A microcomputer-based intelligent load shedding relay

The authors describe the design of a microcomputer-based intelligent under/over-frequency relay (the MAC-1) that can adjust the setting points and time delays dynamically. This gives a power system a better opportunity to survive an emergency operating condition. The decision making of this device is not only based on the previous setting but is also dependent on the current system situation. Compared to existing load-shedding relays, this device costs less, is easy to maintain, performs the self-diagnostic, and has high flexibility. Furthermore, this device records system data during normal and emergency conditions