Improvement of dynamic stability via coordinated design of PSS and UPFC in a two machine power system employing cuckoo search optimization technique

Abstract

Sustained electromechanical oscillations pose a major challenge to the stability of large power systems. To overcome this problem, nowadays power systems are equipped with power system stabilizers (PSS). They play a vital role in increasing damping and minimizing power system instabilities. However using only PSS to reduce oscillations during faulted conditions may not be sufficient enough to maintain stability. To handle large amount of power, power electronics based Flexible AC Transmission System (FACTS) devices are being extensively used. Synchronized use of PSS along with Unified Power Controller (UPFC) can result in further improvement in reliability, controllability and mitigation of power system oscillations thus further improving the system stability. In order to enhance the system stability to a greater extent, the PID controller parameters of the PSS are dynamically tuned through a unique and robust optimization technique called Cuckoo Search (CS). So this paper primarily aims to design a unique methodology to decide the most suitable PID controller specifications using the evolutionary Cuckoo Search algorithm technique for transient stability enhancement of a two machine power system, through coordinated design of PSS and UPFC. The transient stability of the system with the proposed CS technique based PID is compared and contrasted with the conventional PID under various faulted conditions. To justify and validate the enhancement achieved by the proposed technique, the two machine system is designed using the MATLAB/Simulink environment.