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Publications

Publications by João Peças Lopes

1995

REAL-TIME PREVENTIVE ACTIONS FOR TRANSIENT STABILITY ENHANCEMENT WITH A HYBRID NEURAL-NETWORK - OPTIMIZATION APPROACH

Authors
MIRANDA, V; FIDALGO, JN; LOPES, JAP; ALMEIDA, LB;

Publication
IEEE TRANSACTIONS ON POWER SYSTEMS

Abstract
This paper reports a new approach in defining preventive control measures to assure transient stability relatively to one or several contingencies that may occur separately in a power system. Generation dispatch is driven not only by economic functions but also with the derivatives of the transient energy margin value; these derivatives are obtained directly from a trained Artificial Neural Network (ANN), using ri:al time monitorable system values. Results obtained from computer simulations, for several contingencies in the CIGRE test system, confirm the validity of the developed approach.

1996

Neural networks applied to preventive control measures for the dynamic security of isolated power systems with renewables

Authors
Fidalgo, JN; Lopes, JAP; Miranda, V;

Publication
IEEE TRANSACTIONS ON POWER SYSTEMS

Abstract
This paper presents an artificial neural network (ANN) based approach for the definition of preventive control strategies of autonomous power systems with a large renewable power penetration. For a given operating point, a fast dynamic security evaluation for a specified wind perturbation is performed using an ANN. If insecurity is detected, new alternative stable operating points are suggested, using a hybrid ANN-optimization approach that checks several feasible possibilities, resulting from changes in power produced by diesel and wind generators, and other combinations of diesel units in operation, Results obtained from computer simulations of the real power system of Lemnos (Greece) support the validity of the developed approach.

2004

Metaheuristics applied to power systems

Authors
Matos, MA; de Leao, MTP; Saraiva, JT; Fidalgo, JN; Miranda, V; Lopes, JP; Ferreira, JR; Pereira, JMC; Proenca, LM; Pinto, JL;

Publication
METAHEURISTICS: COMPUTER DECISION-MAKING

Abstract
Most optimization and decision problems in power systems include integer or binary variables, leading to combinatorial problems. In this paper, several approaches using metaheuristics and genetic algorithms are presented that deal with real problems of the power industry Most of these methodologies are now implemented in distribution management systems (DMS) used by several utilities.

1999

New GIS tools for biomass resource assessment in electrical power generation

Authors
Monteiro, C; da Rocha, BRP; Miranda, V; Lopes, JP;

Publication
BIOMASS: A GROWTH OPPORTUNITY IN GREEN ENERGY AND VALUE-ADDED PRODUCTS, VOLS 1 AND 2

Abstract

2000

Intelligent tools in a real-world DMS environment

Authors
Miranda, V; Matos, M; Lopes, JP; Saraiva, JT; Fidalgo, JN; de Leao, MTP;

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

Abstract
This text describes a real-world DMS environment in which intelligent tools and techniques such as neural networks, fuzzy sets and meta-heuristics (like evolutionary computing and simulated annealing) have given a strong positive contribution.

2023

Modeling demand flexibility impact on the long-term adequacy of generation systems

Authors
Alves, IM; Carvalho, LM; Lopes, JAP;

Publication
INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS

Abstract
This paper proposes a novel probabilistic model for quantifying the impact of demand flexibility (DF) on the long-term generation system adequacy via Sequential Monte Carlo Simulation (SMCS) method. Unlike load shedding, DF can be considered an important instrument to postpone bulk consumption from periods with limited reserves to periods with more generating capacity available, avoiding load shedding and increasing the integration of variable renewable generation, such as wind power. DF has been widely studied in terms of its contribution to the system's social welfare, resulting in numerous innovative approaches ranging from the flexibility modeling of individual electric loads to the definition of aggregation strategies for optimally deploying this lever in competitive markets. To add to the current state-of-the-art, a new model is proposed to quantify DF impact on the traditional reliability indices, such as the Loss of Load Expectation (LOLE) and the Expected Energy Not Supplied (EENS), enabling a new perspective for the DF value. Given the diverse mechanisms associated with DF of different consumer types, the model considers the uncertainties associated with the demand flexibility available in each hour of the year and with the rebound effect, i.e., the subsequent change of consumption patterns following a DF mobilization event. Case studies based on a configuration of the IEEE-RTS 79 test system with wind power demonstrate that the DF can substantially improve the reliability indices of the static and operational reserve while decreasing the curtailment of variable generation cause by unit scheduling priorities or by short-term generation/demand imbalances.

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