Dear Professor Zimmerman, Thank you so much for your help. Kind Regard, Naime
On Wed, Apr 21, 2021 at 7:23 AM Ray Daniel Zimmerman <r...@cornell.edu> wrote: > 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> 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> > 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> 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 >> >> >> >
