Load Frequency Control of an Interconnected Power System using Thyristor Controlled Phase Shifter (TCPS)

In an Interconnected power system, as a power demand varies randomly, both area frequency and tie-line power interchange also vary. Load frequency control (LFC) is of importance in electric power system operation to damp frequency and voltage oscillations originated from load variations or sudden changes in load demands. The objectives of load frequency control (LFC) is to minimize the transient deviations in these variables (area frequency and tie-line power interchange) and to ensure their steady state errors to be zeros. The control error signal in LFC is called area control error (ACE) which is a linear combination of net tie-line power error and frequency error. This paper presents the analysis of the load frequency control (LFC) of a realistic two area interconnected power system having diverse sources of power generation. A Thyristor Controlled Phase Shifter (TCPS) is used in series with AC tie line for improving the dynamic performance of the LFC system. The power system simulation is done using MATLAB Simulink and control problem is solved using MATLAB programming. An optimal integral controller with and without TCPS are obtained following a step load perturbation in either of the areas using Particle Swarm Optimization (PSO) algorithm with a strong ability to find the most optimistic results. Simulation results show that due to the presence of TCPS, the dynamic performance in terms of settling time and overshoot is greatly improved. The system with TCPS is capable of suppressing the area frequency and tie line power deviations more effectively under the occurrence of area load perturbations.