Frequency Stability Assessment of the Jeju Island HVDC-Linked Power System Considering the Grid-Forming Capacity under High Renewable Penetration

This paper presents an EMT-based frequency stability assessment of a power system with high renewable energy penetration, focusing on the role of grid-forming (GFM) inverters during large disturbances. PSCAD/EMTDC simulations are performed to investigate system frequency responses under three operating scenarios, including load step changes, HVDC line disconnection with different GFM composition ratios, and HVDC disconnection under high renewable penetration. Frequency nadir and rate of change of frequency (RoCoF) are adopted as key performance indices to quantify dynamic stability. The EMT model is established by reflecting projected Jeju Island system conditions based on the 11th Basic Plan for Electricity