Spider Monkey Optimization Technique For Damping Inter Area Oscillations Through Unified Design of PSS and TCSC

Abstract

Nowadays electromechanical oscillations of lower frequencies (LFO) have become a quite common phenomenon in modern power systems, posing a major threat to stability and security of the systems. For mitigation of these oscillations to improve system stability, Power System Stabilizers (PSS) are provided in power systems. However, in cases of certain faults and increased loading in a transmission line, equipping power systems with only PSS might not be enough. For better controllability as well as improved stability, Flexible AC Transmission System (FACTS) technologies are predominantly used in power systems. With unified use of FACTS devices along with PSS, there is improvement not only in just control of the power flow and response but also further enhancement in power system stability by damping out oscillations. Thyristor Controlled Series Capacitor (TCSC) is a modern versatile FACTS device extensively used in power systems for its effectiveness in rapid regulation of voltage, maintenance of balance in power flow and hence leading to greater stability limits as compared to other FACTS devices. However the linear control methods might not be effective in design of coordinated parameters. Hence taking nonlinearities in power system into consideration, a robust and unique evolutionary optimization technique termed as ‘Spider Monkey Algorithm’ is used for dynamic tuning of PID specifications of PSS for improvement of system stability to a much greater extent. The SMO based PID controller is designed and compared with conventional PID for justification and validation of the enhancement achieved, in terms of transient stability performance using MATLAB/SIMULINK environment by subjecting it to non linear loading conditions. The results demonstrate greater transient performance and immense potential of dynamically tuned SMO technique based PSS-PID of the two machine system as compared to the conventional PSS based PID controller.