MD1-0-E-505!06!00001 Generator Transformer Sizing Calculation

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A 30-01-2012 Issue for Approval B.M.SHIM D.W.SHIN S.H.HYUN

REV. DATE DESCRIPTION DSGN CHKD APPD

PROJECT :

TWO(2) x 500 MW MONG DUONG 1 THERMAL POWER PLANT

EMPLOYER :

CONSULTANT :

CONTRACTOR :

DESIGNED BY DATE TITLE :

B.M.SHIM 30-01-2012CALCULATION

FORGENERATOR TRANSFORMER SIZING

CHECKED BY DATE

D.W.SHIN 30-01-2012

APPROVED BY DATE PROJECT NUMBER DOCUMENT NUMBER REV.

S.H.HYUN 30-01-2012 ADB/MD1-TPIP/EPC150911 MD1-0-E-505-06-00001 A

FOR APPROVAL

APPROVED A

Approved without exception

APPROVED WITH COMMENTS AC

Approved Subject to Incorporation of comments

RETURNED FOR CORRECTION RT

Insufficient Information/ Detail

Resubmit for Approval

REJECTED RJ

Complete redesign required

RECEIVED FOR INFORMATION I

Returned without comments

RECEIVED FOR INFORMATION IC

Returned with comments

any obligations covered under contract

Engineer:

Discipline:

Date:

Note: Approval or comments does not relieve the Contractor of

Pöyry Energy

TWO(2) X 500MW

MONG DUONG 1 THERMAL POWER PLANT

Mark Brooks

Elec



MONG DUONG POWER STATION PH.1

Calculation for Generator Transformer Sizing Rev. A

MD1-0-E-505-06-0001_GEN. TR Size_RA i 30-01-2012

CONTENTS

1.0 PURPOSE ............................................................................................................................... 1

2.0 CODE & STANDARD .......................................................................................................... 1

3.0 SITE CONDITIONS .............................................................................................................. 1

4.0 CALCULATION CRITERIA ............................................................................................... 1

5.0 GIVEN DATA FOR GENERATOR TRANSFORMER SIZING ..................................... 2

6.0 CALCULATION FOR GENERATOR TRANSFORMER SIZING ................................ 2

7.0 DECISION OF GENERATOR TRANSFORMER SIZING ............................................. 3

<ATTACHMENTS>

ATTACHMENT#1 HEAT BALANCE DIAGRAM PRELIMINARY

ATTACHMENT#2 TRANSFORM SIZING CALCULATION

ATTACHMENT#3 LOADING GUIDE FOR OIL IMMERSED POWER TRANSFORMER

ATTACHMENTS:

1. Attachment#1 is the basis for maximum

output however this is still a preliminary

document. This value can only be considered

once the diagrams have been approved.





MD1-0-E-505-06-0001_GEN. TR Size_RA 1 30-01-2012

1.0 PURPOSE

This calculation is prepared to determine and verify the capacity of generator transformer

(525kV/21kV) for Mong Duong Thermal Power Plant Phase 1 Project in Vietnam .

2.0 CODE & STANDARD

IEC 60076: Power Transformers

3.0 SITE CONDITIONS

The site climatic conditions and the site design conditions are as follows :

a) Absolute minimum air temperature : -0.2℃

b) Absolute maximum air temperature : 39.5 ℃

c) Ambient design temperature : 39.5 ℃

d) Humidity range : 18-92%

4.0 CALCULATION CRITERIA

To calculate transformers sizing, the following points are considered.

a) The load for the Unit Auxiliary Transformer will not be considered.

b) The capacity of generator transformer will be capable for the operating power factor

range of 0.85 lagging to 0.9 leading at the generator terminals.

c) The maximum generator output based on the maximum turbine output(VWO condition)

is considered as follows ;

- Output : 552.955 MW (Refer to Attachment #1)

- Voltage : 21 kV ± 5% , 50 Hz

- Current : 15,202.3 Amperes

- Power Factor : 0.85 Lagging

d) Generator transformer voltage ratings are as follows ;

- High voltage : 525.0 kV WYE with grounded neutral

- Low voltage : 21.0 kV DELTA

e) Generator transformer will be operated at its ODAF rating under most condition.





MD1-0-E-505-06-0001_GEN. TR Size_RA 2 30-01-2012

5.0 GIVEN DATA FOR GENERATOR TRANSFORMER SIZING

a) The generator will be operated with max. continuous rating 650.535 MVA (552.955

MW at power factor 0.85 lagging).

DescriptionOperating Condition

(Case : VWO) Remark

Ambient Air Temperature 34.5 °C

Refer to Heat

Balance Diagrams

(Attachment #1)

Cooling Water Temperature 30.5 °C

Relative Humidity 85.0 %

Power Factor 0.85 lagging

Power at the Generator Terminal 552.955 MW

b) The generator will be operated in any of the following power factor ranges ;

- Case I : 0.90 P.F Leading

- Case II : 1.0 P.F

- Case III : 0.85 P.F Lagging

6.0 CALCULATION FOR GENERATOR TRANSFORMER SIZING

The generator output based on the maximum turbine output(VWO condition) is calculated asfollows ;

- Power factor 0.90 Leading :

MVA = 552.955 / 0.9 = 614.394 MVA at 39. 5°C amb. temp.

- Power factor 1.0 :


- Power factor 0.85 Lagging :


The capacity of generator transformer will be sized to cover the generator output at the power

factor ranges of 0.85 lagging to 0.9 leading as calculated above and therefore, generator

transformer capacity at 39. 5°C amb. temp should be :

620.538 MVA or above @ 0.90P.F. Leading

558.485 MVA or above @ 1.0P.F.

657.041 MVA or above @ 0.85P.F. Lagging





MD1-0-E-505-06-0001_GEN. TR Size_RA 3 30-01-2012

The rated capacity of transformer has been selected as 660MVA(based on ODAF) at the

ambient temperature 39.5°C, which has the output capabilities by ambient temperature as

listed below. Also, this capacity will satisfy to have minimum 1% margine for generator

output for all ambient temperature condition as shown in Attachment #2.

Ambient Temperature -0.2°C 34.5°C 39.5°C

Transformer Capacity

[MVA]842.1 682.8 660

* Note) The transformer capacity is calculated as per the loading factor at the different

ambient temperatures. (Refer to the attachment #3, IEC 60354 Loading Guide for Oil-

immersed Power Transformers, 3.3 Normal continuous Loading – Table 6. Acceptable load

factor for continuous duty K24 at different ambient temperatures (ON, OF and OD cooling)).

7.0 DECISION OF GENERATOR TRANSFORMER SIZING

Because the capacity of transformer means a value of input power to transformer, the capacity

of generator transformer should be equal or larger than the output of generator.

Based on the calculation results given above, the capacity of the generator transformer is

selected as below;

660MVA(220MVA x 3), ODAF, 525/21 kV

Z=14.5% @660MVA

On load HV tap changer ±17 x 1.3% taps





MD1-0-E-505-06-0001_GEN. TR Size_RA 4 30-01-2012

Attachment #1 Heat Balance Diagram preliminary





MD1-0-E-505-06-0001_GEN. TR Size_RA 5 30-01-2012

Attachment #2 Transformer Sizing Calculation



GENERATOR TRANSFORMER SIZING CALCULATION

1. GENERATOR RATING BASED ON 34.5Deg.C 2.TRANSFORMER IMPEDANCE DATA BAS

GEN MVA PF MW %z 14.50%

650.5353 0.85 552.955 X/R RATIO

552.9550 1 552.955 TOLERANCE 7.5%614.3944 0.9 552.955 MARGIN 101%

3.CALCULATION

MW MVAR MVA

GOUT(P) GOUT(Q) TIN(M) TIN(M)*1.01

0.85 552.955 342.7 650.535 657.0406

1 552.955 0.0 552.955 558.4846

0.9 552.955 -267.8 614.394 620.5384

0.85 552.955 342.7 650.535 657.0406

1 552.955 0.0 552.955 558.48460.9 552.955 -267.8 614.394 620.5384

0.85 552.955 342.7 650.535 657.0406

1 552.955 0.0 552.955 558.4846

0.9 552.955 -267.8 614.394 620.5384

34.5 552.955

39.5 552.955

-0.2 552.955

Temp Deg. ℃

Generator Output

MW

GOUT(P)

PF

TR Input(TIN(M)) Considering Margin

(MVA)





MD1-0-E-505-06-0001_GEN. TR Size_RA 6 30-01-2012

Attachment #3

Loading Guide for Oil-Immersed Power Transformers (IEC 60354)

MD1-0-E-505!06!00001 Generator Transformer Sizing Calculation

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