Protection and control system use of non-conventional instrument transformers and process bus
2017-04-27 - NETA World article by Steven A. Kunsman, Nicholas Powers, and Bharadwaj Vasudevan, ABB - April 2017Digital substations are gaining traction, with real-world commercial installations now accepted among utilities. Main enablers for this technology are the non-conventional instrument transformers and standalone merging units using IEC 61850 process bus communication. IEC 61850 can improve the overall reliability and resiliency of the 21st century substation using digital communication. High-voltage measurement and control has recently improved to offer easily installed sensors with direct digital outputs offering excellent accuracy, stability, and faster frequency response. By going directly to digital, these state-of-the-art sensors preserve signal integrity and ease of connections through fiber communications. Unlike previous optical sensors that had some reliability concerns, the introduction of a new fiber optic current sensor (FOCS) design combines the inherent isolation of the optical current sensor with redundant systems to power, accurately process, and output signals capable of directly supporting substation automation. These modern optical sensors embedded in free-standing form using modern polymer insulators free of oil or SF6 gas — or integrated into other power equipment such as live or dead tank breakers and gas insulated substations — can simplify the merging unit architecture and deliver the full promise of IEC 61850 to utilities and their customers.
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This article was republished with permission from the 2017 Spring edition of the NETA (InterNational Electrical Testing Association) World Journal. Subscribe here.