Then run parts at 105-110% and it gets really hard.
The power industry designs a grid that runs so close to capacity that if^W when something big fails, the whole grid shuts down in a cascade. They know it:
Rubbish again.
Welcome to the wonderful world of physics. Ask your favourite physics professor what does
E1 = E2
in context of yesterdays events.
That's not really answering the question, and it's also not entirely right. For one, even if we naively accept sum(Eproduced) = sum(Econsumed), that says nothing about the amperage which can safely traverse parts of the grid intertie wiring, switching facilities, etc. If *those* are running at or slightly over capacity, and in particular of all those facilities don't have at least N+1 and preferably N+M redundant actual capacity, then a single point failure will produce a fatal cascading failure in the system. That appears to be what happened. For two, most of the things that consume power are not in fact consuming exactly a fixed amount of power. Light bulbs go dimmer if you reduce voltage; electrical motors will produce less power (torque X rpm) if voltage drops, etc. Minor blips are happening all the time in major grids, and the voltage is continuously varying up and down slightly. If we had to keep voltage exactly constant, a real AC power system would be nigh-on impossible to build. Our concerns with electrical capacity in terms of the interchange grids having N+1 or N+M capacity, and having systems with enough robustness and graceful failure modes, and having systems with enough reserve generation capacity are all legitimate. A lot of other people are looking at that now, too. But you *can't* just simplify this to Ein = Eout. -george william herbert gherbert@retro.com
For two, most of the things that consume power are not in fact consuming exactly a fixed amount of power. Light bulbs go dimmer if you reduce voltage; electrical motors will produce less power (torque X rpm) if voltage drops, etc. Minor blips are happening all the time in major grids, and the voltage is continuously varying up and down slightly. If we had to keep voltage exactly constant, a real AC power system would be nigh-on impossible to build.
Part of the problem is that an increasing fraction of the grid will actually draw more power as the voltage decreases. Switching power supplies will maintain a constant output power provided their input voltage remains in a reasonable window. Their efficiency is generally the highest at their design nominal volatage. So a decrease in volage will require them to draw more current both because more is needed for the same power and they'll need more power. As more and more of the load becomes 'smart', the resiliency starts to go out of the system. To some extent, the same is true of things like cooling systems. As the voltage drops, their duty cycle will increase, though this problem manifests itself over a slightly longer term. And, of course, you can't keep the voltage constant. It's the differences in voltage that make the current flow. DS
Then run parts at 105-110% and it gets really hard.
The power industry designs a grid that runs so close to capacity that if^W when something big fails, the whole grid shuts down in a cascade. They know it:
Rubbish again.
Welcome to the wonderful world of physics. Ask your favourite physics professor what does
E1 = E2
in context of yesterdays events.
That's not really answering the question, and it's also not entirely right.
[skip]
But you *can't* just simplify this to Ein = Eout.
No, it is spinning physics that does not work - physics *is* simple as long as one does not skip the linkage between different things: Econsumed = Econsumed_productive + Qreleased + Wreqired Econsumed_productive is what you actually used Qreleased is the energy released in a form of a increase/decrease heat Wrequired is the work required to get Econsumed. Alex
participants (3)
-
alex＠yuriev.com -
David Schwartz -
George William Herbert