black start

BLACK START

Zujajah Masud

U.E.T Lahore

INTRODUCTION

• Restoration of an electric power station or a part of an electric grid to operation without relying on the external transmission network

• To recover from a total or partial shutdown of the transmission system which has caused an extensive loss of supplies

• To provide a black start, some power stations have small diesel generators, normally called the black start diesel generator (BSDG)

EPQL PLANT OVERVIEW• 1+1+1 combined cycle configuration

• produces approximately 217.3 MW utilizing “Permeate Gas” as primary fuel whereas HSD is available as backup fuel.

• one frame 9E gas turbine of 112 MW

• one steam turbine of 110 MW

• auxiliary firing is employed in HRSG.

BLACK START SOURCE

• Two black start diesel generators, each of 1.5 MW

• One emergency diesel generator of 800 kW

• BSDGs will be used to start up gas turbine

• Start up of steam turbine during black start uneconomical

• Steam turbines require station service power of up to 10% of their capacity for boiler feed water pumps, boiler forced-draft combustion air blowers, and for fuel preparation

START-UP SEQUENCE• Emergency DEG is

started and power is supplied to GT MCC

START-UP SEQUENCE• Black start DEGs are

started and power is supplied to 11 kV bus bar-A

• 415 V bus bar-I and III are energized respectively

START-UP SEQUENCELoad during start up

415 Bus bar

Feeders 1 and 3

industry water pump 75 kW

BMS cooling fan 9 kW

air compressor 75 kW

product water pump 18.5 kW

GT cooling water pump 37 kW

GT close circle water pump kW

LP feed water pump 30 kW

GT HSD pump 37 kW

281.5 kW

START-UP SEQUENCE

• GT start motor is started

• Inrush current 5 to 6 times of rated value

• Inrush current is limited by soft starter

START-UP SEQUENCE• Peak value of current: 194 A

• Load of GT start motor during inrush current period is 2.122 MW

415 Bus bar Feeders 1 and 3

GT start motor(inrush current period) 2112 kWindustry water pump 75 kWBMS cooling fan 9 kWair compressor 75 kWproduct water pump 18.5 kWGT cooling water pump 37 kWGT close circle water pump kWLP feed water pump 30 kWGT HSD pump 37 kW

Total Transient Load at time of startup 2393.5 kW

START-UP SEQUENCELoad during inrush current period

415 Bus bar Feeders 1 and 3

GT start motor 1000 kWindustry water pump 75 kWBMS cooling fan 9 kWair compressor 75 kWproduct water pump 18.5 kWGT cooling water pump 37 kWGT close circle water pump kWLP feed water pump 30 kWGT HSD pump 37 kW

1281.5 kW

START-UP SEQUENCELoad after GT start motor has started

START-UP SEQUENCE

• GT start motor is stopped after GT speed reaches 60%

• When GT reaches FSNL, insulation switch J1Q30 is closed manually and GT GCB J1Q1 is closed via MKVI

START-UP SEQUENCE• When GT

generator voltage increases to rated value, “Isochronus” target is selected in MKVI and main transformer T-1 HV isolator and breaker are closed

START-UP SEQUENCE• Main transformer

T-2 HV isolator and breaker are closed

• Auxiliary transformer TR-12 is energized

START-UP SEQUENCE• Auxiliary

transformer TR-12 LV breaker is closed to energize 11 kV bus bar-B

START-UP SEQUENCE• Energize 415 V bus bar-

II and IV respectively

• Energize 415 V bus bar-I

• Change over load from 11 kV bus bar-A to bus bar-B

• Black start DEG is stopped

START-UP SEQUENCE• 11 kV bus bar-A

inlet switch is closed and 11 kV bus bar quick change over system operates

START-UP SEQUENCE• Change over load

from 415 V bus bar-V to bus bar-III

• Emergency DEG is stopped

START-UP SEQUENCE• Isolators D1Q31

and D1Q32 are closed and outlet breaker D1Q3 are closed

• GT is shut down

• Plant is restarted normally

MAXIMUM LOAD ON BSDG

• Maximum load is on black start DEG when GT start motor draws in rush current

• Total transient load at black start DEG during startup is 2393.5 kW

MAXIMUM LOAD ON EMERGENCY DEG

• Load on emergency DEG is of GT MCC which is:

GT MCC

AC lube oil pump 90kWTurning gear motor 30kWHydraulic Oil Pump 15kWL.O. tank fume extractor 18.5kWAir atomizing pump 15kWGT building exhaust cooling fan 45kWJacking oil pump 16.4 kW

229.9kW

RECOMMENDATION

• Presently, the entire black start up process is manual that is the sequential shuffling of load, closing of isolators and breakers

• It should be automated using PLCs

THANKYOU!