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Appendix B

Data Convert and Equipment Model of PSCAD/EMTDC Program

B.1 PSCAD/EMTDC Flow Chart

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B.2 Modeling of 500 kV Transmission Line Nam Theun 2 to Roi Et 2 Substation

Figure B.2.1 Equipments model of NTN 2 Power Plant

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Figure B.2.2 NTN 2 SVJ transmission line model

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Figure B.2.3 SVJ-RE 2 transmission line model

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Figure B.2.4 Equipment model of Roi Et 2 substation

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B.3 Saturation Transformer Model in PSCAD/EMTDC

Figure B.3.1 95 MVA power transformer V-I characteristic open circuit test

Saturation Characteristics of Tranformer V-I Curve( HV Current)

0

5

10

15

20

25

30

35

0 50 100 150 200 250 300 350

Current [A]

Voltage[kV]

Figure B.3.2 Saturation characteristic of 95 MVA transformer from manufacturer

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Saturation Characteristic of Transformer

( Transferred from V-I Curve )

0

20

40

60

80

100

120

140

0 50 100 150 200 250 300 350

Current [A]

Peak

Flux[Wb]

Figure B.3.3 Saturation characteristic of 95 MVA transformer converted from V-I

curve

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Figure B.3.4 Voltage and current open circuit test of step down 333.3 MVA

autotransformer

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Saturation Characteristics of Tranformer V-I Curve

( Reference HV Curve )

0

50

100

150

200

250

0 100 200 300 400 500 600 700

Current [A]

Voltage[kV]

Figure B.3.5 Saturation characteristic of 333.33 MVA autotransformer from

manufacturer

Saturation Characteristic of Transformer

( Transferred from V-I Curve )

0

100

200

300

400

500

600

700

800

900

1000

0 100 200 300 400 500 600 700

Current [A]

PeakFlux

[Wb]

Figure B.3.6 Saturation characteristic of 333.3 MVA transformer converted from V-Icurve

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B.3.1 Equation of Saturation Transformer Model in PSCAD/EMTDC

PSCAD/EMTDC uses a curve fitting algorithm, which is described in

transformer loss and saturation, to present transformer saturation in a smooth and

continuous from. The algorithm requires three parameters:

1. Air Core Reactance (XAIR)

- Air Core Reactance (XAIR) is obtained based on the two highest points:

.MAIR

M BASE

XI Z

=

[ p.u ]

2. Rated Magnetizing Current (IMR)

- Rated Magnetizing Current (IMR) is calculated using a point closest to

the rated Flux:

. .100R MMR

M R

II

I

= [ %]

3. Knee Point (XKNEE)

- Knee Point (XKNEE) is calculated based on the highest point:

.AIR MKNEE

R

L IX

= [ p.u]

Note:

1. As a rule, XKNEE should be between 1.0 to 1.25 p.u

2. Always select ideal transformer if saturation is modeled.

3. Minimum no load loss is automatically 0.1% if saturation is

selected.

- Rate current of single phase power transformer 95 MVA (18/525 kV)

- 5.278MVA

I kAkV

= = (at 18 kV side)

- Rate current of autotransformer 333.3 MVA (525/242/22 kV)

- 0.837MVA

I kAkV

= = (at 230 kV side)