USA isn't in much of a better position.
Large scale transformer blowouts are a nightmare scenario due to how long they take to replace / repair.
Large scale transformer blowouts are a nightmare scenario due to how long they take to replace / repair.
For fast transformer replacements we rely on two paths, either system spares (identical units, sometimes refurbished or like in kind replacements) and more recently mobile resiliency transformers. Resiliency transformers are trucked in on semis and can operate at 69, 138, or 345KV in our case. (There's some lightweight reading on them here: https://www.tdworld.com/overhead-transmission/siemens-introd...)
Years back I remember ConEd was replacing two or three very large transformers down the street of a large venu I was working an event. Turns out we worked the same event the next year and amazing the same day ConEd again had the second transformer scheduled to moved into place. What an operation. Huge trailer from Bay Crane along with one of their giant hydraulic cranes. Was told the transformer weighed in at 240,000 pounds.
I know a few people in the ConEd trenches, one guy is a lineman who does all the >=69kV stuff and the other guy worked in substations and was in mott haven last I spoke to him (cushy job).
I'm always amazed how much new tech con ed has installed and how much old stuff is still kicking around. I live in south queens and we're all 4kV overhead fed from area subs in turn fed by 27kV. Some of those 4kV poles have westinghouse transformers from the 30/40's still in service, glass insulators, and leftover wooden pins from older insulators. Some are so old the primaries have fallen off and just hang between two adjacent poles, some the crossarms are half falling off. Amazing this grid doesn't go down more. Then the next pole is brand new, composite strain insulators, cutouts, reclosers, metering, etc. All modern hardware. And I know some areas they upgraded the 4kV overhead to 27kV. The secondaries are in even worse condition, ancient cloth insulation half weatherd/baked off. But it all still works.
I really love how there's this massive network of cabling and systems which orchestrate the flow of power from multiple synchronized generators so it can get to your humble wall socket and charge a phone or turn a light bulb on.
(I'm not an EE, so not sure how many variables one needs to contend with in grid-scale transformer design)
Older stations were actually designed around the transformers in some cases and the physical configuration of a 50+ year old failed unit is rarely like those produced more recently. We might have a unit on hand that is electrically equivalent but impossible to install without essentially rebuilding the entire station.
To give a rough overview of the range of transformers on our system, the first thing we care about is the voltage and MVA rating, then whether the bushings are open air or gas insulated, what the winding configuration of the primary and secondary are (delta-wye being most common), whether the unit it is replacing has a tertiary winding (sometimes at transmission voltage, other times distribution or for light and power to the station), and then maybe what accessories it comes with such as current transformers for protective relaying.
A perfect like in kind replacement could possibly be done entirely by construction using proper procedure of documenting their disconnects if there were no structural modifications required to move the units in/out. This is rarely the case however and so we need to check everything from phase clearance on making the high voltage connections to whether disconnecting a failed transformer will trip out another perfectly healthy one, possibly making the situation much worse.
All that being said, we make every attempt to triage the work required and get information to construction as soon as possible so that no time is wasted waiting for engineering. We can have a conceptual layout circulating within engineering in a few hours and out to the field by the next day. Field technicians can tag and disconnect terminals right away while we figure out how to wire up the new unit. Perhaps in a perfect situation you might get all this done in a few days with all hands on deck but that's more luck than aptitude.
Interesting. I had always wondered how utilities interact with local permitting. I had assumed they would work something out to have standardized permits for common work which they could leverage during incidents but that seems that's not the case.
One of the biggest issues is that traditional resources (coal, nuclear, gas) can run for long periods of time and in many places have a pretty reliable fuel supply. Renewables are great, but you could be generating lots of power one minute and then it's all gone the next hour. This causes a lot of stress on traditional resources which need to be ready to counteract this. Coal plants and gas plants were never designed for that either and it's causing issues.