Residential harmonic loads and EV charging

TLDR

Large single‑phase residential harmonic loads, such as 6.6 kW EV chargers, can distort currents and threaten power‑quality and transformer performance on distribution systems. This paper examines the secondary distribution harmonic impacts of residential loads with and without EV charging. Simulations and field tests show that IEC‑compliant EV chargers do not raise transformer secondary voltage THD beyond 0.8 %, and off‑peak charging is recommended to further reduce impacts.

Abstract

The market penetration of large single-phase residential harmonic loads, including electric vehicle (EV) battery chargers of 6.6 kW, is a potential power quality and power delivery concern for electric power providers and consumers. Charging systems with high harmonic current distortion can potentially result in secondary distribution line and transformer de-rating or quality of service consequences. This paper reports on the main findings of a project that examined the secondary (customer-side) distribution harmonic impacts of residential harmonic loads, with and without EV charging. Simulations as well as actual field test site data, to determine the impact of residential single phase loads and EV charging systems on the secondary of the distribution transformer, show that-commercial EV chargers engineered to National Electric Vehicle Infrastructure Working Council (IWC) guidelines based upon IEC 1000-3-4 do not give rise to excessive voltage THD on the secondary of the transformer-the rise in voltage THD due to EV charging is less than 0.8% in all three field test sites and should not be a cause for concern. Load management strategies like off-peak charging should be encouraged to minimize the impacts on the distribution system.