Current-type power hardware-in-the-loop interface for black-start testing of grid-forming converter

Grid-forming converter establishes a stable and controllable voltage at its output terminal without requiring external angle reference, which enables the GFC to be a candidate for providing black start services. However, this attribute poses significant challenges to the conventional power hardware-in-the-loop (PHIL) simulation, which incorporates the physical power converter by regulating its voltage angle to be synchronized with that of an interfacing power amplifier mimicking the real-time emulated power grid. The lack of voltage synchronization at the coupling point of GFC and interfacing power amplifier leads to instability. To address this challenge, the current-type interfacing method with compensation and scaling scheme is proposed to interface a GFC with soft black-start capability into a PHIL setup. Analytical assessment and experimental results involving interfacing a 90 kVA power converter implemented with grid-forming control are presented to verify the methodology.