On Thu, 02 May 2013 09:40:07 +0100, The Natural Philosopher wrote:

Frequency is less important now than it was as there are fewer timing
devices rely on it.

Tell that to the German factories running synchronous motors that are
having f to intsall massive UPS/inverters because sudden fluctuations
in the mains frequency due to sun coming out/wind gust coming along are
destroying the machines the motors drive.

So 2 GW can drop off the euro frequency zone and produce a 0.05 Hz change
in the frequnecy but a few wind mills or photo voltaics can shove the
frequency out of spec?

If the factory motors or machinery can't handle within supply
specification frequency variations there is something wrong with them.

Or are you saying, counter to what everyone says, the bit of the Euro
frequency zone in Germany can alter in frequency relative to the rest?

--
Cheers
Dave.

On 02/05/13 09:59, Andy Champ wrote:
On 01/05/2013 13:54, whisky-dave wrote:
Measuring low frequecies accuratly is more difficult than you think.
What you have to do is count cycles in one second yuod get perhaps 47
or 53 so you need to average it out especailly in times of high or
low demand.
So you need to sample it for at least 10 seconds to giove you 0.1
resoultion and in that time the situation can change.

You ought to measure the time for 50 (or something) cycles instead. If
you time it at the zero crossing that doesn't move about much.

Even so - yes, it's hard, especially with a noisy waveform.

don't be silly. an active low pass filter or even a 50hz high Q bandpass
filter with around a 30dB/octave fall off will remove all the trash first.
You aren't even bothered about phase issues - just the fundamental
frequency. And in the limit you can use something like an FM detector if
you want.

There are a million ways to skin this cat, and none are hard.


Andy


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

On 02/05/13 10:02, Andy Champ wrote:
On 01/05/2013 14:54, wrote:
idf all 2KW+ kettles had a 1/2 power switch then my first try would
be to turn those kettles is 1/2 power them, I wouldn't turn off
motors or mmoving things such as food blenders.
I'd agree there. There are many things can be turned off or down if
its ever worth it. Today its mostly not though.


Not much point. The kettle will consume the same number of joules,
just spread over 10 minutes instead of 5. I suppose it might help the
ad break, but at the cost of making the viewer miss the beginning of
the next bit.

In fact it will probably consume very slightly _more_ owing to heat
loss through the casing.


yup. just like running backup hot standby for windmills does.

Its a bunch of ********, is smart gridding.

If you do Fourier anaylsis on wind power, it has a dominant period of
around 4 days. So anythuing thats going to make a difference must be
capable of being switched off for that length of time. well not much is.
Solar is better with the second most dominant period being one day. But
the MOST dominant period is ONE YEAR!! so with solar, you have to power
**** down for the whole winter.

This isn't a serious solution to a technical problem: Its smoke and
mirrors to pretend that there is a solution to renewable intermittency.
To keep the subsidies rolling in for a few more years.


Like a pan european grid of high capacity, or solar farms in Africa, or
whatever. Its all ********. Its just another EU road that goes nowhere
- money spent on something no one wants or needs, because the contractor
who built it was in with the Party. Or it was part of some drunken
vision someone had in a Brussels restaurant after too much Hermitage.

Like HS" 'We must have a pan Europe network of high speed trains: What
about Britain? Their existing lines are crap. So build a new one!"

How about "spend 1/3rd as much upgrading ALL the UKs lines instead? No,.
That wont do! WE must have Grand Projects to Show We Are Dong
Something." And spending 1/3rd as much is simply not what we do here.
Normally we spend three times as much, so everyone gets rich! And
achieve nothing of any value! That's the Party way sir! That's our core
priniciples of international socialism!.



Andy


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

On Wednesday, May 1, 2013 12:03:43 PM UTC+1, Man at B&Q wrote:
On 1 May, 11:11, whisky-dave wrote:

On Wednesday, May 1, 2013 12:33:51 AM UTC+1, wrote:

On Tuesday, April 30, 2013 11:35:49 PM UTC+1, The Other Mike wrote:



Equip the entire country of 24 million household with identical fridge freezers



and on average only 1/24 of them would be requiring power per one hour period.



They don't all turn on at precisely 17:32:06 and each present 4.8kW load to the



grid.



So for a typical A++ rated fridge freezer your entire demand control capability



for one hour is 600MW for an installed base of 24 million fridge freezers.



Install the same overall level of demand control for a few hundred commercial or



industrial consumers and the payback for the customer is much quicker, the costs



of implementing it are significantly lower for all parties, the customer sees



100% return on their invested capital in five years or so. The infrastructure to



support this demand control exists now and has done for a few decades. *Above



all it requires no investment from anyone but the customer.



All smart metering schemes will require wiring changes/appliance



changes/infrastructure changes. *The benefit to the domestic end user is near



zero. *The benefit to grid system operator and distribution network operator is



near zero. *The only ones that benefit are the parasites supplying and



installing the appliances / equipment.



If the government keep their stupid fingers out, it won't be long before appliances with this feature are available for an extra £5.



No you'll be entered into a free prize draw....



*An 8 bit cpu can respond to frequency,



Not that easily,



Rubbish.

meaningless.




and I doubt using that method would be very successful.

Far better to have teh aplience switched off on demand from the suplier than wait for the frequency to alter which would be difficult to measure cheaply.



Be silly to have to measure the frequency of every device.



Be even silier to have to have power line comms hardware and asociated

software stack running on every device.

You'd only need it on devices you wish to power down or otherwise alter their power consumption remotely. We actually run student projects on this type of thing. One studetn this year is doing "Home Automation example using Android application and Arduino board" turing off things remotely has been a goal for amn a year, we had a system back in teh 80s where you'd phone your landline where a hardware systems would contol lighting and heating. Thgis was workable but rather expensive on hardware, but it worked.

On May 2, 10:58*am, whisky-dave wrote:
On Wednesday, May 1, 2013 12:03:43 PM UTC+1, Man at B&Q wrote:
On 1 May, 11:11, whisky-dave wrote:

On Wednesday, May 1, 2013 12:33:51 AM UTC+1, wrote:

On Tuesday, April 30, 2013 11:35:49 PM UTC+1, The Other Mike wrote:

Equip the entire country of 24 million household with identical fridge freezers

and on average only 1/24 of them would be requiring power per one hour period.

They don't all turn on at precisely 17:32:06 and each present 4.8kW load to the

grid.

So for a typical A++ rated fridge freezer your entire demand control capability

for one hour is 600MW for an installed base of 24 million fridge freezers.

Install the same overall level of demand control for a few hundred commercial or

industrial consumers and the payback for the customer is much quicker, the costs

of implementing it are significantly lower for all parties, the customer sees

100% return on their invested capital in five years or so. The infrastructure to

support this demand control exists now and has done for a few decades. *Above

all it requires no investment from anyone but the customer.

All smart metering schemes will require wiring changes/appliance

changes/infrastructure changes. *The benefit to the domestic end user is near

zero. *The benefit to grid system operator and distribution network operator is

near zero. *The only ones that benefit are the parasites supplying and

installing the appliances / equipment.

If the government keep their stupid fingers out, it won't be long before appliances with this feature are available for an extra £5.

No you'll be entered into a free prize draw....

*An 8 bit cpu can respond to frequency,

Not that easily,

Rubbish.

meaningless.


That's a good summary of your input so far.

MBQ

On May 1, 1:54*pm, whisky-dave wrote:

Measuring low frequecies accuratly is more difficult than you think.

It's no more difficult than measuring any other frequency, just
depends how long you are prepared to wait.

What you have to do is count cycles in one second yuod get perhaps 47 or 53 so you need to average it out especailly in times of high or low demand.
So you need to sample it for at least 10 seconds to giove you 0.1 resoultion and in that time the situation can change.

You measure the period using the MPUs timer running at a much higher
rate. That gives you 50 readings poer second that can be averaged.

MBQ

On 02/05/13 10:17, Dave Liquorice wrote:
On Thu, 02 May 2013 09:40:07 +0100, The Natural Philosopher wrote:

Frequency is less important now than it was as there are fewer timing
devices rely on it.
Tell that to the German factories running synchronous motors that are
having f to intsall massive UPS/inverters because sudden fluctuations
in the mains frequency due to sun coming out/wind gust coming along are
destroying the machines the motors drive.
So 2 GW can drop off the euro frequency zone and produce a 0.05 Hz change
in the frequnecy but a few wind mills or photo voltaics can shove the
frequency out of spec?
do you know how MUCH solar energy is n germany. IIRC its about 30GW
capacity, and it goes on a sunny summers day from 30GW to the square
root of **** all when the sun sets.

http://en.wikipedia.org/wiki/Solar_power_in_Germany

Its not a few windmills or photovoltaics. Its MASSIVE. So MASSIVE they
ae having to buld 20 coal fired power stations to back it up, all of
whch will be powered up and running all day to cope with the MASSIVE
drop off at sunset.



If the factory motors or machinery can't handle within supply
specification frequency variations there is something wrong with them.

They can. But the German grid is incapable of keeping TO that
specification. They are talking of relaxing the specification. Worse, is
not the actual amount of variation, its the speed with which it happens.
the grid is upping and downing frequency and power wise over period in
the *seconds* range. Beyond the ability of even hydro to compensate for.

Ad the reason is not hard to see. In spinning turbines of large
dimensions in conventional power stations there is enough energy on the
inertia of the rotors to smooth out any massive sudden loads. And demand
fluctuates smoothly - yes you get the odd blip when everybody swtches on
a kettle after coronation street, But that only happens one a day and
all te pwoer here is from conventional power stations.

Inverters have no inertia. Solar panels and windmills fed through
inverters have zero storage. so the possibility of sudden and massive
swings in frequency is built right in.

fluctuating demand is a bad enough issue to cope with without compunding
the problem by adding very fast acting massive capacity of unpredictable
intermittency on to it.

Its so bad the Czechs have indicated that they may disconnect from the
German grid if it gets worse.

I am not making this up, its well documented.



Or are you saying, counter to what everyone says, the bit of the Euro
frequency zone in Germany can alter in frequency relative to the rest?



--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

On Thursday, May 2, 2013 11:22:08 AM UTC+1, Man at B&Q wrote:
On May 1, 1:54*pm, whisky-dave wrote:



Measuring low frequecies accuratly is more difficult than you think.



It's no more difficult than measuring any other frequency, just

depends how long you are prepared to wait.

That is the problem.

if you're in charge of the grid and you know that as soon as Eastenders is over 5 million people will turn on their kettles you have to act before that happens NOT 30 seconds after.



What you have to do is count cycles in one second yuod get perhaps 47 or 53 so you need to average it out especailly in times of high or low demand.

So you need to sample it for at least 10 seconds to giove you 0.1 resoultion and in that time the situation can change.



You measure the period using the MPUs timer running at a much higher

rate. That gives you 50 readings poer second that can be averaged.

to late, you need to act before your power station overloads not after it's happened that's the point, that's why they currently (pun intened), ramp up the avaialbe supply when they know aheavy demand is on the way.
I nearly had to do that here, phoning up teh local hospital and the local generaring board when we fired up our 6.6MV van-deer-graff gen.
Before the event not after or during !

On Thu, 02 May 2013 10:10:43 +0100, Andy Champ wrote:

On 01/05/2013 20:35, Ian Jackson wrote:
In message , Andy Champ
writes
On 30/04/2013 20:51, Ian Jackson wrote:
In message , Andy Champ
writes
Yes. And?

If you get an increased load, surely you can maintain speed by
reducing the excitation current - can't you?

This will result in a reduction of generator output voltage.

That's the idea. To reduce power consumption by reducing voltage, but
_without_ changing the frequency. Apparently the UK grid can't do it.

If you lower the voltage at the power station (instead of allowing the
frequency to drop), and somewhere down the line there are automatic
re-adjustments to try to maintain the correct voltage, more current will
be drawn from the power station. If the power station again reduces its
voltage, the same thing will happen again. Presumably it's all a careful
balancing act involving both voltage and frequency.

I think as the generator slows the voltage drops, and this results in a
slightly lower consumption (not if taps are changed, or for a SMPSU, but
for resistive loads and some simple devices) The frequency drop has
B**** all effect. But ICBW.

Andy

The voltage at the generator terminals is for all practical purposes (at least
in the context of this discussion) held at a constant level regardless of load,
as is everything across the super grid until the first transformer that has tap
changers.

Voltage to consumers can be reduced without the generators changing their own
terminal voltage. It happens many times a day as load changes (mainly industrial
load)

During the day a transformer may be on tap x of 20, at night on tap y.
During ALL this period the generator is at a constant voltage (around 15kV, the
400kV grid system is at 400kV, the 275kV grid system at 275kV and the 132kV grid
system at 132kV Below that distribution voltage level of 132kV the voltage on
all the lower voltage grids can vary and can be reduced in a number of stages to
lower demand whilst keeping voltage to the consumer within the statutory voltage
limits of 216V - 253V. This is an existing control regime that has existed for
half a century in the UK.

It doesn't matter if the load on the grid is 30GW 50GW or 60GW, wind turbines
are swinging output up and down like a whores drawers, the frequency is low or
high, the voltage at the generator terminals will *always* be controlled towards
a predefined setpoint defined by the manufacturer of the generator maybe 50
years ago.

http://books.google.co.uk/books?id=L7o4TitajRIC&pg=PA11&dq=automatic+voltage +regulator&hl=en&sa=X&ei=TjGCUZ_FDoXy7Abtp4DoDQ&ve d=0CEEQ6AEwAQ#v=onepage&q=automatic%20voltage%20re gulator&f=false


scroll to page 13

Frequency is determined by the speed of rotation. If speed of rotation starts
dropping more steam is admitted It's very similar in response to cruise control
on a relatively flat road.

If more steam is admitted then more fuel has to be burnt to maintain the steam
pressure and temperature.


--

On May 2, 11:50*am, whisky-dave wrote:
On Thursday, May 2, 2013 11:22:08 AM UTC+1, Man at B&Q wrote:
On May 1, 1:54*pm, whisky-dave wrote:

Measuring low frequecies accuratly is more difficult than you think.

It's no more difficult than measuring any other frequency, just

depends how long you are prepared to wait.

That is the problem.

if you're in charge of the grid and you know that as soon as Eastenders is over 5 million people will turn on their kettles you have to act before that happens NOT 30 seconds after.

Completely different situation. You know in advance that Eastenders is
on and have the spining reserve to cope. It happens all the time
already.

This thread is about micro-management of the grid by switching
individual appliances.

MBQ

On Thursday, May 2, 2013 10:12:21 AM UTC+1, Andy Champ wrote:
On 01/05/2013 16:04, whisky-dave wrote:

The average watch cyrstal is 32.768 KHz, which is how they divide down to 1Hz

2 ^22 .



2^22 ~= 4M. I think you mean 2^15.

oops yes I was getting confused with my stock of 4.194MHz crystals.
Someone asked me to get some 32.678MHz in stock too.





Andy

On Thursday, May 2, 2013 12:10:10 PM UTC+1, Man at B&Q wrote:
On May 2, 11:50*am, whisky-dave wrote:

On Thursday, May 2, 2013 11:22:08 AM UTC+1, Man at B&Q wrote:

On May 1, 1:54*pm, whisky-dave wrote:



Measuring low frequecies accuratly is more difficult than you think..



It's no more difficult than measuring any other frequency, just



depends how long you are prepared to wait.



That is the problem.



if you're in charge of the grid and you know that as soon as Eastenders is over 5 million people will turn on their kettles you have to act before that happens NOT 30 seconds after.



Completely different situation. You know in advance that Eastenders is

on and have the spining reserve to cope. It happens all the time

already.

We have enough capactity to cope now, the worry is that we won;t in the future so how will it be managed.


This thread is about micro-management of the grid by switching

individual appliances.

It's not about micro-management, check the title it was wheher or not smart meters could turn fridge/freezers off, now why would they want to turn them off if as you say above they already manage it.

On Wed, 1 May 2013 22:03:48 -0700 (PDT), harry
wrote:

Changing tappings on transformers does not help with any load changes.

Yes it does. It's the primary means of voltage control on the UK distribution
networks. It is one of the key parts of demand reduction to control stability on
the grid during an unexpected loss of generation.

BTW, I worked for years in an EB and never came a cross a local
transformer that changed tappings automatically. You'll have to
explain how that works.
None of the transformers round here do.

It happens at the bulk supply points. Usually at the first point on the network
where the voltage drops below 132kV.


--

On Wed, 1 May 2013 22:28:22 -0700 (PDT), harry
wrote:

All these PV panels/small wind turbines will need controlling at some
point in the future. As they become more numerous, they can't be left
running uncontrolled as at the moment.

They should have been strangled at birth

The control will come from the masses. not from smart meters. FIT parasites
fitted to ducking stools to entertain those with a more responsible attitude to
energy, mass destruction live on TV five nights a week of wind turbines 'Bang
Goes The Wind Turbine' Solar panels ripped off roofs and thrown in landfill by
angry mobs of Tunbridge Wells based housewives.

We ain't seen nothing yet.

No we haven't. The return to a CO2 producing economy to combat this extreme
global cooling is gaining momentum day by day.


--

On Thu, 02 May 2013 10:17:32 +0100 (BST), "Dave Liquorice"
wrote:

On Thu, 02 May 2013 09:40:07 +0100, The Natural Philosopher wrote:

Frequency is less important now than it was as there are fewer timing
devices rely on it.

Tell that to the German factories running synchronous motors that are
having f to intsall massive UPS/inverters because sudden fluctuations
in the mains frequency due to sun coming out/wind gust coming along are
destroying the machines the motors drive.

So 2 GW can drop off the euro frequency zone and produce a 0.05 Hz change
in the frequnecy

As I said in my previous posting. It was the comments of someone, can't recall
who. They provided no supporting evidence and I cannot find anything to back it
up (despite having access to some non public sources)


--

On May 2, 9:25*am, The Natural Philosopher
wrote:
On 02/05/13 06:10, harry wrote:







On May 1, 7:01 pm, Tim Streater wrote:
In article
,

* harry wrote:
On May 1, 9:52 am, Tim Streater wrote:
In article
,
* harry wrote:
If each appliance is fitted with a "smart device", then no changes are
needed to the home wiring.
I would have thought is better to have "essential" and
"non-essential" circuits in every house.
And you think the teenagers are going to remember which socket to plug
something in to? Or the average person, come to that.
You think anyone is going to convert their existing house to that - put
all your furniture in storage, move out, have all the walls bashed
around to have a second set of cabling installed, replaster, complete
redecoration, move back in.
Dream on.
You are a very ignorant person.
This has been done for years in hospitals because the emergency
generators are often not large enough to meet the full load.
Essential sockets are usually red.
In acute wards, there are no non-essential sockets.
Most essential equipment is permanently connected anyway.
I wasn't talking about commercial property, now was I? I was talking
about domestic.

We are talking about what might be done in the future.
Lots of these ideas being put about have been done for years in
commercial/industrial situations.

Eg, the thread on energy efficient pumps.
Which you average local plumber doesn't understand.

Condensing boilers were used commercially for years before they became
the domestic norm.

Heating system controls were used commercially long before domestic
use too.

All this stuff becomes viable domestically as the cost of fuel rises.

Lot of people round here need to get their heads out of their arses.
You actually need a zero energy house.

or alternatively build ****loads of nuclear power stations and make
energy cheap enough so we don't have to spend billions on finding ways
to not use it.



Nuclear is the most expensive option by far. And we haven't even fixed
the waste disposal problem from the past yet.

The taxpayer will be subsidising it in a big way. If it happens at
all.
All is coming out re the costs.

http://www.guardian.co.uk/environmen...-power-station

http://www.telegraph.co.uk/finance/n...ive-years.html

On May 2, 9:40*am, The Natural Philosopher
wrote:
On 02/05/13 06:32, harry wrote:







On May 1, 8:35 pm, Ian Jackson
wrote:
In message , Andy Champ
writesOn 30/04/2013 20:51, Ian Jackson wrote:
In message , Andy Champ
writes
Yes. And?
If you get an increased load, surely you can maintain speed by
reducing the excitation current - can't you?
This will result in a reduction of generator output voltage.
That's the idea. To reduce power consumption by reducing voltage, but
_without_ changing the frequency. Apparently the UK grid can't do it.
If you lower the voltage at the power station (instead of allowing the
frequency to drop), and somewhere down the line there are automatic
re-adjustments to try to maintain the correct voltage, more current will
be drawn from the power station. If the power station again reduces its
voltage, the same thing will happen again. Presumably it's all a careful
balancing act involving both voltage and frequency.
--
Ian
The object of the exercise is to maintain frequency and voltage at a
constant level. Ideally only current varies.

The problem is local voltage fluctuations.

Frequency is less important now than it was as there are fewer timing
devices rely on it.

Tell that to the German factories running synchronous motors that are
having f to intsall massive UPS/inverters because sudden fluctuations in
the mains frequency due to sun coming out/wind gust coming along are
destroying the machines the motors drive.

Some times I wonder if you actually believe all this ******** harry, or
whether its just you way of amusing yourself by pretending that you do,
or whether you actually are a SPIV and make a living out of selling
useless irrelevant technology to gullible people.

--
Ineptocracy

The reason the power from turbines is rectified then inverted via a
grid link inverter is so they avoid all the problems of
synchronisation.
In different wind speeds they need to run at different speeds to be
efficient.
http://www.newenco.co.uk/EEI-Wind-In...FS7KtAodKUUAqA

There are much bigger ones available too.

So you half wit, the wind turbines are not synchonised with the grid.

And PV panels generate DC so they are not synchronised either.

Which all goes to show how full of **** you are ranting on about
topics you have zero knowledge about.
As usual.

On May 2, 8:56*am, polygonum wrote:
On 02/05/2013 06:28, harry wrote:










The street is what you need to know about.
The frequency business is ********.

If the voltage falls locally future smart meters could "report back"
and turn a few local wind turbines/PV panels on. *;-)

Or maybe some of these as they become common.
http://www.ecpower.co.uk/english/
(Co-generation)

Or maybe stored power in electric vehicle batteries.

This is what Smart Grid technology is about.
All these PV panels/small wind turbines will need controlling at some
point in the future. As they become more numerous, they can't be left
running uncontrolled as at the moment.

And they will also cut off non essential thing if needed.

Anybody who co-operates with all this will be rewarded. (As with PV/
other renewable power at the moment)

The important bit will be to monitor all this an there will be
financial inducements for people to do this. ie different prices for
importing/exporting power at different times.

We ain't seen nothing yet.

Sounds wonderful - you have charged your electric vehicle using solar
panels, along comes a grid issue, so your vehicle battery is discharged
into the grid - along with any electricity your solar panels are producing.

End result, flat battery. And goodness knows what else unable to run due
to being cut off.

At least with a traditional power cut you don't lose that which you had.
At least with petrol they don't empty your tank during power cuts. Mind,
if they autostarted your little backup generator, and fed that
electricity into the grid as well, they could then empty your
generator's fuel tank quite nicely.

--
Rod

It's a serious idea that has been mooted for some time.
Lots of electric cars BTW, not just mine.

And re the generator, see my link. This is a co-generation device for
the home. Runs on gas BTW.

On May 2, 4:03*pm, harry wrote:


Frequency is less important now than it was as there are fewer timing
devices rely on it.

Tell that to the German factories running synchronous motors that are
having f to intsall massive UPS/inverters because sudden fluctuations in
the mains frequency due to sun coming out/wind gust coming along are
destroying the machines the motors drive.

Some times I wonder if you actually believe all this ******** harry, or
whether its just you way of amusing yourself by pretending that you do,
or whether you actually are a SPIV and make a living out of selling
useless irrelevant technology to gullible people.

--
Ineptocracy

The reason the power from turbines is rectified then inverted via a
grid link inverter is so they avoid all the problems of
synchronisation.
In different wind speeds they need to run at different speeds to be
efficient.

Gosh! You don't say!

There are much bigger ones available too.

Wow!

So you half wit, the wind turbines are not synchonised with the grid.

Er, where did he say they were?

And PV panels generate DC so they are not synchronised either.

Where did anyone claim otherwise?

Which all goes to show how full of **** you are ranting on about
topics you have zero knowledge about.

You have just demonstrated you know f**k all about what happens to the
grid due to fluctuations in renewable energy.

MBQ

On May 2, 4:10*pm, "Man at B&Q" wrote:
On May 2, 4:03*pm, harry wrote:











Frequency is less important now than it was as there are fewer timing
devices rely on it.

Tell that to the German factories running synchronous motors that are
having f to intsall massive UPS/inverters because sudden fluctuations in
the mains frequency due to sun coming out/wind gust coming along are
destroying the machines the motors drive.

Some times I wonder if you actually believe all this ******** harry, or
whether its just you way of amusing yourself by pretending that you do,
or whether you actually are a SPIV and make a living out of selling
useless irrelevant technology to gullible people.

--
Ineptocracy

The reason the power from turbines is rectified then inverted via a
grid link inverter is so they avoid all the problems of
synchronisation.
In different wind speeds they need to run at different speeds to be
efficient.

Gosh! You don't say!

There are much bigger ones available too.

Wow!

So you half wit, the wind turbines are not synchonised with the grid.

Er, where did he say they were?

And PV panels generate DC so they are not synchronised either.

Where did anyone claim otherwise?

Which all goes to show how full of **** you are ranting on about
topics you have zero knowledge about.

You have just demonstrated you know f**k all about what happens to the
grid due to fluctuations in renewable energy.

MBQ

Grid tie inverters generate whatever frequency they "see" on the gird
connection. So their operation has no effect of the grid frequency.

However the local voltage changes.
My PV panel increases local voltage (in my house) by around 2 volts
when running flat out.
My 16Kw shower drops the local voltage by seven volts when in use.

If I lived in town, it would be less than that. There would be larger
cables and transformers.

In message ,
whisky-dave writes
On Thursday, May 2, 2013 3:51:25 PM UTC+1, harry wrote:






It's ******** because as the frequency is the same everywhere in the

UK, what's the point of measuring it?

The ******** is on here too about how to measure it.

My grid link PV inverter measures the frequency, so any time you want

to know I can tell you.

It's usually less than 50Hz BTW.

http://www.gridwatch.templar.co.uk/

15:55 50.056Hz so what is it at your end.

checking my office with a maplin plugin thingy (probabley not that
acurate but :-
212V 51Hz, with the occasional 211V and 51Hz

Is it still not true that synchronous clocks are kept accurate by
ensuring that the correct number of cycles* (in the preceding 24 hours)
have been delivered by 8am every morning?
*My calculator tells me that the mains frequency should be 4,320,000
cycles per day.
--
Ian

harry wrote:

Grid tie inverters generate whatever frequency they "see" on the gird
connection. So their operation has no effect of the grid frequency.

Not when they're only generating a tiny percentage of demand, no. If
they were in the same proportion as the German installations, then they
would, as the grid frequency would vary with the load on the thermal,
non-renewable, generators.

However the local voltage changes.
My PV panel increases local voltage (in my house) by around 2 volts
when running flat out.
My 16Kw shower drops the local voltage by seven volts when in use.

If I lived in town, it would be less than that. There would be larger
cables and transformers.

With a correspondingly higher user density, and while *your* shower
might not drop the voltage by 7 volts, when everyone on your street
takes a shower or puts the kettle on, the drop is likely to be about the
same. In the same way, if everybody had PV panels, the local voltage in
the street would rise by a couple of volts in sunny weather.

The grid has been built as cheaply as possible to give the required
performance. Voltage variations through the day are roughly the same no
matter where you are, unless you are next to a substation.

--
Tciao for Now!

John.

harry wrote:
On May 2, 4:00 pm, whisky-dave wrote:
On Thursday, May 2, 2013 3:51:25 PM UTC+1, harry wrote:

It's ******** because as the frequency is the same everywhere in the
UK, what's the point of measuring it?
The ******** is on here too about how to measure it.
My grid link PV inverter measures the frequency, so any time you want
to know I can tell you.
It's usually less than 50Hz BTW.
http://www.gridwatch.templar.co.uk/

15:55 50.056Hz so what is it at your end.

checking my office with a maplin plugin thingy (probabley not that acurate but :-
212V 51Hz, with the occasional 211V and 51Hz

49.96 my inverter is showing @1616h.

And how accurately is the frequency counter on your inverter calibrated?
When was the last time it was checked against an accurate external
reference?

I would expect the ones used to monitor the grid are accurate to within
parts per million and are checked reguarly against at least a secondary
standard.

--
Tciao for Now!

John.

On Thursday, May 2, 2013 4:36:41 PM UTC+1, Ian Jackson wrote:
In message ,

whisky-dave writes

On Thursday, May 2, 2013 3:51:25 PM UTC+1, harry wrote:













It's ******** because as the frequency is the same everywhere in the



UK, what's the point of measuring it?



The ******** is on here too about how to measure it.



My grid link PV inverter measures the frequency, so any time you want



to know I can tell you.



It's usually less than 50Hz BTW.



http://www.gridwatch.templar.co.uk/



15:55 50.056Hz so what is it at your end.



checking my office with a maplin plugin thingy (probabley not that

acurate but :-

212V 51Hz, with the occasional 211V and 51Hz



Is it still not true that synchronous clocks are kept accurate by

ensuring that the correct number of cycles* (in the preceding 24 hours)

have been delivered by 8am every morning?

*My calculator tells me that the mains frequency should be 4,320,000

cycles per day.

Only if your day is 24 hours, when it's actually 23 hours, 56 minutes and 4.090 seconds so about 4,308,453.5 cycles.





--

Ian

On 02/05/13 15:47, harry lied again:
Nuclear is the most expensive option by far. And we haven't even fixed
the waste disposal problem from the past yet. The taxpayer will be
subsidising it in a big way. If it happens at all. All is coming out
re the costs.
http://www.guardian.co.uk/environmen...-power-station
http://www.telegraph.co.uk/finance/n...ive-years.html


More unsupported drivel.

nuclear is way more competitive than any renewable bar wast burning and
hydro.

The argument with EDF is on account of them wanting 10p a unit
guaranteed,. renewable onshore is guranteed at 15p.

It costs more to build an offshore wind farm than a nuke of simar
capacity which will produce 12 times work electricity over its service life.

There is no problem with waste disposal.


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

On 02/05/13 16:03, harry wrote:
On May 2, 9:40 am, The Natural Philosopher

Tell that to the German factories running synchronous motors that are
having f to intsall massive UPS/inverters because sudden fluctuations in
the mains frequency due to sun coming out/wind gust coming along are
destroying the machines the motors drive.

Some times I wonder if you actually believe all this ******** harry, or
whether its just you way of amusing yourself by pretending that you do,
or whether you actually are a SPIV and make a living out of selling
useless irrelevant technology to gullible people.

--
Ineptocracy
The reason the power from turbines is rectified then inverted via a
grid link inverter is so they avoid all the problems of
synchronisation.
In different wind speeds they need to run at different speeds to be
efficient.
http://www.newenco.co.uk/EEI-Wind-In...FS7KtAodKUUAqA

There are much bigger ones available too.

So you half wit, the wind turbines are not synchonised with the grid.

the output from their inverters is.

And PV panels generate DC so they are not synchronised either.

Which all goes to show how full of **** you are ranting on about
topics you have zero knowledge about.
As usual.


However none of what you say has any relevance to what I was talking
about anyway. Its another weak attempt at a pathetic straw man.

**** off harry.

Wossa matter? cant sell any solar panels anymore?



--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

On 02/05/2013 16:04, harry wrote:
On May 2, 8:56 am, polygonum wrote:
On 02/05/2013 06:28, harry wrote:










The street is what you need to know about.
The frequency business is ********.

If the voltage falls locally future smart meters could "report back"
and turn a few local wind turbines/PV panels on. ;-)

Or maybe some of these as they become common.
http://www.ecpower.co.uk/english/
(Co-generation)

Or maybe stored power in electric vehicle batteries.

This is what Smart Grid technology is about.
All these PV panels/small wind turbines will need controlling at some
point in the future. As they become more numerous, they can't be left
running uncontrolled as at the moment.

And they will also cut off non essential thing if needed.

Anybody who co-operates with all this will be rewarded. (As with PV/
other renewable power at the moment)

The important bit will be to monitor all this an there will be
financial inducements for people to do this. ie different prices for
importing/exporting power at different times.

We ain't seen nothing yet.

Sounds wonderful - you have charged your electric vehicle using solar
panels, along comes a grid issue, so your vehicle battery is discharged
into the grid - along with any electricity your solar panels are producing.

End result, flat battery. And goodness knows what else unable to run due
to being cut off.

At least with a traditional power cut you don't lose that which you had.
At least with petrol they don't empty your tank during power cuts. Mind,
if they autostarted your little backup generator, and fed that
electricity into the grid as well, they could then empty your
generator's fuel tank quite nicely.

--
Rod

It's a serious idea that has been mooted for some time.
Lots of electric cars BTW, not just mine.

And re the generator, see my link. This is a co-generation device for
the home. Runs on gas BTW.


So you would be happy to donate (or loan) the charge from your vehicle?
Without a crystal ball to know when you will be able to re-charge it?

--
Rod

On 02/05/13 16:04, harry wrote:
On May 2, 8:56 am, polygonum wrote:
On 02/05/2013 06:28, harry wrote:










The street is what you need to know about.
The frequency business is ********.
If the voltage falls locally future smart meters could "report back"
and turn a few local wind turbines/PV panels on. ;-)
Or maybe some of these as they become common.
http://www.ecpower.co.uk/english/
(Co-generation)
Or maybe stored power in electric vehicle batteries.
This is what Smart Grid technology is about.
All these PV panels/small wind turbines will need controlling at some
point in the future. As they become more numerous, they can't be left
running uncontrolled as at the moment.
And they will also cut off non essential thing if needed.
Anybody who co-operates with all this will be rewarded. (As with PV/
other renewable power at the moment)
The important bit will be to monitor all this an there will be
financial inducements for people to do this. ie different prices for
importing/exporting power at different times.
We ain't seen nothing yet.
Sounds wonderful - you have charged your electric vehicle using solar
panels, along comes a grid issue, so your vehicle battery is discharged
into the grid - along with any electricity your solar panels are producing.

End result, flat battery. And goodness knows what else unable to run due
to being cut off.

At least with a traditional power cut you don't lose that which you had.
At least with petrol they don't empty your tank during power cuts. Mind,
if they autostarted your little backup generator, and fed that
electricity into the grid as well, they could then empty your
generator's fuel tank quite nicely.

--
Rod
It's a serious idea that has been mooted for some time.

Its certainly been mooted for sometime but its not serious harry. You
only need to do the sums to see it is utter nonsense.

But it fooled you , which was the purpose of it.

Lots of electric cars BTW, not just mine.

If every household in the country had a 22Kwh car fully charged, it
would run the grid for 10 hours in winter before the entire country
blacked out.

So if all we had was solar and wind, that's exactly what would happen in
a dark windless 14 hour night.

No more need be said. Its ********.



And re the generator, see my link. This is a co-generation device for
the home. Runs on gas BTW.

oh great. instead of 60% efficient central generation we have poxy
little domestic gas boilers doing 30% efficient generation..

sheesh harry, you are a dumb **** if you think that one will fly.

--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

On 02/05/13 16:36, Ian Jackson wrote:

Is it still not true that synchronous clocks are kept accurate by
ensuring that the correct number of cycles* (in the preceding 24
hours) have been delivered by 8am every morning?
*My calculator tells me that the mains frequency should be 4,320,000
cycles per day.
AFAIK the daily average is always exactly 50hz.

HOWEVER a friend of mine on encountering the gridwatch site said 'you
don't happen to have a record of frequency over the last two years do
you' I said 'yes I do' 'what is the max and min and average deviation
frequencies you have seen' I told him.

"**** now I know why that instrrument that used mains frequency to do
timing was always drifting about..I TOLD them it need a crystal clock
added to it, but I couldn't PROVE it..."



--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

On Thu, 2 May 2013 07:51:25 -0700 (PDT), harry
wrote:

My grid link PV inverter measures the frequency, so any time you want
to know I can tell you.
It's usually less than 50Hz BTW.

Last couple of minutes

49.99 min

50.04 max

Measured with a Fluke 87 V in calibration

--

On 02/05/2013 16:26, harry wrote:
Grid tie inverters generate whatever frequency they "see" on the gird
connection. So their operation has no effect of the grid frequency.

However the local voltage changes.
My PV panel increases local voltage (in my house) by around 2 volts
when running flat out.
My 16Kw shower drops the local voltage by seven volts when in use.

If I lived in town, it would be less than that. There would be larger
cables and transformers.

Yeah but we had that discussion. Voltage swings cause frequency changes,
unless you take steps to compensate for them - more coal in the boiler,
or fiddle with the exciter current.

So even though your devices are not in themselves causing a frequency
swing, they are causing a voltage swing, and that causes spin speed
instability in synchronous rotating generators.

Andy

On 02/05/2013 11:54, The Other Mike wrote:
The voltage at the generator terminals is for all practical purposes (at least
in the context of this discussion) held at a constant level regardless of load,
as is everything across the super grid until the first transformer that has tap
changers.

Voltage to consumers can be reduced without the generators changing their own
terminal voltage. It happens many times a day as load changes (mainly industrial
load)

During the day a transformer may be on tap x of 20, at night on tap y.
During ALL this period the generator is at a constant voltage (around 15kV, the
400kV grid system is at 400kV, the 275kV grid system at 275kV and the 132kV grid
system at 132kV Below that distribution voltage level of 132kV the voltage on
all the lower voltage grids can vary and can be reduced in a number of stages to
lower demand whilst keeping voltage to the consumer within the statutory voltage
limits of 216V - 253V. This is an existing control regime that has existed for
half a century in the UK.

It doesn't matter if the load on the grid is 30GW 50GW or 60GW, wind turbines
are swinging output up and down like a whores drawers, the frequency is low or
high, the voltage at the generator terminals will*always* be controlled towards
a predefined setpoint defined by the manufacturer of the generator maybe 50
years ago.

http://books.google.co.uk/books?id=L7o4TitajRIC&pg=PA11&dq=automatic+voltage +regulator&hl=en&sa=X&ei=TjGCUZ_FDoXy7Abtp4DoDQ&ve d=0CEEQ6AEwAQ#v=onepage&q=automatic%20voltage%20re gulator&f=false


scroll to page 13

Frequency is determined by the speed of rotation. If speed of rotation starts
dropping more steam is admitted It's very similar in response to cruise control
on a relatively flat road.

If more steam is admitted then more fuel has to be burnt to maintain the steam
pressure and temperature.

I have no trouble understanding how intermittency will cause stability
problems. However...

Google won't let me read enough of that book

So the fiddle with the exciter current to maintain a fixed output
voltage, regardless of load? Surely at some point they must run out of
steam...

What actually controls the grid frequency? Is it the tap changing at the
132kV step down?

Andy

On Thursday, May 2, 2013 10:23:58 AM UTC+1, The Natural Philosopher wrote:
On 02/05/13 09:59, Andy Champ wrote:
On 01/05/2013 13:54, whisky-dave wrote:

You ought to measure the time for 50 (or something) cycles instead. If
you time it at the zero crossing that doesn't move about much.

Even so - yes, it's hard, especially with a noisy waveform.

don't be silly. an active low pass filter or even a 50hz high Q bandpass
filter with around a 30dB/octave fall off will remove all the trash first.

Yup. A capacitor, repeated counts and a few mistimes are cheaper.

You aren't even bothered about phase issues - just the fundamental
frequency. And in the limit you can use something like an FM detector if
you want.

countings cheaper

There are a million ways to skin this cat, and none are hard.

quite


NT

On 02/05/13 23:14, Andy Champ wrote:
On 02/05/2013 11:54, The Other Mike wrote:
The voltage at the generator terminals is for all practical purposes
(at least
in the context of this discussion) held at a constant level
regardless of load,
as is everything across the super grid until the first transformer
that has tap
changers.

Voltage to consumers can be reduced without the generators changing
their own
terminal voltage. It happens many times a day as load changes (mainly
industrial
load)

During the day a transformer may be on tap x of 20, at night on tap y.
During ALL this period the generator is at a constant voltage (around
15kV, the
400kV grid system is at 400kV, the 275kV grid system at 275kV and the
132kV grid
system at 132kV Below that distribution voltage level of 132kV the
voltage on
all the lower voltage grids can vary and can be reduced in a number
of stages to
lower demand whilst keeping voltage to the consumer within the
statutory voltage
limits of 216V - 253V. This is an existing control regime that has
existed for
half a century in the UK.

It doesn't matter if the load on the grid is 30GW 50GW or 60GW, wind
turbines
are swinging output up and down like a whores drawers, the frequency
is low or
high, the voltage at the generator terminals will*always* be
controlled towards
a predefined setpoint defined by the manufacturer of the generator
maybe 50
years ago.

http://books.google.co.uk/books?id=L7o4TitajRIC&pg=PA11&dq=automatic+voltage +regulator&hl=en&sa=X&ei=TjGCUZ_FDoXy7Abtp4DoDQ&ve d=0CEEQ6AEwAQ#v=onepage&q=automatic%20voltage%20re gulator&f=false



scroll to page 13

Frequency is determined by the speed of rotation. If speed of
rotation starts
dropping more steam is admitted It's very similar in response to
cruise control
on a relatively flat road.

If more steam is admitted then more fuel has to be burnt to maintain
the steam
pressure and temperature.

I have no trouble understanding how intermittency will cause stability
problems. However...

Google won't let me read enough of that book

So the fiddle with the exciter current to maintain a fixed output
voltage, regardless of load? Surely at some point they must run out
of steam...

What actually controls the grid frequency? Is it the tap changing at
the 132kV step down?

noo.


The way it goes is this. You start your powerstation and then when its
in phase with the grid, you connect it. At this point if you pull torque
off it. it will be a motor driven BY the grid, and as you increase
torque on it, it will start to phase lead the grid slightly and push
power onto it. You can control the voltage using the exciters - you
match that to the grid voltage.

If you open up the steam and push too much power all the grid speeds
up. Since voltage is both exciter current AND RPM, the voltage also
rises. so under normal loadings the load will affect voltage and
frequency together. The job of the grid controllers is to keep that
within limits. By (I think: this is where it gets hazy) running a real
time auction on prices. If the load goes up. the prices rises and
generators who want to deliver at that price open the throttles and do
so, Except intermittent renewables of course. they are outside any
market, getting more or less their FITS and ROCS and so its always
profitable for them irrespective of market price. Making life harder for
everyone else.

I am not sure what would happen if you changed excitation current on a
running jenny drastically. My gut feeling is that it would be a Very Bad
Thing, but I cant work out what would happen. It feels like the jenny
would go badly out of phase and start pushing massive currents through
itself without generating power and would go up in smoke. But I cant
quite remember the sums or pictire it.

the balancing system is interesting.

Nuclear generators have almost no incremental fuel costs at all. They
may not be profitable running at low electricity process at night, but
they dont save anything by switching off. That's more than anything is
why they run the baseload. Every other power station at some point will
say 'its cheaper NOT to burn the fuel and throttle back' that never
happens with nuclear. They can and are throttled a bit, but too much
throttling mucks up the reaction and leads to poisoning IIRC. However
one muke is cvurently on reduced power to save fuel till its next
reload, so they can do that.

At the other end of he spectrum intermittent renewables are
'irresponsible' with 'private incomes' of FITS and ROCS. SDo they will
be and are profitable irespective of market price of electricity and
they cant be turned down anyway. Just turned off altogether. So they are
always generating whatever the source will alllow as well.

Hydro is interesting. Most sites are more limited by water, than by
capacity. So they run a crafty game selling their precious water power
at the peak of demand. Day mainly. If te das however are full to
bursting, they might as well get what they can, so you see more hydro
after periods of heavy rain in offpeak times.

Coal seems to run as hard as it can, most of the time because coal is
cheaper than gas. Gas is the first to be taken off the grid when the
wind is blowing for example. One reason why renewable UK's predictions
about wind displacing coal and gas in the ratio they are on the grid,
one for one are ********. Also its a lot longer to get a coal plant up
than gas so they are generally not shut down but throttled back at night
when all the gas - or most of it - has been shut down. It looks like
some are closed over weekends though.


Gas is used sparingly because gas is expensive and gas sets are fast to
start, so in general they are off at night with just a few ticking over.
by day they are used to cover peaks because they can be ramped up and
down fast. In general wind and gas are playing in complementary fashion
in the UK, leaving coal and nuclear to cover the baseload. ..by and
large wind and solar do nothing for coal consumption but a lot for gas
usage. However its arguable as to whether this actually saves any gas
overall - the extra ramping involved in the gas probably negates any
actual reduction in the amount of electricity they generate.

returning to topic, the fact is that whereas voltage is locally
interesting and reflects the local power being drawn, and the local
impedance of the source, it doesn't really reflect overall national
demand. Frequency does. If you want a smart meter that doesn't have to
be taught anything about local conditions to modulate overall grid
demand, then you will use frequency.

But the real issue is how much load you could take off the grid anyway.
And as you will;l realise its at best 10% if that, and then only for a
few hours max.

To generate 30% of put electricity from renewables (and save about 5% of
fuel if that) we would need some way of handling a random 0-40GW
negative load on the grid. with our 8GW of nuclear, that would mean on
windy summer nights we would be throwing away up to 15GW of wind because
it cant be stored and we wouldn't need it. But on cold winter days with
no wind we might be short by 50GW and no amount of smart grid is going
to suddenly reduce demand from 55GW to 8GW or anything like it. That's
not even enough to run the trains.

SO it is easy to see that smart grids do feck all to actually cope with
renewable intermittentcy, in exactly the same way that renewable energy
does feck all to reduce carbon emissions.

They both represent solutions to the problem of appearing to Do
Something About Climate change whilst making a ****ing big profit and
not actually doing anything at all. All they have to do is convince an
unsophisticated electorate with no real idea about how anything works,
with a plausible narrative that conforms to their belief systems A
country full of harrys, in fact.

Its pure political fraud. But then, what isn't?

Of course in the end you have to keep the lights on, which is why twenty
dirty coal plants are being rush built in germany to paper over the
cracks in renewable energy.

So they can say 'we are generating 80% of our electricity with
renewables' and fail to mention that they haven't actually reduced
carbon emissions one iota. In fact, they have increased them.

But Greens are that ****ing stupid they will believe that they have,
which is all that matters.



Andy


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

On May 2, 11:14*pm, Andy Champ wrote:
On 02/05/2013 11:54, The Other Mike wrote:









The voltage at the generator terminals is for all practical purposes (at least
in the context of this discussion) held at a constant level regardless of load,
as is everything across the super grid until the first transformer that has tap
changers.

Voltage to consumers can be reduced without the generators changing their own
terminal voltage. It happens many times a day as load changes (mainly industrial
load)

During the day a transformer may be on tap x of 20, at night on tap y.
During ALL this period the generator is at a constant voltage (around 15kV, the
400kV grid system is at 400kV, the 275kV grid system at 275kV and the 132kV grid
system at 132kV *Below that distribution voltage level of 132kV the voltage on
all the lower voltage grids can vary and can be reduced in a number of stages to
lower demand whilst keeping voltage to the consumer within the statutory voltage
limits of 216V - 253V. *This is an existing control regime that has existed for
half a century in the UK.

It doesn't matter if the load on the grid is 30GW 50GW or 60GW, wind turbines
are swinging output up and down like a whores drawers, the frequency is low or
high, the voltage at the generator terminals will*always* *be controlled towards
a predefined setpoint defined by the manufacturer of the generator maybe 50
years ago.

http://books.google.co.uk/books?id=L7o4TitajRIC&pg=PA11&dq=automatic+...

scroll to page 13

Frequency is determined by the speed of rotation. *If speed of rotation starts
dropping more steam is admitted *It's very similar in response to cruise control
on a relatively flat road.

If more steam is admitted then more fuel has to be burnt to maintain the steam
pressure and temperature.

I have no trouble understanding how intermittency will cause stability
problems. However...

Google won't let me read enough of that book

So the fiddle with the exciter current to maintain a fixed output
voltage, regardless of load? *Surely at some point they must run out of
steam...

What actually controls the grid frequency? Is it the tap changing at the
132kV step down?

Andy

The grid frequency is controlled by the speedof the generators. The
only way to change that is change their speed. They are all linked
together no single generator can run faster than the others.
They are locked together as surely as they were all on the same shaft
by the alternating current they generate.

Before an alternator can be put on line, it has to be synchronised
with the grid, not only the speed but the angle of the shaft so that
the wave generated peaks at the same moment as all the rest.

This is a big problem for renewable technologies so they are linked to
the grid by a grid tie inverter which turns the DC from the (eg PV
panel) to the frequency it "sees" on the grid.

So the frequency is exactly the same everywhere on the grid.
If the grid is overloaded (which can happen nationally or locally) the
voltage will fall.
Sometimes the frequency will fall, but the two are only indirectly
linked. They can be independently controlled except when generators
are at their extreme upper load limit.

Even small changes in the load effect voltage. When you turn on an
electric kettle, there will be a measureable voltage drop at your
consumer unit.

In message , The Natural Philosopher
writes





I am not sure what would happen if you changed excitation current on a
running jenny drastically. My gut feeling is that it would be a Very
Bad Thing, but I cant work out what would happen. It feels like the
jenny would go badly out of phase and start pushing massive currents
through itself without generating power and would go up in smoke. But I
cant quite remember the sums or pictire it.

If you drastically changed the excitation current (either way), the
generator speed will unlock from the mains, and massive currents will
start pulsating in or out at the difference frequency. Presumably, they
have devices which detect such a condition, and these rapidly disconnect
the generator from the system, and also remove the power from the drive
shaft.









--
Ian

On 03/05/2013 00:17, The Natural Philosopher wrote:
On 02/05/13 23:14, Andy Champ wrote:
On 02/05/2013 11:54, The Other Mike wrote:
The voltage at the generator terminals is for all practical purposes
(at least
in the context of this discussion) held at a constant level
regardless of load,
as is everything across the super grid until the first transformer
that has tap
changers.

Voltage to consumers can be reduced without the generators changing
their own
terminal voltage. It happens many times a day as load changes (mainly
industrial
load)

During the day a transformer may be on tap x of 20, at night on tap y.
During ALL this period the generator is at a constant voltage (around
15kV, the
400kV grid system is at 400kV, the 275kV grid system at 275kV and the
132kV grid
system at 132kV Below that distribution voltage level of 132kV the
voltage on
all the lower voltage grids can vary and can be reduced in a number
of stages to
lower demand whilst keeping voltage to the consumer within the
statutory voltage
limits of 216V - 253V. This is an existing control regime that has
existed for
half a century in the UK.

It doesn't matter if the load on the grid is 30GW 50GW or 60GW, wind
turbines
are swinging output up and down like a whores drawers, the frequency
is low or
high, the voltage at the generator terminals will*always* be
controlled towards
a predefined setpoint defined by the manufacturer of the generator
maybe 50
years ago.

http://books.google.co.uk/books?id=L7o4TitajRIC&pg=PA11&dq=automatic+voltage +regulator&hl=en&sa=X&ei=TjGCUZ_FDoXy7Abtp4DoDQ&ve d=0CEEQ6AEwAQ#v=onepage&q=automatic%20voltage%20re gulator&f=false



scroll to page 13

Frequency is determined by the speed of rotation. If speed of
rotation starts
dropping more steam is admitted It's very similar in response to
cruise control
on a relatively flat road.

If more steam is admitted then more fuel has to be burnt to maintain
the steam
pressure and temperature.

I have no trouble understanding how intermittency will cause stability
problems. However...

Google won't let me read enough of that book

So the fiddle with the exciter current to maintain a fixed output
voltage, regardless of load? Surely at some point they must run out
of steam...

What actually controls the grid frequency? Is it the tap changing at
the 132kV step down?

noo.


The way it goes is this. You start your powerstation and then when its
in phase with the grid, you connect it. At this point if you pull torque
off it. it will be a motor driven BY the grid, and as you increase
torque on it, it will start to phase lead the grid slightly and push
power onto it. You can control the voltage using the exciters - you
match that to the grid voltage.

If you open up the steam and push too much power all the grid speeds
up. Since voltage is both exciter current AND RPM, the voltage also
rises. so under normal loadings the load will affect voltage and
frequency together. The job of the grid controllers is to keep that
within limits. By (I think: this is where it gets hazy) running a real
time auction on prices. If the load goes up. the prices rises and
generators who want to deliver at that price open the throttles and do
so, Except intermittent renewables of course. they are outside any
market, getting more or less their FITS and ROCS and so its always
profitable for them irrespective of market price. Making life harder for
everyone else.

I am not sure what would happen if you changed excitation current on a
running jenny drastically. My gut feeling is that it would be a Very Bad
Thing, but I cant work out what would happen. It feels like the jenny
would go badly out of phase and start pushing massive currents through
itself without generating power and would go up in smoke. But I cant
quite remember the sums or pictire it.

the balancing system is interesting.

Nuclear generators have almost no incremental fuel costs at all. They
may not be profitable running at low electricity process at night, but
they dont save anything by switching off. That's more than anything is
why they run the baseload. Every other power station at some point will
say 'its cheaper NOT to burn the fuel and throttle back' that never
happens with nuclear. They can and are throttled a bit, but too much
throttling mucks up the reaction and leads to poisoning IIRC. However
one muke is cvurently on reduced power to save fuel till its next
reload, so they can do that.

At the other end of he spectrum intermittent renewables are
'irresponsible' with 'private incomes' of FITS and ROCS. SDo they will
be and are profitable irespective of market price of electricity and
they cant be turned down anyway. Just turned off altogether. So they are
always generating whatever the source will alllow as well.

Hydro is interesting. Most sites are more limited by water, than by
capacity. So they run a crafty game selling their precious water power
at the peak of demand. Day mainly. If te das however are full to
bursting, they might as well get what they can, so you see more hydro
after periods of heavy rain in offpeak times.

Coal seems to run as hard as it can, most of the time because coal is
cheaper than gas. Gas is the first to be taken off the grid when the
wind is blowing for example. One reason why renewable UK's predictions
about wind displacing coal and gas in the ratio they are on the grid,
one for one are ********. Also its a lot longer to get a coal plant up
than gas so they are generally not shut down but throttled back at night
when all the gas - or most of it - has been shut down. It looks like
some are closed over weekends though.


Gas is used sparingly because gas is expensive and gas sets are fast to
start, so in general they are off at night with just a few ticking over.
by day they are used to cover peaks because they can be ramped up and
down fast. In general wind and gas are playing in complementary fashion
in the UK, leaving coal and nuclear to cover the baseload. ..by and
large wind and solar do nothing for coal consumption but a lot for gas
usage. However its arguable as to whether this actually saves any gas
overall - the extra ramping involved in the gas probably negates any
actual reduction in the amount of electricity they generate.

returning to topic, the fact is that whereas voltage is locally
interesting and reflects the local power being drawn, and the local
impedance of the source, it doesn't really reflect overall national
demand. Frequency does. If you want a smart meter that doesn't have to
be taught anything about local conditions to modulate overall grid
demand, then you will use frequency.

But the real issue is how much load you could take off the grid anyway.
And as you will;l realise its at best 10% if that, and then only for a
few hours max.

To generate 30% of put electricity from renewables (and save about 5% of
fuel if that) we would need some way of handling a random 0-40GW
negative load on the grid. with our 8GW of nuclear, that would mean on
windy summer nights we would be throwing away up to 15GW of wind because
it cant be stored and we wouldn't need it. But on cold winter days with
no wind we might be short by 50GW and no amount of smart grid is going
to suddenly reduce demand from 55GW to 8GW or anything like it. That's
not even enough to run the trains.

SO it is easy to see that smart grids do feck all to actually cope with
renewable intermittentcy, in exactly the same way that renewable energy
does feck all to reduce carbon emissions.

They both represent solutions to the problem of appearing to Do
Something About Climate change whilst making a ****ing big profit and
not actually doing anything at all. All they have to do is convince an
unsophisticated electorate with no real idea about how anything works,
with a plausible narrative that conforms to their belief systems A
country full of harrys, in fact.

Its pure political fraud. But then, what isn't?

Of course in the end you have to keep the lights on, which is why twenty
dirty coal plants are being rush built in germany to paper over the
cracks in renewable energy.

So they can say 'we are generating 80% of our electricity with
renewables' and fail to mention that they haven't actually reduced
carbon emissions one iota. In fact, they have increased them.

But Greens are that ****ing stupid they will believe that they have,
which is all that matters.

It might surprise you to know that I agree with pretty much everything
you say here. In addition Japan abandonning nuclear so suddenly will
also drive oil and coal prices much higher in the short to medium term.
They have no indigenous fossil fuels being a largely volcanic island.
Gas may be held low by the US fracking craze until that goes haywire.

ISTR that if a generator goes badly out of sync there are circuit
breakers that drop it offline before the grid can do any damage to it.

Some ICI works had their own power stations way back when and they were
grid connected most of the time but could isolate themselves and run the
plant even during the 3 day week. The works carparks were all quietly
covered in coal about a foot deep prior to the big strikes.

They did survive OK when the grid around them collapsed unexpectedly.
Obviously this was because many chemical processes do not take at all
kindly to the agitator or cooling water circulation stopping suddenly.

--
Regards,
Martin Brown

On Thu, 02 May 2013 21:55:51 +0100, Andy Champ wrote:

So even though your devices are not in themselves causing a frequency
swing, they are causing a voltage swing, and that causes spin speed
instability in synchronous rotating generators.

His generation is on the distribution network. If the volts rise the taps
change at the bulk supply point although 2v at 230v is SFA in the grand scheme
of things as its buried in the noise of everything else.

Germany might be different because of the scale of deployment and location of
the generation but in the UK embedded solar generation is viewed simply as
reduced demand (an an irritation) As much as it pains me to say, a few
thousand roofs adorned with solar panels make bugger all difference to the
operation of the UK Grid, the only damage is the pocket of consumers who are
being forced to subsidise FIT parasites.

--

On Thu, 02 May 2013 23:14:28 +0100, Andy Champ wrote:

On 02/05/2013 11:54, The Other Mike wrote:
The voltage at the generator terminals is for all practical purposes (at least
in the context of this discussion) held at a constant level regardless of load,
as is everything across the super grid until the first transformer that has tap
changers.

Voltage to consumers can be reduced without the generators changing their own
terminal voltage. It happens many times a day as load changes (mainly industrial
load)

During the day a transformer may be on tap x of 20, at night on tap y.
During ALL this period the generator is at a constant voltage (around 15kV, the
400kV grid system is at 400kV, the 275kV grid system at 275kV and the 132kV grid
system at 132kV Below that distribution voltage level of 132kV the voltage on
all the lower voltage grids can vary and can be reduced in a number of stages to
lower demand whilst keeping voltage to the consumer within the statutory voltage
limits of 216V - 253V. This is an existing control regime that has existed for
half a century in the UK.

It doesn't matter if the load on the grid is 30GW 50GW or 60GW, wind turbines
are swinging output up and down like a whores drawers, the frequency is low or
high, the voltage at the generator terminals will*always* be controlled towards
a predefined setpoint defined by the manufacturer of the generator maybe 50
years ago.

http://books.google.co.uk/books?id=L7o4TitajRIC&pg=PA11&dq=automatic+voltage +regulator&hl=en&sa=X&ei=TjGCUZ_FDoXy7Abtp4DoDQ&ve d=0CEEQ6AEwAQ#v=onepage&q=automatic%20voltage%20re gulator&f=false


scroll to page 13

Frequency is determined by the speed of rotation. If speed of rotation starts
dropping more steam is admitted It's very similar in response to cruise control
on a relatively flat road.

If more steam is admitted then more fuel has to be burnt to maintain the steam
pressure and temperature.

I have no trouble understanding how intermittency will cause stability
problems. However...

Google won't let me read enough of that book

So the fiddle with the exciter current to maintain a fixed output
voltage, regardless of load? Surely at some point they must run out of
steam...

What actually controls the grid frequency? Is it the tap changing at the
132kV step down?

Yes, the excitation is essentially just for the volts at the generator terminals
(it does more than that but just accept it just sets the volts for now!)

If the generator is not connected to the grid then the governor controlling the
fuelling on a gas turbine or the steam on a coal /oil / nuke will hold the speed
of rotation at exactly 3000rpm (or 1500rpm for a 4 pole generator)

Connected the generator to the grid and the governor will do all it can to
control the speed of rotation to 3000rpm.

If the load is such that the speed of rotation and thus the frequency starts to
fall then more steam is admitted until a steady state is achieved again.

Then grid frequency is determined by the governor set point on all the
generators connected to the grid at that particular moment. In the UK they all
control to 50Hz.

The extra quantity of steam as a percentage of the nominal value at 50Hz for a
grid frequency of say 49.7Hz is say 1%, at 49.5Hz it's 3% at 49Hz it's 6%.
Beyond this point only a certain number of generators and boilers with enough
overfuelling capacity will be able to support the additional steam will be
available. At 48.5Hz the requirements could increase to say 15%. Also as the
frequency drops the speed of the fans and pumps located at the power station
have a lower speed of rotation and output and efficiency drops off. At a certain
point you can't get water back into the boiler quick enough to maintain water
levels and avoid overheating (like running a kettle dry) At that point the
generator trips to protect the boiler, increasing load on the other generators
on the system at that point. So frequency control and generator response are
very important for system stability To protect the integrity of the grid blocks
of load is shed or voltage reduced 'in advance' at set frequency levels to avoid
generators being grossly overloaded and the frequency dropping out of the
statutory limits. Such events are supposed to be something like once in 10 year
events (last one was in 2008 and previously 2003)

The tap changing purely controls the final voltage the consumer sees.

If a tap changer has say 15 taps then tsomething around the middle one should
ultimately result in 240v to the consumer. In an area with more local load it
will be lower heading towards the lower limit. In areas of lighter load it will
be higher, heading towards the upper limit. Industrial load or very lightly
loaded long overhead lines also have an effect on final terminal voltage.

Changes can be made to the tappings on 'local' transformers to correct for new
housing etc, but this is a manual operation, performed offload. The tap changes
on the bulk supply transformers are performed on load, usually automatically and
many times per day.



--

On 03/05/2013 07:10, harry wrote:
The grid frequency is controlled by the speedof the generators. The
only way to change that is change their speed. They are all linked
together no single generator can run faster than the others.
They are locked together as surely as they were all on the same shaft
by the alternating current they generate.

I think not. They can be a few degrees out of phase; those that lead are
putting power in, and those that trail are taking power out. I dare say
the pumped-storage systems do both at different times.

Andy