Khai Niem Dk UBEX1 M1&2 I 51 0011e

General instructions

DOCUMENT STATUS: FOR APPROVAL

E15.08.04Revised after DRCR-M1&2-I-0037

D30.01.04Fourth issue

C09.10.03Third issue

B30.09.04Second issue

A14.09.03First issue

Rev.DateDescriptionDrwn.Chkd.Appd.

UONG BI 300 MW EXTENSION POWER PLANT

Owner:

EPC Contractor:

Subcontractor:

Document Title:

Power Island

Measuring, Control and Logic Function Concept

Project No.Format: A4Total Pages: 12

Designed by:

FunctionNameSignDate

Approved Seredenko 30.01.04

CheckedShvydchenko25.01.04

Draw Seredenko20.12.03

Document No.: UBEX1-M1&2-I-51-0011Date:

15.08.04Rev:

E

File:UBEX1-M1&2-I- 51-0011eFormat 4

1. ForewordThe operation and control concept provided in this document represents general description of the Unit control principles but does not detail the control logic.

More detailed information of the interactions between the different systems reference will be provided in the corresponding engineering documents:

P&I diagrams;

Technical Descriptions of the different systems;

Functional Control Diagrams;

Measuring Point Lists;

Alarm & Interlock Lists;

Command Signal Lists;

Information Transfer Lists;

etc.

Systems not determining the Unit operation and control concept are not considered in this document.

2. Requirements

The coal-fired Unit is designed for operation in the base mode of electric load control from the minimum load of 90 MW up to the rated load of 303 MW.

The Unit is able to be operated continuously in the range of 70-100% of the nominal output power at coal firing.

The Unit is also able to be operated continuously in the range of 30-70% of the nominal output power at coal firing using the reduced fuel oil.

The minimum load admissible for long-term period operation of the Unit is 30% of the rated.

The Unit operates in the constant pressure mode in the range of 90%-100% of the nominal rated load and the Unit is able to operate in the sliding pressure mode at normal operating conditions in the range of 30%-90% of the rated output load.The Unit is designed for base load operation.

The admissible level of the load changing rate in the adjusting range is 1 - 3% of the nominal power per minute.

These conditions are not applicable during the Unit start-up.

The Unit is capable to provide maximum load 318,15 MW at the turbine valves fully opened.

Power reserve above the nominal is provided to take part in frequency regulation in the grid of 220 KV.

This reserve is provided by the control valves of the steam turbine which should not be fully opened at the rated load 303 MW.

The Unit is be capable to withstand sudden loss of the load 318,15 MW without tripping. The Unit remains on plant auxiliaries load or on idle run using the turbine bypasses and is capable to resume maximum load within the shortest time.

After total unloading the Unit operation at the idle run or at the plant auxiliary load is limited to 120 minutes.

The Unit control system will provide the automatic mode of the Unit operation by the operators command from the moment of the boiler is available for ignition.

During the start-up the boiler ignition, pressure raising and the turbine run up, loading up to the set power are effected automatically.

The operator at the Plant Control Room (PCR) takes part in the Unit control only with the following purpose:

selection of the working and stand by equipment;

setting of the required load;

separate command for start-up or switching off the selected group of the Unit equipment;

separate command for the generator synchronization after receiving the permission from the power grid dispatcher.

Automatic start-up is also effected for the Unit auxiliary equipment.

The Unit automatic control is provided for normal operational modes complying with the project in all respects. If the Unit is not used in accordance with the project i.e. if part of the equipment is put shutdown (i.e. some stand by mechanisms or auxiliary equipment, without which it is permissible to operate the Unit, e.g. part of the regenerative heaters of the turbine) then this equipment is controlled manually.

Automatic protections, closed and opened control loops provide the safe operation of the Unit within the manual control mode.

The Unit is also started up in the manual control mode after considerable overhauls or because of necessity to perform tests during the start-up.

The task of the automatic control system is to keep operating parameters and in general the operation of the equipment in certain limits at changing the operation modes. If due to failure of the equipment or faults with automatic devices the process exceeds the above mentioned the limits but there is no necessity to trip the Unit the actuation of non urgent alarm is provided.

At the same time such automatic operations as:

- load limitation;

- load decreasing;

- automatic start-up of the auxiliary equipment;

- switching off, if possible, faulty equipment, etc.

will be effected to transfer the Unit into the mode providing its long-term operation.

In case of a trip of the 220 KV circuit breaker in the switchyard of the Unit due to external fault the Unit remains in operation providing house load.

The subsequently synchronization of the turbine-generator unit is effected automatically by the operators command and the Unit coordinator effects necessary control functions for preparation of automatic load restoration.

The Unit cannot be start-up at the inhibiting action of the protections.

In case of two or more excess plants or mechanisms (drives) the automatic switching functions are provided.

All valves, gate valves, etc. which should change their position in the process of the operation or under the safety requirements during start-up, trip and normal operation are equipped with motors and are controlled automatically and remotely. If during start-up some actions (air displacement, draining, etc.) are not to be done at the strictly fixed moments and could be performed some time later (eg. within 12 hours), then such actions are performed by a plant attendant by means of manual valve.

Manual valves, gate valves, etc. are used for maintenance, first filling up, air displacement and draining.

3. The Unit Main Features

3.1 Power Generation:

The electric power generation supplied to the grid is three phases of 50 Hertz AC, at a nominal voltage of 220 kV after the Main Step-Up Transformer.

The total power output of the Unit is 303 MW at the design conditions and the main fuel as specified in the Contract (i.e. ambient temperature = 32.2C, cooling water temperature = 26C).

3.2 Standard Voltages:

The following voltages rated values are applied:

Transmission voltage220 kV

The generator voltage19 kV

The intermediate voltage 11 kV

The medium voltage bus

(3-phase, 3 wire system)6.6 KV

The low voltage bus

(3-phase, 4 wire system)400 V

The low voltage bus

(2 wire system)230 V

Uninterrupted Power Supply (UPS)400/ 230 V

Main DC voltage220 V DC

DC voltage for electronic equipment48 V DC

Regulating valves with thyristor amplifiers24 V DC

The rated frequency of the AC voltages is 50 Hz.The frequency variation range is +/- 5%.

3.3 Fuel Supply:

3.3.1 Coal supply and firing system

Coal is the main fuel.

Coal is delivered from fuel supply to the pulverized coal system.

Four pulverized coal systems are provided:

Each system has the following equipment:

raw coal bunker;

bayonet gate;

raw coal feeder;

ball-tube mill;

separator;

pulverised coal cyclone collector;

mill fan.

Each two pulverized coal systems operate for its pulverised coal bunker. There are two pulverised coal bunkers are provided.

Pulverized coal is supplied to the boiler burners through the pulverized coal feeders, located at the outlet from the pulverized coal bunkers, by means of high concentration pulverized coal system. Pulverized coal delivery is effected by air from 2x100% air blower.

The secondary air supply to the burners is effected by two FD fans. Primary air supply is effected by four primary-air fans.

Mill exhausters provide discharge of dusty air from cyclone collectors to the discharge nozzles of the boiler furnace.

Coal design parameters for the mills are as follows:

- ash 31.0 wt%

-total moisture 12.00%

- surface moisture 10%

- self- moisture 2.0%

- Hargrove milling index (HGI) 40

- raw coal average size maximum 20 mm

The mills provide the following degree of fineness min. 90% through the sieve with the mesh 200.Total capacity of raw coal bunkers and pulverised coal bunkers provides 14 hours of the boiler operation at the maximum steam output.At that:

raw coal bunker capacity provides 10 hours of the boiler operation at the maximum load (BMCR);

pulverised coal bunker capacity provides 4 hours of the boiler operation at the maximum load (BMCR).

3.3.2 Fuel oil supply and firing system

Fuel oil is the back-up fuel.Fuel oil is used for the Boiler ignition and lighting at firing solid fuel in the range 30%-70% of the nominal output.Fuel oil firing system provides 40% thermal load of the (BMCR) duration steam output.Fuel oil firing system is designed for continuous operation.Fuel oil firing system includes:

fuel oil intake and storage system;

2x100% fuel oil pumps of the 1st stage;

2x100% fuel oil pumps of the 2nd stage;

fuel oil cleaning filters;

fuel oil heaters;

fuel oil nozzles and auxiliary equipment.

Fuel oil is heated by steam heaters in the fuel oil storage tanks and fuel oil supply system. Minimum fuel oil heating temperature is 22C.

The boiler fuel oil pumps are able to start at fuel oil temperature 22C.For fuel oil firing the atomising steam fuel oil nozzles are used.The fuel oil nozzles are of withdrawable construction but on the lower elevation where they are permanently in the burners are cooled by steam.

The fuel oil nozzles are equipped with electric devices of fuel oil ignition and flame monitoring.The flame monitoring for each kind of fuel is provided by separate flame scanners. Besides, the general flame monitoring in the boiler furnace and monitoring cameras system are provided.

The characteristic of the main and back-up fuel is mentioned in ITB (Book 4.V1 Part A1 General Technical Requirements, paragraph 2.1.3.2).3.3.3 Cooling water supply

Cooling water supply is effected from the circulation water pump station which has 2x50% circulating water pumps for the Unit auxiliaries.The designed value of the cooling water temperature is 26C.Long-term operation of the turbine at the cooling water temperature 30,5C is possible.In order to limit the growth of water organisms the chlorination system in the circulating water pump plant area should be provided for water chlorination in the top flanges area.Each input pipeline of the circulating water should have debris filter with the mesh size approx. 10 mm.The ball cleaning system is used for cleaning of the condenser tubes from mineral and sludgy sediments by means of elastic balls made of porous rubber.When the ball cleaning system is in operation the load does not decrease.3.3.4 Water treatment systemThe influent water for the water treatment plant is the water from the Uong Bi river, the chemical composition of which is indicated in p. 2.1.3.1 ITB Book 4. VI. Part 2.1.Distilled water quality for boiler make-up after water treatment plant must satisfy the following rate, not more:General hardness, g/dm3 ................................. ... 0,2

Silicon acid content in translation to SiO2, g/dm3 ........................15

Sodium compound content, g/dm3 ......... 5

Specific electric conductivity, S/m...................... ..... 0,15

Chloride content, g/dm3 .. 3

Sulphate content, g/dm3 .... .. 3

General organic carbon, g/dm3 ... .. 300

4. Major Components of the Unit4.1 The Steam Generator

The steam generator -920-17, 6-543 (Model 318.) is the drum, gas-tight steam generator with natural circulation, with balanced draft.The boiler is designed for operation with the condensing turbine K-300-170-1P and the generator TBB-320-2T3.The main fuel is pulverised anthracite coal, the back-up fuel is fuel oil.The boiler is equipped with sixteen swirl burners mounted on the front and rear walls of the furnace in the opposite order on two decks by eight burners per each deck.Each burner is equipped with the atomising steam fuel oil nozzle.

Eight nozzles of the drying agent discharge are located over the burners in the opposite order on the front and rear walls of the furnace.

Brief characteristic of the boiler ander nominal load (303 MW):

rated steam output is 861,32 t/h;

drum pressure is 195 kgf/cm2;

main steam temperature is 543C;

reheat steam temperature is 543C;

main steam pressure is 179 kgf/cm2;

reheat steam pressure is 38.9 kgf/cm2.

4.2 The Steam TurbineThe steam turbine K-300-170-1P is a tandem three-cylinders unit consisting of single-flow HP cylinder with the flow turn, single-flow IP cylinder and double-flow LP cylinder.HP cylinder has nozzle steam distribution which is performed in the form of two HP valves sets consisting of one stop and two control valves.HP cylinder blading is of the reactive type. HP cylinder has eighteen stages, the first one of them is the control stage.After HP cylinder the steam is supplied to the reheat.IP cylinder has throttle steam distribution which is performed in the form of two valves sets consisting of one stop and one control valves.IP cylinder blading is of the active type. IP cylinder has fifteen stages.

All stop and control valves are of the balanced type.After IP cylinder the steam is supplied by two receiver pipes to LP cylinder.

LP cylinder has four stages in each flow. The length of the last stage turbine rotor blade is 1000 mm.LP cylinder steam inlet is effected by two pipelines located in the upper part of the cylinder.HP, IP and LP rotors are solid-forged.

The turbine rotors and the generator rotor are connected by rigid couplings.

The rotor rotation direction is clockwise looking from the HP cylinder towards the generator.The rotor rated rotation speed is 50 sec.-1 (3000 r/min.).The turbine is designed for operation at the following rated parameters:

main steam absolute pressure ahead of stop valves of HP

cylinder. 171 kgf/cm2;

main steam temperature ahead of stop valves of HP

cylinder...... 538C;

main steam absolute pressure ahead of stop (shut off) valves of IP cylinder.. 37,57 kgf/cm2;

steam temperature after the reheat ahead of stop (shut off)

valves of IP cylinder...... 538C;

design absolute pressure in the condenser at the cooling water

temperature of 26C 0,065 kgf/cm2.

The design cooling water temperature 26,02C.

The mass flow of main steam at the rated parameters. 861,32 t/h.

The maximum mass flow of main steam at the rated

parameters 920,0 t/h.4.3 The Main CondenserThe turbine condenser is of two-flow, single-pass on the cooling water side design. The condenser is designed to operate with brackish water. The cooling surface area is 17900 m2.The rated volume flow of the cooling water is.. 38580 m3/h.The hydraulic resistance of the condenser at the rated flow of the cooling water is max. .. 0,50 kgf/cm2.The maximum admissible overpressure of the cooling water in the condenser water boxes is . 2,5 kgf/cm2.The turbine is able to operate with one half of the condenser that allows cleaning other half of condenser during of the turbine activity.The supply and discharge of the cooling water from each half of the condenser is separate which enables to clean the half of the condenser when the turbine is in operation.The condenser is mounted on spring supports for compensation of thermal expansions.

The condenser shell is welded of sheet carbon steel. The tubes of condensing surface are made of titanium, the tube sheets are made of carbon steel coated with titanium.The air-steam mixture evacuation from the condenser is effected by steam-jet ejectors.The working steam of the ejectors is the steam from the auxiliary header with the pressure 14 kgf/cm2 and from the deaerator vented steam line.4.4 The GeneratorThe steam turbine is connected to the synchronous three-phase AC generator of TBB-320-2T3 type which has combined cooling (water and hydrogen) and static excitation system.The generator has the following technical specification:

total power 356.5 MVA;

active power 303 MW;

generator output voltage 19 KV;

stator current 10830 A;

coefficient of efficiency 98,7%;

frequency 50 Hz;

rated hydrogen pressure 4.0 kgf/cm2;

maximum hydrogen pressure 5.0 kgf/cm2;

cooling hydrogen temperature 42C;

distilled water temperature in the stator winding 40C.4.5 The Turbine Bypass SystemThe turbine bypass system provides:

- keeping of main steam and reheat steam pressure required for the Turbine start-up;

- uninterrupted operation of the Unit (operation with auxiliaries load) in case of disconnection from the grid and total load runback.4.5.1 HP BYPASS

1 x 60 % HP steam bypass plant connects the main steam lines with the cold reheat lines. Main steam pressure is reduced by throttling in the steam valve.Steam cooling is provided by water injection from the feed water pumps pressure header. The bypass valve has a hydraulic drive with the closed fault-tolerant position.4.5.2 LP BYPASS2 x 50% LP steam bypass valves are located near the turbine and connect the hot reheat steam system with the turbine condenser. Hot reheat steam pressure is reduced by throttling in the steam valve, hot reheat steam temperature is decreased by water injection from the condensate pumps pressure header. The valves have hydraulic drives with the closed fault-tolerant position.4.6 The Air-Flue Gas Plant4.6.1 Forced Draft Fans2x70% forced draft fans are provided for supplying secondry air to the burners.The forced draft fans are of centrifugal type with aerodynamic blade and hydraulic coupling for rotation speed control.The guide vanes are not provided.4.6.2 Induced Draft Fans2x70% induced draft fans are provided for evacuation of flue gases from the boiler and atmospheric emission through the Flue Gas Desulphurization system and the chimney.The induced draft fans are of centrifugal type with aerodynamic blade and hydraulic coupling for rotation speed control.The guide vanes are not provided.4.6.3 Primary Air Fans4x25% primary air fans with the constant rotation speed are provided for supplying primary air to the boiler burners.4.7 DeaeratorThe Deaerator provides water deaeration at the pressure corresponding to the current load of the Turbine and also at the operation with low pressure heaters partially off (LPH-3).Increasing pressure thermal deaerator with horizontal column has the following characteristics:

- rated output 1000 t/h;

- absolute rated working pressure.. 11,0 kgf/cm2;

- design pressure, gauge pressure. 10,35 kgf/cm2;

- design temperature. 200C;

- water temperature rise at the rated output.. ~33C;

- dissolved oxygen content in the deaerated water

at the Deaerator outlet, maximum.. 7 g/kg;

- dissolved oxygen content in the main condensate

at the Deaerator inlet, maximum 20 g/kg.At changing the rated load of the Unit from 30% to 105% of the nominal the Deaerator should operate in sliding pressure mode at changing the working pressure in the Deaerator shell from 2,85 to 10,38 kgf/cm2 in accordance with the pressure in the Turbine extraction.In the load range from 30% to 15% of the nominal the Deaerator operates at the constant working pressure in the Deaerator shell in the possible range from 1,2 to 2,85 kgf/cm2 (set by operator) and water heating in the Deaerator from 40 to 70.The Deaerator provides stable operation during Turbine load runback from nominal to bypass operation at the output not more than 30% of the nominal, pressure 2,85 kgf/cm2 and water heating in the Deaerator from min. 40 to saturation temperature.5. Steam-Water CycleThe steam-water cycle is described in brief as follows:Condensate collected in the condenser is supplied to the feed water deaerator by means of 2 x 100% condensate pumps. The pumps operate at fixed speed. The condensate flow to the Deaerator and feed water storage tank is controlled by two control valves downstream the pumps. The pumps are protected by minimum flow valves.The condensate is heated in the condenser of gland steam supplied from glands labyrinths of the turbine (gland heater) and in three LP heaters.From the feed water tank the feed water is transferred to the boiler by means of 3 x 50% feed water pumps, equipped with variable speed couplings.Between the boiler feed pumps and the boiler economizer the feed water is heated in two HP heaters and steam cooler of HPH 5.The flow control of the boiler is established before HP heaters.The feed-water on injections to superheater goes from a pressure piping of the boiler feed pumps before flow control valves. The feed-water on injections to reheater goes from a pressure piping of feed pumps before flow control and from intermediate stage of the boiler feed pumps.Feed water is also utilized as spray water to the HP bypass plant and sprays to the Boiler.Superheated steam generated in the boiler is supplied to the turbine connected to the generator.The steam extractions from the turbine and cold reheat line provide the heating of feed water and condensate in HP and LP heaters, deaerator.The data of the steam extractions for regeneration at the rated power mode at the rated parameters according to the p.4.2, regeneration system being totally switch on and absence of additional steam extractions are listed in the table 1.

Table 1

Steam consumerSteam parameters in the extraction chamberMass flow of the turbine extracted steam, t/h

Absolute pressure, kgf/cm2Temperature, C (relative humidity, %)

HPH No.640,9932789,8

HPH No.517,2342233,8

Deaerator9,6834126,6 to 12,8

LHP No.34,2123851,0

LHP No.21,2111637,8 to 1,9

LHP No.10,26365,7 (5,4)22,7

Exhaust steam of the LP cylinder is led to the main condenser where steam is condensed and deaerated.Air extraction from the condenser during start up as well as during normal operation is provided by means of a steam ejector system.Steam turbine gland sealing during start-up is provided from the auxiliary steam system (auxiliary header). During normal operation it is taken from the turbine (self-gland).6. The Unit Control System6.1 Degree of AutomationThe Unit control system utilizes advanced microprocessor technology, which provides the high degree of automation.The control of a technological process of the unit is executed as follows:

main process control is performed from the Plant Control Room (PCR);

water treatment system control, etc. is performed from the corresponding Local Control Rooms (LCR).All signals required for control and monitoring of the equipment are supplied to the corresponding control room. The information exchange between PCR and Local Control Rooms is provided.Various other station equipment systems are provided with local control units (PLC). The equipment operates fully automatically. All necessary control and monitoring functions are carried out by the local control units. Remote operation and control (on/off commands and respective feedback signals) for the local control units are executed only via PCR or corresponding LCR. Remote individual operation and control are not executed via the PCR or corresponding LCR.Start-up, trip and other operation modes set beforehand are performed by the piggy-back control function of the distributed control system from the PCR.Cold, warm and hot start-ups of the Unit are absolutely automated starting from the boiler ignition but for the Generator synchronization the operator confirmation is required.At the very hot start-up with the operation of the turbine bypasses and auxiliary equipment being in the hot stand-by the total automation up to the start-up level by one pushbutton is provided with an operator confirmation for the Generator synchronization.Normal operation, load variations and run backs are performed automatically.All processes control is effected from PCR or corresponding LCR through PWS (Operator Workstation) as man-machine interface.6.2 Control System StructureThe control system structure has vertical hierarchy and is independent of the Unit protections system.6.2.1 Control of Main Plant.

The control system has the following structure and control levels:6.2.1.1 The structure of the open loop controls:

Level 1: Unit Level Control:

- Boiler Control;

- Turbogenerator Control;

- the common Unit equipment control.Level 2: Group Control level (FG)Individual control for each function group (FG) within the Unit level control.Level 3: Sub Group Control Level (FG-S).Individual Control for each Sub-Group within the group level control.Level 4: Drive Level ControlIndividual drive control within the subgroup level control, or individual control beyond the subgroup level control (as the trip of separate mechanisms).The drive control level is the lowest automation level, control and monitoring for each drive is effected individually, including the processing of protection and interlocking signals which cannot be avoided in the remote control mode.The group and subgroup control level perform all tasks for automatic start and stop of the respective mechanisms groups. The Function Groups control clearly defined particular process depending on the technological structure.The following functions are provided at the function groups (subgroups) control level:- information exchange between the groups including the Unit Coordinator;

- formation of the control commands sequence in accordance with the technological algorithm;

- forming of the information about sequence program carry-out and completion;

- checking of the specified process conditions taking into account the time factors (checking of the execution terms of the functional group step actions within the defined time).The Unit control level coordinates the operation of the function groups of major parts of the Unit, such as the Boiler, the Turbine, the Generator and also evaluates state of the Unit equipment and takes a decision with regard to start-up modes (cold, warm hot start-up, etc.), shutdown modes (scheduled, emergency, etc.) and also the other operation modes (load runback up to the safe load or auxiliary load, etc.)6.2.1.2 The structure of the closed loop controls:Level 1: The Unit Level ControlThe Unit Coordinator.Level 2: The Group Control levelMaster controllers of the functional group parameters control.Level 3: Sub Group Control LevelIndividual and submaster controllers.Level 4: Drives Level ControlThe regulators operate under the standard control rules on the actuating devices with constant rotation speed. Commands to control actuating devices are pulse-modulating.On moving the regulators into automatic mode the following types bumpless switching are provided:

- for the set value of the controlled parameter (dynamic balancing with the rate of changing the current value of the controlled parameter set beforehand);

- for the current value of the controlled parameter (static balancing).Bumpless switching on is provided as at automatic step sequenser step logic as at remote (operator) switching of the regulator.Automatic switching off the regulator with change-over to remote control of the regulating device and corresponding alarming is performed in the following cases:

- at failure of the sensor measuring the controlled parameter;

- at failure or lack of power supply to the scheme of the regulating device control.6.2.2 Control of Auxiliary Equipment

One of such systems for example is the water treatment plant.These control systems have the following structure and control levels:Level1: The Group Control level (FG).This level starts and controls the slave subgroups (FG-S) of open and closed control loops automatically and in the required sequence.Level 2: Sub Group Control Level (FG-S).Individual control for each subgroup within the limits of the Group Control Level.Level 3: Drives Level Control.These systems will be operated and controlled separately from the corresponding LCR.All the control levels are accessible from LCR and only Group Control Level is accessible from PCR.6.3 Main Open Loop Controls (Discrete Control)The single function groups are combined at the Unit level within the main function groups of the boiler, turbogenerator and common unit equipment in order to obtain the overall automatic function of the process.6.3.1 The Unit Coordinator

The Unit Coordinator automatically and in the required sequence starts the boiler coordinator, the turbogenerator coordinator, functional groups of the common station equipment.6.3.2 The Boiler Coordinator

The Boiler Coordinator controls the boiler function groups (FG) of the upper control level within the Unit level limits.These function groups, operated in the required sequence, start the automatic ignition and loading of the boiler and will keep the boiler metal conditions within the control system limits.6.3.3 The Turbogenerator Coordinator

The turbogenerator coordinator controls the function groups (FG) of the turbine upper control level operating within the Unit level limits.These function groups in the required sequence, start the groups, the automatic start and loading of the turbine up to the set power , with all that the control system limits of the turbine Stress Monitor will be kept.6.3.4 The Common Station Equipment Function Group

This function group in the required sequence effects the start of the Unit auxiliary equipment.Appendix 1 contains the structural scheme of the Unit Discrete Control.

If necessary the List of functional groups could be changed.6.4 The Main Closed Control Loops of the Unit (Analogue Control)The single controllers are combined at unit level within the Unit Coordinator limits in order to obtain the overall process automatic control.The structural scheme of the Unit automatic control is indicated in the Appendix No.2.6.4.1 The Unit Coordinator (Unit Master)

The Unit coordinator operates interacting with the Boiler Master, forming the set value on fuel flow for the fuel controller and the Turbine Controller governing the control valves of the Turbine.Together with the above regulators the Unit Master provides the following modes of the Unit control:

- Manual mode (Mode a);

- Boiler follows mode (Mode b);

- Turbine follows mode (Mode c);

- Local Coordinated mode (Mode d);

- Remote Coordinated mode (Mode e).6.4.1.1 Manual mode of the Unit controlThere are three possible modes of the manual control:Manual mode 1. In this mode all regulators are switched off. Control of the Turbine, fuel and air supply to the Boiler is effected by operator remotely from PCR.Manual mode 2. In this control mode of the Turbine and fuel supply to the Boiler is effected by operator remotely from the PCR.Air flow to the Boiler is controlled by the common air (FD fans) regulator according to the ratio fuel-air without correction on oxygen.Manual mode 3. In this mode the Turbine control is effected by operator remotely from PCR. The fuel regulator is in automatic mode and controls fuel supply to the Boiler according to the command from the Unit coordinator. Regulator of the steam pressure ahead of the Turbine is disconnected from the fuel regulator. Common air regulator is in operation according to the ratio fuel-air.6.4.1.2 Boiler follows ModeIn this mode the Turbine control is effected by operator remotely from PCR. The common air regulator is in operation. The fuel regulator is in the automatic mode and keeps the steam pressure ahead of the Turbine (the regulator of the steam pressure ahead of the Turbine is connected to the fuel regulator). The regulator of the steam pressure ahead of the Turbine can operate in the mode of keeping the constant pressure (170 kgf/cm2) or in the mode of sliding pressure. At operation in the sliding pressure mode the task to the regulator is formed depending on the Unit load. In the Boiler follows mode the regulator of valves position and frequency-response equalizer are off.6.4.1.3 Turbine follows ModeIn this mode the keeping of the steam pressure ahead of the Turbine is effected by the regulators of the Turbine Controller. The modes of keeping the steam constant pressure and steam sliding pressure are possible.Fuel and air regulators are in operation. The fuel regulator operates under the task coming from the Unit coordinator. The regulator of steam pressure in the Boiler Master is off. The frequency-response equalizer is also off in this mode.6.4.1.4 Local Coordinated ModeIn this mode task and speed of changing under the load is controlled by operator from the PCR.The fuel regulator is put into operation according to the scheme described in the part Boiler follows mode.Valves position regulator is connected in addition to the Boilers Master steam pressure regulator. This valves position regulator provides open position of three control valves of the Turbine at the load lower than 90% in the sliding pressure mode.The Turbine regulator keeps the Unit power in accordance with the setting coming from the Unit coordinator.When the Power Unit takes part in grid frequency control the frequency-response equalizer is connected to the power regulator. In case of the frequency deviation from the dead band limits the frequency-response equalizer changes the task on the static characteristic frequency-power.The regulator of steam minimum pressure ahead of the Turbine is also in operation. This regulator does not permit to decrease the pressure ahead of the Turbine in the process of load changing lower than the set point of the set minimum pressure (SPmin LS Pressure). The set point is sliding and it is determined by the following ratio:SPmin LS Pressure = SP Load Turb Act P, whereSP Load Turb Act the set point on the steam pressure ahead of the Turbine;P admissible deviation from the set value.Limitation on high limit pressure ahead of the Turbine is effected by the HP Bypass, which starts to operate when the set point is exceeded.The set point is determined by the ratio:SPmax LS Pressure = SP Load Turb Act + PWhen forming the set value of the power (SP Load Unit Act) the limitations on minimum and maximum power are taken into consideration which are determined by the quantity of operating mechanisms, pulverized-coal feeders, nozzles; load of fans groups.Set point of power what coming to the Turbine Controller is formed by means of the Boiler model SP Load Turb Act = f(SP Load Unit Act) which takes into account the Boiler persistence. In a similar manner the task on pressure ahead of the Turbine is formed by means of the Boiler model SP Load Turb Act = f(SP Load Unit Act).In order to provide acceleration of the Boiler the speed up signals on SP load Turb Act and the frequency-response equalizer are introduced in the scheme of setting formation for the fuel regulator.6.4.1.5 Remote Coordinated ModeIn this mode the load setting is specified by operator from the dispatch center, speed of load variation is specified by operator from the PCR.In all other respects the operation of the regulators is the same as in the Local Coordinated Mode.6.4.2 Boiler Master

The Boiler Master is the part of the Unit Coordinator.See the structural scheme of the Unit automatic control provided in the Appendix No.2.In the modes Boiler follows, Local Coordinated Mode and Remote Coordinated Mode the Boiler Master keeps the constant steam pressure at the Boiler outlet.The Boiler Master forms the setting for all modes regulator of fuel supply and current load setting for the Turbine Controller.6.4.3 Turbine Controller

The structural scheme of the Turbine Controller is provided in the Appendix No.3.The Controller performs the following functions:

- speed control;

- load control;

- frequency correction;

- inlet steam pressure control;

- valves control;

- minimum pressure control;- maximum pressure control in the control stage;

- control valves position control;

- thermal stress evaluation;

- control system tests;

- UCTE test;

- improvement of the Turbine overspeed protection in case of failure in

hydraulic control system.More detailed information about the Turbine Controller functions is given in UBEX1-M1&2-I-52-0001 Control System Concept and Configuration Diagrams, incl. Fail Safe Protection.6.4.4 HP Bypass Control

HP-Bypass provides main steam pressure control and temperature of the steam discharged to the steam lines of the cold reheat at the Unit start-up and the Turbine trip and also as a safety valve for main steam maximum pressure exceeding ahead of the Turbine.The structural scheme of the Turbine bypasses control is given in the Appendix No.4Main steam pressure control by HP-BypassDuring start-up the set point for HP-bypass is developed by the scheme of the required value (RV) formation which forms the current set point of live steam pressure according to the requirements of the Boiler. When the current set point reaches the value set for the turbine start, which depends on start-up conditions (cold, warm or hot) the current set point remains unchanged and is controlled by HP-bypass pressure regulator.In the process of start-up proceeding as the control valves of the turbine HP cylinder are opened, HP-bypass will be closed.The Unit coordinator takes upon itself the setting function for HP-bypass by the signal the turbine HP cylinder switching on.When this mode of operation begins the set point of main steam pressure for HP-bypass plant is increased immediately by 10 kgf/cm2 of the working pressure that is specified by the Unit coordinator and depends upon the Unit load.If failures take place which result in pressure increase the HP-bypass valve is opened while the main steam pressure exceeds the set point of main steam pressure for HP-bypass plant consequently limiting the maximum pressure of main steam.When the turbine turbine is not to take up the complete main steam flow (the Unit runback load) the set point of main steam pressure for HP-bypass is decreased immediately up to the working pressure set point depending on the load specified in the Unit coordinator.HP-bypass is opened and controls the main steam pressure under this working pressure set point. It continues until either the turbine starts to accept steam in full or the boiler shut down takes place.HP-bypass has an attemperation system which is effected by the injection to the HP-bypass steam attemperator and maintains the set steam temperature at the HP-bypass outlet.Depending on water pressure to the spray and steam pressure in the reheat line the gain factor of the temperature regulator is changed.Injection valve is closed automatically if the steam pressure control valve is opened less than 3%.Manual operationsThe main steam pressure set point for HP-bypass could be switched over to the manual mode and adjusted by operator. It enables to set manually the required main steam pressure for the turbine during the boiler start-up and the pressure set point for HP-bypass during the Unit operation.6.4.5 LP Bypass Control

LP-Bypass serves as a control valve of reheat steam pressure and temperature of the steam discharged to the condenser during the Unit start-up and in the Unit emergency modes. If steam discharge to the condenser is impossible due to vacuum decay, temperature increase in the condenser, injection water pressure decrease, the steam discharge from the reheat header is provided by means of the safety valves opening and LP-bypass is used as a safety shutoff valve.Reheat steam pressure control by LP-BypassThe automatic regulator LP-bypass keeps the constant reheat steam pressure set at the level 12-15 kgf/cm2 within the 0-30% range of the turbine load. At increasing the turbine load above 30% (HP cylinder is on) the set point for LP-bypass pressure regulator is set as variable depending upon the pressure in the control stage and it will be 10% more than the current pressure in the reheat line corresponding to the given load (it is determined by functional dependence f(x)).At the turbine load being more than 30% the LP-bypass is closed in the normal mode.LP-bypass has an attemperation system which is effected by the injection to the LP-bypass steam attemperator and provides keeping of the set steam temperature at the LP-bypass outlet.Depending on steam temperature and pressure in the reheat line the gain factor of the temperature regulator is changed.Injection valve is closed automatically if the steam pressure control valve is opened less than 3%.Manual operationsThe set point for LP-bypass pressure regulator could be switched over to the manual mode and adjusted by operator. It enables to set manually the required pressure in the reheat line during the boiler start-up and the pressure set point for LP-bypass during the Unit operation.6.4.6 Fuel Control

The Boiler fuel feeding automatic control system provides fuel for the required steam rate of the Boiler.The structural scheme of the regulator is given in the Appendix No.5.Fuel control is performed by the following means:

- fuel oil pressure regulator;

- fuel oil flow regulator;

- fully-variable mode fuel regulator.Fuel oil pressure regulator maintains the starting fuel pressure during ignition of oil nozzles at the Boiler start-up.After turning the oil nozzles off the regulator remains in operation keeping the pressure in fuel oil line (ahead of the nozzles) corresponding to the flow 10,5% of the rated thermal load for eight burners of the lower deck to be re-ignited in time at the decreased loads.The regulator is performed under single-loop scheme and receives the signals of the set and actual pressure of fuel oil.Automatic task setting to the regulator is provided depending upon the Boiler operation mode.Fuel oil flow regulator stabilizes fuel oil flow at combined combustion pulverized coal and fuel oil.In a load range from 30 up to 50% regulator provides the fixed flow of fuel oil corresponding to making of a thermal output equal 15 % from BMCR.In a load range from 50 up to 70% regulator provides the fixed flow of fuel oil corresponding to making of a thermal output equal 10.5% from BMCR.Fully-variadle mode fuel regulator keeps the total fuel flow (fuel oil + pulverized coal) in all operation modes of the Boiler in accordance with the setpoint.The following signals are supplied to the regulator input: actual fuel flow coming to the Boiler and setpoint.Setpoint is formed either by the Boiler Master in normal operation modes in the control range or by the fuel programmer in the modes of ignition and Boiler loading during start-up.When the protections switching the Boiler to the decreased load operate setpoint equal 30%, 50% or 70% of the nominal fuel flow are switched automatically to the regulator.The signal characterizing the total thermal load of the Boiler is formed as total signals of fuel oil flow and quantity of the pulverized-coal as supplied by the pulverized coal feeders as fed to the Boiler furnace from the pulverized coal systems.The signal of the pulverized coal quantity fed from the pulverized-coal system through the feeding nozzles is formed by the summation unit by switching on the pulverized-coal systems.The signal of fuel oil flow is formed as the measured difference between fuel oil flow to the Boiler and to the recirculation flow.The signal of the pulverized coal quantity supplied by the pulverized coal feeders is an indirect signal calculated from the sum of the control valve position signals of each pulverized coal feeder. This signal is entered in the regulator with the Boiler actual heat generation correction. The correction signal characterizes specific heat productivity of the Boiler by the coal constituent.The product Rp*Fc1 formed by the multiplier unit reflects the total Boiler output with reference to pulverized coal.The regulator effects either on the master integrator forming the task to the regulators of the pulverized coal feeders capacity or on the fuel oil control valve.The regulator switches to the fuel oil control valve after ignition of all fuel oil burners at the Boiler start-up and loading up to 30% and also at the Boiler 30% load operation and its change-over to fuel oil firing.The regulator is connected to the pulverized coal feeders after switching on all the pulverized coal feeders at the minimum load during the Boiler start-up and keeps the set load in the working range 100-30% as at the Boiler pulverized coal operation as at combined firing of pulverized coal and fuel oil.Connection of the regulators to the actuating devices is effected automatically by the logic signals.In the silent state the dynamic balancing of the regulators is provided for their subsequent bumpless switching on.6.4.7 Common (Primary & Secondary) Air Pressure Regulator

The regulator is designed for keeping the set excess air during fuel firing. The regulator is performed according to the fuel-air ratio with the correction on the average content of O2 in flue gases or q3 (chemical underburning).The structural scheme of the regulator is given in the Appendix No.6.The regulator includes the ratio regulator and the adjustor.The following signals are supplied to the ratio regulator: the signals of total air flow to the burners and discharge nozzles, setting signal of total fuel flow with O2 or q3 correction and derivative signal of fuel oil flow.The ratio regulator effects on air supply to the Boiler through the system of synchronization of actuating devices movement of both FD fans.The maximum of two correction signals is supplied to the adjustor inlet (O2 or q3) what enables to perform the setting correction to the ratio regulator at different furnace modes.The correction signal is input by means of the multiplier unit; it enables to improve the accuracy of keeping the ratio fuel-air in all Boiler modes. The dynamic correction and required static dependence of the average set correction signal on the total fuel flow are provided. The adjustor scheme contains the prohibition to change the output signal for increase at the FD fan hydraulic coupling being opened in full. The regulator scheme also provides different operation modes of the ratio regulator and the adjustor (operation with one FD fan, switching off the adjustor), automatic balancing of the regulators at their switching off.6.4.8 Primary Air Flow Regulators

Four air flow regulators are provided in accordance with the quantity of pulverized coal systems.Each regulator keeps primary air flow to the pulverized coal feeders of four burners.The structural scheme of the regulator is given in the Appendix No.7.The regulator effects on corresponding guide vanes of the primary air fan.The signal of the primary air flow setting depending on the Boiler steam load and the controlled parameter primary air flow, determined by the differential on measuring device with temperature correction and calculated for one primary air fan, are supplied to each regulator input.The regulator scheme provides the limitation on minimum admissible value of the primary air flow.At switching off the regulator its dynamic balancing is put in.6.4.9 Furnace Pressure Regulator

It is designed to keep the depression in the furnace during the Boiler operation at the balanced draught.The structural scheme of the regulator is given in the Appendix No.8.The regulator is performed under the scheme air flow flue gases flow with nonlinear correction by the average set furnace depression.The regulator includes the ratio regulator and the adjustor. The following signals are supplied to the ratio regulator: the signal of common air flow and the signal of flue gases flow (the last one is formed as the ratio of nonlinearly transformed signal of the total capacity of ID fans to the maximum pressure produced by one of two ID fans).The ratio regulator effects on the actuating devices of the hydraulic couplings of ID fans 1 and 2 through the synchronizing system.Nonlinearly transformed signal of the depression deviation from the set value is supplied to the adjusting regulator inlet. The adjustor changes the setting to the ratio regulator air flow flue gases flow. The adjustor scheme contains the prohibition to change the output signal at the ID fan hydraulic coupling being opened in full.It is provided the operation mode with one ID fan with the signal of flue gases flow and at that the self-tuning Kn of the ratio regulator is performed.

At switching off the regulator its dynamic balancing is put in.6.4.10 Feed-Water Regulator

The regulator is designed to keep the constant level in the Boilers drum in all modes of the Boiler operation.The structural scheme of the regulator is given in the Appendix No.9.Two feed water regulators are provided: the start-up regulator and the main regulator.The start-up feed water regulator is in automatic mode and controls water supply to the Boiler through the control feed valve in the feeding bypass line according to the level setting in the start-up mode.The main feed water regulator is put into operation at change-over of boiler feeding from the bypass line into the main one. The regulator controls water supply to the Boiler by means of the control feed valve in the main line according to the level setting in the main operation mode. Change-over from the ignition feed water regulator to the main one is performed automatically.The main feed water regulator is performed with the main signal of the actual level in the Boiler drum (with the drum pressure correction) and derivative signals of the actual flows of the feed water to the Boiler and steam flow at the Boiler outlet (with temperature and pressure correction). Correction of the feed water regulator signals enables to improve the accuracy of the level keeping in the different modes of the Boiler operation.The ignition regulator is performed as static with input signals of the Boiler drum level and control valve position.6.4.11 Boiler Steam Temperature Regulators

6.4.11.1 Main steam temperature control

High-Pressure steam temperature control system provides the optimum conditions of heating surfaces in the boiler start conditions from the different heating states and boiler work within the load range.

For high-quality spray of the injected water and centrifugal atomizers starting injections reliable operation it is provided for automatic keeping of the feed water required pressure in the starting injections lines.

Steam temperature automatic control system consists of 3 interconnected spray regulators 1, 2, 3.

At the unit starting stage, boiler outlet steam temperature control is being made with the help of three injecting steam attemperators starting nozzles installed in each branch.

During the unit starting the boiler outlet steam temperature value is being generated at the temperature programmer depending from the initial HP cylinder temperature condition of the turbine and coming to starting regulator of the 3rd spray.

Injection regulator 2 provides 3rd injection control range, keeping the designed temperature difference. Spray regulator 1 provides 2nd spray control range, keeping the designed temperature difference.

The permission for starting injections switch on comes at pressure increase up to ~30 kgf/cm2 in the drum and for main injections switch on at pressure increase up to ~115 kgf/cm2 in the drum.

By load increasing, at steam temperature close to the rated temperature there is a transfer into main injections and starting injections gradual deactivating.

After starting injections deactivating, the spray atomizers main injections are being switched on at 1st and at 3rd spray attemperators. The 1st spray main regulator provides the 3rd spray operating range, keeping there designed temperature difference. The 3rd spray regulator stabilizes boiler outlet steam temperature.

Water for injection feeds from the feed-pump discharge pipe.

6.4.11.1.1 Spray regulator 1

Spray regulator 1 designed for operating upon starting conditions and in basic modes of the boiler operation and it actuates to starting spray control valves (CSV 1S) and main valves (CSV-1).

The structural scheme of the regulator is given in the Appendix No.10.

At starting conditions spray regulator 1 provides the 2nd spray control range, and at basic modes the 3rd spray control range.

The signal concerning the regulated steam temperature before the second injection T2 , steam temperature high-speed signal after the 1st injection steam attemperator (T1) and set point signal, forming the temperature drop on the next injection (~ 600C) come to the regulating unit of starting regulator.

If the limits concerning the steam temperature before the 2nd spray or the 2nd spray control range finishing (both for more and for less), or switching the 2nd spray regulator to remote operation occur then the 1st spray regulator is being switched to keep the temperature due to which the limits occurred. At this case, change in these regulator previous values is being frozen.

At the HP-Convention Superheater-3 outlet steam temperature close to rated temperature (> 530 0C), steam flow > 250 t/h the integrator is being connected to regulator (to reduce the values from 60 0C to 00C) and it reduces the difference at the 2nd spray gradually up to 00C due to opening CSV-1S. The 2nd starting spray control valve (CSV-2S) will be closing gradually. After its complete shutdown, the 1st spray starting regulator switches off, and the shutdown task connects to CSV-1S. Simultaneously, the actuation of the 1st spray main regulator, providing the designed temperature difference on the 3rd injection cooler of the main injection connects to the 1st spray main control valve (CSV-1).

After 2nd spray control valve (CSV-1S) is closed the 1st spray main regulator switches on.

At the regulator diagram there is provided for the 1st spray steam temperature control: this temperature must always be higher then the saturation temperature, not less then 14 0C.

6.4.11.1.2 The 2nd spray regulator The 2nd spray regulator is being intended for operation by boiler operation starting conditions only and provides the 3rd spray control range. The regulator actuates to the spray control valve CSV-2S.

The structural scheme of the regulator is given in the Appendix No.11

The signal concerning steam regulated temperature before the 3rd injection, steam temperature high speed setpoint (command) after the second injection steam attemperator (T2) and the set point, forming the temperature drop on the next injection (~ 600C) comes to the regulator inlet.

If the limits concerning the steam temperature before the 3nd injection or the 3rd injection control range finishing (both for more and for less), or switching the 3nd spray regulator into remote operation occur then the 2st spray regulator is being switched to keep the temperature due to which the limits occurred. At this case, change in these regulator previous values is being frozen.

When the 2nd injection is out of operation (CSV-2S shutdown) the command for shutdown of all nozzles shutoff valves and the 1st,3rd starting spray control valves is being formed at the regulator diagram.

Two regulators are being provided for the boiler.

6.4.11.1.3 The 3rd spray regulator The 3rd spray regulator is being intended for operation within starting conditions and at the basic modes of the boiler operation, it actuates to starting (CSV-3S) and a main (CSV-3) spray control valves and keeps the boiler outlet designed steam temperature.

The structural scheme of the regulator is given in the Appendix No.12.

Starting regulator keeps designed main steam temperature, feeding into turbine and ensures its safety warm up during the starting process.

The signals come to the regulator inlet it concerns the boiler outlet steam regulated temperature (Tb) the speed of the steam temperature change after injection (T3) and setpoint. The setpoint for the starting regulator is being formed by the temperature programmer.

After the 2nd starting injection shutdown, the setpoint for shutdown comes to CSV-3S. At the same time, the 3rd spray main regulator actuates to the main control valve CSV-3.

Two regulators are being provided for the boiler.

6.4.11.2 Reheat steam temperature Control

Reheat Steam Control System ensures the optimal condition of the heating surfaces and boiler outlet reheat temperature within the conditions of the boiler starting from the different thermal conditions and boiler operation within the load range.

The automatic keeping of the feed water required pressure at the starting injections line.

At the unit starting stages, reheating steam temperature the regulating at the boiler outlet is being made with the help of two injection steam attemperators starting nozzles installed in each branch. Water for injections in this mode is being supplied from the feed pump pressure line.

The steam temperature control system consists of two interconnected spray regulators 1, 2.

Boiler outlet steam temperature setpoint at the unit starting, forms in temperature programmer depending from the turbine IP-cylinder temperature condition and comes to the 2nd spray starting regulator.

The 1st spray regulator provides for the 2nd spray regulating range, keeping the designed temperature difference.

With the load increase, at the steam temperature close to rated temperature there is a transition to the main injections and gradual deactivation of all starting injections.

The permission for connecting starting injections to reheater comes by approaching the pressure level ~ 8 kgf/cm2 at the reheater outlet.

After starting injections deactivation the main injections are being switched on at the 1st injection steam attemperator. The 1st spray regulator stabilizes the boiler outlet steam temperature.

The water supply regulating at starting conditions is being made in the way of starting regulators actuation to their control valves.

After each starting spray control valve, before each centrifugal atomizer, shutoff valve is being installed for the purpose of switched on nozzles quantity change.

Reheat steam temperature regulating at the boiler operation main conditions is being made in the way of steam bypassing through the main steam reheater control valve installed at circuit inlet and water injection into steam attemperator 1, installed before the LPConvection Superheater.

Water for injection at this condition is being supplied from the feed pump intermediate stage.

.

6.4.11.2.1 The 1st spray regulator to reheater

The 1st spray regulator into reheater is being intended for operation at starting conditions and basic modes of boiler operation, it actuates to starting (CSV-1RS) and main (CSV-1R) spray control valves.

The structural scheme of the regulator is given in the Appendix No.13.

At the starting conditions the 1st spray regulator provides for the 2nd spray regulating range, keeping there designed temperature difference.

At the approaching to the conditions of the starting spray shutdown that are being formed in the 2nd injection regulator diagram and complete shutdown of CSV-2RS the 1st spray starting regulator is being switched off and the shutdown setpoint comes to CSV-1RS. Simultaneously, the actuation of the 1st main regulator is being connected to the 1st spray main control valve (CSV-1R).

The 1st spray main regulator serves to prevent an unavailable reheater outlet steam temperature increase at finishing steam bypass regulating range.

The regulator actuates to the control valve CSV-1S. The regulator is being turned in the designed temperature value, which is 10 0C higher of its nominal value and as the reason of it usually the regulator in holding condition keeping its control valve in the complete shutdown position.

The regulator receives following signals: superheater outlet steam temperature TLP CSH, derivative of the temperature after injection T1R and nonlinearly converted signal according to the steam bypass control damper position Gsb-cd. This signal is used to increase the regulator operation efficiency.

Nonlinear element is being turned so that the setpoint at its outlet appears only by approaching to the opening degree of steam bypass control valve up to 80 % of full running and at the further opening of damper valve the setpoint increases, reducing the task for 1st spray regulator on 7-8 0C in comparison with the initial value at the full opening Steam Bypass Control Damper.

Due to the setpoint reducing, the 1st spray regulator gets into operation and keeps steam temperature at the lower level.

6.4.11.2.2 The 2nd spray regulator into preheaterThe 2nd spray regulator is intended for operation at the boiler operation starting conditions only and actuates to the control valve, to the spray CSV-1RS.

The structural scheme of the regulator is given in the Appendix No14.

The 2nd spray regulator keeps the designed reheating steam temperature feeding into turbine, ensuring its safety warm up at starting operations in accordance with the setpoint forming in reheating steam temperature programmer.

At the LP-convention superheater outlet steam temperature close to the rated temperature (>540 oC), steam flow > 460 t/h the 1st spray starting regulators switched on and steam bypass, to the CSV-2RS connects the task for its shutdown.

6.4.11.2.3 The reheater steam bypass regulator

The regulator is intended to keep the designed steam temperature value at the steam preheater outlet in the operation boiler basic modes.

The structural scheme of the regulator is given in the Appendix No15.

The signals concerning the regulating temperature TLP CSH and its time derivative, derivate signal of the blend temperature Tsm after main steam reheater bypass and setpoint (Tsp).

The regulator actuates to the bypass control damper of the main steam reheater.

6.4.12 Control of the Boiler Feed Water PumpsThe structural scheme of the regulator is given in the Appendix No.16.Capacity of each feed water pump is effected by shifting the actuator of the hydraulic coupling.The controlled parameter for the feed water pump capacity regulator is water pressure differential at the feed control valve.Each of three feed water pumps capacity is controlled in such a way to keep the pressure differential at the feed control valve within the set limits.At that the set ratio of feed water pressure and flow is observed.The function f(x) determines the design pressure for the current feed water flow.The following limitations are provided:

- maximum pressure in the main feed water line;

- minimum admissible feed water flow.6.5 Structure of process parameters changing systemMainly the sensors with analogue output are used in the Unit control system.

The signals used for automatic control have double redundancy and the signals used for process protections of the Unit and the Boiler have triple redundancy.The control and monitoring system should provide the following:

- average value of the controlled parameter;

- control of deviation between the average value and each value of the sensor signal;

- control of deviation value and delay time;

- automatic disconnection from operation the disabled sensor with corresponding alarming;

- possibility for operator to select or disconnect measuring sensors from operation.7. Start-Up Procedures7.1 Start-up timeThe time required to reach the Turbine start-up parameters is determined by the permissible pressure, temperature and load gradients of the steam generator. The required steam parameters to start-up the Turbine depend on the Turbine metal temperatures before start-up.After Turbine start-up and synchronization the further load increase is determined by the permissible pressure, temperature and load gradients of the steam Turbine.The maximum time of the Unit start-up from the moment of the command for the Boiler purge (ventilation) up to reaching the rated output electrical power (full load) is the following:

Cold Start-Up (shutdown >150 h).. 9.67 h;

Warm Start-Up (shutdown