CONTROLLABLE POWER BACKUP SYSTEM FOR WIND TURBINE

The present invention relates to a wind turbine comprising an internal power supply grid for distributing power to a number of power consuming units of the wind turbine, the wind turbine further comprising a power backup system connected to the internal power supply grid for supplying power to said internal power supply grid during a grid fault, wherein the power backup system comprises a controllable power storage module providing a total backup voltage that falls within a nominal voltage range of the internal power supply grid of the wind turbine. The present invention also relates to a power backup system and an associated method.