Inter-turn Stator Fault Detection in Doubly Fed Induction Generators Based Wind Turbines Using Generator Current Amplitude Demodulation by Discrete Cosine Transform

Wind energy conversion systems, taking into account economical and environmental factors are gradually gaining interests as a suitable source of renewable energy and play an important role in the renewable energy sources. Failure detection as always been a demanding task in electrical machines community: it has became more challenging in wind energy conversion systems because sustainability and viability of wind farms are highly dependent on the reduction of the operational and maintenance costs. In order to make wind turbines as competitive as the classical electric power stations it is important to reduce the operational and maintenance costs that for this purpose, we should continuously monitor the condition of these systems. This paper provides a method for electrical fault detection in doubly fed induction generator based wind turbines. The proposed method uses the current amplitude demodulation of stator current signal. The demodulated signal is transformed by Discrete Cosine Transform and in the next step of signal processing we compute a special parameter as the fault detector. Finally by comparing the value of this especial parameter with the supposed threshold value, we can detect the fault in moment.