SELECTION THE BEST CONTROL CHANNEL FOR SSSC STABILIZER TO DAMP INTER-AREA OSCILLATION CONSIDERING NON-LINEARITY EFFECTS

Modal interaction noticeably affects the dynamic behavior of a stressed power system with heavy loading. In this paper, Modal Series (MS) as a method to analyze modal interactions is extended for a power system installed with a static synchronous series compensator (SSSC) stabilizer. The ø- based and m-based stabilizers as two stabilizers in different control channels are presented for a SSSC. The parameters of the stabilizers are calculated by a quadratic mathematical programming method. In this procedure, the gain and the phase of a stabilizer are calculated simultaneously. A particular measure of stabilizer gain is considered as an objective function. The effects of SSSC based stabilizers on damping inter-area oscillations for a small disturbance are studied and compared. Modal interactions between an inter-area mode and control modes related to SSSC stabilizers are studied by a proposed index based on MS method in a 4-machine stressed power system. Oscillatory instability caused by modal interactions is investigated and compared in the system for both SSSC stabilizers.