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To achieve sustainable solution and greener future, integration of renewable energy sources (RES) to the electric grid has gained favorable attention in the past few decades. Presently, most of RES are connected to the grid through the traditional current-controlled grid-following inverter (GFLI). However, with high RES penetration to the grid, new challenges exist such as voltage/frequency regulation and reduction of system's overall inertia, which cannot be addressed by using conventional GFLI. Due to that, the idea of the voltage-controlled grid-forming inverter (GFMI) was adopted. This paper discusses the concept and control of GFMI in which renewable energy resources are utilized to form the power grid. In this paper three different control methodologies are investigated namely, droop control, virtual synchronous generator (VSG) control, and Synchronverter control, where their dynamic performance is compared in terms of frequency trajectory, settling time, and amount of change in the frequency under a sudden load change in a standalone ac system. A system case study was implemented in a MATLAB/Simulink environment, where the results are illustrated and analyzed. The results validate that both VSG and Synchronverter techniques are able to provide virtual inertial support to the system, whereas we can observe the absence of this feature in the droop control approach.
Ali et al. (Wed,) studied this question.