Control of nonideal grid-forming inverter in islanded microgrid with hierarchical control structure under unbalanced conditions

Research on continued penetration of distributed energy resources (DER) from both power system and power electronics perspectives has been ongoing but the two approaches are largely exclusive of one another. This article aims to unite the two perspectives by using real-time simulation to model both the microgrid network and the individual grid-forming inverters responsible for supplying its power during islanded operation. Multi-scale simulations require fine-tuning of central control parameters, and similar care must be taken for transient durations relative to selected simulation step size. Instability can be introduced by lack of careful consideration of the aforementioned items, as well as unforeseen interactions between the selected inverter model and the larger microgrid model. Furthermore, model order requires appropriate attention to ensure a proper mix of simulation fidelity and stability. This work contributes a real-time simulation of a moderately sized network including state space models of typical grid-forming inverters, inclusive of nonidealities, and their associated controllers to demonstrate stability and performance in a microgrid featuring 100% photovoltaic generation penetration in islanded operation.