• • The proposed constant-parameter VBR model achieves a 55.6% reduction in computational time compared to the MATLAB/Simulink SPS model under identical simulation accuracy, directly enabling larger simulation step sizes and faster grid stability assessments for system operators.
• • Two-norm voltage errors remain below 0.33% at node 5 and 0.3% at node 9, while current errors are 0.51% and 0.41%, respectively, under single-phase grounding short-circuit faults, confirming the model's precision in fault transient scenarios critical for protection relay coordination.
• • The hybrid explicit-implicit Euler discretization eliminates algebraic loops without iterative calculations, preserving numerical stability at large step sizes where traditional implicit methods fail or require excessive iterations, reducing simulation runtime for IEEE 14-bus system tests.
• • Piecewise linearization of the magnetic saturation curve enables accurate representation of saturation effects that, if ignored, cause core electrical quantity errors exceeding 10%, thereby preventing overestimation of equivalent reactances and misjudgment of voltage stability margins in grids with high renewable penetration.