Robust automatic generation control with saturated input using the ellipsoid method

This paper presents a new design for automatic generation control. The design incorporates the effect of control input saturation (constraint) as well as system's uncertainty due to changes in tie line power transfer. Violation of input saturation (corresponding to fully opened or fully closed control valve) may cause system instability. A new approach to this problem is proposed, which is based on the method of invariant ellipsoids. The result is in the form of nonlinear matrix inequality that contains only 1 nonconvex scalar. When the scalar is fixed, the powerful technique of linear matrix inequalities is then applied. The effectiveness of the proposed design is demonstrated on a multiarea load-frequency control model. Comparison with H_∞ technique is also given.