A Microcomputer-Based Intelligent Load Shedding Relay

According to statistical records, there will be a major system blackout about every ten years. Some of them were because of improper operating of load shedding relays [1]. In order to have a more reliable system, utility engineers should adjust their load shedding relay setting points continually to satisfy the system condition. Unfortunately, they have neither intelligent relays nor convenient means to change the relay settings. As a result, most utilities use a set of frequency settings many years without updating it. This paper describes the design of a microcomputer-based intelligent under/over-frequency relay, that can adjust the setting points and time delays dynamically. This will give a power system a better opportunity to survive an emergency operating condition.