With growing concern on climate change, widespread adoption of electric vehicles (EVs) is important. One of the main barriers to EV acceptance is range anxiety, which can be alleviated by fast charging (FC). The main technology constraints for enabling FC consist of high-charging-rate batteries, high-power-charging infrastructure, and grid impacts. Although these technical aspects have been studied in literature individually, there is no comprehensive review on FC involving all the perspectives. Moreover, the power quality (PQ) problems of fast charging stations (FCSs) and the mitigation of these problems are not clearly summarized in the literature. In this paper, the state-of-the-art technology, standards for FC (CHAdeMO, GB/T, CCS, and Tesla), power quality issues, IEEE and IEC PQ standards, and mitigation measures of FCSs are systematically reviewed. Index Terms-Charging stations, Electric vehicles, Power quality, Power system stability I. INTRODUCTION G ROWING concern about climate change intensifies the trend towards decarbonization and interest in clean technology. As a substitute for internal combustion engine vehicles (ICEVs), EVs powered by renewable electricity, can reduce petroleum usage and greenhouse emission [1], [2]. Besides, new technologies on the powertrain of EVs, e.g., wide-bandgap-component based motor drive that improves battery-towheel efficiency [3], make EVs more competitive on energy saving. The convenience of EV recharging significantly influences EV adoption and utilization. The charging power level is generally categorized into two classes-the slow charging and the FC. Typically, the former signifies the distributed charging at home, and public destinations, with the power rated lower than the maximum household power (e.g., 22 kW in European Union and 19kW in the United States [4]). On the contrary, fast chargers have a higher power rating and are typically used in FCSs. The charging modes are standardized in IEC 61851-1 [5] and SAE J1772 [1], according to the type of the input current (AC or DC) and the power level. In IEC 61851-1, four charging modes are defined, where Mode 1, 2, and 3 are the AC charging mode and Mode 4 is DC charging mode. Moreover, only Mode 3 and 4 support the FC. In SAE J1772, the EV charging is classified as three levels, where Level 1 and 2 are the slow charging via AC on-board chargers (OBCs), and Level 3 is the FC via DC off-board charger. Due to the space and weight constraints of the AC OBC, it has a limited maximum power rating, e.g., 43 kW for Mode 3 in IEC 61851-1. Thus, the mainstream FC is through the DC This project has received funding from the Electronic Components and Systems for European Leadership Joint Undertaking under grant agreement No 876868. This Joint Undertaking receives support from the European Union's Horizon 2020 research and innovation programme and Germany,

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The recent increase in large converter-based devices like electric vehicles and photovoltaics increases supraharmonic emissions in low-voltage grids, potentially affecting customer equipment and the grid. This paper aims to give an overview of the different factors influencing supraharmonic emissions from electric vehicles and studies the propagation of supraharmonic currents through a small, low-voltage grid. Measurements in an unique lab representing a possible future household gave valuable insight on the possible developments in primary and secondary supraharmonic emissions in a conventional or power-electronic-dominated system. Emission is, for some vehicles, influenced by the type of grid connection, whereas others show no difference in emission. The supraharmonic currents mainly stay within the local installation due to absorption of nearby devices. The level of voltage distortion is dependent on the connection impedance. During the measurements, another type of interaction between devices is observed in the form of “frequency beating” and intermodulation, in some cases resulting in the tripping of residual current devices. This interaction is further analyzed in order to better understand the possible impact it can have on the grid.

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This research investigates the effects of high frequency currents between 50 Hz and 150 kHz on the operation of Residual Current Devices (RCDs). Nowadays, the increasing amount of large power-electronic switching devices can be a source of both harmonics (<2 kHz) and supraharmonics (2-150 kHz) currents injected to the grid. This can have several effects and possibly lead to unwanted tripping of RCDs, due to high earth-currents that can be emitted by the devices. The question is if supraharmonics can also lead to misoperation or fail-to-operate conditions for the RCDs, potentially leading to serious safety risks. A set-up is developed to introduce both 50 Hz and highfrequency leakage currents. First, the 50 Hz tripping-current of the RCDs is tested under nominal conditions. Secondly, the tripping current for non-nominal frequencies (between 50 Hz and 150 kHz) is determined to verify the possibility for false tripping. Lastly, the 50 Hz tripping current for the RCD is tested in the presence of a high-frequency current. The most important conclusion is that RCDs of type A and AC have an increased fundamental (50 Hz) tripping current when there are HFcomponents present. This potentially results in a safety risk.

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