Short Circuit Analysis and Coordination of Overcurrent Relays for a Realistic Substation Located in Upper Egypt

Protective relays and circuit breakers are major components of the large interconnected power system. Protection system is used to isolate only faulted parts from the power system network in shortest possible time leaving healthy parts in service causing a minimum disturbance to the power system. The protective system should be able to discriminate between normal or abnormal or fault conditions which called the discrimination. Protection coordination is the important task in protection system. Without good protection coordination, the protection system will lose its features i.e. selectivity, dependability, and sensitivity. The protection mis-coordination is the main problem in the power system. This paper presents short circuit analysis and relay coordination between overcurrent relays of a 132/33/11kV substation which located in Upper Egypt. The short circuit analysis, and relays coordination are performed by ETAP 12.6 simulation program.