So all I have to do is supply a cheap voltage outputter and I can fool the inverters into working when grid goes downIt has nothing to do with loads.
It's the loss of voltage.
So all I have to do is supply a cheap voltage outputter and I can fool the inverters into working when grid goes downIt has nothing to do with loads.
It's the loss of voltage.
It’s good learning for the methods it presents, but it does not claim to be presenting all or even the best methods that exist.Here's an article presenting various anti islanding methods.
Yes, until the grid-tied inverter pushes current to that source. When that happens and if the source cannot take it, the really bad day begins.So all I have to do is supply a cheap voltage outputter and I can fool the inverters into working when grid goes down
Microinverters or hybrid inverters cannot detect a grid open circuit by voltage. The grid is 'immovable' in terms of trying to pull the phase. The microinverters are not and they follow the master (grid). They require near continuous phase tracking correction from the master grid AC zero crossings.I am interested to know the answer as well. And if your neighborhood is highly solarized why wouldn't 50 or 100 microinverters tend to go into island mode?
I suspect it has something to do with a necessary higher voltage for export.
It is the utility power alternators rpm's that determines the grid frequency.I think many here don’t understand what this means or misunderstand it. I will try to explain further what you are saying, hopefully I don’t muddy it more:
1) the “grid” is huge. If you want to speed the grid up (increase the frequency) you must supply enough power to the grid to measurably increase the speed of every single motor on the grid. Not just your neighbors, but everyone in your county, state and neighboring states. In the US there are several large regions that form their own “grid” I forget exactly how many.
Yes, in fact, if you have a specific model of inverter... hard to say which control algorithm it's going to use... not much open source in this sector lolIt’s good learning for the methods it presents, but it does not claim to be presenting all or even the best methods that exist.
And thanks for pointing to the study, not complaining- just pointing out it’s a very complex subject and any single source will not give a complete picture.
within minutes of a total shutdown? scaryMicroinverters or hybrid inverters cannot detect a grid open circuit by voltage. The grid is 'immovable' in terms of trying to pull the phase. The microinverters are not and they follow the master (grid). They require near continuous phase tracking correction from the master grid AC zero crossings.
Number of motor's on the grid has nothing to do with frequency.
It is the utility power alternators rpm's that determines the grid frequency.
Utilities have to predict the network load versus time of day in advance to 'stoke the coals' enough to have enough generators online with enough steam (literally) to produce the demanded power. When they make the call wrong, and only prepare for lower demand, all alternators get overloaded and slow down a small amount. When they get the call wrong with too much generation capability, all the power generation alternators speed up in rpm's, increasing the grid frequency a bit. Utilities within the same color grid can share power making it easier for power demands to average out.
Nuclear power plants are slowest to react to changes in power demand. Natural gas turbo-shaft jet engine power plants are the quickest to react to changes in power demand. They are sometimes called 'turbine peakers'. (good name for a stiff drink)
There are three major independent phased grids in the continental U.S.. All power stations within the same-colored areas are in phase synchronization. In the eastern grid, your little PV system would have to overwhelm and shift the frequency of every utility power plant from Florida to North Dakota.
View attachment 197024
The yellow 'don't mess with Texas' grid is independent and not phase synchronized to other major grids so they cannot share power from their neighbor states' grids. This got them in big trouble during the Feb 2021 ice storm/freeze. The graph below is what happened to their grid frequency as their alternators got overloaded from all the electric heating turned on when it got cold. They were within a couple of minutes of a total grid 'black' shutdown and had to drop large sections of service areas to avoid a catastrophic 'black' system shutdown. Restarting a grid from a total 'black' shutdown can take days to accomplish and needs to be avoided at all cost.
View attachment 197025
OK, so this phase shift is constantly tested against the grid and whereas the grid is fixed and won't budge other inverters would themselves 'follow' the shift attempt and allow the shift to change.Yes it does. It periodically pushes a phase wiggle against grid to test that grid is still present.
Yes, they generally try to raise frequency.I am guessing then, that:-
a) all inverters attempt to shift in one direction (e.g. faster) so they don't fight against each other.
b) the measured cut out time for my Solis is around 220ms to 380ms depending on load, according to the test sheet, so at 50Hz, that is a disconnection within just 11 cycles of main, and that includes the relay release time - so that's some going! Guess these inverters must be trying to push the frequency on every single cycle then to observe and react that quickly.
I concur with everything you state except “The number of motors on grid have nothing to do with frequency “. Of course they don’t and that’s not what I said. The number of motors (and everything thing else who’s load draw is effected by frequency) and also the number of generators absolutely impacts how much power it takes to increase grid frequency. For a single generation device to increase grid frequency it would have to be able produce enough power to pick up substantial load from other generators as well as the additional load that would be present (at least momentarily) by motors and other devices.Number of motor's on the grid has nothing to do with frequency.
It is the utility power alternators rpm's that determines the grid frequency.
I would like to add an asterisk here that the Texas interconnection has no synchronous power sharing but there are a handful of asynchronous ties. 2 DC to Eastern and 1 VFT to Mexico. They're not huge, but they exist.The yellow 'don't mess with Texas' grid is independent and not phase synchronized to other major grids so they cannot share power from their neighbor states' grids.
Don't worry it was clear to me as a reader he had misread your intended meaning.I concur with everything you state except “The number of motors on grid have nothing to do with frequency “. Of course they don’t and that’s not what I said.
dc as in direct current??I would like to add an asterisk here that the Texas interconnection has no synchronous power sharing but there are a handful of asynchronous ties. 2 DC to Eastern and 1 VFT to Mexico. They're not huge, but they exist.
Yes. We use it inside the grids too. But it's especially applicable for ties between separate grids.dc as in direct current??
Wow. I had no idea that DC could be transported at high voltages. My mind is blown right now.Yes. We use it inside the grids too. But it's especially applicable for ties between separate grids.
Pacific DC Intertie - Wikipedia
en.wikipedia.org
So the next question is 'how'? what component is actually doing this - presumably a MOSFET or IGBT?
That seems beg the question, how much wiggling can the grid take as more and more residential solar wigglers are added? Do solar farms wiggle?The point was, the reason your “wiggle “ works is an inverter can’t effect grid frequency.
Unfortunately, the vast majority of utility sized turbine generators wiggle badly, especially in the older coal plants, but even new machines in modern combined cycle plants present continuous struggles with the tendency for all mechanical devices such as valves and actuators to stick. No inverter can wiggle as much as a utility sized steam turbine.That seems beg the question, how much wiggling can the grid take as more and more residential solar wigglers are added? Do solar farms wiggle?
Us non-wigglers want to know.