The TAP column of the transformer entry in the branch matrix should be 1.0 (not
7.5) to indicate the nominal turns ratio. The 7.5 is already indicated by the
ratio of the BASE_KV for the two buses (150 kV/20 kV).
Ray
> On Nov 27, 2017, at 5:53 AM, Simona Ruggeri <[email protected]>
> wrote:
>
> Dear all,
>
> I am a new user of Matpower and I'm trying to perform a power flow
> calculation on a simple MV passive network, characterized by a primary
> substation (with its own 150/20 transformer), 6 nodes and 5 branches.
> If I do not consider the transformer, as you can see in the following lines,
> the PF converges.
>
> mpc.baseMVA 100
>
> mpc.bus[
> 1 3 0 0 0 0 1 1 0 20
> 1 1,05 0,95
> 2 1 0,4847 0,235 0 0 1 1 0 20
> 1 1,05 0,95
> 3 1 0,130 0,063 0 0 1 1 0 20
> 1 1,05 0,95
> 4 1 0,0505 0,0245 0 0 1 1 0 20
> 1 1,05 0,95
> 5 1 0,0315 0,0155 0 0 1 1 0 20
> 1 1,05 0,95
> 6 1 0,0505 0,0245 0 0 1 1 0 20
> 1 1,05 0,95
> ]
>
> mpc.branch[
> 1 4 0,253 0,2762 2,0e-06 0 0 0 0T 0
> 1 -360 360
> 4 6 0,134 0,1469 1,0e-06 0 0 0 0 0
> 1 -360 360
> 6 5 1,183 1,2893 9,4e-06 0 0 0 0 0
> 1 -360 360
> 5 2 0,264 0,2882 2,1e-06 0 0 0 0 0
> 1 -360 360
> 2 3 0,098 0,0735 5,3e-07 0 0 0 0 0
> 1 -360 360
> ]
>
> mpc.gen[
> 1 0 0 0 0 1 100 1 25 0
> 0 0 0 0 0 0 0 0 0 0
> 0
> ]
>
> On the contrary, if I consider the transformer, the PF does not converge.
>
> mpc.bus[
> 1 3 0 0 0 0 1 1 0 150
> 1 1,05 0,95
> 7 1 0 0 0 0 1 1 0 20
> 1 1,05 0,95
> 2 1 0,4847 0,235 0 0 1 1 0 20
> 1 1,05 0,95
> 3 1 0,130 0,063 0 0 1 1 0 20
> 1 1,05 0,95
> 4 1 0,0505 0,0245 0 0 1 1 0 20
> 1 1,05 0,95
> 5 1 0,0315 0,0155 0 0 1 1 0 20
> 1 1,05 0,95
> 6 1 0,0505 0,0245 0 0 1 1 0 20
> 1 1,05 0,95
> ]
>
> mpc.branch[
> 1 7 0,018 0,4800 0 0 0 0 7.5 0
> 1 -360 360
> 7 4 0,253 0,2762 2,0e-06 0 0 0 0 0
> 1 -360 360
> 4 6 0,134 0,1469 1,0e-06 0 0 0 0 0
> 1 -360 360
> 6 5 1,183 1,2893 9,4e-06 0 0 0 0 0
> 1 -360 360
> 5 2 0,264 0,2882 2,1e-06 0 0 0 0 0
> 1 -360 360
> 2 3 0,098 0,0735 5,3e-07 0 0 0 0 0
> 1 -360 360
> ]
>
> mpc.gen[
> 1 0 0 0 0 1 100 1 25 0
> 0 0 0 0 0 0 0 0 0 0
> 0
> ]
>
> I think that the problem is the way I model the transformer or the nodes
> where it is connected.
> Thank you in advance for your help.
>
> Simona
