• Grid Stability and Renewable Power

    From Ricky@21:1/5 to All on Sun Apr 17 20:01:23 2022
    Is there some fundamental reason why renewable power sources on the grid can't provide the equivalent of "inertia", to stabilize the grid?

    It seems to me the only issue is normally renewable power sources are optimized to provide the maximum power possible, so if the grid frequency slows (because there is less power sourced than the power drained), renewable power generation is already
    maxed out.

    So would operating at a few percent below optimum provide adequate energy margin to act to stabilize the grid? If the frequency drops, the renewable power sources pull in efficiency a bit to pump more energy into the grid and bring back up the frequency.
    If the grid frequency drops, the renewable power sources drop back on the efficiency a small bit and the lower output again stabilizes the grid.

    Is this not adequate in some way? Is operating a couple of percent off optimum not acceptable? Does anyone actually know the answer rather than speculating?

    Of course, this won't eliminate the need for grid storage for intermittent power sources. But it would solve the problem of short term grid stability with renewable energy sources.

    Someone is trying to tell me that using inverters makes it impossible to use them for grid stability, which makes no sense to me. Then again, I believe people here have shown that wind turbines don't use inverters. AC is generated directly in the
    generator without inverters.

    --

    Rick C.

    - Get 1,000 miles of free Supercharging
    - Tesla referral code - https://ts.la/richard11209

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Anthony William Sloman@21:1/5 to Ricky on Sun Apr 17 20:34:39 2022
    On Monday, April 18, 2022 at 1:01:27 PM UTC+10, Ricky wrote:
    Is there some fundamental reason why renewable power sources on the grid can't provide the equivalent of "inertia", to stabilize the grid?

    No. Grid storage power storage provides exactly that. Pumped hydroelectric power is the traditional scheme but grid-scale batteries are faster.

    Australian rooftop solar installation are starting to include enough battery storage to keep the house running overnight. The local electric utilities aren't enthusiastic about buying surplus electric power from rooftop installations during the day, so
    it's more profitable for the house-holder to spend of the order of $1,000 on a battery and use up the excess power themselves.

    It seems to me the only issue is normally renewable power sources are optimized to provide the maximum power possible, so if the grid frequency slows (because there is less power sourced than the power drained), renewable power generation is already
    maxed out.

    If you have grid-scale batteries the frequency doesn't change much at all - they can provide cycle-to-cycle phase correction.

    Half the capacity of South Australia's famous Tesla grid-scale batter is devoted to doing just that, and it paid off the price of the whole battery within two years.

    https://en.wikipedia.org/wiki/Hornsdale_Power_Reserve

    So would operating at a few percent below optimum provide adequate energy margin to act to stabilize the grid?

    Not really. The sun goes down at night. Wind turbines are even less predictable.

    If the frequency drops, the renewable power sources pull in efficiency a bit to pump more energy into the grid and bring back up the frequency. If the grid frequency drops, the renewable power sources drop back on the efficiency a small bit and the
    lower output again stabilizes the grid.

    Is this not adequate in some way? Is operating a couple of percent off optimum not acceptable? Does anyone actually know the answer rather than speculating?

    It's not what they are doing in South Australia

    Of course, this won't eliminate the need for grid storage for intermittent power sources. But it would solve the problem of short term grid stability with renewable energy sources.

    It's a sub-optimal solution.

    Someone is trying to tell me that using inverters makes it impossible to use them for grid stability, which makes no sense to me.

    The South Australian story makes it obvious that this is nonsense.

    Then again, I believe people here have shown that wind turbines don't use inverters. AC is generated directly in the generator without inverters.

    But not at the right frequency. Inverters are ubiquitous.

    --
    Bill Sloman, Sydney

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Klaus Kragelund@21:1/5 to Ricky on Mon Apr 18 09:34:18 2022
    18.04.22 06:01, Ricky wrote:
    Is there some fundamental reason why renewable power sources on the grid can't provide the equivalent of "inertia", to stabilize the grid?

    It seems to me the only issue is normally renewable power sources are optimized to provide the maximum power possible, so if the grid frequency slows (because there is less power sourced than the power drained), renewable power generation is already
    maxed out.

    So would operating at a few percent below optimum provide adequate energy margin to act to stabilize the grid? If the frequency drops, the renewable power sources pull in efficiency a bit to pump more energy into the grid and bring back up the
    frequency. If the grid frequency drops, the renewable power sources drop back on the efficiency a small bit and the lower output again stabilizes the grid.

    Is this not adequate in some way? Is operating a couple of percent off optimum not acceptable? Does anyone actually know the answer rather than speculating?

    Of course, this won't eliminate the need for grid storage for intermittent power sources. But it would solve the problem of short term grid stability with renewable energy sources.

    Someone is trying to tell me that using inverters makes it impossible to use them for grid stability, which makes no sense to me. Then again, I believe people here have shown that wind turbines don't use inverters. AC is generated directly in the
    generator without inverters.


    Older systems with high percentage of old style synchronized high inertia generators provided good stability

    In the future more generated power will be decentralized, so you need a distributed communication channel to set the duty point of the majority of the power generated

    AFAIK most solar systems are current sources with no knowledge of grid state, resulting in VAR squishing around on the grid


    --
    Klaus

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Anthony William Sloman@21:1/5 to Klaus Kragelund on Sun Apr 17 23:59:35 2022
    On Monday, April 18, 2022 at 4:34:25 PM UTC+10, Klaus Kragelund wrote:
    18.04.22 06:01, Ricky wrote:
    Is there some fundamental reason why renewable power sources on the grid can't provide the equivalent of "inertia", to stabilize the grid?

    It seems to me the only issue is normally renewable power sources are optimized to provide the maximum power possible, so if the grid frequency slows (because there is less power sourced than the power drained), renewable power generation is already
    maxed out.

    So would operating at a few percent below optimum provide adequate energy margin to act to stabilize the grid? If the frequency drops, the renewable power sources pull in efficiency a bit to pump more energy into the grid and bring back up the
    frequency. If the grid frequency drops, the renewable power sources drop back on the efficiency a small bit and the lower output again stabilizes the grid.

    Is this not adequate in some way? Is operating a couple of percent off optimum not acceptable? Does anyone actually know the answer rather than speculating?

    Of course, this won't eliminate the need for grid storage for intermittent power sources. But it would solve the problem of short term grid stability with renewable energy sources.

    Someone is trying to tell me that using inverters makes it impossible to use them for grid stability, which makes no sense to me. Then again, I believe people here have shown that wind turbines don't use inverters. AC is generated directly in the
    generator without inverters.

    Older systems with high percentage of old style synchronized high inertia generators provided good stability

    In the future more generated power will be decentralized, so you need a distributed communication channel to set the duty point of the majority of the power generated

    AFAIK most solar systems are current sources with no knowledge of grid state, resulting in VAR squishing around on the grid.

    The people who turn that low voltage direct current output into mains frequency input into the grid are responsible for getting the phase right.

    If the utilities don't manage them well enough to prevent "VAR squishing around the grid" that's simple incompetence.

    --
    Bill Sloman, Sydney

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Allison@21:1/5 to Ricky on Mon Apr 18 00:17:12 2022
    Ricky wrote:
    ==========

    Is there some fundamental reason why renewable power sources on the grid can't provide the equivalent of "inertia", to stabilize the grid?


    ** They do that right now and for the past 100 years.

    Hydro power stations are the main frequency regulating elements in a grid. Certainly here on the east cost of Australia ( Snowy River Scheme) and I bet in any other place blessed with hydro.

    Reasons being that generation can be fine controlled almost instantly in response to frequency deviations and permanently availability when a number of dams and stations are involved.

    The permanently part arises form the ability pump water up hill and keep a few dams full at all times.
    Sun light and wind are God's domain, not human controlled.



    ...... Phil

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From whit3rd@21:1/5 to Ricky on Mon Apr 18 00:51:00 2022
    On Sunday, April 17, 2022 at 8:01:27 PM UTC-7, Ricky wrote:
    Is there some fundamental reason why renewable power sources on the grid can't provide the equivalent of "inertia", to stabilize the grid?

    What is the 'inertia' analogy, exactly? Most renewable power sources aren't like hydroelectric, with large
    stored reserves and quick access to extra generating capacity, but a 'grid' can have (and use) a variety of
    sources, including some with stored reserves, in cooperative fashion.

    It's a stable grid if its management has the right combination of feedback and time delays... just like
    a compensated op amp.

    [about solar photovoltaics]
    Someone is trying to tell me that using inverters makes it impossible to use them for grid stability, which makes no sense to me.

    If by that they mean inverters that aren't managed as part of the overall grid, but which are always-full-power,
    then the feedback requirement isn't met. So it does make some sense. The photovoltaic output would have
    to exceed the sum of easily-controlled other sources, or have abrupt transitions that exceed slew rate
    of the grid-control options. Or, the grid control would have to be badly designed.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to whit3rd@gmail.com on Mon Apr 18 08:59:31 2022
    On a sunny day (Mon, 18 Apr 2022 00:51:00 -0700 (PDT)) it happened whit3rd <whit3rd@gmail.com> wrote in <eabbe49a-d070-4224-b10f-629921a15f5fn@googlegroups.com>:

    On Sunday, April 17, 2022 at 8:01:27 PM UTC-7, Ricky wrote:
    Is there some fundamental reason why renewable power sources on the grid can't provide the equivalent of "inertia", to
    stabilize the grid?

    What is the 'inertia' analogy, exactly? Most renewable power sources aren't like hydroelectric, with large
    stored reserves and quick access to extra generating capacity, but a 'grid' can have (and use) a variety of
    sources, including some with stored reserves, in cooperative fashion.

    It's a stable grid if its management has the right combination of feedback and time delays... just like
    a compensated op amp.

    [about solar photovoltaics]
    Someone is trying to tell me that using inverters makes it impossible to use them for grid stability, which makes no sense to
    me.

    If by that they mean inverters that aren't managed as part of the overall grid, but which are always-full-power,
    then the feedback requirement isn't met. So it does make some sense. The photovoltaic output would have
    to exceed the sum of easily-controlled other sources, or have abrupt transitions that exceed slew rate
    of the grid-control options. Or, the grid control would have to be badly designed.

    Molten salt sun power plants use 'inertia' to supply power day and night:
    https://www.yara.com/chemical-and-environmental-solutions/solar-power-molten-salt/

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Martin Brown@21:1/5 to Ricky on Mon Apr 18 10:45:24 2022
    On 18/04/2022 04:01, Ricky wrote:
    Is there some fundamental reason why renewable power sources on the
    grid can't provide the equivalent of "inertia", to stabilize the
    grid?

    Part of the problem in the UK was that because of micro generation on individual home roofs have to self protect their 4kW rated kit if the
    load gets too far off specification they each make an independent
    decision to disconnect leading to a runaway cascade failure.

    That is part of what the technical investigation into the big UK
    powercut that took down most of London and the SE in August 2019.

    The other snag was that the low frequency demand disconnect system
    dropped both load and active generation capacity on home roofs so that
    the numbers no longer added up. Net load shed was much less than the
    absolute load shed (because of local PV generation on roofs).

    https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/836626/20191003_E3C_Interim_Report_into_GB_Power_Disruption.pdf

    It is a case study in how adding renewables to the mix effectively
    destabilised the network because some of the new protections on big
    offshore windfarms were untested/incorrect and conceptually flawed.

    It seems to me the only issue is normally renewable power sources are optimized to provide the maximum power possible, so if the grid
    frequency slows (because there is less power sourced than the power
    drained), renewable power generation is already maxed out.

    The grid is generally balanced by dumping all residual power into
    electrolytic aluminium or brine plants that can absorb any amount of
    energy and can change how much they take in an instant. They do require
    a certain amount of power to stay hot/warm but can vary their
    consumption by two or possibly three orders of magnitude when required.

    So would operating at a few percent below optimum provide adequate
    energy margin to act to stabilize the grid? If the frequency drops,
    the renewable power sources pull in efficiency a bit to pump more
    energy into the grid and bring back up the frequency. If the grid
    frequency drops, the renewable power sources drop back on the
    efficiency a small bit and the lower output again stabilizes the
    grid.

    No. The individual domestic systems will each try to save themselves
    when the network conditions become adverse. Only really big generators
    can provide the inertia (pumped storage or solid state huge batteries)

    Neither can provide a long term solution so if some more conventional
    power doesn't come back onstream before it runs out you are stuck.

    The ultimate sanction is that the grid will shed great chunks of load
    until it is able to get the frequency back under control. The
    calculation of how much has been greatly complicated by solar PV.

    Is this not adequate in some way? Is operating a couple of percent
    off optimum not acceptable? Does anyone actually know the answer
    rather than speculating?

    There is no point in operating at anything other than peak efficiency.
    The grid is always balanced for consumption and generation with the
    loads of last resort taking up any instantaneous slack. They also get
    dumped off first if there is a glitch.

    Of course, this won't eliminate the need for grid storage for
    intermittent power sources. But it would solve the problem of short
    term grid stability with renewable energy sources.

    How? Each of the toy systems on a home will make its own decision about
    when to drop off as the frequency goes out of spec. You probably could
    allow them some more leeway to stay on grid for longer.

    Nothing can really get around the fact that if the house they are on
    gets disconnected from the grid by load shedding their contribution
    (which during daytime might well be net positive) is lost.

    The calculation that wasn't allowed for in the UK is that with domestic generation on home roofs and on a sunny day when you shed "load" you
    will also shed a whole bunch of local solar PV generation as well.

    --
    Regards,
    Martin Brown

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Glen Walpert@21:1/5 to Ricky on Mon Apr 18 12:44:00 2022
    On Sun, 17 Apr 2022 20:01:23 -0700 (PDT), Ricky wrote:

    Is there some fundamental reason why renewable power sources on the grid can't provide the equivalent of "inertia", to stabilize the grid?

    It seems to me the only issue is normally renewable power sources are optimized to provide the maximum power possible, so if the grid
    frequency slows (because there is less power sourced than the power
    drained), renewable power generation is already maxed out.

    So would operating at a few percent below optimum provide adequate
    energy margin to act to stabilize the grid? If the frequency drops, the renewable power sources pull in efficiency a bit to pump more energy
    into the grid and bring back up the frequency. If the grid frequency
    drops, the renewable power sources drop back on the efficiency a small
    bit and the lower output again stabilizes the grid.

    Is this not adequate in some way? Is operating a couple of percent off optimum not acceptable? Does anyone actually know the answer rather
    than speculating?

    Of course, this won't eliminate the need for grid storage for
    intermittent power sources. But it would solve the problem of short
    term grid stability with renewable energy sources.

    Someone is trying to tell me that using inverters makes it impossible to
    use them for grid stability, which makes no sense to me. Then again, I believe people here have shown that wind turbines don't use inverters.
    AC is generated directly in the generator without inverters.

    This is an active area of R&D, and there have been some pretty
    significant developments which seem to have gone by unnoticed by most,
    namely code changes mandating the use of inverters compliant with UL1741
    SA. This changed the requirements for grid connected inverters from a
    very simple "disconnect immediately when the grid goes out of a very
    narrow definition of normal and reconnect after the grid has been normal
    for 5 minutes" requirement ("Grid Interactive"), to a much more
    sophisticated "Grid Support" requirement, where inverters are required to
    help stabilize the grid. They can do this more effectively than large
    rotating generators because their response time is /much/ faster.

    UL1741 SA (Supplement A) has since been rolled into Rev 1 of the base
    UL1741 spec, but SA is still a good search term. The only accurate
    description of these requirements I have found, short of shelling out
    thousands on specs, is a one hour seminar available on the UL web site, registration required. There is a lot of BS on all other sources I have
    seen, mostly people don't seem to understand the relationship between
    reactive power and grid voltage (Grid Support inverters supply reactive
    power to the grid to help correct under voltage even if they are already
    at maximum output; they can deliver significant reactive power with only
    a small reduction in real power, and reactive power is more effective in boosting grid voltage than real power due to the characteristics of the rotating generators and motors on the grid. (By convention capacitors
    supply reactive power and inductive loads use it.)

    Requirements for grid connection of any power source are published in a utilities SRD (Source Requirements Document), and as far as I know all US utilities SRDs have required Grid Support inverters since 2020, and they
    are also required by the current NEC.

    Some utilities, Hawaii and possibly others, also reserve the right to
    require a SCADA-like monitoring and control network connection to your
    inverter - they want your knobs :-).

    There have been similar code changes in Canada and the EU.

    IEEE refers to grid connected inverters as "static synchronous
    generators" and the old-fashioned type as "rotary synchronous generators"
    in newer specs, liberally referenced by UL.

    Glen

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Ricky@21:1/5 to Martin Brown on Mon Apr 18 07:43:19 2022
    On Monday, April 18, 2022 at 5:45:31 AM UTC-4, Martin Brown wrote:
    On 18/04/2022 04:01, Ricky wrote:
    Is there some fundamental reason why renewable power sources on the
    grid can't provide the equivalent of "inertia", to stabilize the
    grid?
    Part of the problem in the UK was that because of micro generation on individual home roofs have to self protect their 4kW rated kit if the
    load gets too far off specification they each make an independent
    decision to disconnect leading to a runaway cascade failure.

    That is part of what the technical investigation into the big UK
    powercut that took down most of London and the SE in August 2019.

    The other snag was that the low frequency demand disconnect system
    dropped both load and active generation capacity on home roofs so that
    the numbers no longer added up. Net load shed was much less than the absolute load shed (because of local PV generation on roofs).

    https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/836626/20191003_E3C_Interim_Report_into_GB_Power_Disruption.pdf

    It is a case study in how adding renewables to the mix effectively destabilised the network because some of the new protections on big
    offshore windfarms were untested/incorrect and conceptually flawed.

    It seems to me the only issue is normally renewable power sources are optimized to provide the maximum power possible, so if the grid
    frequency slows (because there is less power sourced than the power drained), renewable power generation is already maxed out.
    The grid is generally balanced by dumping all residual power into electrolytic aluminium or brine plants that can absorb any amount of
    energy and can change how much they take in an instant. They do require
    a certain amount of power to stay hot/warm but can vary their
    consumption by two or possibly three orders of magnitude when required.

    So would operating at a few percent below optimum provide adequate
    energy margin to act to stabilize the grid? If the frequency drops,
    the renewable power sources pull in efficiency a bit to pump more
    energy into the grid and bring back up the frequency. If the grid frequency drops, the renewable power sources drop back on the
    efficiency a small bit and the lower output again stabilizes the
    grid.
    No. The individual domestic systems will each try to save themselves
    when the network conditions become adverse. Only really big generators
    can provide the inertia (pumped storage or solid state huge batteries)

    Neither can provide a long term solution so if some more conventional
    power doesn't come back onstream before it runs out you are stuck.

    The ultimate sanction is that the grid will shed great chunks of load
    until it is able to get the frequency back under control. The
    calculation of how much has been greatly complicated by solar PV.
    Is this not adequate in some way? Is operating a couple of percent
    off optimum not acceptable? Does anyone actually know the answer
    rather than speculating?
    There is no point in operating at anything other than peak efficiency.
    The grid is always balanced for consumption and generation with the
    loads of last resort taking up any instantaneous slack. They also get
    dumped off first if there is a glitch.
    Of course, this won't eliminate the need for grid storage for
    intermittent power sources. But it would solve the problem of short
    term grid stability with renewable energy sources.
    How? Each of the toy systems on a home will make its own decision about
    when to drop off as the frequency goes out of spec. You probably could
    allow them some more leeway to stay on grid for longer.

    Nothing can really get around the fact that if the house they are on
    gets disconnected from the grid by load shedding their contribution
    (which during daytime might well be net positive) is lost.

    The calculation that wasn't allowed for in the UK is that with domestic generation on home roofs and on a sunny day when you shed "load" you
    will also shed a whole bunch of local solar PV generation as well.

    Let's leave the small, domestic systems out of the conversation. The particular point someone was making was that no inverters used with wind power (or solar farms) has the ability to help stabilize the grid, because there is no rotating inertia. It
    was not claimed that this was not possible, but it was implied by pointing out no one had done this yet and it would be a very useful feature.

    Seems to me it would require some way of increasing the power output, which means the facility has to run below optimal efficiency to have anything in reserve.

    The advantage of natural inertia, is the continuous nature. As much energy as is needed is available if you are able to tolerate the reduction in frequency. Of course, there is a limit to the inertia available, but it seems to do the job pretty well in
    most cases, while currently we seem to get nothing from solar and wind power facilities.

    --

    Rick C.

    -- Get 1,000 miles of free Supercharging
    -- Tesla referral code - https://ts.la/richard11209

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Ricky@21:1/5 to palli...@gmail.com on Mon Apr 18 07:34:08 2022
    On Monday, April 18, 2022 at 3:17:17 AM UTC-4, palli...@gmail.com wrote:
    Ricky wrote:
    ==========

    Is there some fundamental reason why renewable power sources on the grid can't provide the equivalent of "inertia", to stabilize the grid?

    ** They do that right now and for the past 100 years.

    Hydro power stations are the main frequency regulating elements in a grid. Certainly here on the east cost of Australia ( Snowy River Scheme) and I bet in any other place blessed with hydro.

    Reasons being that generation can be fine controlled almost instantly in response to frequency deviations and permanently availability when a number of dams and stations are involved.

    The permanently part arises form the ability pump water up hill and keep a few dams full at all times.
    Sun light and wind are God's domain, not human controlled.

    OTHER than hydro... of course.

    --

    Rick C.

    + Get 1,000 miles of free Supercharging
    + Tesla referral code - https://ts.la/richard11209

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Allison@21:1/5 to Ricky on Mon Apr 18 14:51:38 2022
    Ricky wrote:
    ===========

    Is there some fundamental reason why renewable power sources on the grid can't
    provide the equivalent of "inertia", to stabilize the grid?

    It seems to me the only issue is normally renewable power sources are optimized to
    provide the maximum power possible, so if the grid frequency slows (because there
    is less power sourced than the power drained), renewable power generation is already maxed out.

    ** What happens now is that inverters feeding the grid *track* the existing frequency - cos they are minor players in supplying the load.
    But what if that were not the case, they became the majority suppliers and and instead were locked to a central clock ?

    Rotating machines would then follow them.



    ...... Phil

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Ricky@21:1/5 to palli...@gmail.com on Mon Apr 18 15:37:02 2022
    On Monday, April 18, 2022 at 5:51:42 PM UTC-4, palli...@gmail.com wrote:
    Ricky wrote:
    ===========

    Is there some fundamental reason why renewable power sources on the grid can't
    provide the equivalent of "inertia", to stabilize the grid?

    It seems to me the only issue is normally renewable power sources are optimized to
    provide the maximum power possible, so if the grid frequency slows (because there
    is less power sourced than the power drained), renewable power generation is already maxed out.
    ** What happens now is that inverters feeding the grid *track* the existing frequency - cos they are minor players in supplying the load.
    But what if that were not the case, they became the majority suppliers and and instead were locked to a central clock ?

    Rotating machines would then follow them.

    That's a weird thing to say. If the "inverters" were locked to a central clock and driving the grid, rotating generators would be no different than they are now, following the grid.

    The grid is very complex. Many different actors, who is leading and who is following in this dance? It's not quite so simple. That's why rotational inertia is useful.

    --

    Rick C.

    -+ Get 1,000 miles of free Supercharging
    -+ Tesla referral code - https://ts.la/richard11209

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Allison@21:1/5 to Ricky the IDIOT on Mon Apr 18 17:07:54 2022
    Ricky the IDIOT wrote:
    ==================

    Is there some fundamental reason why renewable power sources on the grid can't
    provide the equivalent of "inertia", to stabilize the grid?

    It seems to me the only issue is normally renewable power sources are optimized to
    provide the maximum power possible, so if the grid frequency slows (because there
    is less power sourced than the power drained), renewable power generation is already maxed out.
    ** What happens now is that inverters feeding the grid *track* the existing frequency - cos they are minor players in supplying the load.
    But what if that were not the case, they became the majority suppliers and and instead were locked to a central clock ?

    Rotating machines would then follow them.

    That's a weird thing to say. If the "inverters" were locked to a central clock and driving the grid,
    rotating generators would be no different than they are now, following the grid.

    ** Whaaaaaaatttttt ??????

    Insane, retarded crap.





    ...... Phil

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jeff Liebermann@21:1/5 to pallison49@gmail.com on Mon Apr 18 17:28:06 2022
    On Mon, 18 Apr 2022 14:51:38 -0700 (PDT), Phil Allison
    <pallison49@gmail.com> wrote:

    Ricky wrote:
    ===========

    Is there some fundamental reason why renewable power sources on the grid can't
    provide the equivalent of "inertia", to stabilize the grid?

    It seems to me the only issue is normally renewable power sources are optimized to
    provide the maximum power possible, so if the grid frequency slows (because there
    is less power sourced than the power drained), renewable power generation is already maxed out.

    ** What happens now is that inverters feeding the grid *track* the existing frequency - cos they are minor players in supplying the load.
    But what if that were not the case, they became the majority suppliers and and instead were locked to a central clock ?

    Rotating machines would then follow them.

    ...... Phil

    Synchronizing grid tied inverters and generators using GPS clocks and
    GPS disciplined oscillators is a common topic for green research
    papers. For example:
    "How Microsynchrophasors Could Keep Solar-Saturated Grids Stable" <https://www.greentechmedia.com/articles/read/How-Microsynchrophasors-Could-Keep-Solar-Saturated-Grids-Stable>

    The fun begins if the grid frequency slows down a little due to a
    decrease in source supply or an increase in load. A short while
    later, the generators are adjusted to bring everything back to exactly
    50 or 60Hz. However, that's not good because the frequency also needs
    to be adjusted to compensate for the time lost during the power sag.
    Otherwise, all the power line driven synchronous motor clocks would
    runs slow. So, the frequency of the entire grid needs to be increased
    slightly until the lost milliseconds are recovered, when it is now
    safe to return to exactly 50 or 60Hz. This explains the basics of how
    it's done:
    <https://www.mainsfrequency.com/gridtime.php>
    Notice that the example shows that Swiss time was 160 seconds behind
    UTC in June 2013. At 50Hz, that's
    160sec * 50cycles/sec = 8,000
    clock cycles that need to added to the grid for grid time to catch up
    with UTC time. Looking at the graph (blue line), time still hasn't
    caught up 6 months later.

    Bottom line is that synchronizing grid tied inverters is certainly
    possible, but isn't quite as simple as it might initially appear.

    Trivia For UK grid:
    <http://www.gridwatch.templar.co.uk> <https://jeelabs.org/2016/06/keeping-track-of-time/> <https://www.dynamicdemand.co.uk/grid.htm>
    <https://www.mainsfrequency.com>



    --
    Jeff Liebermann jeffl@cruzio.com
    PO Box 272 http://www.LearnByDestroying.com
    Ben Lomond CA 95005-0272
    Skype: JeffLiebermann AE6KS 831-336-2558

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Allison@21:1/5 to jeff.li...@gmail.com on Mon Apr 18 18:13:17 2022
    jeff.li...@gmail.com wrote:
    ======================
    Phil Allison

    ** What happens now is that inverters feeding the grid *track* the existing frequency - cos they are minor players in supplying the load.
    But what if that were not the case, they became the majority suppliers and and instead were locked to a central clock ?

    Rotating machines would then follow them.

    Synchronizing grid tied inverters and generators using GPS clocks and
    GPS disciplined oscillators is a common topic for green research
    papers.

    ** Nice to know, I was just speculating.

    The fun begins if the grid frequency slows down a little due to a
    decrease in source supply or an increase in load.

    ** Errrr - why ??

    Alternators naturally slow in reaction to load, but not inverters.
    Plus all alternators in a grid are locked together in phase.




    ...... Phil

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Ricky@21:1/5 to palli...@gmail.com on Mon Apr 18 18:52:57 2022
    On Monday, April 18, 2022 at 8:07:58 PM UTC-4, palli...@gmail.com wrote:
    Ricky the IDIOT wrote:
    ==================

    Is there some fundamental reason why renewable power sources on the grid can't
    provide the equivalent of "inertia", to stabilize the grid?

    It seems to me the only issue is normally renewable power sources are optimized to
    provide the maximum power possible, so if the grid frequency slows (because there
    is less power sourced than the power drained), renewable power generation is already maxed out.
    ** What happens now is that inverters feeding the grid *track* the existing frequency - cos they are minor players in supplying the load.
    But what if that were not the case, they became the majority suppliers and and instead were locked to a central clock ?

    Rotating machines would then follow them.

    That's a weird thing to say. If the "inverters" were locked to a central clock and driving the grid,
    rotating generators would be no different than they are now, following the grid.
    ** Whaaaaaaatttttt ??????

    Insane, retarded crap.

    Ah, Phil speak for he doesn't understand.

    --

    Rick C.

    +- Get 1,000 miles of free Supercharging
    +- Tesla referral code - https://ts.la/richard11209

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Ricky@21:1/5 to jeff.li...@gmail.com on Mon Apr 18 19:08:01 2022
    On Monday, April 18, 2022 at 8:28:18 PM UTC-4, jeff.li...@gmail.com wrote:
    On Mon, 18 Apr 2022 14:51:38 -0700 (PDT), Phil Allison
    <palli...@gmail.com> wrote:

    Ricky wrote:
    ===========

    Is there some fundamental reason why renewable power sources on the grid can't
    provide the equivalent of "inertia", to stabilize the grid?

    It seems to me the only issue is normally renewable power sources are optimized to
    provide the maximum power possible, so if the grid frequency slows (because there
    is less power sourced than the power drained), renewable power generation is already maxed out.

    ** What happens now is that inverters feeding the grid *track* the existing frequency - cos they are minor players in supplying the load.
    But what if that were not the case, they became the majority suppliers and and instead were locked to a central clock ?

    Rotating machines would then follow them.

    ...... Phil
    Synchronizing grid tied inverters and generators using GPS clocks and
    GPS disciplined oscillators is a common topic for green research
    papers. For example:
    "How Microsynchrophasors Could Keep Solar-Saturated Grids Stable" <https://www.greentechmedia.com/articles/read/How-Microsynchrophasors-Could-Keep-Solar-Saturated-Grids-Stable>

    The fun begins if the grid frequency slows down a little due to a
    decrease in source supply or an increase in load. A short while
    later, the generators are adjusted to bring everything back to exactly
    50 or 60Hz. However, that's not good because the frequency also needs
    to be adjusted to compensate for the time lost during the power sag. Otherwise, all the power line driven synchronous motor clocks would
    runs slow. So, the frequency of the entire grid needs to be increased slightly until the lost milliseconds are recovered, when it is now
    safe to return to exactly 50 or 60Hz. This explains the basics of how
    it's done:
    <https://www.mainsfrequency.com/gridtime.php>
    Notice that the example shows that Swiss time was 160 seconds behind
    UTC in June 2013. At 50Hz, that's
    160sec * 50cycles/sec = 8,000
    clock cycles that need to added to the grid for grid time to catch up
    with UTC time. Looking at the graph (blue line), time still hasn't
    caught up 6 months later.

    Bottom line is that synchronizing grid tied inverters is certainly
    possible, but isn't quite as simple as it might initially appear.

    I don't know about Switzerland, but in the US, didn't they throw in the towel on supporting synchronous clocks? I think that happened over 10 years ago. Maybe I was misinformed. I found an article at the IEEE from 2011 about a year long experiment
    where they were going to stop correcting the grid to see how many people complained. I didn't find anything about the result.

    --

    Rick C.

    ++ Get 1,000 miles of free Supercharging
    ++ Tesla referral code - https://ts.la/richard11209

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jeff Liebermann@21:1/5 to gnuarm.deletethisbit@gmail.com on Mon Apr 18 21:23:27 2022
    On Mon, 18 Apr 2022 19:08:01 -0700 (PDT), Ricky <gnuarm.deletethisbit@gmail.com> wrote:

    I don't know about Switzerland, but in the US, didn't they throw in the towel on supporting synchronous clocks? I think that happened over 10 years ago. Maybe I was misinformed. I found an article at the IEEE from 2011 about a year long experiment
    where they were going to stop correcting the grid to see how many people complained. I didn't find anything about the result.

    This is probably the 2011 paper about the test: <https://phys.org/news/2011-06-power-grid-disrupt-clocks.html>

    Reports started to appear a few years later. However, I can't tell if
    the 1 year test was actually performed. This report looks like it was
    done using historical data from a power line frequency monitoring
    network:
    "Impacts of Power Grid Frequency Deviation on Time
    Error of Synchronous Electric Clock and Worldwide
    Power System Practices on Time Error Correction" <https://mdpi-res.com/d_attachment/energies/energies-10-01283/article_deploy/energies-10-01283.pdf>
    "On the other hand, the identification results present that up to the
    end of 2016, many electric utilities around the world, especially in
    North America and Europe, provided the TEC service to periodically
    remove the accumulative time error of synchronous electric clocks."

    This CAISO document indicates that TEC (time error correction) was
    active in western USA at least up to 2019: <https://www.caiso.com/documents/rc0220.pdf>

    This 2021 document indicates that in the event of an emergency, time
    error correction can be temporarily suspended until things sort
    themselves out:
    <https://www.caiso.com/Documents/4420.pdf>

    Kinda looks like TEC is currently alive and well, at least for some
    grid operators.

    Drivel: Old technology doesn't completely die out, even after several generations of superior technologies. For example: <https://www.google.com/search?q=swimming+pool+timer&tbm=isch>


    --
    Jeff Liebermann jeffl@cruzio.com
    PO Box 272 http://www.LearnByDestroying.com
    Ben Lomond CA 95005-0272
    Skype: JeffLiebermann AE6KS 831-336-2558

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Bertrand Sindri@21:1/5 to Jeff Liebermann on Tue Apr 19 15:53:36 2022
    Jeff Liebermann <jeffl@cruzio.com> wrote:
    The fun begins if the grid frequency slows down a little due to a
    decrease in source supply or an increase in load. A short while
    later, the generators are adjusted to bring everything back to exactly
    50 or 60Hz. However, that's not good because the frequency also needs
    to be adjusted to compensate for the time lost during the power sag.

    Time error correction is no longer done in the US after 2017:

    https://www.usatoday.com/story/money/economy/2018/05/17/clocks-may-change-power-grid-maintenance-rule/619864002/

    "... so last year, the correction part was quietly eliminated by the
    Federal Energy Regulatory Commission."

    https://www.balch.com/insights/publications/2017/01/www.balch.com/-/media/erl-blog/fercordersrulesdelegated-order-approving-retirement-for-reliability-standard-bal0040.pdf

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jeff Liebermann@21:1/5 to bertrand.sindri@yahoo.com on Tue Apr 19 10:20:06 2022
    On Tue, 19 Apr 2022 15:53:36 -0000 (UTC), Bertrand Sindri <bertrand.sindri@yahoo.com> wrote:

    Jeff Liebermann <jeffl@cruzio.com> wrote:
    The fun begins if the grid frequency slows down a little due to a
    decrease in source supply or an increase in load. A short while
    later, the generators are adjusted to bring everything back to exactly
    50 or 60Hz. However, that's not good because the frequency also needs
    to be adjusted to compensate for the time lost during the power sag.

    Time error correction is no longer done in the US after 2017:

    https://www.usatoday.com/story/money/economy/2018/05/17/clocks-may-change-power-grid-maintenance-rule/619864002/

    "... so last year, the correction part was quietly eliminated by the
    Federal Energy Regulatory Commission."

    https://www.balch.com/insights/publications/2017/01/www.balch.com/-/media/erl-blog/fercordersrulesdelegated-order-approving-retirement-for-reliability-standard-bal0040.pdf

    Thanks. The above document seems to suggest that it's only replacing
    one standard (BAL-003-xxx) with a new and improved version
    (BAL-004-0). Without reading the standard, I can't tell if TEC (time
    error correction) is still being performed using a new and improved
    TEC procedure or standard. I said "seems to suggest" because I'm
    having difficulties decoding the legalese.

    Quoting:
    NERC explains that since Reliability Standard
    BAL-004-0 became effective, improvements have been
    made to mandatory Reliability Standards (such as
    the development of Reliability Standards BAL-003-1.1
    and BAL-001-2 and the Interconnection Reliability
    Operations and Coordination (IRO) Standards) that
    help ensure continued adherence to frequency
    approximating 60 Hertz over long-term averages and
    make Reliability Standard BAL-004-0 redundant.

    Note that "continued adherence to frequency..." indicates that
    something is being done to maintain a "long-term average" 60Hz. If
    synchronous clocks were not an issue, there would be no need for this "long-term average". Also, just because it is no longer a regulatory requirement to maintain clock sync doesn't prevent the utilities from
    doing it anyway possibly because no utility wants to be first to be
    identified as causing a problem with some forgotten device due to an
    oversight. Also note that compliance to this reliability standard is voluntary, not mandatory: <https://www.nerc.com/pa/Stand/Pages/SARUrgentActionBAL004.aspx>
    "Time Monitor is a voluntary service and, therefore, should not be
    penalized for non compliance." Note that this was done in 2008.


    --
    Jeff Liebermann jeffl@cruzio.com
    PO Box 272 http://www.LearnByDestroying.com
    Ben Lomond CA 95005-0272
    Skype: JeffLiebermann AE6KS 831-336-2558

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Allison@21:1/5 to jeff.li...@gmail.com on Tue Apr 19 15:15:51 2022
    jeff.li...@gmail.com wrote:
    ==================

    ** What happens now is that inverters feeding the grid *track* the existing frequency - cos they are minor players in supplying the load.
    But what if that were not the case, they became the majority suppliers and and instead were locked to a central clock ?

    Rotating machines would then follow them.

    ...... Phil

    The fun begins if the grid frequency slows down a little due to a
    decrease in source supply or an increase in load. A short while
    later, the generators are adjusted to bring everything back to exactly
    50 or 60Hz.


    ** That is not what really happens.

    The supply frequency is in constant, slow oscillation around the nominal 50 or 60Hz.
    Anyone with a period counter or a scope in X-Y mode can verify this.

    Excursions are limited to about +/- 0.1 Hz and take several minutes per cycle. There are web pages that show this in real time too.

    In any case, the millions of mostly electronic clocks that rely on this frequency cannot be trusted due to the high probability of local outages and tripping circuit breakers.


    ...... Phil

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Ricky@21:1/5 to palli...@gmail.com on Tue Apr 19 15:53:23 2022
    On Tuesday, April 19, 2022 at 6:15:55 PM UTC-4, palli...@gmail.com wrote:
    jeff.li...@gmail.com wrote:
    ==================

    ** What happens now is that inverters feeding the grid *track* the existing frequency - cos they are minor players in supplying the load.
    But what if that were not the case, they became the majority suppliers and and instead were locked to a central clock ?

    Rotating machines would then follow them.

    ...... Phil

    The fun begins if the grid frequency slows down a little due to a
    decrease in source supply or an increase in load. A short while
    later, the generators are adjusted to bring everything back to exactly
    50 or 60Hz.

    ** That is not what really happens.

    The supply frequency is in constant, slow oscillation around the nominal 50 or 60Hz.
    Anyone with a period counter or a scope in X-Y mode can verify this.

    Excursions are limited to about +/- 0.1 Hz and take several minutes per cycle.
    There are web pages that show this in real time too.

    In any case, the millions of mostly electronic clocks that rely on this frequency cannot be trusted due to the high probability of local outages and tripping circuit breakers.

    So, mismatches in generation and load do not result in a change in frequency? That's an interesting idea. So where does rotational inertia come in?

    --

    Rick C.

    --- Get 1,000 miles of free Supercharging
    --- Tesla referral code - https://ts.la/richard11209

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Martin Brown@21:1/5 to Ricky on Wed Apr 20 09:49:30 2022
    On 18/04/2022 15:43, Ricky wrote:
    On Monday, April 18, 2022 at 5:45:31 AM UTC-4, Martin Brown wrote:

    The calculation that wasn't allowed for in the UK is that with
    domestic generation on home roofs and on a sunny day when you shed
    "load" you will also shed a whole bunch of local solar PV
    generation as well.

    Let's leave the small, domestic systems out of the conversation.

    But they are critical to understanding one of the key modes of failure
    that took down so much of the UK grid. Roughly 2% of roofs have solar
    panels on each producing 4kW in good sunlight and at a time when average household load is about 200W so per thousand homes you have:

    200kW load and 80kW local solar PV. The system tried to stabilise itself
    by shedding 1MW of load but at the same time it lost 400kW of local
    generation as well and so had to keep on dropping chunks off supply. It
    was always behind the curve at every step of the way. The algorithm
    expected to overshoot and then be able to reconnect. It didn't happen.

    As the number of homes with solar PV increases it becomes harder and
    harder to ignore this effect at >5% they become net exporters at least
    when the sun is shining.

    The particular point someone was making was that no inverters used
    with wind power (or solar farms) has the ability to help stabilize
    the grid, because there is no rotating inertia. It was not claimed
    that this was not possible, but it was implied by pointing out no one
    had done this yet and it would be a very useful feature.

    There is some rotating inertia in the spinning wind turbine blades but
    nothing like as much as there is in a big mechanical steam turbine but
    enough to keep going provided that you allow the frequency to drift.

    Seems to me it would require some way of increasing the power output,
    which means the facility has to run below optimal efficiency to have
    anything in reserve.

    One way to build some resilience is to have local battery storage that
    is immediately available to boost output when there is a sudden change
    in load. US & Australia has a fair sized one to control peak loading.

    https://www.bbc.com/future/article/20201217-renewable-power-the-worlds-largest-battery

    UK has one but it is a complete toy and wasn't in the right place to do
    any good last time. UK has a structural problem in that most power is
    generated in the north and shipped down to the south to be used. The
    upshot of this if they lose either of the big N-S EHT supergrid lines
    then the south is very short of electricity and something has to give.

    Pumped storage reservoirs are our most effective load balancing tool for immediate generation of more power. Routine balancing is done by
    adjusting power delivered the ultimate sink loads (on very favourable intermittent tariffs). Unfortunately if you have already asked them to
    power down you don't have that option (as has occurred some winters).

    The advantage of natural inertia, is the continuous nature. As much
    energy as is needed is available if you are able to tolerate the
    reduction in frequency. Of course, there is a limit to the inertia available, but it seems to do the job pretty well in most cases,
    while currently we seem to get nothing from solar and wind power
    facilities.

    You can still simulate inertia by allowing the inverter to drift further
    off frequency than the standard rules would normally allow. Something
    like this tweak has been done to avoid quite so much chaos next time.

    I presume that they have fixed the assumptions that caused the load
    shedding algorithms to misjudge how much *absolute* load they would
    have to drop to obtain a net saving of 1MW in future. It was a pretty catastrophic mode of cascade systems failure for what should have been a routine lightning strike with local cutout protection and recovery.

    I don't think it would be such a problem in the USA since peak solar PV
    output and peak domestic aircon requirements more or less balance it
    out. In the UK there is hardly any domestic aircon so that in sunny
    weather most of what is generated by domestic PV is exported to the grid (especially in the late afternoon).

    A stupid feature of the UK's "green" feed in tariff makes it cost
    effective to have solar PV power and turn it into domestic hot water!
    After market gizmos abound to do this automatically. You are deemed to
    export half of what you generate irrespective of using it or not.

    --
    Regards,
    Martin Brown

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Martin Brown@21:1/5 to Ricky on Wed Apr 20 09:53:02 2022
    On 19/04/2022 23:53, Ricky wrote:
    On Tuesday, April 19, 2022 at 6:15:55 PM UTC-4, palli...@gmail.com wrote:
    jeff.li...@gmail.com wrote:
    ==================

    ** What happens now is that inverters feeding the grid *track* the existing frequency - cos they are minor players in supplying the load.
    But what if that were not the case, they became the majority suppliers and and instead were locked to a central clock ?

    Rotating machines would then follow them.

    ...... Phil

    The fun begins if the grid frequency slows down a little due to a
    decrease in source supply or an increase in load. A short while
    later, the generators are adjusted to bring everything back to exactly
    50 or 60Hz.

    ** That is not what really happens.

    The supply frequency is in constant, slow oscillation around the nominal 50 or 60Hz.
    Anyone with a period counter or a scope in X-Y mode can verify this.

    Excursions are limited to about +/- 0.1 Hz and take several minutes per cycle.
    There are web pages that show this in real time too.

    In general it often tends to run consistently slow when the loads are at highest peak (like evening meal time in the UK) or peak afternoon aircon
    load in the USA and consistently fast in the middle of the night.

    The latter used to be a nuisance for some old school telescope drives
    that were mains synchronous motor based. When you are tracking to arc
    second precision the mains just isn't accurate enough. They moved to
    quartz crystal references or servo with autoguider pretty much as soon
    as the technology became available. Much less work for the observer.

    In any case, the millions of mostly electronic clocks that rely on this frequency cannot be trusted due to the high probability of local outages and tripping circuit breakers.

    Quite a lot of traffic lights still rely on it too.

    The advent of cheap VLF time modules has made it much less of a problem.
    Mains powered synchronous motor based kit has all but died out now. But
    there are plenty of legacy traffic lights that need resetting after a
    long powercut (since they tend to resume from whatever time they were at
    when the power goes down). A few minutes is fairly harmless but a few
    hours and the rush hour traffic flows end up in total chaos.

    So, mismatches in generation and load do not result in a change in frequency? That's an interesting idea. So where does rotational inertia come in?

    That isn't what he said.

    They have always allowed the mains frequency to drift slightly with time
    to accommodate minor imbalances in the load at peak times. Heavy load
    means lower frequency and lighter loads the allow it to run a bit fast.
    It hunts slowly around the nominal frequency since if they predict that
    load will increase they will bring more generation onstream.

    To keep dead reckoning mains powered clocks based on synchronous motors accurate they increase the frequency slightly when the loads are lowest
    in the middle of the night. The average mains frequency over 24 hours
    is held to very high precision linked back to atomic time standards.
    (from what others have said it seems the USA have relaxed this rule)

    Network phase in the UK is relatively well defined since 800km << 6000km
    (one wavelength at 50Hz).

    But in the USA where network distances are much greater the network
    phase must be locally determined. eg. SF to NY is ~4000km which is a
    very non-negligible fraction of a 60hz wavelength of 5000km.

    --
    Regards,
    Martin Brown

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Allison@21:1/5 to Martin Bullshit LIAR Brown on Wed Apr 20 02:44:22 2022
    Martin Bullshit LIAR Brown wrote:

    =============================


    ** What happens now is that inverters feeding the grid *track* the existing frequency - cos they are minor players in supplying the load.
    But what if that were not the case, they became the majority suppliers and and instead were locked to a central clock ?

    Rotating machines would then follow them.

    ...... Phil

    The fun begins if the grid frequency slows down a little due to a
    decrease in source supply or an increase in load. A short while
    later, the generators are adjusted to bring everything back to exactly >>> 50 or 60Hz.

    ** That is not what really happens.

    The supply frequency is in constant, slow oscillation around the nominal 50 or 60Hz.
    Anyone with a period counter or a scope in X-Y mode can verify this.

    Excursions are limited to about +/- 0.1 Hz and take several minutes per cycle.
    There are web pages that show this in real time too.

    In general it often tends to run consistently slow when the loads are at highest peak (like evening meal time in the UK) or peak afternoon aircon
    load in the USA and consistently fast in the middle of the night.


    ** So you have never checked the *actual frequency* or followed on-line pages that give a 24/7 readout.
    Your whole bullshit is just fucking made up.

    LIKE EVERY POST YOU HAVE EVER MADE !!
    -----------------------------------------------------------------------------



    In any case, the millions of mostly electronic clocks that rely on this frequency
    cannot be trusted due to the high probability of local outages and tripping circuit breakers.

    Quite a lot of traffic lights still rely on it too.

    ** FFS what a fucking ridiculous red herring !!!


    So, mismatches in generation and load do not result in a change in frequency?
    That's an interesting idea. So where does rotational inertia come in?

    That isn't what he said.

    ** At least you got that one right.

    Ricky is a total fucking, bullshitting ASD fucked IDIOT .
    So are YOU !!!


    They have always allowed the mains frequency to drift slightly with time
    to accommodate minor imbalances in the load at peak times.

    ** Bullshit.

    Heavy load means lower frequency

    ** Bullshit.

    and lighter loads the allow it to run a bit fast.

    ** Bullshit.

    It hunts slowly around the nominal frequency since if they predict that
    load will increase they will bring more generation onstream.

    ** Bullshit.

    To keep dead reckoning mains powered clocks based on synchronous motors accurate they increase the frequency slightly when the loads are lowest
    in the middle of the night.

    ** Bullshit.


    ..... Phil

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don Y@21:1/5 to Martin Brown on Wed Apr 20 06:35:16 2022
    On 4/20/2022 1:53 AM, Martin Brown wrote:

    They have always allowed the mains frequency to drift slightly with time to accommodate minor imbalances in the load at peak times. Heavy load means lower
    frequency and lighter loads the allow it to run a bit fast. It hunts slowly around the nominal frequency since if they predict that load will increase they
    will bring more generation onstream.

    To keep dead reckoning mains powered clocks based on synchronous motors accurate they increase the frequency slightly when the loads are lowest in the
    middle of the night. The average mains frequency over 24 hours is held to very
    high precision linked back to atomic time standards.

    In the early-mid 70's, I wanted a clock that wouldn't have to deal with
    the silly time changes so designed one around a 10MHz TCXO that we happened
    to use in one of our products. I was chagrined to discover it was off several seconds each month -- until I looked at the tolerance on the oscillator
    (a few PPM).

    As I couldn't step *up* to an OCXO (too much power required to keep it operating through power outages), I looked to the mains as an alternate time source ("how can *regular* clocks keep such good time?"). Eventually, replacing all of the discrete logic with a processor I could "watch" the
    mains frequency vary (against the stable TCXO) over the course of a day.
    I.e., the mains-derived time had short-term stability problems but
    long-term accuracy.

    So, I fell upon the idea of using the mains frequency to tweek the TCXO's notion of time. Then, realized the TCXO was essentially unnecessary;
    any time source of sufficient short term stability could suffice -- if I
    could *measure* that frequency against the mains over VERY long intervals.

    Subsequent clocks have been built around cheap watch crystals/RTCs and
    keep remarkably good time (much better than an undisciplined PC). I now discipline my NTP server with such a source (I don't care if my PCs are
    "off" by N seconds -- as long as they are ALWAYS off by N seconds -- as
    this lets me operate without a GPS signal *or* routing them!)

    (from what others have said it seems the USA have relaxed this rule)

    I'd been told that was *supposed* to happen. But, haven't seen any practical consequences on any of my mains-disciplined clocks.

    Network phase in the UK is relatively well defined since 800km << 6000km (one wavelength at 50Hz).

    But in the USA where network distances are much greater the network phase must
    be locally determined. eg. SF to NY is ~4000km which is a very non-negligible fraction of a 60hz wavelength of 5000km.

    There is a group that (informally?) monitors this nationwide, here (US):
    <https://en.wikipedia.org/wiki/FNET>
    I question how reliable their phase measurements are, given that they are looking at "consumer" distributions and not the "backbone" of the
    power network. (but, *frequency* observations should be dead to nuts)

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From whit3rd@21:1/5 to palli...@gmail.com on Wed Apr 20 10:59:20 2022
    On Wednesday, April 20, 2022 at 2:44:26 AM UTC-7, palli...@gmail.com wrote:
    Martin Brown wrote:

    They have always allowed the mains frequency to drift slightly with time
    to accommodate minor imbalances in the load at peak times.
    ** Bullshit.

    Maybe; the 'drift slightly with time' sounds vague.

    Heavy load means lower frequency
    ** Bullshit.

    Not so. Rotating machinery generates that frequency, and heavy load
    on the generators does slow their rotation; regardless of control settings,
    the feedback gain cannot be infinite (that causes more problems than it solves).

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jeroen Belleman@21:1/5 to All on Wed Apr 20 20:16:26 2022
    On 2022-04-20 19:59, whit3rd wrote:
    On Wednesday, April 20, 2022 at 2:44:26 AM UTC-7, palli...@gmail.com wrote:
    Martin Brown wrote:

    They have always allowed the mains frequency to drift slightly with time >>> to accommodate minor imbalances in the load at peak times.
    ** Bullshit.

    Maybe; the 'drift slightly with time' sounds vague.

    Heavy load means lower frequency
    ** Bullshit.

    Not so. Rotating machinery generates that frequency, and heavy load
    on the generators does slow their rotation; regardless of control settings, the feedback gain cannot be infinite (that causes more problems than it solves).


    On the European mains network, the proportionality constant is
    about 20GW/Hz. All sufficiently large generating facilities are
    supposed to adjust their power output to drive the long-term
    average frequency to its nominal value. A Swiss source provides
    the reference frequency.

    Jeroen Belleman

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Ricky@21:1/5 to Martin Brown on Wed Apr 20 13:50:11 2022
    On Wednesday, April 20, 2022 at 4:49:38 AM UTC-4, Martin Brown wrote:
    On 18/04/2022 15:43, Ricky wrote:
    On Monday, April 18, 2022 at 5:45:31 AM UTC-4, Martin Brown wrote:

    The calculation that wasn't allowed for in the UK is that with
    domestic generation on home roofs and on a sunny day when you shed
    "load" you will also shed a whole bunch of local solar PV
    generation as well.

    Let's leave the small, domestic systems out of the conversation.
    But they are critical to understanding one of the key modes of failure
    that took down so much of the UK grid. Roughly 2% of roofs have solar
    panels on each producing 4kW in good sunlight and at a time when average household load is about 200W so per thousand homes you have:

    200kW load and 80kW local solar PV. The system tried to stabilise itself
    by shedding 1MW of load but at the same time it lost 400kW of local generation as well and so had to keep on dropping chunks off supply. It
    was always behind the curve at every step of the way. The algorithm
    expected to overshoot and then be able to reconnect. It didn't happen.

    As the number of homes with solar PV increases it becomes harder and
    harder to ignore this effect at >5% they become net exporters at least
    when the sun is shining.

    I don't care about the issues in the UK. You and others have stated many times that the UK grid is bollixed up beyond all redemption. So not much to learn from it for a real grid.


    The particular point someone was making was that no inverters used
    with wind power (or solar farms) has the ability to help stabilize
    the grid, because there is no rotating inertia. It was not claimed
    that this was not possible, but it was implied by pointing out no one
    had done this yet and it would be a very useful feature.
    There is some rotating inertia in the spinning wind turbine blades but nothing like as much as there is in a big mechanical steam turbine but
    enough to keep going provided that you allow the frequency to drift.
    Seems to me it would require some way of increasing the power output,
    which means the facility has to run below optimal efficiency to have anything in reserve.
    One way to build some resilience is to have local battery storage that
    is immediately available to boost output when there is a sudden change
    in load. US & Australia has a fair sized one to control peak loading.

    https://www.bbc.com/future/article/20201217-renewable-power-the-worlds-largest-battery

    UK has one but it is a complete toy and wasn't in the right place to do
    any good last time. UK has a structural problem in that most power is generated in the north and shipped down to the south to be used. The
    upshot of this if they lose either of the big N-S EHT supergrid lines
    then the south is very short of electricity and something has to give.

    Pumped storage reservoirs are our most effective load balancing tool for immediate generation of more power. Routine balancing is done by
    adjusting power delivered the ultimate sink loads (on very favourable intermittent tariffs). Unfortunately if you have already asked them to
    power down you don't have that option (as has occurred some winters).

    Yes, yes, yes, but not what we are discussing.


    The advantage of natural inertia, is the continuous nature. As much
    energy as is needed is available if you are able to tolerate the
    reduction in frequency. Of course, there is a limit to the inertia available, but it seems to do the job pretty well in most cases,
    while currently we seem to get nothing from solar and wind power facilities.
    You can still simulate inertia by allowing the inverter to drift further
    off frequency than the standard rules would normally allow. Something
    like this tweak has been done to avoid quite so much chaos next time.

    I presume that they have fixed the assumptions that caused the load
    shedding algorithms to misjudge how much *absolute* load they would
    have to drop to obtain a net saving of 1MW in future. It was a pretty catastrophic mode of cascade systems failure for what should have been a routine lightning strike with local cutout protection and recovery.

    I don't think it would be such a problem in the USA since peak solar PV output and peak domestic aircon requirements more or less balance it
    out. In the UK there is hardly any domestic aircon so that in sunny
    weather most of what is generated by domestic PV is exported to the grid (especially in the late afternoon).

    A stupid feature of the UK's "green" feed in tariff makes it cost
    effective to have solar PV power and turn it into domestic hot water!
    After market gizmos abound to do this automatically. You are deemed to
    export half of what you generate irrespective of using it or not.

    Yes, you keep telling us how bad the UK grid is. I agree.

    --

    Rick C.

    --+ Get 1,000 miles of free Supercharging
    --+ Tesla referral code - https://ts.la/richard11209

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Ricky@21:1/5 to All on Wed Apr 20 14:24:09 2022
    On Wednesday, April 20, 2022 at 1:59:24 PM UTC-4, whit3rd wrote:
    On Wednesday, April 20, 2022 at 2:44:26 AM UTC-7, palli...@gmail.com wrote:
    Martin Brown wrote:

    They have always allowed the mains frequency to drift slightly with time to accommodate minor imbalances in the load at peak times.
    ** Bullshit.
    Maybe; the 'drift slightly with time' sounds vague.
    Heavy load means lower frequency
    ** Bullshit.
    Not so. Rotating machinery generates that frequency, and heavy load
    on the generators does slow their rotation; regardless of control settings, the feedback gain cannot be infinite (that causes more problems than it solves).

    No, that's not quite right. It is the balance between load and supply that causes the frequency drift. Too much energy feeding into the generators and the frequency increases as the excess is absorbed by the rotational inertia. Too little energy
    feeding into the generators and the frequency decreases as the inertia is drawn down to supply the excess load. The difference in source and load match determines the derivative of the frequency.

    --

    Rick C.

    -+- Get 1,000 miles of free Supercharging
    -+- Tesla referral code - https://ts.la/richard11209

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Ricky@21:1/5 to Glen Walpert on Wed Apr 20 15:37:29 2022
    On Wednesday, April 20, 2022 at 6:21:31 PM UTC-4, Glen Walpert wrote:
    On Wed, 20 Apr 2022 10:59:20 -0700 (PDT), whit3rd wrote:

    On Wednesday, April 20, 2022 at 2:44:26 AM UTC-7, palli...@gmail.com wrote:
    Martin Brown wrote:

    They have always allowed the mains frequency to drift slightly with
    time to accommodate minor imbalances in the load at peak times.
    ** Bullshit.

    Maybe; the 'drift slightly with time' sounds vague.

    Heavy load means lower frequency
    ** Bullshit.

    Not so. Rotating machinery generates that frequency, and heavy load on
    the generators does slow their rotation; regardless of control settings, the feedback gain cannot be infinite (that causes more problems than it solves).
    Right. In single generator operation the governor will be set to
    constant frequency mode, and will hold a constant frequency at all
    loads. But in order to parallel generators and share the load in a
    stable manner the governors must be placed in droop mode, where a
    percentage of power level is subtracted from the governors set point.
    When paralleled with a much larger bus, the governor cannot regulate generator speed, that is locked to the grid, it regulates real power
    output instead. Connect initially with no load and slightly higher speed
    at matched phase and the generator picks up a minute load, then if droop
    is set at 5% for instance cranking up the governor speed knob 5% will
    give you full load. So all rotating generators on the grid provide more power as frequency drops and less as it rises, more power delivered tends
    to up frequency, less reduces. Power delivery is set by the central grid operator for all large generating stations in order to match the load and thus keep frequency ~constant.

    The part I'm not clear on is how this is combined with the financial side of things. There are various load accounts and what you describe is generation essentially in bulk. No generator is outputing a specific amount as contracted for by customers.
    So how does the billing work? If user A, B and C have contracted with supplier K, but supplier K is having to output power according to central control, who is paying supplier K for all the MWh being pumped out if it doesn't match what his customers A,
    B and C are asking for?

    --

    Rick C.

    -++ Get 1,000 miles of free Supercharging
    -++ Tesla referral code - https://ts.la/richard11209 0

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Glen Walpert@21:1/5 to All on Wed Apr 20 22:21:23 2022
    On Wed, 20 Apr 2022 10:59:20 -0700 (PDT), whit3rd wrote:

    On Wednesday, April 20, 2022 at 2:44:26 AM UTC-7, palli...@gmail.com
    wrote:
    Martin Brown wrote:

    They have always allowed the mains frequency to drift slightly with
    time to accommodate minor imbalances in the load at peak times.
    ** Bullshit.

    Maybe; the 'drift slightly with time' sounds vague.

    Heavy load means lower frequency
    ** Bullshit.

    Not so. Rotating machinery generates that frequency, and heavy load on
    the generators does slow their rotation; regardless of control settings,
    the feedback gain cannot be infinite (that causes more problems than it solves).

    Right. In single generator operation the governor will be set to
    constant frequency mode, and will hold a constant frequency at all
    loads. But in order to parallel generators and share the load in a
    stable manner the governors must be placed in droop mode, where a
    percentage of power level is subtracted from the governors set point.
    When paralleled with a much larger bus, the governor cannot regulate
    generator speed, that is locked to the grid, it regulates real power
    output instead. Connect initially with no load and slightly higher speed
    at matched phase and the generator picks up a minute load, then if droop
    is set at 5% for instance cranking up the governor speed knob 5% will
    give you full load. So all rotating generators on the grid provide more
    power as frequency drops and less as it rises, more power delivered tends
    to up frequency, less reduces. Power delivery is set by the central grid operator for all large generating stations in order to match the load and
    thus keep frequency ~constant.

    There is a similar situation with voltage regulation, in single generator operation the field exciter regulates voltage. When paralleled with an "infinite bus" the exciter can no longer regulate voltage, it
    automatically (via aux contacts on the paralleling breaker) goes into
    reactive power regulating mode, initially set at zero reactive power if voltages were matched when paralleling and left there unless the utility
    pays for reactive power. Multiple generators at the same location are
    cross compensated to share reactive power, and reactive power on the grid
    is balanced by the grid operator. There are some interesting stability
    issues with reactive power since it has twice the effect on rotating
    generator voltage as real power, but this is well understood if not easy
    to remedy - as static synchronous generators increase in % total grid
    power and need to contribute reactive power it will be necessary to turn
    some control of them over to the grid operator, as is already being done
    in some places, and as was done long ago to stop power sloshing between rotating generator power plants on the same grid.

    (Grid goes undervoltage, SSG's up reactive power, grid voltage goes up,
    SSG's drop reactive power, grid goes undervoltage, etc. Better control strategy will stop this.)

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Anthony William Sloman@21:1/5 to Ricky on Wed Apr 20 20:05:22 2022
    On Thursday, April 21, 2022 at 8:37:33 AM UTC+10, Ricky wrote:
    On Wednesday, April 20, 2022 at 6:21:31 PM UTC-4, Glen Walpert wrote:
    On Wed, 20 Apr 2022 10:59:20 -0700 (PDT), whit3rd wrote:
    On Wednesday, April 20, 2022 at 2:44:26 AM UTC-7, palli...@gmail.com wrote:
    Martin Brown wrote:

    <snip>

    The part I'm not clear on is how this is combined with the financial side of things. There are various load accounts and what you describe is generation essentially in bulk. No generator is outputing a specific amount as contracted for by customers. So
    how does the billing work? If user A, B and C have contracted with supplier K, but supplier K is having to output power according to central control, who is paying supplier K for all the MWh being pumped out if it doesn't match what his customers A, B
    and C are asking for?

    In Australia there was an auction every half hour - it's now every ten minutes - where the generating companies would offer power to the distribution company which would buy up as much as was needed to satisfy demand, and reject the rest.

    The people who retailed the power to their customers at a fixed price per kilowatt hour had to pay for what they took out over that period at the auction price. The price fluctuates a lot.

    https://aemo.com.au/en/energy-systems/electricity/national-electricity-market-nem/market-operations/settlements-and-payments/settlements/settlements-residue-auction/guide-to-settlements-residue-auction

    https://www.aer.gov.au/wholesale-markets/wholesale-statistics?f%5B0%5D=field_accc_aer_sector%3A4

    It all seems to work. Fast start gas-turbine-driven generation only gets turned when the price is likely to be high. Grid-scale batteries and pumped storage can offer power immediately, when the price is high enough. About half the Tesla battery in South
    Australia is used to buy up power when it is cheap and sell it back when it isn't. It makes enough out of it to pay for itself over a decade.

    --
    Bill Sloman, Sydney

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)