Robust Stability Analysis of Grid-Forming Converter-Dominated Grids Using Grey-Box Modelling Approach

In recent years, continuous efforts have been made for the modelling and stability analysis of converter-dominated grids. Ensuring stability in converter-dominated grids presents a unique challenge, primarily due to the manufacturers’ intellectual property (IP) protections. Determining the robust stability boundary of a grid incorporating converters from various manufacturers remains an area requiring extensive research. Recently, a grey-box modelling approach for studying interoperability has been proposed in the literature. However, the existing methodology is solely suitable for grid-following converters. This study bridges the gap by proposing a GFM converters model which aligns with the methodology for analysing the interoperability of GFL converters. The model is designed to represent a range of control system implementations across different manufacturers. Using robust control theory, this approach assesses the grid’s stability margin and sensitivity analysis of the control loops under various conditions considering a single GFM converter. The results are validated both analytically and through real-time hardware-in-the-loop (HIL) tests to demonstrate the model accuracy in predicting robust stability margin and sensitivity of the control loops in GFM converter-dominated grids.