Decoupling negative damping signals in a power system through dynamic gain reduction measures

Low-frequency oscillations occurring in a power system can be accentuated in generators through a feedback loop which connects the output of the system to the summing junction of the automatic voltage regulator where the power system stabilizer is also connected. A method of decoupling these oscillations without compromising the benevolent effects of other control loops in that system is presented. A notch filter, located in the forward path of the negative damping signal, provides the necessary dynamic gain reduction for switching off the detrimental signals. The authors provide a frequency-domain analysis which explicitly evaluates the gain characteristics of the transfer function that reflects the effect of tie-line disturbances on power angle oscillations. The justification for adopting the proposed scheme is given. Simulation results are presented