Modeling and Forecasting of Self-Similar Power Load Due to EV Fast Chargers

In this article, we consider modeling and prediction of power loads due to fast charging stations for plug-in electric vehicles. The first part of the project is to simulate work of a fast charger activity by exploiting empirical data that characterize EV user behavior. The second part describes the time series obtained by this simulator and its properties. We show that the power load aggregated over a number of fast chargers (after deseasonalizing and elimination of the linear trend) is a self-similar process with the Hurst parameter 0.57 ¡ H ¡ 0.67, where H varies depending on the multiplexing level. The main contribution of the paper is empirical evidence that a fitted fractional autoregressive integrated moving average (fARIMA) model taking into account self-similarity of the load time series can yield high quality short-term forecasts when H is large enough. Namely, the fitted fARIMA model uniformly outperforms regular ARIMA algorithms in terms of root-mean-square error for predictions with time horizon up to 120 minutes for H greater than or equal to 0.639. Moreover, we show that the fARIMA advantage on average grows as a function of the Hurst exponent H. Computational experiments demonstrate that this edge is stably greater than 1.1% and can be as high as 57% for some scenarios. 2015 IEEE Transactions on Smart Grid This work may not be copied or reproduced in whole or in part for any commercial purpose. Permission to copy in whole or in part without payment of fee is granted for nonprofit educational and research purposes provided that all such whole or partial copies include the following: a notice that such copying is by permission of Mitsubishi Electric Research Laboratories, Inc.; an acknowledgment of the authors and individual contributions to the work; and all applicable portions of the copyright notice. Copying, reproduction, or republishing for any other purpose shall require a license with payment of fee to Mitsubishi Electric Research Laboratories, Inc. All rights reserved. Copyright c © Mitsubishi Electric Research Laboratories, Inc., 2015 201 Broadway, Cambridge, Massachusetts 02139