Determination of Required Grid-Forming Capacity in 100% Inverter-Based Power Systems Based on Critical Inertia Calculation Under Korean Grid Code

This paper proposes a method for calculating the required capacity of the Grid-Forming inverter (GFM) according to the inertia requirement in a 100% Inverter-Based Resource (IBR) system. For this purpose, we also suggest a critical inertia calculation method based on Korean grid code. As the basis for the proposed method, using the System Frequency Response (SFR) model, we verified that reinforcing the inertia constant through the integration of GFM contributes to increasing the frequency nadir, and provided a mathematical interpretation of this effect. After that, for the simulation we assume a simulation environment, the 2023 Jeju island system operating at 100% IBR by providing the inertia from GFM, on the PSCAD/EMTDC and derived the required capacity of GFM by applying the proposed method in the constructed simulation system.