Hi Dr.Zimmerman and Robert, I understand that Matpower can't work with an unbalanced three phase circuit. For this example, I'm only working with the A phase leg of the circuit. I'm just not sure how to setup the connection between nodes correctly.
Thank you Thai On Jun 19, 2015 4:48 AM, "Robert Spiewak" <[email protected]> wrote: > Thai, > > You cannot aproximate unbalanced system consited of branches and loads > with 3W+N+G (three-phase, neutral and ground) via positive sequence solver > like MATPOWER. The principle of methodology (NR) assumes symmetry in the > system. Symmetry in branch impedances, loads and generation sources. > > Best Regards, > > Robert Spiewak > > > On Jun 19, 2015, at 08:18, Ray Zimmerman <[email protected]> wrote: > > > > MATPOWER does not model unbalanced 3-phase systems, and without a lot of > work to refresh my memory, I’m not comfortable commenting on the > possibility of a good single-phase approximation in your case. > > > > Maybe someone else can comment. > > > > Ray > > > > > > > >> On Jun 18, 2015, at 8:24 PM, Thai Tran <[email protected]> wrote: > >> > >> Hi Dr.Zimmerman, > >> > >> I'm new to matpower so please excuse me if this is a silly question. > >> > >> I'm trying to use matpower to calculate power flow for a distribution > grid. This circuit has power coming from a substation on 12.47 kV three > phase line. Single phase transformers tap off the three phase line and step > the voltage down to 120V to serve houses in the circuit. In matpower, > transformers are modeled as a branch, how should I model the connections in > my circuit? > >> > >> For example: > >> substation is connected to transformer 1 which is then connected to 5 > loads. In the circuit model it would be > >> substation -> transformer > >> transformer -> load 1 > >> ... > >> transformer -> load 5 > >> > >> Should I model this in the branch matrix as > >> > >> substation(node 1) -> load 1 (node 2) > >> ... > >> substation(node 1) -> load 5 (node 6) > >> load 1(node 2) -> load 2 (node 3) > >> ... > >> etc. > >> > >> > >> Also since the transformer step the voltage level from 12.47kV to 120V, > which level should I use to calculate my p.u impedance? > >> Thank you > >> Thai > > > > > > > > > > >
