Power system stabiliser for multimachine power system using robust decentralised periodic output feedback

Power system stabilisers (PSSs) are added to excitation systems to enhance the damping during low-frequency oscillations. The design of decentralised robust PSS for four machines with ten buses using periodic output feedback is proposed. The nonlinear model of a multimachine power system is linearised at different operating points and 16 linear state-space models are obtained. For each of these models an output injection gain is obtained using LQR technique. A decentralised robust periodic output feedback gain which realises these output injection gains is obtained using the linear matrix inequality approach. This method does not require states of the system for feedback and is easily implemented. The robust decentralised periodic output control is applied to the nonlinear model of a multimachine system at different operating (equilibrium) points and gives encouraging results for the design of power system stabilisers.