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Publications

Publications by João Peças Lopes

2001

ANN sensitivity analysis for identification of relevant features in security assessment

Authors
Fidalgo, JN; Pecas Lopes, JA;

Publication
2001 IEEE Porto Power Tech Proceedings

Abstract
This paper deals with a problem of identification of the best subset of variables that should be used for dynamic security assessment of a power system, when this task is pro-vided by artificial neural networks (ANN)- The approach de-scribed here exploits ANN output sensitivities relatively to the inputs and correlation degrees, to identify the most relevant system variables to be used for an effective security assessment task. The ANNs are initially trained with all low-correlated candidate features, which enables the sensitivity analyses for the initial set of system features. Derivatives of the ANN output relatively to each input are obtained by exploiting the chain rule, similar to the one used for weights adaptation on Back-propagation Algorithm. A description of the application of this approach in a real system is present in the paper. Results obtained in the dynamic security assessment problem of the network of the island of Crete were quite successful. © 2001 IEEE.

1999

On-line dynamic security assessment of isolated networks integrating large wind power production

Authors
Pecas Lopes, JA; Hatziargyriou, N; Vasconcelos, M; Karapidakis, E; Fidalgo, J;

Publication
Wind Engineering

Abstract
The paper describes the on-line dynamic security assessment functions developed within the European Union, DGXII programme, CARE. These functions are based exclusively on the application of machine learning techniques. A description of the problem and the data set generation procedure for the Crete island power system are included. Comparative results regarding performances of Decision Trees, Kernel Regression Trees and Neural Networks are presented and discussed.The paper describes the on-line dynamic security assessment functions developed within the European Union, DGXII programme, CARE. These functions are based exclusively on the application of machine learning techniques. A description of the problem and the data set generation procedure for the Crete island power system are included. Comparative results regarding performances of Decision Trees, Kernel Regression Trees and Neural Networks are presented and discussed.

2000

Using a neural network to predict the dynamic frequency response of a power system to an under-frequency load shedding scenario

Authors
Mitchel, MA; Lopes, JAP; Fidalgo, JN; McCalley, JD;

Publication
2000 IEEE POWER ENGINEERING SOCIETY SUMMER MEETING, CONFERENCE PROCEEDINGS, VOLS 1-4

Abstract
This paper proposes a method to quickly and accurately predict the dynamic response of a power system during an under-frequency load shedding scenario. Emergency actions in a power system due to loss of generation typically calls for under-frequency load shedding measures to avoid potential collapse due to the lack of time in which to correct the imbalance via other means. Due to the slow and repetitious use of dynamic simulators the need for a fast and accurate procedure is evident when calculating optimal bad-shedding strategies A neural network (NN) seems to he an ideal solution for a quick and accurate way to replace standard dynamic simulations. The steps taken to produce a viable NN and corresponding results will he discussed.

2011

Models for the EV aggregation agent business

Authors
Bessa, RJ; Soares, FJ; Pecas Lopes, JA; Matos, MA;

Publication
2011 IEEE PES Trondheim PowerTech: The Power of Technology for a Sustainable Society, POWERTECH 2011

Abstract
It is foreseeable that electricity retailers for electrical mobility will be market agents. These retailers are electric vehicle (EV) aggregation agents, which operate as a commercial middleman between electricity market and EV owners. Furthermore, with the foreseen evolution of the smart-grid concept, these agents will be able to control the EV charging rates and offer several ancillary services. This paper formulates an optimization problem for the EV aggregation agent participation in the day-ahead and secondary reserve market sessions. Forecasting issues are also discussed. The methodology was tested for two years (2009 and 2010) of the Iberian market, considering perfect and naïve forecast for all variables of the problem. © 2011 IEEE.

2012

Optimized Bidding of a EV Aggregation Agent in the Electricity Market

Authors
Bessa, RJ; Matos, MA; Soares, FJ; Pecas Lopes, JAP;

Publication
IEEE TRANSACTIONS ON SMART GRID

Abstract
An electric vehicle (EV) aggregation agent, as a commercial middleman between electricity market and EV owners, participates with bids for purchasing electrical energy and selling secondary reserve. This paper presents an optimization approach to support the aggregation agent participating in the day-ahead and secondary reserve sessions, and identifies the input variables that need to be forecasted or estimated. Results are presented for two years (2009 and 2010) of the Iberian market, and considering perfect and naive forecast for all variables of the problem.

2001

Contents

Authors
Lopes, J; Matos, M;

Publication
IEEE Power Engineering Review - IEEE Power Eng. Rev.

Abstract

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