Power quality assessment of current electrical vehicle charging processes

The penetration of electrical vehicles (EVs) has an impact not only in the presumably increasing electrical demand, but also on power quality (PQ) of low-voltage (LV) radial distribution systems (RDSs), specifically in the harmonic current emission. Thus, it is essential that EV battery charging system designers should be aware of the potential impact of their designs on harmonic emission. Since the effect of charging systems on RDSs is not merely the numerical sum of total harmonic distortion (THD), harmonic phase cancellation may take place, harmonic phase angles should be also investigated. A theoretical background description on harmonics allowed us to perform a suitable campaign of harmonics measurements. Ten sets of measurements were performed on complete charging cycles of two different types of EVs. The results included the statistical characterization of individual harmonic current distortion and phase angle in order to account for randomness during the charging process.