Voltage control in low-voltage distribution networks in the context of introducing home charging stations for electric vehicles

Abstract

In this work, we investigate the effect of home charging stations for electric vehicles on voltage deviations in a 0.4 kV suburban distribution network. A 10/0.4 kV transformer substation and a 0.4 kV distribution network, supplying electricity to 114 private residential buildings, were selected as the research objects. In order to assess the effect of home charging stations on voltage deviations, a stochastic quasi-dynamic model of the electrical network was developed in the Python programming language using the Pandapower library. This model allows daily profiles of power consumption and voltage to be simulated at various numbers and connection points of home charging stations, taking the random behavior of electric vehicle owners into account. For maintaining the voltage level within the permissible limits, inverters for on-board chargers of electric vehicles in terms of reactive power sources and the shift of the charging start time to the night hours are considered. According to the simulation results, when 30% of 0.4 kV suburban distribution network consumers use a home charging station, the load on the main section of the supply line can briefly approach 100% and the depth of negative voltage deviations can exceed 20%. The Volt-Var control by on-board chargers of electric vehicles was established to reduce significantly voltage deviations in the distribution network (reducing the duration of voltage deviations below −5%, i.e., from 27.3 to 12.9%) with an insignificant effect on the charge duration of electric vehicles. The results obtained can be used in the long-term planning of distribution electric networks in the context of a widespread use of electric vehicles.