Grid support with hybrid GFL and GFM converter in Type IV wind generator

Wind turbine generators (WTG) use grid following (GFL) converter control, which can track its power reference (e.g., from a maximum power point tracking - MPPT - algorithm) quickly and accurately. On the other hand, grid forming (GFM) has better and faster grid support capabilities, which is especially relevant for power grids with low inertia. However, having two converters (one GFL and one GFM) in one WTG would be ineffective, especially in terms of cost. This paper proposes a single hybrid-controlled converter (HCC), which produces exactly the equivalent behaviour of the GFL and GFM converters in parallel. The HCC was applied to the grid-side converter of a Type IV WTG, which was modelled in PSCAD. Simulation results are presented to show the advantages of using HCC as part of the WTG control system. This approach aims to have a WTG that, in steady-state conditions, operates as a GFL converter guaranteeing MPPT, if its active power reference is the MPPT power, and during a disturbance in the grid, operates seamlessly as GFM providing frequency and voltage support, similarly to a synchronous generator. This project was supported by TotalEnergies.