Improvement of LVRT capability of variable speed wind turbine generators using SMES unit

The ability of variable speed wind turbines technology to optimally tracking the power from wind energy has become the main reason of their popularity compared with the fixed speed wind turbines. In the earlier stage of connecting wind turbines (WTs) to the existing electricity grids, WTs were allowed to be disconnected from the grid in case of grid faults which might lead to the damage of the turbines. However, recently, the transmission system operators (TSOs) require to maintaining the connection of WTs with the grid to support the grid during fault and to assure the continuity of power supply. This requirement has been compiled in new grid codes in several countries. In this paper, super conducting magnetic energy storage (SMES) unit is used with two different types of variable speed wind turbine generators to comply with Spain grid codes. Results show that the low-voltage-ride-through (LVRT) of Type-3 and Type-4 wind turbine generators are significantly improved when SMES unit is connected to the system.