Analysis on the exploitation of EV fast charging to prevent extensive grid investments in suburban areas

Fast charging of electric vehicles (EV) is assumed to affect the operation of electricity grids. In order to decrease the need for conventional grid reinforcement, energy legislators are increasingly motivated to design load-management incentives. Using the example of Germany, we investigate the extent to which voltage-control strategies decrease critical voltage levels in suburban low-voltage grids compared to uncontrolled charging. Voltage violations are identified by load flow simulation. Results showed that, for uncontrolled charging of 22 kW, each scenario except for EVs at the beginning of the line violated the voltage operation limit. Under these circumstances, the grid was operated within the voltage limits for 99.2 % of the year. Violations no longer occurred if active power limitation was performed. With reactive power control, full prevention of voltage-limit violation could not be achieved but the frequency of violations was reduced. A combination of both active power-limitation and reactive power reduced the volume and frequency of power limitation. In most cases, a power limitation of 2 kW satisfied the voltage boundaries. Thus, voltage control decreases the need for conventional grid reinforcement if grid operators gain more real-time information about the state of their distribution grids.