An Imbalance Fault Detection Method for MCTs Using Voltage Signal

In recent years, more and more attention has been paid to marine current turbines (MCTs). Attachments on blades will influence the system operation by causing imbalance and it is essential to monitor its working state, repair or replace the faulty blade (s) to reduce its damages. Imbalance fault detection of MCTs using electric signals has many superiorities compared with traditional vibration-based method. However, there are some shortcomings in using decomposition method to weaken the influence of waves and turbulence. This paper proposes a method to detect the imbalance fault of MCTs using voltage signal. In this proposed method, the instantaneous voltage frequency and average voltage frequency is calculated through Hilbert transform (HT). Meanwhile, the imbalance fault frequency is extracted by using the cubic spline interpolation. Finally, the wavelet transform (WT) method is used to detect whether there is a blade imbalance fault. The effectiveness of this method is verified by theoretical analysis, simulation results and experimental results.