Design a Wide-ara PSS for damping inter-area low-frequency oscillation

Based on the inter-area oscillation characteristics in interconnected power system, the machines participating in oscillation can be equivalent to a two-machine system according to their respective inertia center. This paper first deduces electromagnetic torque coefficient for the equivalent two-machine system, which lays the foundations of electromagnetic torque analysis of inter-area oscillation mode. On this basis a Wide-area PSS with two-channel feedback structure is presented, and the extended phase compensation method is adopts to coordinate mapping and conversion by a transfer function between wide-area and local feedback state variables, at last the mechanism of Wide-area PSS to damp inter-area oscillation is analyzed systematically. Simulation results show that it can not only damp inter-area mode effectively, but also improve small signal stability limit. Compared with other stabilizers, the proposed two-channel Wide-area PSS is helpful to make better the damping characteristic of the system.