Instruction Control System

7/28/2019 Instruction Control System

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Instruction of Control and Safety System

1. Summary

Type N30-8.83/535 condensing turbine is a new developed unit, its

control and safety system adopts digital electro-hydraulic governor (DEH)

which consists of DEH controller, electro-hydraulic transducer, high

pressure oil relay, safety control box, emergency governor sliding valve,

etc. Details of system refer to Drawing of Control and Safety System.

Type N30-8.83/535 condensing turbine is designed to work under normal

steam condition. Under design condition, DEH controller regulates electric

load and speed of unit to meet the demand for electric energy. Besides

that, DEH controller receives signals of speed, power, main steam

pressure and pressure after velocity-compounded stage so as to control

and protect the unit. Mechanical, manual and electric safety system shall

be adopted to ensure safe and reliable operation. If abnormal condition

occurs, the control and safety system shall shut off main stop valve and

regulating valve to realize shutdown of unit immediately.

2Oil pressure of control system

Oil pressure of control system1.96MPa

Inlet oil pressure of oil pump0.1MPa

Impulse oil pressure0.98MPa

3Electro-hydraulic control system

3.1Principle

Controlling signals of speed and power shall be input to electro-hydraulic

control system (DEH system), then the synthetic signal shall be output


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from DEH controller to control electro-hydraulic transducer, and the

electrical signal shall be converted into pressure oil signal to control

opening degree of high pressure oil relay. So steam intake quantity of

regulating valve can be controlled to meet the demand for electric energy.

3.2 Technical parameters

Speed control range203600r/minAccuracy 1r/min

Load control range0115 Rated loadAccuracy 0.5

Speed diversity ratio 4.5 (36 adjusted)

System dead-band less than 0.2

During power of steam turbine changing from rated power to load rejected,

the maximum change of turbine speed shall be less than 9% of rated

speed.

Average continuous operation time without accident of DEH system:

MTBF>25000 hours

Available rate of system shall be 99.9%.

3.3 Function of DEH control system

3.3.1 Turbine replacementreset emergency governor and open stop

valve

A startup valve shall be adopted in control system to reset emergency

governor and open stop valve. After system resets, main stop valve shall

open automatically to control regulating valve.

3.3.2 Manual Operation/Semi-Auto/Programmed Control

Manual Operation


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Manually operate startup valve to reset emergency governor and open

main stop valve, then raise/lower the speed and load of steam turbine by

operating DEH system in manual.

Semi-auto

After opening main stop valve in manual operation, the operator shall

confirm target speed, raising speed rate, warming time, target load and

raising load rate.

Programmed Control

After opening main stop valve in manual operation, programmed control

starting shall be done according to the best operating curve input to DEH

control system beforehand. During the starting, all the motion shall be

done automatically without manual operation. The operator can switch the

mode of starting to the above two easily. Running curve can be modified

online.

3.3.3 Friction inspection

DEH control system shall control the speed raised/lowered within the

range 500r/min to inspect working and installation condition of steam

turbine.

3.3.4 Overs peed test

Under control of DEH system, 103% overspeed test, 110% overspeed

test and mechanism overspeed test can be done.3.3.5 AS

DEH control system has interface with AS device, and can receive

impulse signal output from AS device. After receiving signal from AS

device, the steam turbine speed shall be adjusted to achieve grid

frequency speed rapidly in order to realize synchronize with grid.


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3.3.6 After synchronizing with grid, DEH control system shall take (2

3)% initial load in order to avoid the running of reverse power.

3.3.7 DEH system can adjust electric load automatically according to

target value and load change rate confirmed by operator.

3.3.8 Control and limit of main steam pressure

DEH system has main steam pressure control function which can

compensate and control main steam pressure, namely control main

steam pressure through losing power.

3.3.9. Low vacuum protection

3.3.10. System can cooperate with CCS system and accept controlling

instruction from AGC.

3.3.11. Failure diagnosis and alarm

Failure diagnosis of DEH system can achieve channel level, for each

failure point DEH system shall give an alarm show on CRT.

3.3.12. The communication with DCS can be realized. The information

required by DCS can be supplied.

DEH system shall communicate with DCS by serial ports. The

communication agreement shall be coordinated between DEH system

and DCS system.

3.3.13. The modification and configuration of parameters can be done at

working station.3.3.14. Function of monitoring on operation

4. Safety system

4.1. Under the following condition, safety system shall cut off initial steam

supplying.


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When speed is 111%112% of rated speed (3000r/min), namely 3300

r/min3360r/min, emergency governor shall act, main stop valve and

regulating valve shall be shut off to realize unit shutdown.

When axial displacement of turbine is more than 1.2mm, lubricate oil

pressure drops to 0.02MPa, speed rises to 3360r/min and above

(can be adjusted according to user demand), vacuum drops to

0.06MPa, oil temperature of supporting bearing is 75, DEH control

system shall output signal of shutdown and make electromagnetic

trip device(in safety control box) act,the safety oil shall be

discharged and main stop valve be shut off. At the same time, the

impulse oil shall be discharged by emergency relay of

electro-hydraulic controller, high oil-relay shall act to shut off steam

valve to realize shutdown of unit.

Action signal from electromagnetic trip device (in safety control box)

shall be input to DEH system at the same time to shut off regulating

valve.

Pressure controller has function of low lubricate oil pressure protection.

When lubricate oil pressure is less than 0.055MPa, AC electric lubricate

oil pump shall be started; when lube pressure is less than 0.04MPa, DC

electric lube pump shall be started; when lube pressure is less than

0.015MPa, turning gear shall be stopped.

The manual emergency shutdown device (electromagnetic trip device)

shall be installed on faceplate of safety control box. When needing

emergency shutdown in manual, press the button to make sliding valve

move down, then realize shutdown of unit.Besides that, DEH system also

has function of OPC protection and overspeed shutdown.


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4.2. Structure of safety system parts

Emergency governor

The shell of governor shall be connected with front end of rotor directly.

Under condition of rated speed, the centrifugal force on fly-ball is smaller

than the stress of spring, and the fly-ball can not fly out. When speed is

111%112% of rated sped, the centrifugal force on fly-ball is larger than

the stress of spring, the fly-ball shall fly out suddenly and the travel is

6mm. The fly-ball shall strike the lever of emergency governor to makesafety system act, and main stop valve and regulating valve shall be shut

off promptly; When speed drops to near 3000r/min, the stress of spring is

larger than the centrifugal force again, and the fly-ball shall draw back into

the shell and be reset due to the stress of spring.

The action speed of each fly-ball of emergency governor can be adjusted

by adjusting nuts separately. When adjusting nuts clockwise rotate 30,

the action speed of fly-balls shall raise about 105r/min.

Under condition of normal speed3000r/min, the two fly-balls can act

separately through oil ejector. The oil from ejector nozzle shall enter into

the bottom of the fly-balls through oil chamber (K), the fly-balls shall be

pushed out by centrifugal force produced from the bottom rotating oil.

After oil ejecting stops, the oil shall flow out from the little holes at the

bottom of the shell. The fly-balls shall back to the initial position.

Emergency governor sliding valve

The unit mainly consists of sliding valve, sleeve, heart shaft, shell and

spring, etc.

During operating, emergency governor sliding valve is at the position of


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upper supporting point, chamber A shall connect to discharge oil through

groove hole on heart shaft, so there is no pressure.When the fly-balls

acting, the fly-balls shall strike the lever of emergency governor, then the

lever act to make the heart shaft move down, the pressure oil in chamber

B shall enter into chamber A through the heart shaft so as to enlarge the

area of oil pressure on upper of sliding valve. The force of oil pressure

acting upon the sliding valve shall be larger than that of annex safety oil

pressure under the sliding valve, so the sliding valve drops down. When

annex safety oil pressure drops below 0.96MPa, the sliding valve shall

drop to the lower supporting point, then the safety oil under sliding valve

of automatic shutoff device shall connect to discharge oil, the main stop

valve and regulating valve shall be shutoff immediately to cut off steam

intake.

Operate shutdown button, the annex safety oil under the sliding valve

shall be discharged. The sliding valve shall drop to lower supporting point

due to pressure oil of chamber B, and then the main stop valve and

regulating valve shall be shut off immediately.

Emergency governor sliding valve consists of two sets of valve and

sleeve with the same structure parallel connecting with each other.The

impulse oil pipelines of automatic shutoff device controlled by emergency

governor sliding valve also is parallel connection. So if any sliding valveacts, the main stop valve and regulating valve shall be shut off

immediately to ensure reliability of safety system.

Safety control boxPractical structure refers to Drawing of Control and Safety System and

drawings of relevant units.


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Safety and control box mainly consists of trip sliding valve, overspeed test

sliding valve, pilot valve, sliding valve of oil ejecting test of1, 2

fly-balls and small valves.

Besides that, electromagnetic trip device shall be adopted in system.

When the shutdown button is pressed in manual or the electromagnet is

power on, the sliding valve shall move down and annex safety oil shall

connect to discharge oil, then the oil pressure drops and main stop valve,

regulating valve and rotating diaphragm shall be shut off immediately by

emergency governor sliding valve.

4.3 Safety system test

Oil ejecting test of emergency governor fly-balls

The method of oil ejecting test of the two fly-balls shall be the same. Now

give an example of oil ejecting test of1 fly-ball. First rotate the pilot

valve from normal position to

1 position (anticlockwise rotating), thenthe oil mouth F1 shall open to D1, the pressure oil in chamber M1 shall

enter into oil chamber D1 of emergency governor lever passing by F1 and

connecting oil pipe to make the piston 12 move towards the right together

with the lever. At that time, 1 fly-ball shall move away the working

position and 2 fly-ball shall still be at the working position due to the

eccentricity of the lever. When the piston moves near the travel end, the

oil mouth E shall open and the pressure oil in chamber D1 shall enter into

the lower chamber under the oil ejecting valve through connecting pipe to

jack up the oil ejecting valve and small valve. Being shut off by the small

valve, the pressure oil can not enter into chamber K1. After the small

valve is pressed in manual, the pressure oil can enter into chamber K1

and eject towards the oil inlet of emergency governor through oil nozzle.


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Then 1 fly-ball shall be pushed out, the signal lamp on safety and

control box shall bebright. At that time the lever has moved away from

the upper of1 fly-ball, so main stop valve and regulating valve shall not

be shut off when1 fly-ball acting. After the button is released in manual,

the small valve shall reset and oil ejecting shall stop, the fly-ball shall

draw back into the shell. Then rotate the pilot valve to normal position, the

oil supplying for chamber F1 shall be shut off and the pressure oil in pipe

shall be discharged through 2 throttle hole. The oil ejecting valve and

small valve shall be at the lower limited position and the emergency

governor lever shall be back to the working position.

When test 2 fly-ball, the handle shall be clockwise rotated and the

pressure oil shall enter into another oil chamber D2 of emergency

governor lever, the action and reset process shall be the same with the

above.

When test one fly-ball, another fly-ball shall be in working state to ensure

safety of unit.

Safety system test shall be done according to the following principle:

Before or after overhaul, after accident shutdown or unit shutdown for a

long period, the test shall be done according to the complete criterion.

When operating normally, the test shall be done one time per 2000 hours

according to the standard criterion.

The complete criterion of safety system test:

Manually operate safety system for two times;

Do overspeed test of each fly-ball separately;

Raise speed and do combining test of two fly-balls;

Do oil ejecting test of each fly-ball;


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The standard criterion of safety system test:

Manually operate safet y system for two times;

Raise speed and do combining test of two fly-balls;

Do overspeed test of the fly-ball no acting in the above No.2 test

separately;

Do oil ejecting test of each fly-ball;

Annex safety overspeed test shall be done only in test station of factory

and power plant shall not do the test. Oil ejecting test shall be forbidden

when doing overspeed test of fly-ball for fear that the acting speed of

fly-ball shall be wrong.

4.4 Method of safety system test

Manually operate safety system

When steam turbine is idling, press the trip valve in manual. If main stop

valve and regulating valve can be shut off immediately, the system is

normal.

Do overspeed test of fly-ball separatelyWhen steam turbine is idling below speed of 3000r/min, do overspeed

test of1 fly-ball. Rotate pilot valve from normal position to2 position,

the unit speed shall be raised through DEH system till1 fly-ball acts at

specified speed and main stop valve and regulating valve are shut off.

After the test is over, rotate pilot valve from 2 position to normal

position, operate pilot valve and reset emergency governor sliding valve

to make main stop valve and regulating valve open again, regulate speed

to be 3000r/min.

To do overspeed test of2 fly-ball,rotate pilot valve from normal

position to 1 position, the rest steps shall be the same with the above


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mentioned. When acting speed of fly-balls is within 3330r/min3360r/min,

the fly-balls are considered being regulated properly.

Combing overspeed test of fly-balls

Make pilot valve at normal position, the rest steps shall be the same with

the above overspeed test of fly-balls separately.

The method of oil ejecting test of fly-balls refers to the above oil ejecting

test.

5. Brief introduction of governing units

5.1. High pressure oil-relay

High pressure oil-relay receives hydraulic pressure signals from DEH and

converts them into displacement of the piston, then controls regulating

valve through steam distribution lever and cam steam distribution device.

High pressure oil-relay consists of sliding valve and piston, etc. When

working normally, the oil sliding valve shall be at middle position and oilpiston shall be at balance position. When speed rises, the impulse oil

pressure shall drop and oil sliding valve shall move down. The chamber

upon oil piston shall open to pressure oil and the lower chamber shall

open to oil inlet of main oil pump, then the piston shall move down. When

speed drops, the process shall be opposite to the above.

The piston of high pressure oil-relay can balance at any position withintravel of 0250mm.The piston travel shall be indicated by indicator on

scale board. The travel of sliding valve can be measured by measuring

lever of sliding valve.

The LVDT displacement sensor shall be installed on piston bar of

oil- relay to feed back the displacement of piston to DEH control system.


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5.2. Automatic shutoff deviceAutomatic shutoff device is adopted to control open /shutoff of main stop

valve. The device is installed upon main stop valve directly and shall be

started up by startup valve so as to make main stop valve open. The lever

shall act and affect the spring seat to make the piston move up; the spring

force is increased till oil mouth C shuts off again. So each oil pressure

value shall be corresponding to a certain piston travel. When oil pressure

under sliding valve is 1.44MPa, main stop valve shall open fully, and then

rise oil pressure under sliding valve to be 1.96MPa, the sliding valve shall

move to the upper limited position due to the oil pressure. The oil mouth C

shall open fully. The oil pressure under automatic shutoff device is

1.96MPa and the open degree of main stop valve shall be kept to be the

maximum by the piston due to the oil pressure. Sliding valve 1 controls oil

mouth b1 and b2, its function is: (1) to open oil mouth b1 to move valve

bar of main stop valve; (2) to open oil mouth b1 and b2 fully so as to shut

off main stop vale fully. Loosen retention pin and rotate the handle

(anticlockwise rotating) to make the sliding valve move up, the pressure

oil under sliding valve 1(connecting to the chamber under sliding valve 2)

shall open to discharge oil through oil mouth b1, the oil pressure drops,

and piston 2 shall make main stop valve move down. When oil mouth b1

opens fully, the piston shall move down only about 15mm, which shall not

result load change of steam turbine. Then rotate the handle to make the

sliding valve move up, mouth b1 and b2 shall open fully; the oil pressure

under the sliding valve drops till it is not enough to overcome the spring

pre-loaded force, then the automatic shutoff device

shall shut off fully. There is signal device installed on automatic shutoff


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device. When main stop valve is nearly shut off fully, the inclined plate b

installed on bar shall press the end switch 7 to switch on the circuit, a light

signal shall be given to show complete shutoff of main stop valve.

5.3 Oil relief valve

The function of oil relief valve is to keep the oil pressure in lubricating

system (after oil cooler) to be a constant.

Structure of oil relief valve

The shell of oil relief valve shall be installed in pipeline directly. The valve

sleeve of the shell shall be located by shoulder K and a special clip 3;

sliding valve 4 shall be in balance under action of spring force and oil

pressure.

When oil pressure of lubricating system changes, the sliding valve shall

move up/down to change the open degree of the oil mouth on valve 2,

thus the discharge oil entering into oil tank shall change.

The oil pressure of lubricating system can be maintained by rotating bolt 8

and adjusting tightening fore of spring 6. The final tightening fore of spring

shall be adjusted at power station.

A buffer device shall be installed on oil relief valve to reduce fluctuation

and ensure stability when working. It consists of two throttle orifice plates.

The diameter of oil inlet hole of throttle orifice plate 5 is 1.8, the hole

diameter of oil outlet of throttle orifice plate 7 is3.2.

The pressure in buffer chamber shall change together with the change of

flow quantity passing the valve

Attention items when operating

The buffer oil pressure shall disappear when the hole of throttle orifice

plate 5 is blocked up, and then the oil pressure of lubricating system shall


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drop. When the hole of throttle orifice plate 7 is blocked up, the buffer oil

pressure and oil pressure of lubricating system shall rise. Under condition

of the above two, the valve shall be assembled again.

The nut locating throttle orifice plate shall be installed on sliding valve

reliably and caulked firmly.

Brief introduction of TSI instrument

The relevant monitoring and protecting system shall be set up to insure

safe, economical and reliable operation of steam turbine.

The monitoring and protecting system can continuously monitor many

important parameters involving safety of steam turbine, so it can help

operator determine faults during operating and shut off steam turbine

timely when unit works under abnormal condition and shall be damaged

seriously.

All relevant instruments adopted in the monitoring and protecting system

of the unit refer to Drawing of Electric Equipments.

Installation position of main instruments of TSI

The relevant manual shall be attached in the case packed with the

purchased instruments of the monitoring and protecting system. After

inspection and acceptance, the manual shall be submitted to relevant

functionary of power plant for preservation to avoid confusion in thefollowing installation.

The speed measuring instrument, protecting instrument for emergency

overspeed trip and monitoring instrument for axial displacement shall be

installed in front bearing seat of turbine. The speed measuring instrument

shall be installed on bracket of front end of main oil pump in front bearing


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seat. The protecting instrument for emergency overspeed trip and

monitoring instrument for axial displacement shall be installed on bracket

at emergency governor of turbine;

The instruments for measuring heat expansion shall be installed on both

outer sides of contacting position of front bearing seat and front base

frame which is near front bearing;

The vibration measuring instrument shall be installed on cover of each

bearing seat and the position is near vertical centerline of each bearing.

The installation screw shall be drilled at site according to the instrument

manual supplied by manufacturer;

The instrument for measuring relative expansion shall be installed on spilt

plane of rear bearing seat of steam turbine and the position is near the

coupling connecting steam turbine and generator.


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INSTALLATION SKETCH MAP OF PART TSI INSTRUMENTS


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INSTALLATION SKETCH OF BRACKET FOR MEASURING RELATIVE EXPANSION

Documents

Instruction Control System