Multiple open-circuit fault diagnosis for back-to-back converter of PMSG wind generation system based on instantaneous amplitude estimation

To increase the reliability and availability of wind turbines, a new diagnosis method was proposed for multiple open-circuit faults in the back-to-back converters of turbines using permanent magnet synchronous generators (PMSGs). This method is the first to use the instantaneous amplitude (IA) as the principal quantity for formulating diagnostic variables that can distinguish different states of any switch accurately without being affected by speed variations. The method also uses the weighted sliding Hilbert transform (WSHT) to estimate the IA to remove the influence of end effects and carry the information of multiple open-circuit faults. To locate faulty switches, a localization method using signal samples adaptive processing was employed to eliminate the influence of speed changes. Finally, combining these diagnostic variables with identification thresholds makes it possible to detect and locate 21 open-circuit fault combinations for the PMSG-side and grid-side converters. Compared to the conventional fault diagnosis methods, simulation and experimental results showed that the proposed method more efficiently and reliably detects and locates multiple open-circuit faults of PMSG wind power converters.