3/5 Limb UMEC Transformer

This component models a 3-phase, 3/5 limb 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 Core Construction	Choice		Select 3-phase Bank, 3-Limb or 5-Limb core configuration

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

Primary Voltage (Line-to-Line RMS)	REAL	Constant	The voltage rating of the primary winding [kV]

Secondary Voltage (Line-to-Line RMS)	REAL	Constant	The voltage rating of the secondary winding [kV]

Winding # Type	Choice		Select the connection type for the specified winding # - Star (Y) or Delta (D) connected

Delta Lags or Leads Y	Choice		Select whether the D-connected winding voltage will lead or lag the Y-connected winding voltage by 30°

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

Leakage Reactance	REAL	Constant	The total leakage reactance of transformer. This can be calculated based on short-circuit test results [pu]

No Load Losses	REAL	Literal	The total no-load core losses of the transformer. Winding losses are not to be included here [pu]

Copper Losses	REAL	Literal	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]

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 3-phase view or single-line view

Display Details?	Choice		Select Yes or No. This input is only functional in Single Line View and will display MVA and winding voltages near the component

Tap Setting

REAL

Constant

Select the tap setting. This parameter cannot be adjusted during the run

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]

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

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

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

Name for Phase Current (+in,kA)

REAL

Output

Name for the specified phase line current. This is both the line and the phase current if winding is Y-connected, and line current only if winding is delta connected. This parameter is positive into the winding from the line [kA]

Name for Phase -> Phase Winding Current (kA)

REAL

Output

Name for the specified phase to phase current [kA]

Winding # Flux (Phase)	REAL	Output	Enter a name to monitor flux in the specified winding of the selected phase [pu]

Winding # Leakage Flux (Phase)	REAL	Output	Enter a name to monitor leakage flux in the specified winding of the selected phase [pu]

Yoke Flux (Phase)	REAL	Output	Enter a name to monitor the yoke flux in the selected phase [pu]

NOTE: If no name is specified, these output signals will not be monitored.

Winding # Flux (Phase)	REAL	Output	Enter a name to monitor flux in the specified winding in the selected phase [pu]

Winding # Leakage Flux (Phase)	REAL	Output	Enter a name to monitor leakage flux in the specified winding in the selected phase [pu]

Yoke Flux (Phase)	REAL	Output	Enter a name to monitor the yoke flux in the selected phase [pu]

Zero-Sequence Flux (Phase)	REAL	Output	Enter a name to monitor the zero-sequence flux in the selected phase [pu]

NOTE: If no name is specified, these output signals will not be monitored.

Winding # Flux (Phase)	REAL	Output	Enter a name to monitor flux in the specified winding in the selected phase [pu]

Winding # Leakage Flux (Phase)	REAL	Output	Enter a name to monitor leakage flux in the specified winding in the selected phase [pu]

Yoke Flux (Phase)	REAL	Output	Enter a name to monitor the yoke flux in the selected phase [pu]

Outer-Limb Flux (Phase)	REAL	Output	Enter a name to monitor the outer-limb flux in the selected phase [pu]

Zero-Sequence Flux (Phase)	REAL	Output	Enter a name to monitor the zero-sequence flux in the selected phase [pu]

3/5 Limb UMEC Transformer

Description

Input Parameters