Comparison among series compensators for transient stability enhancement of doubly fed induction generator based variable speed wind turbines

This study investigates the effects of series compensators, such as the dynamic voltage restorer (DVR), series dynamic braking resistor, thyristor switched series capacitor, and the high temperature superconducting fault current limiter (SFCL), in enhancing the transient stability of a doubly fed induction machine based variable speed wind generator system. The tested system consists of a 9 MW doubly fed induction generator based wind farm connected to an infinite bus through two step-up transformers and a double run transmission lines. A three-phase-to-ground (3LG) fault and a single-line-to-ground fault (1LG) were applied to one of the lines to demonstrate the transient stability enhancement ability of the series devices. A performance comparison among the four series compensators is made based on responses of active/reactive power, terminal voltage, rotor speed, dc link voltage, and current variations. Simulations were carried out in the MATLAB/Simulink environment. Simulation results show that all series devices can improve the transient stability, however, the SFCL is the most efficient in terms of active power, rotor speed stability and fault current suppression, and the DVR seems to have a better performance than the SFCL in terms of voltage and reactive power