The effect of electromechanical wave controllers on inter-area modes

Observations from synchronized phasor measurements (PMUs) have confirmed the fact that real power disturbance propagate over the power network with a speed well less than that of light. By treating an electric power network as a continuum system, a nonlinear partial differential equation in the form of a wave equation has been derived to describe the propagation of the disturbance, which further shows that electromechanical disturbances, also called electromechanical waves, propagate in the power network with finite speeds. As a result, electromechanical wave controllers (EWCs) based on the wave theory have been developed to damp electromechanical disturbances. The most typical one is impedance matching controller. While doing a good job in damping electromechanical waves, the effect of these EWCs on the small signal stability of the system especially on the low frequency inter-area oscillations is unknown. This paper studies the effect of such EWCs on the inter-area oscillations of the system based on the 127-bus equivalent of the Western Electricity coordinating Council (WECC) system.