Power‐Quality Measurement and Assessment of Electric Vehicle Chargers for Grid Integration

The rapid adoption of electric vehicles (EVs) worldwide has introduced new challenges for power systems, particularly with respect to power quality and grid reliability. EV charging employs power electronic converters that behave as nonlinear loads, generating harmonic distortion, voltage fluctuations, and additional stress on distribution system components. This study experimentally investigates the harmonic characteristics of four commercially available EVs, namely, the FIAT EV, Nissan LEAF 2014, Nissan LEAF 2016, and Tesla Model 3, using detailed voltage and current harmonic measurements. The results show that voltage variations remain within international standards, whereas current harmonic distortion differs considerably among the investigated EVs. The Tesla Model 3 exhibits the lowest current total harmonic distortion (THD) of 6.64%, while the Nissan LEAF 2016 records the highest THD of 10.76%. The 3rd and 5th harmonics dominate the harmonic spectrum of most vehicles, with the Nissan LEAF 2016 producing the largest lower order harmonic components. Furthermore, increasing the charging level from slow to fast charging significantly reduces current THD from 10.76% to 3.15% and decreases the dominant 3rd harmonic current from 7.19% to 0.51%, resulting in improved power quality. Beyond conventional harmonic magnitude and THD assessment, harmonic voltage–current phase‐angle characteristics were investigated based on IEEE Std. 1459. The results reveal significant technology‐dependent harmonic behavior, with the FIAT EV exhibiting a 169° phase displacement at the 3rd harmonic, the Nissan LEAF 2016 showing a 155° phase displacement at the 3rd harmonic but only 5° at the 9th harmonic, and the Tesla Model 3 exhibiting its largest phase displacement of approximately 150° at the 9th harmonic. These results demonstrate that harmonic phase‐angle analysis provides valuable information beyond conventional THD measurements for identifying harmonic sources and evaluating harmonic power exchange in EV chargers. Although all tested EVs comply with the applicable IEC and IEEE harmonic limits individually, large‐scale EV integration may significantly increase cumulative harmonic levels, highlighting the importance of harmonic monitoring and phase angle–based assessment for future distribution networks.