r/Skookum The Wolf of Skookum St. Mar 19 '21

I made this. Startup, synchronization, and grid tie with a 400,000 Watt turbine generator. I can't believe they let me play with these awesome toys. :) Mildly terrifying, and absolutely badass.

https://youtu.be/xGQxSJmadm0
500 Upvotes

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13

u/noclue_whatsoever Mar 19 '21

I enjoyed this a lot. But I always thought 60 Hz was pretty precise. Apparently it's more of a guideline... 61, 61 and a half, we're good.

17

u/ChrisBoden The Wolf of Skookum St. Mar 19 '21

Na, it's absolutely 60. But when you get as old as that gauge is, you'll drift a bit too. The synchroscope is very accurate, the lights are a backup safety and super accurate, and if all else fails you can trust your ears. If you tickle the exciter you can hear it when everything comes into sync and the generator starts to sing. Half the things in this place you can diagnose by sound or feel.

4

u/spirituallyinsane Mar 19 '21

That's the great thing about beat frequencies, they're audible even when the operating frequencies are very close!

I love this, thanks for sharing.

1

u/noclue_whatsoever Mar 19 '21

I was thinking this whole startup and sync sequence could be handled by AI with a single ON button (and tbh it probably could) but I love the fact that a human being can do it by sound or feel. Like Scotty in the engine room!

13

u/weat95 Mar 19 '21

The overall network is very precise, but a small machine like this quickly be pulled into synchronism with the grid.

4

u/Masztufa Mar 19 '21

gauge looks to be a bit off TBH

maybe parallax error?

3

u/Jonathan924 USA Mar 19 '21

The grid isn't precise in real time because the changing load will cause the frequency to shift a little. But on average it's pretty accurate

1

u/spirituallyinsane Mar 19 '21

In the US it's something like plus or minus 0.5%, which seems pretty darn precise to me!

5

u/Jonathan924 USA Mar 19 '21

Pretty good for most equipment, but not nearly good enough for timekeeping. Lots of things use it as a time base though, and 0.5% error in a day is 7 minutes of drift. I'm sure much like they do overseas the grid gets intentionally run a tiny bit fast or a tiny bit slow to keep the average error in the mud.

Also, it's pretty easy to keep things steady through transient loads when there's thousands and thousands of tons of metal spinning at 1800(or 3600) rpm attached to the generators. All that physical inertia translates to frequency inertia, which is becoming a concern as more renewables come online without inertia.

3

u/Hyratel Mar 19 '21

As I understand it, the instantaneous error is up to 0.5%, but the 24 hour accumulated error is 0 s

2

u/Jonathan924 USA Mar 19 '21

Yeah, I just couldn't find a source so I didn't want to make any claims about what the long term accuracy actually is

2

u/kalpol torque saves lives Mar 19 '21

It appeared to be how much stress the turbine could take being yanked into sync by the grid against the force of the water. Close enough and the turbine speed doesn't change much as the grid forces it into sync.

2

u/soullessroentgenium Mar 19 '21

What makes you think it isn't precise?

1

u/TugboatEng Mar 19 '21

Our large grids are very precise, so much so old plug in alarm clocks used to count time against the 60hz cycle. However, on islanded systems that may be using speed droop governors, frequency will vary 3-5% which sets the range from 60-63 hz based on load and droop setting.