dc supply system for thermal power plant.ppt

8/13/2019 DC Supply System for Thermal Power Plant.ppt

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25 December 2013 PMI Revision 00 1

DC SupplySystem


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Duties

DC Loads

DC system

Types of Batteries

Presentation outline


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DC SYSTEM ISDESIGNED TO SUPPLY HIGH STANDARD OF RELIABLE &

SECURE DC POWER

TO PROVIDE CONTINUOUS & QUALITYPOWER AS AND WHEN REQUIRED

UNDER NORMAL & ABNORMAL OPERATINGCONDITIONS

ULTIMATE & FINAL DC BACK-UP POWER TOEQUIPMENT AND DC DRIVES WHEN TOTAL ACSUPPLY FAILS

HENCE THEY ARE BATTERY BACKED


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DUTIES TO SUPPLY EQUIPMENT WHICH REQUIRES DC

DURING NORMAL CONDITIONS

TO SUPPLY STANDBY EQUIPMENT/DC DRIVES

TO SUPPLY STARTERS OF VARIOUSEQUIPMENT

TO SUPPLY EQUIPMENT WHEN AC SUPPLIESHAVE BEEN LOST


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Types of Power SuppliesIn a Power Plant 11KV/3.3KV/415V AC Power Supply

415V AC Emergency Supply(DG)

DC Power Supply

UPS Supply


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DC Power Supply Various Critical Drives

Emergency DC Lighting

Switchgear Control Supply for closing & tripping

Control, Protection And Interlocks

Indication, Annunciation & Alarm System

Public Address System

DAS And Communication System


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DC SuppliesWhy Emergency Lube Oil Pump

Emergency Jacking Oil Pump

Emergency Scanner Air Fan

Emergency Seal Oil Pump

Breaker/Unit Protections

Emergency Lighting


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The Ultimate BackupIn case of unit tripping / grid failure, either station

changeover takes place / DG would start.

Normally, grid supply would be restored in minimum

possible time and DG would shut down.

In case of DG failure, the DC backup comes in to

service to facilitate safe shut down.


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Selection of voltage -DCPOWER SUPPLY In power plant D.C. pumps, lighting require comparatively

high voltage due to their high power requirement. Hence asa standard these applications are designed with 220V level.

It is desirable to have comparatively lower voltage-24V/48V/110V for control/indications/annunciation due tosafety reasons. However to avoid multiplicity of DC supplies(particularly we require two control supplies), we haveadopted uniform 220V DC voltage for plant electricalsystems for switchgear control, protection and interlockoperation.


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DC System Battery

Battery Charger


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220 V DC SYSTEM

Charger I

440 V

220 V DC

Charger II

Battery

Bank

Battery

Bank

Feeders

440 V

220 V DC

Feeders

DCDB


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X X

X X

X XX X

DG-1DG-3

DG-2

DG SWGR-1DG SWGR-2

UNIT EMER

SWGR-1UNIT EMER

SWGR-2

UNIT EMER

SWGR-3

UNIT EMER

SWGR-4


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EMCC(1) AOP-1 (2) Em. Lighting Trf.

(3) TVDC Reserve Supply (4) UPS Ch.

(5) Scanner Air Fan (6) BVDC Reserve Supply

(7) AC Seal Oil Pump (8) Air Heater Lub Oil Panel

(9) Jacking Oil Pump (10) Stator Water Pump-B

(11) Barring Gear (12) +26 V DC ATRS Ch. B(13) -26V DC ATRS Ch.B(14) 26V DC FSSS Ch. B

(15) 26V DC DDC Ch. A


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220 V DC FSSS

HT Breakers Vacuum Breakers

HOTV/HORV

Deaerator Overflow Valve

GRP HP Heater Protections

DC Fans & Pumps

Extraction FCNRV V/Vs

SADC

Trim Device

Load Shedding Relay

Scanner Air Fan Outlet & Emergency Damper

All DC Lights


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25 December 2013 19

/- 24 V DC System

+/-24 V

CHARGER-

A

+/-24 V

CHARGER-B

Batteries

350AH

Batteries3

50AH

EMCC

USS


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25 December 2013 20

/- 24 V DC System+24 V DC - 24 VDC

EHC LPBP

ATRS PANNEL SPEEDER GEAR/STARTING DEVICE

ALL TURBINE PROTECTIONS EHC

LPBP ATT

TSE ACS CABIN

STARTING DEVICE TSE

LUB OIL TEMP/CONTROL FLUID TEMP/MAL

TEMP/COLD GAS TEMP

LUB OIL TEMP/CONTROL FLUID

TEMP/MAL TEMP/COLD GAS TEMP

EXCITATION SYSTEM CARDS AVR

JOP-3 GRP

LOAD SHEDDING SOLENOID


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25 December 2013 21

Battery


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Applicable Standards Lead Acid Plante BatteriesIS:1652

Vented Ni-Cd BatteriesIS:10918, IEC:60623


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Manufacturers In IndiaLead Acid Plante

Batteries

Exide Industries

Ni-Cd Pocket Plate

Batteries

AMCO Batteries

HBL NIFE Batteries


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Battery Capacity Expressed in ampere hour(AH)

Duration of discharge-10 hr for Plante/5 hr for Ni-

Cd

End cell voltage-1.85 volt for Lead acid plante/1.0

volt for Ni-Cd

Ambient temperature-27 deg cent.

Electrolyte specific gravity-1.2+-.005 lead acidplante cells


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SELECTION OF BATTERYTYPE IN POWER PLANT Power plant batteries standby duty require high discharge

performance with continuously connected on float mode operation.

Expected Life of lead acid tubular is of the order of 8-10 years so in

a power plant life of 25 years minimum two replacement would be

required.

Lead acid PLANTE and Ni-Cd (alkaline) have expected life of 15-20years hence only one replacement would be required in whole plant

life.

In addition lead acid plante have much better discharge

performance than tubular type for the specified emergency duration.

In view of above plante type lead acid or Ni-Cd high dischargebatteries are specified for power plant applications.

Wherever there is space constraints VRLA batteries may be an

option however this has also expected life of 8-10 years.


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dc supply system for thermal power plant.ppt

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