A systematic robust decentralised design procedure based on the H-infi
nity-optimisation technique for tuning multiple FACTS devices is prese
nted. The design procedure uses a model-matching robustness formulatio
n and requires the design of a parameter to achieve decentralised cont
rol. The approach is used to design damping controllers for an SVC and
a TCSC to enhance the damping of the interarea modes in a 3-area 6-ma
chine system, The feedback signals for the controllers are synthesised
from the local voltage and current measurements.