2005
Autores
Peças Lopes, JA; Moreira, CL; Resende, FO;
Publicação
15th Power Systems Computation Conference, PSCC 2005
Abstract
A low voltage distribution network with large amounts of small sized dispersed generation can be operated as an isolated system in certain conditions. This paper presents the control strategies to be used in such a system to deal with islanded operation and to exploit the local generation resources as a way to help in power system restoration after a general blackout. A sequence of actions for the black start procedure is identified and it is expected to be an advantage for power system operation in terms of reliability as a result from the presence of a very large amount of dispersed generation.
2010
Autores
Pereira Barbeiro, PN; Moreira, CL; Soares, FJ; Rocha Almeida, PM;
Publicação
2010 IEEE Conference on Innovative Technologies for an Efficient and Reliable Electricity Supply, CITRES 2010
Abstract
This paper presents a methodology for evaluating the impact resulting from the expected large scale integration of micro-generation (µG) in Low Voltage (LV) grids in Portugal. The proposed methodology allows the evaluation of the impacts in the entire LV and Medium Voltage (MV) distribution network by using typical load and generation profiles (24 hours) representing two well defined year periods (Summer and Winter). The simulations were performed in a time interval from 2008 to 2030, upon the definition of future scenarios related to the expected µG installed power in Portugal in the same period. Based on the obtained results, it was possible to quantify percentage gains related to the reduction of energy losses as a result of µ G integration in LV networks, avoided CO2 emissions and the possibility of achieving investment deferrals due to branches' congestion levels reduction or voltage profile improvements. ©2010 IEEE.
2011
Autores
Soares, FJ; Peças Lopes, JA; Rocha Almeida, PM; Moreira, CL; Seca, L;
Publicação
17th Power Systems Computation Conference, PSCC 2011
Abstract
The uncertainties related to when and where electric vehicles will charge in the future requires the development of stochastic based approaches to identify the corresponding load scenarios. This paper describes a tool based on Monte Carlo techniques to be used for distribution grid planning, providing a characterization of possible grid operation conditions, regarding voltage profiles, branch loading, grid peak power and energy losses. A medium voltage network based on real data is used to illustrate the application of the developed methodology.
2010
Autores
Lopes, JAP; Almeida, PMR; Soares, FJ; Moreira, CL;
Publicação
IFAC Proceedings Volumes (IFAC-PapersOnline)
Abstract
This paper presents a conceptual framework to enable a successful integration of Electric Vehicles (EV) into isolated power systems. The developed framework includes the management and control actions that might be implemented over EV in order to improve the system's resilience. Several dynamic stability simulations were performed, using a small isolated grid as a test system, in order to demonstrate the possible contributions EV may provide to fast power/frequency control, either as a highly flexible and controllable load and/or as an energy storage device.
2012
Autores
Silva, B; Moreira, CL; Seca, L; Phulpin, Y; Pecas Lopes, JAP;
Publicação
IEEE TRANSACTIONS ON SUSTAINABLE ENERGY
Abstract
This paper addresses the problem of providing frequency control services, including inertia emulation and primary frequency control, from offshore wind farms connected through a multiterminal HVDC network. The proposed strategy consists of a cascading control mechanism based on dc voltage regulation at the onshore converters and frequency regulation at the offshore converters. The control scheme involves only local measurements and actions avoiding security and reliability issues of control structures based on remote information. The effectiveness of the proposed strategy is illustrated in a test system that consists of two nonsynchronous areas linked by a multiterminal HVDC grid where two offshore wind farms are also connected.
2006
Autores
Lopes, JAP; Moreira, CL; Madureira, AG;
Publicação
IEEE TRANSACTIONS ON POWER SYSTEMS
Abstract
This paper describes and evaluates the feasibility of control strategies to be adopted for the operation of a microgrid when it becomes isolated. Normally, the microgrid operates in interconnected mode with the 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. An evaluation of the need of storage devices and load shedding strategies is included in this paper.
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