The goods & bads of digital substations
Here at EEP, we have already covered multiple aspects of digital substations, ranging from design, upgradations, and whatnot. We may continue writing till eternity and still be left playing catchups with the latest addition to advancements in power systems design and operation. Nevertheless, in this article, our focus shall be on the possible contingencies and turn of events when the coveted connectivity of modern digital substations goes haywire.
Or, how to cope if the internet or ethernet is down in digital substations? Normally, a fully automated digital substation in a power grid is connected to a remote server through the internet over an optical channel.
Remote communication or the internet we know of today is associated with many functionalities in a digital substation, and its disruption is never a desirable situation for substation engineers.
- Demarcation of digital substations
- Emergence of ethernet and internet in digital substations
- What if no ethernet?
- Internet in digital substations
- Conclusion and frequent queries
1. Demarcation of digital substations
Substation automation, time synchronization, data acquisition, monitoring, and alarming are some of the primary functions either facilitated or enhanced by digital substations, having already existed in different forms and phases. The availability of a modern communication backbone has been instrumental in transforming the way substations are designed and operated.
That is what demarks the operational territory of a digital substation – IEC 68150 compliant communication and interoperability between the process and station level equipment, all channeled through ethernet or optical link.
Breach or abnormalities in this territory could trigger a catastrophe in substations.
Figure 1 – A concept diagram of a digital substation
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2. Emergence of ethernet and internet in digital substations
The introduction of microprocessor-based relays in the early 1970s in substations laid the foundation for the current sophisticated version of Substation Automation Systems, aided by first-generation digital serial communication options- RS 232 and RS 485.
Although very capable, they had their limitation in data transfer rate and coverage, which eventually pushed for the inception of ethernet, a more advanced serial data communication standard.
RS 485 was a clear upgrade over RS 232 due to its fast data transmission rate and differential mode of operation that allows multidrop connections suitable for automation systems.
Still, the substation automation systems were never at full potential until the introduction of ethernet as the ultimate serial communication option for digital substations. Their fast data transfer rate, connection flexibility via cable or fiber, and support for redundant connection topologies made them stand out from the rest.
As the substations now depend on ethernet connectivity more than ever, IEC 61850, an international standard defining communication protocols for intelligent devices at electrical substations, has readily succeeded the MODBUS, DNP3, and IEC 60870-5-103 communication protocols.