Improved RSC-GSC decoupled and LVRT Control Strategies of DFIG-Based Wind Turbine

Presently, the wind power penetration has increased into the power grids, which implies that the influence of the wind turbine on the grid cannot be ignored anymore. The primary requirement of the grid codes is that the wind turbine must be stay connected to the grid at the time of voltage drops. That's why The Low Voltage Ride Through (LVRT) control technique is required. Wind turbines during any fault occurrence, have a significant effect on power system stability and reliability. In this work, the reactive current injection strategy is proposed between the rotor side and grid side converters of DFIG by determining the maximum output reactive current from both sides of above mentioned points to recover the grid voltage under different grid voltage sag levels. Based on the LVRT specification of wind turbine, the active power must be controlled to recover the steady state pre-fault value with the ratio 10% of the rated power variation at the stage of the grid voltage recovery. This paper also proposes an improved active current control instruction to achieve the active power recovery by controlling the rotor current component during grid fault mitigation operation. For validation of the improved controlled scheme, H87-2MW wind turbine prototype is used.