Reactive power control of DFIG-based wind turbine during voltage sag

Improving the Fault Ride Through capability (FRT) of Doubly Fed Induction Generators (DFIG) in wind power applications is a very important challenge for wind power industry. The mathematical models of such generators allow to analyze their response under generic conditions. However, their mathematical complexity does not contribute to simplify the analysis of the system under transient conditions, and hence do not help to find straight-forward solutions to enhance their FRT. This paper discusses an important point that is still absent in the Brazilian grid code. This point is the reactive power injection by the wind turbine during a voltage sag, in order to realize the voltage regulation at the point of common coupling (PCC). The advantages of such requirement to the system will be widely discussed in this work. Furthermore, the simulations and experimental results will also be shown in order to demonstrate the proposed ideas.