Robust Diagnosis of Multiple Open-Circuit Faults in DFIG Wind Turbines in Both Sub- and Super-Synchronous Operating Modes

To keep up with the increasing demand for reliable and available wind turbines (WTs), condition monitoring and fault diagnosis are becoming increasingly important. In such systems, power switches of the power-electronic converter (PEC) are well known to be among the most reliability-critical components. In this context, this article presents a robust fault diagnosis approach for WTs based on doubly-fed induction generators (DFIGs) with the ability to handle multiple insulated-gate bipolar transistor (IGBT) open-circuit faults using only rotor current measurements and references, hence avoiding the need for extra sensors. The proposed method combines a chi-square
$\left(\chi^{2}\right)$
statistical test, normalized diagnostic variables, and adaptive thresholds to guarantee accurate diagnosis regardless of the operating conditions. The developed approach can detect and isolate all 21 combinations of single and double IGBT open-circuit faults in sub-synchronous and super-synchronous operating modes in less than one current fundamental period. It can also distinguish between IGBT and rotor current sensor faults. A 15-kW laboratory setup is used to demonstrate the proposed algorithm’s performance in both operating modes.