Novel crowbar system in doubly fed induction generators

Nowadays, grid code requirements demand that wind energy converters (WEC) remain connected to the grid during grid faults and contribute to the voltage support, in the same way as conventional power plants. WEC which are capable of ridding through grid faults providing voltage and reactive power support are connected to the grid via electronic power converters, increasing the failure risk and reducing the reliability due to the negative influence of cosmic radiation on semiconductors. Doubly fed induction generators (DFIG) are widely used for wind power generation, fulfil low voltage ride through (LVRT) requirements and need a power converter for only 30% of the rated generator capacity, reducing the chip area and increasing the operation reliability. The crowbar protection is indispensable to avoid the disconnection of DFIG during grid faults and the damage of the rotor side converter. This work analyses the crowbar operation according to the grid code requirements and presents a novel crowbar system.