A Laplace-Domain Circuit Model for Fault and Stability Analysis Considering Unbalanced Topology

• Published in: IEEE transactions on power systems Vol. 38; no. 2; pp. 1 - 3
• Main Authors: Miao, Zhixin, Fan, Lingling
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.03.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Circuit faults; Circuits; Domains; Dynamic circuit representation; Dynamic stability; Electromagnetic induction; ENGINEERING; fault analysis; Fault location; Induction motors; Integrated circuit interconnections; Mathematical models; Modelling; Power system dynamics; RLC circuits; Stability analysis; Steady-state; Subsystems; Topology; Unbalance
• ISSN: 0885-8950; 1558-0679
• DOI: 10.1109/TPWRS.2022.3230564

For systems subject to unbalanced faults, analytical model building for stability assessment is a challenging task. This letter presents a straightforward modeling approach. A generalized dynamic circuit representation is achieved by use of the Laplacian transform variable <inline-formula><tex-math notation="LaTeX">s</tex-math></inline-formula>. We translate the voltage and current relationship at the fault location into the relationship of three subsystems. The final circuit model is an interconnected sequence network with impedances in the Laplace domain. This circuit can be directly converted from a steady-state sequence network. This modeling procedure is illustrated by an example case of an induction motor served by a grid through a series compensated line. Electromagnetic transient simulation results demonstrate that sub-synchronous oscillations can be mitigated when a single-line to ground fault is applied at the motor terminal. Stability analysis results based on the dynamic circuit corroborate the simulation results. What's more, the derived circuit effortlessly reveals why unbalance can enhance stability.