Dear Dr Zimmerman

I have 2 questions.

First, in ac mode, if I want to calculate the branch power flow, take branch 1 
for example, should I use  sqrt( mpc.branch(1,PF)^2 + 
mpc.branch(1,QF)^2 ) ?    Or simply mpc.branch(1,PF) is the branch power flow 
we meant in the power system?

Second, the following is the PTDF matrix for the case14.m(a 14 bus example). I 
generate this use makePTDF(mpc.baseMVA,mpc.bus,mpc.branch,1). But I 
don't understand why line 14(branch 14) is all zero except column 7(bus 
7) . What does this mean. And if I increase bus 1's power load by 1 MW,  when I 
runopf(mpc), the power flow of branch 14, is not zero (I use  
sqrt( mpc.branch(1,PF)^2 + mpc.branch(1,QF)^2 ) ).


         0   -0.8380   -0.7465   -0.6675   -0.6106   -0.6291   -0.6573   
-0.6573   -0.6518   -0.6477
         0   -0.1620   -0.2535   -0.3325   -0.3894   -0.3709   -0.3427   
-0.3427   -0.3482   -0.3523
         0    0.0273   -0.5320   -0.1513   -0.1031   -0.1188   -0.1427   
-0.1427   -0.1380   -0.1346
         0    0.0572   -0.1434   -0.3167   -0.2158   -0.2487   -0.2986   
-0.2986   -0.2888  
 -0.2817
         0    0.0774   -0.0711   -0.1994   -0.2917   -0.2616   -0.2160   
-0.2160   -0.2249   -0.2314
         0    0.0273    0.4680   -0.1513   -0.1031   -0.1188   -0.1427   
-0.1427   -0.1380   -0.1346
         0    0.0799    0.3067    0.5026   -0.3012   -0.0389    0.3584    
0.3584    0.2808    0.2240
         0    0.0030    0.0113    0.0186   -0.0111   -0.2075   -0.6338  
 -0.6338   -0.4469   -0.4043
         0    0.0017    0.0066    0.0108   -0.0065   -0.1211   -0.1658   
-0.1658   -0.2608   -0.2360
         0   -0.0047   -0.0179   -0.0294    0.0176   -0.6714   -0.2004   
-0.2004   -0.2924   -0.3597
         0   -0.0028   -0.0108   -0.0177    0.0106    0.1979   -0.1207   
-0.1207   -0.1760   -0.2873
         0   -0.0004   -0.0016   -0.0026    0.0016    0.0291  
 -0.0177   -0.0177   -0.0259   -0.0161
         0   -0.0014   -0.0056   -0.0091    0.0055    0.1017   -0.0620   
-0.0620   -0.0904   -0.0563
        0        0         0         0         0         0         0   -1.0000  
       0         0
         0    0.0030    0.0113    0.0186   -0.0111   -0.2075    0.3662    
0.3662   -0.4469   -0.4043
         0    0.0028    0.0108    0.0177   -0.0106   -0.1979    0.1207    
0.1207    0.1760   -0.7127
         0    0.0019    0.0071    0.0117   -0.0070   -0.1307    0.0797    
0.0797    0.1163    0.0724
         0    0.0028   
 0.0108    0.0177   -0.0106   -0.1979    0.1207    0.1207    0.1760    0.2873
         0   -0.0004   -0.0016   -0.0026    0.0016    0.0291   -0.0177   
-0.0177   -0.0259   -0.0161
         0   -0.0019   -0.0071   -0.0117    0.0070    0.1307   -0.0797   
-0.0797   -0.1163   -0.0724

  Columns 11 through 14

   -0.6386   -0.6309   -0.6323   -0.6433
   -0.3614   -0.3691   -0.3677   -0.3567
   -0.1269   -0.1204   -0.1215   -0.1308
  
 -0.2655   -0.2519   -0.2543   -0.2738
   -0.2463   -0.2587   -0.2564   -0.2387
   -0.1269   -0.1204   -0.1215   -0.1308
    0.0948   -0.0137    0.0061    0.1607
   -0.3076   -0.2264   -0.2412   -0.3569
   -0.1795   -0.1321   -0.1408   -0.2083
   -0.5128   -0.6415   -0.6181   -0.4348
   -0.5402    0.1683    0.1452   -0.0356
    0.0061   -0.5211   -0.1697   -0.0887
    0.0213   -0.2886   -0.5936   -0.3104
         0         0         0         0
   -0.3076   -0.2264   -0.2412   -0.3569
   -0.4598   -0.1683   -0.1452    0.0356
   -0.0274   -0.1902   -0.2367   -0.6008
   -0.4598   -0.1683   -0.1452    0.0356
    0.0061    0.4789   -0.1697   -0.0887
    0.0274    0.1902    0.2367   -0.3992


Thank you very much for your patience.

Sincerely,

Yahook

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