Current harmonics of EV chargers and effects of diversity to charging load current distortions in distribution networks

Charging of electric vehicles (EVs) is expected to bring a healthy addition of load for the distribution networks. The residential networks where the EV owners would charge their vehicles after returning from daily activities would especially be subjected to high load increase. As EV charger is a powerful nonlinear load rather large harmonic currents can be present during the EV charging. This means a significant increase also to the current harmonics. Analysis of the quantities of the harmonic currents is necessary for guaranteeing the distribution network operation that would meet the power supply standards. In this paper, the EV charging measurement results are presented and analyzed with focus on the current waveform distortions. Different EVs are analyzed for the current harmonics present during the slow rate home charging. For the modeling of the EV charging loads in the networks, discussion is presented on the harmonic currents summing and cancellation effects. The results presented in the paper can be further used for modeling of the actual harmonic loads of the EVs in the distribution networks.