I. Introduction
In a traditional electrical grid, electrical power generated by large, centralized power plants is transmitted to end users using one-directional power flows. In recent years there have been many calls for the development of the so-called “smart electrical grid” (e.g., [1]–[3]) by expanding the traditional electrical grid with distributed, medium-scale renewables-based energy generation systems to better meet the increasing energy demand and environmental regulations. A “smart electrical grid” is expected to be more reliable, more energy efficient and more environmentally friendly. Specifically, it is possible to integrate distributed energy resources and generation systems, like wind and solar systems, into the electrical grid.