Small signal stability analysis and optimal control of multi-area power system

An important issue associated with the stability of multi-area power systems is the low damping of electromechanical modes of oscillation. The local modes of oscillations are damped out using local PSS controllers, whereas separate controllers are required for the damping of inter-area oscillation as they require remote measurements as the feedback signal of the controller. This paper investigates the performance of a unified controller for the multi-area power system, designed based on the state space model approach. An optimal state feedback controller is designed using the LQR technique for the stabilisation of the system and in particular to improve the damping of the inter-area modes of oscillations. The performance of the controller during three-phase fault on the tie-line and change in reference input of governors and exciters are analysed. To study the adaptability of the controller, the system response at different operating points is also analysed.