Impact of Harmonic Distortions Due to Scaled EV Charging in Residential Distribution Cable Systems Considering the Filtering Effect of Distribution Cable π Structure

The number of electric vehicles (EVs) has rapidly grown over the last decade, and their charging loads have caused a significant impact on the cable capacity of the power system. The effect of the EV charging load on cables would be overestimated with harmonics and underestimated without harmonics. To accurately evaluate the impact of EV charging loads on the cable capacity of the distribution system, this paper presents a cable model considering the cable inductance and capacitance filtering effect and a methodology to solve the harmonic power flow in the distribution system. Then, the maximum penetration of EV under the constraint of system voltage and current and the maximum allowable temperature of cable insulation is calculated. An IEEE-33 node distribution system is adopted as an example. The total number of vehicles in the distribution system is assumed to be 2300. Results show that the LC filtering effect of cables can reduce the harmonic voltage and harmonic current above 29th by more than 99% when the penetration of EV is 20% and 6.6 kW single-phase uncontrolled rectifiers are used. The LC filtering effect of the cable can be disregarded when charging with Pulse-Width Modulation (PWM) rectifier chargers. The method improves the accuracy of cable capacity assessment by EV charging loads.