Study of Synchronous Machine Excitation and Governor Systems in the Power System Stability Using PID and Fuzzy Logic Controller

Abstract

Changes in real power affect mainly system frequency, while reactive power is less sensitive to changes in frequency and is mainly dependent on changes in voltage magnitude. Therefore, in a system when the load changes, the voltage and frequency of the system also changes. In this study, automatic generation control system was used, to control the real and reactive power of a power system in order to keep the system in the steady state. MATLAB-SIMULINK simulation software using fuzzy logic controller FLC and proportional integral derivative PID control was used to control the voltage and frequency changes due to some specific load variation for normal and heavy loading conditions to obtain the input output data of the synchronous machine. The mathematical modeling of the system is the first step of controls system analysis and design. Work presented in this thesis has used transfer function (TF) method to develop mathematical model of synchronous generator with exciting system for stability analysis, state space model with linear differential equations for system description is used. In second step we develop the actual mathematical and Simulink models to examine the stability of power system. From the study it was observed that FLC controller model gave shorter settling time and smaller overshoot after specific load variation (perturbation) as compared with the conventional PID controller. Although, most of the earlier works on AGC studied the load frequency controller and automatic voltage regulator loops apart. In this paper however, combined LFC and AVR loops was studied and dynamic response of combined LFC and AVR was also analyzed. Detailed analysis of the results was discussed.