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Publicações

Publicações por CPES

2010

MICROGRIDS OPERATION AND CONTROL UNDER EMERGENCY CONDITIONS

Autores
Moreira, CL; Pecas Lopes, JAP;

Publicação
INTELLIGENT AUTOMATION AND SOFT COMPUTING

Abstract
Under normal conditions, the MicroGrid operates interconnected with the upstream medium voltage network. However, scheduled or forced isolation can take place. In such conditions, the MicroGrid must have the ability to operate stably and autonomously, requiring the development of suitable control strategies in order to enable MicroGrid islanded operation. The MicroGrid power sources can also be exploited in order to locally promote a service restoration strategy following a general blackout. A sequence of actions for the black start procedure is also identified and it is expected to be an advantage for power system operation in terms of reliability as a result from the presence of very large amounts of dispersed generation in distribution grids.

2010

Identification of control and management strategies for LV unbalanced microgrids with plugged-in electric vehicles

Autores
Pecas Lopes, JAP; Polenz, SA; Moreira, CL; Cherkaoui, R;

Publicação
ELECTRIC POWER SYSTEMS RESEARCH

Abstract
This paper addresses issues concerning the integration of single-phase charging devices for electric vehicles (EV) in low-voltage microgrids Fast release energy storage is a key issue for microgrid islanding operation. EV batteries provide an additional storage capacity, which can now be exploited in order to improve MG islanding Aiming to do so, different control strategies were developed and tested (1) a local control approach where no communication link is required and (2) a centralized charging control solution The local control approach is based on the measuring of EV terminal voltage and frequency in order to define the charging or discharging rates of the batteries The centralized control strategy allows balancing single-phase loads connected to the microgrid by adapting the charging rates of the EV storage devices. Simulation results show that EV batteries can actively contribute for voltage balancing and frequency control during islanding operating conditions

2010

Islanding Operation of Active Distribution Grids using an Agent-based Architecture

Autores
Issicaba, D; Gil, NJ; Pecas Lopes, JAP;

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

Abstract
This paper presents a decentralized architecture for the islanding operation of distribution grids with large volume of distributed generation. This architecture involves the definition of network blocks which share the responsibility of frequency control. The control block abstraction was particularly designed to support the transition from regular grids to smart grids. In addition, the control schemes were developed using an agent-based paradigm. Hence, an agent-based simulation platform was implemented using libraries from the Java Agent Development Framework (JADE). The control schemes were evaluated using a test system with different sorts of distributed energy resources and modeled in the EUROSTAG environment. Simulation results show the effectiveness of the control architecture when different failure events are applied to the test system.

2010

Advanced Metering Infrastructure Functionalities for Electric Mobility

Autores
Rua, D; Issicaba, D; Soares, FJ; Almeida, PMR; Rei, RJ; Lopes, JAP;

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

Abstract
The Smart Grid vision along with the future deployment of Electric Vehicles presents numerous challenges in terms of grid infrastructure, communication, and control. In this context, Advanced Metering Infrastructure solutions are envisioned to be the active management link between utilities and consumers. This paper presents a survey of potential AMI functionalities particularly developed to foster the large scale deployment of EV in Smart Grids. For this accomplishment, the concepts of Automated Meter Reading, Automatic Meter Management and Smart Metering are revisited. Furthermore, different EV charging approaches are outlined and included in the functionalities under the Vehicle-To-Grid framework. Finally, AMI use cases are described under the Vehicle-to-Home perspective.

2010

Automatic generation control operation with electric vehicles

Autores
Rocha Almeida, PM; Pecas Lopes, JA; Soares, FJ; Vasconcelos, MH;

Publicação
2010 IREP Symposium - Bulk Power System Dynamics and Control - VIII, IREP2010

Abstract
This paper presents a methodology to make EV able to contribute to secondary frequency regulation, by participating in Automatic Generation Control (AGC). The aggregator entity is used in this methodology to act as intermediate between the AGC and the EV controllers. The case-study used is an approximation of the Portuguese transmission/generation network, including existing tie lines with Spain, to which a solid three-phase short circuit was applied. After the disturbance, the impact of EV in the AGC operation was studied for two different situations: EV contributing to secondary frequency regulation and EV behaving as uncontrollable loads. The results obtained for both situations were then compared, in terms of interconnection active power flows in the existing tie-lines and its re-establishment time. ©2010 IEEE.

2010

Dynamic stability and control design of modern electric energy systems with large penetration of distributed generators

Autores
Nazari, MH; Ilic, M; Lopes, JAP;

Publicação
2010 IREP Symposium - Bulk Power System Dynamics and Control - VIII, IREP2010

Abstract
This paper investigates dynamic stability and control design of modern electric energy systems as many MW-scale distributed generators (DG) of various types are deployed in the distribution side of electric systems. The paper is mainly concerned about small-signal frequency stability of distribution systems with decentralized or centralized control systems. The Gerschgorin Circle Theory and Hicks Stability Theory are used for verifying sufficient conditions for small-signal stability. The paper also discusses about designing advanced enhancing robustness methods to ensure both safety and stability of modern distribution systems. Finally, the paper closes with a discussion of policies needed to support large penetration of DG units in distribution systems to ensure safety and robustness of the system. ©2010 IEEE.

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