Performance of a Variable Speed Double-Fed Induction Generator Wind Turbine During Network Voltage Unbalance Conditions

Usually the most productive sites for wind turbines and wind farms are in rural remote areas where distribution networks can be weak and voltage unbalance can be a common feature. Induction generators subjected to network voltage unbalance can overheat due to the excessive currents, and mechanical stress can occur due to torque pulsations. The rotor converter in a double-fed induction generator (DFIG) is also susceptible to high currents during periods of voltage unbalance. A DFIG wind turbine is modelled in the dynamic power system simulation program DigSilent to analyse the behaviour of both the induction generator and rotor converter to grid network voltage unbalance. The rotor converter in particular is analysed during network voltage unbalance conditions.