Condition monitoring and winding fault detection of inductors in LCL filter integrated with active front end rectifier

This paper presents an online Condition Monitoring (CM) methodology for inductors in LCL filter integrated with Active Front End Rectifier (AFER). The proposed methodology monitors the winding flux of each phase of grid side and converter side inductors and compares with the winding flux under healthy condition to detect and identify the winding fault. The developed technique uses the Fast Fourier Transform (FFT) to extract the magnitude of the fundamental component of the winding flux. Hence, low bandwidth magnetic flux sensors integrated with a simple FFT algorithm can be used to detect and localize the winding fault. The effectiveness of the fault detection methodology has been analyzed and studied using the developed mathematical and FEM model. The proposed methodology has been tested on a laboratory prototype of 1.4 kVAr inductor at different input voltages and short circuit resistances. Both simulation and experimental results are found to validate the proposed fault detection methodology.