Adaptive protection of transmission lines

Modern microprocessor based relays are designed to provide high speed protection under different power system conditions and configuration. Requirements for reduction in the duration of short circuit faults on transmission lines are based on significant system congestion and increased numbers of customers with loads sensitive to voltage variations. High-speed fault clearing for different faults on transmission lines can be achieved by advanced communications based protection schemes. However, they have the disadvantage that they require the availability of communications between the two ends of the line, which in many cases are not available.