Sorry, the ‘halved" and “doubled” language was confusing, except in the context of identical parallel lines.
For lines with parameters r1, x1, b1 and r2, x2, b2, the equivalent values for the parallel set would be rt, xt, bt, where … rt = 1 / (1/r1 + 1/r2) xt = 1 / (1/x1 + 1/x2) bt = b1 + b2 So I think the first alternative in your example is correct, except for multiplying b by 2. You can also easily check by running a power flow before and after consolidating the lines. You should get exactly the same solution if you did it correctly. Hope this clarifies, Ray On Apr 19, 2021, at 11:37 AM, naime ahmadi <naimeahm...@gmail.com<mailto:naimeahm...@gmail.com>> wrote: Dear Professor Zimmerman, Thank you for your time. Please confirm if my understanding is correct. For this duplicate branch 77 80 0.017 0.0485 0.0472 0 0 0 0 0 1 -360 360; 77 80 0.0294 0.105 0.0228 0 0 0 0 0 1 -360 360; 1/r_t =1/ 0.017 +1/ 0.0294 ---> r_t=0.0108 OR r_t = (0.017 + 0.0294)/2 ---> r_t=0.0232 1/x_t =1/ 0.0485 +1/ 0.105 ---> x_t=0.0332 OR x_t =(0.0485 + 0.105)/2 ---> x_t=0.07675 b_t= (0.0472 + 0.0228)*2 ---> b_t=0.14 so the equivalent branch is 77 80 0.0108 0.0332 0.14 0 0 0 0 0 1 -360 360;360; OR 77 80 0.0232 0.07675 0.14 0 0 0 0 0 1 -360 360;360; Kind Regards, Naime On Tue, Apr 20, 2021 at 1:09 AM Ray Daniel Zimmerman <r...@cornell.edu<mailto:r...@cornell.edu>> wrote: In general, the line ratings RATE_A, etc, would also equal the sum of the individual line ratings, but in this case the capacity limit is not given (interpreted as unlimited) so no change. However, a quick correction … while the total impedance (r and x) are halved, the total line charging (b) is doubled. Ray On Apr 19, 2021, at 9:59 AM, naime ahmadi <naimeahm...@gmail.com<mailto:naimeahm...@gmail.com>> wrote: Hello Matpower users, I want to remove duplicate branches in IEEE 118 bus system and put an equivalent one. For example: fbus tbus r x b rateA rateB rateC ratio angle status angmin angmax duplicate branches: 42 49 0.0715 0.323 0.086 0 0 0 0 0 1 -360 360; 42 49 0.0715 0.323 0.086 0 0 0 0 0 1 -360 360; equivalent branch: 42 49 0.0357 0.1615 0.0430 0 0 0 0 0 1 -360 360; Is it sufficient to only change r, x and b to equivalent one or do I need to have more changes? Thanks, Naime
