Fiber to the Yard 1

[davidbeach]

Anybody done a merging unit substation? Either an IEC 61850 based design or a proprietary scheme like SEL's TiDL? I see a possibility to save a bunch of wiring installation and checkout time with something that seems more plug and play than conventional wiring, but also see a huge paradigm change to get there. I'd really like to know of real life examples of it being done, particularly examples that could be visited. For various reasons I'm inclined more toward TiDL than conventional 61850, but any good examples, regardless of protocol, would be welcome. If you've done at least two, are you/would you do more? What would you do differently vs. what would you keep doing? Thanks.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[stevenal]

David,

Our main stumbling block is reproducing the look and feel of existing installations. We have large ammeters at the top of the panels, avoiding the need to examine or scroll relay displays. It would seem we'd still need to pull copper just for this purpose. When a large display is available for TiDL, I expect we'll look at it.

 

[davidbeach]

No analog meters in our case; only considering it for transmission and that metering all just goes to SCADA anyway. Might have a bit of a hard sell on the lockouts, but I think I have a solution there. We're looking at a significant amount of construction over the next many years and I'm looking at this as a possible way of increasing our throughput. First one or two probably won't be any quicker, but we need something. I'm sort of thinking it might be along the lines of how we were very comfortable with the SEL-3xx family a decade plus ago but I drove some SEL-4xx projects on things that the 3xx family had trouble with. Lots of growing pains along the way, but it didn't take too long before the Techs were ruing work where we had SEL-321s. Nobody could now imagine going back. Gut feel says something like this might be similar. But actual early adopters with success stories could make the sell easier.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[bacon4life]

About 10 years ago I installed several nonconventional instrument transformers. All but one of them has failed in some way have and been replaced with conventional instrument transformers at great inconvenience. Hopefully other folks are having better luck moving away from traditional wiring.

Seems like an entity would need to build several similar substation within a few year timeframe to achieve economies of scale with the new training and technical skills required for merging unit based stations. It seems like IEC 61850 keeps evolving fairly rapidly, so substation built only a few years apart might end up with different technology.

 

[cranky108]

I had looked at merging units, but as our testing engineer pointed out, where would you place the test set? And where would the test switches be?
The tech's then made it clear they preferred being in the building then out in the yard to do the testing.

 

[davidbeach]

Testing is definitely a concern. A thought is to use separate merging units during the testing, and then reconnecting to the field merging units. In-service testing would confirm that that relays are again talking to the relay. That's analogous to disconnecting from the field instrument transformers and breakers for testing and then reconnecting. Today that's done with lots of test switches. With the merging units it could be just a few fiber connectors instead.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[scottf]

bacon4life...I believe your experience with non-conventional instrument transformers is the norm for most. "Optical" CTs have been a round now for many decades and, in my opinion, the reliability hasn't really improved much over that time period. I think the same applies to NCITs on the voltage side too.

I'm admittedly biased (but for good reason) and I believe if one wants to go with a 61850 (or similar) solution, using conventional ITs and converting their analog output to digital is still the best and most reliable option.