Dear Shri,
Thank you for your answer, but I think that adding mpc.gen(:,VG) = 1.0; changes the generator set voltages so different case is obtained, which happens to be solvable by Newton’s method. I would like to keep generator set voltages as they are in case3012wp and solve it with a flat start. I have noticed that this is a problem only in case3012wp and case2737sop. In all other MATPOWER cases the procedure (2) works fine (with line 199 commented and lines 200 and 201 uncommented in runpf). Best regards, Mirko Todorovski From: [email protected] [mailto:[email protected]] On Behalf Of Shri Sent: Wednesday, May 01, 2013 11:19 PM To: MATPOWER discussion forum Cc: [email protected] Subject: Re: Flat start 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
