Transmission-Distribution Dynamic Co-simulation of Electric Vehicles Providing Grid Frequency Response

This paper investigates the impacts of electric vehicles (EVs) on power system frequency regulation based on an open-source transmission-and-distribution (T&D) dynamic co-simulation framework. The development of an EV dynamic model based on an Western Electricity Coordinating Council dynamic model is introduced first, then the T&D dynamic co-simulation platform is described. The advantage of the overall platform is that distributed energy resources, such as distributed photo-voltaics and EVs, are modeled explicitly in both transmission and distribution simulators for frequency and voltage dynamics, respectively. The case studies simulate the frequency responses (i.e., primary and/or secondary) of the EVs after the system is exposed to an N-1 contingency, such as a generation trip. Various EV frequency regulation participation strategies are also investigated to study their impacts on system frequency response. The studies shows that EVs have the potential capability to provide effective frequency regulation services.

I. Introduction

Many countries have set goals toward or are planning to reach a carbon emissions-free power sector and to reduce carbon emissions of the transportation sector during the next two decades. As a result, an increasing number of electric vehicles (EVs) and charging infrastructure will be deployed in the transmission and distribution networks. Because inverter-based resources-such as EVs, distributed photovoltaics (DPV), and energy storage-are connected to the grid through power electronic devices, the total inertia of the system is decreasing and making the system more vulnerable to frequency fluctuations [1]. Different control strategies for the generation units and storage can be adopted to restore the frequency response by providing real power support [2], [3]. These frequency regulation services, including both primary frequency response (PFR) and secondary frequency response (SFR) [4], can balance the system total load and generation.