Dynamic Virtual Resistance Control of Doubly Fed Induction Generator during Grid Faults

With the vigorous development of renewable energy, wind power accounts for a higher proportion of power systems, so wind power generation must have a certain low voltage ride through capability. This paper first establishes a transient mathematical model of doubly-fed wind turbines under grid voltage symmetrical drops, and analyze the transient characteristics of DFIG. A dynamic virtual resistance control strategy is proposed for the case of over-voltage and over-current on the rotor side of the DFIG under grid faults. The control method can suppress the oscillation of the current component on the rotor side and improve the transient stability of the DFIG. The resistance of the virtual resistor will change with the voltage drop and it can better meet the synergistic suppression of the rotor side electrical stress under different conditions. The simulation of a 2-MW DFIG in DIgSILENT well demonstrates the enhanced capability of DFIG to ride-through symmetrical faults.