Transmission line protection systems with aided communication channels—Part II: Comparative performance analysis

Abstract Following the Part I paper, a comparative performance analysis is presented, considering four different transmission line protection schemes, equipped with aided communication channels. In the Part I paper, the performance analysis methodology was presented, which is based on a probabilistic approach to protection system successful operation. The system performance takes in account equipment reliability factors such as failure rate and time to repair, and is assessed by the availability index. In the present paper, new performance indicators are introduced, which are applicable to transmission line protection system design, as well as to describe its probabilistic operation in other power system studies. Four different transmission line protection schemes with aided communication channels, operating in today's transmission networks, are compared. The results obtained for the performance indicators allow quantifying the benefits of the different design options. In particular, the effect of relay and communication channel redundancy, as well as communication channel sharing, is highlighted. Furthermore, results show that the newly defined performance indicators can be used in a cost/benefit analysis, as well as to assess maintenance strategies and communication reliability requirements.