Comparison between the improved sequence network model of wind turbines and the classical model based on sequence networks for short-circuit studies

Space vector theory is a widely used tool to model synchronous and asynchronous machines. In this paper the induction machine dynamic equations were written in terms of space vectors, employing the stationary reference frame. Also, a general short-circuit current expression was derived and decomposed into positive and negative sequence components. In order to validate and compare the model developed with a simplified model found in literature, short-circuit simulations with balanced and unbalanced sources were performed. The results shown that, for some cases, the mismatches between those approaches are relevant and cause some problems during design, coordination of protection and control stages of machine systems. Discrete Fourier Transform (DFT) and mean squared error (MSE) were used to accomplish this comparison. Finally, a different approach for modeling sequence voltages was proposed and compared with the two methodologies aforementioned.