It is possible for the active power injections into both ends of a branch to be positive, meaning there are active power losses in the line even though the active “flow” is nearly zero. Presumably this is due to the currents involved in the reactive power injections. I do not think it is possible for the active power injections into both ends of a line to be negative, unless it has a negative resistance. And I can’t think of a physical meaning for negative series resistance in a branch.
-- Ray Zimmerman Senior Research Associate B30 Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645 On Oct 30, 2013, at 5:34 PM, spyros gian <[email protected]> wrote: > Dr Zimmerman, > I would like to share with you an interesting observation. > Suppose a line connecting bus 1 and bus 2. > The power comes out of bus1, and goes into bus 2. So, 10MW come out of bus1, > and 8MW go into bus2. > The 2 MW is losses. > This sounds logical. > > However, there are cases in multibus systems, where across a line K-L, the > flow coming out of busK is 10MW > and the flow coming into busL is - 8MW. So in this case busK sends 10MW and > busL sends 8MW. > Is there a meaning in this? > > Also, there are cases where both powers are negative. > > I haven't got the files to send them to you, but in my experience I have seen > such cases occur with MatPower, though > I do not remember the versions. > > So the question is generalized into : > Can there be cases where the power that comes out of one bus and goes into > another bus of the same line, are of the same sign? > Is there any physical meaning into this ? > > Thank you > Syros Gian
