[HN Gopher] Continental Europe successfully synced with Ukraine ...
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Continental Europe successfully synced with Ukraine and Moldova
power systems
Author : _Microft
Score : 174 points
Date : 2022-03-16 13:36 UTC (9 hours ago)
(HTM) web link (www.entsoe.eu)
(TXT) w3m dump (www.entsoe.eu)
| ISL wrote:
| _" and the adoption of risks mitigation measures."_
|
| i.e. We really need this yesterday. Stand back, let's see if it
| works.
| tpmx wrote:
| Background article from a week ago:
|
| https://www.wired.com/story/the-race-to-rescue-ukraines-powe...
|
| _The Race to Rescue Ukraine's Power Grid From Russia_
|
| _In late February, Ukraine began a long-planned 72-hour test to
| unhook its electricity grid from Russia's. Then the invasion
| started._
| liketochill wrote:
| Much better article. It says they have a 2000 MW transmission
| line between Ukraine and Europe.
| Hnrobert42 wrote:
| I know almost nothing about this, so this is a genuine
| question. Why do you say 2000 MW instead of 2 GW? Convention?
| Is 2 GW incorrect?
| GauntletWizard wrote:
| They're equivalent. Neither is more correct. Megawatts are
| a bit more understandable to the layperson, for the same
| reason that "a million dollars" is more understandable than
| "a billion dollars". A megawatt is about 1000 homes[1]. A
| gigawatt is a city.
|
| [1]https://www.eia.gov/tools/faqs/faq.php?id=97&t=3 A US
| Household uses slightly more than a kilowatt on average,
| though obviously peaks and troughs are well off that.
| mantas wrote:
| Looking forward to switching Latvia/Lithuania/Estonia from BRELL.
| aivisol wrote:
| This is long overdue. As well as unhooking from Russian gas.
| mantas wrote:
| Lithuania is already unhooked from Russian gas. LNG terminal
| in Lithuania can supply enough gas for all 3 Baltic states
| and there's a massive gas storage in Latvia. All 3 gas grids
| are well interconnected as well.
|
| Russian gas through pipe were cheaper than fully loading LNG
| terminal though.
| Hnrobert42 wrote:
| I am curious. What effects will that have?
| mantas wrote:
| So far Baltics' grids frequency is stabilised by Russian
| massive hydro plants. Technically Moscow can bring down
| Baltics grids if they want to and try to hard enough. Baltics
| could try to disconnect, but there's not enough stable power
| generation to keep frequency stable permanently. Big part of
| electricity is imported from Scandinavian hydros and they
| can't be utilised for stabilising the frequency.
|
| Another side effect - that means Kaliningrad would be
| unhooked from Russian mainland grid. They already have enough
| power generation on-site to keep the lights on, but I'm not
| sure if they have the means to stabilise frequency and enough
| redundancy if something bad happens. On top of that,
| political question comes up if it would become it's own tiny
| grid or become synchronised with continental europe grid too.
| Major Russian navy base attached to NATO-controlled grid may
| not sound cool for Russians :)
| kolinko wrote:
| Independence from Russia, ability to import/export
| electricity from/tu EU
| mantas wrote:
| There're import/export links to Sweden, Poland and Finland
| already. But they're connected through a converter rather
| than directly.
| pilsetnieks wrote:
| Scheduled for 2025 but I do hope it gets accelerated.
| mantas wrote:
| It was already delayed several times because of EU fears of
| Kaliningrad and Russia response. Hopefully now our
| politicians have enough arguments to make it happen.
|
| While at it, it may be good to stop the special permit for
| visa-free train from Russian mainland to Kaliningrad.
| earleybird wrote:
| It might be a tactical distraction that is needed at this
| point in time.
| mantas wrote:
| Military traffic is out of scope, so it'd be similar
| inconvenience as air space closure. But every tiny bit
| helps.
| spywaregorilla wrote:
| How secure is this? Is it actively supporting Kyiv? Eastern
| Ukraine?
| flavius29663 wrote:
| This seems like a huge engineering challenge, imagine
| synchronizing 40 million customers at 50 Hz
| WJW wrote:
| All those 40 million customers are already on a 50 Hz grid,
| it's just that the phase of the Ukrainian grid might be
| slightly different from the European grid. You can (with the
| correct know-how, training and access to generator controls!)
| fairly easily get one of the two to speed up or slow down by
| 0.1 Hz or something like that, wait until the grids match phase
| and then bring the frequencies back together. Now that they are
| the same frequency and phase, you can connect the networks just
| by flipping a switch and provided they were both in balance
| before the procedure no current will flow initially. Afterwards
| the two separate networks have effectively merged into one
| bigger network.
|
| It seems very complicated, but bringing generators and subgrids
| into sync is something that network operators do all day long.
| (Ship engineers too, since they can't rely on shore power for
| obvious reasons! You can have some very "interesting" outages
| if you forget to synchronize a newly started generator before
| connecting to the rest of the ship electricity system.)
| Knemejic wrote:
| Is this actually how it is done? I would assume that the
| complete ENTSO-E grid cannot be perfectly phase-synchronous
| anyway, simply due to the physical dimension of the grid and
| the speed of light.
|
| I would have guessed that frequency-synchronicity is
| sufficient for coupling two grids, and then you could use
| something like a phase shifting transformer to control the
| power flow?
| 323 wrote:
| Some country interconnections, in particular those to UK
| and Nordic countries, have the ability to connect even
| unmatched phases, by for example converting to and from DC
| (AC -> DC -> AC).
| lxgr wrote:
| Austria and the Czech Republic (Czechoslovakia at the
| time) used to have one of these too:
| https://en.wikipedia.org/wiki/GK_D%C3%BCrnrohr
| sebazzz wrote:
| That ability to connect unmatched phases is secondary to
| the primary function of those interconnects: over those
| distances it is more efficient to transmit the power in
| DC instead of AC. [0]
|
| [0]: https://en.wikipedia.org/wiki/High-
| voltage_direct_current#Ad...
| jamincan wrote:
| Sometimes connecting unsynchronized grids is the primary
| reason. The Outaouais HVDC Intertie is only about 35km
| long, but it allows the import and export of electricity
| between Ontario and Quebec.
| aerostable_slug wrote:
| This was how the Tres Amigas Superstation was supposed to
| work.
|
| Unfortunately, ERCOT decided they didn't want to be
| subject to the same regulations as the Eastern and
| Western interconnects, so the project collapsed.
| martin8412 wrote:
| Even more fun is that Denmark despite its' very tiny size
| is split in two when it comes to electricity. West
| Denmark is connected with East Denmark through HVDC.
| WJW wrote:
| As far as I'm aware this is how grid operations are done in
| the overwhelming majority of the world. You spin a
| generator up to speed, match phases and close the switch to
| connect it to the rest of the network. Due to how
| electricity works, if any connected generator is slightly
| out of phase with the rest that will generate currents
| causing it to pulled back into phase in a closed feedback
| loop. So while it is technically possible for a generator
| to be out of phase with the network, it can never be
| outside of phase for very long because literally all the
| other generators on the network are pulling it back into
| phase.
|
| If the grids are particularly far from each other and/or
| with differing frequencies, a DC high voltage line can be
| used instead but that is certainly not the most used
| method.
| ars wrote:
| I looked into this once, and they .... just don't worry
| about it.
|
| Each generator just matches whatever it sees. If you are
| trying to match two other generators (like in a triangle,
| and due to the speed of light it's impossible for all to be
| perfectly in sync), then it matches to an average of the
| two, and apparently that works.
| numpad0 wrote:
| Sounds like needs to be consistent within each subgraphs of
| grids and synchronous at connection points
| Armisael16 wrote:
| You only need to match phase at the connection point, so
| the phase of the grid in France doesn't really matter (as
| long as ENTSO-E isn't destroying itself before you do
| anything).
|
| This does get much trickier if you have multiple connection
| points and it is impossible to be synchronized at all of
| them because the in-grid distance between the two points is
| different on the two grids. Then you definitely do need
| fancier tricks.
| tremon wrote:
| True, but you need to have a very large unbalanced grid
| for that to occur: at the grid frequency (50 Hz), the
| corresponding wavelength is 6000 kilometer. So assuming
| that math is correct, you would need a path length
| difference of 3000km between two transformers to get full
| phase inversion between the paths.
|
| That's more than twice the max diameter of the entire
| European grid (Tunesia-Gibraltar-Turkey seems the longest
| path). So as long as there's transformers every few
| hundred kilometer, and multiple paths between most of the
| connection points, the overall phase synchronization
| should be adequate to not need those fancier tricks.
| [deleted]
| bckr wrote:
| This sounds beautiful, like producing music where your
| instruments are an entire continent's electrical grid.
| aerostable_slug wrote:
| Until you find your inner Hendrix and produce positive
| feedback on transmission lines.
| flavius29663 wrote:
| I knew they were also on 50Hz, I was just thinking that if
| they are on a different phase it could blow up or something.
| But now that you mention some details, it doesn't seem that
| big of a deal anymore, thanks! What happens if they were to
| connect them while on opposite phases?
| WJW wrote:
| Well, if the generators and/or motors of each grid are not
| in phase with each other then connecting the networks
| together will cause electricity to flow in such a way that
| the phase difference disappears. This will speed up the
| generators that are "behind" and slow down the ones that
| are "ahead" in terms of the weighted average phase. How big
| this braking or accelerating force is depends on how much
| electricity can flow and how "big" the networks are in
| terms of the total rotational inertia of all connected
| devices.
|
| I once was on a ship where the engineering dept unadvisedly
| connected a ~1.5 MW diesel generator to the network when it
| was out of phase and that shook the entire 6000 ton ship.
| We later calculated that the whole multi-ton rotor had
| rotated about 60 extra degrees in under a tenth of a second
| (in addition to already spinning at 50 Hz), so you can
| imagine the forces involved with that.
|
| In practice, there will be humongous circuit breakers that
| trip to protect the equipment.
| flavius29663 wrote:
| So the result is either really bad...or worse than that:
|
| - if the circuit breakers kick in, you might end up with
| a huge nationwide blackout. Pretty hard to recover from
| that - but at least you will recover directly in the new
| grid.
|
| - if they don't kick in, you get all the generators in
| Ukraine + Moldova struggling immensely, possibly breaking
| their encasings/bearings, a little less for Europe, since
| they would have more mass to resist this spike.
| liketochill wrote:
| You only need to adjust one generator to change the frequency,
| since Ukraine grid is in balance simply adding or removing
| additional power will alter the frequency.
|
| Controlling the voltage at the point of synchronization is
| probably done with tap changers on transformers but would be
| more complicated to ensure that power flows over the
| transmission line once it is connected are as desired.
| reincarnate0x14 wrote:
| It's not as huge as all that, most of Europe is already
| similarly synchronized and Ukrenergo was already running at 50
| Hz. The longer term concern is communication and coordination
| between the RTOs in Europe and Ukraine, as Ukraine must now
| respond to grid conditions and act to maintain as spelled out
| by complex and detailed operating procedures.
|
| Actually syncing up is more of a case of putting in some high
| resolution meters at the interconnect substation, or maybe some
| phase shifting transformers, and adjusting the Ukrainian side's
| frequency by a few micro-hertz an hour until the phase angles
| are close enough by setting frequency targets at the largest
| generators. Something similar happens all the time in wide area
| grids when generators are brought back on line.
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(page generated 2022-03-16 23:02 UTC)