Small-signal stability analysis in power system dynamics examines whether a synchronous machine connected to an infinite bus returns to its original operating point after a small perturbation, by linearizing the nonlinear swing equation about the steady-state rotor angle and analyzing the resulting second-order linear characteristic equation. Stability is governed by the sign of the synchronizing (stiffness) coefficient — the slope of the power-angle curve at the operating point — and the damping coefficient: positive values of both yield damped oscillations that decay back to the equilibrium angle, while a negative synchronizing coefficient or negative damping produces growing oscillations and loss of synchronism, with the synchronizing coefficient reaching zero at the steady-state stability limit (maximum power transfer point).
Small-signal stability analysis in power system dynamics examines whether a synchronous machine connected to an infinite bus returns to its original operating point after a small perturbation, by lin…