hitachi_r2005_03_111

Hitachi Review Vol. 54 (2005), No. 3 145

New-generation Integrated Monitoring and Control System

OVERVIEW: Hitachi delivered a new-generation integrated monitoring andcontrol system to Shanghai Municipal Electric Power Company’sWaigaoqiao Power Station in Shanghai, China. Built around the HIACS-5000M (Hitachi Integrated Autonomic Control System-5000M), the systemnot only provides a powerful supervisory, operation, and control system forpower plant equipment, it also supports enhanced plant operating efficiencyand power plant management operations. Enhanced reliability andmaintainability go without saying, but the system also introduces significantlymore advanced capabilities for manipulating information that supportsimproved plant operation efficiency and better management capabilitiesfor dealing with the liberalization of electric power transactions and sales.This power plant is a 900-MW large-capacity coal-fired supercritical plant,and is intended to serve as a model for future thermal power plantconstruction in China.

Shigeru Takahashi

Satoru Shimizu

Takaaki Sekiai

INTRODUCTIONSHANGHAI Municipal Electric Power Company’sWaigaoqiao Power Station Units 1 and 2 begancommercial operation on April 20 and September 22,2004, respectively. The two 900-MW large-capacity

supercritical coal-fired power plants were built withfinancial assistance from The World Bank Group.Turbines, generators and a boiler for the plant weresupplied by German manufacturers, and the I&C(instrumentation and control) system was supplied by

Fig. 1—Inside of Central Monitoring and Control Room Set up for New-generation IntegratedMonitoring and Control System.All monitoring and control equipment and functions for two plant units are centralized in onecontrol room featuring large-screen displays.

New-generation Integrated Monitoring and Control System 146

Hitachi. In China as elsewhere, greater demands arebeing placed on I&C systems. In addition tosupervisory, operation, and control capabilities, clientsare also demanding more advanced capabilities formanipulating information that supports improvedoperating efficiency, better plant managementoperations, and other capabilities. Even in terms ofcontrol performance specifications, the requirementsof the Waigaoqiao project were more exacting thanthe required performance specifications of Japan.

OVERVIEW OF NEW-GENERATIONINTEGRATED MONITORING AND CONTROLSYSTEM FOR WAIGAOQIAO POWERSTATION

The integrated monitoring and control systemconsists of a DCS (distributed control system) thatmonitors and controls the plant status, a SIS(supervisory information system) that keeps the plantoperating at peak efficiency through optimal loaddistribution of each plant unit, an MIS (managementinformation system) that supports management

operations with a full range of office automationfunctions including management, recording, searchingplant data, management of documentation, e-mail,electronic bulletin-board capabilities, and more. Theplant simulator system that is linked to plant datavia the MIS, and various plant subsystems such asthe water treatment system and a coal-handlingsystem.

All of these systems are interconnected by a high-speed large-capacity network enabling centralizedmonitoring by the DCS, and all constituent functionsand systems to organically interwork (see Fig. 2).

FEATURES OF NEW-GENERATIONINTEGRATED MONITORING AND CONTROLSYSTEMDCS

A DCS is the heart of a power plant’s I&C system,and for this, we used Hitachi’s HIACS-5000M, whichhas proven to be very effective in plant installations inJapan and throughout the world. The proposed HIACS-5000M has the following features:

Fig. 2—Overall System Configuration of the New-generation Integrated Monitoring and Control System.All DCSs, SISs, MISs, and subsystems are organically interconnected by a high-speed, large-capacitynetwork.

NCS ADS

Supervisory informationsystem

Unit 1 DCS

Management informationsystem

Simulator system

Subsystem(1)

Subsystem(8)

Controlstation

Instructorstation

Engineer stationfor simulator

Man-machine interface

Controller

DCS operatorstation × 6 sets

DEH operatorstation × 2 sets

Localoperatorstation

× 2 DCS

Engineerstation

DEH

I/O system

Gateway

µ∑NETWORK-100

Duplicatedserver

Terminalsfor operation

Server ×10 sets

PC × 20 sets

5 sets

Coal yard Out of scopeOut of scopeOther system

Process model computer

2 sets

• Internet• SMEPC

: Data link: Hardwired

CB A

CBA

Subsystem(1)

Subsystem(16)

Subsystem(1)

Subsystem(8)

Common DCSMan-machine interface

NCS: network computer and monitoring control systemADS: automatic dispatch system

DEH: digital electro-hydraulic control system I/O: input and outputSMEPC: Shanghai Municipal Electric Power Company

Controller

Gateway

µ∑NETWORK-100

Unit 2 DCSMan-machine interface

Out of scope

Controller

Gateway

µ∑NETWORK-100

Exchanger Exchanger Exchanger

Router

Fire wall

Controller

Largescreendisplay

I/Osystem

Electricalcontrolpanels

Gateway Gateway


in dealing with abnormalities in the electric powersystem.

Supervisory Information System, ManagementInformation System, and Simulator

For convenience in carrying out actual operations,domestic Chinese manufacturers supplied thesesystems.

The SIS carries out processing and managingrealtime data from the equipment at the plant’s sixexisting units, also calculates performance, monitorsperformance, analyzes the economic factors, andenforces the optimum load distribution of each unit.

The MIS creates an open database using the datacollected in real time by the SIS, and also supportsenterprise resource capabilities as well as data storageand retrieval functions. Central plant management hasaccess to this information and uses it to supportpolicy—and decision—making for the plant. Thesystem is also capable of generating electric powerrate estimates supporting future power transactions andsales, and exchanging information not only within theplant but with the Shanghai Municipal Electric PowerCompany and government agencies as well.

The simulator is capable of simulating all processesof a 900-MW capacity supercritical plant with a highdegree of accuracy. In addition, control system softwareand new application software when equipment isupgraded or modified can be directly uploaded to thesimulator with all changes immediately reflected bythe simulator without additional programming. Thesimulator is capable of simulating any and everyprocess controlled from the central control room on aone-to-one basis, and thus is extremely effective fortesting and trying out operator actions, improvedincident processing capabilities, and control systems.

CONTROL TECHNOLOGIES THAT SATISFYOTHER COMPANIES’ BOILER CONTROLAND MORE RIGOROUS CONTROLPERFORMANCE STANDARDSOverview

Let us next take a closer look at Hitachi’s controltechnologies. The boilers used for the Waigaoqiaoproject are structurally very different from the boilersmanufactured by Hitachi. In addition, the boiler controlscheme provided by the client was also very differentfrom Hitachi’s conventional approach. Fig. 3 summarizesthe key differences.

At the same time, the control performancespecifications stipulated in the purchase agreement

(1) The CPUs (central processing units) supportingthe DCS are thoroughly distributed and areimplemented in a double redundant configuration toensure safe and continuous operation of the plant.(2) The control network is connected to these CPUsthrough a high-speed and large-capacity opticalnetwork with a transmission rate of 100 Mbps. Becausethis network provides a loop-back function, possiblemalfunctions are avoided when cables break,communication equipment breaks down, or when othersimilar problems occur during transmission. Thus,communication can continue without a significantsystem disturbance.(3) An APS (automatic plant startup system) wasinstalled to promote plant automation. Moreover, arational and excellent operability HMI (human-machine interface) system was offered. All plantoperations can mainly be done on the HMI system,which features 70-inch × 6 multi-screens.(4) The DCS is connected to some 20 subsystemsincluding the water treatment system, the coal handlingsystem, and the fuel oil system over redundant opticalfiber lines so that all of the systems can be centrallymonitored and operated from the DCS. With thisarrangement, both plant units can be operated andmonitored by one supervisor and four operators.(5) An RTB (remote terminal block) is used for theconnection between the DCS and the field, so thenumber of cables and the cost of construction aresignificantly lower.(6) We applied a digital protection system withHitachi’s dedicated module for boiler protection. Thededicated module is triple redundant with each systemseparate and independent so that the protectivefunctions will not be lost in the event of a single failureor malfunction. Thus, high reliability andmaintainability is ensured. The trip causes are inputto a trip interlock in each dedicated module, and theoutput trip signals from each dedicated module areinitiated through 2 out of 3 logic trip circuits. Thus, itsreliability is also guaranteed.(7) Hitachi’s experience with super critical pressureplant control has proven useful with controltechnology. Therefore, the response to the demand forelectric power systems has been improved. Runbackand FCB (fast cutback) functions are applied to preventabnormalities from being generated in the plantequipment and the electric power system. Thesefunctions were verified to be effective in thecommissioning test. The FCB function was firstsuccessfully applied in China. It led to an improvement


were extremely rigorous. According to thespecifications, for example, the permissible value forthe main steam pressure control deviation at a 3% perminute load change is ±0.2 MPa, and the permissiblerange for main steam temperature control deviation iswithin +8°C and –5°C. By comparison, the usualguaranteed performance specifications at commercialthermal power plants in Japan are ±0.8 MPa for themain steam pressure control deviation, and +8°C and–14°C for the main stream temperature controldeviation. Hitachi was able to meet this challenge byleveraging and extending its considerable expertise inplant simulation technology.

Analysis by SimulationFor this project, we started by constructing a boiler

model. The basic challenge was to develop a modelthat could simulate the characteristics of a tilting burnerthat was used in the boilers of the Waigaoqiao project.A tilting burner is essentially a method of controllingreheater steam temperature by changing the angle ofthe burner to alter the heat distribution inside thefurnace. Hitachi has never used this method, so thesimulation model had to be developed from scratch.We succeeded in developing an effective tilting burner-based boiler model by first partitioning a furnace modelfor different burner alignments so we could simulatechanges in the heat-transfer amounts attributable tovariations in the burner angle, then calculating thefurnace transient gas temperatures of each element ofthe partitioned model.

Next we investigated the control system using thenew boiler model. For this project, the basic controlscheme for the boiler was provided by the client. Foronce-through boilers of the type used in Waigaoqiaoproject, the steam temperature is determined by theratio of fuel to feedwater. Hitachi controls this ratioby changing the fuel as an indicator of steamtemperature, but the client stipulated an alternativeapproach of changing the feedwater as an indicator ofenthalpy. We considered three schemes forconstructing a master control system based on theboiler control method stipulated by the client:

Boiler follow control: generator output is controlledby the turbine, and main steam pressure is controlledby the boiler.(1) Turbine follow control: main steam pressure iscontrolled by the turbine, and generator output iscontrolled by the boiler.(2) Coordinated control: disadvantages of the boilerfollow control and turbine follow control are correctedby adding compensation to both the turbine and boilercontrol based on the turbine follow control.(3) First we incorporated the boiler control methodstipulated by the client in the simulator, then carriedout simulation analysis of different configurations ofthe master control schemes. Through the analysis wederived evaluation indices determining:(a) whether the control performance guaranteed valuewas fulfilled, or(b) which control scheme had to be adjusted in orderto fulfill the guaranteed value.

Fig. 3—Comparison of Hitachi andWaigaoqiao Project Boilers.The boilers are substantially

different in structure, combustionmethod, and control method.

Boilerstructure

Control method Water-fuel ratio control scheme Enthalpy control scheme

Hitachi’s standard

GovernorGovernor

Generator

Generator

Fuel

Fuel

XX

FeedwaterFeedwater

X-X cross-section

Turbine

Turbine

Waigaoqiao project

Twice-through type

Tilting burner

Up-downvariable angle

Fixed burner

Tower type

Corner combustionFacing combustion


Fig. 4—BoilerFollow ControlScheme.Generator output iscontrolled by theturbine and mainsteam pressure iscontrolled by theboiler.

Fig. 5—TurbineFollow ControlScheme.Generator output iscontrolled by theboiler and mainsteam pressure iscontrolled by theturbine.

Output target

Generator output

Turbine governor valve

Boiler input signalMain steam

pressure

Pressure set point

Generatoroutputcontrol

Pressurecontrol

Enthalpy set point

Superheater inlet steam enthalpy

Generator output target

Main steam pressure set point

Main steam pressure

Deviation5.2 MPa

Generator output

Reheater steam temperature

Main steam temperature

Enthalpycontrol

Fuel flowprogram

1000

800

600

400

600

580

560

540

5200 10 20 30

Time (min)

Gen

erat

or o

utpu

t(M

W)

Tem

p. (

°C)

Pres

sure

(MP)

40 50 60 0 10 20 30Time (min)

40 50 60

40

30

20

10

Feedwater flow

Fuel flow

Feedwater flowprogram

Guaranteed range

Output target

Generator output


Boiler input signalMain steam

pressure

Pressure set point

Generatoroutputcontrol

Pressurecontrol

Enthalpy set point




Main steam pressure

Deviation0.1 MPa

Deviation 158 MW

Generator output



Enthalpycontrol

Fuel flowprogram

1000

800

600

400

600

580

560

540

5200 10 20 30

Time (min)

Gen

erat

or o

utpu

t(M

W)

Tem

p. (

°C)

Pres

sure

(MPa

)

40 50 60 0 10 20 30Time (min)

40 50 60

40

30

20

10

Feedwater flow

Fuel flow

Feedwater flowprogram

Guaranteed range

We found that with the boiler follow control, thegeneration output follow performance improved duringload changes, but the changes in steam pressure andsteam temperature increased (see Fig. 4). Both theturbine follow control and coordinated control showedgood prospects that the control performanceguaranteed values could be satisfied. At the same time,we should note that one characteristic of the turbinefollow control method is that the control on generator

output is delayed (see Fig. 5). Note too that, althoughcoordinated control yields better generator outputfollow performance than the turbine control, thecoordinated control is somewhat more difficult toadjust (see Fig. 6). Table 1 compares the differences.

Having obtained simulation analysis results asoutlined above and formulated control systemadjustment guidelines through trial adjustments ofcontrol systems based on the simulation results, we


Fig. 6—CoordinatedControl Scheme.

Disadvantages of“boiler follow

control” and“turbine follow

control” arecorrected by adding

compensation toboth the turbine and

boiler contnrolbased on the

“turbine followcontnrol.”

Fig. 7—Example Trial Operation Results.Main steam pressure and temperature satisfy the controlperformance specifications as predicted by the simulationanalysis.

Output targetGenerator output

Main steam pressure

Pressureset point

Enthalpy set point




Main steam pressure

Deviation 0.2 MPa

Deviation35 MW

Generator output



Enthalpycontrol

Fuel flowprogram

1000

800

600

400

600

580

560

540

5200 10 20 30

Time (min)

Gen

erat

or o

utpu

t(M

W)

Tem

p. (

°C)

Pres

sure

(MPa

)40 50 60 0 10 20 30

Time (min)40 50 60

40

30

20

10

Feedwater flow

Fuel flow

Feedwaterflow

program

Coordinatedcontrol

Pressurecontrol

Generatoroutput control

Guaranteed range


Boiler input signal

Generator output set point

Generator output

900

800

700

600

500

Out

put (

MW

)

22

20

18

16

14

Pres

sure

(M

Pa)

560

550

540

530

520

Tem

pera

ture

(°C

)

600 MW × 820 MW (2%/min)


Main steam pressure

Main steam pressure deviation ± 0.1 MPa

Time (min)

0 10 20 30 40 50 60


Main steam temperature deviation ± 5°C

TABLE 1. Comparison of Master Control SchemesTurbine follow control or coordinated control is effective forcontrolling main steam pressure and temperature.

are now ready to conduct actual trial operationadjustment tests.

Site Commissioning ResultsIn the actual control equipment for testing, we

incorporated control circuitry for all of the controlschemes that we considered in the simulation analysisso that we could freely select whatever scheme wewanted to test. The actual trial operations were doneusing the turbine follow control scheme that was shown

Main steam pressure


Reheat steam temperature

Generator output

Generator output control

Main steam pressure control

Simulation results

Control deviation

Turbinegovernor

Boiler input

NG

5.2/–5.2MPa

3.8/–5.6°C

3.3/–20.1°C

24.4/–78.2MW

Boiler input

Turbinegovernor

OK

0.0/–0.1MPa

3.0/–1.4°C

3.0/–0.7°C

5.5/–158.3MW

Boiler input/turbine

governor

Turbinegovernor

OK

0.0/–0.2MPa

6.9/–4.6°C

7.6/–4.7°C

24.4/–33.5MW

Boilerfollowcontrol

Turbinefollowcontrol

CoordinatedcontrolControl scheme


Fig. 8—SimulatorVerification UsingSite Commissioning.Actual plant processbehavior closelycorresponds to theplant behaviorpredicted bydeveloped simulator.

to be advantageous for controlling the main steampressure and temperature. Fig. 7 shows an example ofthe trial operation results. Just as the simulationanalysis predicted, the main steam pressure andtemperature control performance guaranteespecifications were satisfied.

In order to verify the suitability of the simulator,we compared data yielded by the simulator againstactual measured data. Fig. 8 shows some of the results.One can see that the simulator developed for thisWaigaoqiao project yields acceptably accurate resultseven with respect to dynamic behavior.

CONCLUSIONSThis article provided an overview of a new-

generation integrated monitoring and control systemthat Hitachi supplied to Shanghai Municipal ElectricPower Company’s Waigaoqiao Power Station inShanghai, China.

Present-day China is witnessing remarkable growthand demand for more information-intensive systemsand electric power, and we can anticipate increaseddemand from the mainland for the type of systemdescribed here. Hitachi is well positioned to providesuch systems based on reliability and experience tomeet this demand.

Although we successfully met the challenge ofmore rigorous control performance specificationsthrough the control technologies described here, wemust redouble our efforts if we are to keep ahead ofthe competition and develop products that satisfy even

ABOUT THE AUTHORS

Shigeharu TakahashiJoined Hitachi, Ltd. in 1978, and now works at the

Power Plant Control Systems EngineeringDepartment, the Information & Control Systems

Division, the Information & Telecommunication

Systems. He is currently engaged in engineering workon thermal power plant control systems.

Mr. Takahashi can be reached by e-mail at

[email protected].

Satoru ShimizuJoined Hitachi, Ltd. in 1994, and now works at thePower Plant Control Systems Engineering

Department, the Information & Control Systems

Division, the Information & TelecommunicationSystems. He is currently engaged in engineering work

on thermal power plant control systems. Mr. Shimizu

is a member of the Institute of Electrical Engineers ofJapan (IEEJ), and can be reached by e-mail at

[email protected].

Takaaki SekiaiJoined Hitachi, Ltd. in 2002, and now works at the

Coal Science Project, the Plant Analysis Group, thePower & Industrial Systems R&D Laboratory, the

Power Systems. He is currently engaged in R&D of

control systems for thermal power plants. Mr. Sekiaiis a member of The Society of Instrument and Control

Engineers (SICE), and can be reached by e-mail at

[email protected].

550

540

530555

545

53514

13

12

Flow

(kg

/s)

Flow

(kg

/s)

Pres

sure

(M

Pa)

Actual operation flows Simulator Steam temperatureSteam pressure

Air flow

Feedwater flow

Time (min)

Fuel flow

0 10 20 30 40 50 60 70

600

500

400500

400

30050

45

40

Tem

p. (

°C)

Tem

p. (

°C)

Tem

p. (

°C)


Calculated results

Calculated results

Calculated results


Main steam pressure

Time (min)0 10 20 30 40 50 60 70

more exacting control performance specifications inthe years ahead.

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hitachi_r2005_03_111