Analyzing Reliability Indices in Special Protection Schemes in Order to Increase Reliability and Capacity of Transmission Lines

Special protection schemes (SPS), known also as remedial action schemes, are those designed to detect one or more predetermined system conditions that have a high probability of causing unusual stress on the power system, and for which preplanned remedial action is considered necessary. The failure of these schemes to accurately detect the defined conditions, or their failure to carry out the required preplanned remedial action, can lead to very serious and costly power system disturbances. It is natural, therefore, that a concern for the reliability of these schemes has been expressed. On this basis, this paper analyzes the reliability of SPS and ensures its outcome with an acceptable probability.