Power Swings Damping Improvement with STATCOM and SMES Based on the Direct Lyapunov Method

In this paper a comprehensive approach is presented to improve power swings damping based on direct Lyapunov method. The approach combines superconducting magnetic energy storage (SMES) system with static synchronous compensator (STATCOM). Considering the energy absorption/injection ability of SMES, in transient states the combination exchanges both active and reactive powers with power system. Since direct Lyapunov method relies on time derivative of both active and reactive powers, it can offer an effective control strategy for the integrated STATCOM-SMES system to decrease power swings damping time. Line current is proposed as synchronous reference frame for d-q transformation which satisfies the direct Lyapunov method application as optimized approach and also provides decentralized control strategy. Steady state control strategy with respect to proposed reference frame and also SMES existence is given.  PSCAD/EMTDC simulation results for a typical multi-area system are presented.Direct Lyapunov method, Power Swings, UPFC, SMES.