Development of a substation digital protection and control system using fiber-optic local area network

A substation protection and control system was developed and has been under trial use at a 50 kV substation. The system's digital protection and control equipment are located close to the outdoor power apparatus, and they are linked by an optical local area network (LAN). An IEEE 802.4 token-passing bus was used as the protocol of the LAN system. Optical star couplers were used for the physical layer. A specially designed synchronous sampling mechanism is also applied to the token bus to make the system more effective. Three manufacturers fabricated terminal equipment, which was linked by the optical LAN. Their interoperability was verified.<
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