This paper presents a step towards the design of robust non-fragile power system stabilizers (PSSs) for
single-machine infinite-bus systems. To ensure resiliency of a robust PSS, the proposed approach presents
a characterization of all stabilizers that can guarantee robust stability (RS) over wide range of operating
conditions. A three-term controller (x1 + x2s)/(1 + x3s) is considered to accomplish the design.
Necessary and sufficient stability constraints for existing of such controller at certain operating point
are derived via Routh–Hurwitz criterion. Continuous variation in the operating point is tackled by an
interval plant model where RS problem is reduced to simultaneous stabilization of finite number of
plants according to Kharitonov theorem. Controller triplets that can robustly stabilize vertex plants are
characterized in a similar manner. The most resilient controller is computed at the center of maximum-
area inscribed rectangle. Simulation results confirm robustness and resiliency of the proposed
stabilizer.