Grid-forming control and operational strategies for offshore wind turbines incorporating electrical and mechanical modelling

This paper presents the modelling and grid-forming controls for Type 4 offshore Wind Turbine Generators (WTGs). It seeks to highlight relevant properties of the controls and the operational strategies that are used in the context of the research project “Offshore Wind Farms as Power Plants” (“OffWiPP”). In the addressed project, the depicted WTGs are combined with a newly controlled High-Voltage Direct Current (HVDC) transmission system, which also utilizes a grid-forming control in the onshore converter station and, therefore, provides system services at the onshore grid connection point with the aid of the wind turbines. Furthermore, an overcurrent limitation strategy is implemented, which similarly works for balanced and unbalanced low-voltage faults and phase-angle steps in the grid.