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Publications

Publications by CPES

2012

Hybrid Evolutionary Neuro-fuzzy Computational Tool to Forecast Wind Power and Electricity Prices

Authors
Osorio, GJ; Pousinho, HMI; Matias, JCO; Monteiro, C; Catalao, JPS;

Publication
TECHNOLOGICAL INNOVATION FOR VALUE CREATION

Abstract
The intermittence of the renewable sources due to its unpredictability increases the instability of the actual grid and energy supply. Besides, in a deregulated and competitive framework, producers and consumers require short-term forecasting tools to derive their bidding strategies to the electricity market. This paper proposes a novel hybrid computational tool, based on a combination of evolutionary particle swarm optimization with an adaptive-network-based fuzzy inference system, for wind power forecasting and electricity prices forecasting in the short-term. The results from two real-world case studies are presented, in order to illustrate the proficiency of the proposed computational tool.

2012

Dynamics and control of Multi-Terminal high voltage direct current networks for integration of large offshore wind parks into AC grids

Authors
Ciapessoni, E; Cirio, D; Gatti, A; Pitto, A; Denis, AM; Despouys, O; He, L; Liu, CC; Moreira, C; Silva, B; Phulpin, Y;

Publication
44th International Conference on Large High Voltage Electric Systems 2012

Abstract
The integration of larger and larger amounts of wind power is a major target of the European Union, however it represents a challenge for power system planning and operation. The paper analyses stability aspects concerning the operation of Multi-Terminal HVDC networks connecting offshore wind farms to the AC systems. Modelling issues are tackled, relevant to control schemes needed for a secure operation of the overall AC-DC system in case of contingencies both on the AC side and on the DC side. First, power flow control principles are described for the "backbone" HVDC grid topology (consisting of point-to-point connections between offshore wind farms and mainland grid, linked by a DC connection). Second, dynamic converter models suitable to investigate electromechanical transients are illustrated and some stability issues connected to the network performance under contingencies/disturbances are pointed out. The need both to survive severe disturbances and to provide ancillary services calls for the adoption of advanced control schemes. Some simulations are described to illustrate the behaviour of the mixed AC-DC network under contingencies concerning both faults on DC cables and faults on AC lines. The work has been carried out within Working Package 5 of EU co-founded Project TWENTIES.

2012

Methodologies to Determine Operating Reserves Due to Increased Wind Power

Authors
Holttinen, H; Milligan, M; Ela, E; Menemenlis, N; Dobschinski, J; Rawn, B; Bessa, RJ; Flynn, D; Gomez Lazaro, E; Detlefsen, NK;

Publication
IEEE TRANSACTIONS ON SUSTAINABLE ENERGY

Abstract
Power systems with high wind penetration experience increased variability and uncertainty, such that determination of the required additional operating reserve is attracting a significant amount of attention and research. This paper presents methods used in recent wind integration analyses and operating practice, with key results that compare different methods or data. Wind integration analysis over the past several years has shown that wind variability need not be seen as a contingency event. The impact of wind will be seen in the reserves for nonevent operation ( normal operation dealing with deviations from schedules). Wind power will also result in some events of larger variability and large forecast errors that could be categorized as slow events. The level of operating reserve that is induced by wind is not constant during all hours of the year, so that dynamic allocation of reserves will reduce the amount of reserves needed in the system for most hours. The paper concludes with recent emerging trends.

2012

Extending the International Dimension of Life Long Learning

Authors
Martins, MJ; Maciel Barbosa, FM;

Publication
2012 15TH INTERNATIONAL CONFERENCE ON INTERACTIVE COLLABORATIVE LEARNING (ICL)

Abstract
In this paper the contributions of the ELLEIEC project for the international dimension of Life Long Learning (LLL) are described. In the framework of the Thematic Networks Programme, tools such as Recognition of Prior Learning (RPL), the Tuning Methodology were used in the implementation of an International Curricula Network with accreditation by two European institutions at least. Benchmarks were proposed, in order to show various tools that can be used for the establishment of dual degree programmes

2012

Performance metrics for evaluation of a mixed measurement based state estimator

Authors
Vide, PC; Barbosa, FM; Carvalho, JB;

Publication
Proceedings of 9th International Conference, ELEKTRO 2012

Abstract
With the development of synchronized phasor measurement technology in recent years, it gains great interest the use of PMU measurements to improve state estimation performances. In this paper, a mixed measurement (SCADA and PMU measurements) state estimator is proposed. Several measures useful for evaluating various aspects of the performance of the mixed measurement state estimator are proposed and explained. State Estimator validity, performance and characteristics of the results on IEEE 14 bus test system are presented. © 2012 IEEE.

2012

Influence of the reactive power management for wind power plants in the dynamic voltage stability [Wplyw zarza¸dzania moca¸ bierna¸ na dynamiczna¸ stabilnosc napi?cia w elektrowniach wiatrowych]

Authors
Pereira, RMM; Ferreira, CMBM; Barbosa, FPM;

Publication
Przeglad Elektrotechniczny

Abstract
Nowadays, the large penetration of wind power generation poses new challenges for the dynamic voltage stability analysis of an electric power system. In this paper is studied the influence of the reactive power management for wind power plants in the dynamic voltage stability of an electric power network under a fault condition, considering two different Doubly-Fed Induction Generators (DFIG) models. The simulation results were obtained using the EUROSTAG software package.

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