[Bldg-sim] Dynamic demand

[JRR]

John Ross wrote;

I think you will find the frequency and phase of the electric power grid 
very tightly controlled.
I really doubt that you will get a meaningful quantitative measurement. 
A qualitative measurement
might indicate current general problems on a particular section of the 
power grid.

As part of a senior level power plant design class in 1980 we visited a 
then already old coal
fired power plant. To adjust the phase of  the generator versus the grid 
they used a bridge with
two light bulbs. When both light bulbs were equally dim they remotely 
threw the generator mains
online. Well the week before our visit they had both light bulbs burn 
out at the same time during
an initialization.    Very fortunately it happened on the third shift 
and the place was just about deserted.
We saw many many low pressure stage turbine blades 48+ inches long 
embedded in the concrete
walls. That was just from a  ~ 10 degree or less miss match...
By the way, I never sit opposite the engines when I travel by air......


David Bradley wrote:
> Chris,
> Two things come to mind. We've done something similar in simulating 
> grid-tied power systems that include some renewable sources (wind and 
> pv), a battery bank, an electrolyzer, a fuel cell, and a grid that is 
> sometimes unavailable. The controls sense (among other things) the 
> availability of the grid and act accordingly. I am also aware of some 
> work being done at Penn State on a pv/battery system that knows what 
> the utility rates are at the current time. Again the controls make a 
> decision about whether to meet the load with the PV or with the grid 
> based on something that is going on in the grid at the current time. 
> Both projects were done using TRNSYS.
> Kind regards,
> David
>
>
> Chris Yates wrote:
>> Just out of interest really...
>>
>> Does anybody have any experience of modelling dynamic demand systems. 
>> For example, a heat pump might "listen" to the frequency of the 
>> electricity grid (lower frequency represents large concurrent demand) 
>> and adjust it's demand down accordingly.
>>
>> It just seems like an interesting modelling exercise and I was 
>> wondering if anybody has had any success and with which software.
>>
>> Cheers
>>
>> Chris
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