Power-flow control and transient-stability enhancement of a large-scale wind power generation system using a superconducting magnetic energy storage (SMES) unit

This paper proposes a novel scheme using a superconducting magnetic energy-storage (SMES) unit to simultaneously perform both power-flow control and transient stability improvement of a large-scale wind power generation system (WPGS) subject to severe wind fluctuations. A complete system model based on a synchronously rotating reference frame for the studied WPGS combined with the proposed SMES unit is derived and established. The output of the proposed SMES unit is properly controlled by adjusting both modulation index and phase angle of a bi-directional power converter to achieve the required simultaneous P-Q control. For demonstrating the effectiveness of the proposed SMES unit on performance of the studied WPGS, calculated operating conditions under different values of modulation index and phase angle as well as time-domain nonlinear-model transient simulations under disturbance conditions are both performed. It can be concluded from the simulation results that the proposed SMES unit can effectively control the desired power-flow conditions and render better damping characteristics to enhance transient stability of the studied WPGS under various wind fluctuations.