Optimization of exciter and speed governor control parameters in stabilizing intersystem oscillations with voltage-dependent load characteristics

Tieline power oscillations can occur between interconnected utility systems, especially when the power transmission angles on the interconnections are relatively large. These oscillations can be controlled, however, by readjustment of exciter and speed-governor control parameters. A third parameter that has a significant effect on the damping of the oscillations is the load-voltage characteristic of the power system. Hence the load-voltage characteristic should also be taken into account in the parameter readjustment. The paper presents a systematic method of choosing these parameters by developing a state-space model of the excitation system with a speed stabilizer that interacts with the governor control system and the load-voltage characteristic. The Lyapunov equations for the linearized system are then solved to determine the optimum set of parameters. Finally, the effect of the choice of these parameters on the transient response of the dynamical system for small load changes is presented.