Damping of oscillations using TCPS with BF technique in a three-area thermal system

This paper presents Automatic Generation Control (AGC) of two and three area thermal systems. Each area of the systems is equipped with single reheat turbine and has a Generation Rate Constraint (GRC) of 3% per minute. System dynamics has been obtained by considering 1% step load perturbation (SLP) in area 1. Performances of several classical controllers such as Integral (I), Proportional-Integral (PI), Integral-Derivative (ID), Proportional-Integral-Derivative (PID) and Integral-Double Derivative (IDD) has been evaluated and compared in the two area system. Bacteria Foraging (BF) technique has been used for optimization of controller gains. Investigations reveal that IDD controller provides better dynamic than the others. Thyristor-controlled Phase Shifter (TCPS) in tie-line has been used for damping the oscillations in the frequency and tie power deviations. TCPS is applied in both systems with IDD controller in the secondary loop. An appropriate tie-line for use of TCPS in series has been selected. Investigations reveal that using TCPS the oscillations and peak deviations in the responses can be reduced. Simultaneous optimization of Governor Speed Regulation parameter (R_i) for primary control loop and gains IDD controller (K_Ii, K_Di) for the three unequal area system with IDD controller using BF technique provides higher values of R_i, thereby leading to economic and convenient realization of Governors. Sensitivity analysis has been performed to see the robustness of K_Ii, K_Di and R_i obtained at nominal condition on the three area system with TCPS with wide change in loading conditions, Inertia constant(H) and magnitude and location of SLP and established that they are robust.