Assessing the reliability of adaptive power system protection schemes

Adaptive power system protection can be used to improve the performance of existing protection schemes under certain network conditions. However, their deployment in the field is impeded by their perceived inferior reliability compared to existing protection arrangements. Moreover, their validation can be problematic due to the perceived high likelihood of the occurrence of failure modes or incorrect setting selection with variable network conditions. Reliability (including risk assessment) is one of the decisive measures that can be used in the process of verifying adaptive protection scheme performance. This paper proposes a generic methodology for assessing the reliability of adaptive protection. The method involves the identification of initiating events and scenarios that lead to protection failures and quantification of the probability of the occurrence of each failure. A numerical example of the methodology for an adaptive distance protection scheme is provided.