On Oct 13, 2013, at 7:46 AM, jiji aminudin <[email protected]> wrote: > Dear all, > > I’m using Matpower to run load flow for IEEE-24 bus system. I would > appreciate if anybody can help me on the followings: > > 1) I just wonder why the difference between buses’s sending power and buses’s > receiving power (for branch) doesn’t tally with the resulted line losses? For > example (please refer to highlighted area in the attachment), at branch 1, > bus 1 is sending 11.94-j26.92MVA and bus 2 receives -11.94-j22.45MVA. > Logically, the losses will be 0-j4.47MVA > ([11.94-j26.92MVA]-[-11.94-j22.45MVA]). But, the resulted line loses > connecting the two buses are 0.004+j0.02MVA. Is that possible? > The losses that are reported are only the series losses (I^2 * Z) and do not include the reactive power injected by the line-charging elements of the transmission model. This is simply a matter of defining clearly which losses you are including. You will notice that in the System Summary section of the output, the Losses are reported separately from the Branch Charging. > 2) Is anybody here working on the same system as I am? Can you help me to > verify the result (please refer to attachment)? > > 3) I’ve compared the result with other load flow software. It seems that the > voltage magnitude and active power losses do not differ much. But, the > voltage angle and reactive power losses vary significantly. Isn’t all the > results should be approximately the same? > The voltage angle results should be exactly the same assuming the input data is identical. The loss numbers may be different if other load flow software lumps the branch charging together with the series losses, otherwise they should also be identical.
-- Ray Zimmerman Senior Research Associate B30 Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645
