Suboptimal Power System Stabilizers for Multi Machine Systems

Jawad Talaq


Supplementary control, Power system stabilizer, Power system dynamics, Optimal control


Excitation supplementary control is used in power systems to enhance the damping of low frequency oscillations due to the mechanical modes of the generators. Traditionally, frequency deviation is fed back to the exciter through phase lag-lead compensators to form the supplementary control. This supplementary control is known as power system stabilizer (PSS). An optimal power system stabilizer (OPSS) based on linear quadratic regulator design and utilizing the conventional phase lag-lead structure of PSS may be implemented to achieve optimal performance. However, due to the difficulty of feeding back all states to the stabilizers, a suboptimal power system stabilizer (SOPSS) can be designed by neglecting the coupling gains between machines and feeding back only the speed deviation and the PSS states. In this paper, a SOPSS is proposed and compared with the conventional phase lag-lead power system stabilizer. Simulation results of a multi-machine power system example are presented.

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