The design of delay-dependent wide-area PSS for interconnected power system with prescribed degree of stability σ

The usage of remote signals obtained from a wide-area measurement system (WAMS) introduces time delays to a wide-area PSS, which would degrade system damping and even cause instability. This paper presents a novel method for designing a delay-dependent wide-area PSS to improve the angular stability of multi-machine interconnected power system with delay margin and prescribed degree of stability as additional performance indexes. The proposed method includes three parts: a residues approach for selecting the most effective signals to damp inter-area oscillation and designing phase-compensation parameters, a delay-dependent stability criterion to guarantee the asymptotical stability and an optimization algorithm to calculate the delay margin which constructs correlation between signal transmission delay, inter-area oscillation damping performance and prescribed degree of stability by transformation operation in complex plane. Case study is undertaken based on a four-machine two-area power system to demonstrate the design principle and verify the feasibility of the proposed method.