The paper concerns with increasing wind turbine availability by avoiding the shut-down under generator stator insulation degradation. Field-oriented control algorithm is derived
for the wound rotor synchronous generators in wind turbine and further extended to achieve safe operation in the stator fault presence. The fault-tolerant control restricts the magnetic flux time derivative and thereby the stator voltage, which is the main cause for rapid fault development in the degraded stator insulation conditions. The method ensures maximum power production and wide wind turbine operation for different developed fault stages. The algorithm is set for the case of 700 kW wind turbine
with direct-drive wound rotor synchronous generator but can be applied for any other type of generator as well.