This document presents a robust control H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> based in Linear Matrix Inequalities applied to a power multimachine interconnected system, which is expressed such as Differential and Algebraic linear model. The strategy permits to damp oscillations generated by changes in operation point of each subsystem and input perturbations in mechanic power. The strategy only uses minimal available information in output static feedback form. The feedback variables are local and remote for each machine. The control law is probed in a matlab/simulink simulated three machines benchmark. The simulations and the results are showed at the end of paper.