Power System Blockset    
Three-Phase Transformer (Three Windings)

Implement a three-phase transformer with configurable phase connection.

Library

Elements

Description

This block implements a three-phase transformer by using three single-phase transformers with three windings. The saturable core can be simulated or not, simply by setting the appropriate checkbox in the parameter menu of the block. See the Linear transformer and Saturable transformer sections for a detailed description of the electrical model of single-phase transformers.

The three windings of the transformer can be connected in the following manner.

The block take into count 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 wye connection with accessible neutral for the winding 1. If you ask for an accessible neutral on winding 3, an extra outport port labeled n3 is generated.

The following icons are displayed for three 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 will be automatically adjusted so that the simulation starts in steady state.

The leakage inductances and resistance of each winding is given in p.u. based on the transformer nominal power Pn and on the nominal voltage of the winding (V1, V2 or V3). Refer to the per unit explanations given in the Linear Transformer and Saturable Transformer blocks reference sections.

Dialog Box and Parameters

Port configuration
Specify the ABC port of winding one as input terminals or as output terminals. The terminals of the winding two and three will then be reconfigured consequently.
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 the winding 1.
Winding parameters
The phase-to-phase nominal voltage in volts rms, resistance, and leakage inductance in p.u. for the winding 1.
Winding 2 (abc2) connection
The phase connection for the winding 2.
Winding parameters
The phase-to-phase nominal voltage in volts rms, resistance, and leakage inductance in p.u. for the winding 2.
Winding 3 (abc3) connection
The phase connection for the winding 3.
Winding parameters
The phase-to-phase nominal voltage in volts rms, resistance, and leakage inductance in p.u. for the winding 3.
Saturable core
if checked, 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 checked.
Saturation characteristic
The saturation characteristic for the saturable core. Specify a serie of current/ flux pairs (in p.u.) starting with the pair (0,0). This parameter is visible only if the Saturable core parameter is checked.
Specify initial fluxes
if checked, the initial fluxes are defined by the [phi0A, phi0B, phi0C] parameter
[phi0A, phi0B, phi0C] (pu):
Specifies initial fluxes for each phase of the transformer. This parameter is visible only if the Specify initial fluxes and Saturable core parameters are checked.
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 winding voltages, currents, magnetization currents, and the fluxes.
Select All measurements (V, I, Flux) to measure the winding voltages, winding currents, magnetization currents, and fluxes.
Place a Multimeter block in your model to display the selected measurements during the simulation. In the Available Measurement listbox of the Multimeter block, the measurements will be 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 will be 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 will be 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 (abc2) connection and Winding 3 (abc3) connection parameters, except that the 1 is replaced by 2 or by 3 in the labels.

Example

The psbtransfo3wdn.mdl circuit is using two Three-Phase Transformer blocks. In this example the ABC terminals of winding one of T1 transformer are configured as inputs and the ABC terminals of winding one of T2 transformer are set configured as outputs.

See Also
Three-Phase Transformer (Two Windings)


 Three-Phase Transformer (Two Windings) Thyristor