Wide-Area Measurements-Based Two-Level Control Design Considering Signal Transmission Delay

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> In this paper the design of power system stabilizers for small-signal stability using phasor measurements is considered. An approach based on optimal control with structural constraints is proposed to design a two-level control structure. Time delays are included in the design. The method is combined with order reduction to ensure faster convergence of the design algorithm and to facilitate the choice of the weighting matrices for damping interarea modes. The control scheme is discussed and modal analysis and time-domain simulations of two Brazilian equivalent systems are performed to assess the control performance. The robustness to loss of communication links, topological changes, and variations of time delay is evaluated. </para>