Assessment of Harmonic Emission from Electric Vehicle Charging and their impact on Distribution Grid Quality

As charging power and charger density continue to grow, understanding how these harmonic emissions behave under everyday operating conditions has become important for assessing the hosting capability of existing LV assets and for ensuring compliance with international powerquality limits.

In this work, a measurement-based approach is used to study harmonic behaviour during gridto-vehicle (G2V) charging. Harmonic magnitudes and phase angles obtained from controlled 20 kW direct current (DC) fast-charging tests are used to reconstruct three-phase current waveforms up to the 50th order, which are then applied to a detailed 20 kV/0.4 kV Finnish feeder model with frequency-dependent transformer and cable impedances. This combination of laboratory data and feeder-level simulation makes it possible to examine how realistic charger spectra influences network distortion. The study evaluates current and voltage total harmonic distortions (THDᵢ, THDᵥ), total demand distortion (TDD), and neutral-current behaviour for different charging combinations. Simulated results follow the same trends observed in the measurements, giving confidence in the reconstructed injections. For single-charger operation, THDᵢ ranges between 6 % and 12 %.

When several chargers operate at the same node, the 5th and 7th harmonics become more pronounced and neutral current increases, particularly during simultaneous energisation. THDᵥ remains below the 8 % EN 50160 limit, and transformer TDD, based on a short-circuit ratio of roughly 475, stays within the 15 % IEEE 519-2022 requirement.

The results show that phase-angle alignment between chargers plays a key role in whether harmonics reinforce or cancel, while neutral current rises due to triplen components. Overall, the validated playback approach offers a practical tool for examining harmonic hosting capacity and checking compliance at the point of common coupling (PCC). For the studied Finnish LV feeder, up to six 20 kW chargers can operate simultaneously without sustained violations of harmonic standards, supporting reliable, power-quality-compliant fast-charging integration.