Using NERC Flowgates for Transfer Limit Analysis -Troubleshooting
I received some very unusual
TDF factors for Hydro-Quebec control area when I tried to create
TDF factors for my load flow case. What’s wrong?
It is likely the problem is due
to the fact that your load flow case has several swing buses,
which are connected only through DC lines. PSS™MUST does
not allow transferring power over DC ties. When using a MMWG type
load flow case, it is a problem for HQ, MH, and WSCC equivalent
buses.
A simple fix to this problem is
to use PSS™E to shutdown all buses not AC connected to the
main swing bus. A quick way to do this, is to change the type
of ‘secondary’ swing buses to the type two (from type
3) and then use PSS™E activity TREE to shutdown created
islands. You can use PSS™MUST to list all swing buses.
I tried to use the NERC IDC seasonal
case and had a few problems with PSS™E and PSS™MUST.
Sometimes it doesn't converge at all, but even it does converge,
results (monitored element flows) are at least somewhat suspicious?
What’s wrong?
IDC cases are developed to calculate
IDC factors only, not for actual load flow studies. There is no
warranty that these load flow cases have reasonable load forecasts,
… and actual flows are not valid. IDC cases contain good
estimates of the US Eastern Interconnection topology and generator
statuses. When using NERC IDC cases within PSS™MUST you
should use the DC load flow solution options for solving initial
load flow as it always converges. You SHOULD NOT use these
load flow cases to perform a transfer limit analysis.
