In response to the challenge of economical harvesting of electrical energy and considering the environmental issues according to the Paris agreement for CO2 reduction, a key solution could be to integrate more and more distributed generators (DGs) and renewable energy sources (RESs) in the electric network. In this direction, in most countries, the capacity of installed inverter-based DGs/RESs in power grids is rapidly growing; and a high penetration level is targeted for the next two decades. However, recent studies have investigated that relatively high DGs/RESs integration will have some negative impacts on power grid dynamics, power quality, frequency control, voltage regulation, as well as other control and operation issues. In consequence, this challenge significantly limits the rate of renewable power penetration as well as overall system stability margin. Decreasing system inertia, increasing uncertainties and highly dynamic variable nature of distributed generators and renewable energy options are known as the main reasons. These impacts may increase for the dynamically week power grids at the penetration rates that are expected over the next several years. An idea towards stabilizing a grid with numerous distributed DGs/RESs is to compensate system inertia and weak dynamics, virtually. This may be established by a primary power source (e.g., DG or an energy storage) together with a smart controlled power electronics inverter/converter. This setup will then operate to emulate desirable dynamics, such as inertia and damping properties, by flexible shaping of its output active and reactive powers. This approach provides a promising solution to improve power grid stability and performance in the presence of a high penetration of DGs/RESs
