Explicit Design of Optimal Fuzzy PSS: D-Decomposition Approach

Abstract

This paper presents a Power System Stabilizer (PSS) design to improve rotor angle stability in a Single Machine Infinite Bus (SMIB) system using a D-Decomposition approach. It shows that a Fuzzy Logic PSS (FLPSS) functions effectively as a standard PD controller during small signal disturbances. Thus, selecting scaling factors for the FLPSS is akin to designing a robust PD controller, merging the linearity of PD control with the flexibility of a Fuzzy Inference System (FIS). The D- Decomposition approach identifies an optimal point for σ and ζ stabilization, revealing that the σ Hurwitz stability boundary can be expressed as a line segment at maximum σ. The intersection with the ζ boundary yields both maximum σ and optimal ζ, providing the desired parameters for the PD-based PSS while considering system nonlinearities. The proposed design is compared with those optimized through meta-heuristic algorithms to emphasize its advantages. A robustness test based on the Hermite-Biehler theorem confirms the system’s stability under parametric uncertainties.