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Bindu Pillai, Dhara Trivedi, Vishal Mehta & Nilam Patel
from the boiler. The output shaft of the turbine is coupled to the alternator. A panel mounted tachometer is provided to
measure the turbine speed. A set of electrical bulbs and a water rheostat are used to utilize the electrical power produced by
the alternator. Exhaust steam from the turbine is let out to the atmosphere or to a condensor using the exhaust valves. A
separate centrifugal pump is provided to circulate the cooling water through the condensor. An evacuating pump is used to
remove the condensate from the condensor.
The setup is manually operated with a power generation capacity of 5kVA, alternator rotating at 3000 r.p.m
producing maximum of 3kW of which 1kW is used to illuminate the bulbs and rest is bypassed to the rheostat for heating
water in the tank. The used steam is passed through the condensor and converted to water. The fuel (diesel) consumption is
40 litres/hour and the boiler efficiency is 22%. Experimental set-up of mini thermal power plant is shown in figure 1.
Figure 1: Experimental Set-up of Mini Thermal Power Plant
POWER PLANT AUTOMATION
Automation of the mini thermal power plant was carried out in 3 phases:
Feasibility study of automating the plant and creating virtual simulation- The problems of the existing set-up was
identified and the scope of automating the plant was worked out. To support the idea of automation, first a virtual
simulation model was created.
Identifying the required sensors and actuators, its installation and testing- To address the problems with the
existing set-up different manually operated valves were replaced by motorized valves, sensors and actuators were
introduced at the required location. The installation was carried out and the entire set-up was automated. The
automated set-up was then tested for its performance in terms of efficiency, plant operation and monitoring.
Implementation of SCADA for the mini thermal power plant- Once the automated set-up was successfully tested
the next step was to establish remote access to the plant operation by implementing SCADA.
Problems with the Existing Set-up
The following problems were identified with the existing set-up:
No diesel pump to feed diesel into the diesel storage tank.
No indicator for water level and diesel level for water tank and diesel tank respectively.
All the valves of power plant setup are manually operated.
No accurate devices for the measurement of the process parameters.
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Automation and Virtual Simulation of Laboratory Based Mini Thermal Power Plant
Skilled man power required for operating the complete power plant.
No monitoring system available at power plant setup.
Scope of Automating the Plant
The existing plant was manually operated one and hence there was a need to replace the manually operated valves
with the motorized valves. To sense the liquid level, pressure and temperature, respective sensors had to be identified.
Some modification in pipelines was required and fianlly the whole system had to be integrated with PID controller.
Virtual Simulation of Mini Thermal Power Plant
The simulation of the entire automated setup of laboratory based mini thermal power plant was carried out in
LabVIEW-2010 by using DSC (Data logging and Supervisory Control) module. The Virtual simulation of lab based mini
thermal power plant is shown in figure 2. To start the plant put on the start (toggle) switch. If the tank is empty at initial
stage then the level sensor S2 will sense the signal and it will pass feedback signal to cRIO (PID Controller) which will
actuate Valve1 and allow water to feed into the water tank from water sump by Pump1. As level reaches up to 1000 mm,
S1will sense the signal and pass the feedback signal to cRIO (PID Controller)
and Pump1 immediately stops,
simultaneously Valve2 will be open. It remains fully open during the operation of the plant and Pump3 continuously
supplies water to the boiler.
Figure 2: Virtual Simulation of Mini Thermal Power Plant
In the same way if the oil tank is empty , level sensor S4 will sense the signal and it will give a feedback signal to
cRIO (PID Controller) which will actuate Valve3 and it will open. When the oil level reaches upto 700 mm, the level
sensor S3 will sense the signal and actuate Valve4 and it will be closed. When the level goes below 200mm, Valve3 will
open again. The initial steam temperature in the boiler is 29˚C. The bypass valve remains fully open until the steam
temperature reaches 135 ˚C (the maximum limit is 190 ˚C). At this temperature, the bypass valve will be closed and
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Bindu Pillai, Dhara Trivedi, Vishal Mehta & Nilam Patel
Valve5 will be open. Steam passes through the turbine, and in between there is a pressure transmitter and a temperature
sensor T1 mounted on the pipe line which will sense the pressure and temperature of the steam. As the steam temperature
crosses 170 ˚C the globe valve opens and the steam enters the turbine which in turn rotates the alternator connected to it. At
3000 rpm it generates 3kW power out of which 1kW is used to lit the 3 bulbs shown in the out-put panel. The used steam is
passed through the condensor and converted to water. Temperature sensor T2 and T3 sense the inlet and outlet water
temperature. The monitoring panel in the simulation reflects the status of the valves, pumps and sensors. Red color
indicates “OFF” and green indicates “ON” status in the simulation of any device at a particular time.
Benefits of Virtual Simulation
Virtual simulation is useful for understanding the real time working of power plant.
The simulation can be used as a virtual lab to give training to the students & professionals.
Installation and Testing
During the installation the manually operated valves of the existing set-up are replaced by the motorised valves.
Globe valve is located at the outlet pipe of the boiler. It is actuated only when the temperature of steam reaches 170˚C and
pressure of steam reaches 5bar. All other manually operated valves are replaced by automatic ball valves. Electric solenoid
actuator is used to actuate the valves. Level sensor is installed in the water tank and the diesel tank to sense the water level
& diesel level, total four thermocouples are used to sense temperature- temperature of steam at boiler outlet, inlet
temperature of turbine, inlet temperature of the condensor and outlet temperature of the condensor, one pressure transmitter
is used to sense the pressure of the steam at boiler outlet and all the sensors are integrated with the valves to provide signals
to actuate them. After the required modification in pipeline the whole system was integrated with PID controller as shown
in figure 3.
Figure 3: Automated Set-up of Laboratory Based Mini Thermal Power Plant
Benefits of Power Plant Automation
Indication of water level and diesel level in the tank can be acknowledged with the help of level sensor.
Automatic valves reduce operating time of plant.
PID controller controls the globe valve automatically as per the preset temperature and pressure.
Produced power is utilized for charging an I.C. Engine battery charger, to run pump for recirculation of water to
the condensor, to run fans of thermal engineering laboratory.
5. Automation and Virtual Simulation of Laboratory Based Mini Thermal Power Plant
Improvement in boiler efficiency by 6%.
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Automatic controller based operation improved the process monitoring and made plant operation easy.
Supervisory Control and Data Acquisition (SCADA) of Mini Thermal Power Plant
SCADA (supervisory control and data acquisition) generally refers to industrial control systems, computer
systems that monitors and controls industrial, laboratory, infrastructure or facility-based processes. A SCADA simulation
of a laboratory based mini thermal power plant was developed using LabVIEW-2010 data logging and supervisory control
(DSC) module which has a capacity to supervise the plant operation and perform data acquisition.
Features of SCADA Simulation
Supervisory Control of Mini Thermal Power Plant
The SCADA system of mini thermal power plant includes mini thermal power plant layout and indicators for onoff condition of various valves and sensors of plant.
Data Acquisition in Mini Thermal Power Plant
The main objective of data acquisition system is to acquire data from temperature sensor, pressure sensor and
level sensor of mini thermal power plant. Data acquisition tab is shown in figure 4. Operator can monitor data acquired
from various sensors like temperature sensor, pressure sensor and level sensor. Value of steam temperature and steam
pressure, at a particular time, can be monitored through this simulation along with High and Low position of the level
sensor.
Process Monitoring with PID Controller
Operator can monitor position of globe valve and motorized damper with help of PID controller and based on the
preset temperature and pressure values, control the % opening of the valve.
Historical Data
SCADA simulation features viewing of historical data in the form of plots. Operator can view data of various
process parameters such as tmeperature at globe valve, temperature at condensor inlet and outlet acquired.
Figure 4: SCADA Simulation
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CONCLUSIONS
Due to automation of the plant the boiler efficiency was improved from 22% to 28%. Fuel consumption was
reduced from 40litres/hour to 33litres/hour. Plant operation is more efficient due to automatic valves, sensors and PID
controller. Better utilisation of the output to charge I.C. Engine battery, lighting bulbs and fans of the laboratory and
driving the condensate pump. Power plant operation can be monitored through SCADA from a remote location.
ACKNOWLEDGEMENTS
The authors wish to thank Dr. Piyush Gohil, Professor & Head, Mechanical Engineering Department and Dr.
N.D. Shah, Principal-Faculty of Technology and Engineering (Chandubhai S. Patel Institute of Technology- Changa)
Charotar University of Science and Technology, Changa for their encouragement and support in undertaking the research
work. Special thanks to the Management for their financial and moral support.
REFERENCES
1.
Raju Gupta, S.N.Singh, S.K.Singal (Oct 07). Automation of Small Hydropower Station. International Conference
on Small Hydropower.
2.
Pollution Prevention and Abatement Handbook, (July 1998). Thermal Power: Guidelines for New Plants.
3.
G. Prasad, E. Swidenbank, B. W. Hogg (September 1999). A Novel Performance Monitoring Strategy for
Economical Thermal Power Plant Operation, IEEE Transactions on Energy Conversion, Vol. 14, No. 3,.
4.
British Electricity International, London (1991), Station Operation and Maintenance, Vol. G, Modern Power
Station Practice. pp. 45 1-622.
5.
Salisbury, J.K. (1961), Power Plant Performance Monitoring, Journal of Engineering for Power, Oct., pp 409422.
6.
K. Krishnaswamy, M. Ponnibala, “Power Plant Instrumentation”, pp.28-33,182-196. PHI Learning Private
limited.
7.
A. Ramirez-serrano, S.C.Zhu, S.K.H. CHAN, S.S.W. CHAN, M. Ficocelli,B.Benhabib (2002). A hybrid PC/PLC
architecture for manufacturing system control – theory and implementation. Journal of Intelligent Manufacturing.
8.
K. Gowri Shankar (2008). Control of Boiler Operation using PLC – SCADA, Proceedings of the International
Multi Conference of Engineers and Computer Scientists Vol. II, IMECS 2008.
9.
M. N. Lakhoua. (June 2010), SCADA applications in thermal power plants, International Journal of the Physical
Sciences Vol. 5(6).
10. M. Patel, G. R. Cole, T. L. Pryor, N. A. Wilmot (2004). Development of a novel SCADA system for laboratory
Testing. ISA - The Instrumentation, Systems, and Automation Society Transactions, pp 477–490.
11. A. Daneels, W.Salter (1999). What is SCADA? International Conference on Accelerator and Large
Experimental Physics Control Systems, Trieste, Italy.
12. Baily D, Wright E, Practical (may 2003). SCADA for Industry, Elsevier journal of process plants.
13. Carke G, Rynders D, Wright E (2003). Practical Modern SCADA Protocols, Elsevier journal of process plants.
7. 81
Automation and Virtual Simulation of Laboratory Based Mini Thermal Power Plant
14. Ken Barnes, Briam Johnson, Reva Nickelson (January 2004). Review of Supervisory Control and Data
Acquisition (SCADA) Systems, Idaho National Engineering and Environmental Laboratory Idaho Falls, Idaho
83415.
15. Mohamed N. LAKHOUA (Number 2009). Application of Functional Analysis on a SCADA System of a
Thermal Power Plant, Advances in Electrical and Computer Engineering Volume 9.
16. Jonathan W. Valvano, Bapi Ahmad, Jagadish Nayak (May 1999). Real Time Data Acquisition and Control,
ASEE Austin, TX.
17. Altech, steam turbine test rig, Instruction manual and Energy machine, installation and maintenance
for ECOTHERM (steam boiler).
18. www.ni.com/labview/labviewdsc.
19. www.dewetron.cz/pdf/1msw078_082a.
manual
