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Hello everyone,

I am performing a renewable impact study, and as part of this study, we must simulate faults somewhat close-in to the proposed wind farm. The wind farm uses the following WECC generic models, and we're observing numerical instability (network non-convergence) when the fault is applied for the entire duration of the fault, even when significant fault impedance is added:

REGCA1 REECA1 WTDTA1 WTPTA1 WTARA1 REPCTA1 WTTQA1

The faults we are simulating do not completely isolate the wind farm from the rest of the network (and the traditional generators in it). Despite this, we are having the network non-convergence issues. We've tried several approaches to fix this problem but nothing seems to work. These include:

• Switching to the REGC_B (REGCBU1 in PSS/E) model, which supposedly has better numerical stability under weak grid conditions
• Changing XSORCE of the wind machines... Tried 9999, 0.9, 0.05, none of these achieve convergence
• Adding fault impedance. However, so much fault impedance has to be added that the faulted bus only drops in some cases to 0.45 p.u. voltage.

Does anyone have experience with diagnosing network non-convergence/numerical instability issues with the 2nd generation generic renewable models? I'm sure there's a way to achieve convergence with these models, and to truly simulate a "bolted" fault, but we haven't found a good solution so far.

Thanks for any and all help.

Hello everyone,

I am performing a renewable impact study, and as part of this study, we must simulate faults somewhat close-in to nearby the proposed wind farm. The wind farm uses the following WECC generic models, and we're observing numerical instability (network non-convergence) when the fault is applied for the entire duration of the fault, even when significant fault impedance is added:

REGCA1 REECA1 WTDTA1 WTPTA1 WTARA1 REPCTA1 WTTQA1

The faults we are simulating do not completely isolate the wind farm from the rest of the network (and the traditional generators in it). network. Despite this, we are having the network non-convergence issues. We've tried several approaches to fix this problem but nothing seems to work. These include:

• Switching to the REGC_B (REGCBU1 in PSS/E) model, which supposedly has better numerical stability under weak grid conditions
• Changing XSORCE of the wind machines... Tried 9999, 0.9, 0.05, none of these achieve convergence
• Adding fault impedance. However, so much fault impedance has to be added that the faulted bus only drops in some cases to 0.45 p.u. voltage.

Does anyone have experience with diagnosing network non-convergence/numerical instability issues with the 2nd generation generic renewable models? I'm sure there's a way to achieve convergence with these models, and to truly simulate a "bolted" fault, fault near (one or two buses away from) the new wind facility, but we haven't found a good solution so far.

Thanks for any and all help.