Simulation study on low voltage operation of DFIG during grid three symmetric short circuit fault

When grid occurs short circuit fault and voltage drops, because of coupling relationships between stator and rotor windings of doubly-fed generator, over-current is generated in stator and rotor windings. At the same time, power that grid-side converter absorbs from the grid is out of balance from the power that rotor-side converter outputs, which makes redundant energy accumulated in DC-link and leads to over-voltage and under-voltage produced. Over-current may damage rotor-side converter and makes wind turbine detach from grids, and DC-link capacitance will be break down for the over-voltage. Therefore, it is necessary to adopt protection circuit to realize the low voltage ride through of DFIG system. In this paper, based on the established simulation model of DFIG, combination protection circuit composed of rotor-side Crowbar and DC-link protection circuit and it´s control strategy are researched during voltage drops for three symmetric short circuit fault of DFIG system, and simulated through Matlab/simulink software.