The objective of this research is to evaluate the performance of a Power System Stabilizers (PSS), designed using a formulation based on Linear Matrix Inequalities (LMIs), in an Electric Power Distribution System (EPDS) with distributed synchronous generators operating under unbalanced three-phase. Under these conditions, the steady-state operation of the EPDS is not an equilibrium point, which introduces a new condition not covered by typical PSS design techniques. To overcome this problem, an EPDS modeling technique developed on a previous work by the authors research group was used. For the PSS design, a technique called V-K iteration was employed and the maximization of the minimum damping was set as the controller design objective. Furthermore, three LMI solvers were used (and compared) to assess design feasibility. A total of 880 operating points (for which the open loop minimum damping was smaller than 3%) were considered for the design. The results show that the proposed formulation is feasible and good controller performances can be achieved by the different PSSs designed using each of the tested LMI solvers.