Impact of Electric Vehicle Charging on The Power Grid

This report summarizes the situation with knowledge and challenges regarding the large-scale introduction of electromobility in the Swedish power grid. The content covers a range of systemic perspectives in terms of challenges and impacts that the fast-growing amount of charging associated with electromobility poses to the actual power system. From this, several important questions are addressed in order to predict the future positive and negative impacts of this. The focus is placed on the possible impacts on the low and medium voltage networks, mainly exploring the power quality issues and grid hosting capacity. The following power quality issues are addressed: RMS voltage (slow voltage variation, overvoltage, undervoltage, fast voltage variations), unbalance, waveform distortion (harmonics, interharmonics, and supraharmonics), and power system stability. The hosting capacity is examined to predict whether the charging demand from electromobility can be accommodated in the existing power system considering the involved challenges. Furthermore, the aspect related to the charging process and people’s traveling patterns under a stochastic point of view is analysed. With the advantages that electromobility brings, it is noticeable that people will change the way they move around. Insights from this perspective make it possible to predict how the grid needs to change to accommodate future needs. From the found evidence in this report, it is noticed that the harmonic content of the current injected from electric vehicle charging is not negligible, though its magnitude is low it may get aggregated with harmonics produced by other connected loads in the low voltage network. Additionally, the results from leakage current (due to supraharmonics) in protective earth, light flicker and voltage dip studies show potential issues due to the charging process. Further, this study determines the hosting capacity of EVs based on the PV – EV integration, dynamic line rating, curtailment (hr/yr) of large rated electric vehicles and temperature. The hosting capacity studies estimated a significant surplus capacity for EV penetration under the present grid condition in Sweden. But considering a certain level of risk especially during winters proper planning is required. Other evidence from this report provides additional support for future discussions and debates regarding the impacts of electromobility on the electrical system.Swedish Energy Agency (“Energimyndigheten”) project entitled “Interaction between charging infrastructure with electromobility and the electricity grid