We propose a fast simulation model of wind generator with a frequency converter, such as a doubly-fed type. The aim of the model is to provide a model that can evaluate an impact of wind generator system (WG) on utility side in both transient and relatively long term normal operation. Through, some simulation software based on root mean square value, for example EUROSTAG, provides a unified method that can handle both short-term and long-term analysis. But it is difficult for RMS based model to handle with a behavior of WG with a frequency converter under system fault condition. So we have developed an instantaneous value based fast simulation model that can handle with both short-term and relatively longer-term analysis.