krishnapatnam i&c training r1 part1

© 2012 MITSUBISHI HEAVY INDUSTRIES, LTD. All Rights Reserved.

Training for Steam Turbine Control

Krishnapatnam Thermal Power Project, 2 X 800 MW

22 May. 2013

NAGASAKI CONTROL SOLUTIONS SECTION

INSTRUCTOR: AKIRA ISHIGAKI

© 2012 MITSUBISHI HEAVY INDUSTRIES, LTD. All Rights Reserved. 2

1. SYSTEM CONFIGURATION

2. TURBINE CONTROL SYSTEM (TCS)

3. TURBINE AUXILIARY EQUIPMENT CONTROL

4. TURBINE PROTECTION SYSTEM (TPS)

5. TURBINE SUPERVISORY INSTRUMENTS (TSI)

6. ATS (Automatic Turbine Start-up)

7. TURBINE SHUT-DOWN

Contents

Contents



Abbreviations

System Configuration

Abstract of System Configuration

Network Interface

Functional Overview

System Configuration



OPS : Operator Station ACS : Accessory Station (For Trend-data archive) EMS : Engineering & Maintenance Station MPS : Multiple Process Station OPC Server : OLE (Object Linking & Embedding) for Process Control HDS : Historical Data Server TSI : Turbine Supervisory Instrument TPS : Turbine Protection System TCS : Turbine Control system

ABBREVIATIONS


1. SYSTEM CONFIGURATION OPS

EMS

ACS

TCS TSI TPS

Data Collection System

OPC Server

HDS

MPS MPS MPS MPS


Abstract of System Configuration

OPS ACS

EMS MPS

Ethernet (100Base-Tx)

Control Net

I/O Adapter

TCS

Local Instruments



Network Interface

EMS/OPS/ ACS

Control-Net (5 Mbps)

A B

System I/O Interface

System I/O Interface

CPU-A

CPU-B

Ethernet-A1 Ethernet-A2

Ethernet-B1 Ethernet-B2

HUB

HUB

A

Local Network Interface

B Network Adapter I/O Module

A B

Network Adapter I/O Module

PT TE Valve

Local

A B

Local Network Interface

1-2. SYSTEM CONFIGURATION


Sample: CPU Chassis

9

System DIO

Control Net EthernetA-1/2

CPU Power Supply-1/2

A B

CPU-A

Sample

1-2. SYSTEM CONFIGURATION

Human-machine interface for plant operation and monitoring.



Operator Station (OPS)

FUNCTIONAL OVERVIEW

Engineering tool for performing system configuration, creation and modification of control logic, graphic displays, trends and control loop plates.

Engineering & Maintenance Station (EMS)

Digital controller used to perform automatic turbine control and protection and features advance capabilities that support high-speed processing such as Turbine governor control and protection interlocks.

Multiple Process Station (MPS)

Storage for long-term data archives.



Historical Data Server (HDS)

PC for data storage into media devices. Data Management System

For communication interface between TCS and Plant-DCS. OLE for Process Control (OPC) Server

FUNCTIONAL OVERVIEW

Performs data logging and data archives such alarms, events and trend graphs.

Accessory Station (ACS)


2. TURBINE CONTROL SYSTEM

2. TURBINE CONTROL SYSTEM (TCS)



TCS Control Area

TCS Special Function Modules

Relation between TCS Special Function Modules

TCS Control Functions

Turbine Control System (TCS)


2. TURBINE CONTROL SYSTEM TCS Control Area MSV, GV, RSV and ICV are controlled in TCS for: Turbine Speed Control APC Link (Load Control by Turbine Master)

HP/IP LP

Cross Over Piping

HRH (LH)

HRH (RH)

MS (RH)

MS (LH)

RSV

RSV

ICV

ICV

MSV

MSV GV

GV

Governor Valves controlled by TCS

ICV

ICV

GV

GV



TCS Special Function Modules

EOST (Electrical Over Speed Trip detection) Module Speed detection for Turbine speed control EOST (Electrical Over Speed Trip:111%) detection

OPC (Over speed Protection Controller) Module OPC detection (Combined Curve)

TCL (Turbine valves Closing Logic) Module Closing turbine valves with fast speed Interface with SVL and OPC modules

Following Special Function Modules are equipped in TCS cabinet :

SVL (Servo Valve interface (LVDT feedback) ) Module Send electrical signal to Servo Valve Receive LVDT position signal as feedback.



Valve Demand

TCS Hardware

P T

0%

Local

High Press. Oil

Position Feedback Signal

(0～100%)

Governor Valve

TCS Software Logic

Position Feedback

Forced Close

Command (From TCL

Module)

Software Signal 0～100%

Valve Demand -50～+50mA

LVDT Signal (Voltage)

Servo Valve

LVDT Δ

－

＋

TCS Special Function Module: SVL Module Electric signal from TCS (SVL module) is converted to Hydraulic signal by Servo Valve

Linear Variable Differential Transformer

SVL Module

LVDT Interface



SVL (A)

SVL (B)

Double Redundant SVL module applied to each Servo Valve.

Reference:

Detailed Schematic Diagram is available in Drawing No. 66400-7021 “Schematic Diagram For TCS And Turbine Communication Equipment Cabinet”.

SVL (A)

SVL (B)

Servo Valve

Schematic Diagram TCS Special Function Module: SVL Module

LVDT



Sample: Servo Valve Actuation

From SVL Module (-50mA to +50mA)



TCS Hardware TCS Software Logic

TCS Special Function Module: TCL Module Executes the interlock logic with high response time for quick closing of governor valves.

TCL Module

OPC-1 TEST MODE

Parallel Operation (52G CLOSE)

TURBINE TRIP

SPEED ABNORMAL

OPC-2 TEST MODE

OPC-3 TEST MODE

OPC-1 Operated (from OPC module)

MSV CLOSE COMMAND (To SVL Module)

GV/ICV CLOSE COMMAND (To SVL Module)

OPC OPERATED

Local

S

OPC SV (Open) OPC-2 Operated

(from OPC module)

OPC-2 Operated (from OPC module)



Reference:


Schematic Diagram TCS Special Function Module: TCL Module

TCL -A, B


2. TURBINE CONTROL SYSTEM Relation between TCS Special Function Modules

Software

Logic

(MPS)

･Speed detect

･EOST detect

Speed Pick Up×3

SVL Module×10×2

Servo Valve

LVDT

･Interlock Logic

･OPC 2 out of 3

TCL Module×2

Over Speed Protection

OPC Module×3

Generator MW

IP Inlet Steam Press.×3

Generator Current×3

Gen. Parallel Operation

EOST Operated

Forc

ed C

lose

C

omm

and

To TPS (Interlock)

TCS Panel

Turbine Tripped OPC

Solenoid

OPC Operated

PT

CT

MW

Speed

Control Demand

-50～+50 mA EOST Module×3

OPC Operate Command

Valve Demand Conversion


2. TURBINE CONTROL SYSTEM Sample: TCS Input & Output Interface

TCS

Servo Valve

Turbine Speed×3 (For Control & EOST)

Generator MW (for monitoring, Initial Load & Runback function)

Turbine Tripped ×3

Generator Parallel Operation ×3

IP Inlet Steam Press.×3 (for OPC)

Generator Current×3 (for OPC)

MSV (LH) MSV (RH) GV (LH1) GV (LH3) GV (RH2) GV (RH4) ICV (LH1) ICV (LH2) ICV (RH3) ICV (RH4)

LVDT (ｆor each Valve)

PT

CT

MW

Linear Variable Differential Transformer



(1) Speed control

(2) Valve Transfer (MSV/GV)

(3) Initial Load Control

(4) Load Limit/ Governor Control (GOV/LL Control)

(5) Valve test function

(7) Over Speed Protection Circuit (OPC)

(8) Electrical over speed trip (EOST)

(9) Other test (MOST/OPC/EOST test) Protective Function

(6) Vacuum Unloader (VU) Runback Function

(10) Stress Control / Monitoring

(0) Turbine Start-up Curve / Start-up Mode

TCS Control Functions



Generator MW

Steam Admission

Rub Check

Heat Soak

Synchronization

Initial Load

Valve Transfer 3000rpm

2200rpm

500rpm

Speed Load

Time

100%

(0) Turbine Start-up Curve

Turbine Speed


Control Stage Outlet Metal Temp


(0) Turbine Start-up Mode Start-up mode is determine based on Control Stage Outlet Metal Temp. START-UP

MODE Control Stage

Outlet Metal Temp COLD < 120℃ WARM 120℃ ~ 350℃ HOT 350℃ ~ above


Speed Control


(1) Speed Control

Generator MW

Steam Admission

Rub Check

Heat Soak

Synchronization

Initial Load

Valve Transfer 3000rpm

2200rpm

500rpm

Speed Load

Time

100%

Turbine Speed


Speed Control Demand

Speed Control (before valve transfer) is performed by MSV. All GVs are full opened.

Full Open Bias is added.

Bias is zero.

Full Open (No Control)

Control

Control


Governor Control Signal Flow

(1) Speed Control

GV Demand

ICV Demand

MSV Demand



EOST Module

Speed Detection

MED

SG

SG

SG

T

T

Speed Setter

3000

500

0

V> △ P

SG

SG

T

T Hold

Speed Rate

300rpm/min

0rpm/min

Fx SVL Module

MSV

Hard Ware Field

Hardware Field

①

②

③

Time

Act. Speed ②

Speed Ref. ①

③

Speed Target

2200

T

T SG

SG 150rpm/min 150

300

LVDT

3000rpm

2200rpm

500rpm

0rpm

(1) Speed Control



(1) Speed Control

Turbine Speed & Speed Rate operating window

2200



(1) Speed Control

<Critical Speed Area>

640 ~ 760 rpm

1090 ~ 1760 rpm

1890 ~ 2060 rpm

2390 ~ 2710 rpm

TCS prevents the Turbine running near

the critical speed

Turbine Speed & Speed Rate control plate

2200 rpm



(2) Valve Transfer

Valve Transfer Generator MW

Steam Admission

Rub Check

Heat Soak

Synchronization

Initial Load

3000rpm

2200rpm

500rpm

Speed Load

Time

100%

Turbine Speed Valve Transfer


Posi

tion

Time

GV : Full Open

Valve Transfer

MSV Control

MSV : Full Open

GV Control

Speed Up Complete

After turbine speed up completed, turbine control mode is transferred from “MSV control mode” to “GV control mode”.

GV Open Bias becomes Zero


(2) Valve Transfer

MSV Open Bias maximum


MSV Valve Transfer Bias

GV Valve Transfer Bias To Zero

To Maximum

Control

Control


Control


(2) Valve Transfer




(2) Valve Transfer

Valve Transfer operating window

2200



(2) Valve Transfer Valve Transfer

control plate

2200 rpm


Before Synchronization


Load Generator MW

Steam Admission

Rub Check

Heat Soak

Synchronization

Initial Load

3000rpm

2200rpm

500rpm

Speed

Time

100%


(3) Initial Load Control (Before Synchronization)

Control


Before synchronization, speed Inc/Dec signals come from GCP (Generator Control Panel) (Auto / Manual Synchronization operation) and added to GOV Set Circuit.

GCP Speed Inc/Dec command

(3) Initial Load Control (Before Synchronization)

Control




Initial Load Control


Generator MW

Steam Admission

Rub Check

Heat Soak

Synchronization

Initial Load

3000rpm

2200rpm

500rpm

Speed Load

Time

100%


(3) Initial Load Control

Control

Control


2. TURBINE CONTROL SYSTEM (3) Initial Load Control

Initial load control is started when Circuit Breaker is closed. (5% of Rated MW as initial load).

Initial Load Control Demand

+

+


Load Control (by Turbine Master)

Generator MW

Steam Admission

Rub Check

Heat Soak

Synchronization

Initial Load

3000rpm

2200rpm

500rpm

Speed Load

Time

100%


2. TURBINE CONTROL SYSTEM Load




During the load operation, GOV/LL mode can be selected.


Control

Control




GOV Mode (Frequency Compensation)

LL Mode (Load Limiter : Load Maintain)

GV Control Demand is determined by

“Load Demand” + “Frequency Compensation (DROOP)”.

GV Control Demand is determined by

“Load Demand” only.

Auto Follow Mode GOV mode + LL Auto Follow : LL demand is X% higher than GOV demand.

LL mode + GOV Auto Follow : GOV demand is X% higher than LL demand.

X% : Auto Follow Bias (Default : 5%)


(4) Load Control (GOV/LL Control)


Frequency Compensation (DROOP)

Droop is applied for Frequency Regulation after Synchronization.

Droop is normally 4%.




B C

E D

A

a b

c

Power Supply Power Consumption

50Hz

d

e




B C

E D

A

a b

c


50Hz

d

e



f g h i


B C

E D

A

a b

c


50Hz

d

e




B C

E D

A

a b

c


50Hz





50Hz



B C

E D

A

a b

c d

e


Δrpm (ΔHz)

Droop Bias [%]

3120rpm (52Hz) 2880rpm (48Hz)

Droop 4% 3000 x 0.04 =120

100%

- 100%


Droop Bias



GOV/LL Mode Switchover

△

3000rpm (50Hz)

MW

MWD

PI <L

＋

△

FX

Turbine Speed

Droop

Turbine Master Controller ＋

SG 5% Auto Follow

LL mode signal

GOV mode signal 100%

Droop 4% Droop Bias%

rpm(Hz)

-100%

Coordination Control Circuit - DCS



GV

3000rpm (50Hz)

2880rpm (48Hz)

3120rpm (52Hz)



GOV/LL Mode Switchover (4) Load Control (GOV/LL Control)

Demand (%MW)

Time

LL

GOV

LL MODE GOV MODE GOV/LL Manual

- LL mode - GOV Auto Follow

- GOV mode - LL Auto Follow

Turbine Master Demand GOV/LL Reverse

GOV/LL Reverse

5% of Auto Follow (LL Auto Follow Rate: 100%/min)


Switched

Parallel Mode

GV Lift

GV#1 ~ #4

Load

Sequential Mode

GV#1, 4 #2,3

GV Lift

Load


Valve Management (Sequential / Parallel Mode Switchover)

(4) Load Control

Parallel Mode

GV

Lift

GV#1 ~ #4

Load

Sequential Mode

GV#1, 4 #2,3

GV

Lift

Load


1. Sequential Mode is applied as default mode for steam flow controllability. 2. In some case, at Sequential Mode, there is large difference in valve positions. Mode is change-over to Parallel mode to obtain more efficient operation.

Expected valve positions (as per design) at 30% Pressure Sliding condition.

Actual valve positions at 30% Pressure Sliding condition.

Valve positions after change-over


(4) Load Control Valve Management (Sequential / Parallel Mode Switchover)



(4) Load Control

Valve Management operating window

Load Control operating window

2200

Control

Control



Bias is added for minus (-) direction during the valve test. Testing of Valves are divided into 2 groups as HP/IP group.


(5) Valve Test


The valve test is perform to confirm the movement of valves (MSV and GV) during load operation. Before the test, TCS MW Control IN mode and APC Link-out should be selected, Gen. load is >50% and GV positions are >28%. Partial stroke test is applied to minimize main steam pressure loss and load fluctuation.

MSV(LH) MSV(RH)

0%

GV#1 GV#3 GV#2 GV#4

100%

GV Position

80%

GV Pos.-10%

TEST RESET

MSV (LH) TEST START TEST

COMPLETE

GV#1 TEST START

TEST RESET

TEST COMPLETE

Note: Individual Test for each HP valve


(5)-1 HP Valve Test


The valve test is perform to confirm the movement of valves (RSV and ICV) during load operation. Before the test, TCS MW Control OUT mode and APC link-out should be selected, Gen. load is <100% and ICV positions are >90%. Full stroke test is applied since the influence on load fluctuation is relatively small compared to HP steam line.

0%

100%

Note: Individual Test for LH and RH © 2012 MITSUBISHI HEAVY INDUSTRIES, LTD. All Rights Reserved. 57

(5)-2 IP Valve Test

ICV (LH)

RSV/ICV (LH) Test Start

RSV (LH) Test SV Open

RSV (LH)

RSV (LH)

ICV (LH)

RSV (LH) Test SV Close

RSV/ICV (LH) Test Complete

Valv

e P

ositi

on

ICV (RH)

RSV/ICV (RH) Test Start

RSV (RH) Test SV Open

RSV (RH)

RSV (RH)

ICV (RH)

RSV (RH) Test SV Close

RSV/ICV (RH) Test Complete



(5) Valve Test

Valve Test operating window



(5) Valve Test Valve Test control plates


When the condenser vacuum is lower than the preset value, Vacuum Unloader is initiated and decreases the generator output load to maintain the vacuum. Runback rate is 10%/min (to be adjusted at commissioning stage).

Condenser Vacuum

Load (%) 25% 100%

Vacuum Unloader Operate Area

-0.846 bar

(639mmHg) (ANN)

-0.667 bar

(500mmHg) (TRIP)

Vacuum Unloader Operated

Operation Point


(6) Runback Function: Vacuum Unloader (VU)



(6) Runback Function: Vacuum Unloader (VU)

Vacuum Unloader operating window

Vacuum Unloader control plate

2200


Protective Functions

(7) Electrical Over Speed Trip (EOST)

(8) Over Speed Protection Control (OPC)

(9) Test Functions (MOST/OPC/EOST)

(10) Stress Control / Monitoring




(7) Protective Function: Electrical Over Speed Trip (EOST) Speed Pick-up Voltage is converted into rpm by EOST module. EOST contact is sent to TPS interlock circuit to make turbine trip.

Detecting Target of Turbine Rotor

(60 Teeth)

Electro-Magnetic Pick-up (Voltage Signal)

EOST MODULE -A

H/L

H/L

H/L To

TPS

TCS

EOST MODULE -B

EOST MODULE -C

Wave Count

rpm

Wave Count

Wave Count

> 3330rpm

Speed Control

EOST

Speed Control

Speed Control

> 3330rpm EOST

> 3330rpm EOST

rpm

rpm



Schematic Diagram

Reference:


(7) Protective Function: Electrical Over Speed Trip (EOST) EOST -A, B, C



When turbine speed exceeds 107% of rated speed or load unbalance between required generator output and turbine input (IP turbine inlet steam pressure – generator current), OPC is initiated to prevent the over speed trip.

RPM

△MW(%) = IP Inlet Press (%) - Generator Current (%)

107 % (3210 rpm)

30% 60%

OPC Operating Zone

No Action

What is OPC Function ?

△MW(%)

(8) Protective Function: Over Speed Prot. Control (OPC)



OPC Operate Function

100

107

Speed(%)

0 30 60

OPC Operate

Load Unbalance(%) (IP Inlet Steam Press – Gen. Current)

OPC Module x 3

2/3

Forced Close Command To SVL Module (GV/ICV)

TCL Module x 2

Turbine Speed-1 Turbine Speed-2 Turbine Speed-3

IP Inlet Steam Press-1 IP Inlet Steam Press-2 IP Inlet Steam Press-3

Generator Current-1 Generator Current-2 Generator Current-3

(3210rpm)

S OPC SV

When OPC condition is detected, OPC module outputs “OPC Operated” signal to TCL module. TCL module makes OPC Solenoid Valves “Energized” (open) by 2 out of 3 logic to make GV/ICV closed.




OPC -A, B, C Schematic Diagram

Reference:





MOST test

OPC Module test / OPC Actual Test

EOST Module test

Test functions for protective device and Special Function Modules are available in TCS as follows:

(9) Protective Function: Test Functions



To confirm actual Turbine trip by MOST (Mechanical Over Speed Trip) by manually increasing the Turbine Speed until above MOST setting of 110% (3300rpm).

Test is possible while turbine is at Rated Speed and at No Load condition.

1. Confirm Turbine is operating at 3000rpm and unsynchronized

2. Call “MOST Test“ control plate.

3. Select MOST Test mode “IN”.

4. Increase turbine speed gradually.

Purpose

Procedure

(9) Test Functions : MOST Test



(9) Test Functions : MOST Test

MOST Test control plate

MOST Test operating window

During MOST Test “IN” mode, the following changes applies automatically: • GOV SPEED SET upper limit from 106% (3180rpm) to 112% (3360rpm). • EOST setting from 111% (3330rpm) to 112% (3360rpm) . • OPC Function is out of service.



Purpose To confirm the function of each OPC Module without actual closing of GVs and ICVs.

During the test, a test bias signal is sent to the OPC module and confirm if the OPC operated signal will be generated.

Test is perform in one of the three modules at a time while turbine is at No Load condition.

(9) Test Functions : OPC Module Test



(9) Test Functions : OPC Module Test

OPC Test operating window

OPC Test control plate

1. Confirm Turbine is unsynchronized. 2. Call “OPC Test“ control plate (SPEED or LOAD). 3. Select “TEST” PB. 4. Select “FIX” or “VARIABLE” mode. If FIX mode is selected, a fixed value setting will be simulated. If Variable mode is selected, set point can be increased by control plate.

Procedure



To confirm the complete operation of OPC function.

Test is perform to all the three modules to actuate the OPC solenoid valves that will close the GVs and ICVs.

Test is possible while turbine is at No Load condition .

(9) Test Functions : OPC Actual Test

Purpose



(9) Test Functions : OPC Actual Test

OPC Actual Test operating window

OPC Actual Test control plate

1. Confirm Turbine is unsynchronized. 2. Call “OPC ACTUAL TEST“ control plate. 3. Select OPC Actual Test “IN” mode. 4. Select OPC Actual Test “ACTUAL COMMAND”.

Procedure



Purpose To confirm the function of each EOST Module without actual Turbine trip.

During the test, a bias signal is added to the Turbine speed and confirm if the EOST operated signal will be generated by EOST module with a setting of 111% (3330rpm).

Test is perform in one of the three modules at a time while turbine is at Rated Speed and No Load condition.

(9) Test Functions : EOST Module Test



(9) Test Functions : EOST Module Test

EOST Test operating screen

EOST Test control plate

1. Confirm Turbine is unsynchronized. 2. Call “EOST Test“ control plate. 3. Select “TEST” PB. 4. Select “FIX” or “VARIABLE” mode. If FIX mode is selected, a fixed value setting (11%) will be simulated. If Variable mode is selected, set point can be increased by control plate.

Procedure


In order to reduce the stress on the turbine, the mismatch value between rotor average temperature and first stage steam temperature is calculated. Based on this mismatch, the Turbine speed up rate and load increase rate are controlled.

△T = (First Stage Steam Temp) – (Calculated Rotor Average Metal Temp)

TURBINE SPEED

STRESS CALCULATION

MAIN STEAM TEMP.

MAIN STEAM PRESS.

HP TURBINE INLET STEAM PRESS. CONTROL STAGE OUTLET METAL TEMP.

△T


(10) Protective Function: Stress Control / Monitoring


Turbine speed up rate is controlled except during critical speed.

SPEE

D

Time

△T > 60 degC

△T < 60 degC

Speed up operation

△T = (First Stage Steam Temp) – (Calculated Rotor Average Metal Temp)



SPEED RATE HOLD


TURBINE SPEED

STRESS CALCULATION

MAIN STEAM TEMP

MAIN STEAM PRESS

HP TURBINE INLET STEAM PRESS

CONTROL STAGE OUTLET METAL TEMP

△T

H/L

X X

SG SG

STRESS LIFE TIME

CONSUMPTION CALCULATION

H/L

±60 ℃

52G CLOSE

NOT TURBINE TRIP

STRESS OPERATE SIGNAL (For Load Control Logic in Plant-DCS)

Stress Life Time Consumption Calculation Function Stress Operate Signal (for Load Rate Change in Coordination Control)



Stress Control “IN” mode


Calculation Scheme

△T






2200


3. TURBINE AUX. EQUIP. CONTROL

3. TURBINE AUXILIARY EQUIPMENT CONTROL

krishnapatnam i&c training r1 part1

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