OT: 'Photon Farming' in California

[Rick C]

On Sunday, August 11, 2019 at 2:10:45 AM UTC-4, upsid...@downunder.com wrote:

On Sat, 10 Aug 2019 17:17:09 -0700 (PDT), Bill Sloman
bill.sloman@ieee.org> wrote:

On Sunday, August 11, 2019 at 2:03:40 AM UTC+10, upsid...@downunder.com wrote:
On Sat, 10 Aug 2019 13:52:03 +0100, Martin Brown
'''newspam'''@nezumi.demon.co.uk> wrote:

[1] There blackouts across the Midlands, the South East,
South West, North West and north east of England, and
Wales.

It seems likely that the initial problem which was the first gas turbine
generator dropping out wasn't dealt with in the two minutes before a
second independent failure of a wind turbine farm. The two being offline
together then took the mains frequency sufficiently far out of bounds
that some inverters stopped as well. Cascade failure followed.

It also may be that they had a bit bad luck.

Good network management requires that the N-1 rule is followed. The
network should survive the loss of _largest_ production unit. In
practice during the first minutes the spinning reserve of other power
plants are used (.i.e. overloading them). During that time quick
start emergency gas turbines are started, which then takes over from
the spinning reserve. When the emergency gas turbines are running, the
power of existing power plants are added e.g. by burning more coal to
get more steam or other slower starting power plants are starting.
When these are running, the emergency gas turbines can be shut down
and the N-1 criterion is restored, waiting for the loss of the next
largest production unit. These emergency gas turbines are typically
running for less than an hour.

However, as long as the emergency gas turbines are used, the network
doesn't tolerate the loss of the next largest unit.

When South Australia bought its big Telsa battery, with the fast inverter built in, it more or less immediately demonstrated the convience of having a really fast-acting voltage and frequency correcting device.

https://reneweconomy.com.au/how-the-tesla-big-battery-kept-the-lights-on-in-south-australia-20393/

Dinowig is fast, but not that fast.

snip

Originally the idea with the N-1 rule was that after the failure of
the largest production unit, the remaining production units can be
slightly overloaded for a while until new production capacity has ben
dispatched (spinning reserve).

This assumption is true with _BIG_ synchronous generators with can be
overloaded by 5 - 10 % for a minute or two without overheating too
much. Thus if a 1000 MW unit is lost the total grid on-line capacity
needs to be 10-20 GW, each of which can be overloaded by 5 - 10 %,

After this minute or two, fast starting emergency gas turbines or
diesels must be running so that the big generators can be scaled down
to nominal capacity.

However, a lot of renewable sources are inverter connected. These
inverters have no overload capacity or at most a few second capability
before overheating.

About a decade ago there was a huge wind energy boom in Germany due to
ample subsidies, so that every farmer wanted a wind turbine on their
field, no matter how bad the wind conditions are. These could also
sell all production to the net, this running at 100 % load as long as
there is wind.

In a fault condition. when all remaining production were asked to
provide the spinning reserve, i.e overloading of generators. Since
many wind turbines had practically no overload capability, some were
tripped more or less immediately before the emergency gas turbines had
been started. With loss of some wind turbine production the remaining
capacity was asked to produce more overload power. More and more wind
turbines overloaded and tripped. The wind turbine tripping rippled
through the network.

Interesting. Can you provide a resource that talks about this? When exactly was this event? I'm surprised the grid can "ask" a generator to supply any given amount of power. I thought an inverter connected supplier would just provide what it can and that's all. Inverters are normally designed to track the frequency and voltage of the grid. I'm not sure how the grid would "ask" the supplier to provide more power.

--

Rick C.

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

 

[Bill Sloman]

On Sunday, August 11, 2019 at 4:10:45 PM UTC+10, upsid...@downunder.com wrote:

On Sat, 10 Aug 2019 17:17:09 -0700 (PDT), Bill Sloman
bill.sloman@ieee.org> wrote:

On Sunday, August 11, 2019 at 2:03:40 AM UTC+10, upsid...@downunder.com wrote:
On Sat, 10 Aug 2019 13:52:03 +0100, Martin Brown
'''newspam'''@nezumi.demon.co.uk> wrote:

[1] There blackouts across the Midlands, the South East,
South West, North West and north east of England, and
Wales.

It seems likely that the initial problem which was the first gas turbine
generator dropping out wasn't dealt with in the two minutes before a
second independent failure of a wind turbine farm. The two being offline
together then took the mains frequency sufficiently far out of bounds
that some inverters stopped as well. Cascade failure followed.

It also may be that they had a bit bad luck.

Good network management requires that the N-1 rule is followed. The
network should survive the loss of _largest_ production unit. In
practice during the first minutes the spinning reserve of other power
plants are used (.i.e. overloading them). During that time quick
start emergency gas turbines are started, which then takes over from
the spinning reserve. When the emergency gas turbines are running, the
power of existing power plants are added e.g. by burning more coal to
get more steam or other slower starting power plants are starting.
When these are running, the emergency gas turbines can be shut down
and the N-1 criterion is restored, waiting for the loss of the next
largest production unit. These emergency gas turbines are typically
running for less than an hour.

However, as long as the emergency gas turbines are used, the network
doesn't tolerate the loss of the next largest unit.

When South Australia bought its big Telsa battery, with the fast inverter built in, it more or less immediately demonstrated the convience of having a really fast-acting voltage and frequency correcting device.

https://reneweconomy.com.au/how-the-tesla-big-battery-kept-the-lights-on-in-south-australia-20393/

Dinowig is fast, but not that fast.

snip

Originally the idea with the N-1 rule was that after the failure of
the largest production unit, the remaining production units can be
slightly overloaded for a while until new production capacity has ben
dispatched (spinning reserve).

This assumption is true with _BIG_ synchronous generators with can be
overloaded by 5 - 10 % for a minute or two without overheating too
much. Thus if a 1000 MW unit is lost the total grid on-line capacity
needs to be 10-20 GW, each of which can be overloaded by 5 - 10 %,

After this minute or two, fast starting emergency gas turbines or
diesels must be running so that the big generators can be scaled down
to nominal capacity.

However, a lot of renewable sources are inverter connected. These
inverters have no overload capacity or at most a few second capability
before overheating.

The inverters have to be designed to take the maximum output the source can generate indefinitely. They won't designed down to this limit, but rather designed to use the components which can offer this, as opposed to the next size down, which couldn't.

The renewable sources aren't normally going to operate at this limit (because there will be a cloud in the sky, or merely average wind speeds).

This strikes me as a nonsense argument.

About a decade ago there was a huge wind energy boom in Germany due to
ample subsidies, so that every farmer wanted a wind turbine on their
field, no matter how bad the wind conditions are. These could also
sell all production to the net, this running at 100 % load as long as
there is wind.

In a fault condition. when all remaining production were asked to
provide the spinning reserve, i.e overloading of generators. Since
many wind turbines had practically no overload capability, some were
tripped more or less immediately before the emergency gas turbines had
been started.

So they weren't designed right.

With loss of some wind turbine production the remaining
capacity was asked to produce more overload power. More and more wind
turbines overloaded and tripped. The wind turbine tripping rippled
through the network.

One example of bad desing in an early adopters system isn't evidence of a fundamental flaw in the concept.

There are at least two solutions to this problem.

1.) Allow inverter based system to generate only 90 % of rated power
on a day to day bases, thus when asked to provide the spinning
reserve equivalence, the output can be increased to 100 %, which
doesn't cause overload tripping. Greens would cry loudly foul, when
they are not able to sell all their production at all time.

What kind of renewable system would spend much time generating its maximum output?

2.) Provide a battery backup system as in Fairbanks Alaska or South
Australia. The combined output power from these units should be as
big as the largest unit in the network, say 1000 MW. The batteries
should be able to provide that power for a few minutes (replacing
spinning reserve) before emergency gas turbines have started. If the
combined battery is sufficiently large, say 1000 MWh, it could also
replace the emergency gas turbines.

http://theconversation.com/yes-sas-battery-is-a-massive-battery-but-it-can-do-much-more-besides-88480

The South Australian system had a 100 MW output capacity and could store 129 MW.hour, or about 2.5 minutes of network load.

That turned out to be plenty - pretty much as soons as it was installed it let the South Australian network keep running through a generator failure that knocked out two adjecent networks to which it was linked.

In practice it has taken over the business of dealing with short term phase and voltage deviations, and earned enough do that to pay off the purchase price in the first year or so of operation.

Anyway the cost of either of these methods should be included in the
cost of renewable sources.

The South Australian battery makes additional money - not as much but enoungh to cover the interest on the purchase price - by buying up power when it is cheap and storing it in the battery, and selling it off again at a higher price when the price of power has been bid up by the regular suppliers.

The free market - and the grid power auction system - makes the battery a profit centre, rather than a cost.

Every properly designed power system should have one. Pumped water storage is quickish, but it take a minute or two for the water in the pipes feeding the turbines to accelerate after the sluice gatres have been opened up. Battery plus inverter is a lot quicker.

--
Bill Sloman, Sydney

 

On Sat, 10 Aug 2019 23:35:47 -0700 (PDT), Rick C
<gnuarm.deletethisbit@gmail.com> wrote:

On Sunday, August 11, 2019 at 2:10:45 AM UTC-4, upsid...@downunder.com wrote:
On Sat, 10 Aug 2019 17:17:09 -0700 (PDT), Bill Sloman
bill.sloman@ieee.org> wrote:

On Sunday, August 11, 2019 at 2:03:40 AM UTC+10, upsid...@downunder.com wrote:
On Sat, 10 Aug 2019 13:52:03 +0100, Martin Brown
'''newspam'''@nezumi.demon.co.uk> wrote:

[1] There blackouts across the Midlands, the South East,
South West, North West and north east of England, and
Wales.

It seems likely that the initial problem which was the first gas turbine
generator dropping out wasn't dealt with in the two minutes before a
second independent failure of a wind turbine farm. The two being offline
together then took the mains frequency sufficiently far out of bounds
that some inverters stopped as well. Cascade failure followed.

It also may be that they had a bit bad luck.

Good network management requires that the N-1 rule is followed. The
network should survive the loss of _largest_ production unit. In
practice during the first minutes the spinning reserve of other power
plants are used (.i.e. overloading them). During that time quick
start emergency gas turbines are started, which then takes over from
the spinning reserve. When the emergency gas turbines are running, the
power of existing power plants are added e.g. by burning more coal to
get more steam or other slower starting power plants are starting.
When these are running, the emergency gas turbines can be shut down
and the N-1 criterion is restored, waiting for the loss of the next
largest production unit. These emergency gas turbines are typically
running for less than an hour.

However, as long as the emergency gas turbines are used, the network
doesn't tolerate the loss of the next largest unit.

When South Australia bought its big Telsa battery, with the fast inverter built in, it more or less immediately demonstrated the convience of having a really fast-acting voltage and frequency correcting device.

https://reneweconomy.com.au/how-the-tesla-big-battery-kept-the-lights-on-in-south-australia-20393/

Dinowig is fast, but not that fast.

snip

Originally the idea with the N-1 rule was that after the failure of
the largest production unit, the remaining production units can be
slightly overloaded for a while until new production capacity has ben
dispatched (spinning reserve).

This assumption is true with _BIG_ synchronous generators with can be
overloaded by 5 - 10 % for a minute or two without overheating too
much. Thus if a 1000 MW unit is lost the total grid on-line capacity
needs to be 10-20 GW, each of which can be overloaded by 5 - 10 %,

After this minute or two, fast starting emergency gas turbines or
diesels must be running so that the big generators can be scaled down
to nominal capacity.

However, a lot of renewable sources are inverter connected. These
inverters have no overload capacity or at most a few second capability
before overheating.

About a decade ago there was a huge wind energy boom in Germany due to
ample subsidies, so that every farmer wanted a wind turbine on their
field, no matter how bad the wind conditions are. These could also
sell all production to the net, this running at 100 % load as long as
there is wind.

In a fault condition. when all remaining production were asked to
provide the spinning reserve, i.e overloading of generators. Since
many wind turbines had practically no overload capability, some were
tripped more or less immediately before the emergency gas turbines had
been started. With loss of some wind turbine production the remaining
capacity was asked to produce more overload power. More and more wind
turbines overloaded and tripped. The wind turbine tripping rippled
through the network.

Interesting. Can you provide a resource that talks about this? When exactly was this event?

Just do a search for

"N-1" "wind turbine"

added with keywords like trip, fault or overload. This should return
quite a lot hits from a long period of time, indicating that the
limited overload capability of wind turbine and other renewable
sources are a significant issue.


>I'm surprised the grid can "ask" a generator to supply any given amount of power. I thought an inverter connected supplier would just provide what it can and that's all. Inverters are normally designed to track the frequency and voltage of the grid. I'm not sure how the grid would "ask" the supplier to provide more power.

Sorry, wrong verb, i should have said "demand".

Assume that in an AC network (without any network control) there are
multiple generators and multiple loads. In the beginning, the
production and demand must be in balance.

Assume that one generator is lost, while the loads still demand the
same power. In this situation, the remaining generators must still
provide the same load demand. This can be done by overloading the
remaining generators, shredding some loads or let the AC network
collapse.

 

[Rick C]

On Sunday, August 11, 2019 at 10:10:38 AM UTC-4, upsid...@downunder.com wrote:

On Sat, 10 Aug 2019 23:35:47 -0700 (PDT), Rick C
gnuarm.deletethisbit@gmail.com> wrote:

On Sunday, August 11, 2019 at 2:10:45 AM UTC-4, upsid...@downunder.com wrote:
On Sat, 10 Aug 2019 17:17:09 -0700 (PDT), Bill Sloman
bill.sloman@ieee.org> wrote:

On Sunday, August 11, 2019 at 2:03:40 AM UTC+10, upsid...@downunder.com wrote:
On Sat, 10 Aug 2019 13:52:03 +0100, Martin Brown
'''newspam'''@nezumi.demon.co.uk> wrote:

[1] There blackouts across the Midlands, the South East,
South West, North West and north east of England, and
Wales.

It seems likely that the initial problem which was the first gas turbine
generator dropping out wasn't dealt with in the two minutes before a
second independent failure of a wind turbine farm. The two being offline
together then took the mains frequency sufficiently far out of bounds
that some inverters stopped as well. Cascade failure followed.

It also may be that they had a bit bad luck.

Good network management requires that the N-1 rule is followed. The
network should survive the loss of _largest_ production unit. In
practice during the first minutes the spinning reserve of other power
plants are used (.i.e. overloading them). During that time quick
start emergency gas turbines are started, which then takes over from
the spinning reserve. When the emergency gas turbines are running, the
power of existing power plants are added e.g. by burning more coal to
get more steam or other slower starting power plants are starting.
When these are running, the emergency gas turbines can be shut down
and the N-1 criterion is restored, waiting for the loss of the next
largest production unit. These emergency gas turbines are typically
running for less than an hour.

However, as long as the emergency gas turbines are used, the network
doesn't tolerate the loss of the next largest unit.

When South Australia bought its big Telsa battery, with the fast inverter built in, it more or less immediately demonstrated the convience of having a really fast-acting voltage and frequency correcting device.

https://reneweconomy.com.au/how-the-tesla-big-battery-kept-the-lights-on-in-south-australia-20393/

Dinowig is fast, but not that fast.

snip

Originally the idea with the N-1 rule was that after the failure of
the largest production unit, the remaining production units can be
slightly overloaded for a while until new production capacity has ben
dispatched (spinning reserve).

This assumption is true with _BIG_ synchronous generators with can be
overloaded by 5 - 10 % for a minute or two without overheating too
much. Thus if a 1000 MW unit is lost the total grid on-line capacity
needs to be 10-20 GW, each of which can be overloaded by 5 - 10 %,

After this minute or two, fast starting emergency gas turbines or
diesels must be running so that the big generators can be scaled down
to nominal capacity.

However, a lot of renewable sources are inverter connected. These
inverters have no overload capacity or at most a few second capability
before overheating.

About a decade ago there was a huge wind energy boom in Germany due to
ample subsidies, so that every farmer wanted a wind turbine on their
field, no matter how bad the wind conditions are. These could also
sell all production to the net, this running at 100 % load as long as
there is wind.

In a fault condition. when all remaining production were asked to
provide the spinning reserve, i.e overloading of generators. Since
many wind turbines had practically no overload capability, some were
tripped more or less immediately before the emergency gas turbines had
been started. With loss of some wind turbine production the remaining
capacity was asked to produce more overload power. More and more wind
turbines overloaded and tripped. The wind turbine tripping rippled
through the network.

Interesting. Can you provide a resource that talks about this? When exactly was this event?

Just do a search for

"N-1" "wind turbine"

added with keywords like trip, fault or overload. This should return
quite a lot hits from a long period of time, indicating that the
limited overload capability of wind turbine and other renewable
sources are a significant issue.


I'm surprised the grid can "ask" a generator to supply any given amount of power. I thought an inverter connected supplier would just provide what it can and that's all. Inverters are normally designed to track the frequency and voltage of the grid. I'm not sure how the grid would "ask" the supplier to provide more power.

Sorry, wrong verb, i should have said "demand".

Assume that in an AC network (without any network control) there are
multiple generators and multiple loads. In the beginning, the
production and demand must be in balance.

Assume that one generator is lost, while the loads still demand the
same power. In this situation, the remaining generators must still
provide the same load demand. This can be done by overloading the
remaining generators, shredding some loads or let the AC network
collapse.

Lol! Loads don't demand power. Just like the frequency, if the loads remain the same (which is impedance, not current) the voltage and current will drop when supply is decreased. The voltage and current will continue to drop as the inertia of the generators is turned into work eventually reaching a steady state when the power to the loads equals the generation power.

That is... unless failure sensing decides to shut down generation or take loads off line. That is when things go haywire.

--

Rick C.

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

 

On Sun, 11 Aug 2019 05:03:58 -0700 (PDT), Bill Sloman
<bill.sloman@ieee.org> wrote:

However, a lot of renewable sources are inverter connected. These
inverters have no overload capacity or at most a few second capability
before overheating.

The inverters have to be designed to take the maximum output the source can generate indefinitely. They won't designed down to this limit, but rather designed to use the components which can offer this, as opposed to the next size down, which couldn't.

The renewable sources aren't normally going to operate at this limit (because there will be a cloud in the sky, or merely average wind speeds).

This strikes me as a nonsense argument.

Both solar as well as wind power have a well defined maximum (100 %).

The solar radiation on a clear day is quite close to 1000 W/m˛,
Depending on solar panel efficiency this translates to 100-150 W/m˛.

If we look at the wind turbine output power vs. wind speed, at low
wind speeds the maximum available power is proportional to the cube of
wind speed. At a certain wind speed, say 5 m/s and above, the output
power is limited by the generator size. It remains at this constant
level (100 %) up to stormy winds around 20 or 25 m/s, when the turbine
must be stopped to avoid permanent damage. Variable pitch propellers
can be used to limit the axial power and also in older turbines, the
blade profile was such that part of the blade stalled at high winds.

In reality the output power is determined by the selection of the
generator ratings. After that, the only significant parameter that can
be varied is the propeller diameter. By selecting a big propeller, the
nominal power is achieved at 5 m/s, but a smaller power and lower
tower, up to 7 m/s is required for nominal output.

One tries to select the propeller size according to prevailing winds
on a particular site. You try to select so the size that the wind is
in the constant power most of the time.

The COP depends also on the prevailing winds and propeller diameter
vs. generator nominal power.

One tries to avoid to operate in the say 2.5 to 5 m/s speed range, in
which the generated power would vary 8 times from 12.5 % to 100 %.

 

[Cursitor Doom]

On Sun, 11 Aug 2019 08:27:57 -0700, Rick C wrote:

That is... unless failure sensing decides to shut down generation or
take loads off line. That is when things go haywire.

https://www.originenergy.com.au/blog/about-energy/load-shedding.html?
PageSpeed=noscript



--
This message may be freely reproduced without limit or charge only via
the Usenet protocol. Reproduction in whole or part through other
protocols, whether for profit or not, is conditional upon a charge of
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protocols constitutes acceptance of this condition.

 

[Bill Sloman]

On Monday, August 12, 2019 at 12:10:38 AM UTC+10, upsid...@downunder.com wrote:

On Sat, 10 Aug 2019 23:35:47 -0700 (PDT), Rick C
gnuarm.deletethisbit@gmail.com> wrote:
On Sunday, August 11, 2019 at 2:10:45 AM UTC-4, upsid...@downunder.com wrote:
On Sat, 10 Aug 2019 17:17:09 -0700 (PDT), Bill Sloman
bill.sloman@ieee.org> wrote:
On Sunday, August 11, 2019 at 2:03:40 AM UTC+10, upsid...@downunder.com wrote:
On Sat, 10 Aug 2019 13:52:03 +0100, Martin Brown
'''newspam'''@nezumi.demon.co.uk> wrote:

<snip>

When South Australia bought its big Telsa battery, with the fast inverter built in, it more or less immediately demonstrated the convience of having a really fast-acting voltage and frequency correcting device.

https://reneweconomy.com.au/how-the-tesla-big-battery-kept-the-lights-on-in-south-australia-20393/

Dinowig is fast, but not that fast.

snip

Originally the idea with the N-1 rule was that after the failure of
the largest production unit, the remaining production units can be
slightly overloaded for a while until new production capacity has ben
dispatched (spinning reserve).

This assumption is true with _BIG_ synchronous generators with can be
overloaded by 5 - 10 % for a minute or two without overheating too
much. Thus if a 1000 MW unit is lost the total grid on-line capacity
needs to be 10-20 GW, each of which can be overloaded by 5 - 10 %,

After this minute or two, fast starting emergency gas turbines or
diesels must be running so that the big generators can be scaled down
to nominal capacity.

However, a lot of renewable sources are inverter connected. These
inverters have no overload capacity or at most a few second capability
before overheating.

About a decade ago there was a huge wind energy boom in Germany due to
ample subsidies, so that every farmer wanted a wind turbine on their
field, no matter how bad the wind conditions are. These could also
sell all production to the net, this running at 100 % load as long as
there is wind.

In a fault condition. when all remaining production were asked to
provide the spinning reserve, i.e overloading of generators. Since
many wind turbines had practically no overload capability, some were
tripped more or less immediately before the emergency gas turbines had
been started. With loss of some wind turbine production the remaining
capacity was asked to produce more overload power. More and more wind
turbines overloaded and tripped. The wind turbine tripping rippled
through the network.

Interesting. Can you provide a resource that talks about this? When exactly was this event?

Just do a search for

"N-1" "wind turbine"

added with keywords like trip, fault or overload. This should return
quite a lot hits from a long period of time, indicating that the
limited overload capability of wind turbine and other renewable
sources are a significant issue.


I'm surprised the grid can "ask" a generator to supply any given amount of power. I thought an inverter connected supplier would just provide what it can and that's all. Inverters are normally designed to track the frequency and voltage of the grid. I'm not sure how the grid would "ask" the supplier to provide more power.

Sorry, wrong verb, i should have said "demand".

Assume that in an AC network (without any network control) there are
multiple generators and multiple loads. In the beginning, the
production and demand must be in balance.

Assume that one generator is lost, while the loads still demand the
same power. In this situation, the remaining generators must still
provide the same load demand. This can be done by overloading the
remaining generators, shredding some loads or let the AC network
collapse.

Or having a fast acting short term backup - as the Telsa battery in South Australia demonstrated.

So Germany put in a lot of fragile wind generators without putting in the battery back-up that they turned out to need?

Early adopters have these kinds of problems.

--
Bill Sloman, Sydney

 

[Bill Sloman]

On Sunday, August 11, 2019 at 4:10:45 PM UTC+10, upsid...@downunder.com wrote:

On Sat, 10 Aug 2019 17:17:09 -0700 (PDT), Bill Sloman
bill.sloman@ieee.org> wrote:

On Sunday, August 11, 2019 at 2:03:40 AM UTC+10, upsid...@downunder.com wrote:
On Sat, 10 Aug 2019 13:52:03 +0100, Martin Brown
'''newspam'''@nezumi.demon.co.uk> wrote:

[1] There blackouts across the Midlands, the South East,
South West, North West and north east of England, and
Wales.

It seems likely that the initial problem which was the first gas turbine
generator dropping out wasn't dealt with in the two minutes before a
second independent failure of a wind turbine farm. The two being offline
together then took the mains frequency sufficiently far out of bounds
that some inverters stopped as well. Cascade failure followed.

It also may be that they had a bit bad luck.

Good network management requires that the N-1 rule is followed. The
network should survive the loss of _largest_ production unit. In
practice during the first minutes the spinning reserve of other power
plants are used (.i.e. overloading them). During that time quick
start emergency gas turbines are started, which then takes over from
the spinning reserve. When the emergency gas turbines are running, the
power of existing power plants are added e.g. by burning more coal to
get more steam or other slower starting power plants are starting.
When these are running, the emergency gas turbines can be shut down
and the N-1 criterion is restored, waiting for the loss of the next
largest production unit. These emergency gas turbines are typically
running for less than an hour.

However, as long as the emergency gas turbines are used, the network
doesn't tolerate the loss of the next largest unit.

When South Australia bought its big Telsa battery, with the fast inverter built in, it more or less immediately demonstrated the convience of having a really fast-acting voltage and frequency correcting device.

https://reneweconomy.com.au/how-the-tesla-big-battery-kept-the-lights-on-in-south-australia-20393/

Dinowig is fast, but not that fast.

snip

Originally the idea with the N-1 rule was that after the failure of
the largest production unit, the remaining production units can be
slightly overloaded for a while until new production capacity has ben
dispatched (spinning reserve).

This assumption is true with _BIG_ synchronous generators with can be
overloaded by 5 - 10 % for a minute or two without overheating too
much. Thus if a 1000 MW unit is lost the total grid on-line capacity
needs to be 10-20 GW, each of which can be overloaded by 5 - 10 %,

After this minute or two, fast starting emergency gas turbines or
diesels must be running so that the big generators can be scaled down
to nominal capacity.

However, a lot of renewable sources are inverter connected. These
inverters have no overload capacity or at most a few second capability
before overheating.

There is a fallacy here. The inverters aren't the expensive part of the installation, and could be over-sized for very little extra money. The rotating machinery is expensive, but it is essentially the same kind of hardware that you find in conventional generators, and have the same kind of thermal time constants which would allow them to push out extra current for a minute or two.

About a decade ago there was a huge wind energy boom in Germany due to
ample subsidies, so that every farmer wanted a wind turbine on their
field, no matter how bad the wind conditions are. These could also
sell all production to the net, this running at 100 % load as long as
there is wind.

In a fault condition. when all remaining production were asked to
provide the spinning reserve, i.e overloading of generators. Since
many wind turbines had practically no overload capability, some were
tripped more or less immediately before the emergency gas turbines had
been started. With loss of some wind turbine production the remaining
capacity was asked to produce more overload power. More and more wind
turbines overloaded and tripped. The wind turbine tripping rippled
through the network.

There are at least two solutions to this problem.

1.) Allow inverter based system to generate only 90 % of rated power
on a day to day bases, thus when asked to provide the spinning
reserve equivalence, the output can be increased to 100 %, which
doesn't cause overload tripping. Greens would cry loudly foul, when
they are not able to sell all their production at all time.

Actually, this solution involves up-grading the inverter electronics to handle the extra 10% power for the few minutes that it would take for the windings in the rotor to get dangerously warm. The inverter electronics are a lot cheaper than the copper and iron. Retrofitting better electronics probably wouldn't be difficult or expensive.

<snip - battery back-up is the no-brainer solution, in part because it solves other problems in grid regulation, and shouldn't be seen as a additional expense>

--
Bill Sloman, Sydney

 

[Martin Brown]

On 12/08/2019 01:01, Bill Sloman wrote:

On Sunday, August 11, 2019 at 4:10:45 PM UTC+10,
upsid...@downunder.com wrote:
On Sat, 10 Aug 2019 17:17:09 -0700 (PDT), Bill Sloman
bill.sloman@ieee.org> wrote:

When South Australia bought its big Telsa battery, with the fast
inverter built in, it more or less immediately demonstrated the
convience of having a really fast-acting voltage and frequency
correcting device.

https://reneweconomy.com.au/how-the-tesla-big-battery-kept-the-lights-on-in-south-australia-20393/


Dinowig is fast, but not that fast.

snip

Originally the idea with the N-1 rule was that after the failure
of the largest production unit, the remaining production units can
be slightly overloaded for a while until new production capacity
has ben dispatched (spinning reserve).

This assumption is true with _BIG_ synchronous generators with can
be overloaded by 5 - 10 % for a minute or two without overheating
too much. Thus if a 1000 MW unit is lost the total grid on-line
capacity needs to be 10-20 GW, each of which can be overloaded by 5
- 10 %,

After this minute or two, fast starting emergency gas turbines or
diesels must be running so that the big generators can be scaled
down to nominal capacity.

However, a lot of renewable sources are inverter connected. These
inverters have no overload capacity or at most a few second
capability before overheating.

There is a fallacy here. The inverters aren't the expensive part of
the installation, and could be over-sized for very little extra

Although they could be you can't ask the wind to blow harder because the
grid is under threat so wind farms can only supply what is available at
that instant and no more. Something else has to take up the slack.

Perhaps having battery storage co-located with the wind farms so that
when the chips are down their inverters can be run at their full rated
power to smooth things out would make sense. Most times I would guess
the inverter has at least 50% of its rated capacity unused. Only when
the wind speed is typically 14m/s or more is it running flat out.

The other problem is that since output from a windfarm scales with the
cube of the wind velocity you would be adding cost to the inverters for
an incredibly rare use case - basically in a storm just before you need
to start feathering the blades to stop them from spinning over speed.

money. The rotating machinery is expensive, but it is essentially the
same kind of hardware that you find in conventional generators, and
have the same kind of thermal time constants which would allow them
to push out extra current for a minute or two.

I don't see why the wind farms *have* to drop off though. They can
surely continue to support the other generators with their basically
fixed power output even if the frequency drifts by more than 1 Hz low
but at a lower voltage and slightly higher current. It was a control
loop decision for them to drop off grid for frequency deviation.

They could also borrow a bit of kinetic energy from the spinning rotor
blades in the very short term. Except in storm conditions there should
always be enough reserve in the inverters to cope with the "overload".

What has become clear is that there is a lot of kit in the UK that
assumes continuous mains power as a given and does not recover at all
gracefully when there is a power cut. The railway signalling system and
one entire class of locomotives required a full engineering reset by
technicians on site before they could be restarted or used again. This
isn't so easy when the train is stuck on some remote stretch of track!

WTF they dropped the railways signalling system off grid is unclear. I
can see the point of dropping the trains since they are a decent sized
bulk load and there are hardly any electric arc furnaces or aluminium
smelters left now. ISTR of the intermittent fast balancing load dumps
only the big chlor-alkali electrolytic cells at Runcorn remain.

It is amazing just how much damage a 15 minute power cut at rush hour
was able to do to the UK infrastructure. Well done National Grid!

--
Regards,
Martin Brown

 

[Rick C]

On Tuesday, August 13, 2019 at 2:35:50 AM UTC-4, Sylvia Else wrote:

On 4/08/2019 2:44 am, Rick C wrote:
On Saturday, August 3, 2019 at 12:41:00 PM UTC-4, John Larkin wrote:
On Sat, 3 Aug 2019 17:15:00 +0100, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 03/08/19 16:44, John Larkin wrote:
On Sat, 3 Aug 2019 14:40:47 -0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

Worth a try!

https://tinyurl.com/y67eltrh

What will we do with gigawatts of power that peaks mid-day, only on
good days?

If you have hills and water, push the water uphill.

Well, we do have some hills sixty miles away from the central valley.
I doubt that mass energy storage is economical; certainly batteries
aren't.

Solar makes little sense; natural gas fracking is in financial trouble
in the US because it has been so successful that there's a glut of
cheap gas. If we have to build NG plants to power us up when the sun
don't shine, may as well run them 24/7.

Except the cost of solar is currently competitive and still dropping. Why pay more for energy from a harmful source? Do you just like to toss money out the window?


It isn't really competitive, it's just benefiting from a market that's
been seriously distorted by political considerations.

Try selling any other commodity on the basis that you'll supply it when
it's convenient to you, and not otherwise.

That's exactly what I do. My customer sends me a PO and I let them know when they can have the boards. In the past I have pushed to try to deliver on their schedule, but it is never good enough and they often want earlier delivery even after I accept the PO. I stopped worrying about it and now they get the boards when I tell them they can have them.

--

Rick C.

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

 

[Sylvia Else]

On 4/08/2019 2:44 am, Rick C wrote:

On Saturday, August 3, 2019 at 12:41:00 PM UTC-4, John Larkin wrote:
On Sat, 3 Aug 2019 17:15:00 +0100, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 03/08/19 16:44, John Larkin wrote:
On Sat, 3 Aug 2019 14:40:47 -0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

Worth a try!

https://tinyurl.com/y67eltrh

What will we do with gigawatts of power that peaks mid-day, only on
good days?

If you have hills and water, push the water uphill.

Well, we do have some hills sixty miles away from the central valley.
I doubt that mass energy storage is economical; certainly batteries
aren't.

Solar makes little sense; natural gas fracking is in financial trouble
in the US because it has been so successful that there's a glut of
cheap gas. If we have to build NG plants to power us up when the sun
don't shine, may as well run them 24/7.

Except the cost of solar is currently competitive and still dropping. Why pay more for energy from a harmful source? Do you just like to toss money out the window?

It isn't really competitive, it's just benefiting from a market that's
been seriously distorted by political considerations.

Try selling any other commodity on the basis that you'll supply it when
it's convenient to you, and not otherwise.

Sylvia.

 

On Sun, 11 Aug 2019 17:01:59 -0700 (PDT), Bill Sloman
<bill.sloman@ieee.org> wrote:

On Sunday, August 11, 2019 at 4:10:45 PM UTC+10, upsid...@downunder.com wrote:
On Sat, 10 Aug 2019 17:17:09 -0700 (PDT), Bill Sloman
bill.sloman@ieee.org> wrote:

On Sunday, August 11, 2019 at 2:03:40 AM UTC+10, upsid...@downunder.com wrote:
On Sat, 10 Aug 2019 13:52:03 +0100, Martin Brown
'''newspam'''@nezumi.demon.co.uk> wrote:

[1] There blackouts across the Midlands, the South East,
South West, North West and north east of England, and
Wales.

It seems likely that the initial problem which was the first gas turbine
generator dropping out wasn't dealt with in the two minutes before a
second independent failure of a wind turbine farm. The two being offline
together then took the mains frequency sufficiently far out of bounds
that some inverters stopped as well. Cascade failure followed.

It also may be that they had a bit bad luck.

Good network management requires that the N-1 rule is followed. The
network should survive the loss of _largest_ production unit. In
practice during the first minutes the spinning reserve of other power
plants are used (.i.e. overloading them). During that time quick
start emergency gas turbines are started, which then takes over from
the spinning reserve. When the emergency gas turbines are running, the
power of existing power plants are added e.g. by burning more coal to
get more steam or other slower starting power plants are starting.
When these are running, the emergency gas turbines can be shut down
and the N-1 criterion is restored, waiting for the loss of the next
largest production unit. These emergency gas turbines are typically
running for less than an hour.

However, as long as the emergency gas turbines are used, the network
doesn't tolerate the loss of the next largest unit.

When South Australia bought its big Telsa battery, with the fast inverter built in, it more or less immediately demonstrated the convience of having a really fast-acting voltage and frequency correcting device.

https://reneweconomy.com.au/how-the-tesla-big-battery-kept-the-lights-on-in-south-australia-20393/

Dinowig is fast, but not that fast.

snip

Originally the idea with the N-1 rule was that after the failure of
the largest production unit, the remaining production units can be
slightly overloaded for a while until new production capacity has ben
dispatched (spinning reserve).

This assumption is true with _BIG_ synchronous generators with can be
overloaded by 5 - 10 % for a minute or two without overheating too
much. Thus if a 1000 MW unit is lost the total grid on-line capacity
needs to be 10-20 GW, each of which can be overloaded by 5 - 10 %,

After this minute or two, fast starting emergency gas turbines or
diesels must be running so that the big generators can be scaled down
to nominal capacity.

However, a lot of renewable sources are inverter connected. These
inverters have no overload capacity or at most a few second capability
before overheating.

There is a fallacy here. The inverters aren't the expensive part of the installation, and could be over-sized for very little extra money. The rotating machinery is expensive, but it is essentially the same kind of hardware that you find in conventional generators, and have the same kind of thermal time constants which would allow them to push out extra current for a minute or two.

Are you sure that a small 3 MW wind generator and power plant size 300
MW generator have the same thermal time constant ?

 

[Sylvia Else]

On 13/08/2019 4:42 pm, Rick C wrote:

On Tuesday, August 13, 2019 at 2:35:50 AM UTC-4, Sylvia Else wrote:
On 4/08/2019 2:44 am, Rick C wrote:
On Saturday, August 3, 2019 at 12:41:00 PM UTC-4, John Larkin
wrote:
On Sat, 3 Aug 2019 17:15:00 +0100, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 03/08/19 16:44, John Larkin wrote:
On Sat, 3 Aug 2019 14:40:47 -0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

Worth a try!

https://tinyurl.com/y67eltrh

What will we do with gigawatts of power that peaks mid-day,
only on good days?

If you have hills and water, push the water uphill.

Well, we do have some hills sixty miles away from the central
valley. I doubt that mass energy storage is economical;
certainly batteries aren't.

Solar makes little sense; natural gas fracking is in financial
trouble in the US because it has been so successful that
there's a glut of cheap gas. If we have to build NG plants to
power us up when the sun don't shine, may as well run them
24/7.

Except the cost of solar is currently competitive and still
dropping. Why pay more for energy from a harmful source? Do you
just like to toss money out the window?


It isn't really competitive, it's just benefiting from a market
that's been seriously distorted by political considerations.

Try selling any other commodity on the basis that you'll supply it
when it's convenient to you, and not otherwise.

That's exactly what I do. My customer sends me a PO and I let them
know when they can have the boards. In the past I have pushed to try
to deliver on their schedule, but it is never good enough and they
often want earlier delivery even after I accept the PO. I stopped
worrying about it and now they get the boards when I tell them they
can have them.

Your boards are hardly a commodity.

Sylvia.

 

[Rick C]

On Tuesday, August 13, 2019 at 2:49:53 AM UTC-4, Sylvia Else wrote:

On 4/08/2019 1:44 am, John Larkin wrote:
On Sat, 3 Aug 2019 14:40:47 -0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

Worth a try!

https://tinyurl.com/y67eltrh

What will we do with gigawatts of power that peaks mid-day, only on
good days?



I'm waiting for the day when solar routines displaces all the fossil
fuel generation, and owners discover that when all the remaining
generation has a zero marginal cost of generation, the market price
collapses.

At the same time the greenies will finally realise that they cannot
build any more solar farms, because there's no use for the power they
generate, but the zero-carbon future still hasn't been reached, because
of all the fossil fuel generation during the large part of day when
solar doesn't produce.

Then the politicians will discover that nuclear power isn't so bad after
all.

Nuclear isn't "bad" (except for the waste issue) it's just expensive. The North Anna reactor Dominion has received approval for will cost $19 billion! That's $0.06 per kW just for the capital without counting the interest, operation, refueling, etc... and not counting the cost of waste handling.

How much are you willing to pay for using nuclear?

Then you seem to ignore the potential for storing energy to make renewable energy available 24/7. The UK has at least 1400 MW of pumped storage hydro for a country that uses about 30 or 40 GW peak. Obviously it can't be so expensive.

--

Rick C.

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

 

[Rick C]

On Tuesday, August 13, 2019 at 2:44:34 AM UTC-4, Sylvia Else wrote:

On 13/08/2019 4:42 pm, Rick C wrote:
On Tuesday, August 13, 2019 at 2:35:50 AM UTC-4, Sylvia Else wrote:

It isn't really competitive, it's just benefiting from a market
that's been seriously distorted by political considerations.

Try selling any other commodity on the basis that you'll supply it
when it's convenient to you, and not otherwise.

That's exactly what I do. My customer sends me a PO and I let them
know when they can have the boards. In the past I have pushed to try
to deliver on their schedule, but it is never good enough and they
often want earlier delivery even after I accept the PO. I stopped
worrying about it and now they get the boards when I tell them they
can have them.


Your boards are hardly a commodity.

In some ways they are. The customer actually owns the design. But for them to make these themselves they would have to spend money to put them into production, develop testing, etc. So they go with the lower cost option even though they can't have them just when they want them. Same with power.

Besides, it's a false issue. Currently we can avoid releasing carbon by replacing fossil fuel with renewables. The cost is less than the other choices, especially nuclear. As the price drops further it will be economical to use storage with even more renewable energy.

I was surprised to learn that in the UK wind power is on par with nuclear capacity and at times equals CCGT (gas) usage. They also have significant amount of "biomass" generation. Not sure what that is, I guess making gas from plants and burning that?

--

Rick C.

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

 

[Sylvia Else]

On 4/08/2019 1:44 am, John Larkin wrote:

On Sat, 3 Aug 2019 14:40:47 -0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

Worth a try!

https://tinyurl.com/y67eltrh

What will we do with gigawatts of power that peaks mid-day, only on
good days?

I'm waiting for the day when solar routines displaces all the fossil
fuel generation, and owners discover that when all the remaining
generation has a zero marginal cost of generation, the market price
collapses.

At the same time the greenies will finally realise that they cannot
build any more solar farms, because there's no use for the power they
generate, but the zero-carbon future still hasn't been reached, because
of all the fossil fuel generation during the large part of day when
solar doesn't produce.

Then the politicians will discover that nuclear power isn't so bad after
all.

Sylvia.

 

[Tom Gardner]

On 13/08/19 08:06, Rick C wrote:

On Tuesday, August 13, 2019 at 2:49:53 AM UTC-4, Sylvia Else wrote:
On 4/08/2019 1:44 am, John Larkin wrote:
On Sat, 3 Aug 2019 14:40:47 -0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

Worth a try!

https://tinyurl.com/y67eltrh

What will we do with gigawatts of power that peaks mid-day, only on good
days?



I'm waiting for the day when solar routines displaces all the fossil fuel
generation, and owners discover that when all the remaining generation has
a zero marginal cost of generation, the market price collapses.

At the same time the greenies will finally realise that they cannot build
any more solar farms, because there's no use for the power they generate,
but the zero-carbon future still hasn't been reached, because of all the
fossil fuel generation during the large part of day when solar doesn't
produce.

Then the politicians will discover that nuclear power isn't so bad after
all.

Nuclear isn't "bad" (except for the waste issue) it's just expensive. The
North Anna reactor Dominion has received approval for will cost $19 billion!
That's $0.06 per kW just for the capital without counting the interest,
operation, refueling, etc... and not counting the cost of waste handling.

How much are you willing to pay for using nuclear?

Then you seem to ignore the potential for storing energy to make renewable
energy available 24/7. The UK has at least 1400 MW of pumped storage hydro
for a country that uses about 30 or 40 GW peak. Obviously it can't be so
expensive.

Sigh. Cherrypicking.

/Surely/ you realise by now that "MW" is only half the story.

The other half is "MWh", and that is sorely lacking in the UK.

 

[Rick C]

On Tuesday, August 13, 2019 at 3:47:31 AM UTC-4, Tom Gardner wrote:

On 13/08/19 08:06, Rick C wrote:
On Tuesday, August 13, 2019 at 2:49:53 AM UTC-4, Sylvia Else wrote:
On 4/08/2019 1:44 am, John Larkin wrote:
On Sat, 3 Aug 2019 14:40:47 -0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

Worth a try!

https://tinyurl.com/y67eltrh

What will we do with gigawatts of power that peaks mid-day, only on good
days?



I'm waiting for the day when solar routines displaces all the fossil fuel
generation, and owners discover that when all the remaining generation has
a zero marginal cost of generation, the market price collapses.

At the same time the greenies will finally realise that they cannot build
any more solar farms, because there's no use for the power they generate,
but the zero-carbon future still hasn't been reached, because of all the
fossil fuel generation during the large part of day when solar doesn't
produce.

Then the politicians will discover that nuclear power isn't so bad after
all.

Nuclear isn't "bad" (except for the waste issue) it's just expensive. The
North Anna reactor Dominion has received approval for will cost $19 billion!
That's $0.06 per kW just for the capital without counting the interest,
operation, refueling, etc... and not counting the cost of waste handling.

How much are you willing to pay for using nuclear?

Then you seem to ignore the potential for storing energy to make renewable
energy available 24/7. The UK has at least 1400 MW of pumped storage hydro
for a country that uses about 30 or 40 GW peak. Obviously it can't be so
expensive.

Sigh. Cherrypicking.

/Surely/ you realise by now that "MW" is only half the story.

The other half is "MWh", and that is sorely lacking in the UK.

Somehow that doesn't surprise me at all. I guess the reservoir is high, but no larger than a bathtub. 10 seconds of backup. How long does CCGT take to come online?

Poor UK.

--

Rick C.

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

 

[piglet]

On 13/08/2019 7:57 am, Rick C wrote:

I was surprised to learn that in the UK wind power is on par with nuclear capacity and at times equals CCGT (gas) usage. They also have significant amount of "biomass" generation. Not sure what that is, I guess making gas from plants and burning that?

Not typically grown explicitly to burn. Biomass is more typically a
bye-product of farming, forestry, landfill and sewage waste. Biogas is
sometimes included within the definition.

piglet

 

[Sylvia Else]

On 13/08/2019 5:06 pm, Rick C wrote:

On Tuesday, August 13, 2019 at 2:49:53 AM UTC-4, Sylvia Else wrote:
On 4/08/2019 1:44 am, John Larkin wrote:
On Sat, 3 Aug 2019 14:40:47 -0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

Worth a try!

https://tinyurl.com/y67eltrh

What will we do with gigawatts of power that peaks mid-day, only
on good days?



I'm waiting for the day when solar routines displaces all the
fossil fuel generation, and owners discover that when all the
remaining generation has a zero marginal cost of generation, the
market price collapses.

At the same time the greenies will finally realise that they
cannot build any more solar farms, because there's no use for the
power they generate, but the zero-carbon future still hasn't been
reached, because of all the fossil fuel generation during the large
part of day when solar doesn't produce.

Then the politicians will discover that nuclear power isn't so bad
after all.

Nuclear isn't "bad" (except for the waste issue) it's just expensive.
The North Anna reactor Dominion has received approval for will cost
$19 billion! That's $0.06 per kW just for the capital without
counting the interest, operation, refueling, etc... and not counting
the cost of waste handling.

How much are you willing to pay for using nuclear?

Then you seem to ignore the potential for storing energy to make
renewable energy available 24/7. The UK has at least 1400 MW of
pumped storage hydro for a country that uses about 30 or 40 GW peak.
Obviously it can't be so expensive.

When used for peak management, it only needs to be cheaper than the
alternative, which is typically gas powered generation.

It's not just the power that matters, it's the energy, and you can't
just build pumped storage anywhere you feel like it - there needs to be
a practical way of storing large quantities of water at two
significantly different levels, or there needs to be a place near the
sea where sea water can be stored at a significantly higher than sea level.

Sylvia