Fault‐tolerant predictive power control of a DFIG for wind energy applications

Abstract

This study presents a new fault-tolerant predictive power control strategy for doubly-fed induction generators (DFIGs) used in wind energy applications, with the rotor fed by a three-level neutral point clamped converter. The proposed control strategy is able to maintain the system in operation with a good performance after the occurrence of either open-circuit (OC) or short-circuit faults in the insulated-gate bipolar transistors (IGBTs) of the rotor-side converter (RSC), thus reducing the downtime and maintenance costs of wind turbines. The fault-tolerant strategy takes advantage of the discrete nature and flexibility of finite control set model predictive control strategies and restricts the possible switching states of the power converter according to the type of fault and its location. A diagnosis method for IGBT OC faults in the RSC, based on voltage errors, is also proposed for the considered system. This method uses the estimated rotor voltages from the DFIG model, thus avoiding the use of any extra sensors. Accurate and fast detection of OC faults in both interior and exterior IGBTs is achieved throughout the entire DFIG operational range. The effectiveness of the fault diagnosis method and fault-tolerant control strategy is validated with several experimental results.