Electrical Final year Project 2014

CHARGING OF PLUGIN ELECTRICAL VEHICLE--

Plug-in electric vehicles (PEVs) may guarantee significant advantages with respect to traditional gasoline-fueled vehicles in terms of:

• greenhouse gas emissions reduction;

• energy consumption reduction;

• air quality improvement;

• oil consumption reduction;

• higher drive comfort.

Owing to all these potentially significant societal benefits guaranteed by transport electrification, PEVs are expected to diffuse rapidly over the next few years.

Unfortunately, the resulting energy request for vehicle batteries recharging may create overload conditions for the electrical grid. It is then necessary to develop ad hoc strategies to manage the charging of these vehicles and consequently to adapt the grid infrastructure.

The project encourages you to cope with the very hot real-world problem arising from the increasing demand for charging Plug-in Electric Vehicles through the electrical energy distribution grid. You will analyze the effect of multiple quasi-contemporary charging requests on the grid, hence discovering how, as the number of users to be charged increases, either the grid collapses or the user requests may not be entirely fulfilled. You will be asked to analyze the effectiveness of smart energy dispatching strategies and smart battery charging methods in mitigating (or completely overcoming) the grid overload problems. You will also experience some of the real-world engineering trade-offs commonly encountered in developing scheduling strategies for the management of a shared resource such as the energy available from the grid.

A study by  the Pacific Northwest National Laboratory showed that the use of PEVs with the existing power plants in the U.S. could result in a 30% improvement in energy consumption per Vehicle Miles Traveled (VMT), a 27% reduction in CO₂ emissions, and a 52% reduction in imported oil [1]-[3].

Moreover, PEVs offer the unique possibility of being supplied by using clean renewable energy sources. According to a study of the Berkeley Center for Entrepreneurship & Technology of the University of California, the total emissions of the U.S. vehicle fleet would even be reduced by 62% by 2030 if about half of the fleet were powered by clean electricity. Owing to all these potentially significant societal benefits guaranteed by transport electrification, PEVs are expected to diffuse rapidly over the next few years. Indeed, electric vehicles are predicted to account for 64-86% U.S. sales of new light vehicles by 2030 [4].

Typically, PEVs require 0.2-0.3 kWh for a mile of driving and are characterized by battery capacity values in the range of 8-55 kWh. As a consequence, the additional demand for electric power required to charge a large fleet of PEVs in reasonable time may add a significant load to the distribution grid. For example, a study of the Joint Research Centre of the European Commission carried out for a real case study has recently shown that the maximum electric power request would increase by about 30% if PEVs should reach 25% of the vehicle fleet [5].

In a similar scenario, the presence of several contemporary charging requests could cause overload conditions in local nodes of the grid if the charging processes of the PEVs are not properly managed and scheduled. These overloads might lead to interruptions and/or unbalanced conditions which may degrade the quality of service, increase line losses and damage utility and customer equipment [3], [5].

It is therefore mandatory to develop innovative strategies for the scheduling of the battery charging process to avoid dangerous grid load conditions. Unfortunately, both electrical distribution grids and charging systems available nowadays are essentially “dumb” structures that offer no (or very poor) interacting capabilities. Thus, at the present time, the only possible working modality is to start the charging process of a PEV just when the vehicle is plugged in (or, at most, with a delay fixed by the user) without any dynamic adaptation mechanism of the charging conditions to the actual grid load. Clearly, the actual implementation of innovative strategies to overcome the problems discussed will require the combined development of smart grid infrastructures and advanced charging systems capable of reciprocal interaction. Only pursuing this multifaceted “smart revolution”, in which the engineers’ contribution is fundamental, it will be possible to support PEVs diffusion and to benefit from the potential huge advantages deriving from their extensive penetration worldwide.