Control for voltage dips Ride-Through of Oscillating Water Column-based wave power generation plant equipped with Doubly-Fed Induction Generator

One of the main problems arising when dealing with Oscillating Water Column-based wave power generation plants equipped with Doubly-Fed Induction Generator, is the need of an adequate Fault-Ride-Through during voltage drops. In this paper it is proposed an innovative Fault-Ride-Through solution consisting of a control scheme that suitably coordinates the air flow control, the active crowbar and the variable frequency converter, fulfilling the Grid Code. Besides, the variety of cases presented due to different sea states (amplitude and frequency) and characteristics of the grid fault (voltage drop and fault period), makes necessary to adequately modify the references used by the controllers in order to achieve the desired Fault-Ride-Through capability. That is, the application of the same controller references for different sea scenarios, provoke different responses of the plant for the same type of grid fault. In the same way, the application of the same controller references to the plant working under the same sea scenario when a grid fault of different voltage drops occurs on the transmission system, causes different reactions in the wave power plant. In this sense, it has been also implemented a control that adapts the controller references according to the pressure drop and voltage reduction, improving the controllability of the active and reactive power and the Fault-Ride Through capability during voltage drops.