Enhanced fault ride-through control for grid-forming inverters: comparative analysis and adaptive strategies

As renewable energy technologies increasingly dominate as primary power sources, grid-forming (GFM) inverters have emerged as crucial components for future low inertia power systems, offering flexible inertia support and autonomous grid-forming capabilities. However, their integration poses significant challenges, especially in maintaining fault ride-through (FRT) capabilities, which are constrained by the inverters’ limited overcurrent capacity. This paper evaluates three distinct FRT strategies for GFM inverters: additional power control, direct current injection, and switching-following-type control. By establishing energy functions for each strategy, the transient stability is thoroughly analyzed, and the influence of key parameters is systematically investigated. Theoretical analysis and simulations are conducted to examine the impacts of control parameters and fault voltage sag depths, providing insights into system behavior under diverse fault conditions. To further enhance the FRT performance, an adaptive reactive power coefficient and enhanced multi-mode FRT control are proposed to maximize the inverter’s active support capability and achieving improved fault response under various voltage sags and swells. The effectiveness of the proposed control scheme is validated through extensive simulations using PSCAD/EMTDC.