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LEARNING REPORT ON FOREIGN TRAINING

UNDER STG PACKAGE

OF NTPC-KUDGI

AT M/S TOSHIBA ,FUCHU FACTOR

JAPAN

ON

ENGINEERING ASPECTS OF DDCMIS

BY

Y.M.BASAVARAJU

AGM(C&I)I/C-ERECTION

NTPC-KUDGI

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Learning:- Even though concept and philosophy of all DDCMIS systems are similar, asfor as the implementation is concerned it changes. Instead of comparing with DDCMISof other NTPC plant, here we got the opportunity to understand the way they haveimplemented from the angle of operator and as well the engineering aspects. This willcertainly help in better quality erection and also to clear the concepts to new Engineersas well as to old experienced NTPC- operators. We also know the advantages andlimitations of this system with respect to existing NTPC system.Visit to plant and their best practice explained in detail which can be looked into, sincereduction of pollutants is the requirement of the day even to India due to highenvironmental awareness and movements. They are following one of the best practicefor pollution control of SOX, NOX, particulate. The final emission values are comparableto clean fuel like Gas/ liquid fuel.CHP (Coal handling plant) and AHP (Ash handling plant) is also model to us, no tracesof dust and was found very systematic, everything was found automated and totalpower plant was operated with minimum manpower i.e 0.17/MW. Some best practicescaptured are made part of the report. Here it may be noted that, this power plant isrunning since 1991.

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Following DDCMIS systems are supplied to 800MW units of Kudgi.1. SG controls; SPPA-T3000 by M/S Siemens (OEM) is supplied by M/S Doosan2.TG Controls; TOSMAP-DS TM/EV SR-22.01 is supplied by M/S Toshiba3. Station C&I controls; CENTUM VP is supplied by M/S Yokogawa India Limited.All the three control systems are provided by MNCs, TOSHMAP-DS TM/EV is the systemsupplied by M/S Toshiba for turbine and Auxiliaries control.Training was on engineering aspects of this system by their design Engineers who wereinvolved actively in engineering their standard system to meet the specific needs ofNTPC along with the Indian grid requirements.In the three week training they covered system architecture, software aspects,hardware components, communication networks used along with visit to turbine andgenerator manufacturing unit, DDCMIS manufacturing and testing unit, TSI classes byOEM M/S Shinkowa with demonstration of calibration and diagnostic features with amodel. They also took us to 4100MW coal based power plant having units 700x3 MW +1000x2 MW units at Hekinan - Nagowa .This training covered hardware supplied to DDCMIS along with its functional details.Kudgi specific DDCMIS architecture and explanations of various elements of DDCMIS.Panel general arrangement and visit to their manufacturing, assembly and testingfacility at Fuchu, Japan. Operator interface and HMI functionality and the mimics,control blocks, groups, logs, bar graphs, alarms provided for easy operation andrequired historian of critical data.Engineering station also explained in detail giving demonstration about logic, tag,display, I/O assignment ; modification in the system and explaining the procedure to befollowed for the same for on line as well as for off –line modifications.Critical controls related to EHC start-up and load / speed controls, associated high-pressure governing system, details about actuating stop and control valves of mainturbine, HP/LP bypass system were covered in detail along with BFP pressure controlwhich is unique concept of M/S Toshiba. One secession was devoted to other TG andAux controls.In the well organised plant visit, they have taken us to manufacturing units where, Lifts,railway engines, advanced GIS and solid-state switch gears manufacturing unit andTurbine and Generator manufacturing units were covered. We could experience theirsystem orientating, productivity, discipline, importance and emphasis given tocleanliness and team work.In addition to this we could also see Turbines and generators in various stages ofmanufacturing to get bird’s eye view and intricacies involved in the manufacturing ofmain equipment (TG) at different stages from receipt of raw material to final assemblyand testing.

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Unit architecture showing ACS components – highlighted.

The typical TOSHMAP-DS/EV is shown in the above over view with all itscomponents.This system can be catagarised into three groups.1. Automatic control system(ACS)2. Human machine interface(HMI)3. Integrated Engineering station(IES)Communication and interconnection is achieved through C-NET and I-NET. Whichare redundant and with a speed of 100Mbps.ACS is specifically designed to control the entire power plant. They use 32-bitmicroprocessor that provides high performance and large capacity. Up to 128control loops can be configured in a single controller and individually maintainedon-line, while other loops are operating. The compact PCI back plane used for theCPU bus provides open system connectivity to industrial standard.Two type of I/O configurations are used in this system, Toshiba proprietary I/O isused for special purposes like Speed impulse processing, or where large number ofinputs and outputs are required. Second one is device net interface which is anindustrial standard based on CAN. Here mainly temperature inputs are processedthrough Device net.

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HMI provide state- of -art process operation and monitoring for power plants. TheHMI station meets real time operational needs by the operator, monitoring andreports required by shift charge Engineers and top management for efficientoperation of the power plant. Third party interface like, through Pi sever tocorporate centre and remote service facility to OEM and also operation facility tooperate third party control systems like CPU in this case with in- built securityfeatures.There are three type of HMI stations, OWS, which provide tailor-made views foroperation, LVS operating stations, in addition to the above they provideannunciation in three groups to facilitate immediate action by the operator. SVShandles archival of data and it can also function as OWS.LVS gets plant data through C-NET and OWS through IES, hence providingredundancy, single element failure will not affect the HMI functionality.IES provides a comprehensive set of engineering and maintenance functions for HMIand ACS. This works on windo-7 platform, it contains all HMI and ACSfunctionalities; logic tool, TAG database tool, display tool, log and report tool,consistency check function, delivery functions and launcher.Brief functionality of each element is explained below:-Different elements of DDCMIS System:-•SVS: Server Station•OWS: Operator Work Station (RDS Client)•LVS: Large Video Screen OWS•RDS: Remote Data Server•ACS: Automatic Control System•IES: Integrated Engineering Station•LTD: Long Term Data storage server•RSS: Remote Service Station•C-LBP: Colour Laser Beam Printer•OPC: OLE for Process Control Server

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In this SVS serves has historian along with LTD. LVS and RDS stations store the latestapplication data and fetch and serve as HMI. Work stations depend on RDS for fetchingthe information and also for control.In addition to security features remote service station is also provided for gettingremote assistance from the OEM.SVS , OWS functions are given below.- Alarm List & Band- Schematic Display- Group Display- Group Operation- Trend Graph (Historical Data Storage & Retrieval is included)- X-Y Plots- Event List- Event Log- Data Summary- Display Hard Copy- Data Exchange with the Long data sever- Remote desktop service (RDS)IES Functions- Logic ToolTo configure control softwareTo monitor control value/statusTo update control parameterTo simulate control value/statusTo collect error logTo setup configurationTo configure Tag database- Graphic ToolTo configure Graphic DisplayTo define Graphic Symbol & Faceplate- Consistency CheckTo check database consistency- DeliveryTo distribute software to each station- System BuilderTo setup system configuration parameter

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These are standard features of any DDCMIS system, for monitoring, long-termstorage and fault and root cause analysis whatever data is required like, alarm,event, diagnostic alarms, shift log, daily log monthly log etc are provided along withself triggered pre and post trip logs. Alarm is having a resolution of 1sec. SOE is notprocessed in the TG DDCMIS, process and diagnostic events required at resolution of1ms are provided by the system in the digital form to station C&I system.

Group display, bar chart, trend graphs etc are configurable by operator , standarddisplays provided by engineering is already configured. Mimics for various P&IDand aux systems are configured in a user friendly way.

Some critical points observed in the Toshmap DDCMIS system is givenbelow:-

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M/S Toshiba general configuration is shown in the above diagram. C-Net is forcontrol network, I-Net is for information network. As can be seen from the controllerconfiguration given below, all other futures are standard to most of the DDCMISsystem. In this case device net is used for processing temperature signals. Fieldinputs are connected either through CTC(Connector terminal converter)or throughdevice net terminals.

A controller consists of CPU unit, PI/O unit, CTC, DeviceNet Module, and a network.A CPU unit contains two pairs of CPU systems which consist of a CPU board andsome communication boards to interface with other units. 8 of 19 slots are assignedper a CPU system. Slots 00 to 07 are for CPU-A, and slots 10 to17 are for CPU B. TheCPU board is mounted at the left-end of each slot group, i.e. CPU-A is slot 00 andCPU-B is slot 10. PI/O unit has 19 slots. Toshiba’s PI/O board and MIF board(Modbus data communication board: RS232Cinterface) can be mounted in this unit.

Communication between PI/O unit and CPU unit is performed byoptical cable. This interface of CPU unit is COM board, and PI/O unit side is IOBboard.The IOB board is mounted in slot 00 and 01 of each PI/O unit slot. Other PI/Oboards that are AI, AO, DI,DO etc. are mounted in slot 02 to 18.Field signals exceptfor DeviceNet are received by PI/O boards via marshalling terminals and CTC(ConnectorTerminal Converter). CTC is a terminal of field signal inputs. A fieldsignal of DeviceNet module is received by DeviceNet module via only marshallingterminals. DeviceNet modules are mounted in System cabinet. CTCs are mounted inTerminal cabinet. Each device is arranged in the DIN rail vertically. And it is locatedboth front side and rear side of System and Terminal cabinets. Between CTC and

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PI/O board are connected by flat cable. Between CNT and HMI are connected byEthernet cable.

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C-NET (Control Network)- Redundant Data Highway- 100Mbits/second Ethernet- Communication for Real-time Control & Monitoring Data- Download of Control Configuration Information from IES

I-NET (Information Network)- Redundant Data Highway- 100Mbits/second Ethernet- Down-load of HMI Configuration Information from IES

TG-NET (TG-DCS Integrated Network)- Redundant Data Highway- 100Mbits/second Ethernet- Interface with other unit & CPP unit- Interface with BOP DCS unit & Master Clock System- Interface with Remote Service Station

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Time synchronisation of the system with master clock is achieved with NTPInterface, IES,SVS and LTd are synchronised with master clock and they serve as thereference for other units /systems down the line in the DDCMIS.

TYPICAL SETUP ESTABLISHED AT FUCHU FACTORY JAPAN FOR TESTINGPURPOSE:-

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NETWORK PANEL WITH DIFFERENT ELEMENTS:-

PANEL OVER VIEW;-

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Controls related to sequential control and closed loop controls implemented in theDDCMIS were discussed. One of the major sequential control i.e. turbine start-up control (ATRS) isshown in the above screen. There is provision to start manually as well in auto mode. Un like othermanufacturers, steps are very few, start permissive and soaking at 400rpm and 700rpm is done atbefore going to the 3000rpm, synchronisation and block loading is accomplished in the last step.Once synchroniser is on, speed matching is done by EHC, voltage matching by AVR andsynchronisation command is executed by the synchroniser unit.

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Depending on start-up condition 1. Cold start-up 2. Warm start-up 3. Hot start-up , accelerationrates and socking times are selected. These curves decide the soaking time and acceleration from400rpm onwards. 1st stage metal temperature dependent start-up modes are indicated below.

Other sequential controls are simple; they were explained in detail during the training.

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EHC uses speed control, load control and initial pressure control (Initial pr. Control as backup toprevent wet steam entering the turbine). Speed control is used for start-up and for Governingcontrol, where its output is directly affected by grid speed/frequency changes, a 2 HZ raise infrequency totally unloads the unit.

Load control is possible manually, auto regulation mode with or without frequency influence. In theALR mode remote set point is accepted and is called follow-up UCS.

As shown in the above fig. In case of LL mode in action load is un affected by grid frequency changes.

Where as in case of governor mode it is affected at 4% droop.

The way it is achieved is shown in the following block diagram with the curves showing trackingpattern on changes in grid frequency.

In addition to these basic controls, slave controller called valve position controller is provided forpositioning the control valves. This controller based on the control valve characteristics convertssteam flow demand into valve position (% of open/close) demand. For this purpose it gets thefeedback of valve position. Since it is operated hydraulically, response is fast.

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This shows how bias is applied to governor mode, since it is maintained always higher than LLdemand, LL remains in service and un affected by grid frequency up to 10%/bias set.

Here Gov mode is in service since it goes through minimum gate, and LL followsgovernor till it reaches generator upper load limit.

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To meet grid requirement specific to India, RGMO features are added where infrequency dead band where there should not be any change in MW w.r.t frequencychange, beyond which response at the required rate is introduced to meet grid coderequirement.As can be seen from the above curve load change at the higher site is clamped to 5%for sudden fall in grid frequency.

Control loops in TG system:1. CONDR HW NORMAL & EMERGENCY LVL CNTL.2. DEA & FW TK LVL CN3. COND WTR MIN FLOW CNTL.4. DEAERATOR & FW TANK SPILL OVR LVL CNTL.5. CEP-A/B/C RECIRC CNTL.6. CONDR SPILL LVL CNTL.7. DRIP PMP MIN FLW CNTL.8. HP FW HTR NO.8A,8b,7A,7B,6A & 6B NORMAL & EMERGENCY LVL CNTL.9. LP FW HTR NO. 4, 2 & 1 NORMAL & EMERGENCY LVL CNTL.10. LP HTR DRN TK NORMAL & EMERGENCY LVL CNTL.11. DEA & FW TK INL CRH PRESS CNTL.12. DEA & FW TK INL AUX STM PRESS CNTL.13. HP FLASH BOX TEMP CNTL.14. CW DP CNTL.15. BFPT A/B LUBE OIL TEMP CNTL.16. BFPT HDR INL CRH PRESS CNTL.

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17. BFPT HDR INL AUX STM PRESS CNTL.18. LUBE OIL TEMP CNTL.19. GLND STM PRESS CNTL (FEED SIDE & UNLOADING SIDE).20. H2 GAS TEMP CNTL.21. EHC OIL TEMP CNTL.22. SCW TEMP CNTL.23. SCW PRESS CNTL.24. LPT BYP A/B CNTL.25. LPT BYP A/B SPRY CNTL.

Except DEA level control where 3 element controls is used, all other controls aresimple single element, traditional type of control loops.

Above fig shows the schematic of feed water control system.

It has following modes of operatio:-

1.Startup:-a. One BFP:-Differential pressure control mode(Called DP mode)

b. Feed water flow control mode(FW FCV) where boiler required pressure is less thanoperating pressure of BFP, FW station reduces the pressure and controls therequired flow.

2.M/T BFP changeover mode:-

a. MDBFP and TDBFP: Feed water flow control mode

b. M/T BFP changeover will operate while flow demand for both BFPincrease/decrease

3. Normal operation and S/D

a. Both BFP on flow water control mode.

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Functional testing of safety device and control and stop valves of Mainturbine.

Instead of ATT, EHC test function screen is provided, since high pressure governingusing servo valves(Moog) is used for regulating stop and control valves, Stop and control valves testis very simple. No mechanical safety devices are provided, over speed, axial shift and vacuum tripsare from electrical signal. Over speed is provided from control channel as well as from theprotection channel, having three separate speed pickups in each channel. These two channels arealso checked in the functional test for healthiness.

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Typical trip logic implementation in turbine:-

Three SSLW cards are used for implementing turbine trip in 2/3 logic. As it can be seen from theabove diagram sensor to relay element 2/3 redundancy is provided for higher reliability. i.e systemhas very high fault tolerance . Single sensor, cable, and card, relay failure will not result in spurious

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trip. and single element failure gives alarm to correct the same meanwhile.

As shown in the above diagram, thermal stress for HP/IP rotor and HP/IP casing are calculated basedon the 100% and 50% temperature. They are used for indication of LCFI( Life consumption) andstress in Kg/Cm2 in bar graph form for all the four channels .

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Turbo Supervisory Instruments:-

OVERVIEW OF VMS ARCHITECTURE;-

VMS SIGNAL PROCESSING AND ANALYSIS;-

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Above diagram depicts architecture, signal processing and Kudgi, integration ofvarious aux -VMS systems to single centralised station, in a single line diagram.

TSI for main turbine and also for BFPs both TD and MD, BFPs is supplied byShinkowa,Japan. One day training was organised at M/S Shinkowa on TSI. Key highlights of the secession is that they explained the concepts with live demonstration ofmodels for calibration and also for diagnosis.

Basically they are using non contact type pickups at an angle of 45deg to vertical asper standard. For measuring relative shaft vibration. Acceleration pickup mountedon the casing provides casing vibration and calculated absolute shaft vibration. Thisis the standard practice followed in the existing power plants of NTPC also.

Key phaser pickup signal is also used , non contact pickups by shinkowa are providedfor axial shift, differential expansions of HP,IP,LP for speed measurement twodedicated channels with 3 pickup each are provided for control and protection.

Diagnostic station receives all the signals from VMS stations i.e TG and station C&IVMS systems, 1x.1/2x,2x etc analysis -1x analysis, machine balancing to reducevibration etc can done through this station for all the connected equipments.

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Memorable Day with Hekinan CHUBU Electric power:-

By: Y.M.Basavaraju, AGM(C&I)I/C Kudgi

Hekinan Power Plant:

Hekinan Power Plant is the largest thermal power plant of Japan. It was built in the year1991 and

belongs to Chubu Electric Power Co. Some of the salient features of the power plantare: Capacity of 4100 MW with three units of 700 MW each and two units of 1000 MW each.

Area of 2 million sq m with 25% for main plant, 25% for ash disposal, 25% for coalHandling plant and balance 25% for green area.

Boiler uses bituminous and semi-bituminous coal and is once through reheat type.

Auxilary plant consumption is 5-6% and PLF is around 83-84%.

Transmission network of rating 275kV with voltage levels as 6.9kV (for HT) and 460V(forLT).

Cooling system is direct. Inlet from sea water (deep) and outlet to sea water (surface).

Thermal efficiency is around 42%.

Toshibal Turbine-Generator is supplied in one 700MW unit and two 1000MW unit.

It has 261 employees and 433 contract workers.

Overhauling of units is once per two years with a duration of around 100-120 days.

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The Hekinan Thermal Power Station, overlooking Kinuura Bay in Aichi prefecture, produces atotal of 4,100 megawatts and comprises five units. The first three each producing 700MW werebuilt in 1991, 1992 and 1993,while the last two, which produce 1,000MW each, were built in 2001and 2002.Thermal efficiency of power plant for latest unit #4 and #5 is 42.17%(HHV) and43.15%(LHV). Turbo generator is supplied by M/S Toshiba and Boiler by M/S IHI. Steam pr andtemperatures are 24.1MPa and 566/593 C respectively.

The plant's station and coal yard occupy an area of 1.6 million square metres, and thelatter is regularly sprinkled with water and surrounded by an 18metrehigh wind fence to reducedust, it is so designed the wind speed gets neutralised by the curvature design shown in theattached photo taken during the visit. Australia is the main supplier of coal, providing 57.6 percent, while Indonesia provides 27.1 per cent. It is unloaded from ships and sent to the station oncovered conveyor belts.

The plant also owns another 480,000sqm of reclaimed land, which is used for ash disposal.Each year 1 million tonnes of coal ash is produced by the plant, which is either sold or recycledwith more than 80 per cent of it going into making cement. The rest is buried on the plant's site.In addition, the plant has also nurtured a green area covering about 25 per cent of its total space.

The plant has placed great importance in minimising pollution and therefore includesa wastewater treatment system; a flue gas denitrification facility to treat exhaust gas withammonia (efficiency 80.90 per cent); a flue gas desulphurisation facility to treat sulphur oxideswith limestone liquid (efficiency 96.597per cent); and an electrostatic precipitator to reduce dust.

In addition to being a state of art facility, the power plant also won thetrust of the community. Chubu Electric Power, signed a contract with the government, Hekinancity and three other regional cities pledging to maintain environmental safeguards. While cityofficials closely monitor the power plant's activities, the plant itself keeps city authorities postedon a monthly basis and lets people access information and test results upon request.

They own six ships for importing the coal, each ship can carry 90,000 ton , unloadingtakes 3 days and to and fro trip takes about 2 weeks. 90% of the coal comes from Astralia andIndonasia, rest on spot purchase from various countries.

Componey is also actively involved in community development, under Electricity,GreenThinking,and the Environment initiative they have developed Electricity Museum,Healinggarden,Eco Park open to public. They have also developed fishing area around the plant and isvery populer among the neighboring residents.

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Japan, specifically local governments have stringent environment norms; to meet the same theyhave employed state of art pollution control measures which are new to our country, here it may benoted that we have particulate (Statute) limit of 50ppm and no limit specified for NOX and SOX. Briefcase study of the same is given below.Local government has prescribed following stringent limits for coal based power plant this can becompared with the emissions by clean liquid and gas fuel based power generation:-

NOX < 15 ppmSOX< 25 ppmParticulate level < 5mg mN3

NOx control measures at hekinan are extensive. Low-NOx burners are used in conjunction with theuse of over fire air to reduce the thermal NOx formed in the boiler. Further by selective catalyticreduction(SCR) of the NOx about 90% NOx produced in the boiler is removed. For this purpose theyare using KAWASAKI NOX removal system which uses ammonia for this purpose as shown below.

Desulphurisation of the flue gas is based on a wet limestone- gypsum scrubbing process. Thisrecovers good quality gypsum of a high purity. This system has an efficiency of 96.6%.

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Particulates are removed from the flue gas using two-stage process. Prior to the desulphurisationfacilities there is a high- performance dry-type ESP system. After the de SOX facility is another ESPfacility, in this case it is a wet-type facility, which reduces the total emission of particulates to 5ppm.

Single line diagram showing various flue gas treatments to remove NOX, particulate, SOX and againfinal stage particulate removal is shown above.

The coal storage yard is surrounded by wind fences of 20mtr high, which reduces the effect of wind.Water is sprinkled in the coal storage yard when necessary. Coal unloading equipment is providedwith dust covers.

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Coal storage yard with 20mtr fence to break the wind speed along with greenbelt around the yard.

Coal stack yard over view

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Coal yard with water spray and coal stacking, one month stock available in the yard

Ship unloading the coal, crushed coal is imported and is directly sent to bunkers

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Ship used for coal transportation.

Over view of power plant with its green surrounding.

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Ash dyke in service since 1991, only 20% ash dumped in to the pond which is not useable,80% is utilised for commercial purpose. This has impermeable membrane at the bottom andside submerged steel wall to prevent leaching of heavy metals to surrounding water bodyand to ground water.

In line with the concept of continual improvement they have incorporated bio-fuel mix with the coal, woodchips/ waste wood and sludge treatment by Municipal corporationsderived fuel (carbon derived from sludge) is mixed with coal before coal bunker, about 1 to 2% ofbio-Fuel can be mixed this way. They are able to burn waste wood to the extent of 400,000tons/year, in addition to the carbon derived from the sludge; waste wood from paper mills isimported. This helps in integrating with waste management of municipality/society around the plantin an economical and environment friendly way. Company is also able meet obligations againstrenewable energy quota to that extent.

Conclusion:- Over all it is very enlightening experience, more than 20 year old plant looks like abrand new plant without any trace of coal leakage and dust all over the plant, working at very highefficiency 43.15(LHV) , integrated with society and has become part of the society.

“The four community representatives from Krabi( Members of Krabi community)said they felt relieved to see that a coal fired power plant in Japan could function normallywithout polluting the environment or damaging local fishing or agriculture. They saidEgat( Electric generating authority of Thailand) needed to adopt transparent bestpractices if it intended to win public trust for the new coal fired plants it has planned”

This is very much applicable to India, specifically to green field projects like Kudgi, publicawareness on environment is picking up in India also, we need to adopt world class pollutioncontrol technologies. Integration with the society need to be benchmarked with Japan HekinanPower plant.

References:- Booklet and information by Hekinan power plant, KAWASAKI presentation on SOX and NOXremoval system, internet resources on power plant.

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