Per-Unit Current vs. Saturation Factor (SF)
Per-Unit current vs. Per-Unit Voltage
This defines the saturation characteristics of the stator leakage reactance. There are two ways of entering the saturation data:
Here the saturation curve is specified as pairs of points (I, SF). The first point should be (0.0, 1.0) and the second point should be (I2, 1.0) where I2 is the current in per-unit at which the onset of saturation occurs. The remaining 8 points should be in pairs of per-unit current and their corresponding saturation factors. Thus, a maximum of 8 additional pairs of points can be specified. If less than 8 additional pairs are used the last pair must be (-1.0, -1.0) and all points thereafter are ignored. The points entered should have monotonically decreasing factors with monotonically increasing currents.
The second format is to specify the short-circuit test results in pairs of per-unit current and per-unit voltage (Ipu, Vpu). The first point should be (0.0, 0.0) and the second point should be (I2, V2), where I2 is the current in per unit at which the onset of saturation occurs and V2 is the corresponding pu voltage.
All I values will be internally re-scaled based on the actual current at the voltage V2 specified by the second point. The voltage must be in per-unit. If less than 10 points are available the last pair entered must be (-1.0, -1.0). The program in this case replaces the voltage with the saturation factor and re-scales the current to a per-unit value based on the unsaturated value of inductance input in the previous section. That is, the initial slope of the I-V curve should correspond to the stator and rotor unsaturated leakage reactances:
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Where,
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Initial slope of the I-V curve |
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Stator unsaturated leakage reactance |
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Rotor unsaturated leakage reactance |
The saturation factors are available as internal outputs.
