Three-phase two windings transformer#

The Three-phase two windings transformer block is a model of a three-phase two windings transformer.

Model description

The model presented in the block is represented by three single-phase transformers with three windings connected to each other in a user-selected way. The model is symmetrical, the phase parameters are taken the same for each of three phases and are determined in one of three ways. So, setting parameters of equivalent circuit is possible in SI system (then the user needs to enter windings parameters on their own (rated linear voltages, V, resistances, Ohm and inductance, Hn), in relative units (then the user needs to enter transformer parameters (rated linear voltages, V, resistance, s.u., inductance, s.u., as well as nominal power, VA and rated frequency, Hz), as well as by entering the catalog parameters of the transformer (in this case, the equivalent circuit parameters will be calculated automatically from the data provided).

The procedure for calculating the equivalent circuit parameters from relative units and catalog data is described in the corresponding article “Procedure for calculating the parameters of transformer models”.

Selecting the desired winding connection group

Within the block it is possible to select the required circuit of transformer windings. Each winding can be connected by one of two circuits:

“star” (this circuit is denoted by Y) - the ends of the phase windings are connected at one point;
“triangle”-1 (the circuit is denoted by D1) - the end of the winding of each phase is connected to the beginning of the winding of the next one (end of A - with the beginning of B, end of B - with the beginning of C, end of C - with the beginning of A);
“triangle”-11 (the circuit is denoted by D11) - the end of the winding of each phase is connected to the beginning of the winding of the previous one (end of A - with the beginning of C, end of B - with the beginning of A, end of C - with the beginning of B).

The Fig. 1 (see below) shows the directions of current flow in the windings depending on the circuit and group of connections.

LinearThreePhaseTransformer — Fig. 1 Directions of current flow in windings#

The choice of the necessary connection circuit of windings is presented by the following options: Y/Y, Y/D-1, Y/D-11, D-1/D-1, D-1/Y, D-1/D-11, D-11/D-11, D-11/Y and D-11/D-1. The influence of the winding connection group on the transformation factor is described in the article and is automatically taken into account in the block.

The given connection circuits make it possible to provide various shifts of phase EMF from 0 to +/-60 degrees with step of 30 degrees. It is possible to implement an additional shift of +/- 120 degrees by changing the order of connecting outputs of winding D to the mains, which is given in the table below.

Group of connections	Phase shift, degrees	Winding connection circuit and group	Circuit and group of windings connections in the block	Procedure for connecting the outputs of winding connected in D to circuit phases
0	0	Y/Y-0	Y/Y	-
0	0	D/D-0	D-1/D-1	abc
1	-30	Y/D-1	Y/D-1	abc
1	-30	D/Y-1	D-11/Y	abc
2	-60	D/D-2	D-11/D-1	abc
5	-150	Y/D-5	Y/D-1	bca
5	-150	D/Y-5	D-11/Y	cab
7	+150	Y/D-7	Y/D-11	cab
7	+150	D/Y-7	D-1/Y	bca
10	+60	D/D-2	D-1/D-11	abc
11	+30	Y/D-11	Y/D-11	abc
11	+30	D/Y-11	D-1/Y	abc

1. Properties#

Property	Default value	Description	Units of measurement
Method of specifying model parameters: SI; PU; Specification	SI	-	-
Primary windings connection scheme: Y; D1; D11	Y	-	-
Secondary windings connection scheme: Y; D1; D11	Y	-	-
Primary winding parameters, U\(_{1}\); R\(_1\); L\(_1\)	230000.0;4.3218;0.45856	Available, when `Method of specifying model parameters` - `SI`	V; Ohm; H
Secondary winding parameters, U\(_{2}\); R\(_2\); L\(_2\)	115000.0;0.7938;0.084225	Available, when `Method of specifying model parameters` - `SI`	V; Ohm; H
Magnetization branch parameters, R\(_m\); L\(_m\)	1080400.0;2866.0	Available, when `Method of specifying model parameters` - `SI`	Ohm; H
Nominal power	2.5E8	Available, when `Method of specifying model parameters` - `PU` or `Specification`	VA
Nominal frequency	50.0	Available, when `Method of specifying model parameters` - `PU` or `Specification`	Hz
Primary winding parameters, U\(_{1}\); R\(_1\); L\(_1\)	230000.0;0.02; 0.68	Available, when `Method of specifying model parameters` - `PU`	V; r.u.; r.u.
Secondary winding parameters, U\(_{2}\); R\(_2\); L\(_2\)	115000.0;0.02; 0.68	Available, when `Method of specifying model parameters` - `PU`	V; r.u.; r.u.
Magnetization branch parameters, R\(_m\); L\(_m\)	500.0;500.0	Available, when `Method of specifying model parameters` - `PU`	r.u.; r.u.
Nominal voltage of primary winding	230000.0	Available, when `Method of specifying model parameters` - `Specification`	V
Nominal voltage of secondary winding	115000.0	Available, when `Method of specifying model parameters` - `Specification`	V
Nominal short circuit losses	35000.0	Available, when `Method of specifying model parameters` - `Specification`	W
Nominal impedance voltage	10.5	Available, when `Method of specifying model parameters` - `Specification`	%
Nominal no load losses	10000.0	Available, when `Method of specifying model parameters` - `Specification`	W
Nominal no load current	0.5	Available, when `Method of specifying model parameters` - `Specification`	%
Initial values of phase A windings currents, I\(_{1А}\); I\(_{2А}\)	0.0;0.0	-	А
Initial values of phase B windings currents, I\(_{1B}\); I\(_{2B}\)	0.0;0.0	-	А
Initial values of phase C windings currents, I\(_{1C}\); I\(_{2C}\)	0.0;0.0	-	А
Initial values of phase A magnetization branch current and voltage, I\(_{MА}\); U\(_{MА}\)	0.0;0.0	-	A; V
Initial values of phase B magnetization branch current and voltage, I\(_{MB}\); U\(_{MB}\)	0.0;0.0	-	A; V
Initial values of phase C magnetization branch current and voltage, I\(_{MC}\); U\(_{MC}\)	0.0;0.0	-	A; V

2. Inputs and outputs#

Parameters	Input/Output	Description	Units of measurement	Port type
А	Input	-	-	Electronics
V	Input	-	-	Electronics
С	Input	-	-	Electronics
N	Output	Available, when `Primary windings connection scheme` - `Y`	-	Electronics
a	Output	-	-	Electronics
b	Output	-	-	Electronics
c	Output	-	-	Electronics
n	Output	Available, when `Secondary windings connection scheme` - `Y`	-	Electronics

In order to see the connection capabilities of the block, you need to go to page Description of blocks ports