A Logic-Based Technique for Backup Protective Relays

摘要

This article presents a logic-based technique for backup protection schemes. The technique is used to identify the faulty line and to estimate the proper delay time for backup relays involved in the fault clearing process. The technique is not affected by typical difficulties for traditional expert systems, such as complexity of the network, errors in impedance estimation or lack of some information. The network topology is stored in such a way to avoid the setting dilemma of backup relays and to deal flexibly with the running changes in the network topology. The proposed technique is examined successfully under different operating scenarios.