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Multiphase transformers can represent either a 1, 2, or 3-phase transformer. In the corresponding Excel tab, there are columns for declaration of up to 6 connection points (3 for Winding From end and 3 for Winding To end).

The sending and receiving connection points must be filled correspondingly:

  • For example, if Winding From/Bus 1 is filled, Winding To/Bus 1 must be filled as well. The unused connection points can be left empty. However, these empty fields must be located after any filled connection point.
  • For example, a data in which Winding From/Bus 2 and Winding To/Bus 2 fields are filled out but Winding From/Bus 1 and Winding To/Bus 1 are empty is not valid and it causes an error.

Finally, the sending and receiving points can be connected to different phases. For example Winding From/Bus 1 can be connected to phase A while Winding To/Bus 1 is connected to phase B.

In summary, to represent:

  • a single-phase transformer, fill only the 2nd (Winding From/Bus 1) and 9th (Winding To/Bus 1) columns to declare connection points.
  • a two-phase transformer, fill 2nd and 3rd columns (Winding From/Bus1 and Winding From/Bus 2) as well as 9th and 10th columns (Winding To/Bus 1 and Winding To/Bus 2) to assign connection points.
  • a three-phase line, fill 2nd, 3rd and 4th columns (Winding From/Bus1, Winding From/Bus 2, Winding From/Bus 3) as well as 9th, 10th and 11th columns (Winding To/Bus 1, Winding To/Bus 2 and Winding To/Bus 3) to assign connection points.

The table below shows the parameter list for multiphase transformer.

Expand
titleMultiphase Transformer Parameters


Symbol

Description

Unit

ID

Transformer name

a unique name

Number of PhasesPhase count in use1, 2, or 3

Winding From

Bus 1

Primary side: Bus 1

a unique name

Bus 2

Primary side: Bus 2

a unique name

Bus 3

Primary side: Bus 3

a unique name

V (kV)

Primary winding nominal voltage (phase-to-phase)

kV

S_base (kVA)

Nominal power in primary side

kVA

R (pu)

Primary winding resistance

p.u.

Conn. type (**)

Primary winding connection type

‘wye’ and ‘delta’

Winding To

Bus 1

Secondary side: Bus 1

a unique name

Bus 2

Secondary side: Bus 2

a unique name

Bus 3

Secondary side: Bus 3

a unique name

V (kV)

Secondary winding nominal voltage (phase-to-phase)

kV

S_base (kVA)

Nominal power in secondary side

NOT APPLICABLE

R (p.u.)

Secondary winding resistance

p.u.

Conn. type (**)

Secondary winding connection type

‘wye’ and ‘delta’

Mutual impedance (*)

0: No mutual impedance, 1: With mutual impedance

-

Tap 1

Initial tap position: winding 1

Integer between Lowest and Highest Tap

Tap 2

Initial tap position: winding 2

Tap 3

Initial tap position: winding 3

Lowest Tap

The lowest tap position

Integer value

Highest Tap

The highest tap position

Integer value

Min Range (%)

Max voltage buck

0 < value < 100

Max Range (%)

Max voltage boost

value > 0

X (pu)

Total reactance

p.u.

Z0 leakage (pu)

Zero-sequence impedance

transformer p.u.

Z1 leakage (pu)

Positive-sequence impedance

transformer p.u.

X0/R0

Zero-sequence reactance to resistance ratio

ratio

X1/R1

Positive-sequence reactance to resistance ratio

ratio

No Load Loss (kW)

No-load power loss

NOT APPLICABLE


Background Color
color#D3D3D3


Note: 

(*) For a transformer with no mutual impedance (Mutual impedance = 0) use R (pu) and X (pu) and for transformer with mutual impedance use Z0 leakage, Z1 leakage, X0/R0, X1/R1 and No load loss.

(**) Four types of winding configurations are supported: 'DD0', 'YgYg0', 'DYg1', 'YgD1'.



Available I/O pins

No

Pin’s Description

Pin Type

Value/Unit

Instruction

1

Get sending end current magnitude of wire j

O

A (RMS)

transformerID/ImagFromj

where j is 1, 2 or 3

2

Get receiving end current magnitude of wire j

O

A (RMS)

transformerID/ImagToj

where j is 1, 2 or 3

3

Get sending end current angle of wire j

O

Degree

transformerID/IangFromj

where j is 1, 2 or 3

4

Get receiving end current angle of wire j

O

Degree

transformerID/IangToj

where j is 1, 2 or 3

5

Set/Get tap position

I/O

Integer between [min_tap, max_tap]

transformerID/tap_j

where j is 1, 2 or 3

Example

See the Multiphase Transformer page in ‘phasor08_IEEE13.xls’ file in demo ‘PHASOR-08’.