Fault Detection Based on the Discrete Wavelet Transform For the Converter of a Wind Power Generator System Operating Under Disturbances In the Grid

In this work, an open-circuit fault detection scheme for the converter of a wind power generation system is proposed and evaluated, which is robust to false detections under grid disturbance conditions such as sags and swells. The wind energy system is composed of a doubly-fed induction generator (DFIG) that supplies energy to the electrical grid through a power electronics converter based on the neutral point-clamped topology in a back-to-back configuration (NPC-BTB). The converter operates with a field-oriented-control (FOC) scheme, whereas the fault detection method is based on the processing of the current signals flowing through the converter at the rotor and stator sides of the generator using the discrete wavelet transform (DWT) with the Haar and Daubechies4 wavelet types. The fault detection scheme is evaluated verifying that false detections do not arise, analyzing cases where magnitude variations in the grid voltage of 15%, 30% and 50% occur, with respect to the nominal operating condition.