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How the electricity markets respond to a nuclear trip

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Re: How the electricity markets respond to a nuclear trip

#21

Post by adrianmonk »

rtkwe wrote: post #9
kccqzy wrote: post #4

Earlier quoted context omitted.

Most curtailment IIRC is due to insufficient transmission capacity. I doubt curtailed solar can be called upon in an emergency unless the emergency is located very close to the curtailed solar.

The transmission lines run to solar farms should be able to take 100% of the output of the farm and then some otherwise the farm was over built and wasted money.

At short distances from the solar farm, yes. But it's not 100% in every direction for arbitrarily long distance. At some point, you assume the energy will be tend to be used sort of near where it's generated.

To put it another way, if you build solar between city A and city B, would you build it so it can still be fully utilized even if city A stops using any power and city B wants all of it? No, you assume city A is always going to need some power.

Re: How the electricity markets respond to a nuclear trip

#22

Post by callalex »

rtkwe wrote: post #9
kccqzy wrote: post #4

Earlier quoted context omitted.

Most curtailment IIRC is due to insufficient transmission capacity. I doubt curtailed solar can be called upon in an emergency unless the emergency is located very close to the curtailed solar.

The transmission lines run to solar farms should be able to take 100% of the output of the farm and then some otherwise the farm was over built and wasted money.

By this definition all reserve capacity is wasted money. That is clearly false, as demonstrated by the event in this article _not_ leading to failure and harm.

Re: How the electricity markets respond to a nuclear trip

#23

Post by Reason077 »

toomuchtodo wrote: post #2

Something interesting is that with substantial solar and batteries being deployed in the ERCOT market (in scope grid operator for this piece), solar generation in excess of what the grid can consume with load combined with grid forming inverters (vs traditional grid following) can step in when called upon if a traditionally firmer generator (coal or nuclear) trips out. The potential is already there (photons hitting…

> "(I am not familiar how long it takes from ISO signal to inverter command)."

The grid frequency itself functions as a signal: a deviation below 50/60 Hz indicates support is needed, and a deviation above means curtailment is needed (or load added).

Instant frequency-response assets such as batteries typically monitor the frequency independently and respond as required. They don't need to wait for explicit signals from the ISO.

Re: How the electricity markets respond to a nuclear trip

#24

Post by thijson »

gunapologist99 wrote: post #17
Symbiote wrote: post #3

Where does the 1500MW of heat the reactor is producing go, immediately after the generators are isolated from the grid?

It seems like you might really be asking about a meltdown scenario. The reaction can be slowed with control rods, which stops/minimizes the heat from being generated. The previously generated heat still needs to be handled, however (by evaporation). https://en.wikipedia.org/wiki/Nuclear_reactor A meltdown occurs when the reaction can't be slowed down through normal means because the safety systems fail. For example,…

The control rods don't stop decay heat from being produced. That's what happened with Fukushima.

Also, nuclear poisons (neutron absorbers) build up after the reactor is shut down. After the control rods are withdrawn it takes a few days for the poisons to be burned up and the reactor can resume power production. I think they call that poisoning out the reactor.

https://en.wikipedia.org/wiki/Neutron_poison

Re: How the electricity markets respond to a nuclear trip

#25

Post by bell-cot »

huijzer wrote: post #11
toomuchtodo wrote: post #2

Something interesting is that with substantial solar and batteries being deployed in the ERCOT market (in scope grid operator for this piece), solar generation in excess of what the grid can consume with load combined with grid forming inverters (vs traditional grid following) can step in when called upon if a traditionally firmer generator (coal or nuclear) trips out. The potential is already there (photons hitting…

An individual inverter can usually switch in about 4 ms. A Tesla Megapack can go from 0% output to max output in 100 ms. Conversely, gas turbines (the fastest type of traditional power plant) takes about a minute to go from say 40% to 60%. Even in the fastest possible design, there is a mechanical rotor (kinetic energy) that has to change speed. What I mean to say is that solar and batteries are likely an order of ma…

IANAEE (not an electrical engineer), but doesn't a gas turbine spin at a constant speed to drive a 60Hz generator, regardless of whether it's running at 20%, 60%, or 100% of capacity?

Re: How the electricity markets respond to a nuclear trip

#26

Post by thijson »

thijson wrote: post #24
gunapologist99 wrote: post #17

Earlier quoted context omitted.

It seems like you might really be asking about a meltdown scenario. The reaction can be slowed with control rods, which stops/minimizes the heat from being generated. The previously generated heat still needs to be handled, however (by evaporation). https://en.wikipedia.org/wiki/Nuclear_reactor A meltdown occurs when the reaction can't be slowed down through normal means because the safety systems fail. For example,…

The control rods don't stop decay heat from being produced. That's what happened with Fukushima. Also, nuclear poisons (neutron absorbers) build up after the reactor is shut down. After the control rods are withdrawn it takes a few days for the poisons to be burned up and the reactor can resume power production. I think they call that poisoning out the reactor. https://en.wikipedia.org/wiki/Neutron_poison

When the Northeast power grid went down down in 2003, the Bruce Nuclear Power Development was almost entirely kicked off the grid. It was able to keep ticking over at a few percent of power output though because of a feeder line that went North. This prevented the reactors from poisoning out, and allowed them to come back faster than if they had poisoned out.

Re: How the electricity markets respond to a nuclear trip

#27

Post by bell-cot »

Symbiote wrote: post #3

Where does the 1500MW of heat the reactor is producing go, immediately after the generators are isolated from the grid?

In general, any sort of "boil water to steam, use steam to drive turbines" system can vent the hot steam from the boilers to the atmosphere. There's a big reserve tank of cold boiler feed water, to replace the water you're no longer getting back from the steam condensers (attached to the "OUT" steam pipe on the turbine). So the boilers will keep soaking up just as much heat, while the engineers scramble to reduce the heat coming in from the burning wood, or burning coal, or burning oil, or fissioning atoms, or whatever.

Re: How the electricity markets respond to a nuclear trip

#28

Post by rtkwe »

callalex wrote: post #22
rtkwe wrote: post #9

Earlier quoted context omitted.

The transmission lines run to solar farms should be able to take 100% of the output of the farm and then some otherwise the farm was over built and wasted money.

By this definition all reserve capacity is wasted money. That is clearly false, as demonstrated by the event in this article _not_ leading to failure and harm.

I'm not talking about reserve capacity at the grid level. I'm talking about excess capacity at the individual generation plant level that exceeds the grids capacity to take in. If you can't output the energy onto the grid the only benefit is for local maintenance and you don't need huge amounts of excess capacity to solve that and that excess doesn't help in the event of a large base producer like a nuclear plant going offline because it can't get onto the grid!

Re: How the electricity markets respond to a nuclear trip

#29

Post by markus92 »

bell-cot wrote: post #25
huijzer wrote: post #11

Earlier quoted context omitted.

An individual inverter can usually switch in about 4 ms. A Tesla Megapack can go from 0% output to max output in 100 ms. Conversely, gas turbines (the fastest type of traditional power plant) takes about a minute to go from say 40% to 60%. Even in the fastest possible design, there is a mechanical rotor (kinetic energy) that has to change speed. What I mean to say is that solar and batteries are likely an order of ma…

IANAEE (not an electrical engineer), but doesn't a gas turbine spin at a constant speed to drive a 60Hz generator, regardless of whether it's running at 20%, 60%, or 100% of capacity?

When there’s a load imbalance on the grid (more load than capacity), the turbines physically slow down as inertial energy is extracted from them. This causes the grid frequency to drop. It takes some time to ramp up production and speed up the turbine etc.

Re: How the electricity markets respond to a nuclear trip

#30

Post by toomuchtodo »

Reason077 wrote: post #23
toomuchtodo wrote: post #2

Something interesting is that with substantial solar and batteries being deployed in the ERCOT market (in scope grid operator for this piece), solar generation in excess of what the grid can consume with load combined with grid forming inverters (vs traditional grid following) can step in when called upon if a traditionally firmer generator (coal or nuclear) trips out. The potential is already there (photons hitting…

> "(I am not familiar how long it takes from ISO signal to inverter command)." The grid frequency itself functions as a signal: a deviation below 50/60 Hz indicates support is needed, and a deviation above means curtailment is needed (or load added). Instant frequency-response assets such as batteries typically monitor the frequency independently and respond as required. They don't need to wait for explicit signals f…

True! But this signal is typically locally monitored and responded to by individual assets ("frequency response" ancillary services). That is distinct from a grid operator, ISO, whomever is orchestrating grid health to call on generating units due to a supply crunch. Tesla Megapacks can respond within milliseconds to frequency and voltage sags (when configured to provide these services), but Autobidder is what orchestrates and pushes out overarching power control strategy to individual assets (for example) [1] [2] [3].

[1] https://www.tesla.com/support/energy/tesla-software/autobidd...

[2] https://www.tesla.com/support/energy/tesla-software

[3] https://electrek.co/2023/09/15/tesla-autobidder-product-330-...

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