Hi Richard, Your question prompted me to go back and review this stuff.
It turns out the LCDF_ij is equal to the negative of the PTDF for a transaction from the from to the to end of the line you intend to close (from page 13 of Overbye’s lect 17). And that is using the PTDF computed from the pre-closure network. Furthermore, it does equal the negative of the LODF_ij computed from the post-closure network. Ray On Sep 1, 2022, at 6:02 AM, Richard Lincoln <[email protected]<mailto:[email protected]>> wrote: Hi Ray, The only definition I was able to find is from the lecture slides of Professor Tom Overbye at Texas A&M University: https://overbye.engr.tamu.edu/wp-content/uploads/sites/146/2018/10/ECEN615_Fall2018_Lect17.pdf#page=11 LCDF_ij is the portion of the active power flow in branch j (the flow that will occur when the branch j is closed (which we do not know)) that is distributed to branch i due to the closure of branch j. Using the negative of the post-closure LODF makes sense to me, but the slides mention the insertion of an "additional basic transaction" that I couldn't quite understand. Perhaps it refers to reinstating the open branch before computing the LODF. I will try testing against results from PowerWorld and see if the -LODF approach works. Richard On Wed, 31 Aug 2022 at 22:57, Ray Daniel Zimmerman <[email protected]<mailto:[email protected]>> wrote: Hello Richard, Do you know the precise definition of the LCDF? The LODF_ij is the change in flow in branch i resulting from a branch j outage as a fraction of the pre-outage flow on branch j. So would the LCDF_ij be the change in flow in branch i as a result of a branch j clousre as a fraction of the post-closure flow on branch j?* If so, it would seem that the LCDF is equal to the negative of the LODF computed on the post-closure network, right? I suspect there is a more efficient way to compute LCDFs if you already have the PTDFs for the pre-closure system, but I haven’t found a formula for it or derived it myself (yet). Ray * Seems that’s exactly how PowerWorld describes it on page I11-19 of this Linear Analysis trainman document<https://www.powerworld.com/files/TrainingI11LinearAnalysis.pdf>. On Aug 30, 2022, at 10:12 AM, Richard Lincoln <[email protected]<mailto:[email protected]>> wrote: I am able to use the makeLODF function from MATPOWER to calculate the changes in flows given the outage of a branch. However, I would like to be able do the same, but for the reconnection of a branch that is presently open. I've heard these referred to as Line Closure Distribution Factors (LCDF). Does anyone know how they might be computed with MATPOWER? Richard
