摘要

To detect the blade imbalance fault for direct-drive permanent magnet synchronous marine current turbine under the condition of wave and turbulence, an imbalance fault characteristics analysis method is proposed based on the frequency of the stator current. The instantaneous frequency of stator current is first estimated by total least squares-estimation of signal parameters via rotation invariant technique (TLS-ESPRIT) to solve the problem that the fault characteristic frequency is buried in the fundamental frequency and noise. Then, the generalized likelihood ratio test (GLRT) method is used to design the imbalanced fault detector in order to select the appropriate monitoring variable. At last, the data normalization method is proposed to solve the problem of various forms for a same imbalance fault caused by variable characteristic frequencies at different flow velocities. Theoretical analysis, simulation and experimental results verify the effectiveness of the proposed method. This method based on the stator current is easy to be realized, which has important practical significance for ensuring the safe and efficient operation of the marine current turbine system and reducing the maintenance cost.

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