Fault-Ride-Through Capability of Oscillating-Water-Column-Based Wave-Power-Generation Plants Equipped With Doubly Fed Induction Generator and Airflow Control

The increasing use of distributed power-generation systems, as with the case of wave-power-generation plants, requires a reliable fault-ride-through capability. The effects of grid fault include uncontrolled turbogenerator acceleration, dangerous rotor peak currents, and high reactive-power consumption so that the plant may contribute to the voltage dip. A simple solution is automatic disconnection from the grid, but this policy could lead to a massive power-network failure. This is why new Grid Codes oblige these systems to remain connected to the grid. In this paper, an oscillating-water-column-based wave-power-generation plant equipped with a doubly fed induction generator is modeled and controlled to overcome balanced grid faults. The improvement relies on the implementation of a control scheme that suitably coordinates the airflow control, the active crowbar, and the rotor- and grid-side converters to allow the plant to remain in service during grid fault, contributing to its attenuation by supplying reactive power to the network and complying with new Grid Code requirements. The simulated results show that it obtains a great reduction of the rotor currents, improving the transients and avoiding rotor acceleration. Similar results are obtained from the experimental implementation.