Unified and Flexible Frequency-Domain Stability Assessment Framework for Power-Electronic-Based Power Systems

This letter proposes a frequency-domain stability analysis theory that provides the theoretical foundation for a unified and highly flexible framework for decentralized stability assessment of power-electronic-based power systems. By introducing frequency-dependent multipliers, the proposed method enables the seamless integration of existing decentralized stability conditions used in power electronics systems, including classical and weighted small gain, passivity, and frequency-split approaches. Moreover, it enables the flexible combination and deployment of novel, less-conservative stability criteria that cannot be obtained using any of the existing methods alone. Experimental validation on both stable and unstable systems demonstrates the framework's capability for accurate stability certification and the detection of localized instability risks.