4 ms·

Okay, but what if you are at point A, and connected to points B and C, which are 1000 km away from you and also 1000 km away from each other, and connected to e

by gpvos 9y ago

Okay, but what if you are at point A, and connected to points B and C, which are 1000 km away from you and also 1000 km away from each other, and connected to each other. Now if you would synchronize with B and C, then seen from the sky B and C would be in sync with each other because they're at the same distance from you. But how would B and C then transfer power over the 1000 km link between each other without phase problems?

TheRealPomax 9y ago
Remember that power stations do not generate the same single phase signal that you tap into in your house. They generate three phase AC current. They also don't link up directly: there are transmission substations in between.
- wintermutesGhst 9y ago
  This is what I wondered, is network topology carefully arranged to avoid triangular connections, or 'loops' where a generator could interfere (indirectly) with itself?
  - neltnerb 9y ago
    Nope! They're connected in triangles all the time. I was stuck on this phase synchronization for a while, but really it's just the local phase lead or lag that is required. Think of the phase as a distributed signal that indicates the current state of the local system taking into account all connected generators. It's weird but true!
    - gpvos 9y ago
      Can you elaborate? It is still unclear to me.
      - neltnerb 9y ago
        I may be explaining it wrong, but here is a reference, particularly 22.8: https://www.scribd.com/doc/118169687/Network-Protection-Automation-Guide-NPAG-2011-alstom https://www.scribd.com/doc/118169687/Network-Protection-Auto... This makes it sound more complex than what I learned when I last tried to figure it out =) They seem to be describing that where two grids meet they go through a synchronizer that disconnects one or the other if they aren't in sync, so implies manually disconnections throughout the network as needed locally.
  - dfox 9y ago
    Today the physical topology is usually somewhat random mesh, but not all interconnection lines are active at the same time. In early days of electrification the physical topology usually was spanning tree and in fact this was the motivation for research into minimal spanning tree algorithms at the time.
- wyager 9y ago
  That doesn’t answer his question.
mjevans 9y ago
Short version: it doesn't. It's like a very long pipe with standing water in it. AC power is like attaching a pump column at one point and adding/removing pressure at just that point. This creates a /wave/ of energy that propagates, but the actual water (electrons) do not. It's more accurate to say they vibrate. Continuing the metaphor, power plants increase the amplitude of this sloshing wave, and must be synchronized to the phase of the wave /where they connect/ (in order to be additive instead of subtractive). Consumers of the power are always subtractive, '(active/passive) power factor correction' in switching power supplies is about attempting to keep the consumption timed for efficiency. AC Motors are continuous users and mostly just draw all the time.

by gpvos 9y ago

TheRealPomax 9y ago

Remember that power stations do not generate the same single phase signal that you tap into in your house. They generate three phase AC current. They also don't link up directly: there are transmission substations in between.

wintermutesGhst 9y ago
This is what I wondered, is network topology carefully arranged to avoid triangular connections, or 'loops' where a generator could interfere (indirectly) with itself?
- neltnerb 9y ago
  Nope! They're connected in triangles all the time. I was stuck on this phase synchronization for a while, but really it's just the local phase lead or lag that is required. Think of the phase as a distributed signal that indicates the current state of the local system taking into account all connected generators. It's weird but true!
  - gpvos 9y ago
    Can you elaborate? It is still unclear to me.
    - neltnerb 9y ago
      I may be explaining it wrong, but here is a reference, particularly 22.8: https://www.scribd.com/doc/118169687/Network-Protection-Automation-Guide-NPAG-2011-alstom https://www.scribd.com/doc/118169687/Network-Protection-Auto... This makes it sound more complex than what I learned when I last tried to figure it out =) They seem to be describing that where two grids meet they go through a synchronizer that disconnects one or the other if they aren't in sync, so implies manually disconnections throughout the network as needed locally.
- dfox 9y ago
  Today the physical topology is usually somewhat random mesh, but not all interconnection lines are active at the same time. In early days of electrification the physical topology usually was spanning tree and in fact this was the motivation for research into minimal spanning tree algorithms at the time.
wyager 9y ago
That doesn’t answer his question.

mjevans 9y ago

Short version: it doesn't. It's like a very long pipe with standing water in it. AC power is like attaching a pump column at one point and adding/removing pressure at just that point. This creates a /wave/ of energy that propagates, but the actual water (electrons) do not. It's more accurate to say they vibrate. Continuing the metaphor, power plants increase the amplitude of this sloshing wave, and must be synchronized to the phase of the wave /where they connect/ (in order to be additive instead of subtractive). Consumers of the power are always subtractive, '(active/passive) power factor correction' in switching power supplies is about attempting to keep the consumption timed for efficiency. AC Motors are continuous users and mostly just draw all the time.