Fault Current Calculations for Interlinked Hybrid Microgrids

This paper presents a mathematical formulation for the fault current calculation in interlinked hybrid AC-DC microgrids. These hybrid microgrids are assumed interconnected through a multilevel converter. The calculations considered the layout of the converter and the switching schemes. The half-bridge Submodule (SM) configuration is considered for the multilevel converter configuration. The two fault scenarios, AC-side and DC-side faults, are studied to present a formula for the calculation of the fault current contribution from each subgrid during each fault scenario. An illustration hybrid system is simulated using MATLAB/SIMULINK during these fault scenarios. The results obtained from the simulation study are compared with the mathematical model presented in this paper. The agreement between the simulation results and mathematical model output proves the correctness of the proposed formulas to calculate the fault current and the contribution of each subgrid in both fault scenarios.