In article , The Other Mike
scribeth thus
On Thu, 22 Aug 2019 10:04:24 +0100, Martin Brown
wrote:


Looking again at that map and noting her observation that the north
south transmission lines would be absolutely saturated at that peak
usage time

It's not even remotely close to being overloaded with the loss of one
circuit, 28GW national demand with depleted generation in the Midlands
and North being quite normal this time of year. Loading is such that
the loss of a double circuit, twice what happened, is well within the
short term (at least 30 mins even in the highest ambient conditions)
capabilities of the other circuits. The overhead line circuit was
only lost for 20 seconds until auto reclosing.

Isn't the 400 kV grid carrying around half a GW per circuit or is it
more now Mike?..



it struck me that transmission line effects might actually
rebound at the Hornsea windfarm when one of the four main N-S circuits
was broken to clear the fault and the instantaneous power in the grid
had to be split across the remaining three main circuits.

Hornsea might have seen some minor disturbance but the generator /
power park module protection should never be set such that it is
reaching or sensitive to a line fault over 100 miles, two/three lines
and at least three/four HV substations away.

A scenario of two near simultaneous lightning strikes should not be
discounted.


I think it may have been sat on a hair trigger and gave up too easily.
There is a hint in the official report that they "adjusted" things after
the incident to make it more robust wrt transient ms line glitches. I
find it depressing that the executive summary carefully ignored the
timeline and frequency graph evidence in favour of anodyne prose.

The timestamps are accurate within the limitations of MSF or if it
were free running the crystal in an oven in the site radioclock


They must have worked very hard on the form of words they use several
times in the report. Do they think repeating it will make it true?

It's an interim report, it's the best you and OFGEM get to see at the
moment.

It does seem that this DC to AC inverter software circuitry needs some
further though it's not that stable seemingly?

Come to think of it how does the inverter right out in the North see or
know what the grids running at, or does it just ramp up frequency and
see what currents flowing back to blighty?..

Anyone know?..
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

On 22/08/2019 22:29, tony sayer wrote:
It does seem that this DC to AC inverter software circuitry needs some
further though it's not that stable seemingly?

No. And there is a fundamenal point you are missing

It CANNOT be solved just with software.

A temeporaty rid overlaod must be covered either by a loss of load -
load shedding or load reduction - or by an incease of power.

In general load reductiuon and slowering freqeuncy go together in
syncrhonrous motors, and lowering volatges will in general lower to load
with resistive lods. Not so with switched mode power supplies.

So what happens with spinnging nennies is that the rotational inertia os
in fact kinetic energu and that is what represents the increase in power
that will be fed into te grid. As the rotors slow, energy is lost, and
that becomes what keeps the grid up. Until somethinmg else can. Like
openeing the throttle on a coal or nuclear plant

Because steam boilers also represent energy storage too.

The point is this: althoiugh software that reads mains frequency and if
it slows advances the phase of the inverters to feed more power in, are
possible, there IS NO MORE POWER to be had!

Unless you strap lithium bastteries to the DC output of every wind
turbine. Or supercapaciors. Or use a big ****-off rotary inverter. (DC
from wind turbines drives DC motor attached to AC generators attached to
the mains)


More expense. Less profit.






Come to think of it how does the inverter right out in the North see or
know what the grids running at, or does it just ramp up frequency and
see what currents flowing back to blighty?..

Anyone know?..
Phase is the issue.

Before connection the mains frequency and phase is read and the inverter
will connect at slightly leading phase to it. So it draws power. Then
the power in is monitored and the phase adjusted so that full power is
delivered.

So it ramps up phase, not frequency.

The whole grid is phaselocked. If you want to connect a generator to it
you MUST lock phase and advance it a tad until you are feeding it. At
zero phase you are not delivering or taking pwer.

The problem is domestic inverters are set to trip out if the frequency
drops too far as well as having no storage.

They are not serious generators. They are bolt on additions




--
There is nothing a fleet of dispatchable nuclear power plants cannot do
that cannot be done worse and more expensively and with higher carbon
emissions and more adverse environmental impact by adding intermittent
renewable energy.

On 23/08/2019 08:05, The Natural Philosopher wrote:
On 22/08/2019 22:29, tony sayer wrote:
It does seem that this DC to AC inverter software circuitry needs some
further though it's not that stable seemingly?

No. And there is a fundamenal point you are missing

It CANNOT be solved just with software.

A temeporaty rid overlaod must be covered either by a loss of load -
load shedding or load reduction - or by an incease of power.

It could be solved by not putting 100% of everything the wind farm
generated out onto the grid or some local battery storage colocated. The
latter would make some sense since then the large scale DC to AC grid
tie converters could be used for two purposes.

A grid overload can also be handled by allowing the voltage and
frequency to drop. Enough load is resistive that it should balance. It
don't see any reason why an AC to DC converter can't track the phase
right down to the point where conventional spinning kit begins to drop
off. Injecting some power is better than injecting none at all.

In general load reductiuon and slowering freqeuncy go together in
syncrhonrous motors, and lowering volatges will in general lower to load
with resistive lods. Not so with switched mode power supplies.

So what happens with spinnging nennies is that the rotational inertia os
in fact kinetic energu and that is what represents the increase in power
that will be fed into te grid. As the rotors slow, energy is lost, and
that becomesÂ* what keeps the grid up. Until somethinmg else can. Like
openeing the throttle on a coalÂ* or nuclear plant

Because steam boilers also represent energy storage too.

The point is this: althoiugh software that reads mains frequency and if
it slows advances the phase of the inverters to feed more power in, are
possible, there IS NO MORE POWER to be had!

Unless you strap lithium bastteries to the DC output of every wind
turbine. Or supercapaciors. Or use a big ****-off rotary inverter. (DC
from wind turbines drives DC motor attached to AC generators attached to
the mains)

More expense. Less profit.

But enhanced resilience against grid fluctuations. It may be a necessary
thing to add to the larger wind farms so that they can output 110% for a
brief 5 minute period when called upon to do so. Even a minute of extra
reserve might well have been enough to prevent cascade failure.

I have my suspicions something wasn't configured right at Hornsea though
and it tripped because the settings were essentially paranoid. It was a
very long way away from the lightning strike and East Anglia was much
nearer and stayed up as did the toy prototype version of Hornsea.

Come to think of it how does the inverter right out in the North see or
know what the grids running at, or does it just ramp up frequency and
see what currents flowing back to blighty?..

Anyone know?..

Phase is the issue.

Before connection the mains frequency and phase is read and the inverter
will connect at slightly leading phase to it. So it draws power. Then
the power in is monitored and the phase adjusted so that full power is
delivered.

So it ramps up phase, not frequency.

It is a large scale phase locked loop.

The whole grid is phaselocked. If you want to connect a generator to it
you MUST lock phase and advance it a tad until you are feeding it. At
zero phase you are not delivering or taking pwer.

The problem is domestic inverters are set to trip out if the frequency
drops too far as well as having no storage.

They are not serious generators. They are bolt on additions

But I doubt they were a really significant factor in the overall cascade
failure. Most domestic solar PV is rigged to make hot water and pocket
the export FIT for 50% they never export!

--
Regards,
Martin Brown

On 23/08/2019 09:28, Martin Brown wrote:
On 23/08/2019 08:05, The Natural Philosopher wrote:
On 22/08/2019 22:29, tony sayer wrote:
It does seem that this DC to AC inverter software circuitry needs some
further though it's not that stable seemingly?

No. And there is a fundamenal point you are missing

It CANNOT be solved just with software.

A temeporaty rid overlaod must be covered either by a loss of load -
load shedding or load reduction - or by an incease of power.

It could be solved by not putting 100% of everything the wind farm
generated out onto the grid or some local battery storage colocated. The
latter would make some sense since then the large scale DC to AC grid
tie converters could be used for two purposes.

A grid overload can also be handled by allowing the voltage and
frequency to drop. Enough load is resistive that it should balance. It
don't see any reason why an AC to DC converter can't track the phase
right down to the point where conventional spinning kit begins to drop
off. Injecting some power is better than injecting none at all.

In general load reductiuon and slowering freqeuncy go together in
syncrhonrous motors, and lowering volatges will in general lower to
load with resistive lods. Not so with switched mode power supplies.

So what happens with spinnging nennies is that the rotational inertia
os in fact kinetic energu and that is what represents the increase in
power that will be fed into te grid. As the rotors slow, energy is
lost, and that becomesÂ* what keeps the grid up. Until somethinmg else
can. Like openeing the throttle on a coalÂ* or nuclear plant

Because steam boilers also represent energy storage too.

The point is this: althoiugh software that reads mains frequency and
if it slows advances the phase of the inverters to feed more power in,
are possible, there IS NO MORE POWER to be had!

Unless you strap lithium bastteries to the DC output of every wind
turbine. Or supercapaciors. Or use a big ****-off rotary inverter. (DC
from wind turbines drives DC motor attached to AC generators attached
to the mains)

More expense. Less profit.

But enhanced resilience against grid fluctuations. It may be a necessary
thing to add to the larger wind farms so that they can output 110% for a
brief 5 minute period when called upon to do so. Even a minute of extra
reserve might well have been enough to prevent cascade failure.

I have my suspicions something wasn't configured right at Hornsea though
and it tripped because the settings were essentially paranoid. It was a
very long way away from the lightning strike and East Anglia was much
nearer and stayed up as did the toy prototype version of Hornsea.

Come to think of it how does the inverter right out in the North see or
know what the grids running at, or does it just ramp up frequency and
see what currents flowing back to blighty?..

Anyone know?..

Phase is the issue.

Before connection the mains frequency and phase is read and the
inverter will connect at slightly leading phase to it. So it draws
power. Then the power in is monitored and the phase adjusted so that
full power is delivered.

So it ramps up phase, not frequency.

It is a large scale phase locked loop.

The whole grid is phaselocked. If you want to connect a generator to
it you MUST lock phase and advance it a tad until you are feeding it.
At zero phase you are not delivering or taking pwer.

The problem is domestic inverters are set to trip out if the frequency
drops too far as well as having no storage.

They are not serious generators. They are bolt on additions

But I doubt they were a really significant factor in the overall cascade
failure. Most domestic solar PV is rigged to make hot water and pocket
the export FIT for 50% they never export!


More kit less reliability.. more faults that need to be handled.

I used to design fault resilient systems that are still in telephone
exchanges now so I can assure you that you get to a point where you make
the system less reliable.

I ma all for putting batteries in wind farms as long as I don't have to
pay to fix their problems. I would rather build nukes and not have the
problem in the first place.

In article , The Natural Philosopher
scribeth thus
On 22/08/2019 22:29, tony sayer wrote:
It does seem that this DC to AC inverter software circuitry needs some
further though it's not that stable seemingly?

No. And there is a fundamenal point you are missing

It CANNOT be solved just with software.

A temeporaty rid overlaod must be covered either by a loss of load -
load shedding or load reduction - or by an incease of power.

In general load reductiuon and slowering freqeuncy go together in
syncrhonrous motors, and lowering volatges will in general lower to load
with resistive lods. Not so with switched mode power supplies.

So what happens with spinnging nennies is that the rotational inertia os
in fact kinetic energu and that is what represents the increase in power
that will be fed into te grid. As the rotors slow, energy is lost, and
that becomes what keeps the grid up. Until somethinmg else can. Like
openeing the throttle on a coal or nuclear plant

Because steam boilers also represent energy storage too.

The point is this: althoiugh software that reads mains frequency and if
it slows advances the phase of the inverters to feed more power in, are
possible, there IS NO MORE POWER to be had!

Well in that case then perhaps they ought to keep a small amount in
reserve say they have around 100 MW available send as it were 90 MW so
they do have a reserve?.


Unless you strap lithium bastteries to the DC output of every wind
turbine. Or supercapaciors. Or use a big ****-off rotary inverter. (DC
from wind turbines drives DC motor attached to AC generators attached to
the mains)

Ain't happening is it?..


More expense. Less profit.


Come to think of it how does the inverter right out in the North see or
know what the grids running at, or does it just ramp up frequency and
see what currents flowing back to blighty?..

Anyone know?..
Phase is the issue.

Before connection the mains frequency and phase is read and the inverter
will connect at slightly leading phase to it. So it draws power. Then
the power in is monitored and the phase adjusted so that full power is
delivered.

How do they determine what the load side is in an inverter system?

So it ramps up phase, not frequency.


How's it do that without altering the frequency??

The whole grid is phaselocked. If you want to connect a generator to it
you MUST lock phase and advance it a tad until you are feeding it. At
zero phase you are not delivering or taking pwer.

Indeed thats the way its done with alternators but are inverters exactly
the same?..



The problem is domestic inverters are set to trip out if the frequency
drops too far as well as having no storage.

They are not serious generators. They are bolt on additions





--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

More kit less reliability.. more faults that need to be handled.

I used to design fault resilient systems that are still in telephone
exchanges now so I can assure you that you get to a point where you make
the system less reliable.



I ma all for putting batteries in wind farms as long as I don't have to
pay to fix their problems. I would rather build nukes and not have the
problem in the first place.



Yes well thats the worrying bit and its not happening.

In fact we'll still need as much Fossil capacity around as we ever have
to cope with high pressure windless days..

--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

On 23/08/2019 22:00, tony sayer wrote:
In article , The Natural Philosopher
scribeth thus
On 22/08/2019 22:29, tony sayer wrote:
It does seem that this DC to AC inverter software circuitry needs some
further though it's not that stable seemingly?

No. And there is a fundamenal point you are missing

It CANNOT be solved just with software.

A temeporaty rid overlaod must be covered either by a loss of load -
load shedding or load reduction - or by an incease of power.

In general load reductiuon and slowering freqeuncy go together in
syncrhonrous motors, and lowering volatges will in general lower to load
with resistive lods. Not so with switched mode power supplies.

So what happens with spinnging nennies is that the rotational inertia os
in fact kinetic energu and that is what represents the increase in power
that will be fed into te grid. As the rotors slow, energy is lost, and
that becomes what keeps the grid up. Until somethinmg else can. Like
openeing the throttle on a coal or nuclear plant

Because steam boilers also represent energy storage too.

The point is this: althoiugh software that reads mains frequency and if
it slows advances the phase of the inverters to feed more power in, are
possible, there IS NO MORE POWER to be had!

Well in that case then perhaps they ought to keep a small amount in
reserve say they have around 100 MW available send as it were 90 MW so
they do have a reserve?.

Battery would work better.



Unless you strap lithium bastteries to the DC output of every wind
turbine. Or supercapaciors. Or use a big ****-off rotary inverter. (DC
from wind turbines drives DC motor attached to AC generators attached to
the mains)

Ain't happening is it?..

Course not. Costs money.



More expense. Less profit.


Come to think of it how does the inverter right out in the North see or
know what the grids running at, or does it just ramp up frequency and
see what currents flowing back to blighty?..

Anyone know?..
Phase is the issue.

Before connection the mains frequency and phase is read and the inverter
will connect at slightly leading phase to it. So it draws power. Then
the power in is monitored and the phase adjusted so that full power is
delivered.

How do they determine what the load side is in an inverter system?

So it ramps up phase, not frequency.


How's it do that without altering the frequency??

Cmon Tony.

You know the difference bnetween frequency and phase.

If you like the frequency is incereased by a tiny amount for a
millsecond And then goes back to what it was.



The whole grid is phaselocked. If you want to connect a generator to it
you MUST lock phase and advance it a tad until you are feeding it. At
zero phase you are not delivering or taking pwer.

Indeed thats the way its done with alternators but are inverters exactly
the same?..

Er no, Tony. They dont have big coils and spinning iron and slip rings

They have ferrite chokes Fat transistors and software



The problem is domestic inverters are set to trip out if the frequency
drops too far as well as having no storage.

They are not serious generators. They are bolt on additions







--
The New Left are the people they warned you about.