A UPFC Supplementary Control Method for Suppressing LFO of Resonance Mechanism

Low frequency oscillations (LFO) of resonance mechanism are great threats to modern power system. Unified power flow controller (UPFC) can suppress LFO with appropriate control scheme. This paper proposed a supplementary controller on serial side of UPFC to suppress LFO of resonance mechanism. The method is a synthesized control of certain oscillation mode. The change of the oscillation mode can be achieved by controlling synchronous torque coefficient and damping coefficient. With the supplementary controller, the amplitude of LFO of resonance mechanism can be significantly decreased. To verify the validity of the proposed method, a single-machine infinite-bus system (SMIB) is used for simulations. The result shows a good effect of the proposed controller.