Electric Vehicle Charging Management with Droop Control

Increasing residential electricity demand due to simultaneous charging of multiple electric vehicles (EVs) on the same feeder might lead to overloading of the distribution transformers as well as under-voltage at remote terminals of
the feeder. In this paper, two different droop control techniques have been proposed for EV charging management to mitigate such problems by reducing the charging load on the basis of droop factors corresponding to the terminal voltage deviation or transformer loading level. Such a control strategy reduces the feeder congestion and improves the terminal voltage at the feeder end. However, since the voltage drop increases as the distance from the substation is increasing, the customers located at the far end of the feeder will suffer from higher curtailment of the charging power in comparison to the customers who are connected closer to the sub-station. Thus, there will be disparity among the customers depending upon their distance from the sub-station and the customers at the far end of the feeder will face more restrictions, thereby limiting their benefit from the dynamic pricing of electricity. On the other hand, when the droop control is based on transformer loading level, a common factor
will be applied to all the EV charging loads on the feeder, so everybody will be equally affected.