I’m afraid I don’t have any details on how these particular parameters were calculated, but I would not be surprised if any physically unrealistic values arise from equivalencing. I think there may be some negative resistances in some of the cases as well, which I’m pretty sure comes from equivalencing.
Ray On Nov 25, 2021, at 1:17 PM, Liang Chen <[email protected]<mailto:[email protected]>> wrote: Dear all, I noticed some lines with very high (1.0 and above) R/X values in certain test cases For example, 1. in case300.m, branches * (9021, 9023) R/X ratio = 1.1617 * (9003, 9044) R/X ratio = 1.1615 * (9044, 9004) R/X ratio = 1.3241 2. in case2869pegase.m, branches * (3095, 2951) R/X ratio = 1.8244 * (8209, 1998) R/X ratio = 1.4405 * (1216, 5233) R/X ratio = 1.1316 * (4318, 1338) R/X ratio = 1.0228 * (6047, 5271) R/X ratio = 1.0783 * (6047, 5271) R/X ratio = 1.5017 I'm wondering why this is the case and whether they are physically realistic. I'm working on an iterative power flow algorithm and have found that high R/X ratio (1.0 and above) in the branches causes my iterations to diverge, so I want to decide between going back and revise the theory, or to simply put a footnote, e.g., "R/X ratio should not be too high." Numerically, capping these lines at R/X = 0.999 still allows for convergence, but more slowly as the maximum gets closer to 0.999. Best regards, Jeffrey Chen
