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Three-Phase Transformer (Two Windings)

Implement a three-phase transformer with configurable winding connections

Library

Elements

Description

The Three-Phase Transformer (Two Windings) block implements a three-phase transformer using three single-phase transformers. You can simulate the saturable core or not simply by setting the appropriate check box in the parameter menu of the block. See the Linear Transformer block and Saturable Transformer block sections for a detailed description of the electrical model of single-phase transformers.

The two windings of the transformer can be connected in the following manner:

The block takes into account the connection type you have selected, and the icon of the block is automatically updated. An input port labeled N is added to the block if you select the Y connection with accessible neutral for winding 1. If you ask for an accessible neutral on winding 2, an extra outport port labeled n is generated.

The following icons are displayed for four arbitrary settings

The saturation characteristic, when activated, is the same as the one described for the Saturable Transformer block, and the icon of the block is automatically updated. If the fluxes are not specified, the initial values are automatically adjusted so that the simulation starts in steady state.

The leakage inductance and resistance of each winding are given in p.u. based on the transformer nominal power Pn and on the nominal voltage of the winding (V1 or V2). Refer to the per unit explanations given in the Linear Transformer and Saturable Transformer blocks reference sections.

Dialog Box and Parameters

Nominal power and frequency
The nominal power rating, in volt amperes (VA), and nominal frequency, in hertz (Hz), of the transformer.
Winding 1 (ABC) connection
The phase connection for winding 1.
Winding parameters
The phase-to-phase nominal voltage in volts rms, resistance, and leakage inductance in p.u. for winding 1.
Winding 2 (abc) connection
The phase connection for winding 2.
Winding parameters
The phase-to-phase nominal voltage in volts rms, resistance, and leakage inductance in p.u. for winding 2.
Saturable core
If selected, implements a saturable three-phase transformer.
Magnetization resistance Rm
The magnetization resistance Rm, in p.u.
Magnetization reactance Lm
The magnetization inductance Lm, in p.u., for a nonsaturable core. The Magnetization reactance Lm parameter is not visible in the dialog box if the Saturable core parameter is selected.
Saturation characteristic
The saturation characteristic for the saturable core. Specify a series of current/ flux pairs (in p.u.) starting with the pair (0,0). This parameter is visible only if the Saturable core parameter is selected.
Specify initial fluxes
If selected, the initial fluxes are defined by the [phi0A phi0B phi0C] parameter.
[phi0A, phi0B, phi0C]
Specifies initial fluxes for each phase of the transformer. This parameter is visible only if the Specify initial fluxes and Saturable core parameters are selected.
Measurements
Select Winding voltages to measure the voltage across the winding terminals of the Three-Phase Transformer block.
Select Winding currents to measure the current flowing through the windings of the Three-Phase Transformer block.
Select Fluxes and magnetization currents to measure the flux linkage, in volt seconds (V.s), and the magnetization current (for saturable transformers only).
Select All measurement (V, I, Flux) to measure the winding voltages, currents, magnetization currents, and the fluxes.
Place a Multimeter block in your model to display the selected measurements during the simulation. In the Available Measurements list box of the Multimeter block, the measurements are identified by a label followed by the block name.
If the Winding 1 ABC connection parameter is set to Y, Yn, or Yg, the labels are as follows.

Measurement
 Label
Winding voltages
 Uan_w1:, Ubn_w1:, Ucn_w1:
or:
Uag_w1:, Ubg_w1:, Ucg_w1:
Winding currents
 Ian_w1:, Ibn_w1:, Icn_w1:
or:
Iag_w1:, Ibg_w1:, Icg_w1:
Fluxes
 Flux_A:, Flux_B:, Flux_C:
Magnetization currents
 Imag_A:, Imag_B:, Imag_C:
If the Winding 1 ABC connection parameter is set to Delta (D11) or Delta (D1), the labels are as follows.

Measurement
 Label
Winding voltages
 Uab_w1:, Ubc_w1:, Uca_w1:
Winding currents
 Iab_w1:, Ibc_w1:, Ica_w1:
Fluxes
 Flux_A:, Flux_B:, Flux_C:
Magnetization currents
 Imag_A:, Imag_B:, Imag_C:

The same labels apply for the Winding 2 (abc) connection parameter, except that 1 is replaced by 2 in the labels.

Example

The psbtransfo3ph.mdl circuit is using the Three-Phase Transformer block where the saturable core is simulated. Both windings are connected in a Y grounded configuration. Note that the neutral points of the two windings are internally connected to the ground.

Run the simulation and observe the simulation results.

See Also
Three-Phase Transformer (Three Windings)


  Three Level Bridge Three-Phase Transformer (Three Windings)