An Improved Control Strategy for GFM-based Control of Type-IV Wind Turbine Under Normal and Grid Fault Conditions

This study introduces an advanced control strategy tailored for Type-IV wind turbines, focusing on the coordination between the machine-side converter (MSC) and the grid-side converter (GSC) under grid-forming (GFM) control. With the growing penetration of wind energy in power systems, it is crucial for these systems to operate as voltage sources, ensuring stable terminal voltage and frequency by dynamically adjusting both real and reactive power outputs. Unlike conventional approaches, this paper presents a strategy where the MSC manages the DClink voltage, while the GSC operates under a newly proposed fault-ride-through mechanism, which involves freezing the power synchronous loop (PSL) during grid disturbances. Additionally, a novel current limitation mechanism is introduced to protect the converter during both balanced and unbalanced faults. Comprehensive simulation results in PSCAD/EMTDC validate the effectiveness of this control scheme under diverse grid conditions, including low short circuit ratios (SCR), balanced and unbalanced faults, and frequency variation scenarios.