DG Sizing

210 MWnet COAL FIRED POWER PLANT, MINDANAO, PHILIPPINES

Calculation of Emergency DG Set Doc. No. 13002 - Y1F001 (Rev. 2)

CONTENTS

CLAUSE NO.

DESCRIPTION

1.0

PURPOSE

2.0

SIZING CRITERIA

3.0

LEGEND

4.0

FORMULAE USED

5.0

EQUIPMENT DATA

6.0

SIZING CALCULATION

7.0

FINAL SIZING OF DG SET

ATTACHMENT ANNEXURE - 1

STATION AUXILIARY BASE LOAD DURING SAFE SHUT - DOWN & STANDSTILL CONDITIONS

ANNEXURE - 2

SINGLE LINE DIAGRAM - EMERGENCY DG SET



1.0 PURPOSE The purpose of this calculation is to determine the sizing of Emergency Diesel Generator Set for catering the loads during safe shut-down & standstill conditions of the power plant. 2.0 SIZING CRITERIA The sizing of Emergency DG Set will be such that it should cater the maximum of load requirement of the following two cases during safe shut-down & standstill conditions : Case -1 (Load Criteria) - The sum of the following loads : a) Station Base Input Loads as per enclosed Annexure - 1, except Fire Water Pump Motor (largest motor) b) Running Load of Fire Water Pump Motor (largest motor) Case - 2 (Voltage Drop Criteria) - The sum of the following loads : a) Station Base Input Loads as per enclosed Annexure - 1, except Fire Water Pump Motor (largest motor) b) Starting Load of Fire Water Pump Motor (largest motor) 3.0 LEGEND Refer Electrical Single Line Diagram given in enclosed Annexure - 2 Eg

= EMF generated in DG Set

VLV

= Voltage at Bus of 480V Emergency Switchgear

VMS

= Voltage at terminal of largest motor during starting

Ig

= Current through DG Set

Ib

= Current through Station Base Loads

Xdg'

= Transient Reactance of DG Set

Rg

= Resistance of DG Set

Zg

= Impedance of DG Set

ZC1

= Impedance of Cables between DG Set and 480V Emergency Switchgear

ZC2

= Impedance of Cables between 480V Emergency Switchgear and largest motor

ZLV

= Impedance of Station Base LV Loads

ZMS

= Impedance of largest motor during starting condition

ZEL

= (ZC2+ ZMS ) II ZLV

152156824.xls.ms_office - Calculation

Page 2 of 10



4.0 FORMULAE USED a)

Base = Base kV2 / Base MVA Impedance (in ohms)

b)

Per Unit = Impedance in ohms / Base Impedance in Ohms Impedance (in p.u.)

c)

Zp.u.-new = Zp.u.-old x MVAbase-new / MVAbase-old x (kVbase-old / kVbase-new ) 2

d)

Load = Base MVA / Load MVA x (Load Voltage / Base Voltage)2 Impedance (in p.u.)

e)

Load = Base MVA / Load MVA x (Load Voltage / Base Voltage)2 x Cos θ, Resistance where Cos θ = load power factor (in p.u.)

f)

Load = Base MVA / Load MVA x (Load Voltage / Base Voltage)2 x Sin θ Reactance (in p.u.)

5.0 EQUIPMENT DATA a)

DG Set

Rating Voltage Xdg'

= = = = = =

1250 0.48 14.00 0.14 23.00 0.0061

Fire Water Pump Motor kW Rating (largest motor) Voltage Rating Running p. f. Efficiency Full Load Current Starting / Full Load Current Starting Input kVA Starting p. f. Starting Input kW Starting Input kVAR

= = = = = = = = = =

150.00 0.46 0.85 0.930 238.16 6.0 1138.52 0.25 284.630 1102.367

c)

Cable C1

Size No. of run Length Resistance per run Reactance per run Total Resistance Total Reactance

= 1C-500 mm2, XLPE = 4 = 110.00 Meters = 0.0543 Ohms / kM = 0.0948 Ohms / kM = 0.0015 Ohms = 0.0026 Ohms

d)

Cable C2

Size No. of run Length Resistance per run Reactance per run Total Resistance Total Reactance

= 3C-240 mm2, XLPE = 2 = 275.00 Meters = 0.0998 Ohms / kM = 0.0943 Ohms / kM = 0.0137 Ohms = 0.0130 Ohms

Xdg' / Rg Rg b)


kVA (assumed) kV % on its own base (assumed) p.u. on its own base (as per IEEE) p.u. on its own base kW kV

Amps 5 times with IEC tolerance (+20%) kVA kW kVAR

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6.0 SIZING CALCULATION 6.1 Calculation for Impedances Let,

a)

b)

Base kVA

=

1250 kVA

Base kV

=

0.48 kV

Base Impedance

=

0.1843 Ohms

Station Auxiliary LV Input Base Loads except largest motor (Refer Annexure - 1) Rated Voltage = Loads in kW = Loads in kVAR = Loads in kVA Power factor During pre-start condition of largest motor, the terminal voltage at all loads assumed in terms of rated voltage Real part of impedance of these loads Imaginary part of impedance of these loads ZLV, during pre-start condition of largest motor,

= = =

During starting condition of largest motor, the terminal voltage at all loads assumed in terms of rated voltage Real part of impedance of these loads Imaginary part of impedance of these loads ZLV, during starting condition of largest motor, impedance in p. u.

= = = =

0.89 > 0.75 as per specification 0.9655 p. u. 0.6553 p. u. 0.965488603508128+0.65526417696221j

= 0.0061 p. u. = 0.1400 p. u. = 0.00608695652173913+0.14j

0.2521 p. u. = = 0.9763 p. u. = 0.252082429108796+0.97631104980988j

Cable C1 Real part of impedance Imaginary part of impedance ZC1

e)

= 1.1001 p. u. = 0.7466 p. u. = 1.10005487270052+0.746592500578708j

Fire Water Pump Motor Real part of impedance during starting condition Imaginary part of impedance during starting condition ZMS

d)

779.306 kVA at 460V 0.8274 0.95 > 0.90 as per specification

DG Set Rg Xdg' Zg

c)

460 V 644.822 kW at 460V 437.632 kVAR at 460V

= 0.0081 p. u. = 0.0141 p. u. = 0.00810139973958333+0.0141438802083333j

Cable C2 Real part of impedance Imaginary part of impedance ZC2


= 0.0744 p. u. = 0.0703 p. u. = 0.0744493272569444+0.0703464084201389j

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6.2 Calculation for Sizing of DG Set for Case - 1 a)

Calculation for Sizing of Generator

1)

Station Input Base kW Loads

2)

3)

b)

Station auxiliary LV input base loads except largest motor = (Refer Annexure - 1) Running load of largest motor =

644.822 kW

Total of above items

=

789.984 kW

With 15% margin

=

118.498 kW

Total kW requirement

=

908.481 kW

145.161 kW

Station Input Base kVAR Loads Station auxiliary LV input base loads except largest motor = (Refer Annexure - 1) Running load of largest motor =

437.632 kVAR


=

527.595 kVAR

With 15% margin

=

79.139 kVAR

Total kVAR requirement

=

606.735 kVAR

89.963 kVAR

Required Rating of Generator kVA rating Voltage Power factor

= = =

1250 kVA 0.48 kV 0.80

kW rating of Generator

= >

kVAR rating of Generator

= >

750.000 kVAR 606.735 kVAR

Total requirement for station input base kW loads including largest motor

=

908.481 kW

Considering efficiency of Generator

=

0.95

Required rating of Engine

=

956.296 kW

1000.000 kW 908.481 kW

Calculation for Sizing of Diesel Engine


Page 5 of 10



6.3 Calculation for Sizing of DG Set for Case - 2 a)

Calculation for Sizing of Generator

1)

Motor Pre - start Condition Refer Equivalent Circuit - 1 of enclosed Annexure - 2 Let at this condition the voltage at Bus VLV

2)

ZLV in p. u.

= 0.48 kV with angle Zero = 1 p. u. = 1.10005487270052+0.746592500578708j

Ib = Ig = VLV / ZLV in p. u.

= 0.622371570056748-0.422395244372744j

(Zg + ZC1) in p. u.

= 0.0141883562613225+0.154143880208333j

Ig*(Zg + ZC1) in p. u.

= 0.0739400715120456+0.0899416745296506j

Eg = VLV + Ig*(Zg + ZC1) in p. u.

= 1.07394007151205+0.0899416745296506j = 1.07769976 (within ±10% range of AVR control)

Motor Starting Condition Refer Equivalent Circuit - 2 of enclosed Annexure - 2 Eg in p. u.

= 1.07394007151205+0.0899416745296506j

(Zg + ZC1) in p. u.

= 0.0141883562613225+0.154143880208333j

ZLV in p. u.

= 0.965488603508128+0.65526417696221j

ZMS in p. u.

= 0.252082429108796+0.97631104980988j

(ZC2+ ZMS) in p. u.

= 0.32653175636574+1.04665745823002j

(ZC2 + ZMS)*ZLV in p. u.

= -0.370574448473838+1.22450041028489j

(ZC2 + ZMS + ZLV) in p. u.

= 1.29202035987387+1.70192163519223j

ZEL = (ZC2 + ZMS)*ZLV / (ZC2+ ZMS + ZLV) in p. u.

= 0.351569291653108+0.48463402435267j

(Zg + ZC1+ ZEL) in p. u.

= 0.36575764791443+0.638777904561003j

Ig = Eg / (Zg + ZC1+ ZEL) in p. u.

= 0.83101026610059-1.20541381549433j

Ig*(Zg + ZC1) in p. u.

= 0.197597832489279+0.110992306253151j

VLV = Eg - Ig*(Zg + ZC1) in p. u.

= 0.876342239022771-0.0210506317235004j = 0.87659503 p. u. 420.7656 V 91.47 of rated voltage, which is as per assumption = and acceptable > 75 % as per specification


Page 6 of 10


3)


ZMS / (ZC2 + ZMS) in p. u.

= 0.918528030130026+0.0457132765495565j

VMS = VLV*ZMS / (ZC2 + ZMS) in p. u.

= 0.805907203878842+0.020724879834526j = 0.80617364 p. u. = 386.9633 V = 84.12 % of rated voltage, which is acceptable > 80 % as per specification

Required Rating of Generator It is observed from the above calculation, the voltages available at LV load bus and largest motor during pre-start and starting conditions of this motor are within acceptable ranges. Required rating of Generator kVA rating = Voltage = Power factor

4)

1250 kVA 0.48 kV 0.80

Calculation for Sizing of Diesel Engine Station Auxiliary LV input base loads except largest motor = (Refer Annexure - 1)

644.822 kW

With 15% margin

=

96.723

Starting load of largest motor

=

284.630 kW


=

1026.176 kW

Considering efficiency of Generator

=

0.95

Maximum short time kW demand on Engine

=

1080.185 kW

Considering overloading capacity of Engine

=

1.1

Required rating of Engine

=

981.986 kW

7.0 FINAL SIZING OF DG SET 7.1 Selection of Generator Rating kVA rating of Generator will be the maximum of the calculated kVA ratings for the above Cases 1 and 2 Therefore, calculated maximum kVA rating of Generator

=

1250 kVA

7.2 Selection of Engine Rating kW rating of Engine will be the maximum of the calculated kW ratings for the above Cases 1 and 2 Therefore, calculated maximum kW rating of Engine


=

981.986 kW

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7.3 Selection of DG Set Rating (Minimum) Selected rating of Engine

=

1000 kW

= = = =

1250 kVA 0.48 kV 0.80 14.00 % on its own base (without any positive tolerance)

Selected rating of Generator kVA rating Voltage Power factor Xdg'

AVR Range =

±10 %

7.4 Special Requirement for Fire Water Pump Motor Starting / Full Load Current at rated voltage


=

5 times with IEC tolerance (± 20%)

Page 8 of 10



ANNEXURE - 1 STATION AUXILIARY BASE LOAD DURING SAFE SHUT - DOWN & STANDSTILL CONDITIONS

Sl. No.

Load Description

1 2 3 4

Turning Gear for Turbine Turbine Lube Oil Pump Emergency CCW Pump Auxiliary Cooling Water Pump Stand-by Motor for Rotor Drive Unit (GAH) Scanner Cooling Air Fan Jocky Pump Lube Oil Pump for Gas Air Preheater (GAH) Sector Plate Drive Unit for GAH Elevators Plant DC / UPS System 138kV Switchyard AC Emergency Lighting Load Ventilation fan for Battery Room Fuel Oil Pump for Emergency DG

5 6 7 8 9 10 11 12 13 14 15

Rating kW

p. f.

11.00 65.00 45.00 75.00

0.84 0.81 0.85 0.81

Efficiency 0.907 0.925 0.915 0.926

No. of Running Unit

Input Load Requirement kW

2 2 2 2

24.256 140.541 98.361 161.987

Remarks

kVAR 15.668 101.750 60.958 117.277

5.50 0.86

0.898

2

12.249

7.268

15.00 0.86 22.00 0.84

0.886 0.910

2 1

33.860 24.176

20.091 15.616

0.75 0.80

1.382

0.25 7.00 100.00 20.00 60.00 2.20 0.40

0.814

2

1.843

0.80 0.86 0.75 0.80 0.95 0.82 0.82

0.858 0.886 0.900 0.873 0.873

6 2 1 1 1 2 1

1.748 15.801 100.000 20.000 66.667 5.040 0.458

1.311 9.376 88.192 Input rating 15.000 Input rating 21.912 3.518 0.320

16

Main Cooling Water PumpDischarge Valve

3.00 0.82

0.870

2

6.897

4.814

17

Other Valve

0.75 0.82

0.870

3

2.586

1.805

716.469

486.258

Total Considering overall load factor

=

0.90

Total Input LV Load Requirement except Fire Water Pump Motor (largest motor)

=

644.822

437.632

Fire Water Pump

1

161.290

99.959

Considering overall load factor

=

0.90

Input LV Load Requirement for Fire Water Pump Motor (largest motor)

=

145.161

150.00 0.85

0.930

89.963

NOTE : 1) 2) a) b)

For the list of loads during safe shut-down & standstill conditions of the power plant, refer Doc. No. 13002 - A0G301 - Sizing Critera of Emergency Diesel Generator. The following loads have been envisaged to be fed Plant DC / UPS System : Plant DC load including DCS load at 125V DC Plant UPS System consisting of loads of the following items at 120V, 1 Ph, AC : - DCS Load - Turbine Control system - Communication Systems, consisting of Telephone System, Paging System with Radio Paging and Voice Recordind System - Server / PC Network in Administration Building - Fire Alarm Panel - Siren - Emmission Monitoring System

3) No. and rating of drives, listed above, are preliminary and indicative only. The same will be revised based on the final load list.

152156824.xls.ms_office - Base_Load

Page 9 of 10



ANNEXURE - 2 SINGLE LINE DIAGRAM - EMERGENCY DG SET Eg

Eg

Zg

Zg

Emergency DG Set 1250 kVA, 480V, 0.8 p.f., Xdg' = 14% ZC1 Cable C1

480V Emergency Switchgear

480V Emergency Switchgear

VLV

ZC1 480V Emergency Switchgear

VLV

Cable C2

Station Auxiliary LV Input Base Loads at 460V (Lump Loads except largest motor)

Fire Water Pump Motor 150kW, 460V (Largest Motor)

ZLV

ZC2

VMS

ZMS

SINGLE LINE DIAGRAM

152156824.xls.ms_office - SLD

EQUIVALENT CIRCUIT - 1 MOTOR PRE - START CONDITION

ZEL = ( ZC2 + ZMS ) II ZLV

ZLV

EQUIVALENT CIRCUIT - 2 MOTOR START CONDITION

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DG Sizing

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