Re: infinite bus, 1 branch/1 gen

[Carlos E Murillo-Sanchez]

Russ Patterson wrote: Hi Carlos,   Thank you.  That makes sense.  Based on that, I would expect to be able to set the bus voltage, Vm, and it stick, but it doesn’t.  If I set Vm=2 and run the load flow it solves properly with the resulting bus voltage being 1.154pu.   So, in essence, I am specifying the magnitude for the slack bus in the “mpc.gen Vg” setting, and then I am specifying the angle for the slack bus in the “mpc.bus Va” setting.  You would expect both mag and angle to be specified in the same place.   This is counterintuitive, which is why I ask if this level of detail about how input is used/overridden is documented anywhere – or if it will just be a learn-by-trying approach.   Either way, I’m very happy to have found this fantastic software.  Thank you for your help.   Best regards, Russ Dear Russ: You are right;  the data structure for MATPOWER was originally chosen to resemble what where then popular industry formats for power flow, with the corresponding outstanding assumptions about what is input data and what is output data in the power flow problem.  When using this data for other problems (such as optimal power flow), it becomes even less clear if you haven't been a long-time follower of the development of those data formats.  For example, for power flow the generator voltages are input from the VG column of the gen() matrix as you discovered. But for optimal power flow, the bus voltage limits (which then the generators must also respect) are specified in columns VMAX and VMIN in the bus() matrix. Carlos.