Behavioral Characterization of Electric Vehicle Charging Loads in a Distribution Power Grid Through Modeling of Battery Chargers

Abstract

The plug-in electric vehicle (PEV) is a new atypical load in power systems. In future, PEV load will play a significant role in the distribution grids. This integrated load into the power grid may overload the system components, increase power losses, and affect the voltage profile in the distribution systems. Currently, the constant power load model is most commonly used for the modeling of the electric vehicle (EV) load that considers the EV loads as constant power elements without considering the voltage dependence of the EV charging system. EV load demand cannot be considered as a constant power due to the fact that modeling as a constant power load will not provide accurate information about the behavior of the charging system during the charging process. In this paper, an accurate model representing the realistic behavior of EV load is developed which is based on the ZIP load model with the ZIP parameters established through the realistic EV load data. The proposed model can be used to analyze the true behavior of the EV charger integrated to an electricity grid and determine the impacts of EV charging load on the grid. A realistic charging system was used to test and capture the EV load behavior and extract the coefficients of the EV ZIP load model, which have been verified using computer simulations and laboratory experiments. Additionally, a comparative study between the proposed ZIP load model and the constant power load model was carried out, and the results were verified with the practical EV load data. The results confirm that EV represented using constant power load will not provide the true reflection of the EV load behavior and the EV impacts on the power grid.