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Publications

Publications by CPES

2013

Microgrids Emergency Management Exploiting EV, Demand Response and Energy Storage Units

Authors
Gouveia, C; Moreira, CL; Pecas Lopes, JAP;

Publication
2013 IEEE GRENOBLE POWERTECH (POWERTECH)

Abstract
Within the Smart Grid paradigm, the MicroGrid concept (MG) presents an adequate framework to monitor and manage the low voltage network and coordinate the resources connected to it, including the smart grid new players, namely the consumers, prosumers and the Electric Vehicles (EV). The coordinated management and control of the MG resources, enables the operation both connected to the main power network or autonomously, due to planned or unplanned outages. In order to operate autonomously, the MG relies in its storage capacity to provide some form of energy buffering capabilities to balance load and generation. This paper presents innovative methodology to coordinate the microgrid storage capacity with EV smart charging strategies and demand response schemes, in order to improve microgrid resilience in the moments subsequent to islanding and reduce the non-served load. The effectiveness of the proposed algorithms are validated though extensive numerical simulations.

2013

Power flow control with bidirectional dual active bridge battery charger in low-voltage microgrids

Authors
Miranda, LM; Varajao, D; Dos Santos, B; Araujo, RE; Moreira, CL; Lopes, JAP;

Publication
2013 15th European Conference on Power Electronics and Applications, EPE 2013

Abstract
This paper describes a power conversion system that implements bidirectional power flow between the electric grid and a battery, based on a full bridge inverter associated with a dual active bridge. A method for power flow control based on the agreement between battery pack and low voltage grid requirements has been developed to allow the large penetration of both, electric vehicles (EV) and renewable microgeneration. A laboratory prototype containing all functions required to implement a vehicle-to-grid (V2G) power interface has been built. The hardware implementation is reported, including control scheme and high-frequency transformer design details. Converter key waveforms are presented to evaluate the power quality on batteries and grid, as well as its dynamic behavior. An experimental laboratory setup is described and results are shown to demonstrate the technical benefits for low-voltage (LV) microgrids, if electric vehicle charger includes a power flow control based on frequency-voltage droop concept. © 2013 IEEE.

2013

An innovative strategy for power system restoration using utility scale wind parks

Authors
Seca, L; Costa, H; Moreira, CL; Lopes, JAP;

Publication
Proceedings of IREP Symposium: Bulk Power System Dynamics and Control - IX Optimization, Security and Control of the Emerging Power Grid, IREP 2013

Abstract
This paper presents an innovative Power System Restoration (PSR) that exploits the flexibility offered by large offshore wind parks, in particular with HVDC connection with Voltage Source converter (VSC) technology, to support restoration following a black out in a typical transmission grid. Restoration sequences comparing different strategies in a VHV AC network with conventional generation (thermal units and hydro units) were implemented for two cases: with and without the participation of a large offshore wind farm in the restoration plan. In order to evaluate the benefit of using Utility scale Wind Parks to support PSR, a typical transmission network with all its models (including HVDC link with DC converter) was implemented in EUROSTAG simulation platform. © 2013 IEEE.

2013

A view of microgrids

Authors
Pecas Lopes, JAP; Madureira, AG; Leal Monteiro Moreira, CCLM;

Publication
WILEY INTERDISCIPLINARY REVIEWS-ENERGY AND ENVIRONMENT

Abstract
Large-scale integration of distributed energy resources in low voltage distribution grids will have a serious impact on power system operation. The development of the microgrid concept is presented as a solution to overcome some of the negative impacts of massive microgeneration deployment. It has paved the way for an active network management approach within the smart grid paradigm. The microgrid concept is able to address the integration of geographically dispersed energy resources, thus avoiding significant technical problems that may affect the security of operation. (C) 2012 John Wiley & Sons, Ltd.

2013

Advanced models and simulation tools to address electric vehicle power system integration (steady-state and dynamic behavior)

Authors
Soares, FJ; Almeida, PMR; Lopes, JAP;

Publication
Electric Vehicle Integration into Modern Power Networks

Abstract

2013

Evaluation of the benefits of the introduction of electricity powered vehicles in an island

Authors
Baptista, PC; Silva, CM; Pecas Lopes, JAP; Soares, FJ; Almeida, PR;

Publication
ENERGY CONVERSION AND MANAGEMENT

Abstract
This paper evaluates the benefits of introducing electricity powered vehicles (EV) in one island of the Azores archipelago in Portugal, the island of Flores. A Life Cycle Analysis (LCA) for the road transportation sector including EV was performed and the EV impacts in the electricity grid were evaluated. Two scenarios considering the introduction of EV were considered (Scenarios 2 and 3 with a shift in the car stock in 2050 of 30% and 70% to EV) and compared to the baseline scenario (Scenario 1 with no EV penetration). The results show that, if no alternative solutions are adopted, the road transportation sector LCA energy consumption will increase 58% in 2050, compared to 2009. In the most attractive scenario studied regarding EV integration in Flores, the LCA energy consumption in 2050 decreases by 34% and CO2 emissions by 39%, when comparing with Scenario 1. Moreover, the island's electricity network is ready for EV arrival, at least until 2020. Thereafter, a smart charging scheme should be implemented to manage the vehicles' energy demand according to the network technical limitations and the presence of Renewable Energy Sources (RES) should be reinforced, to decrease the island's dependency on fossil fuels and, consequently, CO2 emissions.

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