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Chapter 1
INTRODUCTION
This chapter provides an introduction about the SCADA based system, the
significance of the SCADA implementation and different potential of the design,
application in real time, an overview of design components which are used in design, and
configuration, control and managing the SCADA system to improve the efficiency and
reducing the cost of the design.
1.1.
What is SCADA?
SCADA is used for monitoring and controlling of the industrial processes. SCADA
stands for supervisory control and data acquisition. The processes which can control
using SCADA can be industrial, Infrastructural or Public Utilities. SCADA is used
around the world to control all kind of industrial processes [1].
Industrial processes include manufacturing, Production, Developments, and
Fabrication. Infrastructural processes include gas and oil distribution, Electrical power
and water distribution. Public utilities include light rail, airport, bus transit systems,
Shopping malls [1]
SCADA application has two major components.
1. The system or process you want to control/monitor. It can be electrical power
distribution, manufacturing plant, power plant or production plant.
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2. A group of the intelligent devices which control the system or process. These
devices include sensors and control input/output to monitor and control the system or
processes.
1.2.
Overview of the Design
The objective of this project is to implement the SCADA based thermal power plant
which uses minimal of hardware/software interfaces and provide the higher efficiency. It
also provides low cost solution and reducing the number of loses during process flow.
This project focused on generating the electricity using the water, boiler and steam
turbine. SCADA implementation helps to provide higher efficiency as well as monitoring
and controlling of the process parameters like generated power, turbine speed and quality
of the generated power. SCADA implementation provides the higher controllability due
to sensors, valves and meters incorporated within the path of the process flow. The same
project can be also applicable for various other processing flows like water purification,
Oil purification and manufacturing of the products. The goal of the project is to minimize
the unnecessary steps involve during any process flow and provide the higher efficiency
and throughput.
None of the power plant provides 100 percent efficiency due to various loses
incorporated during the process cycle. Losses can be due to physical damage of the
hardware like scratches, splitting or tearing of the components. Hardware components
tearing are also possible due to the high pressure of water and steam. Most of the
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components need to be replaced after some amount of time or they need maintenance.
1.3
Design Solution
This project provides the various solutions to minimize loses and provide the energy
efficient power plant which cost less and provide the higher efficiency. Here are some of
the techniques.
1. Removing the excessive particles using filters:
Instead of getting water directly from the reservoir it is fed into the tank and keeps
there for a while so heavy particles can be settled down at the bottom of the tank.
Now water is passed through some large filters following by tiny filter holes and
accumulated at the second tank.
2. Removing gases using Electro dialysis techniques:
Electro dialysis is used to filter out the dissolved particles and gases. This step is
essentially required for the removal of dissolved Oxygen. Dissolved oxygen in
boiler can origin serious deterioration damage in steam systems by attaching to
the walls of metal piping and other metallic tools and forming oxides (rust). It
also combines with any dissolved carbon dioxide to form carbonic acid that leads
further corrosion.
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Chapter 2
SCADA SYSTEM
This chapter describes basic applications and uses of SCADA system. This also
covers basic design aspects of the SCADA system. It clearly explains how to select the
particular SCADA system for specific requirements. It also gives details on the
monitoring and control of the Real time systems
2.1
SCADA as a System
SCADA is one kind of application which collects data from the factory through
various sensors and sends this information to the computer system or remote locations.
SCADA is control and management solutions for the most of the industries. SCADA is a
central control system which consists of controllers, Network interfaces, Input/Output,
communication equipments and software. All together SCADA system collects important
information and sends it to the computer or remote locations.
The most important part of the SCADA is remote terminal unit which is also
known as RTU. RTU consist of programmable logic converter which can be set to
specific requirements or it can also allow human intervention during the operation. For
example, in thermal power plan the water flow can be set to specific value or it can be
change according to the requirements. RTU also displays the error or any critical
warnings at control station so user may be aware of the developments. SCADA system
takes the reading of the meters and checks the status of the sensors in a regular interval so
that it requires minimal interference of human. SCADA system made of many data points
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which include monitor points or software/hardware points. SCADA system creates the
log of the all necessary events and save the history for future references.
2.2
SCADA Applications
SCADA is used for all kind of complex system where human interaction is
impractical. SCADA is used in the applications where there are more control factors
difficult to mange with the short time frame [2].
1. Power generation, transmission and distribution
Power stations use SCADA system to monitor the current flow, voltage level,
checking the status of the transmission line and circuit breakers. Also, sometimes it is
used to power off or shutdown particular sections [2].
2. Water distribution and Reservoir system
SCADA is used for municipal water distribution system to monitor the flow of the
water during the distribution. Also, reservoir water level and pressure can be measure
using the SCADA system [2].
3. Public buildings
Electrical heating, cooling system, lighting can be control using the SCADA to
provide automation and power saving during the normal usage of the buildings [2].
4. Transit Systems
SCADA is used for the traffic light signals, detecting out of order status of the
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signals, regulating the power in subways, bus stations and airports.
5. Generators and Turbines
Monitor and control the temperature and flow in heat exchanger unit and heat
recovery unit.
2.3
Human Machine Interface (HMI)
SCADA system uses interface which is known as human machine interface
(HMI). HMI is the place where the information is displayed and monitored to process by
human. The interface provides the controls so human can interface with the system. HMI
provides the access of multiple control units which can be PLC’s (programmable logic
unit) or RTU’s. Usually RTU and PLC is pre program according to the requirements but
monitoring of them is difficult for the users. SCADA system communicates with the
PLC’s throughout the system and provides the information to the user using network
interfaces.
The HMI provides the graphical presentation of the system. For example, it
provides the graphics picture of the pump connected to the tank. User can see the flow of
the water and pressure of the water. Also, User can on/off the supply of the water within
the particular pipes. HMI also provides the multiple displays so user can control more
equipment at a time. The important part of the HMI is an alarm system which is activated
according to the predefined values. For example, the tank water level alarm is set to 80%
and 90% values. If the water level reaches above the 80% the alarm gives normal
warning and if water level reaches 90% the alarm gives critical warnings. According to
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the warning user can control the flow of the water from reservoir to the tank.
SCADA system also uses database to keep record of all the measurements and
particular state of the controllers. Also, it provides the information for troubleshooting of
the system, schematic diagram of particular parts or sensors, detailed graph of the usage
of the particular segments, installation and maintenance of the system
2.4
SCADA Animation

Standard Animation
SCADA animation consists of different color bars, text, rotating/sliding parts,
level indicator and position of the parts using different colors. Basic animation of
the SCADA system is shown below.
Figure 1 Standard SCADA Animation [3]

Modern Animation
Some company provides the software which can give the high graphics 3D view
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of the particular parts as well as sharp images.
Figure 2 Old Fashion Vs Modern Animation [3]
2.5
SCADA System Benefits

Control units have wide range of temperature and ability to operate in rough
situation.

SCADA system provides on board mathematical and graphical information.

SACDA system has ability to measure and store the historical information.

SCADA system is easily expandable. We can add new set of control unit and
sensors according to the requirements.
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Chapter 3
WORKING OF SCADA SYSTEM
The SCADA system mainly performs the following functions [2].
3.1
Data Acquisitions
3.2
Data Communication
3.3
Information/Data Presentation
3.4
Monitoring/Control
These functions are performed by sensors, RTU’s, Master Units and
Communication networks. Sensors are used to collect the important information and
RTU’s uses this information to display the status of the system at the control equipments.
According to the status of the system user can give command to the other system
components. The operations send the important command through the communication
network [2].
3.1
Data Acquisitions
The Real time system consists of thousand of components and sensors. It is very
important to measure the status of the particular components. For example, some sensors
measure the water flow from the reservoir to the tank which is input to the system. Some
sensors measure the valve pressure as the water is release from the reservoir [2].
Some sensors indicate the normal event of the system. For example, in production
environment sensor counts the number of produced product or the number of defected
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products. Some sensors indicate the condition (on/off) of the particular system
components. Furthermore, some sensors provide very critical information which should
give the accurate results. For instance, it is important to measure the temperature of the
system as it can damage the system. Temperature values are predefined in the system so
that it sounds alarm when system reaches above the threshold value.
3.2
Data Communication
Simple electronic control system uses wired network to communicate between
user and devices but in Real time application there are lots of sensors and components
which should be control remotely. It is important to have strong network between all the
components and user. Early, SCADA network used to communicate through radio and
modem [2]. Today, SCADA uses internet as a communication medium. All information
is transmitted through internet using specific protocols. Sensors and relays are not able to
communicate with the network interface so RTU (Remote Telemetry Unit) is needed to
establish the communication between sensors and network interface [2].
The RTU converts the input from the sensors into specific protocol and send it to
the masters. According to the masters feedback RTU received the protocol formatted
command and apply the electrical signal to the relays [2].
3.3
Information/Data Presentation
Normal circuit network have some indicator which can be visible to the operator
but in Real time SCADA system there are thousands of sensors and alarm which are
nearly impossible to handle simultaneously. SCADA system uses Human system
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interface to provide the all information gathered from the various sensors. SCADA
master works as a human interface. It has many different functions. Master collect the
information from the different sensor also process the accumulated information and
provide the necessary suggestion to improve the efficiency as well as indication of the
alarms [2].
3.4
Monitoring/Control
SCADA system provides the different switches and displays at the control center.
Any part of the process can be turned on/off from the control station using these switches.
For example, if the part following the water distribution system broke up or
malfunctioning then water control can be stopped or slowing down directly from the
control station. Mostly, SCADA system is implemented to work automatically without
human intervention but it is also possible to override the automatic control from the
control station [2].
Most of the monitoring and control operations are performed by RTU’s or PLC’s.
As we can see from the figure that SCADA system RTU Reads the flow level and flow
control form the sensors and sends the set points to the PLC’s. PLC1 compared the flow
with the set point and according to that it manages the speed pump. PLC2 observes the
flow and compare it with the set points and according to that it manages the flow.
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Figure 3 Schematic Diagram of SCADA System [1]
Figure 4 Circuit Diagram of Comparator
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3.5
SCADA Communication Protocol
SCADA system uses protocol for communicating between different RTU’s. IEC
(international electrotechnical commission, DNP3 (Distributed network protocol version
3) and modbus are most commonly used protocols [5].
IEC and DNP3 provide more functions and used to handle large amount of data.
Because of the more functionality and ability to handle large amount of data DNP3 is
mostly used around the world [5].
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Chapter 4
SCADA SYSTEM OF A THERMAL POWER PLANT
4.1
Functionality of SCADA Based Thermal Power Plant
Thermal power plant uses steam as a primary requirement to move the wings of
the turbine. After the passing through the turbine this steam is condense in a condenser.
Steam is generated by different type of fuel depends on the availability and requirements.
Different types of thermal power plant are classified according to the type of fuel and the
primary mover in the plant. The functionality of the thermal power plant can be
understood by the following diagram [12].
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Figure 5 Functionality of Thermal Power Plant [12]
The overall efficiency of the power plant can be measured by the ratio of the
temperature of the steam input and output. Higher efficiency requires the higher pressure
and higher temperature. The over heated steam is rotates the wings of the turbine and
then return back to the MP body and BP body of the turbine [12]
Most of the thermal power plants can automatically operate but it still allows the
access to human intervention to take some critical decision. Most of the power plant have
alert and monitor system which can be easily operated from the control room.
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4.2
Architecture of SCADA Based Thermal Power Plant
The architecture of the SCADA based thermal power plant is shown in the
following figure. The power plant is connected using the network Ethernet. The network
Ethernet allows the file transfer between the different stations. Also, it avoids the burden
of the node bus network [12]. There are three levels in SCADA system: acquisition,
processing and monitoring. The SCADA system is made of different components which
transfer information using the interface [12].
Figure 6 Architecture of SCADA System [12]
I/A: Intelligent / Automation
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FBM: Field bus modules
FCM: Field bus Communication module
AW: Application work station
WP: work station processor
CP60: control process60
DNBT: Dual Node bus 10 Base –T Interface
4.3
Application of SADT Method
The SADT model can be based on the type of the SCADA system. To model the
system we need to first determine the overall function of the system, divide the system
into different sub systems. The SADT model can be made of different stages for example,
in Thermal power plant the main module is used to check the overall function of the
power plant. This module is then divided into the sub modules. Each sub module has its
own functions [12]. The following figure shows the top down hierarchical methodology
of SADT model [12].
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Figure 7 Hierarchical Methodology of SADT Model [12]
SADT Model can be implemented by actigrams. The most top module is
generally used to monitor the signal of the power plant. Now this top module is divided
into sub modules. This process continues to the last decomposition level. The following
figures show the different level of SADT.
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Figure 8 A0 Level of SADT Model [12]
Figure 9 A1 Level of SADT Model [12]
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Figure 10 A2 Level of SADT Model [12]
Figure 11 A3 Level of SADT Model [12]
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Chapter 5
THERMAL POWER PLANT
5.1
Introduction
The coal used in the barbeque is also used to generate the steam and through this
steam it can generate the electricity. As the population increases the requirement of the
power also increases. Nuclear power plant is also a solution to this demand but it is not
safe as thermal power plant. Thermal power plant uses water as a primary resource and
water is heated to generate steam. This steam is used to spin the turbine and generate the
electricity. The steam which passed through the turbine is condensed using condenser [7].
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Figure 12 General Layout of Thermal Power Plant [8]
5.2
Components of a Thermal Power Plant
1. cooling tower
2. cooling water pump
3. 3 phase transmission line
4. 3 phase unit transformer
5. Electric Generator
6. low pressure turbine
7. condensate extraction pump
8. condenser
9. intermediate turbine
10. steam governor valve
11. high pressure turbine
12. deaerator
13. feed heater
14. coal conveyor
15. coal hopper
16. pulverized fuel mil
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17. boiler drum
18. ash hopper
19. super heater
20. forced draught fan
21. reheater
22. air intake
23. economizer
24. air preheater
25. precipitator
26. induced draught fan
27. chimney stack
5.3
Coal Fired Thermal Power Plant
More than half of the energy is generated using the coal based thermal power
plant. The basic concept is to produce the electricity from the energy stored in the coal.
The energy stored within the coal is used to generate the electricity and this electricity is
used in industrial, commercial and residential.
How coal fired thermal plant produce electricity?
First the energy conversion takes place in the boiler. The coal is burnt to generate
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the heat. Carbon in the coal combines with the oxygen and produces the carbon
dioxide.
Next, the thermodynamic process takes place. The heat from the fired coal boils
the water in the boiler and produces the steam. This steam is transferred to the turbines.
This high pressured steam collides with the wings of the turbine at high speed. This will
cause the pressure on the turbine wings and rotates the turbine. This steam is then
condensed and sends back to the boiler and repeats the same process again.
In final stage, rotation of the turbine rotates the generator rotor based on the
principal of electromagnetic induction. These stages also incorporate many different sub
stages and technologies. For example, combustion, heat transfer, thermodynamics,
aerodynamics.
Let’s consider we have a power plant of capacity 500 MW.

2 million tons of coal will be required to produce the power

Approximately 1.6 million meter of air per hour is delivered by air fans.

The total ash produced from this combustion is 200,000 tons annually

Gases like carbon dioxide, sulphur dioxide and nitrogen oxide can damage the
atmosphere.

To condense all the steam it will require 50000 cubic meter per hour of cooling
water
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
Electrical generator produce very large amount of current and heat which can
be condensed by water and hydrogen.

The boiler produced around 1600 tons per hour of steam at temperature of 550 to
600 degrees.

The water is returned back to the source with only increase of 3 or 4 degree
centigrade

The cooling plant requires 400 cubic meters per day for fresh water to compensate
the losses during the whole cycle.
5.4
Basic Layout of a Thermal Power Plant
Thermal power plants are mostly used to generate the electricity. Thermal power
plant releases large amount of green house gases in our atmosphere. The general layout
of the thermal power plant includes the following main components.

Coal and Ash circuit
Coal and ash circuit is used to supplying the coal to the boiler and collecting the
ash that is produced after burning of the coal. This includes the components used
to transfer and storage of the coal and ash.

Air and Gas Circuit
Air is the most important factor for combustion of the coal. Hence, it is required
to supply the sufficient amount of air for the combustion of the coal. The
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exhausted gases used to heat the air before releasing to the environment.

Feed water and steam circuit
These components are used to supply the generated steam to the turbine and also
for cooling the steam which is passed through the turbine. This steam is
condensed to form the water. This water is used again for the same process.

Cooling water circuit
This part is used to condense the steam using water. It requires large amount of
water for cooling the heated steam. The water is generally taken from the river or
reservoir.
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Figure 13 Basic Layout of Thermal Power Plant [9]
5.5
Working of Thermal Power Plant
Thermal power plant uses coal or natural gases to generate the heat which is used
to boil the water. This boiled water generates the steam, which feeds to the turbines. The
turbine is connected to the generator. This generator provides the electricity to the
consumers.
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The following are the steps for the process of generating electricity
1. Water Intake
The water is feed to the boiler for generating the steam. The water is driven from
the river, pond or reservoir. If the water is not pure then it is filtered using various
techniques. Also, this water can be used again and again for the next cycle.
2. Boiler heating
The boiler is heated using the coal or natural gases. The high temperature causes
the water to transform in to the steam. This steam is feed to the next stage for the
generation of electricity.
3. Steam turbine
The steam generated using boiler is feed to the steam turbine. The pressure of the
steam applied on the blades of the turbine. Hence, the wings of the turbine rotate
according to the pressure of the steam.
4. Generator
The generator is normally connected with the turbine and it produces the
electricity. This produced electricity is passed to the consumers using other
circuits.
5. Special mountings
There are some other components like economizer and air pre heater. Economizer
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uses the heat from the exhausted gases to heat the feed water. An air pre heater
heats the air sent to the combustion to improve the efficiency.
6. Ash Collection Unit
There are many waste material produced during the whole cycle so it is required
to collect all these waste materials and prevent them to go into environment.
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Chapter 6
THERMAL POWER PLANT COMPONENTS
6.1
Steam Generator
The steam generator produce the high quality steam required for the steam
turbine. Steam generator is a one type of large heat exchanger used to thermally connect
the reactor plant and steam plant. A steam generator also contains other components like
economizer, steam drum, furnace and super heater coils. Some times safety valves are
also required to avoid unnecessary boiler stress.
6.1.1
Boiler Furnace and Steam Drum
The water enters into boiler through economizer and from there it passes to the
steam drum. The boiler transfers the energy to the water by using the coal as a fuel. As
the water comes into the boiler it is converted into steam using the heated water walls.
The Generated steam enters into the steam drum and passes through the number of steam
and water separators. This separators and dryers are used to remove the water from the
steam. This whole process is called natural circulation [7].
6.1.2
Super Heater
Some power plant uses super heater which is used to heat the steam beyond the
saturation temperature. After passing the drying equipment inside the drum the steam is
feed to the furnace called super heater. Super heater uses the hot flue gases to provide the
more energy to the steam vapor. This super heated steam is now above the saturation
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temperature and is passed to the turbine [7].
6.1.3
Reheater
Many power plants contain the reheater which is used to provide the more energy
to the steam so it can drive the blades of the turbine. The reheater uses flue gases outside
of the tubes to produce highly energized steam [7].
6.1.4
Fuel Preparation System
Thermal power plant uses natural gas, fuel oil or coal as the fuel. Coal from the
storage is crushed into small particles. This coal is conveyed through the belt and feed to
the coal feed hoppers. Some power station uses fuel to generate the steam. The oil is
stored into the storage tanks and must kept warm to prevent congealing and becoming
unpumpable [7].
6.1.5
Air Path
The combustion unit requires sufficient air for burning of the coal. The draft takes
the air from the atmosphere, warm the air in preheater and feeds the air in furnace wall
using the air nozzles [7].
6.1.6
Ash Collector
The flying ash collected by the electrostatic precipitators or filters. The flying ash
is collected by filters and then transported using the vehicles. They flying ash should be
periodically removed from the hoppers. The bottom ash is collected using the hopper.
This hopper is filled with the water which quenches the ash.
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6.2
Steam Turbine
The steam turbine is the rotating machine which has large and heavy shaft. This
shaft requires supports and need to keep in accurate position. The shaft contains number
of bearings to minimize the friction during the rotation. It also uses lubricant to further
reduce the friction.
6.2.1
Bearing Gear
Bearing gear is used to supply the rotation to the shaft at low speed even after the
unit it stopped. When the unit stops completely then there is a chance for the shaft to
bend if it is remained in one position too long. The reason behind this is the heat inside
the turbine is concentrated at upper portion of the case. This could lead to bending of the
shaft.
6.2.2
Condenser
Figure 14 Water Cooled Surface Condenser [7]
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Condenser is used to convert the steam into water. Condenser is made of tubes
and water flows through the tubes. The steam from the turbines passed over the
condenser tubes. The condensers are also known as heat exchanger. To achieve the
higher efficiency the condenser temperature is kept as low as practical. Air cooled
condensers are used where the supply of water is not enough. The condenser uses same
water again and again from the tank or it can also use one time water directly from river
or lake.
6.2.3
Feed Water Heater
Figure 15 Feed Water Heater [7]
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Feed water heater is used to heat the water which is supplied to the boiler. Feed
water heater used to increase the efficiency. Feed water heater increases the water
temperature gradually which will reduce the predictable irreversibility incorporated with
water. The steam extracted from the stages of the cycle is used as energy to heat the feed
water. There are two types of feed water heaters. In open feed water heater the extracted
steam is in direct contact with feed water. On the other hand, closed feed water heater
passes the water through the tubes and is heated by extracted steam. Many power plant
have more than one feed water heaters and it can be open or closed depend on the type of
the power plant. The overall purpose of the feed water heater is to increase the system
efficiency.
6.2.4
Deaerator
Deaerator is generally used to remove the air and gases from the water. The
dissolve gases can harm the plant components by attaching to the walls. Water can
combines with the carbon dioxide and produce the carbonic acid which in turn causes
further corrosion. There are two types of deaerator. The deaerator can be horizontal or
vertical depend on the manufacture.

Tray type deaerator
The schematic diagram of the tray type deaerator is shown in the figure. It has
vertical deaeration section on the top of the horizontal boiler. The water feeds from the
vertical section and flows downwards. Now the low pressure steam flow upward through
the hole. The steam exits via the hole at the top of the section. The vent generally uses
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valve to allow steam to escape.
Figure 16 Tray Type Deaerator

Spray type deaerator
The spray type deaerator is shown in the figure. It is horizontal vessel which has
preheating section and deaeration section. The feed water is feed to the section E and
heated by the steam. The purpose of this section is to heat the water to its saturation
temperature. The preheated water now flows to section F. It is deaerated by the steam.
The gases striped out of the water via hole at the top of the section.
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Figure 17 Spray Type Deaerator
37
Chapter 7
SIMULATION OF COMPONENTS OF THERMAL POWER PLANT
7.1
Fluid Flow Machines
In thermal power plant, it is required to transmit the water or oil between various
components of the power plant. To provide the constant flow of the fluid pumps are
required. Sometimes fluid can be flow without the pump based on the density differences
[11].
Figure 18 Characteristic of an Ideal Water Pump [11]
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Figure 19 Characteristic of Centrifugal Water Pump [11]
The ideal pump has infinite number of shovels. Pumps establish the pressure,
velocity or fluid flow. The pump characteristic fully depends on the shape of the pump
therefore pump characteristic varies based on the type of pump. The above figure shows
the characteristic of the ideal water pump and characteristic of centrifugal water pump
with losses [11].
Pumps cause the losses due to friction, water impacts and other dynamic effects.
The following are the losses incorporated with realistic pumps [11].
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7.2

Reducing the energy

Hydraulic losses of shovel channels

Impact losses

Friction losses of impeller wheel
Pipe as an Important Part of Heat Exchanger
A pipe is the most common and important part of the fluid flow machines. The
velocity of the water depends on the roughness and cross section of the pipe. The higher
roughness decreases the velocity of the water. The following figure shows the pressure
drop in pipes versus flow velocity [11].
Figure 20 Pressure Drip in Pipes versus Flow Velocity [11]
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7.3
Heat Exchanger
Heat transfer takes place between the two materials and it is transferred based on
the temperature of these two materials. Heat transfer can be caused by convection or it
can be cause by diffusion. In standing water heat transfer takes place according to
diffusion. In thermal power plant water flows through the pipes and heat transfer takes
place between the water and pipes. It is required to define the heat transfer model for the
flowing water and pipe walls. The following figure shows the heat transfer coefficient
verses increasing flow velocity [11].
Figure 21 Heat Transfer Coefficients versus Increasing Flow Velocity [11]
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7.4
Model of Pipe
Different types of model represent the different behavior and all different types of
model require different equations. Let’s consider the infinite small pipe segment. The
velocity and pressure drop across the pipe exist due to the frictions across the pipe walls
[11]. The following figure shows the model of infinite small pipe segment. The red line
in the figure shows that the heat transfer in the axial direction is caused by diffusion [11].
Figure 22 Model of Infinite Small Pipe
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7.5
Heat Exchanger Model
Heat exchange generally takes place from high temperature material to low
temperature material. The following figure shows the parallel heat exchanger model. In
this model the fluid A has higher temperature than fluid B so heat exchange will take
place from fluid A to fluid B. Also, we need to consider the heat exchange between the
pipes in horizontal directions [11].
Figure 23Parallel Tube Heat Exchanger [11]
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Figure 24 Model of a Parallel Heat Exchanger [11]
44
Chapter 8
SCADA MODELING
There are few steps which is necessary for proper implementation of the power plant.
8.1
Important Steps for SCADA Modeling

Screening
The water from the reservoir, river or lake is not 100 percent pure. Water includes
impurities like rocks, sand, wood and many other particles which need to remove
before using this water for the plant. These materials are sent to landfill [10]

Pumping
Mostly waste water treatment plants are located below the level of the power
plant. So it is required to send this water to the plant using motors. The plant is
mostly above the level of the river or lake therefore the water needs to pumped up
to the reservoir tank [10].

Aerating
The water treatment plant shake up the mess and expose it to air. This step is
necessary to remove dissolved gases from the water. Water is passed through the
series of tanks.
First tank feeds the air into the water. Due to organic matter decays, it uses up
oxygen. Bubble passed through the oxygen allows the organic particles to settle.
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
Removing sludge & Scum
Heavy particles from the water are settled down at the bottom of the tank and
these particles are removed in a step called thickening and then the sludge is
processed in large tank known as digesters [10].
Also, some impurities are light weight. For example, oil, plastic and grease which
can easily float on the surface of the water. These impurities are removed by slow
moving rakes. Some plant also uses filtration in sewage treatment. Water is
passed through the sand which can remove the bacteria, unpleasant odors and
reduces the amount of iron. Sometime water is also passed through the carbon
particles to remove organic particles [10].
This filtered water is still have some gases like oxygen which forms oxides .These
oxides rust and cracks the boilers along with the time so whole boiler system
needs to be replaced after some period of time. This can lead to very high amount
of cost to the company. To avoid this extra cost this water send to the electro
dialysis unit where the gases are removed using some sort of techniques.
8.2
Components of the Plant
8.2.1
Valves
A valve is used to control the flow of the fluid or water. It can be operated
manually or automatically. A valve can be operated manually using wheel, paddle or
handle. An automatic valve operates based on the pressure changes. The Change in the
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pressure operates the piston and activates the valve. Also, some highly controlled
system uses actuator for controlling the valve. Depending on the controlled input valve
can be positioned accurately according to the requirement.
We have used two types of valve in our project
1. One port valves
One port valves used to allow or obstruct the flow of the fluid, water or
gases. It can allow fluid to flow along the pipes or I can stop moving the fluid.
2. Two port valves
Two port valves are also known as regulating valves because they can be
open, close or partially open. Some valves are designed to regulate the certain
amount of flow.
Here are some operations of the valves

Control : force or flow speed

closing at over speed run

over pressure prevention

back flow protection

On/Off operation
8.2.2
Aeration Tank
Aeration is used to remove the iron, manganese and other gases. The water is
47
processed in such way that It can be in more contact with air. Aeration can be done
naturally or using mechanical devices. In natural treatment water flows from the
mountain rocks to provide the more contact with air.
The aeration is used to remove the iron, volatile organic compounds and organic
material.
8.2.3
Sensors
We have used the sensors for the requirements shown below

measure the water height

measure the pressure

measure the temperature

Measure the flow speed
These sensors directly give output to the control station or it can supply the
information to the next stage. Also, sensors can be analog or digital depend on the
plant design.
8.2.4
Mesh
Mesh is generally used for the following requirements

Removal of large particles going into the motor

Removal of the plants , rocks or dead body particles
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8.2.5
Motors
Motors are used to supply the water from one stage to the next stage. For
example, Water needs to be transferred from mesh tank to the nest tank. These heavy
duty motors needs proper supervision to avoid any mishap.
8.3
Step by Step Functionality of the Project
First step of the power plant is to select the proper source of the water. The water
should be easily available. The plant should be near the river or lake so it requires less
effort to move water to the plant. Also, water should be continuously available to gain
more advantage out of the plant.
Next step is the proper storage of the water. Water can be stored in a tank or
reservoir. The water is kept for some amount of time at this stage to settle down most off
the impurities.
Now the water is moved to the tank using motors and valves. The water is also
kept here for some amount of time to remove small particle present in the water. These
tanks have some set of sensors. These sensors are used to control the flow of incoming
water. For example, if the amount of water in the tank is high then higher sensor
deactivates the valve which in turn stops the water flowing into the tank. If the water in
the tank is too low then lower sensor activates the valve and allows the water to flow into
the tank.
Then next step is to remove the impurities from the water. This step is required to
49
remove the big particles which escape from the initial tank. These particles can clog in
pipe or it can damage the motor in next stage. The mesh generally has two stages. First
stage is used to remove the large particles and second stage is used to remove the smaller
particles.
Motors are used to flow water coming from the mesh. Motors send this water to
the next tank which is used for removal of the sludge. This tank has two mode of
operation. During normal mode of operation sludge is screened from the tank by an outlet
at the bottom of the tank. During self cleaning mode the incoming and outgoing of the
water is shut down and the water inside the tank is moved with full speed to remove the
sludge which can be clog over the wall of the tank.
This water is now sent to the scum removal tank. This tank also has two modes of
operation. In normal mode, the scum is screened from the tank by an outlet at the bottom.
This water is now sent to the electro dialysis unit using motors. In self cleaning mode, the
normal supply of water is shutdown and another high speed supply of water is fed into
the tank. The water being supplied is mixed with some chemicals to kill the micro
organism in the tank.
The water coming out from the scum tank is mostly free of any visible impurities.
But this water still need electro dialysis process to remove the gases dissolved in the
water. These gases can damage the boiler parts along the period of time.
8.4
Values for the Components
We used various values for the components and animated the components using
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the SCADA software. We have also setup the alarms for the critical and warning
conditions. The values for the different components are shown below

Valves
We used two types of valves. The first valve is normal valve which is used for
one way flow control. This valve controls the input from the reservoir to the tank.
This valve has feedback system and works on the feed back of the sensor R1. This
valve is also used to control the water flow from the electro dialysis tank to the
boiler. This valve works based on the feedback of the valve v3.
Values for the valve V1 and V4
Name: V1
Description: Normal valve
High alarm: 8000
Low alarm: 500
Scan Interval: 1000 ms
Data Logging: > 9 percent
Name: V4
Description: Normal Valve
High alarm: 10000
Low alarm: 1000
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Scan interval: 1500 ms
Data logging: > 4 percent
The other type of valve is three way control valve. It is used control the flow from
the motor M1 to filter tank. This valve is control by the feedback of motor M1
and M2. The second three way valve is used for the same purpose but the input
depends on the valve V4
Name: V2
Description: Three way valve
High alarm: 10000
Low alarm: 1000
Scan interval: 1500 ms
Data logging: > 3percent
Name: V3
Description: Three way valve
High alarm: 10500
Low alarm: 1500
Scan interval: 4000 ms
Data logging: > 4 percent
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
Motors
The motors in the projects are used to pump the water to the next stage. The first
motor work based on the feedback of the sensor R2.
Name: M1
Description: Heavy duty motor
High alarm: 100
Low alarm: 15
Scan interval: 3000 ms
Data logging: > 7 percent
Base interval: 20
Name: M2
Description: Pump motor
High alarm: 200
Low alarm: 10
Scan interval: 2000 ms
Data logging: > 5 percent
Base interval: 10

Sensors
53
The sensors are used to measure the water level in tank. There are two sensors
one is high sensor and other is low sensor. These sensors sends the data to control
the valve V1 and motor M1
Name: R1
Description: level sensor
High alarm: 9000
Low alarm: 3000
Scan interval: 9000 ms
Data logging: > 8 percent
Base interval: 25
Name: R2
Description: level sensor
High alarm: 10000
Low alarm: 2500
Scan interval: 5000 ms
Data logging: > 10 percent
Base interval: 35

Tanks
54
There are two sensors in the tank to measure the level of the water and the
values of these sensors are shown below
Name: P1 or P2 or P1’ or P2’
Description: level sensor
High alarm: 9000
Low alarm: 2000
Scan interval: 8000 ms
Data logging: > 9 percent
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Chapter 9
CONCLUSION
The overall ideal of the project is to develop the future power plant in such a way that it
can not only reduce the cost of the plant but also increase the efficiency. The small
additional electro dialysis module in the plant removes the dissolved gases which can
cause the corrosion of the components. This module can avoid the extra labor cost for the
maintenance of the boiler and other components. It also saves time for installing new
components and repairing of the broken components.
In a nutshell, this project helps to build a power plant which not only provide the low cost
solution but also gives higher efficiency.
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REFERENCES
[1] SCADA Discussion
http://en.wikipedia.org/wiki/SCADA
[2] DPS Telecom version 1.2 released April 1 2008
www.dpstelecom.com
[3] http://www.integraxor.com pioneering web SCADA
[4] Sandia National Laboratories
http://www.sandia.gov/scada
[5] International system research laboratory “Technical Report TR-ISRL-04-01”
[6] Products for SCADA automated monitoring and control from CAMPBELL
SCIENTIFIC
http://www.campbellsci.com/scada
[7] Thermal power station
http://en.wikipedia.org/wiki/Thermal_power_station
[8] Modern Power Station Practice, vol 1: Planning & Layout; vol 2: Boilers, Fuel &
Ash-handling plant; vol 3: Turbines & Auxiliary Equipment, Oxford: Pergamon. ISBN 008-016436-6.
[9] Power Plant Layout: Arora, S.C. & Domkundwar, S. (1993) A Course in Power Plant
57
Engineering. Delhi: Dhanpat Rai & Sons
[10] Waste water treatment plant
http://ga.water.usgs.gov/edu/wwvisit.html
[11] Simulation of components of a thermal power plant
Arsenal Research Giefinggasse 2 1210 vienna , Austria
http://www.modelica.org/events/modelica2006/Proceedings/sessions/Session2a1.pdf
[12] SCADA system of a thermal Power plant volume 9, November 2, 2009
U.R: Analysis and command of system (ACS), ENIT
http://www.aece.ro/archive/2009/2/2009_2_14.pdf?zoom_highlightsub=optimal+design