Grid voltage support during faults for dfig-based wind turbines

Abstract

The wind power penetration in the power system has already reached a considerate proportion. An important step in that path was the requirement of wind farms to provide Low Voltage Ride Through capability, remain connected to the grid during faults, and contributing to the stability of the power system. More recently, grid codes are also requiring wind turbines to inject reactive power during the fault event to contribute to grid voltage support. The purpose of this work is not only to analyze, but to propose a reactive current injection strategy for Doubly Fed Induction Generator based wind turbines that acts on the reactive power control loop during faults and, for severe cases, acts also in the grid-side converter to inject reactive current. The results of the simulations show, the behavior of the voltage, active power, the total current injected, and other electrical variables in the system for different connection characteristics. The reactive current injection strategy improves the voltage level during the fault, relieving the power recovery after the fault clearance due to the grid voltage enhancement.