, minihydroelectric and wind power sources. Case studies on configurations of the Portuguese and Spanish generating systems are presented and discussed.

2008

The fuzzy power flow revisited

Authors
Matos, MA; Gouveia, EM;

Publication
IEEE TRANSACTIONS ON POWER SYSTEMS

Abstract
The idea behind the first proposal of the fuzzy power flow (FPF) was to analyze the impact of the uncertainties in load and generation at the power flow level, when no statistical information is available. Further development of the field addressed the optimal power flow problem and the use of fuzzy methodologies to help planners of the composite generation-transmission system. In a market environment, transmission system adequacy may be defined as the ability of the system to meet reasonable demands for the transmission of electricity. The starting point of this paper is that FPF can be used as a tool to quantify this adequacy, without the need of making too many assumptions about load and generation uncertainties. However, some changes in the basic concept of the FPF are needed in order to accomplish this task-part of this paper is devoted to the description of the adequate formulation. We will also show that this formulation can be used both in the normal operation situation and in the reliability evaluation of the transmission system. An illustrative example completes this paper.

2008

Optimization of pumped storage capacity in an isolated power system with large renewable penetration

Authors
Brown, PD; Pecas Lopes, JAP; Matos, MA;

Publication
IEEE TRANSACTIONS ON POWER SYSTEMS

Abstract
This work describes an economic analysis of the inclusion of pumped storage in a small island system that has abundant renewable energy available but that at times cannot accept all of this power because of limits imposed by security criteria. The question of whether or how much pumped storage to include is addressed by formulating a linear programming optimization problem. The stochastic nature of load and renewable production is addressed using scenarios developed through fuzzy clustering. Both the unit capacity in MW and the reservoir storage capacity in MWh are optimized, and optimal operating strategies for the scenarios are produced. Results showed that including pumped storage can be an effective means of allowing larger penetration of intermittent renewable energy sources, improving both the dynamic security and the economic operation of a test system. Including the dynamic security criteria in the economic question of dimensioning the pumped storage unit proved to make a significant difference in the optimal pumped storage capacity.

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