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Hi I am writing this based on my experience. To solve a case ( or converge a blown up case) , you need to do following:

STEP1. You need to relax the solution parameters to following values. Using default values for solving a case might blow it up. Set solution parameters to following values:

i. Blow-up parameters to a large number (typical range is 90000 to 99999)

ii. TOLN (largest mismatch in MW and MVARs) to 1.1.

iii. VCTOLQ (controlled bus Q mismatch convergence tolerance) to 10.1

iv. VCTOLV (controlled bus voltage error convergence tolerance) to 10.00001

STEP2. I would suggest following selections for solving-use the “Fixed slope decoupled Newton-Raphson” method as this method performs better that other algorithms for difficult cases. (Full Newton or Decoupled). Enable FLAT start, Disable all other parameters, as shown below:

STEP3. Disconnect buses that have large angle changes that cause the solution to diverge. These buses might show up in the column DELTA/V/ column ( Highlighted) NOTE THESE BUS NUMBERS, AS YOU NEED TO RECONNECT THEM LATER.

STEP4. Now gradually enable the parameters. My personal experience says following this sequence:

i. VAR limits first, then Adjust DC taps, then TAP (stepping) then Adjust phase shifters, then Switch shunts ( Enable all) ii. For very difficult case, the case might blow up if you enable any option mentioned above (including the FLAT start). In that case disconnect the buses mentioned in step 3

iii. Lock any switched shunts that toggle while solving. iv. Turn generators on or off if:

• Bus voltages are too high (≥1.2) or too low (≤0.7) for the case to converge • There is not enough reactive support for the case to converge. STEP5. Once you reach a solved case, you need to reconnect the buses which you disconnected while solving. Make sure that you manually match the voltage and angle of the disconnected bus to the voltage and angle of the Bus it is connected. After you have reconnected all the buses, GRADUALLY put the solution parameters to back to the default values.
i. Blow-up = 5.0 ii. TOLN =0.1 iii. VCTOLQ = to 0.1 iv. VCTOLV = to 0.00001

I wasn’t able to able to upload pics because of some restrictions imposed by this site. I hope this helps though Nihal

Hi I am writing this based on my experience. To solve a case ( or converge a blown up case) , you need to do following:

STEP1. You need to relax the solution parameters to following values. Using default values for solving a case might blow it up. Set solution parameters to following values:

i. Blow-up parameters to a large number (typical range is 90000 to 99999)

ii. TOLN (largest mismatch in MW and MVARs) to 1.1.

iii. VCTOLQ (controlled bus Q mismatch convergence tolerance) to 10.1

iv. VCTOLV (controlled bus voltage error convergence tolerance) to 10.00001

STEP2. I would suggest following selections for solving-use the “Fixed slope decoupled Newton-Raphson” method as this method performs better that other algorithms for difficult cases. (Full Newton or Decoupled). Enable FLAT start, Disable all other parameters, as shown below:

STEP3. Disconnect buses that have large angle changes that cause the solution to diverge. These buses might show up in the column DELTA/V/ column ( Highlighted) NOTE THESE BUS NUMBERS, AS YOU NEED TO RECONNECT THEM LATER.

STEP4. Now gradually enable the parameters. My personal experience says following this sequence:

i. VAR limits first, then Adjust DC taps, then TAP (stepping) then Adjust phase shifters, then Switch shunts ( Enable all) all)

ii. For very difficult case, the case might blow up if you enable any option mentioned above (including the FLAT start). In that case disconnect the buses mentioned in step 33'

iii. Lock any switched shunts that toggle while solving. solving.

iv. Turn generators on or off if:

• Bus voltages are too high (≥1.2) or too low (≤0.7) for the case to converge converge

• There is not enough reactive support for the case to converge. converge.

STEP5. Once you reach a solved case, you need to reconnect the buses which you disconnected while solving. Make sure that you manually match the voltage and angle of the disconnected bus to the voltage and angle of the Bus it is connected. After you have reconnected all the buses, GRADUALLY put the solution parameters to back to the default values.
i. Blow-up = 5.0 ii. TOLN =0.1 iii. VCTOLQ = to 0.1 iv. VCTOLV = to 0.00001

I wasn’t able to able to upload pics because of some restrictions imposed by this site. I hope this helps though Nihal