Should we reinforce the grid? Cost and emission optimization of electric vehicle charging under different transformer limits

N.B.G Brinkel,W.L Schram,T.A Alskaif,I Lampropoulos,W.G.J.H.M Van Sark

doi:10.1016/j.apenergy.2020.115285

N.B.G Brinkel, W.L Schram + Show 3 more

Open Access

https://doi.org/10.1016/j.apenergy.2020.115285

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Journal: Applied energy	Publication Date: Jul 13, 2020
Citations: 111	License type: cc-by

Affiliation: Utrecht University

Abstract

With high electric vehicle (EV) adoption, optimization of the charging process of EVs is becoming increasingly important. Although the CO2 emission impact of EVs is heavily dependent on the generation mix at the moment of charging, emission minimization of EV charging receives limited attention. Generally, studies neglect the fact that cost and emission savings potential for EV charging can be constrained by the capacity limits of the low-voltage (LV) grid. Grid reinforcements provide EVs more freedom in minimizing charging costs and/or emissions, but also result in additional costs and emissions due to reinforcement of the grid. The first aim of this study is to present the trade-off between cost and emission minimization of EV charging. Second, to compare the costs and emissions of grid reinforcements with the potential cost and emission benefits of EV charging with grid reinforcements. This study proposes a method for multi-objective optimization of EV charging costs and/or emissions at low computational costs by aggregating individual EV batteries characteristics in a single EV charging model, considering vehicle-to-grid (V2G), EV battery degradation and the transformer capacity. The proposed method is applied to a case study grid in Utrecht, the Netherlands, using highly-detailed EV charging transaction data as input. The results of the analysis indicate that even when considering the current transformer capacity, cost savings up to 32.4% compared to uncontrolled EV charging are possible when using V2G. Emission minimization can reduce emissions by 23.6% while simultaneously reducing EV charging costs by 13.2%. This study also shows that in most cases, the extra cost or emission benefits of EV charging under a higher transformer capacity limit do not outweigh the cost and emissions for upgrading that transformer.

Highlights

With the substantial increase in electric vehicle (EV) charging transactions in low-voltage (LV) grids, optimization of the EV charging process receives growing attention
The results show that grid reinforcements to mitigate grid congestion caused by EV charging are in most situations not beneficial from both a cost and emission perspective; the additional costs and emissions in case of reinforcement outweigh the potential additional EV charging optimization benefits that can be obtained as a result of the higher transformer capacity
It was shown that the costs and emissions of grid reinforcements outweigh the benefits in costs and emissions in EV charging optimization resulting from increased grid capacity

Summary

Introduction

With the substantial increase in electric vehicle (EV) charging transactions in low-voltage (LV) grids, optimization of the EV charging process receives growing attention. Most EVs charge in an uncontrolled manner; the EV starts charging directly after connecting to the charging station, until its charging requirement is met. This charging strategy is generally regarded as undesirable, as a large share of. The authors want to thank Henk Fidder, Robin Berg and Bart van der Ree for their valuable input throughout the research process.

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