On Performance and Compliance of Grid-Forming Assets

Abstract

The transition towards renewable energy integration poses significant challenges for maintaining grid stability, particularly as conventional synchronous machines are displaced by inverter-based resources. Grid-forming (GFM) converters have emerged as a promising solution, as they can replicate key system support functions such as voltage and frequency regulation, inertia provision, and fault ride-through. This thesis investigates the grid code compliance requirements for GFM assets and evaluates the performance of battery energy storage systems (BESS) and wind turbines (WT) when operated in GFM mode.

To investigate this, two of the most prominent GFM control approaches, Droop Control and Virtual Synchronous Machine (VSM) control, were selected and modeled in DIgSILENT PowerFactory. The standard GFM control library was extended with customized controllers to represent both BESS and WT. Among the available compliance frameworks, the AEMO grid code was chosen as the reference, as it defines clear test protocols and provides detailed simulation models for evaluating GFM performance. The developed models were then subjected to a series of compliance tests under this framework, including frequency ramps, weak grid operation, voltage and fault disturbances, and synchronous machine disconnections.

The results show that both BESS and WT can achieve compliance, but with differing characteristics. BESS consistently demonstrated strong and robust performance across all tests, with VSM control providing faster stabilization and better damping compared to Droop. WT also complied with most requirements, but their performance was more sensitive to weak grids and large disturbances. This thesis concludes that GFM converters are essential for future power systems with high renewable penetration. BESS offer reliable compliance across grid codes, while WT require careful tuning and system support.