On May 1, 2013, at 3:31 PM, Mirko Todorovski wrote:
> Dear all,
> I would like to test Newton’s method performance under flat start conditions
> using test systems from MATPOWER. The experiments were done using case3012wp
> in the following way:
> 1. I removed the comment on line 199 in runpf and put comments on lines 200
> and 201, therefore the initial state is calculated as V0 = ones(size(bus, 1),
> 1); i.e. the flat start is applied. When I execute the command
> runpf('case3012wp',mpoption,'r1.txt') for minimum and maximum voltage
> magnitude and angle I get the following:
> Minimum Maximum
> ------------------------- --------------------------------
> Voltage Magnitude 0.880 p.u. @ bus 2445 1.044 p.u. @ bus 926
> Voltage Angle -53.54 deg @ bus 2733 1.38 deg @ bus 310
> which is a correct solution.
>
> 2. I put back the comment on line 199 and remove comments on lines 200 and
> 201 in runpf and execute the following commands:
> define_constants;
> mpc = loadcase('case3012wp');
> mpc.bus(:,VM) = 1;
> mpc.bus(:,VA) = 0;
> runpf(mpc,mpoption,'r2.txt');
> I got the message that Newton’s power flow did not converge.
Note that the initial guess for generator bus voltages is calculated based on
the voltage set points from mpc.gen ( line 201):
V0(gbus) = gen(on, VG) ./ abs(V0(gbus)).* V0(gbus);
^^^^^^^^^
Thus for the code you have in (2), V = 1.0 for the pq buses but it is ~= 1.0
for ref and pv buses.
The following code will produce the intended flat start initial guess.
define_constants;
mpc = loadcase('case3012wp');
mpc.bus(:,VM) = 1;
mpc.bus(:,VA) = 0;
mpc.gen(:,VG) = 1.0;
runpf(mpc,mpoption,'r2.txt');
Shri
>
> Shouldn’t these two approaches give the same results?
>
> Best regards,
> Mirko Todorovski
>
