Voltage Stability Margin (VSM) Excel Workbook – Modal & Continuation Methods

Voltage stability refers to the ability of a power system to maintain steady voltages at all buses following disturbances or gradual load increases. The VSM Excel Workbook bridges theoretical stability analysis with practical, spreadsheet-based engineering tools by embedding two complementary approaches: (1) Modal analysis computes eigenvalues of the reduced Jacobian matrix (e.g., dQ/dV or dP/dV submatrix) to identify critical modes and participation factors, revealing weak buses and dominant instability mechanisms; and (2) Continuation Power Flow (CPF) traces the P–V or Q–V nose curve numerically—using predictor-corrector schemes—to locate the maximum loading point (MLP), i.e., the SNB point where the Jacobian becomes singular. The workbook typically includes preconfigured IEEE test cases (e.g., 14-bus, 30-bus), interactive sliders for load/generation scaling, automated convergence handling, and visual outputs (eigenvalue plots, PV curves, sensitivity tables). Its Excel-based architecture supports accessibility for education, preliminary studies, and integration with legacy planning workflows—though it trades computational speed and scalability for transparency, modifiability, and low-barrier adoption. Validation against industry-grade tools (e.g., MATPOWER, PSAT, or PSS®E) ensures methodological fidelity while maintaining pedagogical clarity.