APPLICA TION OF SLIDING MODE CONTROL TO DESIGN OF POWER SYSTEM STABILIZERS

Todays application of Power System Stabilizers (PSS) is common in most large power plants.The reason behind this is it was seen that low frequency oscillations in speed and power angle of generators due to a incidental disturbance can leads to loss of stability or at least limmits the dynamic capacity of power lines. Conventional power system stabilizers(CPSS) are designed based on a linearized model of a single machine connected to an infinite bus. CPSS commonly is a cascade of one or two phase lead controller and a high pass filter. Although the main application areas of sliding mode and variable structure control was in robotic and electric motor control, recently it is used in transient and dynamic stability studies of power system.in this paper, based on sliding mode control, a PSS is designed so that it has desirable performance in a wide range of power system conditions. To design a robust PSS, parameters of linearized model are obtained for some representative system conditions as full load, mid load lead load and loss of a line . Sliding mode control is applied to model with uncertain parameters. The result of simulation on nonlinear model of system are compared with those of CPSS. It is showen that performance of the presented SMPSS is superior over CPSS.