Islanding operation for DFIG based wind farm

With the more substantial large-scale wind integration projects implemented in the province of Alberta, wind power has been growing steadily in the province to meet the increasing consumer demands. Meanwhile the transmission and distribution networks are being updated to satisfy the transmission capacity. Under the transmission line and substation construction with planned transmission line outages, it may expose the wind farm with radial connected with the main grid. The contingency plan usually has the anti-islanding protection scheme activated that will trip off wind farm and result in the loss of supply for the load in the island. This paper explores the method that the DFIG typed wind farm can survive with autonomous frequency control for islanding operation in a short term period without any energy storage devices. DFIGs synchronize to form a reliable wind farm frequency source which does not collapse when member DFIGs fail. The frequency enables frequency droop control to be implemented for load sharing and maximized the critical load online time in the island. The paper identifies that at the instant of islanding the excess wind power can accelerate the wind turbine-generators beyond their safe speed limit to be a critical problem. This problem can be solved when the designed turbine-pitch angles control method applied.