[time-nuts] Yukon Energy causes time sync problems

Matthew Kaufman matthew at matthew.at
Sat Apr 10 11:55:51 EDT 2010


If your generation isn't tied to a wider-area grid, all you really  
care about is coarse instantaneous frequency and keeping the long-term  
average as precise as possible, the latter is specifically so your  
customers' clocks run at the right speed.

The former is doable with reeds, the latter requires exactly the kind  
of integration over time that a clock compared with another time  
reference provides... This is just a PLL with a minutes-to-hours time  
constant and human phase comparators controlling the generator speed.

Matthew Kaufman

(Sent from my iPhone)

On Apr 10, 2010, at 8:31 AM, Eric Garner <garnere at gmail.com> wrote:

> My question is why is it done that way at all? It seems impractical  
> in the extreme. Why not use a meter? Or the afore mentioned  
> vibrating reeds?
>
> What happens when the clock rates sync up again, since the wall  
> clock time will still be ahead/behind the sat clock? Do they reset  
> the wall clock? Or is it only the rate that matters?
>
> Given the sophistication of the rest of the network there must be a  
> reason.
>
> Sent from my Banana Jr. mobile device
>
> On Apr 8, 2010, at 3:48 PM, "Bill Hawkins" <bill at iaxs.net> wrote:
>
>> Brooke,
>>
>> There are some interesting misconceptions here.
>>
>> Yukon Power did not cause time to slow down. They did what every  
>> generating
>> station does, which is to adjust drive power to make a synchronous  
>> power
>> line
>> clock match a precision reference clock. The tolerance is seconds  
>> because
>> the
>> means for controlling drive power has a time constant of several  
>> seconds.
>>
>> The real problem is the way demand varies. If you pour mechanical  
>> power into
>> a generator, it will speed up when lightly loaded or slow down when  
>> heavily
>> loaded. This is less of a problem when many generators are tied  
>> together by
>> a power grid, as they are all synchronous machines. Central  
>> dispatching
>> stations compare line and reference clocks, and direct plants with  
>> capacity
>> to do so to make up lost cycles, or buy less from the most  
>> expensive sources
>> when extra cycles are generated.
>>
>> If you have a 5 digit counter (or more) tied to a computer, you can  
>> plot the
>> deviation of line frequency for 24 hour intervals. TVB had this on  
>> his site.
>> What I saw in MN was that generators speeded up in the early  
>> morning to make
>> up cycles so there was no reference error at 6 AM. Then the loads  
>> turned on
>> and the cycles fell behind and recovered as power was dispatched,  
>> within +/-
>> 6 seconds. This is good enough for social time, where the mundanes  
>> don't
>> know
>> about time-nuts.
>>
>> The Alaskan network is probably too sparse for central direction,  
>> so each
>> power plant makes its own adjustments. Note that this doesn't  
>> necessarily
>> produce stable control, ever.
>>
>> In this case, the reference clock appears to refer to GPS satellite  
>> time,
>> but
>> uses a standard wall clock to display it. It is the reference clock  
>> that
>> slowed down when it should have failed to work at all. Perhaps the  
>> wall
>> clock
>> (maybe it was really a HP 113) needed oil. There's the real  
>> question for
>> time
>> nuts: How did the reference clock slow down?
>>
>> The first comment to the article shows what happens when your ego  
>> fails to
>> shame you into silence when you don't know what you're talking about:
>>
>> "I don't understand how the amount being generated has anything to  
>> do with
>> what happens to household electronics." [see above]
>>
>> "It would make more sense if the plant was generating at 55Hz  
>> versus 60Hz
>> as some electronics will use the line frequency rather than  
>> integrated
>> oscillators to set clocks." [The plant probably has breakers that  
>> take it
>> off line when the frequency gets below 58 cycles, to keep it from  
>> dragging
>> the network down.] [I thought that all electronics today converted  
>> the line
>> to DC without sampling it, and ran timing from a crystal. Anyone  
>> know?]
>>
>> "Regardless, it shows YEC continues to be a bunch of bumbling  
>> oafs." [People
>> who live in glass houses shouldn't stow thrones, or something like  
>> that.]
>>
>> Thanks, Brooke. I had some fun explaining all this.
>>
>> Bill Hawkins
>>
>>
>> -----Original Message-----
>> From: Brooke Clarke
>> Sent: Thursday, April 08, 2010 12:58 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: [time-nuts] Yukon Energy causes time sync problems
>>
>> Hi:
>>
>> http://whitehorsestar.com/archive/story/time-passed-more-slowly-over-the-eas
>> ter-holiday/
>>
>> -- 
>> Have Fun,
>>
>> Brooke Clarke
>> http://www.PRC68.com
>>
>>
>>
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