1-Phase 3-Winding UMEC Transformer

This component models a 1-phase, 3-winding transformer and is based on the UMEC modeling approach.

Options are provided so that the user may model the core saturation characteristic directly as an I-V curve. If desired, the magnetizing branch can be eliminated altogether, leaving the transformer in 'ideal' mode, where all that remains is a series leakage reactance. Some elements of core geometry (i.e. core type, yoke and winding limb dimensions, etc.) are required for data input as well.

Input Parameters

Transformer Name	Text		Just an identifier. A name should be entered here to avoid compilation warnings

Transformer MVA	REAL	Constant	The apparent power rating of the transformer [MVA]

Winding # Voltage (RMS)	REAL	Constant	The voltage rating of the primary winding [kV]

Base Operation Frequency	REAL	Constant	The base frequency of the electrical system, in which the transformer resides [Hz]

Leakage Reactance Winding #-#	REAL	Constant	The leakage reactance between the specified windings of the transformer. This can be calculated based on short-circuit test results [pu]

No Load Losses	REAL	Constant	Enter the open-circuit losses of the transformer [pu]

Copper Losses Winding #-#	REAL	Literal	Enter the copper losses between the specified windings of the transformer. These resistances are placed in series with the windings [pu] This can be calculated based on short-circuit test results [pu]

Model Saturation?	Choice		Select Yes or No to enable core saturation

Tap Changer on Winding	Choice		Select the winding number on which to place the on-line tap changer (or none)

Graphics Display	Choice		Select Windings or Circles

NOTE: The I-V characteristic defined by these inputs construct a piecewise linear saturation curve, where transitions between points are fully interpolated by PSCAD. If a 0.0 value is entered, PSCAD will ignore all points following the 0.0. This is useful in instances where the saturation curve has less then 10 points. The UMEC algorithm requires that the first quadrant of the saturation curve (with V in the vertical axis and I in the horizontal axis) to decrease in slope with each subsequent segment of the spline curve. Points that lead to slopes bigger that the previous registered slope will be ignored until a point leads to a smaller slope.

Magnetizing Current at Rated Voltage	REAL	Constant	The magnetizing current at rated voltage. This parameter is only used if core saturation is disabled [%]

Enable Saturation	REAL	Variable	Enter 0 to disable and 1 to enable core saturation

Point # – Current as a Percentage	REAL	Constant	Enter the I-coordinates of the I-V curve. These points can be non-zero if desired. The maximum number of points is 10 [%]

Point # – Voltage in pu	REAL	Constant	Enter the V-coordinates of the I-V curve. These points can be non-zero if desired. The maximum number of points is 10 [pu]

Winding # Flux	REAL	Output	Name for the flux in the specified core winding-limb [pu]

Winding # Leakage Flux	REAL	Output	Name for the leakage flux in the specified core winding-limb [pu]

Yoke Flux	REAL	Output	Name for the flux in the core yoke [pu]

Ratio Yoke/Winding-Limb Length	REAL	Constant	Enter the ratio of core yoke length to the core winding-limb length

Ratio Yoke/Winding-Limb Area	REAL	Constant	Enter the ratio of core yoke area to the core winding-limb area

1-Phase 3-Winding UMEC Transformer

Description

Input Parameters