Open-circuit faults diagnosis and Fault-Tolerant Control scheme based on Sliding-Mode Observer for DFIG back-to-back converters: Wind turbine applications

One of the most common types of wind turbines is the Doubly-Fed Induction Generator with a back-to-back converter. The Insulated Gate Bipolar Transistor switch's open-circuit fault rate compared to the fault total rate in the wind turbine is noteworthy. The converter Insulated Gate Bipolar Transistor open-circuit causes a drawback in output current and as a result, the production performance of the turbine is reduced. In this article, a new method is presented for multiple Insulated Gate Bipolar Transistor open-circuit faults for open -circuit faults diagnosis. After the fault occurs, to maintain the performance of the turbine, fault compensation is performed based on the new Fault-Tolerant Control scheme. The proposed method is inexpensive, and for fault detection and location determining no need for additional sensors and hardware. This method uses residual output based on the Sliding Mode Observer with SAT function to detect faulty phase and overcome chattering Doubly-Fed Induction Generator converter. To residual evaluate and reduce the false alarm rate against changes in operating points and transient currents, the adaptive threshold is used. For efficient control of active or reactive power and dc-link voltage, a six-leg converter control based on Simplified Space Pulse Width Modulation is replaced by a five-leg converter based on Space Vector Modulation. Several experimental results using hardware in the loop Doubly-Fed Induction Generator test setup with a back-to-back converter are presented. It is shown the fault diagnostic algorithm is effective and robust against false alarms for both rotor and stator-side converters. The experimental result presents that the Fault Tolerant Control scheme can make power switch fault easily managed by the hardware reconfiguration and new control strategy adjusting.