Deploying digital substations: Experience with a digital substation pilot in North America

Though IEC 61850 GOOSE has been in use for a while for various applications such as controls, interlocking, blocking etc. with substations across the world running successfully in a multi-vendor environment but IEC 61850-9-2 Sampled values and switched Ethernet process bus have yet to gain popularity. The use of NCITs (Non-Conventional Instrument transformers) have been limited to some niche application so far, such as measuring GICs, Open Phase detection, measuring very low magnitude AC, measuring DC etc. Introduction of IEC 61850 process bus and availability of NCITs have led to the way to real word deployment of Digital Substations. There have been several papers published and studies done on the design benefits and various tangible and non-tangible savings attained in digital substations as compared to Conventional Substations. This has interested utilities across the world to start deploying digital substations as pilot projects to realize the real-time benefits, understand the difficulties or ease to deploy such systems and have practical experience while comparing digital substation to a conventional system. This paper discusses PECOs perspective in deploying one of the first digital substation pilot projects in North America. The pilot project is installed on a 230kV line connected to the ring bus managed by PECO, Philadelphia. The main aim of the project is to evaluate and learn the state of the art digital substation technology and compare the various aspects to a conventional substation. The project involves primary optical sensors, merging Units, Protection IEDs supporting 9-2LE, IEEE 1588 Clocks, Substation Servers and Substation hardened Ethernet switches.