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 +0000, 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 > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. >

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 <magnus@rubidium.dyndns.org> 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 >>> <4FBDD81DDF04FC46870DB1B9A747269202916B42@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. >>> >>> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.

-------- In message <9FD9BECA-832A-4C38-9799-4A31625F7C82@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 phk@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.

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 <magnus@rubidium.dyndns.org> 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 >>>> <4FBDD81DDF04FC46870DB1B9A747269202916B42@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. >>>> >>>> >>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. >

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" <davidwhess@gmail.com> 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. > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/m > ailman/listinfo/time-nuts > and follow the instructions there. >

-------- In message <006a1c6a-0b2f-16fd-5fef-64352ff14488@earthlink.net>, jimlux writes: >On 2/9/17 4:03 PM, Poul-Henning Kamp wrote: >> -------- >> In message <63beea7a-f9fc-6e1d-b855-2c7056de3cc7@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 phk@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.

-------- In message <344e0d5f-e79f-fcfa-eba5-4cf50e0476cb@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 phk@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.