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

摘要

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 (AVR) where the power system stabilizer (PSS) 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 (DGR) for switching off the detrimental signals. Relevant frequency domain analysis of the closed loop transfer function of a typical power system is provided which reflects the effect of tie-line disturbances on power angle oscillations. This leads to a restructuring of the transfer blocks in the system and the design of a DGR block that allows the decoupling of the negative damping signals. Additional insight into the effect of negative damping signals and their subsequent decoupling is provided through the examination of loop and transfer block signals.