P. M. Rocha Almeida

Identifying management procedures to deal with connection of Electric Vehicles in the grid

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.

Using vehicle-to-grid to maximize the integration of intermittent renewable energy resources in islanded electric grids

This paper presents the results of a dynamic behaviour analysis study developed with the objective of quantifying the amount of wind power that can be 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 systems 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.

Electric vehicles participating in frequency control: Operating islanded systems with large penetration of renewable power sources

This paper addresses the problematic of operating isolated networks with large penetration of intermittent renewable power sources, as well as the benefits that electric vehicles might bring to these systems. A small islands network was used as case study and a 100% renewable dispatch for a valley period, only with hydro and wind generation, was tested in a dynamic simulation platform developed in Eurostag. Two distinct wind speed disturbances were simulated and, for both, the impact in the networks frequency was evaluated considering two different situations: electric vehicles only in charging mode and electric vehicles participating in primary frequency control. It was assumed the existence of 575 electric vehicles in the island. The impact of having electric vehicles performing primary frequency control in the expected batteries state of charge was also evaluated.

Advanced Metering Infrastructure functionalities for electric mobility

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.

A Monte Carlo method to evaluate electric vehicles impacts in distribution networks

This paper describes a statistical approach developed for assessing the impacts resulting from EV presence in a given electricity network was developed. The algorithm, developed for this purpose, is based on a Monte Carlo method and can be seen as a planning tool that allows obtaining average values for several system indexes, like buses voltages, branches loading and energy losses. Additionally, it also allows identifying the most critical operation scenarios and the network components that are subjected to more demanding conditions and that might need to be upgraded. The example of a small grid from one of the Azores islands, Flores Island, was used for illustration purposes and two scenarios of EV integration were considered: 25% and 50% of the current light vehicles fleet replaced by EV.

Quantification of technical impacts and environmental benefits of electric vehicles integration on electricity grids

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.

Grid interactive charging control for plug-in electric vehicles

This paper describes technical solutions to be adopted by Electric Vehicles (EV) battery grid interfaces, in order to get the provision of ancillary services to the grid. The developed solution exploits an EV battery charge control approach based in a grid cooperative response to frequency and/or voltage deviations. To be effective, those cooperative actions must result from both centralized/coordinated commands and local/individual EV charger response to the grid behaviour. In a scenario characterized by a massive deployment of EV, the adoption of such a solution allows an improvement on the power system dynamic behaviour, namely in small island grids.

Automatic Generation Control operation with electric vehicles

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.

Impacts of Large-Scale Deployment of Electric Vehicles in the Electric Power System

In this chapter, the most relevant results that were obtained from testing the approaches and algorithms developed in Chap. 6 are presented.

Electric Vehicles in Isolated Power Systems: Conceptual Framework and Contributions to Improve the Grid Resilience

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 systems 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.