Harmonic Emission of EV Fast Charging Station under Different Supply- and Operating Conditions

Both the number of electric vehicles (EVs) and corresponding fast-charging stations (FCSs) are developing rapidly. FCSs are large power electronic (PE) devices and can influence the harmonic distortion levels in the grid. FCSs can operate under a broad range of operating conditions, depending on, for instance, the type of EV connected and the state of charge of the battery and this might influence the characteristic harmonic emission. Furthermore, harmonic voltage distortion can result in additional harmonic current emissions from the devices. As there is no normative method yet to characterize the harmonic emission from FCSs under different operating conditions, it is unknown how they impact the grid in practice. In this research, a comprehensive analysis of the harmonic emission of an FCS under different supply voltage- and operating conditions is provided. A test set-up is developed that allows the definition of the charging parameters and the supply voltage, resulting in a so-called harmonic fingerprint of the FCS. The most impact on the harmonic emission is observed from the DC output power and the DC output voltage. Also, some cross-correlation between harmonics is observed. The findings are useful for modeling purposes and support the assessment of the impact of FCSs on the distribution grids.