This component models a 1-phase, 2-winding 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. A magnetic hysteresis model is also available in this 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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Eddy Current Losses |
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REAL |
Constant |
The eddy current portion of the no-load core losses, based on transformer rating. Hysteresis losses may also be added here if hysteresis is not modeled. Winding losses are not to be included in this 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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Tap Changer on Winding |
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Choice |
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Select None, #1 or #2.
Select the winding number on which to place the on-line tap changer (or none).
See On-Line Tap Changer for more details. |
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Graphics Display |
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Choice |
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Select Windings or Circles. |
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Winding # Voltage (RMS) |
REAL |
Constant |
The RMS voltage rating of the corresponding winding # [kV]. |
NOTE: See Adjusting Saturation Properties and Transformer Magnetic Hysteresis 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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Place Saturation on Winding |
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Choice |
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Select Middle, Winding #1, or #2.
Middle is the preferred option, whereas specifying the actual winding number is left in for legacy support. Selecting the winding number will place the saturation current injection directly on that winding. Note that this can cause ideal loop problems when performing certain types of studies (such as black start).
See Adjusting Saturation Properties for more details. |
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Hysteresis |
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Choice |
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Select None, Basic Model, or Jiles-Atherton.
The Basic Model models hysteresis based a translation on the transformer l-I characteristic, whereas the Jiles-Atherton model involves a conversion from an M-H loop to a B-H loop characteristic.
See Transformer Magnetic Hysteresis for more details. |
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Inrush Decay Time Constant |
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REAL |
Constant |
The decay time for the transformer inrush current [s].
This option is enabled only when Hysteresis | None is selected. |
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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].
This option is enabled only when Hysteresis | None is selected. |
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Air Core Reactance |
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REAL |
Constant |
Usually approximately twice the leakage reactance [pu]. |
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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 [%]. |
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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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Remanent Flux |
REAL |
Constant |
Enter
the remanent flux as a per-unit value of the peak flux at
rated voltage [pu].
This option is enabled only when Hysteresis | Basic Model or Hysteresis | Jiles-Atherton is selected. |
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Loop Width |
REAL |
Constant |
Enter
the loop width as a percentage of the Magnetizing
Current
[%].
This option is enabled only when Hysteresis | Basic Model is selected. |
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Nominal Flux Density (T) |
REAL |
Constant |
Enter
the nominal flux density corresponding to the saturation curve
[T].
This option is enabled only when Hysteresis | Jiles-Atherton is selected. |
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Magnetic Material |
Choice |
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Select
Custom,
or Default.
This option is enabled only when Hysteresis | Basic Model is selected. |
Magnetic Characteristics of the Material
NOTE: This category is enabled only if Hysteresis | Jiles-Atherton and Magnetic Material | Custom is selected.
Domain Flexing Parameter |
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REAL |
Constant |
This parameter represents the contribution of reversible magnetization process. |
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Domain Pinning Parameter |
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REAL |
Constant |
This parameter has a direct impact on the width of the loop [A/m]. |
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Parameter to Adjust K with M |
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REAL |
Constant |
This parameter adjusts the domain pinning parameter with magnetization for better representation of the shoulder area. |
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Inter-Domain Coupling |
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REAL |
Constant |
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Saturated Anhysteretic Magnetization |
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REAL |
Constant |
[A/m]. |
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Coefficient # of Anysteretic Curve |
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REAL |
Constant |
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Name for Magnetizing Current [kA] |
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REAL |
Output |
Name for the magnetizing current [kA]. |
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Name for Flux Linkage [kWb-N] |
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REAL |
Output |
Name for the calculated flux linkage [kWb-N]. |
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Name for Magnetic Field Intensity |
REAL |
Output |
Name for the magnetic field intensity.
This output is enabled only when Hysteresis | Jiles-Atherton and Saturation Enabled | Yes is selected. |
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Name for Flux Density [T] |
REAL |
Output |
Name for the flux density [T]. |
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Name for Winding # Current |
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REAL |
Output |
Name for the specified winding current [kA]. |