[time-nuts] Daft idea with the National Grid

[joekokker at epios.eu]

Dear all,

it is quite an interesting premise. I think one of the challenges is to 
even measure these small deviations in frequency. The time correlation 
can be achieved with GNSS but the actual determination of the 
zero-crossing might be the problem. I think the ZCD must be better than 
100ns for this in each cycle. Local noise and environment conditions 
render it quite difficult. When constructing a filter for the 50Hz, the 
components must be very well designed to cope with the different 
temperature, local noise and voltage amplitudes at two different places.

Regarding disruptions in the grid: there are various regulation 
mechanisms. Generally the first 10-20 seconds physical effects stabilize 
the grid. Afterwards the automatic control takes over.

- saved rotational energy: an initial frequency drop due to a unexpected 
change in load or production is smoothed out by the inertia of all the 
generators, motors, pumps, etc. For a 10% mismatch in power without 
additional measures, the initial frequency drop would be about 1Hz per 
30 seconds.

- self-regulation: a 1% drop in frequency leads to a ~2% reduction of 
load due to frequency dependent loads;

- primary, automatic load-frequency control takes about 30 seconds to 
activate

After this rather short timescales, as Poul-Henning mentioned the human 
factor (trading) has the biggest impacts on grid stability. It is 
clearly visible with a periodicity of 15 minutes and more pronounced in 
the evenings.

A small note on the recent frequency drop in the European grid:
https://www.entsoe.eu/news/2021/01/26/system-separation-in-the-continental-europe-synchronous-area-on-8-january-2021-2nd-update/

Best
Joe

On 2/8/21 8:46 PM, Mark Spencer wrote:
> Years ago I recall reading accounts of efforts in the U.S. and perhaps Canada to track down the cause(s) of small but noticeable changes in the frequency of certain regional power grids that seemed to occur at more or less the same time each day.
> 
> 
> Mark Spencer
> mark at alignedsolutions.com
> 604 762 4099
> 
>> On Feb 8, 2021, at 6:48 AM, Lux, Jim <jim at luxfamily.com> wrote:
>>
>>> On 2/8/21 12:02 AM, Poul-Henning Kamp wrote:
>>> --------
>>> Lux, Jim writes:
>>>
>>>> If you happen to own something like a steel mill running electric
>>>> furnaces or an aluminum refinery, so you can manipulate the load...
>>> More scary:  Several independent studies have shown that even relatively
>>> moderate bot-nets in the hands of somebody who knows the math of grid
>>> stability would mean no grid stability.
>> This is a generalized concern with distributed generation (i.e. rooftop solar panels on houses), because a bug in the controllers for the line connected inverter could really screw things up. I suppose there's also concerns about  malicious activity, but fiascos like the NEST thermostats stopping  in winter of 2015/2016 are more likely.
>>
>>
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