Reducing of power system low frequency oscillations by UPFC

With further complication of power system, the problem of low frequency oscillations in large electric network becomes more and more serious. Unified power flow controller (UPFC) is the most valuable and universal device in flexible AC power transmission system, which can improve system stability and inhibit low frequency oscillations under proper control. This paper intends to analyze the single-unit infinite system which includes UPFC in theory, expound how to inhibit low frequency oscillations by introducing the Lyapunov method. The fuzzy control strategy based on the revision factor is adopted. The corresponding controller is designed. Also the simulation for the single-unit systems is done, which concludes that UPFC can inhibit low frequency oscillations and improve system stability obviously.