Auto Power Supply Control From Four Different Sources
( Solar,Wind,Main and Generator)
To ensure No Power Interruptions.
Abdimalik, Abdikarim,Mubarik,Khadan,Saynab,Ridwan and
Ahmed
Department of Electrical Engineering
University Of Hargeisa
Hargeisa, Somaliland
Year: 2019
i
Certificate of originality
We hereby declare that this report, submitted to the College of Engineering
of the University of Hargeisa as a partial fulfillment of the requirements for
the Energy conversion and rural electrification course in Electrical
Engineering has been submitted as an exercise in the university.
We also certify that the work described here is entirely our own except for
excerpts and summaries whose sources are appropriately cited in the
references. This report may be made available within the university library
for the purposes of consultation.
Date: 20-january-2019
1:- Abdikarim Awale Dool ID : 1512094
________________________________
2:-Abdimalik Mohamed Mecad ID: 1512681
_______________________________
3:-Mubarki Yuusuf Ibrahim ID: 1512781
________________________________
4: Saynab Hassan Nuh ID: 1513149
_____________________________
5: Khadan Abdi Muhumed ID: 1513215
____________________________________
6: Ahmed Abdisamed Abdilahi ID:1512034
___________________________________
7: Ridwan Mukhtar Dayib ID : 1512952
___________________________________
ii
Approval sheet
This is to certify that this project report entitled “Auto power
supply control from four different sources such as main, solar,
inverter, generator
intended to Hargeisa Group Hospital”
submitted by:
1: Abdikarim Awale Dool ID : 1512094
2:Abdimalik Mohamed Mecad ID: 1512681
3:Mubarik Yuusuf Ibrahim ID: 1512781
4: Saynab Hassan Nuh ID: 1513149
5: Khadan Abdi Muhumed ID: 1513215
6: Ahmed Abdisamed Abdilahi ID:1512034
7: Ridwan Mukhtar Dayib ID : 1512952
In partial fulfillment of the requirements for the degree of
Bachelor of Science in Electrical Engineering of the College of
Engineering, University of Hargeisa during the academic year
2018-19 has been accepted.
Supervisor: Bewnet Getachew
Signature: _______________
Date: ___________________
iii
Acknowledgement
We would like to express our sincere gratitude
towards all the people who have contributed their
precious time and effort to help us, without them it
would have been a great difficulty for us to
understand and complete the project.
We would especially like to thank our supervisor
Eng Bewnet Getachew, for his guidance, support,
motivation, and encouragement throughout the
period this work was carried out. His readiness for
consultation at all times, his educative comments,
his concern, and assistance even with practical
things have been invaluable.
iv
ABSTRACT
The main objective of this project is to provide uninterrupted power supply to a
load, by selecting the supply source automatically from any available one out
of 4 such as: mains, generator, inverter and solar in the absence of power
supply. The demand for electricity is increasing every day and frequent power
cut is causing many problems in various areas like industries, hospitals and
houses. An alternative arrangement for power source is thus desirable.
This project employs four switches to demonstrate / activate respective failure
of the source of power supply. When any of the switches is pressed, it shows
the absence of that particular source. Switches are connected to the
microcontroller as input signals. A microcontroller of the PIC16F8 family is
used. The output of the microcontroller is given to the relay driver IC, which
switches appropriate relay to maintain uninterrupted supply to the load. Output
is observed using a lamp drawing power from the mains initially. On the
failure of the mains supply (which is actuated by pressing appropriate switch)
the load gets supply from the next available source i.e. an inverter. If the
inverter also fails, it switches over to the next available source, and so on. The
current status, like which source is supplying power to the load is also
displayed on an LCD. As it is not feasible to provide all 4 different sources of
supply, one source with an alternate parallel arrangement is provided to get the
same function for demo purposes. However 4 different sources if available
they can be used.
The project can be further enhanced by using other sources like wind power
also, and then can take into consideration the best possible power source – the
one whose tariff remains lowest at a given moment.
v
Content table
Certificate of originality …………………………………………………………i
Approval sheet ……………………………………………………………………..ii
Acknowledgement………………………………………………………………..iii
ABSTRACT…………………………………………………………………………….iv
1. Introduction……………………………………………..1
1.1 Motivation……………………………………………1
1.2 Statement of the problem ……………………………..2
1.3 Objective of the project……………………………….2
1.4 Limitation of the project………………………………3
1.5 Organization of documentation……………………….3
2. Literature review...............................................................4
2.1 Definitions………………………………………………4
2.2 Diagrams………………………………………………5
2.2.1 Schematic circuit diagram……………………………5
2.2.2 Block diagram ………………………………………..6
2.3 components……………………………………………7
2.4 working principle ……………………………………..8
2.5 advantages …………………………………………….9
2.6 disadvantages………………………………………….9
2.7 Applications…………………………………………..9
2.8 Scope of the project…………………………………..10
3
Analysis and Design…………………………………11
3.1 Analysis………………………………………………11
vi
3.2 Design………………………………………………..12
3.2.1 Programming……………………………………….12
3.2.2 Hardware requirement…………………………… ..13
3.3 Recommended Solar System…………………………..13
3.3.1 Solar system ………………………………………….13
3.3.2 Overview……………………………………………...13
3.3.3 Stand-Alone Solar system…………………………….14
3.4 Solar system components………………………………15
3.5 Solar system sizing……………………………………. 18
4. Conclusion………………………………………………..21
Reference……………………………………………………22
Appendix A………………………………………………….23
Appendix B………………………………………………….24
vii
CHAPTER ONE
INTRODUCTION
1.1 MOTIVATION
In this modern time the electricity became a part of life as there are more and
more electronic and electrical machines around us which we use various
ways.These electronics changed the way we life by easing communication and
transport of the humans. Despite these technological victories, there is a problem
of electricity and its utilization in many countries.
In Somaliland the electrical energy is expensive in terms of cost that makes
Somaliland one of the highest electricity payment around the world. The average
cost of Somaliland electricity is $0.79kWh where the world’s average cost of
electricity is between ($0.15 up to$0.30).This is due to usage of diesel
generating methods that consume fuel which is also an expensive energy.
We need to think of the energyresources that our country is rich like the sunlight
intensity and the wind. If we install windmills and solar panels in the country we
can harvest the clean and cheap electricity which will drive the industries and
businesses in the country.
If foreign investors find a cheap electricity in our country they may fund or
move large scale industries into our country where we can find hundreds or
thousands of jobs and it will be the beginning of economic growth in
Somaliland.
To achieve all above suggestion we must improve the usage and utility of the
electricity into new means by analyzing the obstacles that opposed our power
energy and also try to solve or minimize the impact of the problem .
Every system has its weaknesses whether they are minimum or not, it is a must
to solve that limitations as much as we can. If there is no challenges then there
will not be new inventions because it was already said “the necessity is the
mother of invention” which means after the problems arise, solution may be
created.
After these developments arrive there will be a need of control systems that
improve the existing systems and also rise the quality of new systems. These
control systems can be such as our topic’s one “Auto power supply control from
4 different sources”, that we are going to overcome the challenges of power
breaks in some places which use interconnected electricity sources.
1
Auto power supply control from different sources will help the commercial
sites, industries,hospitals,homes, government institution and also educational
places to get uninterrupted and reliable electricity from their interconnected grid
electricity supply.
1.2 STATEMENT OF THE PROBLEM
Some places like Egal international airport uses a combined different electricity
sources intended to escape power cut offs that will malfunction the services
going on the airport .
The main problem that faces these sites is
 Power interruptions
If power interruption happens it may lose the data in computers or damage
electronics and electric machines. In the case of this interruption occurs it needs
a person that shifts the load source to another one, this involves a lot of human
efforts which is another challenge.
The commercial sites and industries uses database to do services and produce
items for their customers which means they can’t tolerate power cut offs
believed to effect the equipment and economy of the businesses and industries.
Our recommendation of Auto power supply control from four different sources
have the capability and strength to solve these challenges in the power supply
control into new technological ways with cost effective. It will excellently
increase the automation and efficiency of the system.
This system will automatically shift the load supply if one of the supplies fails
by going in to another active supply and also if the failed one becomes active
again it will immediately shift the load supply to the previous one.
2
.3 OBJECTIVE OF THE PROJECT
Our project will focus on constructing a control system of an integrated
renewable and other power sources to contribute a good electricity control
system.
The objectives of the project will be
 provide uninterrupted power supply
 increase the rate of interconnected power sources
 promote the use renewable energy technologies
 reduce the damage of customer’s equipment
 totally remove the role of human load shift operator
 increase the efficiency and reliability of the grid system
1.4 LIMITATION OF THE PROJECT
The limitation of our project are




Shortage of time
Lack of books
Some electrical components in the project can’t be found in the market
Lack of experience for preparing this proposal
1.5 ORGANIZATION OF DOCUMENTATION
In our project we start chapter one which contains motivation, problem
statement, objective of the project,and limitations of the project. In chapter two
we will talk about the definition of the project , circuit and block diagrams ,
advantages and disadvantages of the our project and the last application and
their scope.
In chapter three we will see calculations, software and hardware requirements,
material and components, the design and finally the implementation and testing.
The last chapter four will be conclusion and recommendation of the project.
3
CHAPTER TWO
LITERATURE REVIEW
2.1 Definitions
This auto power supply control system works on the principle of auto function for
switch over the load to other available source without wasting any time or switch off the
load. Here for the demonstration purposes we have used the selection keys for switch
off any source of supply. In this system, the microcontroller which is very essential
component of this system always, keep sensing the whole available sources.
When any source is switched off through the selection keys then the microcontroller
shifted the load to the other supply source by giving the signal to the relay driver IC
then the relay driver IC switched on the appropriate load relay. The whole function is
done by the microcontroller in micro seconds and this shifted time can be changed
during the programming of microcontroller.
Here 4 load relays are used which are connected in parallel with load and 4 sources of
supplies are also connected in parallel with these load relays. These load relays consist
of normally open and close contacts and are operated through the relay driver IC.
We have checked this system by connecting the lamp at output side as a load when any
interruption is take place during the shifted time then the lamp is blinking but here there
is no any blinking take place during the shifted time means there is no any interruption
in supplying the power at output side.
The project can be further enhanced by using other sources like wind power also and
then taking into consideration for using the possible whose tariff remains lowest.
Therefore, this project provides an effective solution to provide an alternative power
supply during frequent power cuts.
4
2.2 Diagrams
2.2.1 Circuit Diagram
The circuit diagram of a simple 100 watt inverter using IC CD4047 and
MOSFET IRF540.
CD4047 is low power CMOS a stable multi vibrator IC.
Here is wired as an a stable multi vbrator producing two pulse trains of 0.01s which
are 180 degree out of phase at the pins 10 and 11 of the IC.
Figure 1 wring diagram
5
2.2.2 Block Diagram
Here is the block diagram of the auto power supply control system from 4 different
sources using pic microcontroller with all the essential components. The Block
Diagram of the auto power supply control system from 4 different sources using pic
microcontroller:
Figure 2 Blocking diagram
6
2.3: Components
Transformer:In this auto power supply control system, the transformer is used for
connecting this system directly to the 220V ac. It steps down the 220V ac into 12V ac .it
consists of two windings and work on the principle of mutual induction.
Bridge rectifier:In this auto power supply control system, the bridge rectifier is used
for converting the 12V ac voltages into dc voltages for supplying the power to the other
electronics components.
Voltage Regulator:In this auto power supply control system, the voltage regulator is
used for regulating the 12V dc voltages into 5V dc voltages for supplying the power to
the LCD display, microcontroller and relay driver IC. In this system LM 7805 voltage
regulator is used for regulating the bridge rectifier the voltages.
LCD Display: In this auto power supply control system, the LCD display is used for
displaying thesource of supply on which the whole system or load has shifted. It also
displays the voltages which are coming from current source. It is interfaced with
microcontroller and powered up with 5V dc.
Selection Keys:In this auto power supply control system, the selection keys are the
basically push buttons which are used for checking the working function of this system.
These are pushed up one by one for demonstration purposes.
PIC Microcontroller 18F452: In this auto power supply control system, the Pic
18F452 microcontroller is used for the auto selection of the available source. It shifted
the load to the other power supply source automatically without any interruption. It is
programmed in C language with help of micro C software and is powered up with 5V dc
voltages. It is interfaced with LCD display and relay driver IC.
7
Relay Driver: In this auto power supply control system, the relay driver IC is used for
driving the load relays. This relay receives the signal from microcontroller for shifted
the load on another supply source. It is powered up with 5V dc and interfaced with
microcontroller.
Load:In this auto power supply control system, the lamp is used here as an output load
for demonstration purposes.
2.4 Working Principle

This project uses an arrangement of 4 different sources of supply which are
channelized to a load so as to have uninterrupted operation of the load.

As it is not practicable to get 4 sources of supply such as mains supply,
generator supply, inverter supply and solar supply we used one sources and set
of relays.

We have taken first source with mains supply and assumed as if being fed from
4 different source by connecting all the 4 incoming source in parallel

The ac source to the lamp is connected to four relays by making the entire
normal open contacts parallel and all the common contacts in parallel.

4 push button switches are used which represent failure of corresponding supply
respectively and are interfaced to the controller.

Initially we have given high input singles to the microcontroller, so as result the
controller generates a low output to active the first relay driver.

This will result in the relay being energized and the lamp glows.

While the push button for mains is pressed that represent failure of mains supply
as a result the supply is provide from the next source.

And the microcontroller receives high input and generates low output to active
the second relay driver.

This will result in the second relay being energized and the lamp glows.

When we press the generator button, it indicates the generator fails to operate
and the supply comes from the next source.
8

The next source will supply high input to the controller and which will provide
low signal to the third relay and the lamp switches on

When we press the third push button the supply will chose next source now the
fourth source will provide input to the microcontroller.

Controller activates the fourth relay and the load will get the supply and the
lamp continues to glow.

When all the relay are off leaving no supply to the lamp, the lamp is switched
off
2.5 Advantages
 Controlling Power supply from four different sources if any problem occurred in
one sources then the other sources can be used.
 This system is more compact and reliable as compared to the electrical ATS
panels.
 This system is less costly as compared to the other power control system.
 Simplicity of design.
 Fast transient response.
2.6 Disadvantages
 Switching noise and ripple exist
 My require a heat sink
2.7 Application
 This system could be used in that places where we have different sources of
supply such as solar, main and generator.
 This system could be used in industrial for supplying the uninterrupted power
supply to industrial machines.
9
 This system could be used in educational institutes and hospitals for supplying
the uninterruptable power supply to hospital or educational equipment.
 Banks are also other uses of this system.
 Hotel also need no break power.
 Commercial sites can’t tolerate power cut offs so it is a solution there.
2.8 Scope statement
The scope of our project is every place that uses four different sources of power
supply. This can be

Airports

Hospitals

Colleges or educational institutes

Industries

Commercial sites such as malls

Hotels

Government institutes
Auto power supply control system of four different sources can help these above places
to get reliable and uninterrupted power system. This will boost the effectiveness of
functions done by these above sites.
10
CHAPTER THREE
Analysis and Design
3.1Analysis
The site of the project is HargeisaGeneral Hospital, after many assessments on how
many power sources the hospital uses and also how they control these supplies, we
noticed that the hospital is a victim of power interruptions. As they use change over to
shift power supply from back-up generators to the government grid or Sompower grid.
Our project’s auto power supply control will offer the hospital a smooth uninterrupted
power supply. At the end of this chapter , to get four power sources for the hospital we
are recommending a standalone solar system capable to power the hospital.
3.1.1 Current Power supply sources of the hospital
Government utility grid
75 kw
Sompower grid
75 kw
Two backup generators
75 kw
Table 1 of power sources of the hospital (current)
3.2 Design
As we mentioned previous chapters , our project consist of electronic components such
as microcontroller, transformer, relays , LCD ,regulator , relay driver and etc. in this
chapter we consider the programming, hardware requirement and software requirement
of the project , its cost and implementation.
11
3.2.1 Programming
The full programe is in the appendix part of the but here it is a part of the programing
Figure 3 a part of the programming
3.2.2 Hardware requirement
List of components
Quantity
Cost
per Total cost per
component in USD
component
1. Resistor
11
$ 2.25
$ 24.75
2. Capacitor
5
$3
$15
3. Intergated Circuit
3
$ 17
$ 51
4. Microcontroller
1
$ 5.09
$ 5.09
$ 6.1
$ 6.1
PIC16F877A
5. Crystal
oscillator 1
4MHz
6. Voltage regulator
1
$ 1.95
$ 1.95
7. Relays
4
$ 4.16
$ 16.64
8. Transformer
1
$ 1.68
$ 1.68
9. 16*2 LCD
1
$7
$7
10. Plain PCB
1
$ 12.95
$ 12.95
12
Total
29 items
$ 142.16
Table 3 cost analysis of the Autopower supply control
3.3 Addition to a four power source to the Hargeisa general hospital
3.3.1 Solar power system
3.3.2 Overview
The total electrical power consumption of the Hospital is 75kw the Hospital gains
electricity from the utility of Sompower and Government utility . The cost energy is
very high one dollar per one unit which is 0.75$, also Hargeisa general hospital has two
backup generators which use 3000 litter per week as it costs 7800$ each month. The
Hargeisa general hospital will get cheap and reliable electricity that has not any power
interruption, so we are designing solar power system project in the Hospital.
3.3.3 A stand-alone Solar system
To be able to power the whole hospital independent when the other sources are off or
out , we are proposing a stand-alone solar system.
13
Figure 4 A simple stand-alone solar power system
3.4 Solar system components
In this project we prefer to use install polycrystalline type of solar panels.
These panel can withstand if it is partially covered so they are reliable.
The basic components of a Stand-alone PV system is








Solar photovoltaic modules
Array mounting racks
Grounding equipment
Combiner box
Surge protection (often part of the combiner box)
Inverter
Meters – system meter and kilowatt-hour meter
Disconnects:
 Array DC disconnect
 Inverter DC disconnect
 Inverter AC disconnect
 Exterior AC disconnects
 Battery bank
14
3.4.1 Solar photovoltaic modules
Photovoltaic modules use light energy (photons) from the Sun to generate electricity
through the photovoltaic effect. The majority of modules use wafer-based crystalline
silicon cells or thin-film cells. The structural (load carrying) member of a module can
either be the top layer or the back layer. Cells must also be protected from mechanical
damage and moisture. Most modules are rigid, but semi-flexible ones based on thin-film
cells are also available. The cells must be connected electrically in series, one to
another.
Figure1 Solar photovoltaic modules
3.4.2 Array mounting racks
Arrays are most commonly mounted on roofs or on steel poles set in concrete. In certain
applications, they may be mounted at ground level or on building walls.
In our project we are using ground mount solar installation method.
Figure: 2 Ground mount solar installation
3.4.3 Combiner Box
15
Wires from individual PV modules or strings are run to the combiner box, typically
located on the control room. These wires may be single conductor pigtails with
connectors that are pre-wired onto the PV modules. The output of the combiner box is
one larger two wire conductor in conduit. A combiner box typically includes a safety
fuse or breaker for each string and may include a surge protector.
3.4.4 Surge protection
Surge protectors help to protect your system from power surges that may occur if the
PV system or nearby power lines are struck by lightning. A power surge is an increase
in voltage significantly above the design voltage.
3.4.5 Inverter
Inverters take care of four basic tasks of power conditioning:
• Converting the DC power coming from the PV modules or battery bank to AC power
• Ensuring that the frequency of the AC cycles is 60 cycles per second
• Reducing voltage fluctuations
• Ensuring that the shape of the AC wave is appropriate for the application, i.e. a pure
sine wave for hybrid-connected systems
3.4.6 Meters – system meter and kilowatt-hour meter
Essentially two types of meters are used in PV systems:
• Utility Kilowatt-hour Meter
• System Meter
Utility Kilowatt-Hour Meter– The utility kilowatt-hour meter measures energy
delivered to or from the grid. On homes with solar electric systems, utilities typically
install bidirectional meters with a digital display that keeps separate track of energy in
both directions. Some utilities will allow you to use a conventional meter that can spin
in reverse. In this case, the utility meter spins forward when you are drawing electricity
from the grid and backwards when your system is feeding or “pushing” electricity onto
the grid.
System Meter– The system meter measures and displays system performance and
status.
16
Monitored points may include power production by modules, electricity used, and
battery charge. It is possible to operate a system without a system meter, though meters
are strongly recommended. Modern charge controllers incorporate system monitoring
functions and so a separate system meter may not be necessary.
3.4.7 Grounding equipment
Grounding equipment provides a well-defined, low-resistance path from your system to
the ground to protect your system from current surges from lightning strikes or
equipment malfunctions. Grounding also stabilizes voltages and provides a common
reference point. The grounding harness is usually located on the roof.
3.4.8Disconnects
Automatic and manual safety disconnects protect the wiring and components from
power surges and other equipment malfunctions. They also ensure the system can be
safely shut down and system components can be removed for maintenance and repair.
For grid connected systems, safety disconnects ensure that the generating equipment is
isolated from the grid, which is important for the safety of utility personnel. In general,
a disconnection is needed for each source of power or energy storage device in the
system. For each of the functions listed below, it is not always necessary to provide a
separate disconnect
Array DC Disconnect – The array DC disconnect, also called the PV disconnect, is
used to safely interrupt the flow of electricity from the PV array for maintenance or
troubleshooting. The array DC disconnects may also have integrated circuit breakers or
fuses to protect against power surges.
Inverter DC Disconnect – Along with the inverter AC disconnect, the inverter DC
disconnect is used to safely disconnect the inverter from the rest of the system. In many
cases, the inverter DC disconnects will also serve as the array DC disconnects.
Inverter AC Disconnect – The inverter AC disconnects the PV system from both the
building’s electrical wiring and the grid. Frequently, the AC disconnect is installed
inside the building’s main electrical panel. However, if the inverter is not located near
the electrical panel, an additional AC disconnect should be installed near the inverter.
17
Exterior AC Disconnect – Utilities commonly require an exterior AC disconnect that is
lockable, has visible blades and is mounted next to the utility meter so that it is
accessible to utility personnel. An AC disconnects located inside the electrical panel or
integral to the inverter would not satisfy these requirements. One alternative that is as
acceptable to some utilities as an accessible AC disconnect is the removal of the meter
itself, but this is not the norm. Prior to purchasing equipment, consult the electric utility
to determine their requirements for interconnection.
3.4.9 Battery Bank
Batteries store direct current electrical energy for later use. This energy storage comes at
a cost, however, since batteries reduce the efficiency and output of the PV system,
typically by about 10 percent for lead-acid batteries. Batteries also increase the
complexity and cost of the system.
3.5 Solar system sizing
Daily demand of the hospital is 75 kw . On the other hand, the hours between 8:00 am
upto 1:00 pm is used the most power.
Daily demand
6×20 kw= 120 Kwh
6×30 kw=180 kwh
7×5kw=35 kwh
Total = 335 kwh
PV sizing
daily power demand
peak load ×1.3= 98 kw
The system will powere the hospital 60% directly while the rest 40% will be stored in
the battery bank.
Energy Storage = 335 kwh +40% of 335 kw
18
= 335 kwh + 134 kwh
= 469 Kwh
= 40% of 335 kwh÷ 60% = 223 kwh
= 223 kwh + 335 kwh= 558 kwh+5%
storage loss
= 558 kwh ×1.05= 586 kwh
Energy storage= 363 kwh
Solar PV for storage= 363 kwh÷6 hrs= 55.846 kw × 1.2 = 67 kw
Number of solar panels to solar inverters= PV generator ÷ PV rating=
98000÷300W/panel= 327 pieces
Inverter = 75 kw × 1.3= 100 kw
Number of inverters = 100 kw ÷ 20 kw/inverter = 5 inverters
Battery [ lithium ion] = 58 v × 68 k Ah = 3.944 kwh = 4 kwh
Number of battery = Energy storage ÷ energy / battery = 363 kwh ÷ 4 kwh = 90 pieces
Battery inverter = 100 kw
Solar panels of the battery = 67 kw ÷ 300w/ panel= 224 pieces
Total solar pv panels = 327 + 223 = 550 pieces
Area/ panel = 2m2
Total area = 550 pcs × 2m2 + 20%( for spacing)
= 1100 m2 + 220 m2 = 1,320 m2
550 panels ÷ 5 inverters= 110 panel/ inverter
110/ 18 panel/inverter = 6 string( series)
= 6 parallel
19
18 × 36.8 v = 662 v – inverter rating voltage
3 phase
Panels
20
kw
20 Kw
inverter
Battery connections = 558/ battery
11 series battery = 11 × 58 v = 638 v
90 battery ÷ 11 series battery = 8 parallel string batteries
400 v
100 kw
Battery bank
Inverter
600 v
20
400v
3.6 Solar system cost estimation
The following table will be presented the overall initial cost of the proposed solar
system.
Hardware
requirement
specifications Quantity
Unit cost
Total cost
Solar PV
300 W
550
$ 220
$ 121,000
Solar inverter
( SMA)
Battery inverter
20KW
5
$ 5000
$ 25,000
100 KW
1
$ 18,000
$ 18,000
Cables
Lumsun
1
$ 2,000
$ 2,000
CB
Lumsun
1
$ 500
$ 500
Battery
Lithium ion
90
$ 900
$ 81,000
Solar frame ground
And
mounting
structures
Transportation
550
$ 45
$ 24,750
1
$ 4000
$ 4,000
Installation
1
$ 10,000
$ 10,000
Accessories
1
$ 1000
$ 1,000
Total
$ 287,250
Table 4 cost estimation of the proposed solar system to the hargeisa
general hospital.
21
CHAPTER FOUR
CONCLUSION
This project of AUTOMATIC POWER SUPPLY FROM FOUR
DIFFERENT SOURCES: Solar, Inverter, Main and Generator” USING A
MICROCONTROLLER is used to handle power supply from Solar, Inverter,
Main and Generator” automatically using microcontroller concept. The
significance of this project lies in its various advantages and wide places of
applications such as Industries, Hospitals, Banks; it has been developed by
integrating Colleges/Schools, etc. It has been developed by integrating features
of all the hardware components used. Presence of every module has been
reasoned out and placed carefully thus contributing to the best working of the
unit.
This project provides 75KW stand-alone solar power system which is a
practical solution to provide an alternative power supply or uninterrupted
power supply in automated mode to the load during frequent power cuts or in
cases where power cuts or power outages cannot be avoided.
Now the hospital
uses electricity from the Grid and diesel generator to
generate electricity needed in special cases and as commonly known fossil
fuels are the most expensive sources to generate electricity, costs more money
and pollutes the environment, so in order to overcome these problems this
project proposes stand-alone solar system with generator backup to be installed
for the hospital, apart from their high initial investments, solar systems require
less operation and maintenance costs, the system will last long and save
money.
22
REFERENCES
[1] Robert Dowuona-Owoo (2008), “Design and construction of three phase automatic transfer
switch.” A thesis presented at regent university college of science and technology Ghana.
PP100-120
[2] L S Ezema, B U Peter, O O Haris, “DESIGN OF AUTOMATIC CHANGE OVER SWITCH WITH
GENERATOR CONTROL MECHANISM”, ISSN: 2223-9944, vol 3, No 3, November 2003. PP 230287
[3] Jonathan (2007), “Manually Controlled Changeover System.” Vol.2, No.5. November, 2011.
PP 152 – 180
[4] Mbaocha C. (2012), “Smart Phase Changeover Switch using AT89C52 Microcontroller.”
Journal of Electrical and Electronics Engineering vol.1; Issue 3: PP 31-44
[5] Katz R and Boriella G (2005), “Contemporary Logic Design. 2nd edition.” Prentice Hall,
Italy. PP 445-589
[6] Shanmukha Nagaraj and Ramesh S (2013), “Programmable Logic Controlled Circuits.”
International Journal of Research in Engineering and Technology Vol.1, issue 2, July 2013; PP
111-116.
[7] L.S. Ezema, B.U. Peter, O.O. Harris (2012), “Design of Automatic Change Over Switch
with Generator Control Mechanism.” Electrical Power and Electronic Development
Department, Projects Development Institute (PRODA), Enugu: Natural and Applied Science,
Vol.3, No.3. November, 2012. PP 125 – 130.
[8] Charlie Hume, (effective march 2015), “Transfer switch 101: an introductory guide to
picking the right transfer switch for your environment, White paper WP140001EN.” Retrieved
from:
www.eaton.com/ecm/group/public/@pub/@electrical/documents/.../wp140001en.pdf.
23
Appendix A
Table 3 a cost analysis of Auto power supply control
List of components
Quantity
Cost
per Total cost per
component in USD
component
1. Resistor
11
$ 2.25
$ 24.75
2. Capacitor
5
$3
$15
3. Intergated Circuit
3
$ 17
$ 51
4. Microcontroller
1
$ 5.09
$ 5.09
$ 6.1
$ 6.1
PIC16F877A
5. Crystal
oscillator 1
4MHz
6. Voltage regulator
1
$ 1.95
$ 1.95
7. Relays
4
$ 4.16
$ 16.64
8. Transformer
1
$ 1.68
$ 1.68
9. 16*2 LCD
1
$7
$7
10. Plain PCB
1
$ 12.95
$ 12.95
Total
29 items
$ 142.16
24
Table 4 the cost estimation of the proposed Solar system to Hargeisa
general hospital.
Hardware
requirement
specifications Quantity
Unit cost
Total cost
Solar PV
300 W
550
$ 220
$ 121,000
Solar inverter
( SMA)
Battery inverter
20KW
5
$ 5000
$ 25,000
100 KW
1
$ 18,000
$ 18,000
Cables
Lumsun
1
$ 2,000
$ 2,000
CB
Lumsun
1
$ 500
$ 500
Battery
Lithium ion
90
$ 900
$ 81,000
Solar frame ground
And
mounting
structures
Transportation
550
$ 45
$ 24,750
1
$ 4000
$ 4,000
Installation
1
$ 10,000
$ 10,000
Accessories
1
$ 1000
$ 1,000
Total
$ 287,250
25
Appendix B
Codes Written for the MCU in Assembly Language
;=========================================================
;=========================================================
; UNINTERRUPTED POWER SUPPLY
;==========================================================
;==========================================================
; DEFINATIONS
;==========================================================
;==========================================================
;REGISTERS
Ctr Equ 02h
;BIT MEMORY
ADCReg Equ 20h
PPReg Equ 21h
;PORT
ADCPort Equ P1
PPort Equ P3
;BIT
ADCReg0 Equ 00h
ADCReg1 Equ 01h
ADCReg2 Equ 02h
ADCReg3 Equ 03h
ADCReg4 Equ 04h
ADCReg5 Equ 05h
ADCReg6 Equ 06h
ADCReg7 Equ 07h
PPReg0 Equ 08h
Charger Equ P3.7
Mains Equ P1.0
;=========================================================
;=========================================================
; VECTOR ADDRESSES
;=========================================================
;=========================================================
;=========================================================
Org 0000h ;RESET VECTOR ADDRESS
ljmp Start ;Jump to start of program
;=========================================================
Org 0003h ;EXTERNAL INTERRUPT0 VECTOR ADDRESS
reti ;Return from Interrupt
;=========================================================
Org 0Bh ;TIMER0 INTERRUPT VECTOR ADDRESS
acall Timer
reti
;=========================================================
Org 13h ;EXTERNAL INTERRUPT1 VECTOR ADDRESS
reti
;=========================================================
Org 1Bh ;TIMER1 INTERRUPT VECTOR ADDRESS
reti
;=========================================================
Org 23h ;SERIAL INTERRUPT VECTOR ADDRESS
reti ;Not used
;=========================================================
Org 30h ;Program starts here
26
Start:
mov SP,#40h ;Stack Pionter intialized
19
clr RS0 ;Bank0 selected
clr RS1
mov PPort,#255
mov ADCPort,#255;Initialising ADCPort as input port
setb Mains
mov Ctr,#8
mov TMOD,#17 ;Timer0 (16bit Timers)
mov TH0,#11 ;Timer0 reload value= 55535
mov TL0,#219
setb ET0 ;Timer0 Interrupt enabled
setb TR0 ;Start Timer0
setb EA ;Global interrupt enabled
jmp $ ;Wait
;=========================================================
Timer:
clr TR0 ;Stop Timer0
mov TH0,#11 ;Timer0 reload value= 3035
mov TL0,#219
setb TR0 ;Start Timer0
djnz Ctr, EndTimer
mov Ctr,#8
mov ADCReg,ADCPort
setb ADCReg0
acall ADConversion
acall ChargeBattery
acall UpdatePPort
EndTimer:
ret
;=========================================================
ADConversion:
mov dptr,#PPData
mov A,ADCReg
movc A,@A+dptr
mov PPReg,A
ret
;=========================================================
ChargeBattery:
mov A,ADCReg
cjne A, #10,ChargeBat
cjne A, #12,StopCharging
ret
ChargeBat:
clr Charger
ret
StopCharging:
setb Charger
ret
;=========================================================
UpdatePPort:
jb Mains,lMains
clr PPReg0
mov C,Charger
mov PPort,PPReg
mov Charger,C
ret
lMains:
mov C,Charger
mov PPort,#255
27
mov Charger,C
20
ret
;=========================================================
;=========================================================
PPData: db 243,243,243,243,243
db 242,242,242,242,242
db 241,241,241,241,241
db 240,240,240,240,240
db 239,239,239,239,239
db 238,238,238,238,238
db 237,237,237,237,237
db 236,236,236,236,236
db 235,235,235,235,235
db 234,234,234,234,234
db 233,233,233,233,233
db 232,232,232,232,232
db 231,231,231,231,231
db 230,230,230,230,230
db 229,229,229,229,229
db 228,228,228,228,228
db 227,227,227,227,227
db 226,226,226,226,226
db 225,225,225,225,225
db 224,224,224,224,224
db 223,223,223,223,223
db 222,222,222,222,222
db 221,221,221,221,221
db 220,220,220,220,220
db 219,219,219,219,219
db 218,218,218,218,218
db 217,217,217,217,217
db 216,216,216,216,216
db 215,215,215,215,215
db 214,214,214,214,214
db 213,213,213,213,213
db 212,212,212,212,212
db 211,211,211,211,211
db 210,210,210,210,210
db 209,209,209,209,209
db 208,208,208,208,208
db 207,207,207,207,207
db 206,206,206,206,206
db 205,205,205,205,205
db 204,204,204,204,204
db 203,203,203,203,203
db 202,202,202,202,202
db 201,201,201,201,201
db 200,200,200,200,200
db 199,199,199,199,199
db 198,198,198,198,199
db 197,197,197,197,197
db 196,196,196,196,196
db 195,195,195,195,195
db 194,194,194,194,194
db 193,193,193,193,193
;=========================================================
;=========================================================
28
End
29