Control Method of a Doubly-Fed Induction Generator with a Grid Synchronization Against Parameter Variation and Encoder Position

In order to transmit energy generated through the stator winding of a doubly-fed induction generator (DFIG), we need to synchronize the generated voltage vector with the grid voltage vector. However, the existing synchronization methods work only when the encoder is installed at a specific position and equivalent constant is precise. In order to solve these problems, a new synchronization method has been proposed and a way of applying the method to existing doubly-fed induction generator control algorithm has been also suggested. The validities of the methods proposed were verified by using a prototype converter for a 500 kW-class doubly-fed induction generator and experimental results showed the validity of that against variation of an encoder positions, generator parameters, and grid voltages.