Protection Coordination for Distribution Systems in Presence of Distributed Generators

摘要

Coordination among protective devices in distribution systems is affected by inserting distributed generators. This is attributed to the changes in power flow in addition to the changes of magnitudes and directions of fault currents, which cause mis-coordination between protection devices. This article presents a new protection coordination to overcome the impacts of distributed generator units and to avoid the mis-coordination problem. The proposed protection coordination depends on activating the directional protection feature, which is available in most modem microprocessor-based reclosers. This will be accompanied by updating relays and recloser settings to achieve the correct coordination without extra costs or equipment in the distribution system when equipped with an autorecloser. A real 11 -kV feeder, simulated by the ETAP package (ETAP, Irvine, California, USA), is used to prove the effectiveness of the proposed protection coordination. The results ensure the possibility of achieving proper coordination between protective devices after inserting distributed generator units if suitable settings of these devices are realized.