IN THE NAME OF ALMIGHTY ALLAH, THE MOST BENEFICIAL AND
THE MOST MERCIFUL
REAL TIME MONITRORING AND SUPERVISORY CONTROL OF
DISTRIBUTION SYSTEM BASED ON GENERIC LOAD
ALLOCATION: A SMART GRID SOLUTION
By
1)
2)
3)
4)
Name
Roll No
Zain Anwer Memon (G.L)
Riaz Rasool Aamir (A.G.L)
Irshad Raheem Memon
Muhammad Ilyas Memon
09ES01
09ES103
09ES106
09ES113
Supervised by:
Dr. Bhawani Shankar Chowdhry
Co-Supervised by:
Engr. Irfan Ahmed Halepoto
Department of Electronics Engineering
Mehran University of Engineering & Technology, Jamshoro
Submitted in partial fulfillment of the requirement for the
Degree of Bachelor of Electronics Engineering
February 2013
DEDICATION
THIS HUMBLE EFFORT IS DEDICATED TO
OUR BELOVED PARENTS WHO WERE
ALWAYS THERE TO SUPPORT US
WHENEVER WE NEEDED
ENCOURAGEMENT. THEIR EFFORTS
HAVE UPLIFTED, ENCOURAGED,
INSPIRED AND GUIDED US TO THE
PEAK OF OUR SUCCESS
ii
CERTIFICATE
This is to certify that Project/Thesis Report on “REAL TIME MONITRORING AND
SUPERVISORY CONTROL OF DISTRIBUTION SYSTEM BASED ON GENERIC
LOAD ALLOCATION: A SMART GRID SOLUTION” is submitted in partial
fulfillment of the requirement for the degree of Bachelor of Electronic Engineering by the
following students:
Name of Students
Roll Nos.
1. Zain Anwer Memon (G.L)
09ES01
2. Riaz Rasool Aamir (A.G.L)
09ES103
3. Irshad Raheem Memon
09ES106
4. Muhammad Ilyas Memon
09ES113
_________________
Dr. Bhawani Shankar Chowdhry
Project/Thesis Supervisor
__________________
Dr Wajiha Shah
Chairperson
Department of Electronic Engineering
Dated: ______________
iii
ACKNOWLEDGEMENT
With deep and profound gratitude and thanks to “ALMIGHTY ALLAH” for HIS
so kindly conferring us the opportunity of undertaking and completing this project with
the right approach and complete success. All praises be to Allah, the Most Gracious and
the most Merciful, for all the blessings that He has given us, especially in completing this
project.
The most beautiful and loving, our parents, we owe them very much for their sincere
prayers, encouragement, cooperation and support in boosting our morals.
Said a wise man:
“Almost anything can be accomplished if you don’t care
Who gets the credit? When all is said and done, there remain
Many people un-thanked, un-honored and unsung”
We are like especially thankful to the support and assistance of our project
supervisor and as Dean of FEECE Dr.B.S Chowdhry for his helpful suggestions,
supervision and guidance and our co-supervisor Engr.Irfan Ahmed Halepoto. Our
chairperson Dr.Wajiha Shah for the allocation of labs, PC and other facilities for the
accomplishment of our Final year project. Our Labs staff for their cooperation during the
working hours.
Finally, we are thankful to our beloved class fellows and lab assistants who have
been source of encouragement and support throughout project.
We, the group members would like to avail this opportunity to show gratitude to
all those who came up with the valuable guidance and moral support.
iv
ABSTRACT
Energy (power) is very much important nowadays. Almost every equipment uses
electrical power. Almost every work in daily life is performed by machines or it can be
said that men are now dependent on machines. So power is the main parameter that really
needs to be managed. The Electrical power that is generated must meet the demand so
that there is no any power shortage, but here in Pakistan the main thing is that power is
not generated much that is required, also neither it is managed nor there is any check and
balance of the use of power. There are many steps that can be taken to overcome power
shortage. The general opinion is that the generation be increased; others say distributions
should be improved, but firstly there must be check and balance that how much power is
used by each of the consumer connected with substation so that the load should be
forecasted and accordingly power be generated. So we are presenting one solution
regarding distribution and load allocation to each customer that if the customer uses
power greater than the load allocated, further power is not provided and consequently that
appliance is not turned on unless the total load must not be decreased.
v
TABLE OF CONTENTS
CERTIFICATE……………………………………………………………
iii
ACKNOWLEDGEMENT………………………………………………..
iv
ABSTRACT………………………………………………………………..
v
LIST OF TABLES…………………………………………………………
x
LIST OF FIGURES………………………………………………………..
xi
LIST OF ABBREVIATION………………………………………………
xii
CHAPTER 1
1-2
INTRODUCTION
1.1
Background
1
1.2
Smart Grid Solution
1
1.3
Aims and Objectives
1-2
1.4
Summary
2
CHAPTER 2
POWER SYSTEM SCENARIO IN PAKISTAN
3-5
2.1
Electrical Network
3
2.2
Electricity Sector in Pakistan
4
2.2.1
Priorities and Principles of Load Shedding
4
2.2.2
Losses
5
CHAPTER 3
3.1
LOAD PROFILE AND MANAGEMENT
6-16
Load profile
6
3.1.1
Methodology
6
3.1.2
Primary Data Sources
6
3.1.3
2.3.2.1
Demographic information
6
3.1.2.2
Daily occupancy information
6
Generating the Load Profile
vi
6
3.1.4
3.2
3.3
An Area of Study
6
3.1.3.2
Household Type Allocation
7
3.1.3.3
Time of Use Probabilities Profiles
7
Load Profile and Forecast
7
Demand Side Management
7
3.2.1
Electricity Crisis and Demand Side Management
8
3.2.2
Causes Of Crisis
8
3.2.3
Solution to the Crisis: Demand Side Management
9
3.2.4
Load Forecast and DSM
9
Power Monitoring
9
3.3 1
What is power system monitoring?
9
3.3.2
Why to install a power monitoring system?
10
3.3.2.1
Environmental
10
3.3.2.2
Reliability
10
3.3.2.3
Maintenance
10
3.3.2.4
Safety
10
3.3.2.5
Financial
10
3.3.3
3.4
3.1.3.1
Real time remote power monitoring system
11
3.3.3.1
11
A Proposed model
SCADA
3.3.3.1.1
SCADA Features
11
3.3.3.1.2
SCADA
Subsystems
12
3.3.3.1.3
SCADA system
Operation
15
16
vii
CHAPTER 4 HARDWARE AND IMPLEMENTATION
17-33
4.1
Block diagram
17
4.2
Flow Chart
18
4.3
Hardware Components
19
4.3.1
Arduino UNO Development Board
19
4.3.1.1
Overview
19
4.3.1.2
Features
19
4.3.1.3
Power
20
4.3.1.4
Memory
21
4.3.1.5
Input and Output
21
4.3.1.6
Communications
22
4.3.1.7
Programming
22
4.3.1.8
Automatic(Software) Reset
4.3.1.9
USB Over Current Protection
23
4.3.1.10
Physical Characteristics and
Shield Commpatibility
23
4.3.1.11
Pin Mappings of the Board
23-24
With Microcontroller(Atmega328)
22-23
4.2.2
ULN2003 IC
24-25
4.2.3
Liquid Crysal Display
25-26
4.2.3.1 Pin Description
26
4.2.4
Voltage Transformer
27
4.2.5
Current Transformer
28-29
4.2.6
Diode Bridge
4.2.7
LM7805 Regulator IC
viii
29
29-30
4.4
Implementation
30-32
4.4.1 ADC Reading
32-33
4.5 Result
33
CHAPTER 5 SOFTWARE AND SIMULATION
34-40
5.1
Proteus Simulator
34-35
5.2
Current and Voltage Measuring Circuit
35-36
5.3
Programming
37-40
CHAPTER 6 CONCLUSION/FUTURE WORK
41
6.1
Conclusion
41
6.2
Future Work
41
REFERENCES
42
ix
LIST OF TABLES
Table 4.1: Arduino and Atmega328 Pin Mapping
24
Table 4.2 LCD Pin Description
26
x
LIST OF FIGURES
Fig 2.1 An Electric Network Block Diagram
3
Fig 2.2 Power Sectors In Pakistan
4
Fig 3.1 A SCADA RTU system
14
Fig 3.2 SCADA system Operation
15
Fig 4.1 Block diagram of project
17
Fig 4.2 Flow Chart of System
18
Fig 4.3 Arduino UNO Development Board
19
Fig 4.4 ULN2003 IC Internal Connection
25
Fig 4.5 Pin Configuration LCD
26
Fig 4.6 Transformer
28
Fig 4.7: Current Transformer
29
Fig 4.8 Diode Bridge Full Wave rectifier
29
Fig 4.9 LM7805 IC
30
Fig 4.10 Project Test Hardware in Breadboard
30
Fig 4.11 Real Implemented System
31
Fig 4.12 PCB Relay Interfacing Circuit
32
Fig 5.1 Schematics of the Microcontroller Circuit
33
Fig 5.2 Schematic of the Relay Interfacing Circuit
34
Fig 5.3 PCB Layout of Relay Interfacing Circuit
35
Fig 5.4: Current and Voltage Measuring Circuit
35
xi
LIST OF ABBREVIATIONS
LCD = Liquid Crystal Display
LED = Light Emitting Diode
CT = Current Transfomer
VT = Voltage Transfomer
SCADA= Supervisory Control and Data Acquisition
HMI = Human Machine Interface
RTU = Remote Terminal Unit
PLC = Programmable Logic Controller
KESC = Karachi Electric Supply Company
WAPDA = Water and Development Authority
PEPCO = Pakistan Electric Power Company
LESCO = Lahore Electric Supply Company
GEPCO = Gujranwala Electric Supply Company
FESCO = Faisalabad Electricity Supply Company
IESCO = Islamabad Electricity Supply Company
MEPCO = Manpower Export Placement Corporation
PESCO = Peshawar Electric Supply Company
HESCO = Hyderabad Electric Supply Company
QESCO = Quetta Electric Supply Company
TESCO = Tribal Electric Supply Company
SEPCO = Southern Electric Power Company
GENCO = Central Power Generation Company
NTDC = National Transmission & Despatch Company
DISCO = Power Distribution Company
JPCL = Jamshoro power Company Limited
CPGCL = Central Power Generation Company Limited
NPGCL = Northern Power Generation Company Limited
LPGCL = Lakhra Power Generation Company Limited
AC=Alternating Current
xii
CHAPTER 1
INTRODUCTION
1.1 Background:
The electrical power system in Pakistan is unpredictable, the power that is
generated at the Power Stations doesn’t meet the power requirement for the consumers,
mostly power shortage occurs whether it is winter or summer. We can’t forecast how
much power the consumer will use a day due to lack of power monitoring and
mismanagement. Let suppose the Power Company allocates a particular amount of power
to each user and therefore generates the power as required by the particular area, but there
is no any limit for any consumer that how much that consumer uses the power per day.
There is no any check and balance for power usage in any area. And almost all the
consumers use power more than they are allocated, resulting power shortage, load
shedding and overloading of distribution transformers. This causes failure of distribution
transformers which becomes very costly. Hence the power generation company cannot
generate the required amount of power for the consumers. Hence firstly we need to
monitor and forecast the power so as we come to know the power usage limit for any
area. And here we provide one solution regarding power use limitation at consumer side.
We have designed a controller that will limit the consumer not to use the power more
than allocated.
1.2 Smart Grid Solution:
“A smart grid is a modern electricity system. It uses sensors, monitoring,
communications, automation and computers to improve the flexibility, security,
reliability, efficiency, and safety of the electricity system.”[1]
In terms of our project smart grid is an automated, widely distributed energy delivery
network; the Smart Grid is characterized by a two-way of electricity and information and
will be capable of monitoring everything from power plants to customer preferences to
individual appliances. Smart grid takes in account the benefits of distributed computing
and communications to deliver real-time information and enable the near-instantaneous
balance of supply and demand at the device level. So here we present one part of smart
grid employed at consumer side to limit users to allocated power usage.
1.3 Aims and Objectives:
The main objective of this project is to limit the user for a particular load, by
controlling the power at the service main before the energy meter. Here we place two
transformers for measuring the line current and voltage, and when any device is turned
1
on, its power is measured with the help of two more voltage and current transformers.
The microcontroller measures the power in the main line and if the main line is on full
load, no any device relays are energized and hence no device turns on unless the main
line power is reduced than the maximum power.
The programming is done in C language, and the microcontroller used is
Atmega328, mounted on Arduino UNO development board.
1.4 Summary:
We studied the power system that is currently employed in Pakistan and the main
thing that we observed is that there is nothing monitored on the consumer side, we are
just generating the power and transmitting and distributing to the user without knowing
how much the consumer will use the power. Hence we started our work on this project.
The hardware, software, simulation, implementation are given in further chapters.
2
CHAPTER NO: 02
POWER SYSTEM SCENARIO IN PAKISTAN
This project is based on the power generation and distribution of load, load
forecasting and load limiting. So the electrical system is described below:
2.1 Electrical Network:
Electrical networks provide the energy to the end customers according to the
supply and demand. The power is generated at grid via different sources i-e
Hydroelectric, Gas/Coal, Fired Steam and Nuclear. Using step up Transformers, the
power is further transferred to the transmission network which is interconnected at
switching stations and substation to form a network of lines called power grid. The power
received is step downed and feed to the distribution and consumed by the users as shown
in fig 2.1.
Fig 2.1 An Electric Network Block Diagram[2]
3
2.2 Electricity Sector in Pakistan:
There are two main utilities (sectors) that is KESC(Karachi Electric
Supply Company) which served in Karachi areas and other one is WAPDA(Water and
Power Development) which serve the rest of the country. WAPDA is sub-divided into 4
GENCOs, 10 DISCOs, and one TransCO (NTDC) as shown in fig 2.2.
POWER SECTOR
WAPDA
KESC
10 DISCOs
4 GENCOs
1 TransCO
(NTDC)
PESCO
GESCO
HESCO
IESCO
LESCO
MEPCO
FESCO
QUESCO
TESCO
SEPCO
JPCL
CPGCL
NPGCL
LPGCL
Fig 2.2 Power Sectors In Pakistan[3]
2.2.1 Priorities and Principles of Load Shedding:
A distribution company shall have plans and schedules available to shed up to 30
% of its connected load at any time upon instruction from NTDC. This 30 % load must be
made up from separate blocks of switchable load, which can be disconnected in turn at
the instruction from NTDC. A distribution company shall provide its copies of these
plans to NTDC. Wherever possible NTDC shall give distribution companies advance
warning of impending need for load shedding to maintain system voltage and/or
frequency in accordance with the Grid Code. As per provisions of the Grid code, NTDC
shall maintain an overview and as required instruct each distribution company the
quantum of load to be disconnected and the time of such disconnection. The instruction
shall be given in clear, unambiguous terms and related to prepared plans. When
4
instructed by NTDC, the distribution companies shall shed the load in the following order
namely;
(a) Supply to consumer in rural areas; and residential consumers in urban areas
where separate feeders exist.
(b) Supply to consumers, other than industrial, in urban areas.
(c) Supply to agriculture consumers where there is a dedicated power supply.
(d) Supply to industrial consumers
(e) Supply to schools and hospitals
(f) Supply to defense and strategic installations.
A distribution company shall prepare schedules of load disconnection, which
demonstrate this priority order and which rotate load disconnections within the above
groups in a non-discriminatory manner. The principle of proportionality shall be kept so
as not to excessively burden a particular consumer class.
2.2.2 Losses:
Losses are estimated from the discrepancy between energy produced and energy
sold to end customers, Transmitting electricity at high voltage reduces the fraction of
energy lost to resistance.
The safe and reliable transmission and distribution of electricity remain a major
problem in Pakistan. Losses running into billions of rupees due to power theft during
transmission & distribution and billing inefficiencies. Utilities face losses due to
unmetered and unaccounted sales. The need of the hour is to devise a utility-wise
turnaround plan and monitor its implementation at the highest level in order to reduce
aggregate technical and commercial losses.
5
CHAPTER 3
LOAD PROFILE AND MANAGEMENT
3.1 Load profile:
In the Pakistan the domestic sector accounts for almost one third of the total
electricity consumption. It contributes the largest peak demand, particularly in the winter
season, which has consequences on the power Infrastructure [4] .Traditional forecasting
methods look at national energy profiles based on historic trends and thereby determining
the infrastructure requirements. Recently, energy saving methods, and embedded energy
supplies via renewable or combined heat and power, make it possible for local
communities to modify their behavior.
3.1.1 Methodology:
The identification of the pattern of energy uses of a house and the prediction
domestic load profile is an essential in order to match load shape to the power generated,
and also to predict the possible impact of any energy management action directly on the
daily load profile. The electrical load profile is based on assumptions as to the type of
electric devices including appliances and lighting, and their usage. Different households
have different lifestyles, which mean the shape of the total. Load profile will fluctuate
from house to house, and from day to day.
3.1.2 Primary Data Sources:
The inputs of the electricity demand profile generator being presented as follow:
3.1.2.1 Demographic information:
The information on the type of households is required such as the number of
adults, working people, and number of children present in house. Because the households
with children use more energy as compared to the households having no children.
3.1.2.2 Daily occupancy information:
This is the behavior of occupants in households with respect to their usage of
appliances and lighting on a daily basis. How much time the occupants use the appliances
and for what time the appliances are turned off and not in use.
3.1.3 Generating the Load Profile:
For generating load profile, following points should be considered:
3.1.3.1 An Area of Study:
6
For generating the load profile we will have to take the data from community of
households for that area. The data will be noted and observed for generating load profile
for that area and consequently load forecasting would be done.
3.1.3.2 Household Type Allocation:
To get a picture of the demographic characteristics of the area in order to allocate
different numbers of households, calculation should be based on the percentage share of
the power allocation of households. The physical location of the households is allocated
randomly using Excel’s rand function.
3.1.3.3 Time of Use Probabilities Profiles:
For generating load profile, the probability of usage times per day for devices of
each single household should be considered. In other words the behavior must be
predicted on the basis of particular community. For lighting, the winter and summer
aspects should better be considered in the modeling. For other appliances the assumption
is that the behavior may be the same.
3.1.4 Load Profile and Forecast:
Analyzing annual hourly load profiles is an important aspect of generation
planning to capture the hourly and seasonal variation in the load. The hourly loads are
used to construct the monthly load duration curves which are one of the key inputs to
generation planning. The historical monthly load duration curves are used for planning
the future years. The assumption is that the future monthly/seasonal load variations
would be very similar to the past ones. However, the historical load duration curves in the
recent years for PEPCO system cannot be directly used for future years since these curves
are restricted by supply availability. Therefore it is necessary to have information on
unrestricted monthly load patterns and hourly load profiles to represent the future years.
The load forecast is the first step for a power system master plan study. The
forecast is based on multiple regression techniques using historical data for regression
variables like electricity consumption by different categories, electricity tariffs, GDP for
different sectors, Consumer Price Index CPI, population of the country, number of
customers for different electricity tariff categories, etc[5]. The forecast presents three
scenarios low, normal and high and a scenario where the normal forecast is adjusted for
demand side management (DSM) measures.
3.2 Demand Side Management:
Demand-Side load Management (DSM) is a set of methods that co-ordinate the
activities of energy consumers and energy providers in order to realize the best adaptation
of energy production capabilities for consumer needs[6]. DSM has two perspectives on
the one hand, it has negative environmental impacts and on the other hand, it decreases
the cost of energy production. The basic kinds of DSM control are direct control that
shifts power requests by directly interrupting the high power consuming appliances and
7
Local control that consists in setting up a policy which encourages consumption at offpeak periods by reducing energy costs.
The DSM control allows energy providers to charge users for the actual energy
production cost in a more precise way. It also allows users to adjust their power
consumption according to energy price variations. In the peak period, the domestic
customer would be able to decide whether to wait and save money or to use appliances.
This strategy is more reactive than the basic DSM control but more complex to control
when comfort has to be taken into account. Energy management can be formulated as a
scheduling problem where energy is considered as a resource shared by appliances, and
periods of energy consumption are considered as tasks. DSM involves the planning and
implementation of utility activities design to influence the time pattern and amount of
electricity demand in ways that will increase customer satisfaction, and coincidentally
produce desired changes in the utilitie’s system, load shape several factors used to assess
the load desirability of specific load shape changes, including impact on system cost and
reliability. It also includes load management identification and promotion of new uses,
strategic conservations, electrification, retention, customer generation and adjustment.[6]
3.2.1 Electricity Crisis and Demand Side Management:
The electricity in Pakistan is presently facing a serious energy crisis. Despite
strong economic growth during the past decade and consequent rising demand for energy,
no worthwhile steps have been taken to install new capacity for generation of the required
energy sources. Now, the demand exceeds supply and hence load-shedding is a common
phenomenon through frequent power shutdowns. Pakistan needs about 14000-15000MW
electricity per day, and the demand is likely to rise to approximately 20,000 MW per day
by 2010. Presently, it can produce about 11, 500 MW per day and thus there is a shortfall
of about 3000-4000MW per day. This shortage is badly affecting industry, commerce and
daily life of people. The demand in the electrical energy demands in a country is
proportional to the growth in the population. If this demand is not met with the supply,
energy crisis is produced. Pakistan has been facing an unprecedented energy crisis since
last many years. This problem becomes more severe in summer and as a result shortage
of electricity is faced 8 to 10 hours in urban areas while 16 to 18 hours in rural areas. All
possible measures need to be adopted, i.e., to conserve energy at all levels, and use all
available sources to enhance production of energy. It seems that the government is
considering importing energy from Iran and Central Asian Republics and using
indigenous sources, such as, hydel, coal, waste, wind, and solar power, as well as other
alternate and renewable energy sources, besides nuclear power plants for production of
energy.
3.2.2 Causes Of Crisis:
The major management related causes of the crisis are[7]:
1. Faulty management information system
2. Failure of forecast and future planning
3. No new transmission / distribution networks and grid stations
4. Failure to set up new generating stations in time.
5. Unexpectedly rapid growth of load.
8
The problem is compounded when corrupt officials sell electricity illegally on the
black market. For instance, power theft amounts to $300 million and Up to 40 percent of
the electricity vanishes as it passes through the industrial districts. People living in the
wealthier districts tap another 10-15 percent to run their air conditioners. Such problems
caused 350 million people to suffer prolonged blackouts.
3.2.3 Solution to the Crisis: Demand Side Management
DSM is a crucial element in planning to meet the load. Such programs should be
fostered and their results taken into account as programs are implemented. NTDC has the
target to improve the load factor by employing the DSM techniques and by promoting the
Industrial share in the composition of system load. It is expected that the load factor of
the system shall improve to 71% provided the proposed DSM measures are implemented.
3.2.4 Load Forecast and DSM:
Load forecasting entails the prediction of the future level of demand, and provides
the basis for future supply side and demand side planning. Generation planning requires a
load forecast for the country as a whole, while transmission and distribution planning
requires more load–level and geographic detail to determine the location, timing and
loading of individual lines, substations and transformation facilities. Geographic load
detail is also a factor in the determination of the location of generation plants since it is
generally desirable to locate generation sources close to the load centers.
3.3 Power Monitoring:
In order to understand load profile of system we will go through general concept
regarding power monitoring system. In which we will discuss two main facts that are
given below.
1. What is power monitoring system?
2. Why power monitoring is required?
3.3 1 What is power system monitoring?
In a changing electric industry, monitoring power supply and power quality are
critical to ensuring optimal performance of power systems. Monitoring can provide
information about power flow and demand, as well as the quality of the power.
Monitoring can be a vital diagnostic tool, identifying problem conditions on a power
system before they can cause disturbances or interruptions. The concept of power quality
monitoring is related with the detection of voltage events in the mains network. The
characterization of these voltage events results from standards that define several limits
for their amplitudes, duration and maximum number of occurrences within a time period.
In the last three decades, the loads connected to the mains network suffered great
changes. The number of Electronic and sensitive equipment increased considerably, and
the old concepts of monitoring are not representative for these loads. The economical
9
impact in industrial environment as a consequence of an electrical failure, introduces the
study of power quality, and power quality monitoring.
3.3.2 Why to install a power monitoring system?
There are many benefits to installing a power monitoring system. Some of which strongly
interrelate with each other. A properly designed and installed monitoring system offers a deeper
understanding of the operational parameters of the facility's electrical system. A close appraisal of
the data generated by a monitoring system can reveal a variety of overt and subtle opportunities,
including:
3.3.2.1 Environmental:
A better knowledge of how energy is used within a facility allows you to identify
an array of prospects to improve efficiency, minimize waste, and reduce energy
consumption, thereby allowing the facility to be a better steward of its allotted natural
resources.
3.3.2.2 Reliability:
Assessment of data from the monitoring system can reveal existing or imminent
issues that can adversely affect the operation and product within a facility. Historical data
from power monitoring systems can help locate and correct both acute and chronic
problems, resulting in increased productivity.
3.3.2.3 Maintenance:
Data trends can forecast and notify the appropriate people when discrete
equipment parameters may be exceeded, allowing you to plan ahead instead of facing an
unscheduled shutdown.
3.3.2.4 Safety:
Monitoring systems can limit the exposure of personnel to potentially hazardous
electrical environments by providing remote status and operational parameters of
equipment within hazardous areas. Some monitoring devices also offer a variety of
additional parameters (temperature, pressure, flow rate, vibration, status indicators, etc.)
through the use of transducers.
3.3.2.5 Financial:
Each benefit discussed above either directly or indirectly influences a business's
bottom line. In most cases, the monetary impact from even one or two benefits can
quickly justify the purchase and installation of a power monitoring system. Additional
advantages offered by power monitoring systems may include features such as accurate
10
evaluations of spare electrical system capacity, billing allocation and validation, or
optimum placement of mitigation devices. Once you decide if a power monitoring system
makes sense in your particular situation, the next step is narrowing the field of choices.
Generally, Power monitoring systems are based upon human labor that is a line
man plays a significant role in collecting and managing field data. However, due to the
size increase of consumption areas, this kind of manual practice is considered time
consuming and labor intensive.
3.3.3 Real time remote power monitoring system:
A real time remote power monitoring systems are used to quickly identify and
resolve problems occurring on their electrical system. Power monitoring systems are
permanently installed, they operate on a 24 hours, and continuous logging of energyrelated data provides information on the operational characteristics of an electrical
system. This includes when, where and how the energy is being consumed, and what
loads are consuming the energy. This data can help you reduce the energy delivered to
and consumed by your electrical system. The quality of energy supplied to a facility can
adversely affect its operation, though leading to loss or degradation of equipment,
product, revenue, and reputation, plant managers must weight the advantages of
implementing a power monitoring program. Power monitoring systems may include
features such as accurate evaluations of spare electrical system capacity, billing allocation
and validation.
3.3.3.1 SCADA:
The term SCADA stands for Supervisory Control and Data Acquisition. A
SCADA system is a common process automation system which is used to gather data
from sensors and instruments located at remote sites and to transmit and display this data
at a central site for either control or monitoring purposes. The collected data is usually
viewed on one or more SCADA Host computers located at the central or master site. A
real world SCADA system can monitor and control hundreds to hundreds of thousands of
I/O points [8].
Common analog signals that SCADA systems monitor and control are levels,
temperatures, pressures, flow rate and motor speed. Typical digital signals to monitor and
control are level switches, pressure switches, generator status, relays & motors.
There is typically another layer of equipment between the remote sensors and
instruments and the central computer. This intermediate equipment exists on the remote
side and connects to the sensors and field instruments. Sensors typically have digital or
analog I/O and these signals are not in a form that can be easily communicated over long
distances. The intermediate equipment is used to digitize then packetize the sensor
signals so that they can be digitally transmitted via an industrial communications protocol
over long distances to the central site.
3.3.3.1.1 SCADA Features:
The main features of SCADA are :
1. Dynamic process Graphic
11
2. Alarm summery
3. Alarm history
4. Real time trend
5. Historical time trend
6. Security (Application Security)
7. Data base connectivity
8. Device connectivity
9. Scripts
10. Recipe management
3.3.3.1.2 SCADA Subsystems:
A SCADA system usually consists of the following subsystems[8]:
1) Human Machine Interface
2) A Master Unit
3) Remote terminal units (RTUs)
4) Programmable logic controller (PLCs)
3.3.3.1.2.1 Human Machine Interface:
A human–machine interface (HMI) is the device which presents process data to a
human operator, and through this, the human operator monitors and controls the process.
It is linked to the SCADA system's data bases and software programs, to provide trending,
diagnostic data, and management information such as scheduled maintenance procedures,
logistic information, detailed schematics for a particular sensor, machine and expertsystem troubleshooting guides.
The HMI system usually presents the information to the operating personnel
graphically, in the form of a mimic diagram. This means that the operator can see a
schematic representation of the plant being controlled. The HMI package for the SCADA
system includes a drawing program that the operators or system maintenance personnel
use to change the way these points are represented in the interface. A HMI has a nested
tree structure of many such screens, usually with the many overview screens on the first
page with the most relevant data displayed. Users can easily configure the type of I/O
point, communication protocol driver, polling rate, alarm thresholds and notifications,
trend process data as well as configure the User and Operator screens.
3.3.3.1.2.2 A Master Unit:
A supervisory system is a host computer or machine that acquires data on the
process and sends commands to the process. SCADA master should display information
in the most useful way to human operators and intelligently regulate your managed
systems. It contains a software responsible for communicating with the field equipment
(RTUs, PLCs, etc.), and then to the HMI software running on workstations in the control
room. The SCADA master station may includes[9]
Flexible and programmable response to sensor inputs:
Look for a system that provides easy tools for programming soft alarms (reports
12
of complex events that track combinations of sensor inputs and date/time statements) and
soft controls (programmed control responses to sensor inputs).
24/7, automatic pager and email notification:
Why pay personnel to watch a board 24 hours a day? If equipment needs human
attention, the SCADA master can automatically page or email directly to repair
technicians.
Detailed information display:
You want a system that displays reports in plain English, with a complete
description of what activity is happening and how you can manage it.
Nuisance alarm filtering:
Nuisance alarms desensitize your staff to alarm reports, and they can start to
believe that all alarms are nonessential alarms. Eventually they may stop responding even
to critical alarms. Look for a SCADA master that includes tools to filter out nuisance
alarms.
Expansion capability:
An SCADA system is a long-term investment that will last for as long as 10 to 15
years. So you need to make sure it will support your future growth for up to 15 years.
Redundant, geo-diverse backup:
The best SCADA systems support multiple backup masters in separate locations.
If the primary SCADA master fails, a second master on the network automatically takes
over, with no interruption of monitoring and control functions.
Support for multiple protocols and equipment types:
Early SCADA systems were built on closed, proprietary protocols. Single-vendor
solutions aren't a great idea as vendors sometimes drop support for their products or even
just go out of business. Support for multiple open protocols safeguards your SCADA
system against unplanned obsolescence.
3.3.3.1.2.3 Remote terminal units (RTUs):
Remote terminal units (RTUs) connecting to sensors in the process, converting
sensor signals to digital data and sending digital data to the supervisory system. It
connects to physical equipment. The RTU converts the electrical signals from the
equipment to digital values such as the open/closed status from a switch or a valve, or
measurements such as pressure, flow, voltage or current. By converting and sending these
electrical signals out to equipment the RTU can control equipment, such as opening or
closing a switch or a valve, or setting the speed of a pump. The single board RTU
normally has fixed I/O e.g. 16 digital inputs, 8 digital outputs, 8 analogue inputs, and say
4 analogue outputs. It is normally not possible to expand its capability. The modular RTU
is designed to be expanded by adding additional modules. Typical modules may be a 8
13
analog in module, a 8 digital out module. Some specialized modules such as a GPS time
stamp module may be available.
Fig 3.1 contains SCADA RTU. It is a small ruggedized computer. It has hardware
features i-e CPU, volatile memory, Nonvolatile memory for storing programs and data.
Communications capability either through serial port(s) or sometimes with an on board
modem. Secure Power supply (with battery backup). Watchdog timer (to ensure the RTU
restarts if something fails). Electrical protection against "spikes". I/O interfaces to
DI/DO/AI/AO's and Real time clock.
Fig 3.1 A SCADA RTU system [10]
RTU requires the software functionality. In many RTU's these may be
intermingled and not necessarily identifiable as separate modules i-e
Real time
operating system. This may be a specific RTOS, or it may be code that started out life as
one big loop scanning the inputs, and monitoring the communications ports. Driver for
the communications system i-e the link to the SCADA Master. Device drivers for the I/O
system i-e to the field devices. SCADA application e.g. scanning of inputs, processing
and storing of data, responding to requests from the SCADA master over the
communications network. Some method to allow the user applications to be configured in
the RTU. This may be simple parameter setting, enabling or disabling specific I/O's or it
may represent a complete user programming environment. Some RTU's may have a file
system with support for file downloads. This supports user programs, and configuration
files.
14
3.3.3.1.2.4 Programmable logic controller (PLCs):
Programmable logic controller (PLCs) used as field devices because they are
more economical, versatile, flexible, and configurable than special-purpose RTUs. PLCs
are capable of autonomously executing simple logic processes without involving the
master computer. A standardized control programming language is frequently used to create
programs which run on PLCs. Unlike a procedural language such as the C programming
language or FORTRAN has minimal training requirements by virtue of resembling
historic physical control arrays. This allows SCADA system engineers to perform both
the design and implementation of a program to be executed on PLC. A programmable
automation controller (PAC) is a compact controller that combines the features and
capabilities of a PC-based control system with that of a typical PLC. PACs are deployed
in SCADA systems to provide RTU and PLC functions. In many electrical substation
SCADA applications.
SCADA is used as a safety tool as in lock-out tag-out used to ensure that
dangerous machines are properly shut off and not started up again prior to the completion
of maintenance or servicing work. Communication infrastructure connecting the
supervisory system to the remote terminal units. Various process and analytical
instrumentation
3.3.3.1.3 SCADA system Operation:
The term SCADA usually refers to centralized systems which monitor and control
entire sites, or complexes of systems spread out over large areas. Most control actions are
performed automatically by RTUs or by PLCs. These devices employ de- facto standard
industrial data communication protocols to transmit the sensor data. The SCADA Host is
usually industrial PC running sophisticated SCADA HMI (Human Machine Interface)
software. This software is used to poll the remote sites and store the collected data as
shown in Figure 3.2. Logic can be configured in the SCADA host software which then
monitors and controls plant or equipment. The control may be automatic, or initiated by
operator commands.
Fig 3.2 SCADA system Operation
Once the data has been acquired at sent to the SCADA Host, the HMI software
will scan the acquired data. There are 3 common types of data collected i-e Analog
15
which is used for trending, Digital (on/off) which is used for alarming and Pulse (i.e.
revolutions of some kind of meter), accumulated /counted. The data is then processed to
detect preset alarm conditions, and if an alarm is present, an alarm message will flash on
the operator screen and added to an alarm list. The operator must then acknowledge this
alarm.
SCADA system may allow operators to change the set points for the flow, and
enable alarm conditions, such as loss of flow and high temperature, to be displayed and
recorded. The feedback control loop passes through the RTU or PLC, while the SCADA
system monitors the overall performance of the loop. SCADA systems implement a
distributed database, commonly referred to as a tag database, which contains data
elements called tags or points. A point represents a single input or output value monitored
or controlled by the system.
3.4 A Proposed model:
We have proposed a model that can limit the power that is allocated to any
household consumer and it can’t operate on load exceeding the allocated limit. Through
this model, no any consumer exceeds the power limit and thus the load can be forecasted
in the particular area. Also power is saved and limited and if all the consumers maintain
the power limit, we can forecast the load and generate the power accordingly. Now if any
consumer wants to use load greater than the limit then he can ask the Power Company to
increase its power limit or he should generate his own power for his further requirement.
From this there comes a smart grid solution for own power generation.
Our proposed model hardware and software implementation is discussed in
further chapters.
16
CHAPTER 4
HARDWARE AND IMPLEMENTATION
The block diagram, hardware components and system flow chart are defined in
the following sections.
4.1 BLOCK DIAGRAM:
Fig 4.1 Block diagram of project
The block diagram contains Voltage and Current Transformers (VT and CT) of
main line and devices along with Microcontroller i-e Atmega328. The current and
voltage transformers are used to measure the main line currents and voltages respectively.
17
The measured data is fed to the Analog to Digital Converter(ADC) of microcontroller.
Microcontroller is further connected to the ULN2003 IC. ULN2003 IC is a current driver
,used to drive the relay devices. Each device has its separate current and voltage
transformer for measuring the current and voltage for the device.
The system operation is done by the microcontroller through a dynamic
programming. Programming is done in such a way that if a load exceeds by a particular
mentioned load then relay of particular device may turn off the device immediately
otherwise load will remain turned on. Liquid crystal display (LCD) is also connected to
the microcontroller and that shows the current, voltage and power measured by
transformers.
The flow chart of the system defining operations in given below:
4.2 Flow chart:
Fig 4.2: Flow chart of system
18
4.3 Hardware Components:
The hardware components that we used for our project include:
1. Arduino UNO(Atmega328 Microcontroller)
2. ULN2003 IC
3. Liquid Crystal Display
4. Current Transformer
5. Voltage Transformer
6. Diode Bridge
7. LM7805(Voltage Regulator IC)
8. Potentiometers
9. Indicators
4.3.1. Arduino UNO development board
Fig 4.3 Arduino UNO Development Board[11]
4.3.1.1 Overview
The Arduino Uno is a microcontroller board based on the ATmega328(shown in figure
3.1). It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6
analog inputs, a 16 MHz ceramic resonator, a USB connection, a power jack, an ICSP
header, and a reset button. It contains everything needed to support the microcontroller;
simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter
or battery to get started.
4.3.1.2 Features:
Microcontroller
ATmega328
Operating Voltage
5V
19
Input Voltage (recommended) 7-12V
Input Voltage (limits)
6-20V
Digital I/O Pins
14 (of which 6 provide PWM output)
Analog Input Pins
6
DC Current per I/O Pin
40 mA
DC Current for 3.3V Pin
50 mA
Flash Memory
32 KB (ATmega328) of which 0.5 KB used by bootloader
SRAM
2 KB (ATmega328)
EEPROM
1 KB (ATmega328)
Clock Speed
16 MHz
4.3.1.3 Power
The Arduino Uno can be powered via the USB connection or with an external power
supply. The power source is selected automatically.
External (non-USB) power can come either from an AC-to-DC adapter (wall-wart) or
battery. The adapter can be connected by plugging a 2.1mm center-positive plug into the
board's power jack. Leads from a battery can be inserted in the Gnd and Vin pin headers
of the POWER connector.
The board can operate on an external supply of 6 to 20 volts. If supplied with less than
7V, however, the 5V pin may supply less than five volts and the board may be unstable.
If using more than 12V, the voltage regulator may overheat and damage the board. The
recommended range is 7 to 12 volts.
The power pins are as follows:
4.3.1.3.1 VIN: The input voltage to the Arduino board when it's using an external power
source (as opposed to 5 volts from the USB connection or other regulated power source).
You can supply voltage through this pin, or, if supplying voltage via the power jack,
access it through this pin.
4.3.1.3.2 “5V”:This pin outputs a regulated 5V from the regulator on the board. The
board can be supplied with power either from the DC power jack (7 - 12V), the USB
connector (5V), or the VIN pin of the board (7-12V). Supplying voltage via the 5V or
3.3V pins bypasses the regulator, and can damage your board. We don't advise it.
4.3.1.3.3 “3V3”: A 3.3 volt supply generated by the on-board regulator. Maximum
current draw is 50 mA.
4.3.1.3.4 GND: Ground pins.
20
4.3.1.3.5 IOREF: This pin on the Arduino board provides the voltage reference with
which the microcontroller operates. A properly configured shield can read the IOREF pin
voltage and select the appropriate power source or enable voltage translators on the
outputs for working with the 5V or 3.3V.
4.3.1.4 Memory
The ATmega328 has 32 KB (with 0.5 KB used for the bootloader). It also has 2 KB of
SRAM and 1 KB of EEPROM (which can be read and written with the EEPROM
library).
4.3.1.5 Input and Output
Each of the 14 digital pins on the Uno can be used as an input or output,
using pinMode(), digitalWrite(), and digitalRead() functions. They operate at 5 volts.
Each pin can provide or receive a maximum of 40 mA and has an internal pull-up resistor
(disconnected by default) of 20-50 kOhms. In addition, some pins have specialized
functions:
1. Serial: 0 (RX) and 1 (TX). Used to receive (RX) and transmit (TX) TTL serial
data. These pins are connected to the corresponding pins of
the ATmega8U2 USB-to-TTL Serial chip.
2. External Interrupts: 2 and 3. These pins can be configured to trigger an interrupt
on a low value, a rising or falling edge, or a change in value. See
the attachInterrupt() function for details.
3. PWM: 3, 5, 6, 9, 10, and 11. Provide 8-bit PWM output with
the analogWrite() function.
4. SPI: 10 (SS), 11 (MOSI), 12 (MISO), 13 (SCK). These pins support SPI
communication using the SPI library.
5. LED: 13. There is a built-in LED connected to digital pin 13. When the pin is
HIGH value, the LED is on, when the pin is LOW, it's off.
6. The Uno has 6 analog inputs, labeled A0 through A5, each of which provide 10
bits of resolution (i.e. 1024 different values). By default they measure from
ground to 5 volts, though is it possible to change the upper end of their range
using the AREF pin and the analogReference() function. Additionally, some pins
have specialized functionality:
7. TWI: A4 or SDA pin and A5 or SCL pin. Support TWI communication using
the Wire library.
8. There are a couple of other pins on the board:
9. AREF. Reference voltage for the analog inputs. Used with analogReference().
10. Reset. Bring this line LOW to reset the microcontroller. Typically used to add a
reset button to shields which block the one on the board.
21
4.3.1.6 Communication
The Arduino Uno has a number of facilities for communicating with a computer, another
Arduino, or other microcontrollers. The ATmega328 provides UART TTL (5V) serial
communication, which is available on digital pins 0 (RX) and 1 (TX).
An ATmega16U2 on the board channels this serial communication over USB and appears
as a virtual com port to software on the computer. The '16U2 firmware uses the standard
USB COM drivers, and no external driver is needed. However, on Windows, a .inf file is
required. The Arduino software includes a serial monitor which allows simple textual
data to be sent to and from the Arduino board. The RX and TX LEDs on the board will
flash when data is being transmitted via the USB-to-serial chip and USB connection to
the computer (but not for serial communication on pins 0 and 1).
A SoftwareSerial library allows for serial communication on any of the Uno's digital
pins.
4.3.1.7 Programming
The Arduino Uno can be programmed with the Arduino software (download).
Select "Arduino Uno from the Tools > Board menu (according to the microcontroller on
your board).
The ATmega328 on the Arduino Uno comes preburned with a bootloader that allows you
to upload new code to it without the use of an external hardware programmer. It
communicates using the original STK500 protocol (reference, C header files).
You can also bypass the bootloader and program the microcontroller through the ICSP
(In-Circuit Serial Programming) header; see these instructions for details.
The ATmega16U2 (or 8U2 in the rev1 and rev2 boards) firmware source code is
available . The ATmega16U2/8U2 is loaded with a DFU bootloader, which can be
activated by:
On Rev1 boards: connecting the solder jumper on the back of the board (near the map of
Italy) and then resetting the 8U2.
On Rev2 or later boards: there is a resistor that pulling the 8U2/16U2 HWB line to
ground, making it easier to put into DFU mode.
4.3.1.8 Automatic (Software) Reset
Rather than requiring a physical press of the reset button before an upload, the
Arduino Uno is designed in a way that allows it to be reset by software running on a
connected computer. One of the hardware flow control lines (DTR) of
22
theATmega8U2/16U2 is connected to the reset line of the ATmega328 via a 100
nanofarad capacitor. When this line is asserted (taken low), the reset line drops long
enough to reset the chip. The Arduino software uses this capability to allow you to upload
code by simply pressing the upload button in the Arduino environment. This means that
the bootloader can have a shorter timeout, as the lowering of DTR can be wellcoordinated with the start of the upload.
This setup has other implications. When the Uno is connected to either a computer
running Mac OS X or Linux, it resets each time a connection is made to it from software
(via USB). For the following half-second or so, the bootloader is running on the Uno.
While it is programmed to ignore malformed data (i.e. anything besides an upload of new
code), it will intercept the first few bytes of data sent to the board after a connection is
opened. If a sketch running on the board receives one-time configuration or other data
when it first starts, make sure that the software with which it communicates waits a
second after opening the connection and before sending this data.
The Uno contains a trace that can be cut to disable the auto-reset. The pads on either side
of the trace can be soldered together to re-enable it. It's labeled "RESET-EN". You may
also be able to disable the auto-reset by connecting a 110 ohm resistor from 5V to the
reset line.
4.3.1.9 USB Overcurrent Protection
The Arduino Uno has a resettable polyfuse that protects your computer's USB
ports from shorts and overcurrent. Although most computers provide their own internal
protection, the fuse provides an extra layer of protection. If more than 500 mA is applied
to the USB port, the fuse will automatically break the connection until the short or
overload is removed.
4.3.1.10 Physical Characteristics and Shield Compatibility
The maximum length and width of the Uno PCB are 2.7 and 2.1 inches
respectively, with the USB connector and power jack extending beyond the former
dimension. Four screw holes allow the board to be attached to a surface or case. Note that
the distance between digital pins 7 and 8 is 160 mil (0.16"), not an even multiple of the
100 mil spacing of the other pins.
4.3.1.11 Pin Mappings of the Board with Microcontroller
The pin mapping for the board with microcontroller is shown in the following
table.
23
Table 4.1: Arduino and Atmega328 Pin Mapping
Arduino
UNO
function
Reset
Arduino
UNO
function
Analog
Input 5
Analog
Input 4
Analog
Input 3
Analog
Input 2
Analog
Input 1
ATMEGA 328 PIN
PC6(PCINT14/Reset)
Digital
PIN 0(RX)
Digital
PIN 1(TX)
Digital
PIN 2
Digital
PIN
3(PWM)
Digital
PIN 4
VCC
GND
PD0(PCINT16/RXD)
PD3(PCINT19/OC2B/INT1)
Crystal
Crystal
PB6(PCINT6/XTAL1/TOSC1)
PB7(PCINT7/XTAL2/TOSC2)
Digital
PIN
5(PWM)
Digital
PIN 6
PD5(PCINT21/OC0B/T1)
PD1(PCINT17/TXD)
PD2(PCINT18/INT0)
PD4(PCINT20/XCK/T0)
VCC
GND
PD6(PCINT22/OC0A/AIN0)
Digital
PIN 7
PD7(PCINT23/AIN1)
Digital
PIN 8
PB0(PCINT0/CLCO/ICP1)
ATMEGA 328 PIN
PC5(ADC5/PCINT13)
PC4(ADC4/PCINT12)
PC3(ADC3/PCINT11)
PC2(ADC2/PCINT10)
PC1(ADC1/PCINT9)
Analog
Input 0
GND
Analog
Reference
VCC
Digital PIN
13
Digital PIN
12
PC0(ADC0/PCINT8)
Digital PIN
11
(PWM)
Digital PIN
10
PWM
Digital PIN
9
PWM
PB3(MOSI/OC2A/PCINT3)
GND
AREF
AVCC
PB5(SCK/PCINT5)
PB4(MISO/PCINT4)
PB2(SS/OC1B/PCINT2)
PB1(OC1A/INT1)
4.3.2 ULN2003:
The ULN2003 is a monolithic high voltage and high current Darlington transistor
arrays. It consists of seven NPN darlington pairs that features high-voltage outputs with
common-cathode clamp diode for switching inductive loads.
24
Fig 4.4 ULN2003 IC Internal Connection[13]
The collector-current rating of a single darlington pair is 500mA. The darlington pairs
may be paralleled for higher current capability. Applications include relay drivers,
hammer drivers, lamp drivers, display drivers(LED gas discharge),line drivers, and logic
buffers. The ULN2003 has a 2.7kW series base resistor for each Darlington pair for
operation directly with TTL or 5V CMOS devices. Its internal connection is shown in
figure 3.2
4.3.3 Liquid Crystal Display
LCD (Liquid Crystal Display) screen is an electronic display module and find a
wide range of applications. A 16x2 LCD display is very basic module and is very
commonly used in various devices and circuits. These modules are preferred over seven
segments and other multi segment LEDs. The reasons being: LCDs are economical;
easily programmable; have no limitation of displaying special & even custom characters
(unlike in seven segments), animations and so on.
A 16x2 LCD means it can display 16 characters per line and there are 2 such lines(shown
in figure 3.3). In this LCD each character is displayed in 5x7 pixel matrix. This LCD has
two registers, namely, Command and Data.
The command register stores the command instructions given to the LCD. A command is
an instruction given to LCD to do a predefined task like initializing it, clearing its screen,
setting the cursor position, controlling display etc. The data register stores the data to be
displayed on the LCD. The data is the ASCII value of the character to be displayed on the
LCD.
25
Fig 4.5 Pin Configuration 16*2 LCD
4.3.3.1 Pin Description:
The pin description for the LCD is given in the table below:
Table 4.2 LCD Pin Description
Pin
No
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Function
Name
Ground (0V)
Supply voltage; 5V (4.7V – 5.3V)
Contrast adjustment; through a variable resistor
Selects command register when low; and data register when
high
Ground
Vcc
VEE
Register Select
Low to write to the register; High to read from the register
Sends data to data pins when a high to low pulse is given
Read/write
Enable
DB0
DB1
DB2
DB3
DB4
DB5
DB6
DB7
Led+
Led-
8-bit data pins
Backlight VCC (5V)
Backlight Ground (0V)
RS, register select
There are two very important registers inside the LCD. The RS pin is used for their
selection as
follows.
 If RS = 0, the instruction command code register is selected, allowing the user
to send a command such as clear display, cursor at home, etc.
26

If RS = 1, the data register is selected, allowed the user to send data to be
displayed on the LCD.
R/W, read/write
R/W input allows the user to write information to the LCD or read information from it.
R/W = 0 when writing, R/W = 1 when reading. For most applications, there really is no
reason to read from the LCD. R/W is usually tied to ground.
EN, enable
The enable pin is used by the LCD to latch information presented to its data pins. When
data is
supplied to data pins, a high-to-low pulse must be applied to this pin in order for the LCD
to
latch in the data present at the data pins (data is written to the LCD at the falling edge of
the EN
line).
Data, DB7 – DB0
 The 8-bit data pins, DB7-DB0, are used to send information (data-ASCII code, or
LCD command) to the LCD.
 To display letters or numbers, we send ASCII codes for the letter s A-Z, a – z, and
numbers 0-9 to these pins while making RS = 1.
 To send instruction command codes, the following command codes can be sent to
LCD while making RS = 0.
4.3.4
Voltage Transformer
Voltage transformers are widely used in power distribution systems. They step up
or step down the voltage according to the need of the system. There are two windings
namely primary and secondary. It works on the Faradays Law of Electromagnetic
Induction that states that “any change in the magnetic environment of a coil of wire will
cause a voltage (emf) to be induced in the coil. No matter how the change is produced,
the voltage will be generated. The change could be produced by changing the magnetic
field strength, moving a magnet towards or away from the coil, moving the coil into or
out of the magnetic field, rotating the coil relative to the magnet, etc”.
Both wires in a transformer are actually wrapped in a coil around an iron core(as
shown in figure 4.6). The iron core is immersed in an insulating oil bath which does not
conduct electricity well. The coils of wire are not physically connected. One wire has
more turns in its coil than the other wire. The different numbers of coils in the two wires
causes the voltage and current in each wire to be different from the other wire. By
designing the transformer with just the right number of coils in each wire, electrical
engineers can control exactly how much the transformer changes the voltage from the
incoming to the outgoing wire.
27
Fig 4.6 Transformer
Transformers only work with AC (alternating current) circuits. Since the AC current on
the "incoming" wire is constantly changing, the magnetic field it creates changes too. The
changing magnetic field is what forces current to flow in the "outgoing" wire.
Transformers are passive devices - they don't add power. A high voltage and low current
exits the transformer carrying almost the same amount of power along the transmission
lines that the incoming low voltage and high current did. Transformers are very efficient.
Under normal conditions they transmit about 99% of the power that enters them (about
1% of the power is lost as heat).
4.3.5
Current Transformer:
A current transformer (CT) is used for measurement of electric currents. Current
transformers, together with voltage transformers (VT) (potential transformers (PT)), are
known as instrument transformers. When current in a circuit is too high to directly apply
to measuring instruments, a current transformer produces a reduced current accurately
proportional to the current in the circuit, which can be conveniently connected to
measuring and recording instruments. A current transformer also isolates the measuring
instruments from what may be very high voltage in the monitored circuit. Current
transformers are commonly used in metering and protective relays in the electrical power
industry.
The current transformer used to measure current in main line, and also to measure
the current that the load takes. For that we have used 3 current transformers in our
project. Current transformer is shown in fig 4.7
28
Fig 4.7: Current Transformer
4.3.6
Diode Bridge
A diode bridge is an arrangement of four (or more) diodes in a bridge
circuit configuration that provides the same polarity of output for either polarity of input.
When used in its most common application, for conversion of an alternating current (AC)
input into a direct current (DC) output, it is known as a bridge rectifier. A bridge rectifier
provides full-wave rectification from a two-wire AC input, resulting in lower cost and
weight. The essential feature of a diode bridge is that the polarity of the output is the
same regardless of the polarity at the input. Diode bridge is shown in fig 4.8 below
Fig 4.8 Diode Bridge Full Wave rectifier
4.3.7
Regulator IC LM7805
This is a 5 volts regulator IC of the series LM78XX. The LM78XX series of three
terminal regulators is available with several fixed output voltages making them useful in
a wide range of applications. One of these is local on card regulation, eliminating the
distribution problems associated with single point regulation. The voltages available
allow these regulators to be used in logic systems, instrumentation, HiFi, and other solid
state electronic equipment. Although designed primarily as fixed voltage regulators these
devices can be used with external components to obtain adjustable voltages and currents.
It is a 3 terminal IC as shown in fig 4.9,having output current up to 1.5 A.
29
Fig 4.9 LM7805 IC
4.4 Implementation:
Before making a model of this system, firstly the microcontroller was programmed
and tested on the breadboard to see the main working of the controller. And the errors
and problems were solved. The system test hardware on breadboard is shown in the
following figure 4.10.
Fig4.10: Project Test Hardware in Breadboard
For all the hardware components, a panel is made where all the components are
assembled and connected together, as shown in fig 4.11.
30
Fig 4.11 Real Implemented System
There are two power sockets given for the load where any device can be connected to
make it operate. There are total of 7 transformers connected, of which one voltage
transformer is for power supply, 3 voltage transformers for voltage measurement and 3
current transformers for current measurement. After each transformer there is Diode
Bridge that converts AC voltage to DC. The current is also measured in terms of voltage.
The measured voltage and current are in the range of 0-5 Volts DC. These measured
voltages and currents are given to the analog inputs (ADC inputs) of the microcontroller.
The microcontroller takes the product of voltage and current to calculate the power in the
line. If the main line is running on full load (threshold), then the RED indicator glows
showing that the main line is already on full load and no device can be turned on, if the
main line is under load, green indicator glows showing that further devices can be turned
on. When any device is connected on the power socket, and switched on, initially its relay
is on, now the current and voltage is measured through microcontroller and added to the
31
main line, if the main line exceed the threshold, the relay for that device is energized and
the contact is open and the device doesn’t operate irrespective of its power switch. If the
main line does not exceed the threshold the relay is left uncharged and the device
operates. This way the main line in any way doesn’t exceed the power limit (here we
have power limit of 2 KW).
For relay operation through microcontroller, we have used ULN2003 to
regulate/maintain the current to each relay for energizing. The PCB circuit for ULN2003
and relay operating is shown in following fig 4.12.
Fig 4.12 PCB Relay Interfacing Circuit
4.4.1
ADC Reading:
The transformers measure the current and transformer scaled upto 0-5 Volts DC,
when this signal is applied to ADC of the microcontroller, the ADC output value is in the
32
binary value, so in order to calculate the original analog signal, we apply the following
formula:
Analog value = (Vref*ADC value) /resolution(max adc value)
And here we have 5 volts reference value and resolution is 10 bit, so max adc value is
1024. So the formula we used to calculate analog input value from transformers is
Analog input Voltage =48*( (5*ADC value)/1024)
Analog input Current = 2*( (5*ADC value)/1024)
4.5 Result:
When the main line is running on 1 Kw load Green indicator glows which shows
the main line is under load and further load can be derived. Now suppose we turn on a
device of 100 watt, it is turned on because the main line doesn’t exceed the load limit.
But if we try to turn on a load of 1 Kw when main line is already on 1.1 Kw,
microcontroller measures its power and since turning this load on will make the main line
2.1 kw which is more than the allocated load(i-e 2 Kw), hence the microcontroller
energizes the relay for that device and the load is disconnected from the phase. This way
the devices that make derive the load making main line greater than load limit, are not
switched on and this way the main line in anhy way doesnot exceeds the allocated load.
33
CHAPTER 5
SOFTWARE AND SIMULATION
The softwares used for the project are:
1.
2.
3.
4.
Protues 7(Simulator)
Multisim
ARES(PCB Design)
Arduino Development Software(Programming)
5.1 Protues 7(Circuit Simulator)
Protues is a circuit simulator that is used to draw circuit schematics and also to
simulate the circuit before implementing so that the developer observes circuit
operation and to correct errors if any.
For our project, we programmed the microcontroller and then simulated the test
circuit by placing the potentiometers in place of current and voltage measurement
transformers to see how the circuit works. The circuit schematics of microcontroller
with LCD and potentiometers is shown below in fig 5.1
Fig 5.1 Schematics of the Microcontroller Circuit
34
Now for relay operating through microcontroller, we have made separate circuit that
is connected with the outputs of the microcontroller, it uses ULN2003 IC. Schematic
for the interfacing circuit is shown below in figure 5.2.
Fig 5.2 Schematic of the Relay Interfacing Circuit
As microcontroller is embedded on the Arduino UNO kit, so we didn’t need to go
for PCB of this circuit but we made the PCB for the relay interfacing with the
microcontroller through ULN2003, shown in figure 5.2
4.1 Current and Voltage Measuring Circuit:
For measuring current and voltage, CT and VT are used that scale down the actual
values and then rectified so as to measure those values on ADC. The schematic is
given below in figure 4.4.
35
Fig 5.3 PCB Layout of Relay Interfacing Circuit
Fig 5.4: Current and Voltage Measuring Circuit
36
4.2 Programming:
The programming is done in C language through Arduino Alpha development software.
Programming code is given below:
#include <LiquidCrystal.h>
// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
//device 1 input
int input_voltage1 = A0;
int input_current1 = A1;
//device 2 input
int input_voltage2 = A2;
int input_current2 = A3;
//main line input
int main_voltage = A4;
int main_current = A5;
int relay1 = 8; //outptu relay for device 1
int relay2 = 9; //output relay for device 2
int led = 10; //output status for main line
float v1 = 0; // variable to store the ADC value coming from the analog inputs
float i1 = 0;
float v2 = 0;
float i2 = 0;
float v = 0;
37
float i = 0;
float voltage1; //variable to store the analog input values
float current1;
float voltage2;
float current2;
float voltage;
float current;
float power1; //variables for power
float power2;
float main_power;
void setup() {
// declare the relay pins as outputs:
pinMode(relay1, OUTPUT);
pinMode(relay2, OUTPUT);
pinMode(led, OUTPUT);
// set up the LCD's number of columns and rows:
lcd.begin(16, 2);
}
void loop() {
lcd.setCursor(0,1);
lcd.print("M.Power: ");
// read the value from the inputs
38
v1 = analogRead(input_voltage1); //digital value from ADC input (1010100010)
i1 = analogRead(input_current1);
v2 = analogRead(input_voltage2);
i2 = analogRead(input_current2);
v = analogRead(main_voltage);
i = analogRead(main_current);
voltage1 = 48*((5*v1)/1024); //calculate analog value from digital value...reference
voltage 5 volts, resolution 10 bits
current1 = 2*((5*i1)/1024);
power1 = voltage1*current1;
voltage2 = 48*((5*v2)/1024); //calculate analog value from digital value...reference
voltage 5 volts, resolution 10 bits
current2 = 2*((5*i2)/1024);
power2 = voltage2*current2;
voltage = 48*((5*v)/1024); //calculate analog value from digital value...reference
voltage 5 volts, resolution 10 bits
current = 2*((5*i)/1024);
main_power = voltage*current;
if((main_power + power1)>=2000)
digitalWrite(relay1,LOW);
else digitalWrite(relay1,HIGH);
39
if((main_power + power2)>=2000)
digitalWrite(relay2,LOW);
else digitalWrite(relay2,HIGH);
if(main_power>=2000)
digitalWrite(led, HIGH);
else digitalWrite(led, LOW);
lcd.setCursor(0,0); //set LCD cursor 1st row 1st column
// Print a values to the LCD.
lcd.print(power1);
lcd.print(" W");
lcd.setCursor(9,0);
lcd.print(power2);
lcd.print(" W");
lcd.setCursor(9,1);
delay(500);
lcd.print(main_power);
lcd.print(" W");
}//end
40
CHAPTER 6
CONCLUSION AND FUTURE WORK
6.1 Conclusion
Through this project, we tried to improve the electrical power monitoring and
load forecasting by applying the method of load limiting at consumer side. If this system
is employed in Pakistan, the Electrical Power Company can have better view about the
load usage of each household per day and consequently load forecasting can be done,
which will result in the power generation meeting the consumer demand. Hence many
problems that occur in today’s society, like power shortage, load shedding, transformer
overloading, can be solved.
6.2 Future Advancements
There can be many features added to the system, like we can make a database of
all the households on daily basis, smart grid additions can be done. We can add the
feature that when any household consumer wants to consume load more than allocated
then he can generate his own power. Real time monitoring can be added, smart metering
can be employed with this system which will monitor all the parameters on the main line.
Programming in C language can be done in java by which monitoring system software
can be designed. This system will prove much efficient in future and we will have much
less power deficient Pakistan.
41
REFERENCES
[1] Canadian Electricity Association, A discussion paper ‘The smart grid, a programmatic
approach”, released on March 25, 2010.pp 5-6
[2] Ken Barne, Briam Johnson ”Introduction To SCADA Protection And Vulnerabilities”
, idaho National Engineering and Environmental Laboratory
Bechtel BWXT Idaho, LLC, released on March 2004, chapter 01 pp 1-6
[3]A Report on “An Overview of Electricity Sector In Pakistan”, Chamber of commerce
& industry , Islamabad, released in 2011,pp 3-5
[4] V. Hamidi, F. Li, F. Robinson, Demand response in the UK’s domestic sector,
Electric Power Systems Research 79 ,released in 2009 ,1722-1726, pp1-3
[5]NTDC, Electricity demand forecast Based on Regression Analysis
(Period 2008 to 2030), pp 19-22
[6] Fikri Prof Dr. Zahir Ahmed , “Introduction of new technologies for renewables and
demand side management in the power sector in Pakistan”,paper no.261,released in 2008
, pp 37-39
[7] Dr,M. Arshad Javaid1, Sarfraz Hussain, Abdul-Maqsood, Dr. Zeba Arshad,
Dr. M.Awais Arshad , Majid Idrees, “Electrical Energy Crisis in Pakistan and Their
Possible Solutions”, International Journal of Basic & Applied Sciences IJBAS-IJENS
Vol: 11 No: 05, 110505-9393 IJBAS-IJENS , published in October 2011 IJENS, pp 39
[8] Marek Zima and Marija Boˇckarjova, “Operation, Monitoring and
Control Technology of Power Systems”, Lecture 227-0528-00, ITET ETH, March 2007,
pp 26-29
[9] DPS Telecom , “A Quick, Easy, Comprehensive Guide on SCADA Tutorial’,
Version 2.0 ,Released August 8, 2011
[10] http://members.iinet.net.au/~ianw/rtu.html , Last excess date :Feb 04, 2013
[11] http://arduino.cc/en/Main/ArduinoBoardUno Last excess date : Feb 04, 2013
42