JIC_V3_N2_RP1 Bethala Prasad Ch. Durga Prasad G. Pavan Kumar Journal on Instrumentation & Control Engineering 2321 – 1148 3 2 16 23 Load Frequency Control, Particle Swarm Optimization, PID Controller This paper presents the effects of load parameters and their variations on power system frequency and tie-line power. In this study the authors have selected two area thermal power system with Integral (I) and PSO-PID (Practice Swarn Optimization-Proportional-Integral Derivative) controllers. From the mathematical modelling of power system, frequency is a function of power system parameters and small changes in these parameters lead to small deviations in the system frequency and tie-line power. In case of extreme ends of parameters, even for small changes in load power there will be a chance of instability in overall power system. This paper deals with stable case for different parameter variations. Simulations are carried out in MATLAB/SIMULINK software. February - April 2015 Copyright © 2015 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=3536