A low voltage ride-through control strategy of full power converter wind turbine system under balance grid fault

When the full power converter of wind generation system under the symmetry fault, for the first time by calculating the relationship between the current wind speed, rated wind speed, the drop depth of grid voltage and converter security to determine whether need for protection. If it need protect, precisely calculate the extra energy and increased by DC side Crowbar circuit of energy storage device, to across the symmetrical fault under the dip of grid voltage. In the period of the fault, according to the depth dip of the grid voltage injections reactive power to improve the voltage recovery. Simulation results show that at any wind velocity when the full power converter system of the wind generation under symmetrical fault, it can maintain the voltage of DC side constantly, according to the depth dip of the grid voltage injects reactive power to the net and it can achieve a low voltage ride-through.