Assessing the frequency support provided by DFIG wind turbines according to current standards

Nowadays, wind turbines commonly installed in new plants include a power converter. This allows these generators to operate in a variable speed range with the aim of maximizing the primary source exploitation. On the other hand, the presence of a converter implies a partial decoupling from the grid. Several studies have been carried out to enhance the ability of wind turbines in supporting frequency stability in the case of network events, and some grid codes recently include these regulating functions as required specifications. This work presents a novel control system applied to a Doubly Fed Induction Generator to make it compliant with present Italian standards. In order to characterize the role of wind turbines in supporting network frequency, several simulations have been carried out in the DIgSILENT PowerFactory environment. Main advantages and disadvantages are identified and discussed, depending on both the wind turbine operating conditions and the characteristics of the required stabilizing contribution.