Application of discrete wavelet transform for identification of induction motor stator inter-turn short circuit

The harmonic elements of stator current in induction motors will change under the condition of stator inter-turn short circuit. According to this characteristic, in this paper, a novel technique based on discrete wavelet transform (DWT) is proposed for the identification of induction motor stator inter-turn short circuit. The power systems computer aided design (PSCAD) is employed to simulate the process of one-turn to six-turn stator inter-turn short circuit in a 3.7 kW (5 hp) induction motor by adjusting the impedance in series with one phase circuit. The Daubechies 45 (db45) wavelet transform is applied to one phase currents under normal and abnormal (voltage imbalance and varying load) conditions. The sixth level approximation coefficients obtained from the decomposition are used to structure the criterion for identifying stator inter-turn short circuit. Extensive simulation work has been conducted and results indicate that the scheme proposed in this paper has a high identification rate for induction motor stator inter-turn short circuit.