Emergency control of DFIG-based wind turbines to meet new European Grid Code requirements

New regulatory requirements outlined in the European Grid Code dictate fault ride-through and reactive power support requirements for wind energy conversion systems. This paper introduces a simple emergency control scheme for DFIG-based wind turbines to comply with the grid code requirements. The proposed control design uses an enhanced phase locked loop (PLL) system to extract the synchronization signal from the three-phase grid voltage. The proposed PLL will also present an on-line estimation of the grid voltage magnitude, which is needed to detect the fault and provide the reactive power support accordingly. To increase the fault ride through capacity of DFIG, the standard PI current regulator in the rotor-side converter of DFIG is replaced with a vector-based hysteresis current regulator. The main advantages of the proposed current regulator are its very fast transient response and simple control structure. Simulation studies are carried out to demonstrate the effectiveness of the proposed emergency controller to comply with the new European Grid Code requirements under various network disturbances.