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Publicações

Publicações por Carlos Moreira

2023

Including Dynamic Security Constraints in Isolated Power Systems Unit Commitment/Economic Dispatch: a Machine Learning-based Approach

Autores
de Sousa, RP; Moreira, C; Carvalho, L; Matos, M;

Publicação
2023 IEEE BELGRADE POWERTECH

Abstract
Isolated power systems with high shares of renewables can require additional inertia as a complementary resource to assure the system operation in a dynamic safe region. This paper presents a methodology for the day-ahead Unit Commitment/ Economic Dispatch (UC/ED) for low-inertia power systems including dynamic security constraints for key frequency indicators computed by an Artificial Neural-Network (ANN)-supported Dynamic Security Assessment (DSA) tool. The ANN-supported DSA tool infers the system dynamic performance with respect to key frequency indicators following critical disturbances and computes the additional synchronous inertia that brings the system back to its dynamic security region, by dispatching Synchronous Condensers (SC) if required. The results demonstrate the effectiveness of the methodology proposed by enabling the system operation within safe frequency margins for a set of high relevance fault type contingencies while minimizing the additional costs associated with the SC operation.

2005

Secondary load-frequency control for microgrids in islanded operation

Autores
Madureira, A; Faculty of Engineering of the University of Porto, INESC, Porto, Portugal,; Moreira, C; Pecas Lopes, J;

Publicação
Renewable Energy and Power Quality Journal

Abstract
The objective of this paper is to present novel control strategies for MicroGrid operation, especially in islanded mode. The control strategies involve mainly the coordination of secondary load-frequency control by a MicroGrid Central Controller that heads a hierarchical control system able to assure stable and secure operation when the islanding of the MicroGrid occurs and in load-following situations in islanded mode.

2006

Preliminary steady state and dynamic analysis of a microgrid system

Autores
Madureira, A; Moreira, C; Peças Lopes, J;

Publicação
Renewable Energy and Power Quality Journal

Abstract
The objective of this paper is to analyse the steady state and dynamic behaviour of a MicroGrid system containing one microturbine generating Combined Heat and Power feeding some small local loads in islanded mode of operation. Future operating scenarios were also analysed and simulated, namely considering the installation of photovoltaic panels near consumers.

2010

Economic and technical criteria for designing future off-shore HVDC grids

Autores
Bell, K; Cirio, D; Denis, AM; He, L; Liu, CC; Migliavacca, G; Moreira, C; Panciatici, P;

Publicação
2010 IEEE PES CONFERENCE ON INNOVATIVE SMART GRID TECHNOLOGIES EUROPE (ISGT EUROPE)

Abstract
In the scope of a recently launched European Research Project, a team of experts from public laboratories and TSO is in charge of defining the concepts and methodological approaches to design and analyse the technical and economic feasibility of future HVDC grids. This work aims at identifying, assessing and comparing several possible HVDC network topologies, with appropriate control and protection schemes, able to collect wind energy on large areas, transmit it at the best points to the AC grid and provide the necessary ancillary services for optimising the DC / AC interconnection in normal and disturbed conditions. The methodology adopted for the study and presented in this paper will focus on three main items: 1. identify and assess the economic drivers for the development of off-shore HVDC networks 2. identify the requirements for an optimal operation of the AC / DC interconnected power systems under normal and emergency conditions 3. conceptualise the coordinated control / command and protection plans for HVDC networks This paper gives a comprehensive view of the issues and tasks to be addressed during the run of the project.

2011

Contribution of PMSG based Small Wind Generation Systems to Provide Voltage Control in Low Voltage Networks

Autores
Rodrigues, JM; Resende, FO; Moreira, CL;

Publicação
2011 2ND IEEE PES INTERNATIONAL CONFERENCE AND EXHIBITION ON INNOVATIVE SMART GRID TECHNOLOGIES (ISGT EUROPE)

Abstract
This paper proposes technical solutions that can be implemented in variable speed permanent magnet synchronous generators driven wind turbine systems aiming to mitigate high voltage problems in low voltage MicroGrids by controlling the active power output. Due to the limited control capability of these systems, controlling the output power to prevent voltage rise will require the local accommodation of the generation surplus. For this purpose, additional control functionalities are developed to be integrated in the control systems of the power electronic based interfaces. Their performance is evaluated through numerical simulations performed in Matlab (R)/Simulink (R) environment and considering the detailed models of the power electronic converters. The results obtained demonstrate the effectiveness of the proposed control functionalities.

2012

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

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

Publicação
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.

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