Protection strategy for fault detection in inverter-dominated low voltage AC microgrid

This paper presents a protection strategy based on active power flow direction, current magnitude and voltage sags to determine the existence of low impedance faults in inverter-dominated low voltage AC microgrids. Different fault situations are considered, concerning each element of the microgrid (line section, load, node and energy sources). Simulation is done in MATLAB/Simulink software. Microgrid was modelled based on CIGRE benchmark for network integration of renewable and distributed energy resources, considering the low voltage european distribution network characteristics. Inverter-based distributed generation units were modelled considering a control scheme composed by natural reference frame control and RMS current limiter. The results obtained from simulations indicate that the proposed strategy is able to protect the microgrid in any topology configuration or mode of operation, for all type of low impedance faults.