Grid Stability and Renewable Power...

[Ricky]

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

 

[Anthony William Sloman]

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

 

[Klaus Kragelund]

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

 

[Anthony William Sloman]

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

 

[Phil Allison]

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

 

[whit3rd]

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.

 

[Jan Panteltje]

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/

 

[Martin Brown]

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

 

[Glen Walpert]

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

 

[Ricky]

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

 

[Ricky]

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

 

[Phil Allison]

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

 

[Ricky]

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

 

[Phil Allison]

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

 

[Jeff Liebermann]

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

 

[Phil Allison]

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

 

[Ricky]

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

 

[Ricky]

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

 

[Jeff Liebermann]

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

 

[Bertrand Sindri]

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