Stability is a primordial concern of power systems. From the generator point of view, it means that the machine must be able to attain an equilibrium state (possibly the pre-fault state) once the system is back to normal operation. For Synchronous Generators, the Equal Area Criterion (EAC) can be used to determine the maximum fault clearing time also known as critical clearing time. Such criterion is not valid for Induction Generators. In fact, only a few works aimed for a stability criterion for Doubly-Fed Induction Generators (DFIG). Since the EAC uses the power-angle profile of the synchronous machine, the work done here proposes the use of the power-slip profile of the DFIG. Using the power-slip profile of a DFIG, an analytic method for critical fault clearing time for a DFIG is developed. The analytic values calculated using the criterion are compared with values obtained through simulations showing accurate results. Hence, the method can be used as an indicator for transient stability for DFIG.

International audienceThis paper presents the nonlinear control of a Fully-Fed Synchronous Machine based Variable Speed Pumped Storage Plant (FFSM PSP). First, a model is developed and the control objective is established followed by the control design. The control algorithm is designed using Feedback Linearization robustified by a Second Order Sliding Mode Control (SOSMC). Using both techniques allows a fast response of the system while relaxing the conditions on the Sliding Mode Control and avoiding the known chattering problem. The control is compared with the industrial standard PI controller from the dynamic response point of view and also during short-circuits

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