Grid-forming control: identification through benchmark and hardware-in-the-loop testing

The integration of renewable power sources results in more converter-based generation in the grid. To enable a future stable power grid these converters, have to implement control software able to stabilize the power grid during different fault situations. This leads to grid codes for the grid-forming (GFM) control principle, superior to the today mostly used grid-following (GFL) controls. This paper proposes a test method for the identification of the converter’s control based on the performance after different disturbances (e.g. small voltage magnitude jump, voltage phase jump, etc.) without any detailed information from the controller itself. For this purpose, representative controls are implemented in a Power Hardware-in-the-Loop environment and compared with ideal constant current and voltage sources performance. The results demonstrate that system responses, such as for voltage magnitude jumps, can feasibly estimate control implementation and provide insights into voltage control loop usage. Conversely, voltage phase jumps reveal differences in the synchronization methods, with GFL unable to inject additional active phase jump power. These findings validate the proposed methodology for distinguishing between grid-following and grid-forming controllers based on measurements in a Power Hardware-in-the-Loop setting.