Doubly-fed induction generators (DFIGs) are the most widely used types in wind turbine (WT) systems due to their mechanical reliability and control flexibility. Electrical faults however remain a major concern in DFIGS in which accurate fault detection (FD) and fault-tolerant control (FTC) of their electrical parts play a crucial role to increase their reliability and availability and those of the entire wind farms. More particularly, voltage dips (VDs) effects on both the stator and the rotor of a DFIG make it vulnerable to frequent failures which are undesired in practice. This article therefore introduces a model-based design for efficient and robust fault detection, identification, and estimation in addition to a compensation control scheme for VDs in DFIGs. An adaptive proportional integral observer (APIO) is designed for detection and compensation of VDs with a robust FTC that allows fault-ride-through capability and maintains the stability and smooth operation in DFIG-based wind power generation. The proposed observer and the fault tolerant controller of the nonlinear DFIG are designed through Lyapunov theory to ensure sufficient stability conditions described by a system of linear matrix inequalities (LMIs). These designs are then analysed across various tests for their VDs detection, estimation, and compensation capabilities.

Keywords: Fault tolerant control, Voltage dips, Fault detection, Doubly-fed induction generator (DFIG), Lyapunov theory, Linear matrix inequalities (LMIs) conditions