Steady-State Analysis of Saturated Type IV Wind Turbines Under Non-Faulty Operations

The back-to-back converter connection of type IV wind turbine generators (WTGs) implies operational behaviors that differ from conventional synchronous generators. One difference is that type IV WTGs have injection limitations based on their converters’ capacity. During regular (non-faulty) operations, the WTG may saturate its converter’s capacity depending on the grid conditions, making it technically unfeasible for the WTG voltage to achieve the set reference. Such scenarios lead the WTG to new equilibrium points where the converter limitation determines the operation. This paper proposes a power flow approach to capture the described behavior and yield accurate steady-state estimations of saturated WTGs. The method leverages the computational advantages of a rectangular Newton-Raphson formulation for faster convergence. The obtained results indicate that the proposed methodology achieves estimations with errors below 1% in comparison to a field-validated EMT model.