Microgrid fault clearance with linear programming algorithms

Electrical power grids are the backbone of all electricity distribution in the modern world. Faults in the microgrid may lead to blackouts or equipment damage. It stands to reason that we design our microgrids in such a way that a fault in a part of a network is isolated and does not propagate to the entire network causing a full blackout. Industry requirements specify that any fault leading from physical damage to the line, insulator flashovers, or even human error, be isolated within the affected section within instants of occurrence. This is because effects resulting from power line faults, such as overcurrents and voltage dips, are often seriously damaging to industry equipment which is expensive to replace. Hence the grid design should incorporate fault isolation and clearance procedures in order to obtain a reliable and adaptive protection system. Overcurrent relays have been found to be good fault isolators in microgrids. The relay must be protect the MG against faults in grid-connected and islanded modes and sense faults in the main grid in the former with high selectivity, sensitivity and reliability. The time coordination of overcurrent relay in microgrids may be achieved using different optimization algorithms. The algorithms considered in this paper are the Dual-Simplex method and the Karmarkar Algorithm. These algorithms contribute to the identification of the Time-Multiplier Settings of the overcurrent relays used in the microgrid.