Large Signal Stability Assessment of the Grid-Connected Converters based on its Inertia

The nonlinear characteristic of the grid-connected voltage source converters (VSCs) affects the stability assessment of power-electronic-based (PE-based) power system. Therefore, an appropriate model of the VSC that shows its nonlinear behavior is needed in order to evaluate the system stability, especially when the system is subjected to a large disturbance. In this paper, a nonlinear model of the grid-connected VSC based on its dynamic inertia is presented. In order to assess the large-signal stability of the system, the dynamic model of the equivalent synchronous machine (ESM) is monitored, then based on the inertia of the ESM, the stability margin of the system is determined. Results show that the stability boundaries can be determined based on the nonlinear model of the ESM inertia of the grid-connected VSC subjected to a large disturbance.