Impacts of Relays Coordination and Alternate Supply Availability on Radial Sub-Transmission Networks Reliability Assessment

Protection systems play a major role in the performance of electric power systems. There are a number of techniques such as redundancy within the relay system or local and remote backup methods to improve protection system reliability to remove faults as fast as possible, coordination of protective relays is very important. Also availability to neighboring systems affects significantly on repair time after occurring an event. An approach is presented in this paper to incorporate relay coordination and alternative supply availability on radial sub-transmission system reliability. For this purpose, a computer program has been developed. As a case study, a practical 63 KV sub-transmission network of Mazandaran Regional Electric Company (MREC) has been selected and studied. At the end, sensitivity analysis has been conducted to illustrate the impacts of alternate supply availability and relay success variation on expected energy not supplied index