Residual‐Free Excitation Inrush Suppression for Three‐Phase Interconnected Circuit Breakers

As the cornerstone equipment of power systems, transformers may generate magnetizing inrush currents during no‐load energization, potentially causing equipment damage and system instability, which constitutes a critical technical challenge requiring urgent resolution. This paper proposes a novel synchronized phase‐selective closing strategy applicable to three‐phase gang‐operated circuit breakers that eliminates the need for precise residual flux measurement. Through comprehensive analysis of the inrush current generation mechanism and core residual flux variation patterns, we reveal that the three‐phase residual fluxes form a slowly rotating vector triangle that stabilizes when the post‐opening voltage decays to a critical threshold. Building on this discovery, the proposed method employs the residual flux vector at the opening instant as a reference and initiates breaker closing at the identical phase angle after integer power‐frequency cycles, ensuring perfect alignment between the anticipated flux and residual flux vector to prevent deep core saturation. Theoretical analysis, simulation studies, and experimental verification collectively demonstrate that compared with conventional flux‐difference function methods, the proposed strategy achieves superior inrush current suppression while significantly reducing dependence on residual flux measurement accuracy. This breakthrough substantially enhances both engineering applicability and operational reliability in practical power system applications. © 2026 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.