Design of power system stabiliser for single-machine system using robust periodic output feedback controller

Power system stabilisers (PSS) are added to excitation systems to enhance the damping of low-frequency oscillations. The design of PSS for a single machine connected to an infinite bus using periodic output feedback is proposed. The nonlinear model of a machine is linearised at different operating points and 16 linear plant models are obtained. For each of these plants an output injection gain is obtained using the LQR technique. A robust periodic output feedback gain which realises these output gains is obtained using an LMI approach. This robust periodic output control is applied to a nonlinear plant model of the machine at different operating (equilibrium) points. This method does not require the complete set of states of the system for feedback and is easily implementable.