> nor are brief periods of multi-gigawatt draw/dumping as needed.

Actually this is typically an issue for grid batteries.

Spinning generators can easily briefly go to 10x the rated current for a second or so to smooth out big anomalies.

Stationary batteries inverters can't do 10x current spikes ever - the max they can get to is more like 1.2x for a few seconds.

That means you end up needing a lot of batteries to provide the same spinning reserve as one regular power station.

> Completely solved with lithium based grid storage at key locations btw.

That's because Australia has a moderate amount of renewables and prefers to burn fossil fuels. Right now, around 25% of the electricity in Australia is generated by solar or wind.

Spain is past 50% of renewable generation, and their problems are much bigger.

But Australia is tiny: 27M people. Just Spain is twice as big, and the European grid serves 500M people, we don't have the same problems, and probably can't solve them with the Australian solutions.

I think your interpretation is correct. The voltage control is done at the high level of the grid, meaning the control covers bigger generation stations and major substations. Even if it’s small generator, rotating machinery, you won’t have strict voltage control other than its own AVR. The problem I see here is that we embed smaller individual generations at the lower level, where they pump the generated power to the grid at the medium voltage level. When you have majority of your generation at this level, you won’t have strict control over voltage and even frequency, I assume. I’m still digesting the report, but what I am after is whether they really neglected it and if it is not possible to do voltage control with 50% generation coming from renewable and through medium voltage level, aka lower level.

I’m a bit mystified as to how the grid controls voltage at all. The non-renewable plants follow the rules here:

https://www.boe.es/buscar/doc.php?id=BOE-A-2000-5204

7.1(b) seems to be saying that generators connected at 200kV adjust their reactive power generation/absorption in real time according to the voltage they observe, based on a lookup table provided by the grid operator.

This seems sort of sensible according to my limited understanding of the theory of AC grids. You can write some differential equations and pretend everything is continuous (as opposed to being a LUT with 11 steps or so), and you can determine that the grid is stable.

However, check out this shorter report from red eléctrica:

https://d1n1o4zeyfu21r.cloudfront.net/WEB_Incident_%2028A_Sp...

Apparently these 220kV plants are connected to the 400kV grid via transformers in substations that are not owned by the generator operators. And those transformers have “tap changers” that attempt to keep the 220kV secondary side at the correct voltage within some fairly large voltage range on the 400kV side. Won’t this defeat the voltage control that the 220kV generators are supposed to provide? If the grid voltage is high, then absorption of reactive power is needed [0], and the generators are supposed to determine that they need to absorb reactive power (which they can do), but if the tap changer changes its setting, then the generator will not react correctly to the voltage on the 400kV side.

In other words, one would like the generator to absorb reactive power according to P_reactive(primary voltage • 220/400), but the actual behavior is P_reactive(primary voltage • 220/400 • tap changer position), the tap changer position is presumably something like 400/primary voltage, and I don’t understand how the result is supposed to function in any useful way. Adding insult to injury, the red eléctrica repoet authors seem to be suggesting that a bunch of tap changers operators didn’t configure their tap changes well enough to even keep secondary voltages in range.

Does anyone with more familiarity with these systems know how they’re supposed to work?

[0] I can never remember the sign convention for reactive power.

I’ve just read the whole shebang.

While the overall reason for the mass failure you cite is correct - a cascading failure - the interesting bit here are the oscillations that lead to it.

It looks very much like this was driven by algorithmic volatility trading of electricity spots - overproduction, price goes negative, buys placed, production ramps in response to rising price, price rises, sells placed, production falls due to falling price. The period of the oscillations in the grid seen before the blackout suggest a relatively slow cycle, and what they describe in the report sounds very much like this was an interaction between price-driven supply and real world supply.

It does speak to there being inadequate storage available on the grid to smooth demand and therefore pricing, but it also suggests that in certain conditions a harmonic can be set up between the market and price-driven production with catastrophic consequences.

Check this shorter report by the operator:

https://d1n1o4zeyfu21r.cloudfront.net/WEB_Incident_%2028A_Sp...

>I feel this could have been left out.

It's pretty much their one and only chance to warn the authorities that there's a risk, so if they choose to ignore it, well, nobody can claim they weren't informed.

Don't worry, some news outlets will summarize this as "renewables = bad" regardless of what the report actually says.

Oh wait, they already did: https://www.telegraph.co.uk/business/2025/06/18/renewable-en...

Ed: Do I need a /s tag here or something? My point was that we shouldn't worry too much about about the presentation of the report, its actual contents will be spun to suit any narrative regardless.

There's been a shit-ton of misinformation about cyberattacks within the first hour of the outage, and the public were unfortunately very receptive to it, so I guess they're trying to preempt those concerns?

I suppose other system operators might have better a state estimator and wide area monitoring system. But real-time system operation is universally an engineer sitting behind a desk, looking at their screen, and trying to make the best decision with whatever data they have.

The actions that were taken did not strike me as out of the ordinary.

Sort of:

For the oscillations, the European grid in general is large enough that the time it takes for the energy to flow (at some fraction of the speed of light!) from one side of it to the other is not negligible: it's not a case of delays at the power plant, but delays in the network itself which can cause the various natural and artificial feedback loops in the circuit to start to become unstable and oscillate. In this specific incident, there's some implication in the report that the largest oscillation was unusual and may have been generated by single plant essentially oscillating on its own, for reasons unknown.

In either case, the oscillations were not the direct cause of the blackout: they were controlled, but the steps to control them put the system into a more fragile state. This is because of reactive power. The voltage in the system is due to both the 'real power', i.e. the power generated by the plants and consumed by consumers in the grid each cycle of the 50Hz AC, but also 'reactive power', which is energy that is absorbed by the consumers and the grid itself (all the power lines and transformers) and then bounced back to the generators each cycle. This is the basic 'inductor-capacitor' oscillation. This reactive power is considered to be 'generated' by capacitance and 'consumed' by inductance, though this distinction is arbitrary.

So, after the grid operator had stopped the oscillations, the grid was 'generating' a lot more reactive power, because damping down the oscillations generally involves connecting more things together so they don't fight each other as much. It also _lowered_ the grid voltage on average, so various bits of equipment were essentially adjusting their transformer ratio with the high-voltage interconnect to try to adjust for it.

Apart from these measures, the generators on the grid are generally supposed to contribute towards the voltage regulation, which helps with both damping these effects and reducing the change of the runaway spike that happened. But crucially, there's a difference between what they (by regulation, not necessarily technical capacity!) do. The traditional generators have active voltage control, which means they actively adjust how much reactive power they generate or absorb depending on the voltage on the lines. Renewable generators, by contrast, have a fixed ratio: they will be set to generate or absorb reactive power at a certain percentage of the real power (a few percent usually), they don't actively adjust this (they're not allowed to under the rules of the grid).

So, after the oscillation, the grid is generating a lot of reactive power and the power plants are absorbing it, but there's a lot of renewables around, which can't actively control voltage, they're just passively contributing a certain amount. Then there's a fairly rapid drop in real power output, which seems to be related to the energy market as some plants decide to curtail. This is expected, but renewables can do it pretty quickly compared to conventional plants. This means that the amount of reactive power being absorbed drops, i.e., counterintuitively a plant producing less power means the voltage rises.

In theory, there should be enough voltage control from conventional sources to deal with this, but in general they prove to not absorb as much reactive power as they were expected to, and the report calls out one plant which seems to just not be doing any control at all, it's more or less just doing something random. This means the voltage keeps rising, and, perhaps in part due to the adjustments in the transformer ratios, this means another plant trips off, at a lower voltage than it should (this is, basically, for protection: the equipment can only take so much voltage before it's damaged, but there's rules about what level of voltage it should withstand and, in extreme cases, for how long). This then makes the voltage rise more, and it's a fairly rapid cascade of failure from there, and many plants kick offline in a matter of seconds, and only then does the frequency of the grid start to drop significantly, but it's already too late because there's too much demand for the supply.

The recommendations of the report basically boil down to:

- Figure out why the plants (renewable and conventional) didn't have the capabilities the grid operator thought they did (or why they were actively causing problems), and fix them.

- Fix the regulations so renewable plants are allowed to contribute to active voltage control, and incentivize them to do so.

- Adjust the market rules so that plants have to give more notice before increasing or decreasing supply in response to prices

- Improve the monitoring of the grid and add other tools to help with voltage control (including better interconnects with the rest of Europe)

Based on the redacted bits, it is mostly company names and locations.

The engineers knew exactly what’s going to happen, the report is politically redacted. Very unfortunate, but completely expected.

> In the systems with network traffic evaluation probes, no records consistent with unauthorized activity have been observed, such as lateral movements, network traces or file movements for vulnerability exploitation or privilege escalation, among others.

> However, as is common in networks and information systems in any sector, other risks have been identified, such as vulnerabilities, deficiencies or inadequate configurations of security measures, which may expose networks and systems to potential risks, for which a series of measures are proposed.

Infrastructure in general has pretty terrible security practices, so I won't bemoan someone finding a useful soapbox to remind them to shape up a bit, even if it isn't the core cause of this particular issue (and it's probably also a reaction to various rumours/speculation about a cyberattack).

> but the fans of renewables just flagged it

As moderators we can only guess why people flag things, but there are other reasons why people may have flagged that comment, the foremost being that it broke the guidelines due to its inflammatory style.

On Hacker News we want to be able to discuss difficult topics involving arguments people may find counter to their assumptions, but you need to express things in a way that's persuasive rather than combative.

https://news.ycombinator.com/newsguidelines.html

What I'm reading from that quote is that the issue wasn't renewables as such, but an issue of power generation reacting too quickly and too intensely to price fluctuations. "Renewables" only matter insofar as they're the sort of generation that, under the current regulatory regime, get to react to those pricing changes.

But the quote literally spells out it was market forces, not some instability in solar generation?

Your other comment probably got flagged because it started with a huge straw man and had multiple unwarranted jabs in it.

Should’ve said ‘not enough spinning mass’ and it’d be perfectly fine for the politically correct and mean the same thing. This was highlighted as a risk for years and it finally materialized.

People are having three different conversations at the same time:

– the concrete causes of this specific blackout; – how the existing grid is not prepared to deal with the current energy mix; – the energy policy of the past decades, from the nuclear moratorium in the 80s to the large subsidies for renewable generation of the past couple decades.

A person's strong opinion on any one of these issues will inevitably influence their opinion on the others.

It's worth pointing out that the worst part of the behaviour of renewables specifically in this incident (a fixed power factor for managing reactive power), is currently mandated by the regulations in Spain, even though many of them are already equipped to do voltage control.

You quoted

>the most plausible explanation is that it is due to market reasons (prices)

Seems to be market conditions or manipulations or inefficiencies in the market.