An Event Triggered Sliding Mode Control-Based Fault Ride-Through Scheme to Improve the Transient Stability of Wind Energy Systems

This paper proposes an event-triggered sliding mode control (ETSMC)-based fault ride-through (FRT) scheme for doubly fed inductor generator (DFIG)-based wind energy systems. The design aims at mitigating dynamic instabilities resulting from grid faults by properly regulating the dc-link voltage with support from a supplemental energy storage (super-capacitor). The high-density power support from the super-capacitor is efficiently facilitated by the dual active bridge converter (DABC) because of its high voltage conversion ratio and very low core loss. The event-triggered SMC approach allows updating the control input only when certain stability conditions are violated, thus reducing the computational burden and mitigating the chattering effect typically presents in the standard SMC. The ETSMC is augmented by a disturbance observer to achieve robustness against mismatched disturbances and parameter fluctuations. The design is validated using a DFIG-based wind energy system connected to a feeder of a microgrid network. The obtained results confirm the performance and capability of the proposed scheme to provide the FRT support by effectively regulating the dc-link voltage and reducing converter loading. Additionally, the ETSMC approach with the event triggered features can ensure the low usage of communication channels and improved harmonic distortion due to low chattering.