Interval Approach Based Decentralized Robust PID-PSS Design for an Extended Multi-machine Power System.

The power system stabilizer (PSS) is vital to enhance the dynamic stability of the electrical grid. The conventional PSS, designed at a fixed operating point may fail to retain the system stability in real life due to varying system conditions. Hence, it is essential to develop a robust stabilizer that guarantees system stability and gives the best performance under wide-range scenarios. This research work presents a novel method to design a robust PID-PSS utilizing a decentralized approach. The extended multi-machine power system is divided into subsystems in this study. To depict broad operating conditions resulting from widespread system conditions, a transfer function with interval coefficients is developed for each subsystem. The necessary and sufficient constraints for robust stability are derived using a systematic way, and a performance index is devised to improve PSS performance. Global search and fmincon tool in MATLAB is employed to identify robust controller gains. The proposed method's efficacy is demonstrated using a two-area, 10-bus, four-machine system. The system is tested for short circuit faults that are both symmetrical and asymmetrical, as well as load disturbances. The proposed controller's robustness and superiority over the existing are demonstrated by nonlinear simulation results. [ABSTRACT FROM AUTHOR]