Masoud Radmehr - Young Researchers And Elite Club, Ali Abad Katoul Branch, Islamic Azad University, Ali Abad Katoul,Iran
Mehdi Mohammadjafari - Department of Electrical Engineering, Department Gorgan Branch, Islamic Azad University, Gorgan Branch, Iran
MahmoudReza Ghadisahebi - Department of Electrical Engineering, Department Gorgan Branch, Islamic Azad University, Gorgan Branch, Iran

A power system stabilizer is an ancillary device used for improving stability of otherwise poorly stable power system. It helps to restore the system back to the operating point after disturbances like load changes or faulty situations are withdrawn or smoother transition from one to another operating point. Originally, power system stabilizers are installed to add damping to local oscillatory modes, which were destabilized by high gain, fast acting exciters. Its property is to provide damping torque to reduce the electromechanical oscillations introduced in the system under disturbances.We analyze the model different types of small signal stability for a power system using linearized model and design a stabilizer for single machine infinite bus system. A comparison between the effect of LOC-pss and Cpss in terms of either power system responses or its eigenvalues due to different load condition is reported. Simulation results show the LOC- PSS is robust for such nonlinear dynamic system and achieves better performance than the CPSS in damping oscillations. the effective of the pss for different loads disturbance is illustrated with simulation cariied out in Matlab software.

Power System Stabilizer, Cpss, LOC-pss, SMIB, Heffron-Phillips, Robust Systems Control