A New Fast Bus Tripping System Design of Protection Relay in an AC Power Network

In this paper, we develop a fast bus protection and automation strategy for adaptive overcurrent (OC) protection in an AC power network. The system includes the SEL751 and SEL751A relays communicating through IEC61850 generic object-oriented substation event (GOOSE) messages. The two relays can communicate with intelligent electronic devices (IEDs) at various locations. The system also consists of transformers, bus bars, and feeders with protection relays to detect OC faults based on time and current. The relay settings are tested based on 138/25kV substation values in the lab. Three points with different currents and fault times on both low-voltage and high-voltage sides are used in the test based on the selected time-overcurrent U3 inverse curve. The presented strategy can quickly clear both low and high-voltage faults of transformers and substations. The obtained results confirmed the effectiveness of the presented method in protecting AC networks.