A: OneLiner CIR model is a functional model that can produce fault current with both positive and negative sequence components. It injects a positive sequence reactive current based on the magnitude of (1.0 - V1), the positive sequence slope setting, and the power-factor angle (target is -90 for V1 < 1 and +90 for V1 > 1), where V1 is the positive sequence voltage of the CIR terminal bus.
At the same time, the CIR model injects a negative sequence current based on the magnitude of V2 and the negative sequence slope setting at an angle 90 degrees ahead of the V2 phasor, where V2 is the negative sequence voltage at the CIR terminal bus.
The magnitude of the positive sequence reactive current is limited to the current limit specified by the user (e.g., 1.2 times full load current). The magnitude of the negative sequence current is limited to the full load current. The PF angle targets of the CIR model cannot be changed.
The CIR current output is based on the following:
I1pu = (1 - V1pu) * k1
and
I2pu = V2pu * k2
where:
I1pu = CIR positive sequence current magnitude in per unit on the generator base
V1pu = CIR terminal bus positive sequence voltage magnitude in per unit
k1 = CIR positive sequence slope setting
I2pu = CIR negative sequence current magnitude in per unit on the generator base
V2pu = CIR terminal bus negative sequence voltage magnitude in per unit
k2 = CIR negative sequence slope setting
For a positive sequence slope of 2.0, at CIR terminal bus voltage of 0.5pu should result in a CIR output 1pu positive sequence current.
Some additional important points about this model:
● The internal device topology and circuit physics are not simulated directly in OneLiner
● Simulation represents the post-transient period of IBR fault ride through based on functional requirements
● The model is grid-following, so it needs a reference from the grid
● Some scenarios make the +- 90 degree target PF unobtainable (e.g., 3LG fault near POI where circuit path between CIR and POI has non-zero resistance). There is an option in the Fault Simulation settings to allow the relaxation of the PF tolerance when that scenario is detected.
Additional details can be found in the OneLiner help section NEW | CONVERTER-INTERFACED RESOURCE COMMAND