Spain and Portugal blackout blamed on solar power dependency | Hacker News Reader

Spain and Portugal blackout blamed on solar power dependency

ft.com

6 pointsmartinald10 comments

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Headline incorrect. Shame on the FT fossils.

- They had too much power being generated ( largely solar ).

- Their system handles too much power by turning off fossil fuel generators.

- There weren't enough of those connected to reduce the power enough.

- The system broke down.

So it is INCORRECT to blame "solar power dependency". What is to blame is a system that cannot handle too much power properly.

This isn't quite correct. It is more like this

- They had too much power being generated ( largely solar ).

- Their system handles too much power by turning off fossil fuel generators.

- Cloud coverage/HV line failure/something else happens, causing a drop in output from those solar plants

- Because you have turned off the fossil fuel generators, you cannot compensate for this quickly enough. There is not enough inertia in the system and no ability to ramp up power to compensate quickly enough

So it's not a system that cannot handle too much power, it is a fragile system that struggles when there is 'too much power' to recover from outages of that.

What should have happened solar was disconnected by the grid before CCGT when there is 'too much power'. Instead they ramped down CCGT and kept the solar, leading to a very fragile state.

This can't possibly be true! I'm only familiar with the North American power grid, but there would be "spinning reserve" to ensure events such as this wouldn't happen. When you bid variable power sources such as wind and solar into the market, you have to back it up with readily available, secure generation to match the load forecast. The load forecast and generation forecast is done for every 15-minute interval of the day, or 5-minute interval - depending on the control area. These forecasts are done weekly, daily, and hourly.

If you have coal fired generation units, then those would typically be used for your spinning reserve since you can't (shouldn't) spin down those units since that dramatically decreases their operational lifetime. Otherwise, use your fast fire "peaker" units to guarantee the power.

If what you're saying is true, then they don't have secure grid management in place which is shocking because North America has had these policies and practices in place for decades.

No this is seemingly what happened, and yes I agree (I'm in the UK). The UK national grid has 2.5-3GW of CCGT gas always running for this reason. Spain had less than 1GW before the outage, I suspect it was lower but the snapshot data wasn't granular enough.

Spain was saying they were running on 100% renewables just a few days ago, which means zero CCGT if you take that at face value.

Furthermore I read they had 60% of their large hydro plants offline for maintenance at the time of the outage, further reducing inertia.

I was also absolutely shocked when I saw the grid dashboard and saw it was ~500MW of CCGT against 15GW+ of Solar PV.

In "fairness" this is possible though still. I suspect that there was a sub 5/15 min drop in solar output because of cloud coverage, which arguably isn't taken account in forecasting.

Even if all this were true, the problem isn't renewables per se, but rather poor grid management. I'm flabbergasted to learn their grid management is so poor. As I said, here in the States, variable power sources must be backed by confirmed power sources that are ready to ramp-up. Here in North America, we use Automated Generation Control (AGC) to control the unit to maintain the phase angle at zero. If the solar output dropped, then the confirmed units would have automatically ramped-up and maintained the proper phase angle.

After minimal research, I found that Spain, and most of Europe, also uses AGC. The system should have "just worked" and prevented this sort of problem. It may be several days before they identify a root cause.

This supports my version:

"Sanz said: “There was an imbalance of supply. [The grid operator] needed to reduce electricity supply, but when it resorts to firm facilities to reduce load, it can barely do so because they were barely connected.”

"There is not enough inertia in the system and no ability to ramp up power to compensate quickly enough

So it's not a system that cannot handle too much power, it is a fragile system that struggles when there is 'too much power' to recover from outages of that." Didn't you just confirm that it actually was the system?

Still no official reason declared, just speculation, hence the distancing in the headline.

Do we trust the official reason given the Spanish PM has effectively ruled out renewables? I'm not being facetious as there was a near miss in the UK in winter with very low renewable output and the newly nationalised NESO grid operator was widely condemned for downplaying the severity of it in the repot.

This basically tracks with exactly what I suspected had happened given it occured at the peak of solar output and they were running so little flexible generation resources.

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