A combined fault ride-through and power smoothing control method for full-converter wind turbines employing Supercapacitor Energy Storage System

•A combined fault ride-through and power smoothing control scheme for WTGs is proposed.•A Supercapacitor Energy Storage System is integrated in the power converter system.•An analytical expression for the sizing of the SCESS is calculated.•Optimal utilization of the SCESS by controlling the SoC is performed.

As the wind power installations are increasing in number, Wind Turbine Generators (WTG) are required to have Fault Ride-Through (FRT) capabilities. Lately developed grid operating codes demand the WTGs to stay connected during fault conditions, supporting the grid to recover faster back to its normal state. However, forcing a WTG to remain connected during a grid fault has consequences on the conventional protection devices, as they might become blind to over-currents and short circuits. This paper proposes a new control algorithm combined with a power management method, which fulfills the demand to keep the WTG connected to the grid during a fault, but disconnects the WTG when the fault insists. The energy generated while riding through a grid fault, is stored in a Supercapacitor Energy Storage System (SCESS). Furthermore, the SCESS is exploited for smoothing medium frequency wind power fluctuations, providing a high quality power profile. The simulation results which are performed on a 2 MW synchronous generator with external excitation, verify strongly the proposed power management method.