Impact of Inverter-Interfaced Renewable Generation on Transient Stability at Varying Levels of Penetration

The transient dynamics of conventional power systems are dominated by synchronous generators. Because inverters serve as the primary interface between the power systems and low-inertia renewable energy resources, increasing penetration of such inverter-interfaced generation has a growing impact on the transient dynamics of power systems. In this paper, we attempt to quantify such an impact at different penetration levels. An elementary system, which includes one scalable inverter, one synchronous generator and one load, is studied under different parameter settings to assess the transient dynamics of the system. To quantify the transient stability, the post-fault Region of Attraction (ROA) of the system is estimated by the sample-based basin stability approach with parallel computing technology. Simulation results suggest that different inverter penetration levels, inertias of the generator, inverter-controller gains and phase-locked loop controller-gains have a clear impact of the ROA as well as the transient dynamics of the elementary systems. Increasing the penetration level of inverter-interfaced generations will decrease the volume of ROA of generators, which is also verified with a modified IEEE 9-bus system model.