Single phase three winding transformer

This section describes single phase three winding transformer

The single-phase three-winding transformer component models three coupled windings on the same core. The magnetization inductance Lm can be linear or with saturation, it is modeled on the primary side of the transformer. Core losses are modeled as Rm resistance located on the primary side of the transformer. Also, it is possible to neglect Lm and Rm by selecting Lm/Rm neglected in the Core model property. Finally, Hysteresis can also be simulated for slower dynamics. For more information, please refer to the Core model section.

The single-phase three-winding transformer schematic symbol and input parameters are given in Table 1.

Table 1. Single phase three winding transformer component in the Schematic Editor core library
component component dialog window component parameters

Single phase three winding transformer
  • Input parameters option – SI/p.u.
  • Nominal Power of the transformer in VA (Sn)
  • Nominal frequency in Hz (fn)
  • Rated voltage of first (primary) winding (V1)
  • Rated voltage of second winding (V2)
  • Rated voltage of third winding (n3)
  • Leakage inductance of first(primary) winding (L1)
  • Initial current in first winding (I1)
  • Leakage inductance of second winding (L2)
  • Initial current in second winding (I2)
  • Leakage inductance ofthird winding (L3)
  • Initial current in third winding (I3)
  • Core model - Linear, Non-Linear, Rm/Lm neglected
  • Magnetization Inductance (Lm)
  • Resistance of first winding(R1)
  • Resistance of second winding (R2)
  • Resistance of third winding (R3)
  • Equivalent resistance representing the iron core losses (Rm)
  • Import from PU button

  • Embedded coupling 1-2 - inserts a coupling component (Ideal Transformer based or TLM) between winding 1 and 2.
  • Embedded coupling 1-3 - inserts a coupling component (Ideal Transformer based or TLM) between winding 1 and 3.
  • Type of coupling component - defines whether the inserted coupling component is a core or a device coupling. Device coupling is available only for the Ideal Transformer based coupling.
  • TLM 1-2/Embedded components ratio - Defines how coupling to embedded inductors ratio will be calculated. Related to coupling between winding 1 and 2. Available only for the TLM coupling.
  • TLM 1-3/Embedded components ratio - Defines how coupling to embedded inductors ratio will be calculated. Related to coupling between winding 1 and 3. Available only for the TLM coupling.
  • Ratio - Used to specify coupling to embedded inductors ratio if Manual option is selected in TLM/Embedded components ratio property.

A schematic block diagram of the single-phase three-winding transformer block with the corresponding component arrangement and naming is shown in Figure 1.

Figure 1. The schematic block diagram of a single-phase three-winding transformer with corresponding component naming

Embedded coupling

There are two possible options for embedded coupling in the single phase three winding transformer, Ideal Transformer based coupling and TLM coupling. Also, it is possible to insert embedded coupling between winding 1 and 2, 1 and 3, and both of them.

If Embedded coupling is set to Ideal Transformer, Ideal Transformer based coupling will be placed between two windings of transformer.

In Figure 2 and Figure 3, respectively, are given visual representations of division of circuit among standard processing cores, in case where Embedded coupling 1-3 is set to Ideal Transformer and in case where both Embedded coupling 1-2 and Embedded coupling 1-3 are set to Ideal Transformer.

Figure 2. Representation of circuit division between cores where Embedded coupling 1-3 is set to 'Ideal Transformer'
Figure 3. Representation of circuit division among cores where both Embedded coupling 1-2 and Embedded coupling 1-3 are set to 'Ideal Transformer'

If Embedded coupling is set to TLM, secondary winding inductor will be replaced with TLM coupling component. Inductance will be divided between coupling and embedded inductors (inductors will be hidden in the TLM). TLM to embedded inductors ratio can be determined by compiler, but also it can be specified explicitly. If Automatic option is selected, ratio will be determined by discretization method. If Manual option is selected, ratio can be explicitly set to meet user requirements. For more information on TLM couplings please refer to Core couplings - TLM.

In Figure 4 and Figure 5, respectively, are given visual representations of division of circuit among standard processing cores, in case where Embedded coupling 1-3 is set to TLM and in case where both Embedded coupling 1-2 and Embedded coupling 1-3 are set to TLM.

Figure 4. Representation of circuit division between cores where Embedded coupling 1-3 is set to 'TLM'
Figure 5. Representation of circuit division among cores where both Embedded coupling 1-2 and Embedded coupling 1-3 are set to 'TLM'

State variable naming for the single-phase three-winding transformer (internal to the component)

Analog output variable name Description
(name).L1 Primary winding current
(name).L2 Second winding current
(name).L3 Third winding current
(name).Lm Magnetizing current