Analysis of Substation Protection System Failures and Reliability

Protection system is one of the main parts of high voltage substations. This system includes many elements that should operate without any disruption. Failure of each element can lead to protection system failure and outage of substation. In this paper, the elements of protection system and their failure reasons are explained. In addition, according to failure rate of each cause that pertains to Iran sub-transmission substations, reliability analysis is carried out. Although due to design of protection system, protection system failure is not high, but it should be noted that because of role of different elements in protection system, more attention should be paid to reduce their failures.