Dumb question about power transfer losses in PSSE
I'm doing a study where I'm breaking down some components and I got to thinking about something I've never really thought of before.
So I applied a contingency to look at the loading on a transmission line between two buses. I started making some calculations and discovered a few things.
I took the line loading and applied it to the rating. Then I did bus reports on the two buses on either end. What I noticed is that PSSE showed an MVA value exiting the "from" bus that was below the loading on the line applied to the rating of the line. In the bus report, it gives me a loss MW value and MVAR value that derives an MVA value that I assume to be heat losses. Adding this loss power to the power exiting the bus, it makes up the loading on the line applied to the rating on the line.
On the "to" bus, I saw another small drop of about 9 MVA. I'm assuming this is a power transfer loss of some type that is not quite associated with the heat losses of the line.
Initially, my assumption would have been that the % loading on the line would have been the power being transferred by the "from" bus and the power entering the "to" bus would have dropped by the heat losses from the line. This is not the case, so I'm looking for an explanation for this extra loss
Does anyone have any good information about the transfer losses between the two buses besides heat loss? I assume it could be some amount of power reflection due to impedance mismatching, but I'm really curious if anyone might know.
Ive been a power engineer for a little while, but never really formally studied power in school, so I'm sure I'm ignorant to some things. Thanks in advance!