A new fault ride-through control for DFIG-based wind energy systems

Abstract

This paper deals with the design and analysis of a fault ride-through control (FRTC) scheme for a DFIG-based wind turbine. A new Fuzzy Second Order Integral Terminal Sliding Mode Control (FSOITSMC) is designed for the rotor and grid-side converters. The design is further augmented by a series grid side converter (SGSC) in order to avoid DFIG’s disconnection from the grid during faulty conditions. The proposed control paradigm was implemented on a DFIG-based wind turbine. Its performance was assessed using DFIG’s realistic modes of operation such as normal, sub- and super-synchronous modes. Both symmetrical and unsymmetrical faults were considered to further evaluate the performance of the proposed approach. Simulation results proved the ability of the proposed FRTC scheme in effectively controlling DFIG-based wind turbines under various operating conditions. Despite subjecting the DFIG to various modes of operations and extreme faulty conditions, the over currents of the rotor and stator did not exceed 10%, which is a very good performance compared to existing approaches.The proposed approach was able to maintain the DFIG’s currents and voltages within acceptable ranges, hence preventing damages to the converters during various faulty conditions. Endowing the DFIG with superior ride through capabilities and ensuring its continuous connectivity to the grid even under non-ideal grid voltage conditions are among the positive features of the proposed approach.