Digital substations are gaining traction, with real world commercial installations being accepted among utilities. Main enablers for this technology are the non-conventional instrument transformers and standalone merging units, utilizing IEC 61850 process bus communication. IEC 61850 offers to improve the overall reliability and resiliency of the 21st century substation using digital communication. High voltage measurement and control has recently been improved to offer easily installed sensors with direct digital outputs that have 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 by using 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 be used to simplify the merging unit architecture and deliver the full promise of 61850 to utilities and their customers.
The introduction of stand-alone merging units provides an equivalent approach to digitizing the secondary signals available in the switchyard. This approach also, simplifies the mode of communication between the equipment in the switchyard to the relays in the control panel. In coherence to the IEC61850 standard, the merging units easily virtualizes any CT or PT signal available today from a conventional sensor. By implementing these merging units in the so called process bus, the complete potential of adhering to the IEC61850 standard can be envisioned.
This session discusses basic application variants, results and field experiences involving the NCIT, combined with the flexibility and modularity of the stand-alone merging units for process bus IO system. As well, the paper covers field installations of the GIS sensor technology and the availability of 61850-9-2 implementation.
An overview will be provided to show the digital substation’s key benefits highlighting safety, reliability, functional consolidation, and cost drivers leading to customer savings. Utilities are facing an increased demand on substation information and the digital substation opens the door for real time data exchange. The Digital Substation solution’s key technologies (relays, advanced substation automation and modern instrument transformers) are the advantages where IEC 61850/Ethernet are positioned as technology enablers and not obstacles.