A gray-box hierarchical oscillatory instability source identification method of multiple-inverter-fed power systems

Weihua Zhou, Raymundo E. Torres-Olguin, Yanbo Wang, Zhe Chen

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24 Citations (Scopus)


This article presents a gray-box hierarchical instability source identification method of multiple-inverter-fed power systems, which enables stability analysis at system, component, and parameter levels sequentially. Impedance frequency responses of all components are first obtained using frequency scanning method. System impedance network model is then established by connecting these individual components based on system topology, which is further lumped into a loop impedance model (LIM). The vector fitting (VF) algorithm is then used to generate system state-space model from the impedance frequency responses of the LIM for eigenvalue-based stability analysis. If the system is assessed to be unstable, problematic components are further identified by performing impedance-based stability criterion at terminals of all components, where the numbers of right-half-plane poles are obtained by the VF algorithm. Finally, circuit and controller parameters of the identified problematic components are further identified using the VF algorithm, which are retuned to improve system stability. The proposed hierarchical instability source identification method is implemented in a multiple-paralleled grid-connected inverter system. Simulation results obtained in MATLAB/Simulink platform and real-time simulation verification results obtained in OPAL-RT platform are given to validate the correctness of the theoretical analysis results.

Original languageEnglish
Pages (from-to)3095-3113
Number of pages19
JournalIEEE Journal of Emerging and Selected Topics in Power Electronics
Issue number3
Publication statusPublished - Jun 2021
Externally publishedYes


  • Eigenvalues analysis
  • frequency scanning
  • grid-connected inverter
  • impedance-based stability criterion (IBSC)
  • instability
  • loop impedance model (LIM)
  • vector fitting (VF) algorithm

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