In this book a dynamic models have been developed for the following: variable speed wind energy conversion systems and power electronic interfacing devices. These dynamic models are suitable for both detailed fast transient and large time scale performance evaluation studies. They can be used to expedite the research processes in the related alternative energy areas, such as system control, performance optimization studies and diagnosis. One of the original points is that this work is the use of a new the fault detection and isolation method (FDI). The proposed method avoids the exploration of all the combinations for its application to the diagnostic of this system operation. The causal paths are used to generate the analytical redundancy relations (ARR) at each computation step based on the constitutive and structural junction relations. This is shown through an algorithm for monitoring the system by sensors placements on the corresponding bond graph model.