This component models a single-phase auto transformer and is based on the classical modeling approach.
Options are provided so that the user may choose between either a magnetizing branch (linear core), or a current injection routine to model magnetizing characteristics. If desired, the magnetizing branch can be eliminated altogether, leaving the transformer in 'ideal' mode, where all that remains is a series leakage reactance.
This component also includes an on-load tap changing capability.
More: |
Name for Identification |
Text |
Optional text parameter for identification of the component. |
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Transformer MVA |
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REAL |
Constant |
The apparent power rating of the transformer [MVA] |
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Base Operation Frequency |
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REAL |
Constant |
The base frequency of the electrical system, in which the transformer resides [Hz] |
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Leakage Reactance |
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REAL |
Constant |
The total leakage reactance of transformer. This can be calculated based on short-circuit test results [pu] |
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No Load Losses |
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REAL |
Constant |
The total no-load core losses of the transformer. Winding losses are not to be included in value [pu] |
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Copper Losses |
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REAL |
Constant |
Enter the total copper losses for the transformer. Equivalent winding resistances are calculated based on this entry so that losses are distributed evenly among all the windings. These resistances are then placed in series with the windings [pu] |
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Ideal Transformer Model |
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Choice |
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Select Yes or No. This input must be Yes when modeling core saturation
NOTE: 'Ideal' transformer should not be confused with an ideal ratio changer. 'Ideal' here simply means that the magnetizing branch has been eliminated (leakage reactance is still present as well) |
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On Load Tap Changer |
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Choice |
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Select Yes or No. Selecting Yes will enable the on-load tap changer, which requires an external signal input (see On-Load Tap Changer). |
Winding Voltage RatingsWinding Voltage Ratings
Winding Voltage (RMS) |
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REAL |
Constant |
The RMS voltage rating of the corresponding winding [kV] |
NOTE: See Adjusting Saturation Properties for more details on these inputs
Saturation Enabled |
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Choice |
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Select Yes or No to enable or disable the core saturation routine
NOTE: Always set the transformer to 'ideal' when enabling saturation. Otherwise, both the magnetizing branch and the saturation routine will both be used. |
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Air Core Reactance |
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REAL |
Constant |
Usually approximately twice the leakage reactance [pu] |
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Inrush Decay Time Constant |
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REAL |
Constant |
The decay time for the transformer inrush current [s] |
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Knee Voltage |
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REAL |
Constant |
The knee point voltage corresponding to the knee point of the saturation curve [pu] |
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Time to Release Flux Clipping |
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REAL |
Constant |
Time interval from start-up in which the model will 'clip' (limit) the calculated flux linkage values. This is simply a modeling 'trick' to prevent instability at start-up [s] |
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Magnetizing Current |
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REAL |
Constant |
The percentage of primary winding current that flows through the transformer magnetizing susceptance. This value can be calculated based on the open-circuit test results. The magnetizing susceptance is calculated based on this value [%] |
Monitoring of Currents and FluxMonitoring of Currents and Flux
Name for Winding Current |
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REAL |
Output |
Name for the specified winding current [kA] |
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Name for LV Side Current |
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REAL |
Output |
Name for the low voltage side current [kA] |
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Name for Magnetizing Current (pu) |
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REAL |
Output |
Name for the magnetizing current [pu] |
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Name for Flux Linkage (pu) |
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REAL |
Output |
Name for the calculated flux linkage [pu] |