When a microgrid transitions from grid-connected to islanded mode, adjustments to relay settings are essential to maintain protection coordination because the fault current levels and system impedance change significantly. In grid-connected mode, the utility grid provides a strong source of fault current, typically several times the rated current of the equipment. Relays are set to coordinate with the utility's protection scheme, ensuring that the relay closest to the fault trips first, isolating the faulted section while minimizing the impact on the rest of the system. However, in islanded mode, the fault current is primarily supplied by the distributed generation (DG) units within the microgrid, such as solar PV inverters, wind turbines,....
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