12 ms·

Black Start

289 points by anthonyb 13y ago

sp332 13y ago
I was wondering why nuclear plants require so much power to start up, when really you can't "shut off" uranium's power-generation ability. I guess it would have to do with powering up all the safety and management systems around the generator?
- aiiane 13y ago
  Uranium (or other radioactive materials) don't directly generate much electricity - they mostly generate heat. Most nuclear power plants generate electricity by having that heat turn water into steam, which is then used to power steam turbines that actually drive the generator coils. Of course, in order to do this, you have to be able to pump water into the reactor to be turned into steam, and that pumping requires power. So yes, while you definitely need power for the safety/management equipment, the major bootstrap issue is almost certainly all of the power necessary for the pumps.
  - mseebach 13y ago
    The article touches on this: Generating plants using steam turbines require station service power of up to 10% of their capacity for boiler feedwater pumps, boiler forced-draft combustion air blowers, and for fuel preparation.
- mschaef 13y ago
  Modern nuclear plants have two cascaded cooling loops and run at about 33% efficiency. This means that a 1000MW plant has 3000MW of thermal energy to manage at full load and 2000MW of energy to dissipate safely. The systems to do this take a great deal of power to run, so can't be bootstrapped off of batteries. Also interesting is that power prices will occasionally go negative in cases where there's a 'surplus' of generation. What's happening in these cases is that generation owners are making the judgement that its more cost effective to pay people to take their power than it is to shut off their plant. Shutting down a big plant is an event, and it takes a while to get them back running. Sometimes, shutting them down doesn't make sense.
  - VLM 13y ago
    Also about ten percent of the heat energy is released later on, delayed, decay heat and all that. So there is no off switch. If you were running at 3000 MWt, 5 minutes after you scram you still have to do "something" with 300 MW of heat, and you don't want to have to rely on just one diesel. So the feds require multiple sources of power to operate, one of which is usually the diesel and one is the the grid. Lets say your control and cooling systems require 5% of the heat they handle, that means your 3 GWt nuke would require an absolute minimum of 15 MWe to spin down. Or four if you want to run off grid so you've got two completely independent sources of power each with a 24x7 hot backup (I believe no one ever took the NRC up on that offer, but I could be wrong)
ChuckMcM 13y ago
This was one of the more interesting topics in my EE classes on "high power" systems. We toured a gas plant in Long Beach California which had 'internal black start' capability. Sloshing all that power around is a complex business and fraught with danger. Since I didn't expect to deal with much over 5V DC I pretty much ignored the boring bits (only to have them come back to haunt me when provisioning power in data centers.)
- sillysaurus 13y ago
  Sloshing all that power around is a complex business and fraught with danger. Why's that?
  - anthonyb 13y ago
    Because you're dealing with enough power to run a city. At a minimum thousands of kV and/or Amps. If something fails, all that energy has to go somewhere...
    - sillysaurus 13y ago
      Yes, obviously. I was prompting someone to provide more detail than that. E.g. what types of things can fail, what procedures have been put into place to mitigate the risk, examples of failures, or perhaps an interesting story or two.
      - mpyne 13y ago
        At the Prototype reactor site I qualified on there was a pretty impressive tale of a student who managed to try to bring a turbogenerator onto the electrical distribution system approximately 180 degrees out-of-phase. The resultant current surge generated enough force and torque to physically lift the turbogenerator off of the deck before the breaker tripped. The amazing thing is that somehow the steam piping didn't rupture in the process. Next year the aptly-named "sync check" modification was installed to prevent shutting the circuit breaker unless the two buses had approximately equal phase.
mrmagooey 13y ago
Australia's energy regulator (http://www.aemo.com.au/ http://www.aemo.com.au/) runs a separate pricing market (ancillary) for producers who are able to provide black start capability to the network, amongst other things like frequency regulation (I think...).
- mschaef 13y ago
  I can't speak for Australia, but I know that both are true for US pose markets. Power is a big part of what's sold, but there are many other markets too. Black start services, generation capacity, and frequency regulation, just to name a few. Part of the key to serving electrical demand is having a balanced mix of generation to serve your load. Some units are better running flat out, some are better for brief periods at peak demand, and some are good at quickly taking up the slack if another unit fails. Different power markets exist within the same geographical footprint to ensure that all these types of needs (and more) are met. (24 hours a day, 7 days a week, and into the foreseeable future.)
mpyne 13y ago
For fun, consider the question of how you'd "black start" from a loss of all AC power on a submerged nuclear submarine? :)
- brk 13y ago
  "Carefully".
- ultimoo 13y ago
  I'm certain nuclear power submarines have two nuclear generators always running to prevent this from happening. I also think they may have a diesel powered generator for bootstrapping.
  - joezydeco 13y ago
    That was the most interesting part of this article. Even the largest power plant comes down to a simple 12V battery needed to bootstrap the first generator.
    - CamperBob2 13y ago
      Similarly, it's fun to realize that the entire 27-km Large Hadron Collider "runs" on a small bottle of hydrogen that you could hold in your hand. http://void.printf.net/~conor/sa/LHCb/LHCfuel.jpg http://void.printf.net/~conor/sa/LHCb/LHCfuel.jpg Without that insignificant-looking bottle the whole machine would have nothing to do. (Edit: I do have to wonder how wise it is to paint a bottle of hydrogen to look like a fire extinguisher.)
      - jrabone 13y ago
        Gas bottle colour codes and fire extinguisher colour codes are two distinct namespaces... Here's a handy chart: http://www.ior.org.uk/ior_/images/pdf/se/New%20Colour%20ID%20Chart.pdf http://www.ior.org.uk/ior_/images/pdf/se/New%20Colour%20ID%2...
        13y ago
femto 13y ago
Is Wikipedia's statement that hydro stations require an external source for field excitation correct? I thought it was possible,to start a hydro generator by "self-excitation". When a generator stops, there is typically a small residual permanent magnetic field left, due to hysteresis. This small field may be used to "bootstrap" the generator, whereby on initial spin up a small current is generated, which may then be fed back to the field coil, further exciting the generator's field and increasing the output, until full capacity is reached. All that is then required is a method of opening the penstock, which can presumably be hand cranked?
- mpyne 13y ago
  Permanent magnet excitation is a possible way to generate the required field flux for a generator, but it's not a reliable way. If the permanent magnetic field isn't strong enough you can't even generate enough voltage to power-up the excitation circuit at all, and that's the circuit which would feed the current back in. So whether this is feasible or not depends on the generator design.
  - femto 13y ago
    I've got memories of some of the Snowy Mountains scheme's hydroelectric generators being designed to start though self-excitation. Wikipedia also has a bit about it [1]. It seems that there is usually a backup facility to run a DC current though the field winding before starting, thus magnetising the magnetic paths, for when the residual field has decayed too much. That backs up your comments about reliability. [1] http://en.wikipedia.org/wiki/Self-excitation http://en.wikipedia.org/wiki/Self-excitation
    - jacquesm 13y ago
      Residual flux is usually enough to start, but if you lose all flux for some reason (when the core is completely demagnetize) zapping it with DC can help restore it.
- deleted 13y ago
  [deleted]
whtrbt 13y ago
Noted for post-apocalypse.
hayksaakian 13y ago
Was there something in current events that prompted the rise of this post? I didn't realize posting links to encyclopedia articles qualified as "hacker news". While I think the discussion is an interesting one, it's still odd to see a random wikipedia article on the front page of HN
- anthonyb 13y ago
  One of my projects at the moment is to make a hand cranked USB power source. I stumbled across this while Googling for "stepper motor power generator" or something like that. It looked interesting, so I submitted it.
  - hayksaakian 13y ago
    This makes the discussion much more interesting to me. Thanks for the context.
- nitrogen 13y ago
  See my response to a similar statement in another thread: https://news.ycombinator.com/item?id=5630031 https://news.ycombinator.com/item?id=5630031 Hacker News isn't just about news, it's about learning and community. I, for one, would like to see more random Wikipedia articles on HN.
  - MBCook 13y ago
    I like seeing this kind of stuff too, but it can be nice to see some context for how someone ran across it (which anthonyb provided in a sibling comment to yours).
- VLM 13y ago
  "I didn't realize posting links to encyclopedia articles qualified as "hacker news"." If you actually have to be told this, I don't know what to say, but the analogy is if your virtualization system can't boot without working DHCP and DNS, you've got a big problem if you virtualize your DHCP and DNS. This is obvious. The more likely failure mode is some goofy homemade thing. Like you can't boot any server including the database server unless the LDAP backend can succesfully talk to the database of user info, but you can't talk to the database unless its already booted, so..
justinph 13y ago
Does this happen often? I suppose every time a plant gets shut down for maintenance, but I don't see mention of catastrophic failures necessitating many black starts.
lmm 13y ago
I think I remember reading that the phone system has nothing in place to do the equivalent - all the equipment relies on getting its code from the rest of the network, so if the entire phone network ever fell over there's no procedure to start it again. Anyone know one way or the other?
losethos 13y ago
1993, I had real-mode DOS I made a TASM application that changed to protected mode and echoed keyboard to screen, with multitasking. 2003, I resurrected the project. I stored files as data in my binary and compiled them with my interpretor. I converted more and more to C+. I made an assembler, I was self-hosting. http://web.archive.org/web/20040606212724/http://www.simstructure.hare.com/OS.htm http://web.archive.org/web/20040606212724/http://www.simstru... I installed real-mode FreeDOS. I got the linux floppy code, I booted from floppy. I wrote ATA code. I removed floppy code. God says... shall lie down, and none shall make them afraid. 17:3 The fortress also shall cease from Ephraim, and the kingdom from Damascus, and the remnant of Syria: they shall be as the glory of the children of Israel, saith the LORD of hosts. 17:4 And in that day it shall come to pass, that the glory of Jacob shall be made thin, and the fatness of his flesh shall wax lean. 17:5 And it shall be as when the harvestman gathereth the corn, and reapeth the ears with his arm; and it shall be as he that gathereth ears in the valley of Rephaim. 17:6 Yet gleaning grapes shall be left in it, as the shaking of an olive tree, two or three berries in the top of the uppermost bough, four or five in the outmost fruitful branches thereof, saith the LORD God of Israel.
Mvandenbergh 13y ago
Also important for black start capability are back-up batteries for the the switching equipment. If those run out, then you won't be able to reconfigure your network topology while bringing it up. Doing that manually takes a lot longer and could add days to a black-out.
iso8859-1 13y ago
Here's a video of what used to be the world's largest diesel engine, used for black starts if I remember correctly: Built by Burmeister & Wain[1] , located at H.C. Ørstedværket [2]: https://www.youtube.com/watch?v=jPouLq3yZI8 https://www.youtube.com/watch?v=jPouLq3yZI8 Maybe a diesel engine of this size was required since we don't have much hydro power in Denmark (the article suggests starting a hydroelectric generating station first). [1]: http://en.wikipedia.org/wiki/Burmeister_%26_Wain http://en.wikipedia.org/wiki/Burmeister_%26_Wain [2]: http://en.wikipedia.org/wiki/H._C._%C3%98rsted_Power_Station http://en.wikipedia.org/wiki/H._C._%C3%98rsted_Power_Station
- jacquesm 13y ago
  And here is the current largest: http://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4-Sulzer_RTA96-C http://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4-Sulzer_RTA96...
noxryan 13y ago
This reminds me of how turbine aircraft usually start their engines. The battery on these aircraft are used to start the APU (Auxiliary Power Unit) which then starts the main engines. The APU is basically a generator, often in the tail of the aircraft. https://en.wikipedia.org/wiki/Auxiliary_power_unit https://en.wikipedia.org/wiki/Auxiliary_power_unit

289 points by anthonyb 13y ago

sp332 13y ago

I was wondering why nuclear plants require so much power to start up, when really you can't "shut off" uranium's power-generation ability. I guess it would have to do with powering up all the safety and management systems around the generator?

aiiane 13y ago
Uranium (or other radioactive materials) don't directly generate much electricity - they mostly generate heat. Most nuclear power plants generate electricity by having that heat turn water into steam, which is then used to power steam turbines that actually drive the generator coils. Of course, in order to do this, you have to be able to pump water into the reactor to be turned into steam, and that pumping requires power. So yes, while you definitely need power for the safety/management equipment, the major bootstrap issue is almost certainly all of the power necessary for the pumps.
- mseebach 13y ago
  The article touches on this: Generating plants using steam turbines require station service power of up to 10% of their capacity for boiler feedwater pumps, boiler forced-draft combustion air blowers, and for fuel preparation.
mschaef 13y ago
Modern nuclear plants have two cascaded cooling loops and run at about 33% efficiency. This means that a 1000MW plant has 3000MW of thermal energy to manage at full load and 2000MW of energy to dissipate safely. The systems to do this take a great deal of power to run, so can't be bootstrapped off of batteries. Also interesting is that power prices will occasionally go negative in cases where there's a 'surplus' of generation. What's happening in these cases is that generation owners are making the judgement that its more cost effective to pay people to take their power than it is to shut off their plant. Shutting down a big plant is an event, and it takes a while to get them back running. Sometimes, shutting them down doesn't make sense.
- VLM 13y ago
  Also about ten percent of the heat energy is released later on, delayed, decay heat and all that. So there is no off switch. If you were running at 3000 MWt, 5 minutes after you scram you still have to do "something" with 300 MW of heat, and you don't want to have to rely on just one diesel. So the feds require multiple sources of power to operate, one of which is usually the diesel and one is the the grid. Lets say your control and cooling systems require 5% of the heat they handle, that means your 3 GWt nuke would require an absolute minimum of 15 MWe to spin down. Or four if you want to run off grid so you've got two completely independent sources of power each with a 24x7 hot backup (I believe no one ever took the NRC up on that offer, but I could be wrong)

ChuckMcM 13y ago

This was one of the more interesting topics in my EE classes on "high power" systems. We toured a gas plant in Long Beach California which had 'internal black start' capability. Sloshing all that power around is a complex business and fraught with danger. Since I didn't expect to deal with much over 5V DC I pretty much ignored the boring bits (only to have them come back to haunt me when provisioning power in data centers.)

sillysaurus 13y ago
Sloshing all that power around is a complex business and fraught with danger. Why's that?
- anthonyb 13y ago
  Because you're dealing with enough power to run a city. At a minimum thousands of kV and/or Amps. If something fails, all that energy has to go somewhere...
  - sillysaurus 13y ago
    Yes, obviously. I was prompting someone to provide more detail than that. E.g. what types of things can fail, what procedures have been put into place to mitigate the risk, examples of failures, or perhaps an interesting story or two.
    - mpyne 13y ago
      At the Prototype reactor site I qualified on there was a pretty impressive tale of a student who managed to try to bring a turbogenerator onto the electrical distribution system approximately 180 degrees out-of-phase. The resultant current surge generated enough force and torque to physically lift the turbogenerator off of the deck before the breaker tripped. The amazing thing is that somehow the steam piping didn't rupture in the process. Next year the aptly-named "sync check" modification was installed to prevent shutting the circuit breaker unless the two buses had approximately equal phase.

mrmagooey 13y ago

Australia's energy regulator (http://www.aemo.com.au/ http://www.aemo.com.au/) runs a separate pricing market (ancillary) for producers who are able to provide black start capability to the network, amongst other things like frequency regulation (I think...).

mschaef 13y ago
I can't speak for Australia, but I know that both are true for US pose markets. Power is a big part of what's sold, but there are many other markets too. Black start services, generation capacity, and frequency regulation, just to name a few. Part of the key to serving electrical demand is having a balanced mix of generation to serve your load. Some units are better running flat out, some are better for brief periods at peak demand, and some are good at quickly taking up the slack if another unit fails. Different power markets exist within the same geographical footprint to ensure that all these types of needs (and more) are met. (24 hours a day, 7 days a week, and into the foreseeable future.)

mpyne 13y ago

For fun, consider the question of how you'd "black start" from a loss of all AC power on a submerged nuclear submarine? :)

brk 13y ago
"Carefully".
ultimoo 13y ago
I'm certain nuclear power submarines have two nuclear generators always running to prevent this from happening. I also think they may have a diesel powered generator for bootstrapping.
- joezydeco 13y ago
  That was the most interesting part of this article. Even the largest power plant comes down to a simple 12V battery needed to bootstrap the first generator.
  - CamperBob2 13y ago
    Similarly, it's fun to realize that the entire 27-km Large Hadron Collider "runs" on a small bottle of hydrogen that you could hold in your hand. http://void.printf.net/~conor/sa/LHCb/LHCfuel.jpg http://void.printf.net/~conor/sa/LHCb/LHCfuel.jpg Without that insignificant-looking bottle the whole machine would have nothing to do. (Edit: I do have to wonder how wise it is to paint a bottle of hydrogen to look like a fire extinguisher.)
    - jrabone 13y ago
      Gas bottle colour codes and fire extinguisher colour codes are two distinct namespaces... Here's a handy chart: http://www.ior.org.uk/ior_/images/pdf/se/New%20Colour%20ID%20Chart.pdf http://www.ior.org.uk/ior_/images/pdf/se/New%20Colour%20ID%2...
      - 13y ago

femto 13y ago

Is Wikipedia's statement that hydro stations require an external source for field excitation correct? I thought it was possible,to start a hydro generator by "self-excitation". When a generator stops, there is typically a small residual permanent magnetic field left, due to hysteresis. This small field may be used to "bootstrap" the generator, whereby on initial spin up a small current is generated, which may then be fed back to the field coil, further exciting the generator's field and increasing the output, until full capacity is reached. All that is then required is a method of opening the penstock, which can presumably be hand cranked?

mpyne 13y ago
Permanent magnet excitation is a possible way to generate the required field flux for a generator, but it's not a reliable way. If the permanent magnetic field isn't strong enough you can't even generate enough voltage to power-up the excitation circuit at all, and that's the circuit which would feed the current back in. So whether this is feasible or not depends on the generator design.
- femto 13y ago
  I've got memories of some of the Snowy Mountains scheme's hydroelectric generators being designed to start though self-excitation. Wikipedia also has a bit about it [1]. It seems that there is usually a backup facility to run a DC current though the field winding before starting, thus magnetising the magnetic paths, for when the residual field has decayed too much. That backs up your comments about reliability. [1] http://en.wikipedia.org/wiki/Self-excitation http://en.wikipedia.org/wiki/Self-excitation
  - jacquesm 13y ago
    Residual flux is usually enough to start, but if you lose all flux for some reason (when the core is completely demagnetize) zapping it with DC can help restore it.
deleted 13y ago
[deleted]

whtrbt 13y ago

Noted for post-apocalypse.

hayksaakian 13y ago

Was there something in current events that prompted the rise of this post? I didn't realize posting links to encyclopedia articles qualified as "hacker news". While I think the discussion is an interesting one, it's still odd to see a random wikipedia article on the front page of HN

anthonyb 13y ago
One of my projects at the moment is to make a hand cranked USB power source. I stumbled across this while Googling for "stepper motor power generator" or something like that. It looked interesting, so I submitted it.
- hayksaakian 13y ago
  This makes the discussion much more interesting to me. Thanks for the context.
nitrogen 13y ago
See my response to a similar statement in another thread: https://news.ycombinator.com/item?id=5630031 https://news.ycombinator.com/item?id=5630031 Hacker News isn't just about news, it's about learning and community. I, for one, would like to see more random Wikipedia articles on HN.
- MBCook 13y ago
  I like seeing this kind of stuff too, but it can be nice to see some context for how someone ran across it (which anthonyb provided in a sibling comment to yours).
VLM 13y ago
"I didn't realize posting links to encyclopedia articles qualified as "hacker news"." If you actually have to be told this, I don't know what to say, but the analogy is if your virtualization system can't boot without working DHCP and DNS, you've got a big problem if you virtualize your DHCP and DNS. This is obvious. The more likely failure mode is some goofy homemade thing. Like you can't boot any server including the database server unless the LDAP backend can succesfully talk to the database of user info, but you can't talk to the database unless its already booted, so..

justinph 13y ago

Does this happen often? I suppose every time a plant gets shut down for maintenance, but I don't see mention of catastrophic failures necessitating many black starts.

lmm 13y ago

I think I remember reading that the phone system has nothing in place to do the equivalent - all the equipment relies on getting its code from the rest of the network, so if the entire phone network ever fell over there's no procedure to start it again. Anyone know one way or the other?

losethos 13y ago

1993, I had real-mode DOS I made a TASM application that changed to protected mode and echoed keyboard to screen, with multitasking. 2003, I resurrected the project. I stored files as data in my binary and compiled them with my interpretor. I converted more and more to C+. I made an assembler, I was self-hosting. http://web.archive.org/web/20040606212724/http://www.simstructure.hare.com/OS.htm http://web.archive.org/web/20040606212724/http://www.simstru... I installed real-mode FreeDOS. I got the linux floppy code, I booted from floppy. I wrote ATA code. I removed floppy code. God says... shall lie down, and none shall make them afraid. 17:3 The fortress also shall cease from Ephraim, and the kingdom from Damascus, and the remnant of Syria: they shall be as the glory of the children of Israel, saith the LORD of hosts. 17:4 And in that day it shall come to pass, that the glory of Jacob shall be made thin, and the fatness of his flesh shall wax lean. 17:5 And it shall be as when the harvestman gathereth the corn, and reapeth the ears with his arm; and it shall be as he that gathereth ears in the valley of Rephaim. 17:6 Yet gleaning grapes shall be left in it, as the shaking of an olive tree, two or three berries in the top of the uppermost bough, four or five in the outmost fruitful branches thereof, saith the LORD God of Israel.

Mvandenbergh 13y ago

Also important for black start capability are back-up batteries for the the switching equipment. If those run out, then you won't be able to reconfigure your network topology while bringing it up. Doing that manually takes a lot longer and could add days to a black-out.

iso8859-1 13y ago

Here's a video of what used to be the world's largest diesel engine, used for black starts if I remember correctly: Built by Burmeister & Wain[1] , located at H.C. Ørstedværket [2]: https://www.youtube.com/watch?v=jPouLq3yZI8 https://www.youtube.com/watch?v=jPouLq3yZI8 Maybe a diesel engine of this size was required since we don't have much hydro power in Denmark (the article suggests starting a hydroelectric generating station first). [1]: http://en.wikipedia.org/wiki/Burmeister_%26_Wain http://en.wikipedia.org/wiki/Burmeister_%26_Wain [2]: http://en.wikipedia.org/wiki/H._C._%C3%98rsted_Power_Station http://en.wikipedia.org/wiki/H._C._%C3%98rsted_Power_Station

jacquesm 13y ago
And here is the current largest: http://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4-Sulzer_RTA96-C http://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4-Sulzer_RTA96...

noxryan 13y ago

This reminds me of how turbine aircraft usually start their engines. The battery on these aircraft are used to start the APU (Auxiliary Power Unit) which then starts the main engines. The APU is basically a generator, often in the tail of the aircraft. https://en.wikipedia.org/wiki/Auxiliary_power_unit https://en.wikipedia.org/wiki/Auxiliary_power_unit