Documentation

Wye-Delta11 Transformer

Linear nonideal wye-delta11 transformer with three-limb core

Library

Passive Devices / Transformers

Description

The Wye-Delta11 Transformer block models a linear, nonideal transformer with a three-limb core, in which the primary windings are configured in a wye connection and the secondary windings are configured in a delta connection. The delta voltages lead the wye voltages by 30 degrees, hence the name 11 o’clock delta. The block includes linear winding leakage and linear core magnetization effects.

The figure shows the equivalent circuit diagram for the wye-delta11 transformer.

  • w1a is the primary winding connected between the a-phase and the primary neutral point.

  • w1b is the primary winding connected between the b-phase and the primary neutral point.

  • w1c is the primary winding connected between the c-phase and the primary neutral point.

  • w2a is the secondary winding connected between the a-phase and the c-phase.

  • w2b is the secondary winding connected between the b-phase and the a-phase.

  • w2c is the secondary winding connected between the c-phase and the b-phase.

Display Options

You can display the transformer per-unit base values in the MATLAB® command window using the block context menu. To display the values, right-click the block and select Power Systems > Display Base Values.

Parameters

Main Tab

Rated apparent power

Apparent power flowing through the transformer when operating at rated capacity. The default value is 100e6 V*A.

Primary rated voltage

RMS line voltage applied to the primary winding under normal operating conditions. The default value is 4160 V.

Secondary rated voltage

RMS line voltage applied to the secondary winding under normal operating conditions. The default value is 24e3 V.

Rated electrical frequency

Rated or nominal frequency of the AC network to which the transformer is connected. The default value is 60 Hz.

Impedances Tab

Parameters in this tab are expressed in per-unit (pu). For more information, see Per-Unit System of Units.

Primary leakage resistance (pu)

Power loss in the primary winding. The default value is 0.01.

Primary leakage reactance (pu)

Magnetic flux loss in the primary winding. The default value is 0.001.

Secondary leakage resistance (pu)

Power loss in the secondary winding. The default value is 0.01.

Secondary leakage reactance (pu)

Magnetic flux loss in the secondary winding. The default value is 0.001.

Shunt magnetizing resistance (pu)

Magnetic losses in transformer core. The default value is 500.

Shunt magnetizing reactance (pu)

Magnetic effects of the transformer core when operating in its linear region. The default value is 500.

Initial Conditions Tab

Initial primary currents

Current through the primary leakage inductors at time zero. The default value is [0, 0, 0] A.

Initial secondary currents

Current through the secondary leakage inductors at time zero. The default value is [0, 0, 0] A.

Initial fluxes

Magnetic fluxes in the limbs of the core at time zero. The default value is [0, 0, 0] Wb.

Ports

The block has the following ports:

~1

Expandable three-phase port for primary winding

~2

Expandable three-phase port for secondary winding

n1

Electrical conserving port associated with the primary winding neutral point

Introduced in R2013b

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