The influence of induction motor inertia constant on small-signal stability

The paper studies the influence of inertia constant (HD) of induction motor (IM) on small-signal stability in detail for the first time. Integral manifolds theory is introduced to reduce the order of the system state equations and formulate the oscillation frequency and the damping ratio. The theoretical analysis shows that HD mainly influences damping, the extent of which relates to the system structure and initial operating condition. The eigenvalue analysis of single-machine infinite bus (SMIB) system verifies the theoretical result, and the analysis of typical two-area power system shows the influence of HD on inter-area oscillation modes as the composition of the load and the location of the IM vary. In summary, dynamic IM load modeling is a necessity and the equivalent HD selected is significant in small-signal analysis.