I. Introduction
The electrical power grid is going through a transformation of technologies and processes spurred by the deep proliferation of renewable energy sources, smarter control through increasing use of power electronic sources, and availability of high-fidelity measurement sources such as PMUs. Most of the developments in the electrical grid are emanating from the medium to low-voltage distribution grid. With progressively growing deployment of distributed energy resources (DERs), such as photovoltaics (PV), storage devices, electric vehicles, and microgrids, the characteristics of distribution systems are becoming more complex, both statically and dynamically [1]. Extensive work on load modeling has been carried out by power system researchers [2]–[5] to guide the development of load models through component-based [3], measurement-based approaches [6], [7], dynamic equivalencing [8]–[10], and neural networks [11], [12].