5 ms·

This is why the common trope of "The grid can't function without the inertia from big heavy generators!!" detracting the rise of renewables is invalid. Syntheti

This is why the common trope of "The grid can't function without the inertia from big heavy generators!!" detracting the rise of renewables is invalid. Synthetic grid strength has been available for a century. 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.

sidewndr46 3y ago
this article is about using very high mass alternators to stabilize the grid's frequency
- Retric 3y ago
  The clearest term IMO is synchronous capacitors. They are in effect large flywheels that can operate as both an electric motor and a generator. Over time they are a net power drain for the grid, but as parent says offer synthetic grid stability independent of power sources.
  - repelsteeltje 3y ago
    Very interesting. I'm wondering whether distance and "direction" are an issue here? That is: over large distances (how) would (light speed) latency translate into phase change if "downstream stabilization" suddenly becomes "upstream". (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.
    - jnsaff2 3y ago
      Good instinct. There is a site that measures frequency in several places in Europe and shows the phase difference. [0] 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. [0] https://gridradar.net/charts/map/map.html https://gridradar.net/charts/map/map.html
      - repelsteeltje 3y ago
        So I imagine phase difference can be a serious issue, or at least something that needs to be mitigated and monitored continuously (evidently). I'm assuming a DC power network intrinsically solves this (in case of solar energy). But how would current and voltage be stabilized in that case? Just huge capacitors? Chemical batteries?
        jnsaff2 3y ago
        Frequency and phase difference are indicators of grid balance. 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.
        repelsteeltje 3y ago
        > Grid itself can't store energy, the generation and consumption needs to be in balance. 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]
  - sidewndr46 3y ago
    Why would anyone use the term 'capacitor' to describe what is basically an alternator, a flywheel & an electric motor?
    - callalex 3y ago
      It’s short term energy storage with rapid charge and discharge capabilities. Not all capacitors are electrolytic.
  - connicpu 3y ago
    If we're going to use circuit terminology I think the physics of a flywheel are more like some kind of AC Inductor. DC Inductors resist changes in the flow of current, keeping current flowing even when circuit conditions change. It also helps that the parts of an inductor and flywheel that are in contact with the circuit/grid are coils of wire wrapped around an iron/magnetic core.
  - jacquesm 3y ago
    Transformers also have some of that effect.
- sheepshear 3y ago
  I think the article should not have described a condenser as a generator. It's causing confusion.
- ViewTrick1002 3y ago
  Yep. There are also Shunt Reactors for managing voltage stability. https://en.wikipedia.org/wiki/Variable_shunt_reactor https://en.wikipedia.org/wiki/Variable_shunt_reactor
- deleted 3y ago
  [deleted]
vGPU 3y ago
Yes, the mechanism which can provide power for some 45 seconds is a generator replacement. Sigh…
- ViewTrick1002 3y ago
  We are not talking about the energy balance, we are talking about grid strength/inertia also known as ancillary services. Two orthogonal concepts people tend to mix up. 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.
- hoerensagen 3y ago
  Yes? This is about Inertia and frequency control. Not about bulk energy storage.
- stephen_g 3y ago
  Lucky that has nothing to do with how grid stability works then… We’re talking about frequency correction, reactive power control etc. here!

sidewndr46 3y ago

this article is about using very high mass alternators to stabilize the grid's frequency

Retric 3y ago
The clearest term IMO is synchronous capacitors. They are in effect large flywheels that can operate as both an electric motor and a generator. Over time they are a net power drain for the grid, but as parent says offer synthetic grid stability independent of power sources.
- repelsteeltje 3y ago
  Very interesting. I'm wondering whether distance and "direction" are an issue here? That is: over large distances (how) would (light speed) latency translate into phase change if "downstream stabilization" suddenly becomes "upstream". (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.
  - jnsaff2 3y ago
    Good instinct. There is a site that measures frequency in several places in Europe and shows the phase difference. [0] 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. [0] https://gridradar.net/charts/map/map.html https://gridradar.net/charts/map/map.html
    - repelsteeltje 3y ago
      So I imagine phase difference can be a serious issue, or at least something that needs to be mitigated and monitored continuously (evidently). I'm assuming a DC power network intrinsically solves this (in case of solar energy). But how would current and voltage be stabilized in that case? Just huge capacitors? Chemical batteries?
      - jnsaff2 3y ago
        Frequency and phase difference are indicators of grid balance. 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.
        repelsteeltje 3y ago
        > Grid itself can't store energy, the generation and consumption needs to be in balance. 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]
- sidewndr46 3y ago
  Why would anyone use the term 'capacitor' to describe what is basically an alternator, a flywheel & an electric motor?
  - callalex 3y ago
    It’s short term energy storage with rapid charge and discharge capabilities. Not all capacitors are electrolytic.
- connicpu 3y ago
  If we're going to use circuit terminology I think the physics of a flywheel are more like some kind of AC Inductor. DC Inductors resist changes in the flow of current, keeping current flowing even when circuit conditions change. It also helps that the parts of an inductor and flywheel that are in contact with the circuit/grid are coils of wire wrapped around an iron/magnetic core.
- jacquesm 3y ago
  Transformers also have some of that effect.
sheepshear 3y ago
I think the article should not have described a condenser as a generator. It's causing confusion.
ViewTrick1002 3y ago
Yep. There are also Shunt Reactors for managing voltage stability. https://en.wikipedia.org/wiki/Variable_shunt_reactor https://en.wikipedia.org/wiki/Variable_shunt_reactor
deleted 3y ago
[deleted]

vGPU 3y ago

Yes, the mechanism which can provide power for some 45 seconds is a generator replacement. Sigh…

ViewTrick1002 3y ago
We are not talking about the energy balance, we are talking about grid strength/inertia also known as ancillary services. Two orthogonal concepts people tend to mix up. 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.
hoerensagen 3y ago
Yes? This is about Inertia and frequency control. Not about bulk energy storage.
stephen_g 3y ago
Lucky that has nothing to do with how grid stability works then… We’re talking about frequency correction, reactive power control etc. here!