Simulation of Grid-Forming Inverters Dynamic Models using a Power Hardware-in-the-Loop Testbed

Modern power grids include a variety of renewable Distributed Energy Resources (DERs) as a strategy to comply with new environmental and renewable portfolio standards (RPSs) imposed by state and federal agencies. Typically, DERs include the use of power electronic (PE) interfaces to interact with the power grid. Recently this interaction has not only been focused on supplying maximum available energy, but also on supporting the power grid under abnormal conditions such as low voltage/frequency conditions or non-unity power factor. Over the last few years, grid-following inverters (GFLIs) have proven their value while providing these ancillary grid-support services either at residential or utility scale. However, the use of grid-forming inverters (GFMIs) is gaining momentum as the penetration-level of DERs increases and system inertia decreases. Under abnormal operating conditions, GFMIs tend to better preserve grid stability due to their intrinsic ability to balance loads without the aid of coordination controls. In order to gain and propose fundamental insights into the interfacing of GFMIs to real time simulation, this paper analyzes the dynamics of two different GFMI simulation models in terms of stability and load changes using a Power Hardware-in-the-Loop (PHIL) simulation testbed.