Dynamic output-feedback wide area damping control of HVDC transmission considering signal time-varying delay for stability enhancement of interconnected power systems

In this paper, an output-feedback-type wide area damping control (WADC) strategy is presented as a supplementary control of high-voltage direct current (HVDC) transmission to enhance thestability of large-scale interconnected power systems. This strategy can effectively suppress the varying-delay effects of wide area signal on the damping performance. A discrete-time system model that considers the varying-delay feature of wide area signal is established, then a dynamic output-feedback (DOF) type WADC is formulated by employing a new stabilization analysis method based on Lyapunov function. All the solutions of controller design problems are converted into the framework of linear matrix inequalities (LMIs). Compared to the conventional design method, the varying-delay of wide area signal is involved during each step of controller design, which is advantage to eliminate the effects of signal varying-delay on damping performance. Both the four-machine two-area test system and the sixteen-machine five-area interconnected system are used to validate the control concept and the designed controller.