Vibration Signature of Generator-Side Converter Faults for Wind Turbines

Vibration monitoring is one of the mainstream techniques in wind turbine condition monitoring systems, which has been used to diagnose mechanical faults of wind turbine subsystems. As the electromechanical coupling link in wind turbine, generator-side converter directly connects and controls the generator, while withstanding high failure risk. Fault diagnosis methods developed for generator-side converter faults basically rely only on electrical signals and have a certain false diagnosis rate. However, few studies focus on generator vibration signal abnormalities induced by electrical faults of generator-side converter, even though vibration monitoring systems are widely installed in wind turbines. In this paper, the frequency-domain vibration characteristics of generator-side converter faults are theoretically derived and experimentally verified. Through the envelope spectrum analysis of generator vibration signal, it is found that the characteristic frequency is the product of mechanical rotation frequency and pole pairs of generator. Then, a new fault diagnosis approach based on vibration signal is proposed by extracting phase feature corresponding to the characteristic frequency. Experimental results show that the diagnosis approach can effectively detect and locate open-circuit faults of generator-side converter. This work demonstrates that vibration signal is also an indicator for diagnosing electrical faults of electromechanical coupling multi-body mechanical systems, which is meaningful to develop reliable condition monitoring and fault diagnosis systems with multi-source information fusion for wind turbines.