4 ms·

Umm, can you expand on wind turbines being energy sinks in a way solar cannot?

p_l 2y ago
Solar panels essentially give you DC output from light hitting them. You can't make a sink out of it in any way. You cannot connect power to solar panel and make it generate light or otherwise consume it (other than maybe melting it ;)) Wind turbines however provide rotational energy that has to be turned into electricity. Modern turbines use somewhat complex alternators, often with multiply of 3 phases, which is normally used to provide delicately adjusted power output in sync with the grid. Fine adjustments of phase skew are usually used to control power provided to the grid and to keep generated power in phase with the grid. However, such alternator can be driven in a way where the electricity provides braking power. You can think of it as similar to how many electric engines are both generators and sinks. It's however way more fine tuned than toy examples.
- vel0city 2y ago
  Due to the high variance of rotational speed I don't think most wind turbines are directly AC connected to the grid. From what I've read they often go AC -> DC -> AC so they can actually frequency match reliably.
  - p_l 2y ago
    The cost and inefficiency of DC conversion for the power-generation part is why new turbines use DFIGs[1]. Essentially it allows keeping chosen frequency despite changes in turbine power, and is core to tricks like I described. [1] https://en.wikipedia.org/wiki/Doubly_fed_electric_machine#Doubly_fed_induction_generator https://en.wikipedia.org/wiki/Doubly_fed_electric_machine#Do...
    - vel0city 2y ago
      That seems pretty cool. Good to hear they're rolling out newer tech to solve that DC conversion and have turbines help support frequency. Thanks for sharing! I wonder what percentage of turbines installed already have this technology versus the DC conversion. Or are pretty much all MW scale turbines using this?
      - p_l 2y ago
        Apparently they are quite common, but permanent magnet synchronous motors with double inverters are apparently increasingly common, though even there I've heard of similar tricks with polyphase winding as well as electronically "feeding in" power onto each phase to achieve whichever goals plant control wants.
        vel0city 2y ago
        Neat, time for me to do a good bit more reading it seems. I appreciate the insights you brought. As an aside, I find it funny so much of our power grid can have so many complicated parts but often boils down to boils down to "big thing spin fast!"
        p_l 2y ago
        Personally the funniest to me is UK's Supergrid dispatch centers watching BBC to synchronize extra power capacity with ending credits of various popular shows. Because otherwise the millions of 2kW electric kettles result in turbines visibly slowing and grid failure :D
- ZeroGravitas 2y ago
  Solar PV inverters can also provide similar services to the grid. https://www.sciencedirect.com/science/article/pii/S2352484722008502 https://www.sciencedirect.com/science/article/pii/S235248472... Title: "Using PV inverters for voltage support at night can lower grid costs"
- itishappy 2y ago
  > You can't make a sink out of it in any way. Sure you can, just drive 'em at a higher reverse voltage and they'll emit IR light instead. https://www.youtube.com/watch?v=6WGKz2sUa0w https://www.youtube.com/watch?v=6WGKz2sUa0w
  - p_l 2y ago
    TIL! Thanks

p_l 2y ago

Solar panels essentially give you DC output from light hitting them. You can't make a sink out of it in any way. You cannot connect power to solar panel and make it generate light or otherwise consume it (other than maybe melting it ;)) Wind turbines however provide rotational energy that has to be turned into electricity. Modern turbines use somewhat complex alternators, often with multiply of 3 phases, which is normally used to provide delicately adjusted power output in sync with the grid. Fine adjustments of phase skew are usually used to control power provided to the grid and to keep generated power in phase with the grid. However, such alternator can be driven in a way where the electricity provides braking power. You can think of it as similar to how many electric engines are both generators and sinks. It's however way more fine tuned than toy examples.

vel0city 2y ago
Due to the high variance of rotational speed I don't think most wind turbines are directly AC connected to the grid. From what I've read they often go AC -> DC -> AC so they can actually frequency match reliably.
- p_l 2y ago
  The cost and inefficiency of DC conversion for the power-generation part is why new turbines use DFIGs[1]. Essentially it allows keeping chosen frequency despite changes in turbine power, and is core to tricks like I described. [1] https://en.wikipedia.org/wiki/Doubly_fed_electric_machine#Doubly_fed_induction_generator https://en.wikipedia.org/wiki/Doubly_fed_electric_machine#Do...
  - vel0city 2y ago
    That seems pretty cool. Good to hear they're rolling out newer tech to solve that DC conversion and have turbines help support frequency. Thanks for sharing! I wonder what percentage of turbines installed already have this technology versus the DC conversion. Or are pretty much all MW scale turbines using this?
    - p_l 2y ago
      Apparently they are quite common, but permanent magnet synchronous motors with double inverters are apparently increasingly common, though even there I've heard of similar tricks with polyphase winding as well as electronically "feeding in" power onto each phase to achieve whichever goals plant control wants.
      - vel0city 2y ago
        Neat, time for me to do a good bit more reading it seems. I appreciate the insights you brought. As an aside, I find it funny so much of our power grid can have so many complicated parts but often boils down to boils down to "big thing spin fast!"
        p_l 2y ago
        Personally the funniest to me is UK's Supergrid dispatch centers watching BBC to synchronize extra power capacity with ending credits of various popular shows. Because otherwise the millions of 2kW electric kettles result in turbines visibly slowing and grid failure :D
ZeroGravitas 2y ago
Solar PV inverters can also provide similar services to the grid. https://www.sciencedirect.com/science/article/pii/S2352484722008502 https://www.sciencedirect.com/science/article/pii/S235248472... Title: "Using PV inverters for voltage support at night can lower grid costs"
itishappy 2y ago
> You can't make a sink out of it in any way. Sure you can, just drive 'em at a higher reverse voltage and they'll emit IR light instead. https://www.youtube.com/watch?v=6WGKz2sUa0w https://www.youtube.com/watch?v=6WGKz2sUa0w
- p_l 2y ago
  TIL! Thanks