Wide-area stability control for damping interarea oscillations of interconnected power systems

Abstract

In order to damp interarea power oscillations of interconnected power systems, the authors propose a two-loop framework of a wide-area stability control system, wherein the inner loop generates real-time damping control actions using wide-area feedback signals, while the external loop adjusts the controllers' parameters in a near-real-time way to accommodate the variation of operation conditions. A systematic approach is presented to design the control system, which includes an efficient model-reduction method based on the disturbance-injection technique and an improved Prony algorithm; the concept and calculation method of comprehensive observability and controllability to properly locate observers (PMUs) and controllers; co-ordinated and optimised tuning of multiple control gains; and a least-squares-based polynomial prediction algorithm to handle the communication delays. The proposed wide-area control system has been tested with a practical 262-machine, 1726-node interconnected power system. The modal analyses and the nonlinear simulation results have shown its effectiveness and advantages over traditional local PSSs in damping interarea oscillations and improving across-area transfer capabilities.