DISPATCHINTERCONNECTORRES MWLOSSES

[Matthew Davis]

Hi,

Can anyone explain to me how the signs for MWLOSSES are supposed to work?

The wiki says:

> Note that there are records with all 4 pairings of negative/positive MWLOSSES and negative/positive MWFLOW.

The AEMO documentation says:

"MW losses can be negative depending on the flow.

The definition of direction of flow for an interconnector is that positive flow starts from the FROMREGION in the INTERCONNECTOR table."

I'm not sure how to interpret the sign of MWLOSSES when MWFLOW (or METEREDMWFLOW) is negative.

Can someone help me complete these examples (replace the ? with a real number)

Suppose this is for an interconnector from region A to region B

1. MWFLOW=+5, MWLOSS=+1, 5 MW of power from A into the transmission line, 5-1=4 MW leaves the transmission line and enters region B. Or is it 5+1=6MW into the line and 5MW out?
   
2. MWFLOW=+5, MWLOSS=-1, 5 MW of power from A into the transmission line, 5--1=6 MW leaves the transmission line and enters region B. (Somehow we've got free energy?)
3. MWFLOW=-5, MWLOSS=+1, ? MW of power from B into the transmission line, ? MW leaves the transmission line and enters region A
4. MWFLOW=-5, MWLOSS=-1, ? MW of power from B into the transmission line, ? MW leaves the transmission line and enters region A

Thanks,
Matthew

[Nicholas Gorman]

Hi Mathew,

My understanding, mostly glend through developing Nempy, is:

1. Losses are effectively added as additional load in the two
connected regions, with losses split according to the loss share
factors, see the table INTERCONNECTORCONSTRAINT. So the flow into and
out of each region is just MFLOW.

2. Losses can be negative because AEMO models losses as a quadratic
function fit to historical empirical loss data, sometimes the best fit
of the function to the data gives small negative values when the flow
is small. See this doc for more details:
https://github.com/UNSW-CEEM/nempy/blob/master/docs/pdfs/Marginal%20Loss%20Factors%20for%20the%202020-21%20Financial%20year.pdf,
section 4. In this case, yes, the losses would appear as additional
generation in the connected regions, free energy!!!!

3. This example from nempy might be helpful:
https://nempy.readthedocs.io/en/latest/examples.html#interconnector-with-losses

4. Even deeper dive it how losses are modelled (assuming nempy gets it right):
https://nempy.readthedocs.io/en/latest/markets.html#nempy.markets.SpotMarket.set_interconnector_losses

Cheers,
Nick

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[Matthew Davis]

Ah, it's even more complicated than I expected, ha.

Ok, I think I get it now. Thanks for the quick response!

Regards,
Matt