Today the research focuses on "Grid forming inverters". Taking the same principle as powering a home in island mode and stretching it to the entire grid allowing non-synchronous generators to provide the system strength.
Over time they are a net power drain for the grid, but as parent says offer synthetic grid stability independent of power sources.
(Sorry for asking such a poorly stated question that I really haven't thought through — I know very little about electricity and you seem to understand quite a lot about this subject.)
Someone have a link to 101 power transmission? I find this fascinating.
The phase difference is not really about distance it's more about energy flows, where it's lagging there more power is used and where it is leading more power is generated. The flow will be from early phase to later.
But how would current and voltage be stabilized in that case? Just huge capacitors? Chemical batteries?
Grid itself can't store energy, the generation and consumption needs to be in balance.
If transmission balance goes out of whack more electrons want to flow to specific places and will always try to take the path of least resistance.
Those paths (as in transmission lines) have their current capacity measured in Amps and when it gets too much their protective equipment in the for of active or passive circuit breakers will take them offline (trip) therefore moving the current down next best paths and further increasing the likelihood of trips.
Voltage is regulated by changing the windings of transformers in AC-AC systems or by transistors/thyristors in DC coupled networks.
Frequency has usually been regulated by spinning mass, a steam powered generator has a pretty large inertia and when it slows down there is a governor or other control mechanism to add energy to the generator via opening steam valves and maybe adding fuel. If speed goes too high it is also reduced.
For large load changes there are further compensatory mechanisms. Like heavy industrial plants measure grid frequency and when it falls below lets say 49.9Hz then they will immediately trip themselves offline and shed a huge amount of load from the grid. They get paid for this.
So while there may be huge variance in on both sides (a sunny day, a wind gust versus switching on the AC a train leaving the station) the only way to adjust is open a valve add steam, fuel? Will that scale to when, say, 80% of electricity sources are weather dependent? Or is that the pumped hydro / big batteries / future technology stuff?
[Sorry for going off topic, here]
But weather can span large areas and the solutions can be roughly categorized as:
- some form of energy storage: batteries, hydro (can be pumped), flywheels, etc
- dispatchable power - gas fired turbines, coal or wood fired thermal plants, nuclear, etc
- demand side response - time of use pricing (like nordpool spot market prices) or getting paid to switch off your AC during peak hours, etc.
Traditionally we have had a grid management mindset of "generation adapts to load", everyone uses as much and when they need and grid/generation adapts to it.
With only renewables the mental model of "load follows generation" could make sense, people (or rather peoples devices) get a signal when it is most beneficial to consume and when not to.
I think the reality will be some combination of all of the above. Mostly renewables but also diverse set of renewables that are somewhat anti-correlated, like wind+solar plus distributed. The shortfalls could be filled with natural gas fired power plants. Some nuclear when/if built/available combined with smart cars and devices. V2G will get there eventually as well and then the car battery will have much more energy available than a typical home uses in a day.
Cruachan to the rescue.
https://en.wikipedia.org/wiki/Cruachan_Power_Station
Zero to full production in two minutes, 30 seconds in an extreme case if required. It's the Power Infrastructure equivalent of a supercar.
That's why the grid will selectively island parts that are too far out of phase. Normally this should not happen though.
Sigh…
The article mentions the critical parameters which historically have been sourced from big heavy generators like hydro, coal, nuclear or CCGT plants:
- Frequency regulation: When grid power crashes or surges, the device immediately releases or absorbs energy to minimize fluctuation in the AC frequency;
- Short circuit power: When the grid experiences a short circuit, the crashing voltage releases a tripling or more of current from rotating machines which signals breakers on the grid to activate and quickly isolate the fault;
- Voltage support: Producing current and voltage that are out of phase generates so-called reactive power that pushes the local grid’s voltage up or down to stabilize system voltage and/or increase the flow of real power.
This is about Inertia and frequency control. Not about bulk energy storage.