Induced atmospheric oscillations.

We don't know.

As others have pointed out, it is perfectly possible to develop nonconventional solutions, to provide synthetic inertia, or whatever the correct term is.

I was listening to a youtube thing on bunker buster bombs and their limitations when faced with defences against them. It made the point politicians don't really care about the truth, they just hear what they want to hear, "ideals", and don't hear "caveats".

What a dreadful thing to say!

As the push for renewables continues, and the grid becomes less stable, it’s the fault of conventional power plants?

That’s the thinking of the loony bin, unfortunately so characteristic of the renewables lobby.

I think we can all see where that’s headed…

It is *not a question of controlling the output voltage*. The grid itself has effectively only one output voltage and frequency. The generators must be able to call on power reserves to maintain that.

Renewable sources *HAVE NO POWER RESERVES*. It's that simple. So if the load goes up the frequency and voltage drops FAST. There is no energy reserve of spinning turbines to maintain it, and if the frequency goes too low most powerstations will disconnect themselves to prevent damage. Adding batteries is supposed to prevent that. The batteries have power reserves. But batteries cost money and we have gas power stations so why waste money on them ?

And the answer is because greedy renewable operators want to see as much renewable energy on the grid as possible they force the gas power stations off it.

And the more renewables energy there is the greater the risk. Low load and lots of sun...bad news.

Imagine one lorry being pushed along by 500 people. They all have to maintain its speed up hill and downhill. If one person drops off it immediately slows down. Increasing the load on the others. If they cant push harder they drop off as well.

Yes. It costs them more gas, more wear and tear, and far far less income to do it. So they have to charge more.

We do.

Its called batteries. But batteries cost money. They don't earn money.

Twas ever thus.

The good news is that my wife speaks fluent Spanish. The bad news is she wouldn't know a reactive load if it bit her, and she doesn't want to know either, so there's no point in showing it to her.

I know enough to know the title begins "The non-confidential version..."

But I read the English one, which is much shorter too.

They mention the frequency oscillations, which reached 0.6Hz, and state that it is linked to voltage oscillations.

"During the incident analysis, it was determined that the oscillation was not natural to the system but rather forced. This oscillation is observed with significant amplitude at a Photovoltaic Plant located in province of Badajoz (PV Plant A). At the time of the oscillations, the plant was generating approximately 250 MW. Since the oscillation was forced, it ceased once the plant stabilizes it."

was an interesting paragraph. And while it's quite clear I don't understand this high power AC electrical stuff that seems to be the original trigger.

They've got stuff on there to manage the power factor in their grid - and it wasn't coping. The frequency began to drop, plants tripped all over the place, load shedding was going on - and the voltage kept going _up_!

Andy

It sounds like a desperate attempt to exonerate renewables. And 'reactive power' is bullshit.

Always been lots of it about without crashing a grid

Until renewables

Yes. My point was that this particular incident was not caused by insufficient reserve of energy. Nothing was being overloaded, the system was *underloaded* and was producing an excess of electricity:

"Electricity demand on the morning of April 28 was relatively low, which contributed to the repeated overvoltage on the country’s transmission network.

Total demand on Spain’s peninsula network prior to the blackout was just 25,184 megawatts, well below the historical maximum of 44,876 megawatts.

Weather (temperatures were mild), time of day (noon) and day of the week (Monday) all contributed to relatively low demand.

But low demand can threaten grid stability because it can cause voltage to drift above the safe operating limits set by the system."

The latter is understandable with rotating thermal generators, and those in charge would have acted to shed generating capacity, not load. It is not understandable with the synthesised AC produced by renewable generators. Windmills can have the alternator excitation current reduced or the blade pitch reduced, solar cells can simply be regulated, and no harm will come to them if their full outputs are not utilised. The grid voltage should *not* have risen uncontrollably with a low load.

That merely means they shot off all gas and thermal capacity.

I don't think it actually can do that.The response to underload is not overvolatge, it is over frequency.

I dont believe it did. I believe that the renewable generators simply lost a master clock to synch to and went 'off reservation'

Renewable output is sun an wind dependent and would be constantly fluctuating.

The conventional generation would have seen an effective load (real load minus renewable load) going up and down faster than they could absorb. They would then probably trip.

In the end it doesn't make much difference whether the instantaneous mismatch between real load and renewable output was positive or negative, it was just too much for the spinning mass on grid to absorb and smooth out.

With a spinning rust generator that's certainly the case.

I'm not at all sure the link is still there with these non-spinning generators. They also don't have a built-in capacity to deal with reactive loads, and there is mention of a lot of reactive stuff in the document.

Andy

Indeed. A red herring, mostly

Of course a wind turbine can deal with reactive loads.

On generators on the grid, one direction of correction is harder to do than the other. There are leading and lagging VARs. And one direction has a much smaller allowed adjustment range. The equipment will overheat if pushed too far.

By billing large consumers or producers of reactive power, the power company hopes that the customer will correct their power factor, so the grid doesn't have to do all the work. At some industrial facilities, they install capacitor banks.

Originally, LED lightbulbs were being power factor corrected, but now, it's just same old same old, just as bad as CFLs in terms of implementation. The cheap lightbulb, brings with it, no power factor correction.

There is a report on the Spanish outage now.

The Iberian blackout was a consequence of grid management, not any power source.

Renewable power... had nothing to do with its recent blackout.

Part of the problem then, was plants (facilities) that did not respond in the correct direction or way, when called on to correct. Making matters worse.

Paul

OK, we have an old fashioned generator. It doesn't matter where it gets its steam from, it spins at a rate directly and completely linked to the grid frequency. Turn down the steam, and it will try to slow down. Until it starts being pushed around by the rest of the grid. Turn up the steam, and it will push a bit harder. But it won't go faster or slower.

Over the hill from me there's a wind farm. They point in all sorts of directions at the same time, and more often than not one or two of them are parked. Even when it's windy.

But watch them for a while, and you'll notice that their speed varies, and they aren't even synchronised with each other. It's obvious to me that whatever is on the top of that tower is not locked to a constant speed by the grid the way a steam generator is.

I had assumed that the generators in each tower were linked to some sort of fancy electronic wotsit that would take the power they generator, and feed it out to the grid at the right frequency. Just the way a solar farm does, when its panels generate DC.

Am I wrong? How do wind farms do it?

Andy

Thank you, an interesting (and short :) ) read.

I wouldn't whitewash renewables as much as you do. With old fashioned synchronous spinning generators a lot of that stability is built into the design.

In the new world it's got to be looked after - and it looks as though it wasn't.

The report has been released.

The Iberian blackout was a consequence of grid management, not any power source.

Renewable power... had nothing to do with its recent blackout.

Apparently, some units, when called on to produce whatever leading or lagging VARS that were required, pulled in the wrong direction. And I think that's the part they will be working on next, you know, rogue engineer tied in chair, rubber hoses applied and so on.

I've watched the low level linesmen work on our substation, and you really have to wonder...

There was a local news article the other day here, describing how much the grid has to be expanded by. And, how much money the power company has for doing it, and what rate they can install new equipment. Very amusing. The summary of the story says my bill will go up by $6, because they wrote that news story. That's all I need to know, as a bill payer. The $6 won't pay for the changes, but it will buy coffees for the staff.

Paul

That's just a different website, referring to the same report that Nick Finnigan mentioned 10 days ago, isn't it?

Also, the final part of the Heathrow substation report is due by Monday ...

The report was produced in a timely manner.

If done here, ours would take at least that long to do. Because there could be liability issues or court cases, you have to do the job right. The workmanship of the report could be called into question, in a court.

Paul

What they do is have a nice inverter. First of all they convert all the AC from the turbines into DC.

Then they feed that into a circuit that chops it between +- whatever voltage is on the grid. Very fast. There may be an upconverter first to match voltages

Then they vary the width of the pulses so that when the grid is max positive, they are positive for the longest time. and vice versa for negative. Pulse width modulation.

Running that through an LC circuit turns it into a respectable 50Hz sine wave. Whose amplitude phase and frequency is under software control.

That is coupled into the grid.

Then the phase of that sine wave is advanced ever so slightly lead the grid so as to feed power into the grid.

If the inverter tries to draw too much, the input from the turbine will drop and the turbine will stop there. It simply *cannot* deliver more power.

However there will be enough capacitor smoothing in the DC to allow it to deliver a bit more reactive power than average 'ohmic' power.

The problem is that if the load goes up, all these turbines will back off the phase angle to avoid getting overloaded, and the load on any

Once the grid starts to go unstable, everything will ultimately disconnect.

A battery in each turbine capable of say 10% power increase over average wind power with an inverter designed to handle short term overdemand, would stabilise things - and that is why batteries a being added. Not to make solar power work in winter, nut to stop it collapsing in summer.

No, power can get into the grid from simply powering current in phase with the voltage.

Lagging or leading has the effect of providing a reactance that is equivalent to a leading or lagging load.

Reactive power is a simple way of describing the (out of phase) phase relationship between volts and amps, where reactive power serves no purpose in power transmission and creates losses.

That would be no more stress than when generating power? DO you understand what you're saying? Feel free to provide more details. You never know I could be wrong.

Yes, energy storage systems are in place in many jurisdictions to smooth out disturbances in load. They don't have to be at the windmill, or the solar panel.