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Groups > sci.electronics.design > #446378 > unrolled thread
| Started by | Pimpom <pimpom@invalid.com> |
|---|---|
| First post | 2017-02-06 11:22 +0530 |
| Last post | 2017-02-09 04:57 -0500 |
| Articles | 20 on this page of 119 — 31 participants |
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OT: Current standard for watch precision Pimpom <pimpom@invalid.com> - 2017-02-06 11:22 +0530
Re: OT: Current standard for watch precision Phil Allison <pallison49@gmail.com> - 2017-02-05 22:13 -0800
Re: OT: Current standard for watch precision Pimpom <Pimpom@invalid.com> - 2017-02-06 17:15 +0530
Re: OT: Current standard for watch precision Phil Allison <pallison49@gmail.com> - 2017-02-06 05:11 -0800
Re: OT: Current standard for watch precision Pimpom <Pimpom@invalid.com> - 2017-02-06 19:30 +0530
Re: OT: Current standard for watch precision Phil Allison <pallison49@gmail.com> - 2017-02-06 06:33 -0800
Re: OT: Current standard for watch precision nub12 <nub12@null.com> - 2017-02-07 07:57 +0800
Re: OT: Current standard for watch precision Robert Baer <robertbaer@localnet.com> - 2017-02-08 20:06 -0800
Re: OT: Current standard for watch precision Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-02-06 20:16 +0200
Re: OT: Current standard for watch precision Pimpom <Pimpom@invalid.com> - 2017-02-07 00:12 +0530
Re: OT: Current standard for watch precision Don Y <blockedofcourse@foo.invalid> - 2017-02-06 11:58 -0700
Re: OT: Current standard for watch precision Jasen Betts <jasen@xnet.co.nz> - 2017-02-07 05:50 +0000
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-07 02:43 -0500
Re: OT: Current standard for watch precision Pimpom <Pimpom@invalid.com> - 2017-02-07 14:53 +0530
Re: OT: Current standard for watch precision krw@notreal.com - 2017-02-07 12:32 -0500
Re: OT: Current standard for watch precision Phil Allison <pallison49@gmail.com> - 2017-02-07 02:33 -0800
Re: OT: Current standard for watch precision upsidedown@downunder.com - 2017-02-07 17:56 +0200
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-07 17:32 -0500
Re: OT: Current standard for watch precision Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-07 14:52 -0800
Re: OT: Current standard for watch precision upsidedown@downunder.com - 2017-02-08 10:25 +0200
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-08 03:37 -0500
Re: OT: Current standard for watch precision Martin Brown <|||newspam|||@nezumi.demon.co.uk> - 2017-02-08 09:01 +0000
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-08 05:24 -0500
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-08 09:08 -0800
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-08 16:04 -0500
Re: OT: Current standard for watch precision Clifford Heath <no.spam@please.net> - 2017-02-09 08:12 +1100
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-08 17:28 -0500
Re: OT: Current standard for watch precision pcdhobbs@gmail.com - 2017-02-08 16:19 -0800
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-09 00:36 -0500
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-09 00:38 -0500
Re: OT: Current standard for watch precision Clifford Heath <no.spam@please.net> - 2017-02-09 18:39 +1100
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-09 04:16 -0500
Re: OT: Current standard for watch precision Martin Brown <|||newspam|||@nezumi.demon.co.uk> - 2017-02-09 09:46 +0000
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-09 05:03 -0500
Re: OT: Current standard for watch precision Jeroen Belleman <jeroen@nospam.please> - 2017-02-09 11:45 +0100
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-09 07:12 -0500
Re: OT: Current standard for watch precision Jeroen Belleman <jeroen@nospam.please> - 2017-02-09 13:31 +0100
Re: OT: Current standard for watch precision Martin Brown <|||newspam|||@nezumi.demon.co.uk> - 2017-02-09 12:14 +0000
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-09 07:25 -0500
Re: OT: Current standard for watch precision Martin Brown <|||newspam|||@nezumi.demon.co.uk> - 2017-02-10 09:17 +0000
Re: OT: Current standard for watch precision Jeroen Belleman <jeroen@nospam.please> - 2017-02-10 10:45 +0100
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-10 21:56 -0500
Re: OT: Current standard for watch precision Jasen Betts <jasen@xnet.co.nz> - 2017-02-11 02:06 +0000
Re: OT: Current standard for watch precision krw@notreal.com - 2017-02-10 22:24 -0500
Re: OT: Current standard for watch precision Jasen Betts <jasen@xnet.co.nz> - 2017-02-11 01:54 +0000
Re: OT: Current standard for watch precision Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-10 18:10 -0800
Re: OT: Current standard for watch precision Cursitor Doom <curd@notformail.com> - 2017-02-08 23:34 +0000
Re: OT: Current standard for watch precision Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-08 15:49 -0800
Re: OT: Current standard for watch precision pcdhobbs@gmail.com - 2017-02-08 15:55 -0800
Re: OT: Current standard for watch precision Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-08 16:08 -0800
Re: OT: Current standard for watch precision Ralph Barone <ralph@invalid.com> - 2017-02-09 03:24 +0000
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-08 20:34 -0800
Re: OT: Current standard for watch precision Tim Wescott <tim@seemywebsite.com> - 2017-02-08 23:26 -0600
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-08 23:28 -0800
Re: OT: Current standard for watch precision Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> - 2017-02-09 00:48 -0500
Re: OT: Current standard for watch precision George Herold <gherold@teachspin.com> - 2017-02-09 06:52 -0800
Re: OT: Current standard for watch precision krw@notreal.com - 2017-02-09 20:37 -0500
Re: OT: Current standard for watch precision Cursitor Doom <curd@notformail.com> - 2017-02-10 17:11 +0000
Re: OT: Current standard for watch precision upsidedown@downunder.com - 2017-02-09 23:13 +0200
Re: OT: Current standard for watch precision krw@notreal.com - 2017-02-08 20:17 -0500
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-08 19:29 -0800
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-08 20:16 -0800
Re: OT: Current standard for watch precision Martin Brown <|||newspam|||@nezumi.demon.co.uk> - 2017-02-08 17:13 +0000
Re: OT: Current standard for watch precision kevin93 <kevin@whitedigs.com> - 2017-02-08 12:54 -0800
Re: OT: Current standard for watch precision krw@notreal.com - 2017-02-08 12:35 -0500
Re: OT: Current standard for watch precision Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-08 09:50 -0800
Re: OT: Current standard for watch precision krw@notreal.com - 2017-02-08 13:14 -0500
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-08 11:35 -0800
Re: OT: Current standard for watch precision upsidedown@downunder.com - 2017-02-08 23:16 +0200
Re: OT: Current standard for watch precision Jeroen Belleman <jeroen@nospam.please> - 2017-02-09 09:59 +0100
Re: OT: Current standard for watch precision Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-08 09:41 -0800
Re: OT: Current standard for watch precision krw@notreal.com - 2017-02-08 13:15 -0500
Re: OT: Current standard for watch precision Jasen Betts <jasen@xnet.co.nz> - 2017-02-11 01:46 +0000
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-10 22:12 -0500
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-09 15:25 -0800
Re: OT: Current standard for watch precision Clifford Heath <no.spam@please.net> - 2017-02-10 10:38 +1100
Re: OT: Current standard for watch precision bill.sloman@ieee.org - 2017-02-09 17:42 -0800
Re: OT: Current standard for watch precision Jeroen Belleman <jeroen@nospam.please> - 2017-02-08 11:01 +0100
Re: OT: Current standard for watch precision Jasen Betts <jasen@xnet.co.nz> - 2017-02-11 04:06 +0000
Re: OT: Current standard for watch precision krw@notreal.com - 2017-02-07 21:02 -0500
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-07 10:24 -0800
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-07 10:48 -0800
Re: OT: Current standard for watch precision George Herold <gherold@teachspin.com> - 2017-02-07 11:12 -0800
Re: OT: Current standard for watch precision Mikko OH2HVJ <mikko.syrjalahti@nospam.fi> - 2017-02-08 09:33 +0200
Re: OT: Current standard for watch precision George Herold <gherold@teachspin.com> - 2017-02-08 06:31 -0800
Re: OT: Current standard for watch precision Martin Brown <|||newspam|||@nezumi.demon.co.uk> - 2017-02-07 09:58 +0000
Re: OT: Current standard for watch precision Robert Baer <robertbaer@localnet.com> - 2017-02-08 20:00 -0800
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-05 23:01 -0800
Re: OT: Current standard for watch precision mike <ham789@netzero.net> - 2017-02-06 03:21 -0800
Re: OT: Current standard for watch precision Pimpom <Pimpom@invalid.com> - 2017-02-06 17:25 +0530
Re: Current standard for watch precision "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-06 06:57 -0600
Re: Current standard for watch precision Pimpom <Pimpom@invalid.com> - 2017-02-06 19:10 +0530
Re: Current standard for watch precision "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-06 08:13 -0600
Re: Current standard for watch precision Pimpom <Pimpom@invalid.com> - 2017-02-06 21:04 +0530
Re: Current standard for watch precision Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> - 2017-02-06 09:30 -0500
Re: Current standard for watch precision George Herold <gherold@teachspin.com> - 2017-02-06 06:56 -0800
Re: Current standard for watch precision Robert Baer <robertbaer@localnet.com> - 2017-02-08 20:11 -0800
Re: Current standard for watch precision Don Y <blockedofcourse@foo.invalid> - 2017-02-06 12:04 -0700
Re: Current standard for watch precision Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-06 14:58 -0700
Re: Current standard for watch precision Don Y <blockedofcourse@foo.invalid> - 2017-02-06 15:21 -0700
Re: Current standard for watch precision Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-06 16:06 -0700
Re: Current standard for watch precision Don Y <blockedofcourse@foo.invalid> - 2017-02-06 17:19 -0700
Re: Current standard for watch precision Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-06 17:52 -0700
Re: Current standard for watch precision Don Y <blockedofcourse@foo.invalid> - 2017-02-06 17:55 -0700
Re: Current standard for watch precision krw@notreal.com - 2017-02-06 21:44 -0500
Re: Current standard for watch precision Robert Baer <robertbaer@localnet.com> - 2017-02-08 20:04 -0800
Re: OT: Current standard for watch precision Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> - 2017-02-06 09:06 -0500
Re: OT: Current standard for watch precision Pimpom <Pimpom@invalid.com> - 2017-02-06 21:04 +0530
Re: OT: Current standard for watch precision TTman <pcw1.cad@ntlworld.com> - 2017-02-06 14:31 +0000
Re: OT: Current standard for watch precision Clifford Heath <no.spam@please.net> - 2017-02-07 08:54 +1100
Re: OT: Current standard for watch precision Tim Wescott <seemywebsite@myfooter.really> - 2017-02-06 17:33 -0600
Re: OT: Current standard for watch precision krw@notreal.com - 2017-02-06 21:23 -0500
Re: OT: Current standard for watch precision prairiesky <outgoing.server@mozilla.com> - 2017-02-06 23:00 -0800
Re: OT: Current standard for watch precision Cursitor Doom <curd@notformail.com> - 2017-02-07 18:29 +0000
Re: OT: Current standard for watch precision Robert Baer <robertbaer@localnet.com> - 2017-02-08 19:59 -0800
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-09 00:48 -0500
Re: OT: Current standard for watch precision Tim Wescott <tim@seemywebsite.com> - 2017-02-08 23:54 -0600
Re: OT: Current standard for watch precision Tim Wescott <tim@seemywebsite.com> - 2017-02-09 00:00 -0600
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-09 04:57 -0500
Page 2 of 6 — ← Prev page 1 [2] 3 4 5 6 Next page →
| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-02-08 03:37 -0500 |
| Message-ID | <o7el8a$doe$2@dont-email.me> |
| In reply to | #446757 |
On 2/8/2017 3:25 AM, upsidedown@downunder.com wrote: > On Tue, 7 Feb 2017 14:52:09 -0800 (PST), Lasse Langwadt Christensen > <langwadt@fonz.dk> wrote: > >> Den tirsdag den 7. februar 2017 kl. 23.32.16 UTC+1 skrev rickman: >>> On 2/7/2017 10:56 AM, upsidedown@downunder.com wrote: >>>> On Tue, 7 Feb 2017 02:43:33 -0500, rickman <gnuarm@gmail.com> wrote: >>>> >>>>> >>>>> I also remember building a clock with a vacuum florescent display with a >>>>> trimmer. I was adjusting it by beating a 60 Hz output against the power >>>>> line. I could get it very, very close, but then ten or fifteen minutes >>>>> later it would drift again! It took me awhile before I realized that >>>>> wasn't the clock, it was the power line. lol >>>>> >>>>> Does the power line still drift like that? Is there a reason why it >>>>> would in this day with the many sources of accurate timing available? >>>>> I'd expect the many generators could do a much better job of not running >>>>> up and down in frequency so much, or is this an inherent aspect of a >>>>> widely distributed network? >>>> >>>> This is exactly how synchronous AC generators are operated. A changing >>>> load will slightly change the frequency and the primary mover (water, >>>> steam) are adjusted accordingly. The variation is small and the error >>>> in a mains synchronized clocks is usually below 10 to 15 s. During the >>>> night, the network is running slightly above nominal frequency, in >>>> order to catch up before the next morning. >>> >>> I think there is more to it than that. We aren't talking about a single >>> generator, we are dealing with a country wide network that has to stay >>> very close to in phase. I would be *very* surprised to find the grid >>> would drift by multiple seconds within a day. >> >> on the page Jeff linked to it says they can catch up ~17 seconds a day, >> once they get 20 seconds out of sync >> >> and it is just country wide, the synchronous grid of Continental Europe >> 667 gigawatts in 20 some countries > > There are thousands of generators connected in parallel and the > fluctuating frequency ensures that there are proper load sharing > between generators. This method has been used for more than a century. So how is the average frequency maintained? What actually controls the long term frequency of the grid? If it were just the load sharing driving the frequency up and down as the loads and generators vary, the frequency would wander with no fixed average. -- Rick C
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| From | Martin Brown <|||newspam|||@nezumi.demon.co.uk> |
|---|---|
| Date | 2017-02-08 09:01 +0000 |
| Message-ID | <o7emp2$vef$1@gioia.aioe.org> |
| In reply to | #446758 |
On 08/02/2017 08:37, rickman wrote: > On 2/8/2017 3:25 AM, upsidedown@downunder.com wrote: >> On Tue, 7 Feb 2017 14:52:09 -0800 (PST), Lasse Langwadt Christensen >> <langwadt@fonz.dk> wrote: >> >>> on the page Jeff linked to it says they can catch up ~17 seconds a day, >>> once they get 20 seconds out of sync >>> >>> and it is just country wide, the synchronous grid of Continental Europe >>> 667 gigawatts in 20 some countries >> >> There are thousands of generators connected in parallel and the >> fluctuating frequency ensures that there are proper load sharing >> between generators. This method has been used for more than a century. > > So how is the average frequency maintained? What actually controls the > long term frequency of the grid? If it were just the load sharing > driving the frequency up and down as the loads and generators vary, the > frequency would wander with no fixed average. The long term average is very carefully maintained by running the grid faster usually at night to catch up when the load is lowest - a quirk that used to annoy astronomers back in the days when synchronous 60Hz motors were used on some telescope drives. If you watch the realtime grid frequency display at times of peak load on for example UK gridwatch you will see the relation between load and frequency. They try never to get more than 0.2Hz out for an extended period and will bring in fast generators like the pumped hydro storage and gas turbines if it does or typically if peak load is anticipated. http://www.gridwatch.templar.co.uk/ Big football match half time is particularly hard on the grid at this time of year as everyone goes to put the kettle on at once and load is already pretty close to the upper limit. Not much margin on UK capacity. -- Regards, Martin Brown
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| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-02-08 05:24 -0500 |
| Message-ID | <o7erho$16l$2@dont-email.me> |
| In reply to | #446759 |
On 2/8/2017 4:01 AM, Martin Brown wrote: > On 08/02/2017 08:37, rickman wrote: >> On 2/8/2017 3:25 AM, upsidedown@downunder.com wrote: >>> On Tue, 7 Feb 2017 14:52:09 -0800 (PST), Lasse Langwadt Christensen >>> <langwadt@fonz.dk> wrote: >>> >>>> on the page Jeff linked to it says they can catch up ~17 seconds a day, >>>> once they get 20 seconds out of sync >>>> >>>> and it is just country wide, the synchronous grid of Continental Europe >>>> 667 gigawatts in 20 some countries >>> >>> There are thousands of generators connected in parallel and the >>> fluctuating frequency ensures that there are proper load sharing >>> between generators. This method has been used for more than a century. >> >> So how is the average frequency maintained? What actually controls the >> long term frequency of the grid? If it were just the load sharing >> driving the frequency up and down as the loads and generators vary, the >> frequency would wander with no fixed average. > > The long term average is very carefully maintained by running the grid > faster usually at night to catch up when the load is lowest - a quirk > that used to annoy astronomers back in the days when synchronous 60Hz > motors were used on some telescope drives. If you watch the realtime > grid frequency display at times of peak load on for example UK gridwatch > you will see the relation between load and frequency. > > They try never to get more than 0.2Hz out for an extended period and > will bring in fast generators like the pumped hydro storage and gas > turbines if it does or typically if peak load is anticipated. > > http://www.gridwatch.templar.co.uk/ > > Big football match half time is particularly hard on the grid at this > time of year as everyone goes to put the kettle on at once and load is > already pretty close to the upper limit. Not much margin on UK capacity. Yes, but *how* do they run the grid faster or slower? Also, *who* controls this? -- Rick C
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| From | Jeff Liebermann <jeffl@cruzio.com> |
|---|---|
| Date | 2017-02-08 09:08 -0800 |
| Message-ID | <kaim9clrvvpmlfoe33eehkpe7p1ugha1om@4ax.com> |
| In reply to | #446763 |
On Wed, 8 Feb 2017 05:24:35 -0500, rickman <gnuarm@gmail.com> wrote: >Yes, but *how* do they run the grid faster or slower? Also, *who* >controls this? This is cool. Crowd sourced utility frequency data: "FNET/GridEye Web Display. U.S. Frequency Gradient Map" <http://fnetpublic.utk.edu/gradientmap.html> (USA/Canada) <http://powerit.utk.edu/worldmap/> (World) Some detail on how it works: <http://fnetpublic.utk.edu> <https://en.wikipedia.org/wiki/FNET> Wikipedia article on Utility Freq: <https://en.wikipedia.org/wiki/Utility_frequency#Stability> Looks like it's run by the NERC: <https://en.wikipedia.org/wiki/North_American_Electric_Reliability_Corporation> but I couldn't find anything involving frequency control on their web pile. "How do power plants maintain a 60 Hz frequency?" <https://www.reddit.com/r/askscience/comments/1kpx0l/how_do_power_plants_maintain_a_60_hz_frequency/> My guess(tm) is the actual speed adjustment varies by the generator type. For solar, there's a DC to AC inverter which can be controlled electronically. For hydro, vary the flow rate to match the load. For steam power, vary the steam pressure to match the load. Since both the load and the flow/pressure affects the frequency, the steam pressure, flow rate, etc will need to track to considerable precision. There's also a proposal to eliminate the TEC (time error correction): "Time Error Correction and Reliability White Paper" <http://www.nerc.com/pa/Stand/Project%2020101422%20Phase%202%20of%20BARC%20%20BAL004%20DL/BAL-004-0_White_Paper_Clean_09242015.pdf> -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
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| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-02-08 16:04 -0500 |
| Message-ID | <o7g11k$frj$1@dont-email.me> |
| In reply to | #446797 |
On 2/8/2017 12:08 PM, Jeff Liebermann wrote: > On Wed, 8 Feb 2017 05:24:35 -0500, rickman <gnuarm@gmail.com> wrote: >> Yes, but *how* do they run the grid faster or slower? Also, *who* >> controls this? > > This is cool. Crowd sourced utility frequency data: > "FNET/GridEye Web Display. U.S. Frequency Gradient Map" > <http://fnetpublic.utk.edu/gradientmap.html> (USA/Canada) > <http://powerit.utk.edu/worldmap/> (World) > Some detail on how it works: > <http://fnetpublic.utk.edu> > <https://en.wikipedia.org/wiki/FNET> > > Wikipedia article on Utility Freq: > <https://en.wikipedia.org/wiki/Utility_frequency#Stability> > Looks like it's run by the NERC: > <https://en.wikipedia.org/wiki/North_American_Electric_Reliability_Corporation> > but I couldn't find anything involving frequency control on their web > pile. > > "How do power plants maintain a 60 Hz frequency?" > <https://www.reddit.com/r/askscience/comments/1kpx0l/how_do_power_plants_maintain_a_60_hz_frequency/> > > My guess(tm) is the actual speed adjustment varies by the generator > type. For solar, there's a DC to AC inverter which can be controlled > electronically. For hydro, vary the flow rate to match the load. For > steam power, vary the steam pressure to match the load. Since both > the load and the flow/pressure affects the frequency, the steam > pressure, flow rate, etc will need to track to considerable precision. > > There's also a proposal to eliminate the TEC (time error correction): > "Time Error Correction and Reliability White Paper" > <http://www.nerc.com/pa/Stand/Project%2020101422%20Phase%202%20of%20BARC%20%20BAL004%20DL/BAL-004-0_White_Paper_Clean_09242015.pdf> Thanks for all the links, but they don't actually explain the mechanism for how the various generators are adjusted to maintain the grid frequency. Someone else indicated in Europe there is a central point of measurement and once a day they send out orders to plant operators to adjust some control that causes the generator to exert force on the network. I suppose that creates an individually small, but in aggregate large force to drive the grid frequency. But that has to be separate from adjusting the generators for the varying loads. -- Rick C
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| From | Clifford Heath <no.spam@please.net> |
|---|---|
| Date | 2017-02-09 08:12 +1100 |
| Message-ID | <589b89c9$0$43766$c3e8da3$5e5e430d@news.astraweb.com> |
| In reply to | #446857 |
On 09/02/17 08:04, rickman wrote: > On 2/8/2017 12:08 PM, Jeff Liebermann wrote: >> On Wed, 8 Feb 2017 05:24:35 -0500, rickman <gnuarm@gmail.com> wrote: >>> Yes, but *how* do they run the grid faster or slower? Also, *who* >>> controls this? >> >> This is cool. Crowd sourced utility frequency data: >> "FNET/GridEye Web Display. U.S. Frequency Gradient Map" >> <http://fnetpublic.utk.edu/gradientmap.html> (USA/Canada) >> <http://powerit.utk.edu/worldmap/> (World) >> Some detail on how it works: >> <http://fnetpublic.utk.edu> >> <https://en.wikipedia.org/wiki/FNET> >> >> Wikipedia article on Utility Freq: >> <https://en.wikipedia.org/wiki/Utility_frequency#Stability> >> Looks like it's run by the NERC: >> <https://en.wikipedia.org/wiki/North_American_Electric_Reliability_Corporation> >> >> but I couldn't find anything involving frequency control on their web >> pile. >> >> "How do power plants maintain a 60 Hz frequency?" >> <https://www.reddit.com/r/askscience/comments/1kpx0l/how_do_power_plants_maintain_a_60_hz_frequency/> >> >> >> My guess(tm) is the actual speed adjustment varies by the generator >> type. For solar, there's a DC to AC inverter which can be controlled >> electronically. For hydro, vary the flow rate to match the load. For >> steam power, vary the steam pressure to match the load. Since both >> the load and the flow/pressure affects the frequency, the steam >> pressure, flow rate, etc will need to track to considerable precision. >> >> There's also a proposal to eliminate the TEC (time error correction): >> "Time Error Correction and Reliability White Paper" >> <http://www.nerc.com/pa/Stand/Project%2020101422%20Phase%202%20of%20BARC%20%20BAL004%20DL/BAL-004-0_White_Paper_Clean_09242015.pdf> >> > > Thanks for all the links, but they don't actually explain the mechanism > for how the various generators are adjusted to maintain the grid > frequency The generators will tend to phase lock by themselves because of the load. If you feed in more power (more steam, water, etc) then its phase will just move ahead slightly. Loss of lock would be disastrous.
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| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-02-08 17:28 -0500 |
| Message-ID | <o7g5vl$3l8$2@dont-email.me> |
| In reply to | #446863 |
On 2/8/2017 4:12 PM, Clifford Heath wrote: > On 09/02/17 08:04, rickman wrote: >> On 2/8/2017 12:08 PM, Jeff Liebermann wrote: >>> On Wed, 8 Feb 2017 05:24:35 -0500, rickman <gnuarm@gmail.com> wrote: >>>> Yes, but *how* do they run the grid faster or slower? Also, *who* >>>> controls this? >>> >>> This is cool. Crowd sourced utility frequency data: >>> "FNET/GridEye Web Display. U.S. Frequency Gradient Map" >>> <http://fnetpublic.utk.edu/gradientmap.html> (USA/Canada) >>> <http://powerit.utk.edu/worldmap/> (World) >>> Some detail on how it works: >>> <http://fnetpublic.utk.edu> >>> <https://en.wikipedia.org/wiki/FNET> >>> >>> Wikipedia article on Utility Freq: >>> <https://en.wikipedia.org/wiki/Utility_frequency#Stability> >>> Looks like it's run by the NERC: >>> <https://en.wikipedia.org/wiki/North_American_Electric_Reliability_Corporation> >>> >>> >>> but I couldn't find anything involving frequency control on their web >>> pile. >>> >>> "How do power plants maintain a 60 Hz frequency?" >>> <https://www.reddit.com/r/askscience/comments/1kpx0l/how_do_power_plants_maintain_a_60_hz_frequency/> >>> >>> >>> >>> My guess(tm) is the actual speed adjustment varies by the generator >>> type. For solar, there's a DC to AC inverter which can be controlled >>> electronically. For hydro, vary the flow rate to match the load. For >>> steam power, vary the steam pressure to match the load. Since both >>> the load and the flow/pressure affects the frequency, the steam >>> pressure, flow rate, etc will need to track to considerable precision. >>> >>> There's also a proposal to eliminate the TEC (time error correction): >>> "Time Error Correction and Reliability White Paper" >>> <http://www.nerc.com/pa/Stand/Project%2020101422%20Phase%202%20of%20BARC%20%20BAL004%20DL/BAL-004-0_White_Paper_Clean_09242015.pdf> >>> >>> >> >> Thanks for all the links, but they don't actually explain the mechanism >> for how the various generators are adjusted to maintain the grid >> frequency > > The generators will tend to phase lock by themselves because of > the load. If you feed in more power (more steam, water, etc) > then its phase will just move ahead slightly. Loss of lock would > be disastrous. That doesn't explain how the "herd" is controlled. -- Rick C
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| From | pcdhobbs@gmail.com |
|---|---|
| Date | 2017-02-08 16:19 -0800 |
| Message-ID | <7098daf1-d7bf-476e-9920-266316ebc9c1@googlegroups.com> |
| In reply to | #446888 |
>That doesn't explain how the "herd" is controlled. It's mostly large-scale rotating machinery with a lot of inertia. When the load exceeds the input, the 'herd' slows down. Thus you keep the system in balance by watching the frequency. Cheers Phil Hobbs
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| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-02-09 00:36 -0500 |
| Message-ID | <o7gv1a$uov$1@dont-email.me> |
| In reply to | #446924 |
On 2/8/2017 7:19 PM, pcdhobbs@gmail.com wrote: >> That doesn't explain how the "herd" is controlled. > > It's mostly large-scale rotating machinery with a lot of inertia. When the load exceeds the input, the 'herd' slows down. Thus you keep the system in balance by watching the frequency. That's not the question I'm asking. You have 10,000 people on a ship as oarsmen. None can really see the others, but they all can hear each other and they all chant the cadence as they paddle. It is *much* more effective if they all stroke together. There is no guy on deck with a drum, just the chorus of voices crying, "stroke, stroke,..." The pilot can talk to any of the oarsmen singly. Or maybe he has an intercom that lets him talk to them all. I don't know. If the pilot wants to speed up the boat, what does he do? That's what I'm asking about keeping the grid on sync with the time. How does the pilot control the oarsmen and how do the oarsmen keep in step but also nudge the stroke? -- Rick C
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| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-02-09 00:38 -0500 |
| Message-ID | <o7gv4g$uov$2@dont-email.me> |
| In reply to | #446973 |
On 2/9/2017 12:36 AM, rickman wrote: > On 2/8/2017 7:19 PM, pcdhobbs@gmail.com wrote: >>> That doesn't explain how the "herd" is controlled. >> >> It's mostly large-scale rotating machinery with a lot of inertia. When >> the load exceeds the input, the 'herd' slows down. Thus you keep the >> system in balance by watching the frequency. > > That's not the question I'm asking. > > You have 10,000 people on a ship as oarsmen. None can really see the > others, but they all can hear each other and they all chant the cadence > as they paddle. It is *much* more effective if they all stroke > together. There is no guy on deck with a drum, just the chorus of > voices crying, "stroke, stroke,..." > > The pilot can talk to any of the oarsmen singly. Or maybe he has an > intercom that lets him talk to them all. I don't know. > > If the pilot wants to speed up the boat, what does he do? > > That's what I'm asking about keeping the grid on sync with the time. How > does the pilot control the oarsmen and how do the oarsmen keep in step > but also nudge the stroke? Oh yeah, and dealing with varying loads in the boat and wind and waves... -- Rick C
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| From | Clifford Heath <no.spam@please.net> |
|---|---|
| Date | 2017-02-09 18:39 +1100 |
| Message-ID | <589c1ca5$0$29106$c3e8da3$38634283@news.astraweb.com> |
| In reply to | #446973 |
On 09/02/17 16:36, rickman wrote: > On 2/8/2017 7:19 PM, pcdhobbs@gmail.com wrote: >>> That doesn't explain how the "herd" is controlled. >> >> It's mostly large-scale rotating machinery with a lot of inertia. When >> the load exceeds the input, the 'herd' slows down. Thus you keep the >> system in balance by watching the frequency. > > That's not the question I'm asking. Yes, it is, but you still don't seem to understand why. > You have 10,000 people on a ship as oarsmen. None can really see the > others, but they all can hear each other and they all chant the cadence > as they paddle. It is *much* more effective if they all stroke > together. That's a terrible example that does not apply. The oarsmen must stroke together only because the oars would collide. Remove 2 of every three oars so there is room and each oarsman could stroke at whatever pace he chose. He could also choose how much actual work to do on each stroke too (as can each one when all are in sync of course). He can idle along, letting the passing water push the oar, or he can lean into it, and propel the boat. In a similar way, each generator can keep pace, however much power it is contributing. But if it contributes little power, its turbine will tend to run fast, pushing its phase ahead, which makes it contribute more power and so stay in a (slightly advanced) phase lock. Similarly if it falls behind; its power contribution falls until it's being dragged along by the grid, instead if pushed along by its turbine (like the rower letting the water push the oar). Each power station can in this way sense when all together are meeting the demand, or when they need to change, and each can change in the right direction on their own. Clifford Heath.
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| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-02-09 04:16 -0500 |
| Message-ID | <o7hbtm$9i$1@dont-email.me> |
| In reply to | #446984 |
On 2/9/2017 2:39 AM, Clifford Heath wrote: > On 09/02/17 16:36, rickman wrote: >> On 2/8/2017 7:19 PM, pcdhobbs@gmail.com wrote: >>>> That doesn't explain how the "herd" is controlled. >>> >>> It's mostly large-scale rotating machinery with a lot of inertia. When >>> the load exceeds the input, the 'herd' slows down. Thus you keep the >>> system in balance by watching the frequency. >> >> That's not the question I'm asking. > > Yes, it is, but you still don't seem to understand why. > >> You have 10,000 people on a ship as oarsmen. None can really see the >> others, but they all can hear each other and they all chant the cadence >> as they paddle. It is *much* more effective if they all stroke >> together. > > That's a terrible example that does not apply. > The oarsmen must stroke together only because the oars would > collide. Remove 2 of every three oars so there is room and > each oarsman could stroke at whatever pace he chose. He > could also choose how much actual work to do on each stroke > too (as can each one when all are in sync of course). > He can idle along, letting the passing water push the oar, > or he can lean into it, and propel the boat. > > In a similar way, each generator can keep pace, however much > power it is contributing. But if it contributes little power, > its turbine will tend to run fast, pushing its phase ahead, > which makes it contribute more power and so stay in a (slightly > advanced) phase lock. Similarly if it falls behind; its power > contribution falls until it's being dragged along by the grid, > instead if pushed along by its turbine (like the rower letting > the water push the oar). > > Each power station can in this way sense when all together are > meeting the demand, or when they need to change, and each can > change in the right direction on their own. Ok, thank you for the explanation. -- Rick C
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| From | Martin Brown <|||newspam|||@nezumi.demon.co.uk> |
|---|---|
| Date | 2017-02-09 09:46 +0000 |
| Message-ID | <o7hdp7$b6k$1@gioia.aioe.org> |
| In reply to | #446973 |
On 09/02/2017 05:36, rickman wrote: > On 2/8/2017 7:19 PM, pcdhobbs@gmail.com wrote: >>> That doesn't explain how the "herd" is controlled. >> >> It's mostly large-scale rotating machinery with a lot of inertia. When >> the load exceeds the input, the 'herd' slows down. Thus you keep the >> system in balance by watching the frequency. > > That's not the question I'm asking. But it is the answer to how does it all work together. An offline generator carefully syncs itself to the herd before joining the pack and once connected to the grid is locked to it by the sheer momentum of the mechanical energy in the turbines and the drag created by the load. Entrainment describes the tendency of oscillators at similar frequencies to lock step even when you don't want them to. > > You have 10,000 people on a ship as oarsmen. None can really see the > others, but they all can hear each other and they all chant the cadence > as they paddle. It is *much* more effective if they all stroke > together. There is no guy on deck with a drum, just the chorus of > voices crying, "stroke, stroke,..." > > The pilot can talk to any of the oarsmen singly. Or maybe he has an > intercom that lets him talk to them all. I don't know. > > If the pilot wants to speed up the boat, what does he do? Asks a few of the biggest or most responsive units to increase their output accordingly or to come onstream if they are really short of power. UK uses pumped storage to handle short term transient loads like soap opera advert breaks and half time at televised football matches. > > That's what I'm asking about keeping the grid on sync with the time. How > does the pilot control the oarsmen and how do the oarsmen keep in step > but also nudge the stroke? They can all monitor grid frequency and so know which way they are aiming for in a classic local control loop. But the ensemble average works much better than the regulation on any single unit. -- Regards, Martin Brown
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| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-02-09 05:03 -0500 |
| Message-ID | <o7hemi$9iq$1@dont-email.me> |
| In reply to | #446990 |
On 2/9/2017 4:46 AM, Martin Brown wrote: > On 09/02/2017 05:36, rickman wrote: >> On 2/8/2017 7:19 PM, pcdhobbs@gmail.com wrote: >>>> That doesn't explain how the "herd" is controlled. >>> >>> It's mostly large-scale rotating machinery with a lot of inertia. When >>> the load exceeds the input, the 'herd' slows down. Thus you keep the >>> system in balance by watching the frequency. >> >> That's not the question I'm asking. > > But it is the answer to how does it all work together. An offline > generator carefully syncs itself to the herd before joining the pack and > once connected to the grid is locked to it by the sheer momentum of the > mechanical energy in the turbines and the drag created by the load. > > Entrainment describes the tendency of oscillators at similar frequencies > to lock step even when you don't want them to. I'm not asking how they lock to each other. That I get. I'm asking how the herd is steered. I'm told in Europe they have a single measurement of the frequency or more likely the phase and once a day an order is sent out for all of the operators to change their speeds. But if they are all synced to each other, how do they change the speed? Each one is outputting some amount of energy which has to do with demand (which I also don't see how they know how much energy to create). Theoretically they are only producing the energy their customers are asking for and get billed for. >> You have 10,000 people on a ship as oarsmen. None can really see the >> others, but they all can hear each other and they all chant the cadence >> as they paddle. It is *much* more effective if they all stroke >> together. There is no guy on deck with a drum, just the chorus of >> voices crying, "stroke, stroke,..." >> >> The pilot can talk to any of the oarsmen singly. Or maybe he has an >> intercom that lets him talk to them all. I don't know. >> >> If the pilot wants to speed up the boat, what does he do? > > Asks a few of the biggest or most responsive units to increase their > output accordingly or to come onstream if they are really short of > power. UK uses pumped storage to handle short term transient loads like > soap opera advert breaks and half time at televised football matches. No one said they are short of power. Say the power is perfectly matched, but the phase has drifted behind. The power they generate needs to match the power being consumed by their customers, no? >> That's what I'm asking about keeping the grid on sync with the time. How >> does the pilot control the oarsmen and how do the oarsmen keep in step >> but also nudge the stroke? > > They can all monitor grid frequency and so know which way they are > aiming for in a classic local control loop. But the ensemble average > works much better than the regulation on any single unit. So everyone acts independently? -- Rick C
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| From | Jeroen Belleman <jeroen@nospam.please> |
|---|---|
| Date | 2017-02-09 11:45 +0100 |
| Message-ID | <o7hh7j$hhl$1@gioia.aioe.org> |
| In reply to | #446993 |
On 2017-02-09 11:03, rickman wrote: > On 2/9/2017 4:46 AM, Martin Brown wrote: >> On 09/02/2017 05:36, rickman wrote: >>> On 2/8/2017 7:19 PM, pcdhobbs@gmail.com wrote: >>>>> That doesn't explain how the "herd" is controlled. >>>> >>>> It's mostly large-scale rotating machinery with a lot of >>>> inertia. When the load exceeds the input, the 'herd' slows >>>> down. Thus you keep the system in balance by watching the >>>> frequency. >>> >>> That's not the question I'm asking. >> >> But it is the answer to how does it all work together. An offline >> generator carefully syncs itself to the herd before joining the >> pack and once connected to the grid is locked to it by the sheer >> momentum of the mechanical energy in the turbines and the drag >> created by the load. >> >> Entrainment describes the tendency of oscillators at similar >> frequencies to lock step even when you don't want them to. > > I'm not asking how they lock to each other. That I get. I'm asking > how the herd is steered. I'm told in Europe they have a single > measurement of the frequency or more likely the phase and once a day > an order is sent out for all of the operators to change their > speeds. > > But if they are all synced to each other, how do they change the > speed? Each one is outputting some amount of energy which has to do > with demand (which I also don't see how they know how much energy to > create). Theoretically they are only producing the energy their > customers are asking for and get billed for. They don't change speed. Individually, they can't. They have to stay synchronous. They change the power they inject into the network, according to the network frequency error. Collectively, that will steer the frequency to its set point. In Europe, the conversion factor is of the order of 20GW/Hz. Measuring frequency is easy enough that each plant can work out for itself which way to adjust its own power output. Only for long- term accuracy do they need some central authority. Get rid of the idea that demand is the primary input variable. It's not. The collective load is basically resistive. Jeroen Belleman
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| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-02-09 07:12 -0500 |
| Message-ID | <o7hm7t$51l$1@dont-email.me> |
| In reply to | #446995 |
On 2/9/2017 5:45 AM, Jeroen Belleman wrote: > On 2017-02-09 11:03, rickman wrote: >> On 2/9/2017 4:46 AM, Martin Brown wrote: >>> On 09/02/2017 05:36, rickman wrote: >>>> On 2/8/2017 7:19 PM, pcdhobbs@gmail.com wrote: >>>>>> That doesn't explain how the "herd" is controlled. >>>>> >>>>> It's mostly large-scale rotating machinery with a lot of >>>>> inertia. When the load exceeds the input, the 'herd' slows >>>>> down. Thus you keep the system in balance by watching the >>>>> frequency. >>>> >>>> That's not the question I'm asking. >>> >>> But it is the answer to how does it all work together. An offline >>> generator carefully syncs itself to the herd before joining the >>> pack and once connected to the grid is locked to it by the sheer >>> momentum of the mechanical energy in the turbines and the drag >>> created by the load. >>> >>> Entrainment describes the tendency of oscillators at similar >>> frequencies to lock step even when you don't want them to. >> >> I'm not asking how they lock to each other. That I get. I'm asking >> how the herd is steered. I'm told in Europe they have a single >> measurement of the frequency or more likely the phase and once a day >> an order is sent out for all of the operators to change their >> speeds. >> >> But if they are all synced to each other, how do they change the >> speed? Each one is outputting some amount of energy which has to do >> with demand (which I also don't see how they know how much energy to >> create). Theoretically they are only producing the energy their >> customers are asking for and get billed for. > > They don't change speed. Individually, they can't. I didn't say "change speed". I said "change the speed"... of the network! > They have to > stay synchronous. They change the power they inject into the network, > according to the network frequency error. Collectively, that will > steer the frequency to its set point. In Europe, the conversion factor > is of the order of 20GW/Hz. Yes, how is this controlled? > Measuring frequency is easy enough that each plant can work out > for itself which way to adjust its own power output. Only for long- > term accuracy do they need some central authority. Don't they sell power? If they are selling power to a customer and they have to pump extra power into the grid, who pays for it? > Get rid of the idea that demand is the primary input variable. It's > not. The collective load is basically resistive. Then how does it get billed? Money is the primary input variable. -- Rick C
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| From | Jeroen Belleman <jeroen@nospam.please> |
|---|---|
| Date | 2017-02-09 13:31 +0100 |
| Message-ID | <o7hnfq$s64$1@gioia.aioe.org> |
| In reply to | #446997 |
On 2017-02-09 13:12, rickman wrote: > On 2/9/2017 5:45 AM, Jeroen Belleman wrote: >> On 2017-02-09 11:03, rickman wrote: >>> On 2/9/2017 4:46 AM, Martin Brown wrote: >>>> On 09/02/2017 05:36, rickman wrote: >>>>> On 2/8/2017 7:19 PM, pcdhobbs@gmail.com wrote: >>>>>>> That doesn't explain how the "herd" is controlled. >>>>>> >>>>>> It's mostly large-scale rotating machinery with a lot of >>>>>> inertia. When the load exceeds the input, the 'herd' slows >>>>>> down. Thus you keep the system in balance by watching the >>>>>> frequency. >>>>> >>>>> That's not the question I'm asking. >>>> >>>> But it is the answer to how does it all work together. An offline >>>> generator carefully syncs itself to the herd before joining the >>>> pack and once connected to the grid is locked to it by the sheer >>>> momentum of the mechanical energy in the turbines and the drag >>>> created by the load. >>>> >>>> Entrainment describes the tendency of oscillators at similar >>>> frequencies to lock step even when you don't want them to. >>> >>> I'm not asking how they lock to each other. That I get. I'm asking >>> how the herd is steered. I'm told in Europe they have a single >>> measurement of the frequency or more likely the phase and once a day >>> an order is sent out for all of the operators to change their >>> speeds. >>> >>> But if they are all synced to each other, how do they change the >>> speed? Each one is outputting some amount of energy which has to do >>> with demand (which I also don't see how they know how much energy to >>> create). Theoretically they are only producing the energy their >>> customers are asking for and get billed for. >> >> They don't change speed. Individually, they can't. > > I didn't say "change speed". I said "change the speed"... of the network! Dammit! You're trawling for trouble! > >> They have to >> stay synchronous. They change the power they inject into the network, >> according to the network frequency error. Collectively, that will >> steer the frequency to its set point. In Europe, the conversion factor >> is of the order of 20GW/Hz. > > Yes, how is this controlled? As I said, if the frequency is low, the plant increases its power output. More steam into the turbine, adjust generator excitation to remain synchronous, power output goes up. > Don't they sell power? If they are selling power to a customer and they > have to pump extra power into the grid, who pays for it? The consumers, collectively. The power doesn't just vanish. It's distributed over all consumers. >> Get rid of the idea that demand is the primary input variable. It's >> not. The collective load is basically resistive. > > Then how does it get billed? Money is the primary input variable. That should be evident by now. Jeroen Belleman
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| From | Martin Brown <|||newspam|||@nezumi.demon.co.uk> |
|---|---|
| Date | 2017-02-09 12:14 +0000 |
| Message-ID | <o7hmf6$qef$1@gioia.aioe.org> |
| In reply to | #446993 |
On 09/02/2017 10:03, rickman wrote: > On 2/9/2017 4:46 AM, Martin Brown wrote: >> On 09/02/2017 05:36, rickman wrote: >>> On 2/8/2017 7:19 PM, pcdhobbs@gmail.com wrote: >>>>> That doesn't explain how the "herd" is controlled. >>>> >>>> It's mostly large-scale rotating machinery with a lot of inertia. When >>>> the load exceeds the input, the 'herd' slows down. Thus you keep the >>>> system in balance by watching the frequency. >>> >>> That's not the question I'm asking. >> >> But it is the answer to how does it all work together. An offline >> generator carefully syncs itself to the herd before joining the pack and >> once connected to the grid is locked to it by the sheer momentum of the >> mechanical energy in the turbines and the drag created by the load. >> >> Entrainment describes the tendency of oscillators at similar frequencies >> to lock step even when you don't want them to. > > I'm not asking how they lock to each other. That I get. I'm asking how > the herd is steered. I'm told in Europe they have a single measurement > of the frequency or more likely the phase and once a day an order is > sent out for all of the operators to change their speeds. OK. In familiar control terms there is a local proportional to error control loop on each generator that tries to maintain frequency and in addition there is an integral control loop over 24 hours that tries to maintain the running average equal to nominal cycles/day too. The latter is the one done supra nationally by asking a few of the most powerful stations to up their output slightly at night. > > But if they are all synced to each other, how do they change the speed? > Each one is outputting some amount of energy which has to do with demand > (which I also don't see how they know how much energy to create). > Theoretically they are only producing the energy their customers are > asking for and get billed for. If the torque applied by the mechanical drive system exceeds the drag presented by the load the whole system spins up very slightly. The ones now outputting extra power making life easier for the others. >>> You have 10,000 people on a ship as oarsmen. None can really see the >>> others, but they all can hear each other and they all chant the cadence >>> as they paddle. It is *much* more effective if they all stroke >>> together. There is no guy on deck with a drum, just the chorus of >>> voices crying, "stroke, stroke,..." >>> >>> The pilot can talk to any of the oarsmen singly. Or maybe he has an >>> intercom that lets him talk to them all. I don't know. >>> >>> If the pilot wants to speed up the boat, what does he do? >> >> Asks a few of the biggest or most responsive units to increase their >> output accordingly or to come onstream if they are really short of >> power. UK uses pumped storage to handle short term transient loads like >> soap opera advert breaks and half time at televised football matches. > > No one said they are short of power. Say the power is perfectly > matched, but the phase has drifted behind. The power they generate > needs to match the power being consumed by their customers, no? The phase is irrelevant apart from when you are connecting a new power station into the grid when it needs to be matched up first. Once connected up its speed it regulated by the whole ensemble and daily corrections are done by cycle counting and an integral control loop. It is a dynamic system where the instantaneous load is never quite matched to the demand which is why the frequency is allowed to vary. It would be too costly to try and hold it to a tighter tolerance. >>> That's what I'm asking about keeping the grid on sync with the time. How >>> does the pilot control the oarsmen and how do the oarsmen keep in step >>> but also nudge the stroke? >> >> They can all monitor grid frequency and so know which way they are >> aiming for in a classic local control loop. But the ensemble average >> works much better than the regulation on any single unit. > > So everyone acts independently? The first order control is eliminate proportional error from the target frequency but that is never achieved in practice. So the next level correction is based on the integral number of cycles in 24 hours (which can also be measured and determined locally but ISTR is for historical reasons is done centrally by CEGB in the UK). They have a much better understanding of the national and international predicted load profile than any one generating plant can possibly have. -- Regards, Martin Brown
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| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-02-09 07:25 -0500 |
| Message-ID | <o7hn01$auq$1@dont-email.me> |
| In reply to | #446998 |
On 2/9/2017 7:14 AM, Martin Brown wrote: > On 09/02/2017 10:03, rickman wrote: >> On 2/9/2017 4:46 AM, Martin Brown wrote: >>> On 09/02/2017 05:36, rickman wrote: >>>> On 2/8/2017 7:19 PM, pcdhobbs@gmail.com wrote: >>>>>> That doesn't explain how the "herd" is controlled. >>>>> >>>>> It's mostly large-scale rotating machinery with a lot of inertia. When >>>>> the load exceeds the input, the 'herd' slows down. Thus you keep the >>>>> system in balance by watching the frequency. >>>> >>>> That's not the question I'm asking. >>> >>> But it is the answer to how does it all work together. An offline >>> generator carefully syncs itself to the herd before joining the pack and >>> once connected to the grid is locked to it by the sheer momentum of the >>> mechanical energy in the turbines and the drag created by the load. >>> >>> Entrainment describes the tendency of oscillators at similar frequencies >>> to lock step even when you don't want them to. >> >> I'm not asking how they lock to each other. That I get. I'm asking how >> the herd is steered. I'm told in Europe they have a single measurement >> of the frequency or more likely the phase and once a day an order is >> sent out for all of the operators to change their speeds. > > OK. In familiar control terms there is a local proportional to error > control loop on each generator that tries to maintain frequency and in > addition there is an integral control loop over 24 hours that tries to > maintain the running average equal to nominal cycles/day too. > > The latter is the one done supra nationally by asking a few of the most > powerful stations to up their output slightly at night. >> >> But if they are all synced to each other, how do they change the speed? >> Each one is outputting some amount of energy which has to do with demand >> (which I also don't see how they know how much energy to create). >> Theoretically they are only producing the energy their customers are >> asking for and get billed for. > > If the torque applied by the mechanical drive system exceeds the drag > presented by the load the whole system spins up very slightly. The ones > now outputting extra power making life easier for the others. > >>>> You have 10,000 people on a ship as oarsmen. None can really see the >>>> others, but they all can hear each other and they all chant the cadence >>>> as they paddle. It is *much* more effective if they all stroke >>>> together. There is no guy on deck with a drum, just the chorus of >>>> voices crying, "stroke, stroke,..." >>>> >>>> The pilot can talk to any of the oarsmen singly. Or maybe he has an >>>> intercom that lets him talk to them all. I don't know. >>>> >>>> If the pilot wants to speed up the boat, what does he do? >>> >>> Asks a few of the biggest or most responsive units to increase their >>> output accordingly or to come onstream if they are really short of >>> power. UK uses pumped storage to handle short term transient loads like >>> soap opera advert breaks and half time at televised football matches. >> >> No one said they are short of power. Say the power is perfectly >> matched, but the phase has drifted behind. The power they generate >> needs to match the power being consumed by their customers, no? > > The phase is irrelevant apart from when you are connecting a new power > station into the grid when it needs to be matched up first. Once > connected up its speed it regulated by the whole ensemble and daily > corrections are done by cycle counting and an integral control loop. This conversation gets old when people don't understand the basics. The phase is what controls the time on the clocks. That is the thing that gets adjusted over the course of the day/week/month to keep the clocks running on time. > It is a dynamic system where the instantaneous load is never quite > matched to the demand which is why the frequency is allowed to vary. It > would be too costly to try and hold it to a tighter tolerance. > >>>> That's what I'm asking about keeping the grid on sync with the time. >>>> How >>>> does the pilot control the oarsmen and how do the oarsmen keep in step >>>> but also nudge the stroke? >>> >>> They can all monitor grid frequency and so know which way they are >>> aiming for in a classic local control loop. But the ensemble average >>> works much better than the regulation on any single unit. >> >> So everyone acts independently? > > The first order control is eliminate proportional error from the target > frequency but that is never achieved in practice. So the next level > correction is based on the integral number of cycles in 24 hours (which > can also be measured and determined locally but ISTR is for historical > reasons is done centrally by CEGB in the UK). They have a much better > understanding of the national and international predicted load profile > than any one generating plant can possibly have. The grid is nudged by power generators outputting more power than "something". I don't know what the "something" is. Meanwhile each generator is charging a customer somewhere and they can only bill them for what they are using. So how can a power plant output more power than they are billing and still make profit? -- Rick C
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| From | Martin Brown <|||newspam|||@nezumi.demon.co.uk> |
|---|---|
| Date | 2017-02-10 09:17 +0000 |
| Message-ID | <o7k0fd$cnd$1@gioia.aioe.org> |
| In reply to | #447000 |
On 09/02/2017 12:25, rickman wrote: > On 2/9/2017 7:14 AM, Martin Brown wrote: >> On 09/02/2017 10:03, rickman wrote: >>> On 2/9/2017 4:46 AM, Martin Brown wrote: >>>> On 09/02/2017 05:36, rickman wrote: >>>>> On 2/8/2017 7:19 PM, pcdhobbs@gmail.com wrote: >>>>>>> That doesn't explain how the "herd" is controlled. >>>>>> >>>>>> It's mostly large-scale rotating machinery with a lot of inertia. >>>>>> When >>>>>> the load exceeds the input, the 'herd' slows down. Thus you keep the >>>>>> system in balance by watching the frequency. >>>>> >>>>> That's not the question I'm asking. >>>> >>>> But it is the answer to how does it all work together. An offline >>>> generator carefully syncs itself to the herd before joining the pack >>>> and >>>> once connected to the grid is locked to it by the sheer momentum of the >>>> mechanical energy in the turbines and the drag created by the load. >>>> >>>> Entrainment describes the tendency of oscillators at similar >>>> frequencies >>>> to lock step even when you don't want them to. >>> >>> I'm not asking how they lock to each other. That I get. I'm asking how >>> the herd is steered. I'm told in Europe they have a single measurement >>> of the frequency or more likely the phase and once a day an order is >>> sent out for all of the operators to change their speeds. >> >> OK. In familiar control terms there is a local proportional to error >> control loop on each generator that tries to maintain frequency and in >> addition there is an integral control loop over 24 hours that tries to >> maintain the running average equal to nominal cycles/day too. >> >> The latter is the one done supra nationally by asking a few of the most >> powerful stations to up their output slightly at night. >>> >>> But if they are all synced to each other, how do they change the speed? >>> Each one is outputting some amount of energy which has to do with demand >>> (which I also don't see how they know how much energy to create). >>> Theoretically they are only producing the energy their customers are >>> asking for and get billed for. >> >> If the torque applied by the mechanical drive system exceeds the drag >> presented by the load the whole system spins up very slightly. The ones >> now outputting extra power making life easier for the others. >> >>>>> You have 10,000 people on a ship as oarsmen. None can really see the >>>>> others, but they all can hear each other and they all chant the >>>>> cadence >>>>> as they paddle. It is *much* more effective if they all stroke >>>>> together. There is no guy on deck with a drum, just the chorus of >>>>> voices crying, "stroke, stroke,..." >>>>> >>>>> The pilot can talk to any of the oarsmen singly. Or maybe he has an >>>>> intercom that lets him talk to them all. I don't know. >>>>> >>>>> If the pilot wants to speed up the boat, what does he do? >>>> >>>> Asks a few of the biggest or most responsive units to increase their >>>> output accordingly or to come onstream if they are really short of >>>> power. UK uses pumped storage to handle short term transient loads like >>>> soap opera advert breaks and half time at televised football matches. >>> >>> No one said they are short of power. Say the power is perfectly >>> matched, but the phase has drifted behind. The power they generate >>> needs to match the power being consumed by their customers, no? >> >> The phase is irrelevant apart from when you are connecting a new power >> station into the grid when it needs to be matched up first. Once >> connected up its speed it regulated by the whole ensemble and daily >> corrections are done by cycle counting and an integral control loop. > > This conversation gets old when people don't understand the basics. And that is *YOU*. The phase is drifting out by more 2pi every thousand cycles when the frequency is just 0.1Hz off its nominal value (a common situation). Just about all clocks work by dividing down some form of oscillator signal and rely on counting the *cycles* of that signal. The phase error merely represents sub cycle jitter on that timing resolution - which may be important in some time critical applications like interferometry or ultra precision timekeeping for GPS. > The > phase is what controls the time on the clocks. That is the thing that > gets adjusted over the course of the day/week/month to keep the clocks > running on time. No it isn't. YOU have failed to understand the basics. It is the average frequency that is kept tightly constrained over a 24 hour period and kept even more accurate over the longer term. >> It is a dynamic system where the instantaneous load is never quite >> matched to the demand which is why the frequency is allowed to vary. It >> would be too costly to try and hold it to a tighter tolerance. >> >>>>> That's what I'm asking about keeping the grid on sync with the time. >>>>> How >>>>> does the pilot control the oarsmen and how do the oarsmen keep in step >>>>> but also nudge the stroke? >>>> >>>> They can all monitor grid frequency and so know which way they are >>>> aiming for in a classic local control loop. But the ensemble average >>>> works much better than the regulation on any single unit. >>> >>> So everyone acts independently? >> >> The first order control is eliminate proportional error from the target >> frequency but that is never achieved in practice. So the next level >> correction is based on the integral number of cycles in 24 hours (which >> can also be measured and determined locally but ISTR is for historical >> reasons is done centrally by CEGB in the UK). They have a much better >> understanding of the national and international predicted load profile >> than any one generating plant can possibly have. > > The grid is nudged by power generators outputting more power than > "something". I don't know what the "something" is. Meanwhile each > generator is charging a customer somewhere and they can only bill them > for what they are using. So how can a power plant output more power > than they are billing and still make profit? The "something" is the load on the other end. Energy is conserved so the extra torque they input results in spinning up the generators. Equivalently they can ask some of the biggest sink loads to drop off and exactly the same would happen. I begin to think you are either extremely stupid or are deliberately trolling. -- Regards, Martin Brown
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