startup guidelines for gtg

GTG (MS-5001-PA)

INITIAL START-UP PROCEDURE

AND GENERAL GUIDE LINES

Document No.O&U-12-OM-110

Revision 01

Date of issuance 02/08/2010

17.1 General indication

The scope of the following instructions is to put in condition the Operators to prepare the GTG Unit

and relevant auxiliary equipment, through the commissioning activities carried out in each system

involved, at initial start-up.

The operations are developed as follows:

- Commissioning of GTG train with the auxiliary equipment installed on the same base plate (as

starting system, fuel system on base, oil system, etc.)

- Commissioning of auxiliary equipment installed outside the baseplate and installed on the different

skids.

- Initial startup procedure

- Normal startup procedure.

Therefore will be available in the plant:

- AC and DC electric power, to supply all the electric and control/protection panels of the GT and

Generator.

- The instrument air for the required uses.

- Water for cooling the oil systems.

- The fuel gas for GT operation.

- The fire fighting system of the plant to protect the auxiliary skids.

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When the services before mentioned are available and the commissioning activities referred to all

systems involved in GTG operation are completed, the Operators may proceed with the initial start

activities.

17.2 PREPARATION FOR START-UP

17.2.1 General

The gas turbine MS5001PA is provided with automatic sequence for “start-up” and “shutdown” by

means of SPEEDTRONICTM Mark VI.

The aim of this paragraph is to briefly remind some of the activities involved in the initial start-up,

especially referring to all the preparation work to be carried out prior to initial operation.

Technical terms for distinguishing the different phases included in”Preparation for start-up” are:

· Pre-commissioning: including all preparatory work

· Commissioning: providing the start-up sequence of the units

The preparatory works includes:

· Systematic conformity checks, carried out on each item of equipment or component, visual

verification of the condition of equipment, the quality of the installation, compliance with project

drawings and specifications, manufacturer’s instruction, safety rules, codes, standards and good

construction practice.

· Completed equipment static/de-energized tests to ensure the quality of equipment installation

(”cold tests” – concerns all disciplines):

o Calibration of instruments

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o Testing and setting of pressure relief valves

o Machinery alignments

o Hydrostatic pressure testing of piping

o Testing of cables and electric equipments (insulation resistance, continuity, etc), functional

tests on all protection relays and interlocks.

· Cleaning and flushing of the unit (air blowing, oil flushing), dry all equipment.

· All initial fill of lubrication oil, grease, chemicals, etc. Commissioning of the units includes:

· Pre start-up activities such as:

o Dynamic tests: (electrical motors uncoupled runs, instrument loops tests, electrical breakers

operation, energisation of electrical distribution net-work)

o Mechanical preparation: (running-in and on line tests for a significant period of the utilities or

of the main process equipment in closed loop).

o Gas-in preparation: (piping drying out, leak tests, inert).

17.2.2 Introduction

The scope of the preparatory works to get the GTG plant started is:

1) Commissioning and put in service GTG Fire & Gas detection and protection System.

2) Commissioning and put in service Fire & Gas Detection System for Control Cabin (at least), if

any.

3) Commissioning and energize the MCC and all utilities needed for a normal operation of GTG,

such as:

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• AC & DC distribution system (MCC, UPS, etc.)

Commissioning and starting all the utilities for a gas turbine normal operation (oil systems, fuel gas,

ventilation systems, oil cooling system, GTG fire fighting system and etc.

17.3 Lube oil system

Valves position (opened/closed) for initial start-up and normal operation of lube oil system is

indicated in Schematic Piping Diagram.

The unit is equipped with one mechanical shaft-driven pump [9-P-12603X], an AC auxiliary pump

[9-P-12604X] and a DC emergency pump [9-P-12605X]. Their purpose is, to lubricate and cooling

the GT, as well as the gear box and generator, bearings during the unit operation.

The lube oil pumps are designed for continuous operation but are not operated after the gas turbine

package is shut down and the cool down timer has elapsed.

To operate the mineral lube oil pumps, the oil tank level and temperature shall be between the

operation limits; if the level (300÷400 mm. from tank top cover) or temperature (20°C÷79°C) is not

OK before starting, starting will be inhibited and an alarm will occur. If one of the parameters will

be not OK during operation of the unit an alarm and subsequently a shut down will occur.

Valves position (opened/closed) for initial start-up and normal operation of lube oil system is


Prior to start the gas turbine, the operator selects:”Auto” control in MCC for [9-H-12601XA/B/C/D]

lube oil heaters and [9-PM-12604X] auxiliary lube oil pump, and in DCP for [9-PM-12605X]

emergency lube oil pump.

When unit start is selected the lube oil system starts automatically.

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When the right pressure is restored permission to continue with starting sequence is given.

When the gas turbine reaches the ”OPERATING SPEED”, at 95% of the rated speed, the AC

auxiliary lube oil pump will be manually stopped and the accessory gear driven main lube oil pump

guarantees the oil flow amount.

As long as the gas turbine is above the ”OPERATING SPEED”, if the conditions ”LUBE OIL

HEADER PRESSURE LOW” (MK VI command name 4QA) will be detected, the AC auxiliary oil

pump will be automatically started. If normal conditions are restored, the stand by pump can be

stopped manually from the HMI or from the MCC according to the duty/standby philosophy.

The lube oil header pressure low-level threshold [63QT-2A ÷ 63QT-2C]/[PT-12618-A/B/C],

installed on the Generator lube oil header, causes the DC emergency lube oil pump to start if lube oil

header pressure is lower than the shutdown level.

With such threshold, when the emergency pump comes in operation, the unit is in shutdown

condition.

Once the pump is started, it runs continuously for 15 minutes and then 30 seconds on, 3 minutes off

cycle is started for power supply batteries safeguarding until the end of cool down. The DC

emergency lube oil pump will be stopped as soon as the condition”LUBE OIL HEADER

PRESSURE NORMAL” is detected [96QA-1 ÷3]/ [PT-12618-A/B/C].

During normal GT operation, the operator is normally allowed to manually start and stop the standby

pump, unless it is prevented to run or required on by the control logic.

17.4 Hydraulic oil system

Valves position (opened/closed) for initial start-up and normal operation of the hydraulic system is


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The Gas Turbine is equipped with one mechanical shaft-driven pump installed on the Accessory gear

box. Its purpose is to operate the axial compressor IGV nozzles and the GT gas valves. [SR V-1 and

GCV-1]/[FCV-12601 & FCV-12602].

The H.P oil pump is designed for continuous operation but is not operated after the gas turbine

package is shut down.

To operate the Hydraulic oil pump, the oil pressure shall be inside the operation limit; if the pressure

value is not OK (6500 kPaG min.) an alarm will occur. The maximal pressure admitted for the

hydraulic mechanical driven pump delivery is 9000 kPaG regulated by a overpressure valve [VR-

21]/ [PSV-12601]; and is also protected from overpressure by a pressure regulating valve [VPR3-1]/

[PCV-12610] inside the pump body that will be regulated at 8000 kPaG.

If the pressures decrease under the minimal pressure (6500 kPaG) during the Unit operation an

alarm is generated by a pressure switch [96HQ-1]/[PT-12614]

When the hydraulic oil pump driven by accessory gear box reaches the 1500 RPM it guarantees the

oil pressure and flow amount during gas turbine operation.

17.5 Lube oil mist separator

Valves position (opened/closed) for initial start-up and normal operation of oil vapor separator is


Prior to starting the GT operator selects”Auto” control in MCC for [9-CM-12605X] lube oil vapor

separator.

One of the two lube oil vapor separator fans [9-CM-12605X] (the selected one as main) will be

started at turbine start-up and will continue to operate up to the end of cool down sequence. The

stand-by one will be started, by intervention of differential pressure transmitters, in case of oil tank

pressure increasing over the rated limit. Set: Alarm 20 mm.H2O; Trip 50 mm.H2O.

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The fan will be started also in case of pressure detected in the lube oil tank after cool down end.

17.6 Fuel gas system (on base)

Prior to first gas-in, fuel gas system will be leak tested at normal operating pressure afterwards

followed by fuel gas system inerting using nitrogen (filling and purging until oxygen content at point

of supply to stop / ratio valve drops below 2%).

Required fuel gas supply pressure at point of supply to GTG must be between 1600 kPaG min. and

2400 kPaG max.

A”Fuel gas pressure low” alarm is given in the Mark VI software by the [96FG-1]/ [PT-12602-

A/B/C] pressure transmitter, when gas pressure drops to 1400 kPaG.

Required fuel gas temperature for normal running at point of supply to GTG will be 28°C above dew

point and in any case between 45°C and 60°C.

17.7 Cooling & sealing air system

The antisurge valves will be checked and will be open to be enable to start the Unit, the control of

opening of the valves will be verified by the signal transmitted by the positioning micro-switches

[33CB-1 and 33CB-2] sending a signal to the Control Panel.

Check the correct operation of the antisurge valves, before starting the turbine, using an external

source of air, to be able to open them by acting the relevant servovalve [20CB-1].

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17.8 Ventilation & gas detection system

The gas turbine compartment is equipped with 2×100% duty/standby ventilation fans [9-C-12608XA

and 9-C-12608XB].

Before proceeding to first start up of ventilation system operator ensures that all fire dampers for

ventilation air inlet and outlet are opened. Operation with fire dampers closed is not allowed.

The GT compartment ventilation fans are designed for continuous operation but are not operated

after the gas turbine package is shut down and cooldown timer has elapsed.

Prior to start the gas turbine, the operator selects: ”Main/Duty” for [9-C-12608XA] turbine enclosure

ventilation fan and ”Standby” for [9-C-12608XB] turbine enclosure ventilation fan, in Mark VI

software, and ”Auto” control in MCC for [9-C-12608XA and 9-C-12608XB] and for [9-HH-

12608XA; 9-HM-12608XB] of motors space heaters.

When unit start is selected, the duty fan is started automatically.

After the activation of ”MASTER PROTECT IVE SIGNAL” the fan is not stopped any more until

the end of cool down, unless emergency conditions such as fire dampers closed or fire detected in

the enclosure: in these cases all fans shall be immediately cut out.

Fans inhibition for fire dampers closed is not latched and once the dampers are open again the fans

are no more prevented to run.

If there are conditions as”Compartment temperature high” or”Gas detected in-side enclosure”, the

stand by fan automatically starts. If normal conditions are re-stored, the duty fan can be stopped

manually from the HMI or from MCC according to the duty/standby philosophy.

During normal GT operation, the operator is never allowed to manually stop the duty fan.

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The operator is normally allowed to manually start and stop the standby fan, unless it is prevented to

run or required on by the control logic.

The operator is allowed to initiate any time a duty/standby changeover: the selection is performed by

means of the MK VI <HMI> operator interface software pushbutton.

17.9 Starting system

A visual inspection of the turbine should be performed before attempting to operate the GTG.

Prior to starting the gas turbine, the operator will close the switch of [9-PD-12606X] starting motor

in MCC.

Before starting will be selected the mode of GTG operation putting the Main Selector in required

condition (CRANK, FIRE, MANUAL, AUTO, and RE-MOTE).

Will be checked the correct operation of the [33CS-1] (starting clutch limit switch).

17.10 GT Fire detection & fighting system

Valves position (opened/closed) and instruments condition for initial start-up and normal operation

of fire fighting system is indicated in Schematic Piping Diagram.

The two banks of CO2 bottles (main and spare) are operated by the Turbine Control System.

The condition “ready to start” will be given by the limit switches [33CP-1A/B] positioned on the

quick and slow discharge valves installed on the CO2 line to the turbine enclosure.

In case of fire the sensors installed on the accessory compartment [45FA-1/2] [45FT -1÷4] fire

detectors; on the turbine compartment fire detectors and/or [45FT-5/6] heat detectors send fire

signals to UCP and this one generate a CO2 discharge command.

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There are in the system two discharge solenoid valves operating the different groups of CO2 bottles

(for quick discharge and for slow discharge). When the fire is detected the valves [45CR-1/2] in

bank “A” (main bank) e energized opening the quick discharge group and consequently also the

slow discharge flow.

When is detected the fire signal are activated two alarms signal on the acoustic enclosure, through

the horns [XA-1÷2] as acoustic signal and through the flashing lights [XL-1÷2] as a visual signal.

The UCP fire fighting system is provided with two “Fire fighting auto-inhibit switch” [33CP-1A and

33CP-2Ato inhibit the discharge phase of CO2 for permission to start-up. Every inhibit signals from

the fire fighting system send an alarm to the UCP inhibiting the turbine start-up.

The start-up of the turbine will be also inhibited when the signal “System fault” (66XX-A/B) send

an alarm to the UCP.

The “Discharge inhibition” on the fire fighting system is signaled by a green lamp, lighted with the

system in AUTO mode and with an amber light when the discharge is inhibited. But the inhibition is

actuated for CO2 discharge only, while the detection modules with the relevant indications are

operating.

17.11 Generator

Valves position (opened/closed) for initial start-up and normal operation of lube oil system of

Generator is indicated in Schematic Piping Diagram.

Prior to starting the gas turbine, the operator shall check the correct oil supply pressure to the

generator bearings by the pressure indicators on the oil header, on the bearings inlet piping DE and

NDE side respectively. Will be checked also the oil flowing through the discharge oil piping flow

gauges (FG12632X; FG12633X).

The operator will check on the vibration monitor, Generator section, and the correct readings of

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vibration sensors, the key-phasor values and the bearings temperature elements, to verify the correct

operation.

Will be checked also the stator winding cooling thermo elements readings for correct operation.

17.12 Load Gear Box

Valves position (opened/closed) for initial start-up and normal operation of lube oil system of Gear

Box is indicated in Schematic Piping Diagram.

Prior to starting the GTG, the operator shall check the correct oil supply pressure to the Gear Box

bearings by the pressure indicator on the oil header and the oil flowing through the bearings

discharge oil piping flow gauge (FG12631X).

Furthermore will be checked on the vibration monitor, gear box section, the correct axial positioning

of the shaft and the readings of vibration sensors and the bearings temperature elements, to verify the

correct operation.

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17.13 PROCEDURE OF START-UP

Checks Prior to Start-Up

Gas Turbine checks

A visual inspection of the turbine should be performed before attempting to operate a new turbine,

with the lube oil pump operating and emphasis on the following areas:

1) Check that all piping and turbine connections are securely fastened and that all blinds have been

removed.

2) Inlet and exhaust plenums and associated ducting are clean and rid of all foreign objects. All

access doors are secure.

3) Where fuel, air or lube oil filters have been replaced check that all covers are intact and tight.

4) Verify that the lube oil tank is within the operating level and if the tank has been drained that

it has been refilled with recommended quality and quantity of lube oil. If lube oil flushing has been

conducted verify that all filters have been replaced and any blinds if used, removed.

5) Check operation of auxiliary and emergency equipment, such as lube oil pumps, etc. Check for

obvious leakage, abnormal vibration, noise, or over-heating.

6) Check lube oil piping for obvious leakage. Also using provided oil flow sights; check visually

that oil is flowing from the bearing drains. The turbine should not be started unless flow is visible at

each flow sight.

7) Check condition of all thermocouples and/or resistance temperature detectors. Reading should be

approximately ambient temperature.

8) Device requiring manual lubrication is to be properly serviced.

9) Check the Cooling and Sealing Air Piping against the assembly drawing and piping schematic,

that all orifice plates between flanges or in orifice unions are of designated size and in designated

positions.

10) At this time all enunciated ground faults should be cleared. It is recommended that units not be

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operated when a ground fault is indicated. Immediate action should be taken to locate all grounds

and correct the problems.

Generator/Gear Box checks

1) With turbine oil pumps running check the oil flushing through the generator bearings and the

load gear box.

2) Excitation system in operation

3) Protection system in operation.

General checks by HMI Video Display

The most important controls to be made to verify the GTG conditions in real time, during startup or

operating sequences, should be executed by the HMI video display.

Checks during Start-Up and Initial Operation

The following checks must be done on a GTG, these checks should include: leakage test, vibration

unusual noise, overheating, and lubrication.

Listen to noise

Start turbine and stop it at around 600 rpm.

Listen for rubbing noises in the turbine compartment, load gear and genera tor.

A sound scope or some other listening type device is suggested.

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Crank

1. Listen for rubbing noises in the turbine compartment, load gear and generator.

2. A sound scope or some other listening type device is suggested. Shutdown and investigate if

unusual noise occurs.

3. Check for unusual vibration

4. Inspect for oil leakage.

Fire

1. Check entire fuel system and the area immediately around the fuel nozzle for leaks. In

particular check for leaks at the following points:

a. Fuel oil piping/tubing to fuel nozzle

b. Fuel gas valves

c. Gas piping to the burner.

2. Monitor the turbine control panel readings for unusual exhaust thermocouple temperature,

wheel-space temperature, lube oil drain temperature, highest to lowest exhaust temperature spreads

and ”hot spots”, combustion chamber burning hotter than all others.

3. Listen for unusual noises and rubbing.

4. Monitor for excessive vibration

Manual, Automatic, Remote

1. Continue monitoring for unusual rubbing noises and shutdown immediately

if a noise persists.

2. Monitor lube oil tank, header, white metal bearing and bearing drain temperatures continually

during the starting period.

3. At this time a thorough vibration check is recommended, using portable vibration test equipment

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with filtered and unfiltered readings.

It is suggested that horizontal, vertical and axial data be recorded for the:

a) Accessory gear forward and after sides.

b) All accessible bearing covers on the turbine.

c) Turbine forward compressor casing.

d) Turbine support legs.

e) Covers on the driven Units.

4. Check and record wheel space, exhaust and control thermocouples for proper indication on the

control display.

5. Check and record electrical characteristics of generator.

6. Monitor control display data for proper operation.

17.14 Gas Turbine Start-up & Operation

Introduction

The mode of operation for GTG is:

· OFF

· CRANK

· FIRE

· MANUAL

· AUTO

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· REMOTE

General

The GT Unit Control Panel is equipped with two HMI: one (local) in the Main Sub Station Building,

for controlling purposes, and the other (remote) in the Central Control Room(CCR-I) for monitoring

purposes, as normal options.

Once the main HMI fails, the controlling functionality of the second HMI is enabled and the

operator can continue to control the unit.

Modes of operation and sequences

There are six operating modes varying from no start acceptance to full automatic start. Only one

mode can be active selecting one mode (position) of MASTER SELECTOR means disabling all the

other modes.

The mode selection can be performed at the local MKVI HMI (PC operator inter-face) and at the

operator back-up panel mounted in the front of the Mark VI panel. The back-up feature is required to

give the operator the ability to control the unit (basic function as START, STOP) in case of a failure

of the MKVI HMI or loss of customer UPS power supply.

Mode selection can be used to bring in some hold points in the start sequence and to monitor the

process at these stages.

a) O f f Mode

When the OFF Mode is selected, the UCP does not accept the START command, and is thus not

possible to start-up the machine. All other functions remain active.

Auxiliaries’ manual control is possible, if the relevant safeties are satisfied.

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It shall not be possible to select and initiate the OFF Mode when the GTG is running or the

COOLDOWN sequence is still in progress.

b) Crank Mode

CRANK sequence may only be selected after the gas turbine has stopped rotating.

Starting the turbine with this selection is possible if the unit start permissive is satisfied.

Starting the turbine with this selection will bring the shaft up to crank/purge speed value of 20%

(14HM).

Sequence will precede changing Master Selector position to FIRE, MANUAL, AUTO, or REMOTE

position. The shaft will continue to rotate at 20% of speed value until the operator initiates a normal

STOP, changes the Master Selector position or a shutdown occurs. Gas turbine shaft can remain at

this speed indefinitely if the operator will not select another command.

For OFF-LINE WATER WASH the selection of CRANK mode is mandatory, and as long as the

wash cycle is enabled the CRANK mode will be locked.

c) Fire Mode

This mode of operation shall primarily be used to verify that the GT start sequence functions

properly.

Once the start permissive are valid/healthy, the operator may initiate start.

The turbine will continue to run at warm-up speed, unless the operator selects another operation

mode or initiates a normal stop or shutdown.

By subsequently selecting MANUAL, AUTO or REMOTE Mode, start-up sequence is executed to

accelerate the shaft of the turbine to the preselected speed.

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d) Standard Manual Mode

In the MANUAL Mode a start signal will result in an automatic start-up and loading to the minimum

operating speed, then the shaft speed is controlled by raise and lower commands on HMI.

e) Auto Mode

In the AUTO Mode a start signal will result in an automatic start-up and loading to the selected

value, an external signal from DCS is taken as shaft speed set point.

f) Remote Mode

In REMOTE Mode position, the set point of load may be varied from outside through the commands

from DCS. The increase and decrease variation speed of the turbine shaft depends on the value

imposed by the automatic ramp and can be modified through the Operator Interface.

Start-up sequence – AUTO / REMOTE mode

AUTO or REMOTE Mode enables initiation of the complete start sequence, up to the pre-selected

speed of turbine shaft.

a) Prior to start-up permissive must be confirmed; these will include:

· No other modes selected and/or other sequences initiated and/or in progress (except lube oil

pump or enclosure fans post-run sequences)

· Package off mode not selected

· GT speed = 0 RPM

· Package shutdown push buttons reset

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· Fuel control valves (SRV and GCV) in correct position (closed)

· Fuel gas vent valve 20VG-1 in correct position (check status of output relay)

· Fuel gas supply pressure above minimum

· Package enclosure doors closed

· Fire dampers open

· Fire alarm cleared

· CO2CO2 system not in fault

· Battery voltage from DCP above minimum

· Emergency lube oil pump ”Ready to start”

· MCC ”Ready to start”

· All parameters that are monitored for alarm and trip purposes are in the healthy state for start-

up (lube oil tank has the correct oil level and temperature, etc.)

· All trip identified in P&I diagrams are cleared

· Fuel gas inlet pressure not low (63FG- 1)

b) When the Shut Down reset and Ready to start – check condition as per (Control system

functional description) are satisfied, the message ”UNIT READY TO START” will be shown on the

MK VI<HMI> operator interface display.

c) The ”START” command can be initiated by the software pushbutton on MK VI<HMI> and the

following actions will be initiated:

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d) Start automatically the Gas Turbine Lube Oil auxiliary pump [9-PM-1 2604X]. When the lube

oil header pressure is restored, the lube oil system is considered ready for operation.

e) Start automatically the Lube Oil main Separator fan [9-CM-12605X]

f) Start automatically the Gas Turbine main ventilation fan [9-CM-12608XA]. The compartment

is equipped with 2×100% ventilation fans. Automatic start of standby fan for the GTG is initiated by

high temperature and/or high gas concentration and/or main fan failure.

g) ”UNIT READY TO START” condition is achieved and if no shutdown condition is present

(the”MASTER PROTECTIVE RELAY (4x)” is still activated), the MK VI logic will give the

command to start the starting motor.

h) The motor starts (4CR) is energized

i) The turbine will accelerate up to crank speed (20% of shaft speed value – 14HM).

j) Start the turbine purge phase (approximately 2 minutes, to be configured in field) to purge the

turbine, combustion air inlet and exhaust systems, and wait for purge completion.

k) Open the fuel gas vent valve [20VG-1] and when the fuel gas temperature reaches the set

threshold, the fuel gas vent valve [20VG- 1] will be closed.

l) Completed the purge time, is energized the ignition (L2TVX).

m) MKVI will check for excessive fuel flow, if that condition is detected a trip is initiated.

n) Allow a maximum of 1 minute for light off; activate ”fail to ignite alarm” if flame is not

detected within 2 minutes and continue to rotate at crank speed.

o) The fuel amount is reduced and the warm-up timer is started.

p) At the end of warm-up period (1 minute), the torque converter raises output torque unless ”Fire

mode” is selected; in this case the turbine shaft will continue to rotate at warm-up, more than 20%

speed.

q) The torque converter is accelerated and fuel is increased to reach the mini-mum operating

speed; during the acceleration sequence, when the turbine shaft reaches the 60% speed (14HC), the

clutch will automatically disconnected. The starting system decelerating up to minimum speed, the

starting system is stopped five minutes later (cooling time).

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r) At 90% speed of the shaft (14HSX), minimum operative speed, the lube oil auxiliary pump [9-

PM-12604X] – (4QA) will receive a command to stop. The generator excitation is enabled.

s) When the turbine shaft reaches 95% of speed (14HS-1) will be closed the axial compressor

bleed valve and the complete sequence flag will be set.

t) After completing the Start up sequence, are enabled the speed set-point variation and the

turbine is ready to synchronize.

Activities on Generator

The following operating activities are only suggested.

Reached the complete sequence of the turbine shaft, and before synchronizing the Generator with the

network, it will be possible to perform the Generator checks, as follows:

a) Short circuit checking at Generator terminals.

b) After exciting the Generator at required current, check the stator current measuring circuits.

c) Check, for each protection branch, the differential current protection, following the noting

the trip value.

d) Check the unbalance protection increasing the stator current and noting the trip value.

e) Check the rotor earth protection increasing the current excitation at the required value.

f) Test of overload protection

g) After the no load test check the Min. and Max. Voltage protections.

h) With Generator at the rated voltage, check the frequency protection.

i) Testing of the power protection (power return, excitation loss, etc.).

j) Before proceeding with the synchronization check:

- The synchronoscope 0,

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- The differential voltage 0,

- The frequency at the coupling switches closing on an out of voltage network.

Synchronization sequences

At minimum operating speed excitation control will be enabled. The Mark VI checks the

synchronization permissive conditions and the speed reference is set at 100.3%. When 100.3% is

reached “Unit ready to synchronize” is displayed.

The operator has the opportunity to select in the Mark VI<HMI> “Synchronization Mode Selector”

the following mode: off, manual, automatic or dead bus.

a) Off mode

Disable all the Mark VI synchronizing functions.

b) Manual mode

The synchronization will be made in manual mode. The panel will send the raise/lower commands

signals to excitation panel for the voltage regulation. When the unit is synchronized, the operator

will close the breaker from the HMI.

c) Auto mode

The Mark VI will adjust the speed and voltage, and will issue the command for breaker closure when

unit is synchronized.

d) Dead bus mode

For this mode, the breaker is closed before to close contactor on ECP. This will avoid high inrush

current due to energization of transformer.

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As soon as the breaker is closed, the closing command to excitation contactor on ECP is given and

the generator rise on voltage and energize transformers. Once the rated voltage is reached the UCP

can start to load the machine.

Load control

Droop or isochronous control is selected on HMI.

Droop mode

When the GTG unit is connected in parallel to the main grid, the system frequency is determinate by

the grid itself and is maintained constant. The excess of fuel flow does not result in speed variation,

but in augmentation of power ex-ported to the grid.

The operator can enter a certain MW value as a load control constant. When pre-selected load is

selected the unit will automatically load or unload till the required value.

The selected mode of control (spinning reserve, preselected) will be reset to manual control when the

operator uses the raise/lower commands on HMI or when the governor control is transferred from

droop to isochronous.

The VAR control is based upon the use of voltage raise and lower signals to ECP.

Isochronous

The unit is controlled to maintain a constant speed, regardless of the grid load re-quest and

regardless of the supplier power. When the unit is in this mode, it is not possible to set a supplied

power set point.

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startup guidelines for gtg

Documents

commissioning activities

condition of equipment

initial operation

startup sequence

item of equipment

pa initial startup procedure

relevant auxiliary equipment

pre startup activities