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Publications

Publications by CPES

2009

The new role of substations in distribution network management

Authors
Madureira, A; Lopes, JP; Carrapatoso, A; Silva, N;

Publication
IET Conference Publications

Abstract
This paper presents a novel architecture for electrical distribution networks based on a decentralized control system where a Substation Automation and Control System plays a key role. This new control element brings additional control and management functionalities that are crucial for future distribution networks with high levels of Dispersed Energy Resources in both interconnected and islanded operating modes. Several coordination and control issues are addressed with the aim of optimizing grid operation in interconnected mode and simulation results are shown for voltage and reactive power control.

2009

Identifying Management Procedures to Deal with Connection of Electric Vehicles in the Grid

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

Publication
2009 IEEE BUCHAREST POWERTECH, VOLS 1-5

Abstract
This paper describes a research developed to identify management procedures to deal with the charging of Electric Vehicles (EVs) batteries in scenarios characterized by a large scale deployment of this new kind of load. Three approaches were studied: dumb charging, dual tariff policy and smart charging. To assess the efficacy of such procedures, the grid integration of EVs was pushed to its limit for each of the adopted charging management approaches. A Medium Voltage (MV) grid, representative of a residential area distribution grid in Portugal, was used as testing environment. Several shares of EVs technologies were considered for different integration scenarios. Voltage profiles and branch congestion levels were evaluated, for the peak load hour, for grid technical limits checking. Losses were also evaluated for a typical daily load profile.

2009

Using Vehicle-to-Grid to Maximize the Integration of Intermittent Renewable Energy Resources in Islanded Electric Grids

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

Publication
2009 INTERNATIONAL CONFERENCE ON CLEAN ELECTRICAL POWER (ICCEP 2009), VOLS 1 AND 2

Abstract
This paper presents the results of a dynamic behaviour analysis study developed with the objective of quantifying the amount of wind power that can he safely, integrated in an isolated electricity grid where Electric Vehicles (EVs) are present. The assessment was performed considering two distinct situations: a) when EVs are only, in charging mode and b) when EVs participate in primary frequency, control. The test system, a small island, contains, in addition to wind generation, a small amount of solar PV plants and four conventional diesel generators. Only wind power influence in system's frequency, was assessed since, from a dynamic perspective, this is the renewable resource whose high intermittency level might be more harmful for the electric system operation. Sudden wind variations were simulated and, for both situations, a) and b), the amount of Intermittent Renewable Energy Sources was maximized, keeping always the grid frequency, within the limits defined by: the power quality standards.

2009

Quantification of Technical Impacts and Environmental Benefits of Electric Vehicles Integration on Electricity Grids

Authors
Pecas Lopes, JAP; Soares, FJ; Rocha Almeida, PMR; Baptista, PC; Silva, CM; Farias, TL;

Publication
2009 8TH INTERNATIONAL SYMPOSIUM ON ADVANCED ELECTROMECHANICAL MOTION SYSTEMS (ELECTROMOTION 2009)

Abstract
In this paper a typical electricity distribution network for a residential area in Portugal is used in order to assess the impact of integrating different levels of pure electric vehicles and plug-in hybrid vehicles in the grid and in pollutants emissions. First, the amount of vehicles that can be safely accommodated in the grid will be determined. Second, changes in pollutants emissions will be evaluated, by applying a vehicle full life cycle analysis.

2009

Coordinated voltage support in distribution networks with distributed generation and microgrids

Authors
Madureira, AG; Pecas Lopes, JAP;

Publication
IET RENEWABLE POWER GENERATION

Abstract
This paper proposes a new methodology for coordinated voltage support in distribution networks with large integration of distributed generation and microgrids. Given the characteristics of the LV networks, it is shown that traditional control strategies using only reactive power control may not be sufficient in order to perform efficient voltage control. Therefore, microgeneration shedding must also be employed, especially in scenarios with extreme microgeneration penetration. An optimisation tool based on a meta-heuristic approach was developed to address the voltage control problem. In addition, neural networks were employed in order to decrease computational time, thus enabling the use of the tool for online operation. The results obtained revealed good performance of this control approach.

2009

An optimization approach for wind turbine commitment and dispatch in a wind park

Authors
Moyano, CF; Pecas Lopes, JAP;

Publication
ELECTRIC POWER SYSTEMS RESEARCH

Abstract
This paper describes an operational optimization strategy to be adopted at the wind park control level, that enables defining the commitment of wind turbines and their active and reactive power outputs following requests from wind Park Dispatch Centers, assuming that individual wind turbines short-term wind speed forecasts ate known and are expressed as power availability. This operational strategy was also developed with a concern on the minimization of the connection/disconnection changes of the individual wind generators. fora given time horizon. When identifying the active/reactive dispatching policies, wind generators loading capabilities are also taken in account. This optimization tool is especially suited to manage large wind parks.

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