Transient Response Analysis in IBR-Dominated Power Systems Based on Short Circuit Ratio

Inverter-Based resources (IBRs) play a major role in transition to renewable energy, which poses new threats to the power grid’s stability and dependability. As conventional synchronous generators are replaced by IBR causes decrease in the inertia of the grid. As the penetration level rises, the grid’s strength decreases, making it more vulnerable to disturbances. This paper presents a dynamic performance evaluation of a grid-following inverter(GFLI) under varying grid strengths, characterized by different Short Circuit Ratios (SCRs). The inverter is designed with a constant DC voltage source, an L-filter interface, and a cascaded control structure that includes inner current control loops and outer power control (PQ) executed in the synchronous dq reference frame. The transient behavior and current tracking performance of the inverter are examined by applying a step change in active power reference. The system responses are observed by time-domain simulations. The analysis highlights the influence of grid strength on the Efficiency of the control strategy, especially in weak grid conditions. Results demonstrate that the proposed control strategy maintains stable operation and accurate power delivery under strong to moderately weak grid conditions, while performance degrades significantly under weak grid scenarios.