Overcurrent Coordination in Systems with Distributed Generation

The presence of distributed generation in electrical distribution systems greatly modifies their traditional structure. Overcurrent coordination studies in distribution systems using circuit breakers, reclosers, and fuses have been conducted using two methodologies that were based on constant magnitudes and directions of overcurrents, from the main source toward the end users. These techniques cannot be of general application when distributed generation is involved. The proposed methodology allows overcurrent coordination studies for non-constant, two-source currents. The application results are provided in both graphical and numerical forms. Several examples are given where the potentiality of the new methodology can be assessed, explaining the process for circuit breaker/fuse, fuse/fuse, and recloser/fuse coordination. The method can be applied to any overcurrent coordination study including non-constant, cyclic loads.