2011
Autores
Rocha Almeida, PM; Moreira, CL; Soares, F; Pecas Lopes, JA;
Publicação
CIGRE 2011 Bologna Symposium - The Electric Power System of the Future: Integrating Supergrids and Microgrids
Abstract
From the studies developed so far, it is a general consensus that Electric Vehicles (EV), when properly managed, can provide many benefits to the grid operation. In the power systems of islands the potential benefits may be even larger. The case of S. Miguel Island, in the Azorean archipelago, may be one of such cases. This island achieves typically an annual peak power of 75 MW and a valley slightly higher than 30 MW. Currently, around 75% of its installed capacity is formed by fuel units, 22% by geothermal units and the rest by small hydro units. Yet, there are numerous unexplored endogenous resources in this place, especially geothermal and wind power, which cannot be used due to technical restrictions. Geothermal is limited by the valley load as the involved technology is not suited for load following, even with very small ramp rates. Wind power requires sufficient conventional spinning reserve to be safely integrated due to the variability of the wind resource. High EV integration, with an adequate charging management, would then increase base load allowing further geothermal and a reduced need for conventional spinning reserves. This paper evaluates the benefits of the presence of EV as controllable loads performing frequency control in a scenario with abundant wind resource availability, where a sudden loss of wind power production over a short period of time occurs. Ultimately, this work will show that S. Miguel power system would benefit from the presence of EV. A comparison with the conventional approach considering EV as regular loads will also be performed for benchmarking purposes.
2011
Autores
Moreira, CL; Silva, B; Soares, FJ; Seca, L; Pecas Lopes, JA;
Publicação
CIGRE 2011 Bologna Symposium - The Electric Power System of the Future: Integrating Supergrids and Microgrids
Abstract
The massive interconnection of offshore Wind Farms (WF) brings challenges for the operation of electric grids. The predicted amount of offshore wind power will lead to a smaller ratio of conventional units operating in the system. Thus, the power system will have less capability to provide fast dynamic regulation. Despite of offshore WF being able to inject power on the AC grid through High Voltage Direct Current (HVDC) convertors, they cannot participate on frequency support by the intrinsic decoupling that DC adoption brings. This paper proposes a control methodology, based on local controllers, to enable the participation of offshore WF in primary frequency control. Additionally, enhancements were made on the Wind Energy Converters (WEC) controller to make them capable of emulating inertial behaviour. Tests were performed in a multi-terminal DC network with two off shore wind farms to assess the feasibility and effectiveness of the concept in a communication-free framework.
2009
Autores
Pecas Lopes, JA; Soares, FJ; Almeida, PM; Moreira Da Silva, M;
Publicação
24th International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium and Exhibition 2009, EVS 24
Abstract
In this paper the behaviour of a Portuguese typical Low Voltage (LV) grid and the changes in the Portuguese global generation profile were analyzed, in a daily period, regarding different levels of Electric Vehicles (EVs) integration. The impacts provoked by EVs deployment on the network voltage profiles, branches' congestion levels, grid losses and imbalances between phases were evaluated using a three phase power flow. The first part of this work focused on the determination of the maximum share of electric vehicles, defined as the percentage of conventional vehicles replaced by EVs, which can be integrated into the selected grid, without violating the system's technical restrictions and complying with drivers' requests concerning the foreseen use of vehicles. The maximization of the EVs connected to the grid was performed using two distinct charging strategies: dumb charging and smart charging. The second task was to analyse the impacts of both charging approaches (dumb charging and smart charging) on the prevention of wasting renewable energy surplus. For the purpose of this analysis, a 2011 wet and windy day was considered, where large hydro and wind generation exists. For that specific case, in some periods of the day (mainly valley hours), the hydro and wind generation, added to the must run thermal generation units, will surpass the consumption and renewable energy can be wasted. The results obtained for the LV grid were extended to a National level and the changes in the Portuguese load/generation profiles were computed.
2012
Autores
Soares, FJ; Gouveia, C; Pereira Barbeiro, PN; Rocha Almeida, PM; Moreira, C; Pecas Lopes, JA;
Publicação
SMARTGREENS 2012 - Proceedings of the 1st International Conference on Smart Grids and Green IT Systems
Abstract
This paper provides a general overview of the initial developments in the REIVE project (Smart Grids with Electric Vehicles). The main focus of the project is on smart grid infrastructures for large scale integration of EV and micro-generation units. It is a natural evolution of the InovGrid project promoted by the EDP Distribuição - the Portuguese Distribution Network Operator - and allows the development of seminal concepts and enabling technological developments within the Smart Grid paradigm. This paper presents the management and control architecture developed to allow electric vehicle integration in smart grid operation. Additionally, it presents the major impacts in distribution grids of the simultaneous deployment of electric vehicles, micro-generation and smart grid technologies.
2012
Autores
Soares, FJ; Pereira Barbeiro, PN; Gouveia, C; Rocha Almeida, PM; Moreira, C; Pecas Lopes, JA;
Publicação
SMARTGREENS 2012 - Proceedings of the 1st International Conference on Smart Grids and Green IT Systems
Abstract
This paper describes the main results of the MERGE project relative to Electric Vehicle (EV) charging strategies and the impacts of EV integration on the steady-state grid operation. MERGE is a €4.5m, collaborative research project supported by the European Commission's Seventh Framework Programme (FP7). The consortium includes utilities, regulators, commercial organisations and universities with interests in the power generation, automotive, electronic commerce and hybrid and electric vehicle sectors across the entire European Union (EU). One of the MERGE project missions is to evaluate the impacts that EV will have on EU electric power systems, exploring EV and SmartGrid/MicroGrid simultaneous deployment, together with renewable energy increase, to achieve CO 2 emission reduction through the identification of enabling technologies and advanced control approaches. The work presented proposes three charging strategies, dumb charging, multiple price tariffs and smart charging, and uses EV integration scenarios of adherence to these charging schemes. The resulting scenarios are tested using an algorithm coded with Python and using PSS/E, created within the MERGE framework to study EU grids steady-state behaviour. Additionally, the critical mass of EV adherence to smart charging schemes that brings positive impacts to the distribution grids operation was also evaluated.
2011
Autores
Bessa, RJ; Soares, FJ; Pecas Lopes, JA; Matos, MA;
Publicação
2011 IEEE PES Trondheim PowerTech: The Power of Technology for a Sustainable Society, POWERTECH 2011
Abstract
It is foreseeable that electricity retailers for electrical mobility will be market agents. These retailers are electric vehicle (EV) aggregation agents, which operate as a commercial middleman between electricity market and EV owners. Furthermore, with the foreseen evolution of the smart-grid concept, these agents will be able to control the EV charging rates and offer several ancillary services. This paper formulates an optimization problem for the EV aggregation agent participation in the day-ahead and secondary reserve market sessions. Forecasting issues are also discussed. The methodology was tested for two years (2009 and 2010) of the Iberian market, considering perfect and naïve forecast for all variables of the problem. © 2011 IEEE.
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