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

Pöyry Energy TWO(2) X 500MW MONG DUONG 1 THERMAL POWER PLANT

A

APPROVED Approved without exception

AC

APPROVED WITH COMMENTS Approved Subject to Incorporation of comments

RT

RETURNED FOR CORRECTION Insufficient Information/ Detail Resubmit for Approval

RJ

REJECTED Complete redesign required

I

RECEIVED FOR INFORMATION Returned without comments

IC

RECEIVED FOR INFORMATION

FOR APPROVAL

Returned with comments Note: Approval or comments does not relieve the Contractor of any obligations covered under contract

Engineer: Discipline:

Mark Brooks Elec

Date:

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

30-01-2012

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

CALCULATION FOR GENERATOR TRANSFORMER SIZING

MONG DUONG POWER STATION PH.1 Calculation for Generator Transformer Sizing

Rev. A

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

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

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MONG DUONG POWER STATION PH.1 Calculation for Generator Transformer Sizing

1.0

Rev. A

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 :

c) Ambient design temperature

℃ : 39.5 ℃ : 39.5 ℃

d) Humidity range

: 18-92%

a) Absolute minimum air temperature

: -0.2

b) Absolute maximum air temperature

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

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MONG DUONG POWER STATION PH.1 Calculation for Generator Transformer Sizing

5.0

Rev. A

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). Operating Condition

Description

(Case : VWO)

Ambient Air Temperature

34.5 °C

Cooling Water Temperature

30.5 °C

Relative Humidity

85.0 %

Power Factor

0.85 lagging

Power at the Generator Terminal

552.955 MW

Remark

Refer to Heat Balance Diagrams (Attachment #1)

b) The generator will be operated in any of the following power factor ranges ; - Case I - Case II - Case III

6.0

: : :

0.90 P.F Leading 1.0 P.F 0.85 P.F Lagging

CALCULATION FOR GENERATOR TRANSFORMER SIZING The generator output based on the maximum turbine output(VWO condition) is calculated as follows ; -

Power factor 0.90 Leading : MVA = 552.955 / 0.9 = 614.394 MVA at 39. 5°C amb. temp.

-

Power factor 1.0 : MVA = 552.955 / 1.0 = 552.955 MVA at 39. 5°C amb. temp.

-

Power factor 0.85 Lagging : MVA = 552.955 / 0.85 = 650.535 MVA at 39. 5°C amb. temp.

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

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MONG DUONG POWER STATION PH.1 Calculation for Generator Transformer Sizing

Rev. A

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 Oilimmersed 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

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MONG DUONG POWER STATION PH.1 Calculation for Generator Transformer Sizing

Rev. A

Attachment #1 Heat Balance Diagram preliminary

MD1-0-E-505-06-0001_GEN. TR Size_RA

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MONG DUONG POWER STATION PH.1 Calculation for Generator Transformer Sizing

Rev. A

Attachment #2 Transformer Sizing Calculation

MD1-0-E-505-06-0001_GEN. TR Size_RA

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GENERATOR TRANSFORMER SIZING CALCULATION 1. GENERATOR RATING BASED ON 34.5Deg.C GEN MVA PF 650.5353 0.85 552.9550 1 614.3944 0.9

2.TRANSFORMER IMPEDANCE DATA BASED ON 39.5Deg.C %z 14.50% X/R RATIO TOLERANCE 7.5% MARGIN 101%

MW 552.955 552.955 552.955

3.CALCULATION Temp Deg.

℃

Generator Output MW GOUT(P)

-0.2

552.955

34.5

552.955

39.5

552.955

TR Input(TIN(M)) PF 0.85 1 0.9 0.85 1 0.9 0.85 1 0.9

MW GOUT(P) 552.955 552.955 552.955 552.955 552.955 552.955 552.955 552.955 552.955

MVAR GOUT(Q) 342.7 0.0 -267.8 342.7 0.0 -267.8 342.7 0.0 -267.8

MVA TIN(M) 650.535 552.955 614.394 650.535 552.955 614.394 650.535 552.955 614.394

Considering Margin (MVA) TIN(M)*1.01 657.0406 558.4846 620.5384 657.0406 558.4846 620.5384 657.0406 558.4846 620.5384

Loading Factor (@OD)

Applied MVA

1.11

842.1

0.90

682.8

0.87

660.0

MONG DUONG POWER STATION PH.1 Calculation for Generator Transformer Sizing

Rev. A

Attachment #3 Loading Guide for Oil-Immersed Power Transformers (IEC 60354)

MD1-0-E-505-06-0001_GEN. TR Size_RA

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