Voltage Dependent Load Models for EV Chargers to Improve the Accuracy of Grid-Impact Studies

Abstract

The emergence of electric vehicles (EV s) promises a sustainable future for the transportation sector. On the other hand, an extensive integration of EV s into electric grids could overload network equipment, amplify system losses, and induce voltage deviations. It is necessary to evaluate and account for the potential impact of EV proliferation on power systems to ensure their satisfactory operation. The reliability of such grid-impact studies is heavily influenced by the accuracy of load flow solutions. EV chargers are a relatively new load class to be incorporated into power flow studies. However, vehicle chargers are typically represented using the classical constant power load (CPL) model. The portrayal as a constant power operation that is unaffected by variations in the supply voltage does not reflect the battery recharging process exactly. The charging behavior of EV s can be represented more accurately using polynomial (ZIP) load models, which are capable of replicating the true relationship between power demand and grid voltage. In this paper, a voltage-dependent ZIP model that simulates EV charging realistically is utilized for power flow analysis and its results are compared with those of the CPL model in terms of system demand, energy loss and voltage magnitude.