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Report RSE 17001238

Intelligent wallbox experimentation and development

Report

2016

Request Document (14.17 MB, .pdf)

D. Bertini (RSE SpA), C. Carlini (RSE SpA), P. Gramatica (RSE SpA)

EMOBILITY 2016 - Electric Mobility

The document explains the development and experimentation of a smart home wallbox with references about BMW i3 performance analysis for period 2015-2016 and new developments regarding charging mode (i.e. "flash") for public transportation vehicles and impact on distribution networks.

Most owners of electric vehicles using their home as a main charge so who has an electric car it will not get her always in charge every time you park in your garage or parking space. In this way, the car becomes a domestic load which should be considered when using major appliances especially if the contractual power is limited to 3 kW. It is therefore essential to use charging stations with adjustable current and maybe make the most of existing electronic meters ENEL release curves (1G).For the purpose was conducted an experiment to make smart a normal wallbox (home recharge station) with fixed or manual charge current limitation. The activity, conducted initially in the laboratory, consisted in the development of an automatic modulation of PWM signal and then communicating with the electric vehicle. The system is composed of three main software modules: one for server communication with the Wallbox, the second one for the logic control, and the last for the management control cycle. The hardware is composed by: the charging station, and 2 power meters – the first one placed immediately downstream of the fiscal electricity meter, and the second one upstream of the mains cable of the wallbox. The first phase of development of software modules simulating the consumption of the charge of the vehicle was carried out in order to optimize the timing of intervention (control cycle) in addition to the maintenance of average levels of power delegated to the control logic. In the second phase, real electrical vehicles were used to test their response to the PWM modulation. In parallel, collaboration was started with two electric vehicle charging stations manufacturer interested in the development of intelligent home devices that is able of managing charging taking into account the total consumption of the users. The evolution of charging devices during the course of tests carried out both in the laboratory and at real users has led to the creation of two products currently offered on the market.

The second part of the document summarizes the elaboration carried out on utilization data of vehicle BMW i3 over the 2015-2016 period, on the different types of route. The elaborations of nearly three years of use of the car showed that, after a battery life cycle of up to about 2000 km, fuel consumption has stabilized around the value of 130/140 Wh / km.

Some comparisons have also been made on the emission of CO2 with an equivalent internal combustion vehicle (diesel). The comparison shown an overall reduction of pollutant emissions in the case of the electric car; these reductions are more noticeable in summer periods while consumptions increase in winter months due to heating and use of headlights. However, if the electricity for the recharge is produced with conventional fossil sources, pollution will be likely associated to a Bulk Power Plant, equipped with dust, NOx and SOx abatement systems, and pollutants will be diluted on a larger territory. In case the electricity comes from renewable sources such as wind or photovoltaic, the CO2 emission is virtually negligible, remaining at the local level only the pollutants related to brakes and tyres.

The last part of the document summarizes the activity focused on the recharge of public transportation electric vehicles, which might have a considerable impact on distribution networks. In this context, many local administrations, with the aim of reducing traffic and improving air quality of cities, have introduced measures to limit the access of private motor vehicles to central areas; low-pollution vehicles (electric or hybrid) are usually exempted, together with public transport. For the scope of the activity, it has been considered a bus model based on "flash" recharging system (with a relevant expected impact on the electric distribution grid) as already experienced in the case of the city of Geneva (TOSA project). The document describes the methodology developed for the impact analysis of this new transport technology towards national electricity distribution networks, displaying it in a metropolis scenario and evaluating its potential replication. In order to gain greater significance in the analysis, we examine Local Public Transport Tracks linking urban areas close to peripheral historical centres, often hosting long-distance transport terminals (airports, AV stations, etc.). The choice of different transport lines will involve different distribution power networks, therefore dedicated analyses should be carried out.

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