Planning and Coordination of Relays in Distribution System

Background/Objectives: A protective relay should proficiently distinguish between fault, normal and abnormal environments. The prime aim is to plan and coordinate the relays effectively during power system faults. Methods/Statistical Analysis: ETAP simulation tool is adopted for appropriately operating the backup relays, after giving acceptable time discernment for operating the primary region relays. The optimal identification of relay settings for both Main and Standby Protection is achieved using Fault Current Limiters (FCL) and Coordination Time Interval (CTI). The distribution set-up of Surana industries is considered for the analysis. Findings: The early detection of fault and automatic cutting off of defected portion ensures high degree of protection and instigates proper planning in any power system network. Normally the distribution system protection involves both principal relays and standby relays. The whole distribution system is divided into numerous intersecting zones to guarantee complete protection. Protective relays must function only for the precise protection for which they are intended, without functioning for any normal and short term tolerable abnormal happenings. Hence, during the failure of primary protection, the backup relays provide protection after some indicated time interval. The modern power systems use distributed network wherein which insertion and removal of DG units are common. This disturbs the relay coordination and initiates frequent operation of standby relays. Deciding the proper time interruption for the working of backup relays decides the protection quality in distribution link. Application/Improvements: The protection coordination of distribution set-up of Surana industries are formulated in ETAP after getting the power flow results using Newton-Raphson algorithm. Results show improvement over the existing methods.