Thanks to its essential functionality and structure simplicity, proportional-integral-derivative (PID) controllers
are commonly used by industrial utilities. A robust PID-based power system stabilizer (PSS) is
proposed to properly function over a wide range of operating conditions. Uncertainties in plant parameters,
due to variation in generation and load patterns, are expressed in the form of a polytopic model.
The PID control problem is firstly reduced to a generalized static output feedback (SOF) synthesis. The
derivative action is designed and implemented as a high-pass filter based on a low-pass block to reduce
its sensitivity to sensor noise. The proposed design algorithm adopts a quadratic Lyapunov approach to
guarantee -decay rate for the entire polytope. A constrained structure of Lyapunov function and SOF
gain matrix is considered to enforce a decentralized scheme. Setting of controller parameters is carried
out via an iterative linear matrix inequality (ILMI). Simulation results, based on a benchmark model of
a two-area four-machine test system, are presented to compare the proposed design to a well-tuned
conventional PSS and to the standard IEEE-PSS4B stabilizer