Re: [time-nuts] Line Frequency standard change - Possible ?

[Poul-Henning Kamp]

In message <344e0d5f-e79f-fcfa-eba5-4cf50e047...@comcast.net>, Peter Reilley 
writes:

>If a solar farm also included a battery bank then they would be able to supply
>VAs along with Watts just like a conventional generator.

The large MW size solar farms can already do that but with capacitors rather
than batteries.

I belive Germany has started to change regulations so future solar farms will
have to offer both VA and W to the grid, but I don't know the exact details.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
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Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] Line Frequency standard change - Possible ?

[Poul-Henning Kamp]

In message <006a1c6a-0b2f-16fd-5fef-64352ff14...@earthlink.net>, jimlux writes:
>On 2/9/17 4:03 PM, Poul-Henning Kamp wrote:
>> 
>> In message <63beea7a-f9fc-6e1d-b855-2c7056de3...@earthlink.net>, jimlux 
>> writes:
>>
>>> I think also of the issues from distributed generation - consider a
>>> rooftop solar installation with 20 or so MicroInverters, all "slaved" to
>>> the line.  Just from manufacturing variations, I suspect each
>>> microinverter is a little bit different than the others.
>>
>> Surprising there is almost no variation, because it hurts badly on
>> both your nameplate efficiency and thermal design.
>
>I was thinking about phase stability and "matching" to the grid.. each 
>microinverter (in a short time sense) might have a different phase 
>relationship (which turns into power factor), essentially introducing 
>some "noise" into the system.

At least here in Europe, the eletricity grids were very hostile
to solar initially and therefore the electrical requirements
for approval ended up being very strict, so basically no:  Solar
inverters had to be model citizens noisewise to get installed.

>HV AC lines have exactly the same problem, the switches carry enough 
>energy that "quenching" the arc is by no means assured through the zero 
>crossing.

It is not by any means *assured*, but at least it is *possible*.

Not so with HVDC.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
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Re: [time-nuts] Line Frequency standard change - Possible ?

[Peter Reilley]

They may well be willing to pay for more expensive equipment because they
can make money from it.   large industrial electricity users pay for the VAs
that they use.   Even though they are not energy the utility has to 
supply them.

The utility charges for this service.

If a solar farm also included a battery bank then they would be able to 
supply
VAs along with Watts just like a conventional generator.   With 
batteries solar

farms could contribute to grid stability just like other suppliers.

Pete.



On 2/10/2017 7:43 AM, David wrote:

On Thu, 09 Feb 2017 23:39:24 +, you wrote:


It is harder than it sounds.

Small solar inverters are the best, they an regulate down at milliseconds
notice, and many jurisdictions impose asymetric frequency bands on
them to exploit this.

Big inverters, no matter what you put behind them, get quite a bit
more expensive if they are designed to provide "non-VA" power,
because you suddenly have to run the current both ways in the same
half-cycle.

Nobody wants to pay for that voluntarily, and nobody are particular
keen to cause the first explosion/fire while they get the control-law
debugged.

Imagine how they will scream if they have to pay for fields of big
synchronous motors to be connected.

https://en.wikipedia.org/wiki/Synchronous_condenser
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Re: [time-nuts] Line Frequency standard change - Possible ?

[Didier Juges]

One issue with power factor corrected power supplies is that in the short
term (as a minimum, at the line frequency), they do behave like resistors
(current goes up when voltage goes up) but as they have a slow voltage
regulation loop to provide regulated output, they do behave like constant
power loads to the grid in the long term. The transition between the two
modes of operation is not always smooth and can lead to instabilities when
combined with the generator's response and the line impedance.
I had this particular problem with a 5kW PFC corrected power supply that
was working fine by itself but caused line oscillations when 16 of them
were running in parallel.

On Feb 11, 2017 4:04 AM, "David"  wrote:

> On Thu, 9 Feb 2017 19:06:51 -0500, you wrote:
>
> >One simplistic way to look at all this is that a switcher presents a
> “negative
> >resistance” load. If you drop voltage, current goes up. OCXO’s happen
> >to share this issue. Negative resistances are *not* what most power source
> >guys want in their control loop.
> >
> >Bob
>
> People working with emitter/source followers do not like it either and
> I cannot see the folks using inverters wanting to pay to put big
> resistive heaters across the grid to compensate.
>
> Adding power factor correction to switching power supplies was cheap
> compared adding "negative resistance" correction.
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Re: [time-nuts] Line Frequency standard change - Possible ?

[Magnus Danielson]

Hi,

I know. In practice many of the operators in the US is working together 
to get smarter, share experiences and learn from each other and others.

Good folks.

Cheers,
Magnus

On 02/11/2017 04:08 PM, Bob Camp wrote:

Hi

To be fair to these guys, they have a number of challenges that have nothing to
do with technology. They cross link to other companies and have little control
over how each one operates. Here in the US, we have multiple regulatory
agencies (it happens at the state, federal, and international level).  they all 
are involved
in any change. That makes for a very long and drawn out dance when you fiddle
with this or that. Also, in many cases are the shareholders in the company
who seem to have goals as well ….

Not an easy thing.

Bob


On Feb 11, 2017, at 5:22 AM, Magnus Danielson  
wrote:

Work is already underway to improve the relicense of power grid operations. 
They is smarting up quickly. The PMU/synchrophasor measurements depend on UTC 
and before it can be used full-blown for operation the single point of failure 
needs to be handled.

Cheers,
Magnus

On 02/09/2017 11:19 PM, Peter Reilley wrote:

Isn't this "hard" lock to UTC creating a single point of failure? A
solar burst, an EMP, or
a software error could leave us all in the dark.   After all, smart
inverters could be
programmed to act like big lumps of rotating iron and be compatible with
the current
system.

Pete.

On 2/9/2017 4:31 PM, Poul-Henning Kamp wrote:


In message
<4fbdd81ddf04fc46870db1b9a747269202916...@mbx032-e1-va-8.exch032.ser
verpod.net>, "Thomas D. Erb" writes:


I was wondering if anyone was familiar with this proposal, is this
a uncoupling of line frequency from a time standard ?

The interesting thing about this is that all research and experiments
(for instance on the danish island Bornholm) indicates that the only
way we stand any chance of keeping future AC grids under control in the
medium term is to lock the frequency *hard* to UTC.

Its a very interesting topic.

In the traditional AC grid power is produced by big heavy lumps of
rotating iron.  This couples the grid frequency tightly to the
power-balance of the grid:  If the load increases, the generators
magnetic field drags harder slowing the rotor, lowering the frequency
and vice versa.

This makes the grid frequency a "proxy signal" for the power balance,
and very usefully so, because it travels well and noiselessly through
the entire AC grid.

The only other possible "balance signal" is the voltage, and it
suffers from a host of noise mechanisms, from bad contacts and
lightning strikes to temperature, but worst of all, it takes double
hit when you start big induction motors, thus oversignalling the
power deficit.

Where the frequency as "proxy" for grid balance reacts and can
be used to steering on a 100msec timescale, you need to average
a voltage "proxy" signal for upwards of 20 seconds to get the
noise down to level where you don't introduce instability.

The big picture problem is that we are rapidly retiring the rotating
iron, replacing it with switch-mode converters which do not "couple"
the frequency to power balance.

For instance HVDC/AC converters, solar panel farms, and increasingly
wind generators, do not try to drag down the frequency when they
cannot produce more or drag the frequency up when they can produce
more power, they just faithfully track whatever frequency all the
rotating lumps of iron have agreed on.

As more and more rotating iron gets retired, the grid frequency
eventually becomes useless as a "proxy-signal" for grid balance.

Informal and usually undocumented experiments have already shown
that areas of grids which previously were able to run in "island"
mode, are no longer able to do so, due to shortage of rotating iron.

One way we have found to make the voltage a usable fast-reacting
proxy for grid power-balance, is to lock the frequency to GNSS at
1e-5 s level at all major producers, which is trivial for all the
switch-mode kit, and incredibly hard and energy-inefficient for the
rotating iron producers.

The other way is to cut the big grids into smaller grids with HVDC
connections to decouple the frequencies, which allows us to relax
the frequency tolerance for each of these subgrids substantially.

This solution gets even better if you load the HVDC up with capacitance
to act as a short time buffers, but the consequences in terms of
short circuit energy are ... spectacular?

(It is already bad enough with cable capacitance in long HVDC
connections, do the math on 15nF/Km and 100.000 kV yourself.)

All these issues are compounded by the fact that the "50/60Hz or
bust" mentality has been tatooed on the nose of five generations
of HV engineers, to such an extent that many of them are totally
incapable of even imagining anything else, and they all just "know"
that DC is "impossible".

In the long term, HVDC is going to take over, because it beats HVAC
big time on long 

Re: [time-nuts] Line Frequency standard change - Possible ?

[Poul-Henning Kamp]

In message <9fd9beca-832a-4c38-9799-4a31625f7...@n1k.org>, Bob Camp writes:

>Not an easy thing.

Not even close, which is precisely why the "50/60 Hz or bust" mindset
doesn't work any longer.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] Line Frequency standard change - Possible ?

[Bob Camp]

Hi

To be fair to these guys, they have a number of challenges that have nothing to
do with technology. They cross link to other companies and have little control 
over how each one operates. Here in the US, we have multiple regulatory 
agencies (it happens at the state, federal, and international level).  they all 
are involved 
in any change. That makes for a very long and drawn out dance when you fiddle
with this or that. Also, in many cases are the shareholders in the company 
who seem to have goals as well ….

Not an easy thing.

Bob 

> On Feb 11, 2017, at 5:22 AM, Magnus Danielson  
> wrote:
> 
> Work is already underway to improve the relicense of power grid operations. 
> They is smarting up quickly. The PMU/synchrophasor measurements depend on UTC 
> and before it can be used full-blown for operation the single point of 
> failure needs to be handled.
> 
> Cheers,
> Magnus
> 
> On 02/09/2017 11:19 PM, Peter Reilley wrote:
>> Isn't this "hard" lock to UTC creating a single point of failure? A
>> solar burst, an EMP, or
>> a software error could leave us all in the dark.   After all, smart
>> inverters could be
>> programmed to act like big lumps of rotating iron and be compatible with
>> the current
>> system.
>> 
>> Pete.
>> 
>> On 2/9/2017 4:31 PM, Poul-Henning Kamp wrote:
>>> 
>>> In message
>>> <4fbdd81ddf04fc46870db1b9a747269202916...@mbx032-e1-va-8.exch032.ser
>>> verpod.net>, "Thomas D. Erb" writes:
>>> 
 I was wondering if anyone was familiar with this proposal, is this
 a uncoupling of line frequency from a time standard ?
>>> The interesting thing about this is that all research and experiments
>>> (for instance on the danish island Bornholm) indicates that the only
>>> way we stand any chance of keeping future AC grids under control in the
>>> medium term is to lock the frequency *hard* to UTC.
>>> 
>>> Its a very interesting topic.
>>> 
>>> In the traditional AC grid power is produced by big heavy lumps of
>>> rotating iron.  This couples the grid frequency tightly to the
>>> power-balance of the grid:  If the load increases, the generators
>>> magnetic field drags harder slowing the rotor, lowering the frequency
>>> and vice versa.
>>> 
>>> This makes the grid frequency a "proxy signal" for the power balance,
>>> and very usefully so, because it travels well and noiselessly through
>>> the entire AC grid.
>>> 
>>> The only other possible "balance signal" is the voltage, and it
>>> suffers from a host of noise mechanisms, from bad contacts and
>>> lightning strikes to temperature, but worst of all, it takes double
>>> hit when you start big induction motors, thus oversignalling the
>>> power deficit.
>>> 
>>> Where the frequency as "proxy" for grid balance reacts and can
>>> be used to steering on a 100msec timescale, you need to average
>>> a voltage "proxy" signal for upwards of 20 seconds to get the
>>> noise down to level where you don't introduce instability.
>>> 
>>> The big picture problem is that we are rapidly retiring the rotating
>>> iron, replacing it with switch-mode converters which do not "couple"
>>> the frequency to power balance.
>>> 
>>> For instance HVDC/AC converters, solar panel farms, and increasingly
>>> wind generators, do not try to drag down the frequency when they
>>> cannot produce more or drag the frequency up when they can produce
>>> more power, they just faithfully track whatever frequency all the
>>> rotating lumps of iron have agreed on.
>>> 
>>> As more and more rotating iron gets retired, the grid frequency
>>> eventually becomes useless as a "proxy-signal" for grid balance.
>>> 
>>> Informal and usually undocumented experiments have already shown
>>> that areas of grids which previously were able to run in "island"
>>> mode, are no longer able to do so, due to shortage of rotating iron.
>>> 
>>> One way we have found to make the voltage a usable fast-reacting
>>> proxy for grid power-balance, is to lock the frequency to GNSS at
>>> 1e-5 s level at all major producers, which is trivial for all the
>>> switch-mode kit, and incredibly hard and energy-inefficient for the
>>> rotating iron producers.
>>> 
>>> The other way is to cut the big grids into smaller grids with HVDC
>>> connections to decouple the frequencies, which allows us to relax
>>> the frequency tolerance for each of these subgrids substantially.
>>> 
>>> This solution gets even better if you load the HVDC up with capacitance
>>> to act as a short time buffers, but the consequences in terms of
>>> short circuit energy are ... spectacular?
>>> 
>>> (It is already bad enough with cable capacitance in long HVDC
>>> connections, do the math on 15nF/Km and 100.000 kV yourself.)
>>> 
>>> All these issues are compounded by the fact that the "50/60Hz or
>>> bust" mentality has been tatooed on the nose of five generations
>>> of HV engineers, to such an extent that many of them are totally
>>> incapable of even imagining anything else, and they all 

Re: [time-nuts] Line Frequency standard change - Possible ?

[Magnus Danielson]

Work is already underway to improve the relicense of power grid 
operations. They is smarting up quickly. The PMU/synchrophasor 
measurements depend on UTC and before it can be used full-blown for 
operation the single point of failure needs to be handled.


Cheers,
Magnus

On 02/09/2017 11:19 PM, Peter Reilley wrote:

Isn't this "hard" lock to UTC creating a single point of failure? A
solar burst, an EMP, or
a software error could leave us all in the dark.   After all, smart
inverters could be
programmed to act like big lumps of rotating iron and be compatible with
the current
system.

Pete.

On 2/9/2017 4:31 PM, Poul-Henning Kamp wrote:


In message
<4fbdd81ddf04fc46870db1b9a747269202916...@mbx032-e1-va-8.exch032.ser
verpod.net>, "Thomas D. Erb" writes:


I was wondering if anyone was familiar with this proposal, is this
a uncoupling of line frequency from a time standard ?

The interesting thing about this is that all research and experiments
(for instance on the danish island Bornholm) indicates that the only
way we stand any chance of keeping future AC grids under control in the
medium term is to lock the frequency *hard* to UTC.

Its a very interesting topic.

In the traditional AC grid power is produced by big heavy lumps of
rotating iron.  This couples the grid frequency tightly to the
power-balance of the grid:  If the load increases, the generators
magnetic field drags harder slowing the rotor, lowering the frequency
and vice versa.

This makes the grid frequency a "proxy signal" for the power balance,
and very usefully so, because it travels well and noiselessly through
the entire AC grid.

The only other possible "balance signal" is the voltage, and it
suffers from a host of noise mechanisms, from bad contacts and
lightning strikes to temperature, but worst of all, it takes double
hit when you start big induction motors, thus oversignalling the
power deficit.

Where the frequency as "proxy" for grid balance reacts and can
be used to steering on a 100msec timescale, you need to average
a voltage "proxy" signal for upwards of 20 seconds to get the
noise down to level where you don't introduce instability.

The big picture problem is that we are rapidly retiring the rotating
iron, replacing it with switch-mode converters which do not "couple"
the frequency to power balance.

For instance HVDC/AC converters, solar panel farms, and increasingly
wind generators, do not try to drag down the frequency when they
cannot produce more or drag the frequency up when they can produce
more power, they just faithfully track whatever frequency all the
rotating lumps of iron have agreed on.

As more and more rotating iron gets retired, the grid frequency
eventually becomes useless as a "proxy-signal" for grid balance.

Informal and usually undocumented experiments have already shown
that areas of grids which previously were able to run in "island"
mode, are no longer able to do so, due to shortage of rotating iron.

One way we have found to make the voltage a usable fast-reacting
proxy for grid power-balance, is to lock the frequency to GNSS at
1e-5 s level at all major producers, which is trivial for all the
switch-mode kit, and incredibly hard and energy-inefficient for the
rotating iron producers.

The other way is to cut the big grids into smaller grids with HVDC
connections to decouple the frequencies, which allows us to relax
the frequency tolerance for each of these subgrids substantially.

This solution gets even better if you load the HVDC up with capacitance
to act as a short time buffers, but the consequences in terms of
short circuit energy are ... spectacular?

(It is already bad enough with cable capacitance in long HVDC
connections, do the math on 15nF/Km and 100.000 kV yourself.)

All these issues are compounded by the fact that the "50/60Hz or
bust" mentality has been tatooed on the nose of five generations
of HV engineers, to such an extent that many of them are totally
incapable of even imagining anything else, and they all just "know"
that DC is "impossible".

In the long term, HVDC is going to take over, because it beats HVAC
big time on long connections, and it is only a matter of getting
semiconductors into shape before that happens.  That however,
is by no means a trivial task:  It's all about silicon purity.




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Re: [time-nuts] Line Frequency standard change - Possible ?

[Magnus Danielson]

Hi Jim,

On 02/09/2017 11:39 PM, jimlux wrote:

On 2/9/17 1:31 PM, Poul-Henning Kamp wrote:


In message
<4fbdd81ddf04fc46870db1b9a747269202916...@mbx032-e1-va-8.exch032.ser
verpod.net>, "Thomas D. Erb" writes:


I was wondering if anyone was familiar with this proposal, is this
a uncoupling of line frequency from a time standard ?


The interesting thing about this is that all research and experiments
(for instance on the danish island Bornholm) indicates that the only
way we stand any chance of keeping future AC grids under control in the
medium term is to lock the frequency *hard* to UTC.

Its a very interesting topic.




I think also of the issues from distributed generation - consider a
rooftop solar installation with 20 or so MicroInverters, all "slaved" to
the line.  Just from manufacturing variations, I suspect each
microinverter is a little bit different than the others.


By code these needs to feed in phase with the line, meaning they do not 
contribute with reactance as if it was rotating iron.


While trying to be "safe" is does not contribute to stability, only to 
power.


Cheers,
Magnus
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Re: [time-nuts] Line Frequency standard change - Possible ?

[David]

On Thu, 9 Feb 2017 17:19:49 -0500, you wrote:

>Isn't this "hard" lock to UTC creating a single point of failure? A 
>solar burst, an EMP, or
>a software error could leave us all in the dark.   After all, smart 
>inverters could be
>programmed to act like big lumps of rotating iron and be compatible with 
>the current
>system.
>
>Pete.

I have the same concern.  I am dubious of tying power grid reliability
to GPS reliability and doubly so in a threat environment which
includes hostile actors.  And if an alternative more reliable timing
standard was used then why use GPS at all?

Inverters lack the overload capability and resistance of rotating iron
unless they are overbuilt in which case they would be uneconomical.
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Re: [time-nuts] Line Frequency standard change - Possible ?

[David]

On Thu, 9 Feb 2017 19:06:51 -0500, you wrote:

>One simplistic way to look at all this is that a switcher presents a “negative
>resistance” load. If you drop voltage, current goes up. OCXO’s happen 
>to share this issue. Negative resistances are *not* what most power source
>guys want in their control loop.
>
>Bob

People working with emitter/source followers do not like it either and
I cannot see the folks using inverters wanting to pay to put big
resistive heaters across the grid to compensate.

Adding power factor correction to switching power supplies was cheap
compared adding "negative resistance" correction.
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Re: [time-nuts] Line Frequency standard change - Possible ?

[David]

On Thu, 09 Feb 2017 23:39:24 +, you wrote:

>It is harder than it sounds.
>
>Small solar inverters are the best, they an regulate down at milliseconds
>notice, and many jurisdictions impose asymetric frequency bands on
>them to exploit this.
>
>Big inverters, no matter what you put behind them, get quite a bit
>more expensive if they are designed to provide "non-VA" power,
>because you suddenly have to run the current both ways in the same
>half-cycle.
>
>Nobody wants to pay for that voluntarily, and nobody are particular
>keen to cause the first explosion/fire while they get the control-law
>debugged.

Imagine how they will scream if they have to pay for fields of big
synchronous motors to be connected.

https://en.wikipedia.org/wiki/Synchronous_condenser
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Re: [time-nuts] Line Frequency standard change - Possible ?

[Poul-Henning Kamp]

In message <043966d4-def4-4bc4-ba9d-ec46070fd...@comcast.net>, Peter Reilley wr
ites:

>Even in the old days a lot of devices were constant load, independent of 
>voltage (within reason).
>Anything regulated such as electric heat, electric hot water, and 
>refrigerators are constant load.

Constant over the long term (hours), but not in the short term (seconds)
where grid stability is most important.

>Utilities found that dropping the voltage was not very effective at 
>shedding load in emergency
>situations.

No, it's no use for shedding load, but keeping things nice and
stable is much easier with a load which converges on your
target parameters, than with a load which diverges from it.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] Line Frequency standard change - Possible ?

[Peter Reilley]

Even in the old days a lot of devices were constant load, independent of 
voltage (within reason).
Anything regulated such as electric heat, electric hot water, and 
refrigerators are constant load.
Synchronous motors (most motors) are frequency dependent.   They do get 
less efficient at lower
voltages because their slip speed increases but that is a small percent 
of their running speed.
Non-synchronous motors are often speed regulated so they are constant 
load.   Electric transportation

is constant load.

I am sure that I could come up with more examples.

Utilities found that dropping the voltage was not very effective at 
shedding load in emergency

situations.   However, rolling blackouts do work very well.

Pete.

On 2/9/2017 6:55 PM, Poul-Henning Kamp wrote:


In message 

Re: [time-nuts] Line Frequency standard change - Possible ?

[jimlux]

On 2/9/17 4:03 PM, Poul-Henning Kamp wrote:


In message <63beea7a-f9fc-6e1d-b855-2c7056de3...@earthlink.net>, jimlux writes:


I think also of the issues from distributed generation - consider a
rooftop solar installation with 20 or so MicroInverters, all "slaved" to
the line.  Just from manufacturing variations, I suspect each
microinverter is a little bit different than the others.


Surprising there is almost no variation, because it hurts badly on
both your nameplate efficiency and thermal design.


I was thinking about phase stability and "matching" to the grid.. each 
microinverter (in a short time sense) might have a different phase 
relationship (which turns into power factor), essentially introducing 
some "noise" into the system.



But shorts are another matter:  They are so much easier to deal
with when you have regular zero-crossings a hundred times a second:
HVDC shorts are explosions which doesn't end until you've used up
all the energy.



HV AC lines have exactly the same problem, the switches carry enough 
energy that "quenching" the arc is by no means assured through the zero 
crossing. If nothing else, inductance in the system (e.g. transmission 
lines) insures that the voltage zero isn't at the same time as the 
current zero.


There was a fascinating article about this in Scientific American back 
in the 70s (Jan 1971, there was a picture of an airblast circuit breaker 
on the cover).  There's also a good description in IEEE Proceedings in 
the article on Vacuum switching

http://ieeexplore.ieee.org/document/1451144/
Aug 73



The pacific dc intertie is a lot more than 10m apart, so it's probably
lower, but still..  14 uF @ 1MV is a bunch o'Joules. (about 14 Mj)
Fortunately, there's a fairly large series L also to slow down the
transient.


Yes, it slows down the front flank, on the other hand, once you get
the arc going, with DC that L really keeps it going for a long time.


But 14 MJ isn't all that much energy in practical terms.. about a half 
liter of gasoline (most fuels are around 50MJ/kg), or 3kg of high explosive.


yeah, 3kg of HE does a fair amount of damage, but it is localized (in a 
10s of meters sense).


When the distribution transformer near my house blew up, I suspect that 
a lot more energy was dissipated.. it was a 100kVA unit in a underground 
vault, and it blew the 2x2m concrete vault lid 10s of meters away.


In reality, there's probably more stored energy in the L of the 
transmission line than in the C.  A quick back of hte envelope: 1 
uH/meter is 1mH/km, so we're looking at 3000A in 1.3H.  Oh, that's just 
about the same as the energy in the C.  about 12 MJ.





The difference in practice is that a HVAC short leaves a burn-mark
on the metal parts, HVDC solidly welds them together if it doesn't
outright melt them.




For big lines, the melting is "explosive" and doesn't leave much solid 
metal behind.



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Re: [time-nuts] Line Frequency standard change - Possible ?

[Bob Camp]

Hi

> On Feb 9, 2017, at 6:55 PM, Poul-Henning Kamp  wrote:
> 
> 
> In message 
> 

Re: [time-nuts] Line Frequency standard change - Possible ?

[Poul-Henning Kamp]

In message <63beea7a-f9fc-6e1d-b855-2c7056de3...@earthlink.net>, jimlux writes:

>I think also of the issues from distributed generation - consider a 
>rooftop solar installation with 20 or so MicroInverters, all "slaved" to 
>the line.  Just from manufacturing variations, I suspect each 
>microinverter is a little bit different than the others.

Surprising there is almost no variation, because it hurts badly on
both your nameplate efficiency and thermal design.

>> This solution gets even better if you load the HVDC up with capacitance
>> to act as a short time buffers, but the consequences in terms of
>> short circuit energy are ... spectacular?
>
>yeah, but that's a "solvable" problem in terms of circuit breaker 
>design. We've all seen the Lugo substation video (not DC, but big AC 
>with the suppression disabled so it can "pull an arc" for test)

Yes, that's the easy case, and good old dynamite based emergency
switches work too.

But shorts are another matter:  They are so much easier to deal
with when you have regular zero-crossings a hundred times a second:
HVDC shorts are explosions which doesn't end until you've used up
all the energy.

>The pacific dc intertie is a lot more than 10m apart, so it's probably 
>lower, but still..  14 uF @ 1MV is a bunch o'Joules. (about 14 Mj) 
>Fortunately, there's a fairly large series L also to slow down the 
>transient.

Yes, it slows down the front flank, on the other hand, once you get
the arc going, with DC that L really keeps it going for a long time.

The difference in practice is that a HVAC short leaves a burn-mark
on the metal parts, HVDC solidly welds them together if it doesn't
outright melt them.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
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Re: [time-nuts] Line Frequency standard change - Possible ?

[Poul-Henning Kamp]

In message <28842754-1752-40e8-b3d5-f486a5da9...@n1k.org>, Bob Camp writes:

>> to such an extent that many of them are totally
>> incapable of even imagining anything else, and they all just "know"
>> that DC is "impossible”.
>
>Except we’ve had HVDC distribution running around for many decades
>and it seems to work quite well. Indeed that’s your point here. 

But if you look at the organization and regulation systems, the
HVDC end stations are not treated as transmission but as power
plants.

>… or silicon carbide purity or something even more weird and (so far)
>poorly understood.

The SiC hypers overlooked the C14 isotope beta-decay ionization
problem, and the anti-proliferation clampdown on ALIS have taken
away any hope producing C14 depleted raw materials.  And even if
you did that, cosmic radiation would bring back enough C14 to be
trouble over the lifetime of the devices.

According to people in the HVDC electronics (if you can call it that)
business, we can build any of the devices we need from current
high purity semiconductors, but the costs need to come down.


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
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Re: [time-nuts] Line Frequency standard change - Possible ?

[Poul-Henning Kamp]

In message 

Re: [time-nuts] Line Frequency standard change - Possible ?

[Bob Camp]

Hi

If you are talking about big power gizmos, putting a GPSDO on them is pretty 
simple 
cost and system wise. Given the fact that 10 ns sync is not required, the 
actual implementation 
might be pretty cheap.

Bob


> On Feb 9, 2017, at 5:19 PM, Peter Reilley  wrote:
> 
> Isn't this "hard" lock to UTC creating a single point of failure? A solar 
> burst, an EMP, or
> a software error could leave us all in the dark.   After all, smart inverters 
> could be
> programmed to act like big lumps of rotating iron and be compatible with the 
> current
> system.
> 
> Pete.
> 
> On 2/9/2017 4:31 PM, Poul-Henning Kamp wrote:
>> 
>> In message 
>> <4fbdd81ddf04fc46870db1b9a747269202916...@mbx032-e1-va-8.exch032.ser
>> verpod.net>, "Thomas D. Erb" writes:
>> 
>>> I was wondering if anyone was familiar with this proposal, is this
>>> a uncoupling of line frequency from a time standard ?
>> The interesting thing about this is that all research and experiments
>> (for instance on the danish island Bornholm) indicates that the only
>> way we stand any chance of keeping future AC grids under control in the
>> medium term is to lock the frequency *hard* to UTC.
>> 
>> Its a very interesting topic.
>> 
>> In the traditional AC grid power is produced by big heavy lumps of
>> rotating iron.  This couples the grid frequency tightly to the
>> power-balance of the grid:  If the load increases, the generators
>> magnetic field drags harder slowing the rotor, lowering the frequency
>> and vice versa.
>> 
>> This makes the grid frequency a "proxy signal" for the power balance,
>> and very usefully so, because it travels well and noiselessly through
>> the entire AC grid.
>> 
>> The only other possible "balance signal" is the voltage, and it
>> suffers from a host of noise mechanisms, from bad contacts and
>> lightning strikes to temperature, but worst of all, it takes double
>> hit when you start big induction motors, thus oversignalling the
>> power deficit.
>> 
>> Where the frequency as "proxy" for grid balance reacts and can
>> be used to steering on a 100msec timescale, you need to average
>> a voltage "proxy" signal for upwards of 20 seconds to get the
>> noise down to level where you don't introduce instability.
>> 
>> The big picture problem is that we are rapidly retiring the rotating
>> iron, replacing it with switch-mode converters which do not "couple"
>> the frequency to power balance.
>> 
>> For instance HVDC/AC converters, solar panel farms, and increasingly
>> wind generators, do not try to drag down the frequency when they
>> cannot produce more or drag the frequency up when they can produce
>> more power, they just faithfully track whatever frequency all the
>> rotating lumps of iron have agreed on.
>> 
>> As more and more rotating iron gets retired, the grid frequency
>> eventually becomes useless as a "proxy-signal" for grid balance.
>> 
>> Informal and usually undocumented experiments have already shown
>> that areas of grids which previously were able to run in "island"
>> mode, are no longer able to do so, due to shortage of rotating iron.
>> 
>> One way we have found to make the voltage a usable fast-reacting
>> proxy for grid power-balance, is to lock the frequency to GNSS at
>> 1e-5 s level at all major producers, which is trivial for all the
>> switch-mode kit, and incredibly hard and energy-inefficient for the
>> rotating iron producers.
>> 
>> The other way is to cut the big grids into smaller grids with HVDC
>> connections to decouple the frequencies, which allows us to relax
>> the frequency tolerance for each of these subgrids substantially.
>> 
>> This solution gets even better if you load the HVDC up with capacitance
>> to act as a short time buffers, but the consequences in terms of
>> short circuit energy are ... spectacular?
>> 
>> (It is already bad enough with cable capacitance in long HVDC
>> connections, do the math on 15nF/Km and 100.000 kV yourself.)
>> 
>> All these issues are compounded by the fact that the "50/60Hz or
>> bust" mentality has been tatooed on the nose of five generations
>> of HV engineers, to such an extent that many of them are totally
>> incapable of even imagining anything else, and they all just "know"
>> that DC is "impossible".
>> 
>> In the long term, HVDC is going to take over, because it beats HVAC
>> big time on long connections, and it is only a matter of getting
>> semiconductors into shape before that happens.  That however,
>> is by no means a trivial task:  It's all about silicon purity.
>> 
>> 
> 
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Re: [time-nuts] Line Frequency standard change - Possible ?

[Poul-Henning Kamp]

In message , Peter Reilley wr
ites:

>Isn't this "hard" lock to UTC creating a single point of failure? A 
>solar burst, an EMP, or
>a software error could leave us all in the dark.

Well, to be honest, all of those things would wreck havoc with
any big grid...

The bigger concern is what happens when the three GPS receivers
on your 1GW nuclear block disagree 10 milliseconds...


>After all, smart inverters could be
>programmed to act like big lumps of rotating iron and be compatible with 
>the current system.

It is harder than it sounds.

Small solar inverters are the best, they an regulate down at milliseconds
notice, and many jurisdictions impose asymetric frequency bands on
them to exploit this.

Big inverters, no matter what you put behind them, get quite a bit
more expensive if they are designed to provide "non-VA" power,
because you suddenly have to run the current both ways in the same
half-cycle.

Nobody wants to pay for that voluntarily, and nobody are particular
keen to cause the first explosion/fire while they get the control-law
debugged.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
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Re: [time-nuts] Line Frequency standard change - Possible ?

[Bob Camp]

> On Feb 9, 2017, at 4:31 PM, Poul-Henning Kamp  wrote:
> 
> 
> In message 
> <4fbdd81ddf04fc46870db1b9a747269202916...@mbx032-e1-va-8.exch032.ser
> verpod.net>, "Thomas D. Erb" writes:
> 
>> I was wondering if anyone was familiar with this proposal, is this
>> a uncoupling of line frequency from a time standard ?
> 
> The interesting thing about this is that all research and experiments
> (for instance on the danish island Bornholm) indicates that the only
> way we stand any chance of keeping future AC grids under control in the
> medium term is to lock the frequency *hard* to UTC.
> 
> Its a very interesting topic.
> 
> In the traditional AC grid power is produced by big heavy lumps of
> rotating iron.  This couples the grid frequency tightly to the
> power-balance of the grid:  If the load increases, the generators
> magnetic field drags harder slowing the rotor, lowering the frequency
> and vice versa.
> 
> This makes the grid frequency a "proxy signal" for the power balance,
> and very usefully so, because it travels well and noiselessly through
> the entire AC grid.
> 
> The only other possible "balance signal" is the voltage, and it
> suffers from a host of noise mechanisms, from bad contacts and
> lightning strikes to temperature, but worst of all, it takes double
> hit when you start big induction motors, thus oversignalling the
> power deficit.
> 
> Where the frequency as "proxy" for grid balance reacts and can
> be used to steering on a 100msec timescale, you need to average
> a voltage "proxy" signal for upwards of 20 seconds to get the
> noise down to level where you don't introduce instability.
> 
> The big picture problem is that we are rapidly retiring the rotating
> iron, replacing it with switch-mode converters which do not "couple"
> the frequency to power balance.
> 
> For instance HVDC/AC converters, solar panel farms, and increasingly
> wind generators, do not try to drag down the frequency when they
> cannot produce more or drag the frequency up when they can produce
> more power, they just faithfully track whatever frequency all the
> rotating lumps of iron have agreed on.
> 
> As more and more rotating iron gets retired, the grid frequency
> eventually becomes useless as a "proxy-signal" for grid balance.
> 
> Informal and usually undocumented experiments have already shown
> that areas of grids which previously were able to run in "island"
> mode, are no longer able to do so, due to shortage of rotating iron.
> 
> One way we have found to make the voltage a usable fast-reacting
> proxy for grid power-balance, is to lock the frequency to GNSS at
> 1e-5 s level at all major producers, which is trivial for all the
> switch-mode kit, and incredibly hard and energy-inefficient for the
> rotating iron producers.
> 
> The other way is to cut the big grids into smaller grids with HVDC
> connections to decouple the frequencies, which allows us to relax
> the frequency tolerance for each of these subgrids substantially.
> 
> This solution gets even better if you load the HVDC up with capacitance
> to act as a short time buffers, but the consequences in terms of
> short circuit energy are ... spectacular?
> 
> (It is already bad enough with cable capacitance in long HVDC
> connections, do the math on 15nF/Km and 100.000 kV yourself.)
> 
> All these issues are compounded by the fact that the "50/60Hz or
> bust" mentality has been tatooed on the nose of five generations
> of HV engineers,

Umm… you left out the 25Hz power system that runs across the 
road just a few miles from here :) Some of these ideas take a *long* time
to die. It’s been happily doing it’s thing for over a century. 

> to such an extent that many of them are totally
> incapable of even imagining anything else, and they all just "know"
> that DC is "impossible”.

Except we’ve had HVDC distribution running around for many decades
and it seems to work quite well. Indeed that’s your point here. 

> 
> In the long term, HVDC is going to take over, because it beats HVAC
> big time on long connections, and it is only a matter of getting
> semiconductors into shape before that happens.  That however,
> is by no means a trivial task:  It's all about silicon purity.

… or silicon carbide purity or something even more weird and (so far)
poorly understood.

Bob

> 
> 
> -- 
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] Line Frequency standard change - Possible ?

[jimlux]

On 2/9/17 1:31 PM, Poul-Henning Kamp wrote:


In message <4fbdd81ddf04fc46870db1b9a747269202916...@mbx032-e1-va-8.exch032.ser
verpod.net>, "Thomas D. Erb" writes:


I was wondering if anyone was familiar with this proposal, is this
a uncoupling of line frequency from a time standard ?


The interesting thing about this is that all research and experiments
(for instance on the danish island Bornholm) indicates that the only
way we stand any chance of keeping future AC grids under control in the
medium term is to lock the frequency *hard* to UTC.

Its a very interesting topic.




I think also of the issues from distributed generation - consider a 
rooftop solar installation with 20 or so MicroInverters, all "slaved" to 
the line.  Just from manufacturing variations, I suspect each 
microinverter is a little bit different than the others.







This solution gets even better if you load the HVDC up with capacitance
to act as a short time buffers, but the consequences in terms of
short circuit energy are ... spectacular?


yeah, but that's a "solvable" problem in terms of circuit breaker 
design. We've all seen the Lugo substation video (not DC, but big AC 
with the suppression disabled so it can "pull an arc" for test)


The Pacific Intertie is 1MV at 3000A for 1360 km.

2 bundled conductors 10m apart is about 10pF/m, or 10nF/km  (vague 
recollection from somewhere)


The pacific dc intertie is a lot more than 10m apart, so it's probably 
lower, but still..  14 uF @ 1MV is a bunch o'Joules. (about 14 Mj) 
Fortunately, there's a fairly large series L also to slow down the 
transient.


In comparison, the fairly large Marx at the Deutsches Museum is 33 nF at 
1.2 MV..





(It is already bad enough with cable capacitance in long HVDC
connections, do the math on 15nF/Km and 100.000 kV yourself.)



underground cables have substantially higher capacitance.. I think your 
number is a "suspended in air" value.


I'm not sure that's as big a deal..  the stored energy in cables (as 
opposed to overhead lines) is also a big problem with AC distribution.. 
transient settling times are enormous and it leads to big stability 
issues.  Pretty much, you can use long AC cables only for unidirectional 
power transfer "source to load" not for "source interconnect" because of 
the stability problems (with that rotating iron)


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Re: [time-nuts] Line Frequency standard change - Possible ?

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 9 February 2017 at 21:31, Poul-Henning Kamp  wrote:

>
> The only other possible "balance signal" is the voltage, and it
> suffers from a host of noise mechanisms, from bad contacts and
> lightning strikes to temperature, but worst of all, it takes double
> hit when you start big induction motors, thus oversignalling the
> power deficit.
>
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20

I'm not sure what you mean by "balance signal" here. But I was chatting to
a friend, who used to control generators at two power stations in the UK -
one coal, the other nuclear. It is fairly obvious that the power put into
the grid must equal the power consumed, plus losses. What is also true, and
less obvious, is that the V*A must balance too. He said that he would
receive a call from the CEGB, saying they wanted X Watts, and a power
factor of Y.


Dave
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Re: [time-nuts] Line Frequency standard change - Possible ?

[Peter Reilley]

Isn't this "hard" lock to UTC creating a single point of failure? A 
solar burst, an EMP, or
a software error could leave us all in the dark.   After all, smart 
inverters could be
programmed to act like big lumps of rotating iron and be compatible with 
the current

system.

Pete.

On 2/9/2017 4:31 PM, Poul-Henning Kamp wrote:


In message <4fbdd81ddf04fc46870db1b9a747269202916...@mbx032-e1-va-8.exch032.ser
verpod.net>, "Thomas D. Erb" writes:


I was wondering if anyone was familiar with this proposal, is this
a uncoupling of line frequency from a time standard ?

The interesting thing about this is that all research and experiments
(for instance on the danish island Bornholm) indicates that the only
way we stand any chance of keeping future AC grids under control in the
medium term is to lock the frequency *hard* to UTC.

Its a very interesting topic.

In the traditional AC grid power is produced by big heavy lumps of
rotating iron.  This couples the grid frequency tightly to the
power-balance of the grid:  If the load increases, the generators
magnetic field drags harder slowing the rotor, lowering the frequency
and vice versa.

This makes the grid frequency a "proxy signal" for the power balance,
and very usefully so, because it travels well and noiselessly through
the entire AC grid.

The only other possible "balance signal" is the voltage, and it
suffers from a host of noise mechanisms, from bad contacts and
lightning strikes to temperature, but worst of all, it takes double
hit when you start big induction motors, thus oversignalling the
power deficit.

Where the frequency as "proxy" for grid balance reacts and can
be used to steering on a 100msec timescale, you need to average
a voltage "proxy" signal for upwards of 20 seconds to get the
noise down to level where you don't introduce instability.

The big picture problem is that we are rapidly retiring the rotating
iron, replacing it with switch-mode converters which do not "couple"
the frequency to power balance.

For instance HVDC/AC converters, solar panel farms, and increasingly
wind generators, do not try to drag down the frequency when they
cannot produce more or drag the frequency up when they can produce
more power, they just faithfully track whatever frequency all the
rotating lumps of iron have agreed on.

As more and more rotating iron gets retired, the grid frequency
eventually becomes useless as a "proxy-signal" for grid balance.

Informal and usually undocumented experiments have already shown
that areas of grids which previously were able to run in "island"
mode, are no longer able to do so, due to shortage of rotating iron.

One way we have found to make the voltage a usable fast-reacting
proxy for grid power-balance, is to lock the frequency to GNSS at
1e-5 s level at all major producers, which is trivial for all the
switch-mode kit, and incredibly hard and energy-inefficient for the
rotating iron producers.

The other way is to cut the big grids into smaller grids with HVDC
connections to decouple the frequencies, which allows us to relax
the frequency tolerance for each of these subgrids substantially.

This solution gets even better if you load the HVDC up with capacitance
to act as a short time buffers, but the consequences in terms of
short circuit energy are ... spectacular?

(It is already bad enough with cable capacitance in long HVDC
connections, do the math on 15nF/Km and 100.000 kV yourself.)

All these issues are compounded by the fact that the "50/60Hz or
bust" mentality has been tatooed on the nose of five generations
of HV engineers, to such an extent that many of them are totally
incapable of even imagining anything else, and they all just "know"
that DC is "impossible".

In the long term, HVDC is going to take over, because it beats HVAC
big time on long connections, and it is only a matter of getting
semiconductors into shape before that happens.  That however,
is by no means a trivial task:  It's all about silicon purity.




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Re: [time-nuts] Line Frequency standard change - Possible ?

[Poul-Henning Kamp]

In message <4fbdd81ddf04fc46870db1b9a747269202916...@mbx032-e1-va-8.exch032.ser
verpod.net>, "Thomas D. Erb" writes:

>I was wondering if anyone was familiar with this proposal, is this
>a uncoupling of line frequency from a time standard ?

The interesting thing about this is that all research and experiments
(for instance on the danish island Bornholm) indicates that the only
way we stand any chance of keeping future AC grids under control in the
medium term is to lock the frequency *hard* to UTC.

Its a very interesting topic.

In the traditional AC grid power is produced by big heavy lumps of
rotating iron.  This couples the grid frequency tightly to the
power-balance of the grid:  If the load increases, the generators
magnetic field drags harder slowing the rotor, lowering the frequency
and vice versa.

This makes the grid frequency a "proxy signal" for the power balance,
and very usefully so, because it travels well and noiselessly through
the entire AC grid.

The only other possible "balance signal" is the voltage, and it
suffers from a host of noise mechanisms, from bad contacts and
lightning strikes to temperature, but worst of all, it takes double
hit when you start big induction motors, thus oversignalling the
power deficit.

Where the frequency as "proxy" for grid balance reacts and can
be used to steering on a 100msec timescale, you need to average
a voltage "proxy" signal for upwards of 20 seconds to get the
noise down to level where you don't introduce instability.

The big picture problem is that we are rapidly retiring the rotating
iron, replacing it with switch-mode converters which do not "couple"
the frequency to power balance.

For instance HVDC/AC converters, solar panel farms, and increasingly
wind generators, do not try to drag down the frequency when they
cannot produce more or drag the frequency up when they can produce
more power, they just faithfully track whatever frequency all the
rotating lumps of iron have agreed on.

As more and more rotating iron gets retired, the grid frequency
eventually becomes useless as a "proxy-signal" for grid balance.

Informal and usually undocumented experiments have already shown
that areas of grids which previously were able to run in "island"
mode, are no longer able to do so, due to shortage of rotating iron.

One way we have found to make the voltage a usable fast-reacting
proxy for grid power-balance, is to lock the frequency to GNSS at
1e-5 s level at all major producers, which is trivial for all the
switch-mode kit, and incredibly hard and energy-inefficient for the
rotating iron producers.

The other way is to cut the big grids into smaller grids with HVDC
connections to decouple the frequencies, which allows us to relax
the frequency tolerance for each of these subgrids substantially.

This solution gets even better if you load the HVDC up with capacitance
to act as a short time buffers, but the consequences in terms of
short circuit energy are ... spectacular?

(It is already bad enough with cable capacitance in long HVDC
connections, do the math on 15nF/Km and 100.000 kV yourself.)

All these issues are compounded by the fact that the "50/60Hz or
bust" mentality has been tatooed on the nose of five generations
of HV engineers, to such an extent that many of them are totally
incapable of even imagining anything else, and they all just "know"
that DC is "impossible".

In the long term, HVDC is going to take over, because it beats HVAC
big time on long connections, and it is only a matter of getting
semiconductors into shape before that happens.  That however,
is by no means a trivial task:  It's all about silicon purity.


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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[time-nuts] Line Frequency standard change - Possible ?

[Thomas D. Erb]

I was wondering if anyone was familiar with this proposal, is this a uncoupling 
of line frequency from a time standard ?

The purpose of proposed Reliability Standard PRC-012-2 is to ensure that 
remedial action schemes do not introduce unintentional or  unacceptable 
reliability risks to the bulk electric system.

https://www.ferc.gov/whats-new/comm-meet/2017/011917/E-13.pdf






Thomas D. Erb
t...@electrictime.com /
Electric Time Company, Inc.
Office: 508-359-4396 x 117 / Fax: 508-359-4482
97 West Street Medfield, MA 02052 USA
www.electrictime.com
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