The 3MIB benchmark system proposed in  is comprised of six buses and three generators. The 3-machine-infinite bus (3MIB) benchmark system is used for assessing the effectiveness of power system stabilizers to simultaneously contribute to the damping of electromechanical modes of different nature: from the intra-plant to the inter-area modes.
Download the Three Machines Infinite Bus Benchmark System case.
 F. J. De Marco, N. Martins and J. C. R. Ferraz, “An automatic method for power system stabilizers phase compensation design,” IEEE Trans. on Power Systems, vol. 28, pp. 997 – 1007, May. 2013.