Synchronverter-based frequency control technique applied in wind energy conversion systems based on the doubly-fed induction generator

The increasing penetration of wind energy conversion systems (WECSs) based on the doubly-fed induction generator (DFIG) has raised serious concerns about the stability of modern power systems. One important issue is the frequency control of interconnected networks, which may become more complex owing to the low inertia of wind turbines. In this context, this work presents a novel frequency control approach that associates the grid-side converter (GSC) with a synchronverter. To assess the performance of the proposed solution, a thorough comparison with other well-known frequency control techniques is presented, that is, pitch angle control and switching angle controller (SAC). Simulation tests of the IEEE 14-bus modified test system are carried out in PSCAD/EMTDC & REG; software to assess the behavior of a 165 MW wind farm (WF) when frequency variations occur. The results show that the classical control approaches can restore the system frequency within a time interval up to 63% shorter and a frequency dip lower than 13% when compared with WECSs that cannot provide frequency support. In turn, the synchronverter-based technique presents improved performance while attenuating a frequency dip by 45.7% and 56.9% when compared with the aforementioned strategies and WECSs without frequency support, respectively.