Co-ordinated voltage control strategy for a doubly-fed induction generator (DFIG)-based wind farm

The penetration of wind power into electricity networks is increasing and many large wind farms use doubly-fed induction generator (DFIG) based wind turbines. A voltage control strategy for a DFIG-based wind farm is essential for compliance with some wind farm connection requirements. Such a control strategy may also have commercial benefits. This paper presents a voltage control strategy and illustrates the advantages of this methodology when applied to a DFIG implemented wind farm connected either to a transmission system or embedded within a distribution system. Dynamic linear time invariant models of the DFIG including its associated voltage source convertor and controllers are derived in the synchronous d–q reference frame. In addition, the local on-load tap changer is modelled as a finite state machine and the co-ordinated controllers for both systems are described. Simulation results are presented to illustrate the effectiveness of the controllers within both a transmission system and a distribution system.