Robust redesign of power system damping controllers

This paper presents a model-matching robustness design procedure based on H_∞-optimization theory for the robust redesign of nominal controllers. The approach directly uses a control law designed for the nominal operating condition and tunes the nominal control law to enhance the robustness with respect to the off-nominal operating conditions. The procedure is applied to the design of a power system stabilizer (PSS) for a single-machine infinite-bus system which has a range of possible operating conditions. The results show that the redesigned controller contains features similar to the nominal controller, but yet improves significantly the damping of the machine swing modes at the off-nominal conditions