DEPARTMENT OF ELECTRICAL ENGINEERING
BACHELOR OF ENGINEERING
NTA LEVEL 8
SENIOR PROJECT TWO
PROJECT TITLE:
DESIGN OF SOLAR-WIND HYBRID POWER FOR
KISASIDA DRIP IRRIGATION SCHEME
PROJECT TYPE:
DESIGNING
STUDENT’S NAME:
IDD, ALLY
ADMISSION NO:
100302G8383
SUPERVISOR:
DR. A. KILIMO
YEAR OF STUDY:
2013/2014
May, 2014
i
DECLARATION
I, ALLY IDD, a student of Dar es salaam Institute of Technology (DIT), in Electrical
Engineering Department, with registration number 100302G8383.Bachelor of Engineering
Hereby declaring that all the work described in this report is my own, except where explicitly
indicated otherwise.
Wherever information from other sources is included, I reference material source is also given.
Signature…………...
Signature……...........
Date:……………….
Date:……………….
ALLY IDD
Dr. A. Kilimo
ii
ABSTRACT
Kisasida Irrigation Scheme is the project established by Singida Municipal Council since 2012. It
is located 16 Kilometers from Singida town along Arusha road. The total area of the Kisasida
Village is 150 acres where the scheme designed for irrigation is 32 acres. Initially an
underground well was drilled and temporary diesel pump for pumping water from the well to the
overhead tank was installed. Due to daily increase of fuel and maintenance costs of the diesel
pump, the scheme is running at a very high cost.
The aim of this project is to design a solar wind hybrid power that can be used at Kisasida
Irrigation Scheme.
iii
ACKNOWLEDGEMENTS
First of all, I am so grateful to Almighty God, the Creator for giving health and enabling me to
do this project.
With high respect, I would like to express my sincere gratitude to all Electrical Department Staff
for their support and encouragement.
My special thanks go to Dr. A.Kilimo, the project coordinator and my supervisor for his
constructive advice and guidance which had been valuable during the preparation of this project.
It is difficult to acknowledge everyone who in one way or another assisted me during preparation
of my project. Therefore I would like to give my general thanks to all who supplied me with
necessary information and assistance toward my project.
iv
Table of Contents
DECLARATION ......................................................................................................................... i
ABSTRACT ............................................................................................................................... iii
ACKNOWLEDGEMENTS ....................................................................................................... iv
List of figures ............................................................................................................................... viii
List of Table ................................................................................................................................... ix
ABBREVIATIONS ........................................................................................................................ x
CHAPTER ONE ............................................................................................................................. 1
BACKGROUND INFORMATION ............................................................................................... 1
1.0 INTRODUCTION ................................................................................................................. 1
1.2 PROBLEM STATEMENT ................................................................................................... 1
1.2.1 Main Objectives .............................................................................................................. 1
1.2.2 Specific Objectives ......................................................................................................... 1
1.3 Significance of the project..................................................................................................... 2
1.4 Methodology ......................................................................................................................... 2
CHAPTER TWO ............................................................................................................................ 3
LITERATURE REVIEW ............................................................................................................... 3
2.1INTRODUCTION .................................................................................................................. 3
2.2 Existing System ..................................................................................................................... 3
2.3 Proposed System ................................................................................................................... 4
2.4 Irrigation ................................................................................................................................ 4
2.4.2 Terraced Irrigation .......................................................................................................... 5
2.4.3 Sprinkler System............................................................................................................. 5
2.4.4 Rotary Systems ............................................................................................................... 5
2.4.5 Drip Irrigation ................................................................................................................. 5
2.5 Water Pumping...................................................................................................................... 6
2.5.1 Submersible Pumps ........................................................................................................ 6
2.5.2 Centrifugal Pumps .......................................................................................................... 7
2.6 Energy Sources ...................................................................................................................... 7
2.6.1 Non-Renewable Energy.................................................................................................. 7
2.6.2 Renewable Energy .......................................................................................................... 7
v
2.6.3 Advantages of Renewable Energy.................................................................................. 8
2.4.4 Disadvantages of Renewable Energy ............................................................................. 8
2.7 Hybrid Power System ........................................................................................................... 8
2.7.1 Solar-generated Electricity – Photovoltaic ..................................................................... 9
2.7.2 Wind Energy ................................................................................................................. 14
CHAPTER THREE ...................................................................................................................... 17
3.0 Data Collection .................................................................................................................... 17
3.1FIELD DATA ...................................................................................................................... 17
3.1.1 Data Collected From Site ............................................................................................. 17
3.1.2 Metrological Data ......................................................................................................... 17
3.1.3 Vegetable Spacing And Water Requirement Per Day .................................................. 18
3.2 TECHNICAL DATA .......................................................................................................... 18
3.2.1 Estimated Load Demand for the Houses around the Scheme ...................................... 18
3.2.2 Available Solar Modules in the Market ........................................................................ 18
3.2.3 Wind Turbine Available In the Market ........................................................................ 20
3.2.4 Specification for Solar Charge Controllers .................................................................. 21
3.2.5 Specifications for Inverter ............................................................................................ 21
3.2.6 Specifications for Wind Turbine Controller ................................................................. 23
CHAPTER FOUR ......................................................................................................................... 24
DATA ANALYSIS ....................................................................................................................... 24
INTRODUCTION ........................................................................................................................ 24
4.1 CALCULATING THE AMOUNT OF POWER REQUIRED BY PUMP ........................ 24
4.1.1 Determination of Total Volume of Water Required Daily ........................................... 24
4.1.2 Determination of Flow Rate ......................................................................................... 25
4.1.3 Determination of Rating of the Pump........................................................................... 26
4.1.4 Block Diagram of the Proposed Solar-Wind Hybrid Power System............................ 28
4.1.5 Circuit Diagram of the Proposed System ..................................................................... 28
4.2 ANALYSIS ON POWER TO DESIGNED ........................................................................ 28
4.3 SOLAR PV SYSTEM DESIGN ......................................................................................... 29
4.3.1. Determine power consumption demands .................................................................... 29
4.3.2. Size the PV modules .................................................................................................... 30
vi
4.4 WIND POWER SYSTEM DESIGN .................................................................................. 33
4.4.1 Calculating the size of wind turbine ............................................................................. 35
4.4.2 Number of turbines required......................................................................................... 36
4.4.3
Graph of the average output power generated by the wind turbine. ....................... 36
4.5 CONDUCTOR SIZING ...................................................................................................... 39
4.5.1 Cable sizing from pv module to Solar charge controller .............................................. 39
4.5.2 Cable sizing from wind turbine to Wind turbine controller ......................................... 39
4.5.3 Cable sizing from Solar turbine controller to the busbar.............................................. 40
4.5.4 Cable sizing from busbar to inverter ............................................................................ 40
4.5.5 Cable sizing from Wind turbine controller to busbar ................................................... 40
4.5.6 Busbar sizing ................................................................................................................ 40
4.6 INSTALLATIONS.............................................................................................................. 41
4.7 COST ESTIMATION ......................................................................................................... 41
CONCLUSION ............................................................................................................................. 42
RECOMMENDATIONS .............................................................................................................. 42
References ..................................................................................................................................... 43
APPENDIX ................................................................................................................................... 44
Appendix 1 WORK SCHEDULE ............................................................................................. 44
Appendix 2 Examples of wiring systems and reference methods of installations .................... 45
Appendix 3 Load Distribution Factors ...................................................................................... 52
vii
List of figures
Figure 2.1 Block diagram of existing system………………………………………………….….4
Figure 2.2 Bock diagram of the proposed system……………………………………………....…5
Figure 2.3 Typical Drip Layout System…………………………………………………………..7
Figure 2.4 Block diagram of solar-wind hybrid power system……………………………….…10
Figure 2.5 Principle of operation of Solar cell…………………………………………….……..11
Figure 2.6 Photovoltaic System………………………………………………………………….12
Figure 2.7 Monocrystalline solar panel………………………………………….………...…….13
Figure 2.8 Polycrystalline solar panel……………………………………………………….…...13
Figure 2.9 Amorphous Silicon „Thin Film Solar Panel‟…………………….…………….….….14
Figure 2.10 Block diagram for conversion of wind energy to electrical energy……….………..17
Figure 4.1 Block diagram of the proposed Solar-Wind Hybrid Power System……….….……...28
Figure 4.2 Circuit diagram of the complete power system…………………………..…………..28
Figure 4.3 A Graph of Power Generated by a single Turbine…………………………..……….39
viii
List of Table
Table 3.1 Average wind speed (m/s) in Singida Region ……………………………………….17
Table 3.2 Average solar radiation in (kWh/m2/day)……………………………………………17
Table 3.3Vegetable spacing and water requirement per day.......................................................18
Table 3.4 Estimated Load Demand……………………………………………………………..18
Table 3.5 below shows solar panels available in the market…………………………………...19
Table 3.6 Wind Turbine Specification………………………………………………………….20
Table 3.7 Solar charge controller specifications………………………………………………..21
Table 3.8 Table for Inverter specifications……………………………………………………..22
Table 3.9 Wind Turbine controller specifications……………………………………………….23
Table 4.1 Table of power generated by a single turbine at 20m tower height………………….38
ix
ABBREVIATIONS
AC
BC
Alternating Current
Battery Capacity
BIPV
Build Integral Photovoltaic
CdTe
Cadmium Telluride
CIS
Copper Indium Diselinide
CO2
Carbon dioxide
D.C
Direct Current
ICT
Information and Communication Technology
IEC
International Electrotechnical Commission
MCB
Miniature Circuit Breaker
PV
Photovoltaic
TMA
Tanzania Metrological Agency
Vbatt
Battery
WECS
Wind Energy Conversion System
x
CHAPTER ONE
BACKGROUND INFORMATION
1.0 INTRODUCTION
Kisasida Irrigation Scheme is the project established by Singida Municipal Council since 2012. It
is located 16 Kilometers from Singida town along Arusha road. The total area of the Kisasida
Village is 150 acres where the scheme designed for irrigation is 32 acres. Singida Municipal
Council funded the initial stages of the project implementation with Tsh. 700 millions. Initially
an underground well was drilled and temporary diesel pump for pumping water from the well to
the overhead tank was installed.
After the completion of the project, it villagers will assume its ownership. The project aims at
poverty reduction through cultivation of vegetables such as tomatoes, onions and others.
1.2 PROBLEM STATEMENT
Kisasida irrigation scheme was designed to be manually operated drip irrigation where by the
irrigation process takes place by fetching water from the trenches using watering can. Trenches
receives water through pipes connected to the temporary storage tanks through water valve. The
storage tank of the scheme stores water that is pumped from underground well by using diesel
pump. Due to daily increase of fuel and maintenance costs of the diesel pump, the scheme is
running at a very high cost.
Hence the system needs very high investment on fuel consumption and maintenance costs of the
diesel pump.
1.2.1 Main Objectives
The main objective of this project is to design an alternative source of power for the pumping
system using renewable energy that can be used at Kisasida Irrigation Scheme.
1.2.2 Specific Objectives
•
Design a Solar-Wind Hybrid power.
•
To determine amount of water needed for irrigation daily.
•
To determine the rating of the pump to be used.
1
•
To supply power to the houses around the scheme.
•
To build a prototype.
1.3 Significance of the project
•
If the project will be implemented it will reduce the costs of pumping water by generating
hybrid power from solar and wind.
•
It will encourage farmers to increase production level by increasing cultivation area.
•
It will raise the income of the farmers as well as National income.
•
It will ensure food security for the whole year.
1.4 Methodology
Literature review
Data collection
Data analysis
Design of the system
Prototype building
Testing a prototype
Report writing
2
CHAPTER TWO
LITERATURE REVIEW
2.1INTRODUCTION
This chapter will focus on describing different systems of irrigation that have been adopted. Also
it will indicate how renewable energies are important in many aspects including agriculture field.
It will show how solar and wind power can be combined together to generate sufficient power
for pumping water from the well to the overhead tank(s).
2.2 Existing System
Currently farmers at Kisasida irrigation Scheme perform the irrigation activities traditional
methods. They use surface irrigation by fetching water from the trenches to the farm by using
irrigating can and buckets. The trenches receive water from the well by using diesel pump. The
current situation is highly in need of manpower, much time consumption and high cost of
running diesel generator which results into low productivity. This irrigation scheme suffers from
many difficulties, including poor water management.
Figure 2.1 Block diagram of existing system
3
2.3 Proposed System
The problems from the existing system can be avoided by establishing a system which can
manage water, that is, to supply water to the plant roots at required quantity and at reasonable
time. The proposed system could be affordable by introducing drip irrigation where water or
fertilizer will be poured to the root of the plant. Water will be pumped from the well to the
storage tank by using solar-wind hybrid powered pump instead of using diesel pump which is
very costful.
Hybrid Power
from Solar
modules and
wind turbine
Storage
Tank
Pump
Underground
Well
Farm
Fig 2.2: Block diagram of the proposed system
2.4 Irrigation
Irrigation is the artificial application of water to the soil usually for assisting in growing crops.
In crop production it is mainly used in dry areas and in periods of rainfall shortfalls, but also to
protect plants against frost. [1]
Agriculture is one of the fields where water is required in tremendous quantity. Wastage of water
is major problem in agriculture. Every time excess of water is given to the fields. There are many
techniques to save or to control wastage of water from agriculture. [2]
2.4.1 Ditch Irrigation
Ditch Irrigation is a rather traditional method, where ditches are dug out and seedlings are
planted in rows. Siphon tubes are used to move the water from the main ditch to the canals.
4
2.4.2 Terraced Irrigation
This is a very labor-intensive method of irrigation where the land is cut into steps and supported
by retaining walls. The flat areas are used for planting and the idea is that the water flows down
each step watering each plot. This allows steep land to be used for planting crops.
2.4.3 Sprinkler System
This is an irrigation system based on overhead sprinklers, sprays or guns, installed on permanent
risers. You can also have the system buried underground and the sprinklers rise up when water
pressure rises, which is a popular irrigation system for use on golf courses and parks.
2.4.4 Rotary Systems
This method of irrigation is best suited for larger areas, for the sprinklers can reach distances of
up to 100 feet. The word “Rotary” is indicative of the mechanical driven sprinklers moving in a
circular motion, hence reaching greater distances. This system waters a larger area with small
amounts of water over a long period of time.
2.4.5 Drip Irrigation
Drip irrigation also known as trickle irrigation or micro irrigation is an irrigation method which
minimizes the use of water and fertilizer by allowing water to drip slowly to the roots of plants,
either onto the soil surface or directly onto the root zone, through a network of valves, pipes,
tubing, and emitters. Drip irrigation is the targeted, intelligent application of water, fertilizer, and
chemicals that when used properly can provide great benefits such as; [3]
Increased Revenue from Increased Yields
Increased Revenue from Increased Quality
Decreased Water Costs
Decreased Labor Costs
Decreased Energy Costs
Decreased Fertilizer Costs
Decreased Pesticide Costs
Improved Environmental Quality
5
Figure 2.3: Typical Drip Layout System
2.5 Water Pumping
Pump can be defined as a mechanical device used to transfer liquid of various types. It converts
the energy provided by a prime mover, such as an electric motor, steam turbine, or gasoline
engine, to energy within the liquid being pumped.
There are many pump classifications. One classification is according to the method energy is
imparted to the liquid: kinetic energy, or positive displacement.
2.5.1 Submersible Pumps
Submersible pump (Electrical Submersible Pump) is centrifugal type of pump which pumps out
water from the bored hole or well. The pump is coupled with an electric motor. The shape of the
pump and motor is cylindrical which makes it easy to be fitted in drilled bore in the earth. The
pump remains dipped in water due to which there will not be any suction trouble. Submersible
pump is used for continuous discharge of water in quantity as well as for high heads. Most
submersible pumps must be installed in a special sleeve if they are not installed in a well, and
sometime they need a sleeve even if they are installed in a well. The sleeve forces water coming
into the pump to flow over the surface of pump motor to keep the motor cool. Without the sleeve
the pump will burn. The power cable is very important to be protected from accidental damage.
6
Advantage of submersible water pump compared to ordinary pumps is that, the submersible
pumps are more efficient as it pumps liquid which is close to the pump. It therefore functions
less than ordinary pumps. As these pumps are placed inside the sumps, it can detect the level of
water quite easily.
2.5.2 Centrifugal Pumps
Most of the irrigation pumps are in the category of centrifugal-type. A centrifugal pump uses an
“impeller” (like propeller) to spin water rapidly in a “casing”, “chamber”, or housing. This
spinning action moves the water through the pump by the means of centrifugal force.[4]
Centrifugal pumps may be “multistage” which means that they have more than one impeller and
casing, and the water is passed from one impeller to another with an increase in pressure
occurring each time. Each impeller/casing combination is referred to as a “stage”. All centrifugal
pumps must have a “wet inlet”, that is, there must be in both the inlet and the casing when the
pump is stated. They cannot suck water up into inlet pipe. They must be “primed” by adding
water to the intake (inlet) pipe and the case before the first use. To prime them you simply fill the
intake pipe with water and then quickly turn ON the pump. To put it simply, this type of pump
cannot suck air, only water, so if there is no water already in the pump it will not pull any water
up into it. Once it gets wet in it the first time, most centrifugal are designed to hold water with a
small valve so the pump does not need to be primed again every time you turn ON.
2.6 Energy Sources
Energy sources are of two types, Non-renewable energy sources and Renewable energy sources
2.6.1 Non-Renewable Energy
Is the type of energy that cannot be replenished (made again) in a short period of time, these are
like oil and petroleum products (including gasoline, diesel fuels and propane), natural gas, coal
and uranium (nuclear energy).
2.6.2 Renewable Energy
Is the energy that is generated from natural processes that are continuously replenished. This
includes sunlight, geothermal heat, wind, tides, water, and various forms of biomass. This
energy cannot be exhausted and is constantly renewed.
7
2.6.3 Advantages of Renewable Energy
Renewable energy produces little or no waste products such as carbon dioxide or
other chemical pollutants, so has minimal impact on the environment.
The major advantage with the use of renewable energy is that as it is renewable it
is therefore sustainable and so will never run out.
Renewable energy facilities generally require less maintenance than traditional
generators. Their fuel being derived from natural and available resources reduces
the costs of operation.
2.4.4 Disadvantages of Renewable Energy
It is difficult to generate the quantities of electricity that are as large as those
produced by traditional fossil fuel generators. This may mean that we need to
reduce the amount of energy we use or simply build more energy facilities. It also
indicates that the best solution to our energy problems may be to have a balance
of many different power sources.
Skilled and experienced hands are required to build the plant.
2.7 Hybrid Power System
A hybrid renewable energy system is a system in which two or more supplies from different
renewable energy sources (solar-thermal, solar-photovoltaic, wind, biomass, hydropower, etc.)
are integrated to supply electricity or heat, or both, to the same demand. The most frequently
used hybrid system is the hybrid which consists of Photovoltaic (PV) modules and wind turbines.
Combining renewable hybrid system with batteries as a storage system, to increase duration of
energy autonomy, will make optimal use of the available renewable energy resource and this in
turn can guarantee high supply reliability.
The main benefits (advantages) of a hybrid system can be summarized as: [5]
The possibility to combine two or more renewable energy sources, based on the natural
local potential of the users.
Environmental protection especially in terms of CO2 emissions reduction.
Low cost – wind energy, and also solar energy can be competitive with nuclear, coal and
gas especially considering possible future cost trends for fossil and nuclear energy.
Diversity and security of supply.
8
Fuel is abundant, free and inexhaustible.
Costs are predictable and not influenced by fuel price fluctuations although fluctuations
in the price of batteries will be an influence where these are incorporated.
The figure below shows a block diagram of solar and wind hybrid power
AC Load
Wind
generator
Wind Charge
Controller
Battery
Inverter
Solar Charge
controller
Bank
PV array
DC loads
Figure 2.4 Block diagram of solar-wind hybrid power system
2.7.1 Solar-generated Electricity – Photovoltaic
The Solar-generated electricity is called Photovoltaic (or PV). Photo-voltaic are solar cells that
convert sunlight to D.C electricity. These solar cells in PV module are made from semiconductor
materials. When light energy strikes the cell, electrons are emitted. The electrical conductor
attached to the positive and negative scales of the material allow the electrons to be captured in
the form of a D.C current. The generated electricity can be used to power a load or can be stored
in a battery. The figure 2.5 bellow shows the basic operation of solar cell.
Photovoltaic system is classified into two major types: the off-grid (stand alone) systems and
inter-tied system. The off-grid (stand alone) systems are mostly used where there is no utility
grid service. It is very economical in providing electricity at remote locations especially rural
banking, hospital and ICT in rural environments.
9
PV systems generally can be much cheaper than installing power lines and step-down
transformers especially to remote areas.
Solar modules produce electricity devoid of pollution, without odour, combustion, noise and
vibration. Hence, unwanted nuisance is completely eliminated. Also, unlike the other power
supply systems which require professional training for installation expertise, there are no moving
parts or special repairs that require such expertise. [6]
Figure 2.5 Principle of operation of solar cell.
2.7.1.1 Basic Components of Solar Power
The major components include P.V modules, battery and inverter. The most efficient way to
determine the capacities of these components is to estimate the load to be supplied. The size of
the battery bank required will depend on the storage required, the maximum discharge rate, and
the minimum temperature at which the batteries will be used when designing a solar power
system, all of these factors are to be taken into consideration when battery size is to be chosen.
Lead-acid batteries are the most common in P.V systems because their initial cost is lower and
also they are readily available nearly everywhere in the world.
Deep cycle batteries are designed to be repeatedly discharged as much as 80 percent of their
capacity and so they are a good choice for power systems. Figure 2.6 is a schematic diagram of a
typical Photovoltaic System.
10
Inverter
Solar Panel
Controller
Load
80-380
Battery
A/C
Figure 2.6 Photovoltaic System
2.7.1.2 Photovoltaic (P.V) Solar Modules
The photovoltaic cell is also referred to as photocell or solar cell. The common photocell is made
of silicon, which is one of the most abundant elements on earth, being a primary constituent of
sand. A Solar Module is made up of several solar cells designed in weather proof unit. The solar
cell is a diode that allows incident light to be absorbed and consequently converted to electricity.
The assembling of several modules will give rise to arrays of solar panels whose forms are
electrically and physically connected together.
There are three main types of photovoltaic solar panels for both commercial and residential use.
They are;
•
Monocrystalline
•
Polycrystalline
•
Amorphous Silicon also called "Thin Film"
All three types of solar panels have both advantages and disadvantages depending on the end
user's budget, the size and type of environment where they are used and the expected output of
the system.
Monocrystalline Photovoltaic Solar Panel
They are made from a large crystal of silicon. Monocrystalline solar panels are the most
efficient and most expensive panels currently available. Because of their high efficiency, they
are often used in applications where installation square footage is limited, giving the end user the
maximum electrical output for the installation area available.
11
Figure2.7. Monocrystalline solar panel
Polycrystalline Photovoltaic Solar Panel
Characterized by its shattered glass look because of the manufacturing process of using multiple
silicon crystals, polycrystalline solar panels are the most commonly seen solar panels. A little
less efficient than Monocrystalline panels, but also less expensive.
Figure 2.8 Polycrystalline solar panel
Amorphous Silicon "Thin Film" Photovoltaic Solar Panel
These panels can be thin and flexible which is why they are commonly referred to as "Thin Film"
solar panels. Amorphous silic0n solar panels are common for building integrated photovoltaics
(BIPV) applications because of their many application options and aesthetics. They are cheaper
and are not affected by shading. Drawbacks are low efficiency, loss of wattage per sq. ft.
installed and heat retention.
They can be manufactured using silicon, copper indium diselenide (CIS) or cadmium telluride
(CdTe)
12
Figure 2.9 Amorphous Silicon "Thin Film" Solar Panel
To determine the size of PV modules, the required energy consumption must be estimated.
Therefore, the PV module size in Wp is calculated as equation (2.1)
Daily energy Consumption
(2.1)
Isolation x efficiency
Where Isolation is in kWh/m2/day and the energy consumption is in watts or kilowatts.
2.7.1.3 Batteries and Batteries Sizes of the Solar System
As mentioned above, the batteries in use for solar systems are the storage batteries, otherwise
deep cycle motive type. Various storages are available for use in photovoltaic power system,
The batteries are meant to provide backups and when the radiance is low especially in the night
hours and cloudy weather. The battery to be used:
(a) Must be able to withstand several charges and discharge cycle
(b) Must be low self-discharge rate
(c) Must be able to operate with the specified limits.
The battery capacities are dependent on several factors which includes age and temperature.
Batteries are rated in Ampere-hour (Ah) and the sizing depends on the required energy
consumption. If the average value of the battery is known, and the average energy consumption
per hour is determined. The battery capacity is determined by the equations 2a and 2b
BC = (2×f×W)/Vbatt
(2a)
Where BC – Battery Capacity
f – Factor for reserve
W – Daily energy
13
Vbatt – System DC voltage
The Ah rating of the battery is calculated as:
(2.2)
2.7.1.4 Charging Electronics (Controllers)
The need for Charging Controllers is very important so that overcharging of the batteries can be
prevented and controlled. The controllers to be used required the following features [8]:
Prevent feedback from the batteries to PV modules
It should have also a connector for DC loads
It should have a work mode indicator.
2.7.1.5 Solar Inverters
The Solar inverters are electrical device meant to perform the operation of converting D.C from
array or battery to single or three phase A.C signals. For P.V Solar Systems, the inverters are
incorporated with some inbuilt protective devices. These include:
Automatic switch off if the array output is too high or too low.
Automatic re-start
Protecting Scheme to take care of short circuit and overloading
Generally the inverter to be used that would produce the quality output must have the following
features
Overload protections
Miniature Circuit Breaker (MCB)
Low - battery protection
Constant and trickle charging system
Load status indicator
2.7.2 Wind Energy
Wind Power is energy extracted from the wind, passing through a machine known as the
windmill. Electrical energy can be generated from the wind energy. This is done by using the
energy from wind to run a windmill, which in turn drives a generator to produce electricity. The
windmill in this case is usually called a wind turbine. This turbine transforms the wind energy to
14
mechanical energy, which in a generator is converted to electrical power. An integration of wind
generator, wind turbine, aero generators is known as a wind energy conversion system (WECS).
2.7.2.1 Components of Wind Energy Project
Modern wind energy systems consist of the following components.[8]:
A tower on which the wind turbine is mounted;
A rotor that is turned by the wind;
The nacelle which houses the equipment, including the generator that converts the
mechanical energy in the spinning rotor into electricity.
The tower supporting the rotor and generator must be strong. Rotor blades need to be light and
strong in order to be aerodynamically efficient and to withstand prolonged used in high winds.
In addition to these, the wind speed data, air density, air temperature need to be known amongst
others
2.7.2.2 Wind Turbine
A wind turbine is a machine for converting the kinetic energy in wind into mechanical energy.
Wind turbines can be separated into two basic types based on the axis about which the turbine
rotates. Turbines that rotate around a horizontal axis are more common. Vertical-axis turbines
are less frequently used.
Wind turbines can also be classified by the location in which they are used as Onshore, Offshore,
and aerial wind turbines [9]
2.7.2.3 Wind power modeling
The block diagram in figure 2.10 shows the conversion process of wind energy to electrical
energy.
Wind speed
scale & shape
factor
Wind turbine
Generator
(Mechanical)
(Electrical Energy)
Electrical
power output
Figure 2.10 Block diagram for conversion process of wind energy to electrical energy
15
2.7.2.4 Power content of wind
The amount of power transferred to a wind turbine is directly proportional to the area swept out
by the rotor, to the density of the air, and the cube of the wind speed.
The power P in the wind is given by.
P = ½ Cp. ρ.A. V´3 …………………………………
(2.3)
Where Cp is the turbine power coefficient. A theoretical maximum value of 0.593 has been
proposed for Cp
ρ = air density (kg/m3),
A is the rotor swept area (m2),
Where r is the rotor blade radius (m) and V´ = mean wind speed (ms-1)
16
CHAPTER THREE
3.0 Data Collection
To design the solar-wind hybrid power system for pumping system the following are the data
collected
3.1FIELD DATA
3.1.1 Data Collected From Site
Location of the site is latitude 4.890 South and longitude 34.90 East
The area proposed for vegetables is 5 Acres
Number of houses around the scheme is 20 houses
Type of the soil is loam
Depth of the well is 80 meters
Height from the ground to the base of the overhead tank is 10 meters
3.1.2 Metrological Data
Table 3.1 below shows the average wind speed in meter per second (m/s) in Singida Region for
twelve months.
JAN
Speed 9.169
FEB
MAR APR
8.277
8.397
MAY
7.101 8.427
JUN
JUL
AUG
SEP
OCT NOV DEC
8.913
8.03
8.079
9.117
8.138 6.360 6.588
(m/s)
Source: (TMA)
Table 3.1 Average wind speed (m/s) in Singida Region
Table 3.2 below shows the average daily solar radiation in Kilowatt-hour per square meter per
day (kWh/m2/day) in Singida Region for two years (2012 and 2013)
JAN
FEB
MAR APR
MAY JUN
JUL
AUG SEP
OCT NOV DEC
2012
5.73
6.01
6.04
5.53
5.21
5.69
6.05
6.38
6.87
6.80
6.27
5.74
2013
5.90
6.21
6.15
5.97
5.84
6.06
6.26
6.62
6.89
6.76
6.15
5.89
Source: (TMA)
Table 3.2 Average solar radiation in (kWh/m2/day)
17
3.1.3 Vegetable Spacing And Water Requirement Per Day
The following is the table for selected vegetables their average spacing and daily water
requirements in liters.
Vegetable
Spacing in feet
Water needed in
Liter per day
(L/day)
Cabbages
1.5
1.5
Chinese
1
2
Spinach
1
2
Tomatoes
2
1.5
Table 3.3Vegetable spacing and water requirement per day
3.2 TECHNICAL DATA
3.2.1 Estimated Load Demand for the Houses around the Scheme
Table 3.4below shows the estimated load demand for the houses around the scheme
Appliance
Quantity
Power
Total Watt
Time of use
[w]
[W]
[Hours]
Wh/day
kWh
Lightings
20
18
1440
4
5760
5.76
FM Radio
20
12
240
5
1200
1.2
Fan
20
60
1200
2
2400
2.4
Phone charger
20
2.75
220
0.5
110
1.1
9470
9.47
Total
3100
Table 3.4 Estimated Load Demand
3.2.2 Available Solar Modules in the Market
Table 3.5 below shows specifications of solar modules available in the market
18
Type
JS
280P
285P
290P
295P
300P
Max-Power
Pm(W)
280
285
290
295
300
Power
Tolerance
Max-Power
Voltage
Max-Power
Current
Open Circuit
Voltage
Short Circuit
Current
Max-System
Voltage
Cell
Efficiency
Module
Efficiency
Number type
and
arrangement
of cells
Cell Size
%
Max-Series
Fuse
Pm
Temperature
Coefficient
Isc
Temperature
Coefficient
Voc
Temperature
Coefficient
NOCTNominal
Operating
Cell
Temperature
Operating
Temperature
(A)
0-3
Vm(V)
35.80
36.00
36.20
30.40
Im(A)
7.83
7.93
8.03
8.12
8.23
Voc(V)
44.00
44.05
44.10
44.15
44.20
Isc(A)
8.56
8.60
8.64
8.68
8.72
VDC
1000
nc(%)
16.00
16.30
16.59
16.80
17.19
nm(%)
14.45
14.69
14.98
15.24
15.52
72pcs.
Polycrystalline
Silicon (61*2)
72pcs.
Polycrystalline
Silicon (61*2)
72pcs.
Polycrystalline
Silicon (61*2)
72pcs.
Polycrystalline
Silicon (61*2)
156*156
(Square)
156*156
(Square)
156*156
(Square)
156*156
(Square)
72pcs.
Polycrystallin
e Silicon
(61*2)
156*156
(Square)
mm
15
(%/0C)
-0.45
(%/0C)
0.05
-0.32
(%/0C)
46
-40 to 85
0
C
Table 3.5 below shows solar panels available in the market
19
3.2.3 Wind Turbine Available In the Market
Table 3.6 below shows specification of wind turbine
Rotor Diameter
5.0 meters
Turbine Body
cast Iron
Turbine Weight
310Kg
High-speed control
Electrical Braking ,Swing (slow
down)
Over-speed Protection
Electrical Braking (shut down)
Electrical Voltage
DC 48V (Grid-off ) /
(Grid-tied )
Rated Power
5000Watts at 9m/s
Max Power
7500Watts at 10m/s
Start up wind speed
3m/sec
Rated wind speed
10m/sec
Survival wind speed
40m/sec
Kilowatt Hours per Month
3600Kwh/mo at 10m/s
Temperature
-40~+60 Celsius degree
Wind energy ratio
45%
Tower Type
Guy Wire Tower / Free Stand
Tower / Manual hydraulic Tower /
Lever type Free Stand Tower
Height
6m/7m/9m/10m/12m/15m/20m
Noise level(decibel)
≤70db
Composition
Generator, Generator Body, Tail
Table 3.6 Wind Turbine Specification
20
DC240V
3.2.4 Specification for Solar Charge Controllers
The following table shows the specification for solar charge controller
Solar Charger
Controller
Power
Tarom
2070
System Voltage
70A
Max Module input
short circuit current
70A
Max load output
current
Max Self
Consumption
End of charge
voltage (float)
Boost Charge
Voltage
Equalization
Voltage
Recommended Set
point (SOC/LVD)
Deep discharge
protection
(SOC/LVD)
Ambient
temperature allowed
Terminal size
(fine/single wire)
Enclosure protection
class
Weight
Dimension L
330mm
Power
Tarom
2140
12V/(24V)
Power
Tarom
4055
Power
Tarom
4110
48V
Power
Tarom
4140
140A
55A
110A
140A
70A
55A
55A
70A
14mA
13.7(27.4V)
54.8V
14.4V(28.8V)
57.6V
14.7V(29.4V)
58.8V
-100C to 600C
50mm2/70mm2
IP 65
10kg
360mm
330mm
360mm
Table 3.7 Solar charge controller specifications
3.2.5 Specifications for Inverter
Table 3.8 below shows specifications for some inverter available in the market.
21
360mm
Model
Axpert KS 1K
Axpert KS 2K
Axpert KS 3K
Axpert KS 4K
Axpert KS 5K
RATED
POWER
INPUT
Voltage
Selectable
Voltage Range
Frequency Range
OUTPUT
AC Voltage
Regulation (Batt.
Mode)
Surge Power
Efficiency (Peak)
Transfer Time
Waveform
BATTERY
Battery Voltage
Floating Charge
Voltage
Overcharge
Protection
Maximum
Charge Current
SOLAR
CHARGER
(OPTION)
Charging Current
Maximum PV
Array Open
Circuit Voltage
Standby power
Consumption
PHYSICAL
Dimension, D x
W x H (mm)
Net Weight (kg)
OPERATING
ENVIRONMEN
T
Humidity
Operating
Temperature
Storage
Temperature
3.2.6 Specifications for Wind Turbine Controller
Table 3.9 below shows Technical Parameters of the FKJ-B (PWM) Off - Grid Wind Turbine
Controller 5KW
Type
Wind turbine rated power
Wind turbine max. power
Battery
Function
Display mode
Display content
PWM constant pressure voltage
3-phase load voltage of the wind turbine
Wind turbine recovery charging voltage
Low-voltage of the battery
Self-provided connecting wire of the battery
PWM fuse
Charging fuse
Work environment temperature
Relative humidity
Noise (1m)
Degree of protection
Cooling method
Communication interface (optional)
*Temperature compensation (optional)
Size of the controller
Weight of the controller
Size of the load
Weight of the load
5kW-48Vdc 5kW-120Vdc 5kW-240Vdc
5kW
5kW
5kW
10kW
10kW
10kW
48Vdc
120Vdc
240Vdc
Regulator, charge, control
LCD
Wind turbine voltage, wind turbine current,
wind turbine power, battery voltage, charge
current
>56Vdc
>135Vdc
>280 Vdc
58±1Vdc
145±2Vdc
290±5Vdc
54±1Vdc
135±2Vdc
280±5Vdc
40±1Vdc
100±2Vdc
200±5Vdc
>20mm²
>10mm²
>6mm²
125A
63A
40A
160A
63A
50A
-30-60°C
<90% No condensation
<40dB
IP20(Indoor)
Forced air cooling
RS485/USB/GPRS/Ethernet
-4mv/°C/2V,-35°C~+80°C,Accuracy:±1°C
500*440*290 mm
21 Kg
660*510*450 mm
31 Kg
Table 3.9 Wind Turbine controller specifications
23
CHAPTER FOUR
DATA ANALYSIS
INTRODUCTION
This chapter will provide necessary calculation which can be helpful in the select of appropriate
size of different hardware components in the completion of the project. Firstly, it will show
calculation of total volume of water required daily, calculating the rate of the pump to be
installed and total power to be generated using hybrid power. Nextly, calculating the number of
PV modules required, charge controller and the size of the wind turbine..
4.1 CALCULATING THE AMOUNT OF POWER REQUIRED BY PUMP
4.1.1 Determination of Total Volume of Water Required Daily
To calculate volume of water required daily, total area of the land to be irrigated, average amount
of water required per root and total number of roots within the area should be considered.
Total area of the land to be irrigated is 5Acres, which is equivalent to 20,234.28m2. This value is
based on the conversion shown below;
1Acre
Then; 5Acres
2
,
2
20234.28m2
Average spacing of the roots is given by;
(4.1)
That is,
1.375ft;
This is the same to 0.4191m, since (1.375 × 0.3048m = 0.4191).
Squaring the average spacing to get the square area,
24
We have, 0.1756m2
Therefore in a square of 1m2 there are
roots
5.693 roots.
Total number of roots is given by;
Area (m2) × Number of roots per m2;
20234.28m2×5.693 roots/m2
115199.988 roots
Average volume of water needed per root is given by;
(4.2)
1.75 liters
Total volume (m3) of water required for irrigation daily is given by;
Average volume of water per root (liter/root) Number of roots
1.75liter 115199.988 roots
201599.979 liters
4.1.2 Determination of Flow Rate
Equation above gives the total volume of water required for irrigation of vegetables which
occupy an area of 5Acres, and it is given in liters. This value (201599.979 liters) can be
represented in meter cube (m3) by dividing by 1000, since 1000 liters are equivalent to 1m3.
Therefore,
201599 979 liters
201.599m3
25
Total hours to lift water from the well to the overhead tanks is total hours when energy from
solar and wind is generated, For Singida region it is from 2am to 5pm, hence about 9 hours.
The flow rate is given by;
(4.3)
[m3/sec]
-3
5.599
[m3/sec]
4.1.3 Determination of Rating of the Pump
The type of energy required to pump water from the well to the overhead tank is the potential
energy, which is given by,
Pe = mgH
Where;
(4.4)
Pe
is the potential energy [J]
m
is the total mass of water [kg]
g
is acceleration due to gravity [m/s2]
H
is head [m]
Since power [W] is given by;
,
P=
(4.5)
mgH
But;
ρ
Where ;
V= Volume of water to be pumped,
So,
Therefore;
m=ρV,
P=
ρVgH
or [ ρgH]
26
[ ] is the volume flow rate [m3/s],
Let
Q represents [ ],
P=Q ρgH
Then;
P=
ρgH
(4.6)
Therefore, the rating of the pump is given by the following equation;
P=Q ρgH
Where;
P
is the power rating of the pump [Watts]
Q
is the flow rate [m3/sec]
H
is the total head [m]
g
is the acceleration due to gravity [m/s2]
is the density of water [kg/m3]
P = 5.599
-3
=4943.357 Watts
To obtain the input power to the pump, that is the power of the motor pump, we divide with the
efficiency of the pump. Take the efficiency of the pump to be 80%.
We get;
4943.357
0.8 = 6179.196 Watts.
27
4.1.4 Block Diagram of the Proposed Solar-Wind Hybrid Power System
Figure 4.1 Block diagram of the proposed Solar-Wind Hybrid Power System
4.1.5 Circuit Diagram of the Proposed System
Figure 4.2 Circuit diagram of the complete power system
4.2 ANALYSIS ON POWER TO DESIGNED
Designed power is given by;
Pdes=Ksaf Preq
(4.7)
28
Where Pdes
is Designed power
Preq
is required power
Ksaf
is Safety factor (1.25)
T0tal power required (Preq) = Motor power + Village power
=6179.176+3100=9279.176W
12kW
Pdes=1.25 9279.176=11598.97
This value of power should be generated by combination of Solar pv system and Wind turbine
system.
Let the ratio for power generated by the solar pv system and wind turbine system be 1:2
respectively, that is; solar pv system will contribute one third (1/3) of the total power required
and three third (2/3) will be contributed by wind turbine system.
For this case power to be generated by;
i.
Solar pv system is given by;
1/3 12kW=4kW
ii.
Wind turbine system is given by;
2/3 12kW.
4.3 SOLAR PV SYSTEM DESIGN
Solar PV system includes different components that will be according to the total load of the
motor and the load of the householders around a scheme. The major components for solar PV
system are solar charge controller, inverter and loads (appliances).
4.3.1. Determine power consumption demands
The first step in designing a solar PV system is to find out the total power and energy
consumption of all loads that need to be supplied by the solar PV system as follows:
To calculate total Watt-hours per day needed from the PV modules
29
It is given by adding the Watt-hours needed for pump and house appliances together to get the
total Watt-hours per day which must be delivered to the appliances.
The input power to the motor is 6179.196 Watts, and its running time is 10 hours, therefore
Energy to be consumed by a pump is given by;
6179.196
Wh/day
Total energy of the house around the village is 9470 Wh/day.
Total energy to be supplied by the proposed system is given by;
9470
71261 96Wh/day
But solar PV system will produce 1/3 of the total energy required,
Total Watt-hour required by PV system is;
1/3 71261.96Wh/day=23753.98 23754Wh/day
4.3.2. Size the PV modules
Since different size of PV modules produce different amount of power. To find out the sizing of
PV module, the total peak watt produced needs. The peak watt (Wp) produced depends on size
of the PV module and climate of site location. We have to consider “panel generation factor”
(PGF) which is different in each site location.
PGF depends on
•
the lowest average insolation over a year, which is obtained from table 3.2 as 5.2
kWh/m2/day
•
the correction factors, including
15% for temperature above 250C
5% for losses due to sunlight reflection
10% for losses due to sunlight absorption
5% for losses due to dirt
30
10% allowance for solar module ageing
Therefore, correction factor is,
0.85
.
PGF=0.62 Average insolation
=0.62
Therefore, the size of PV module is given by;
(4.8)
=9560.43Wp
Calculate the number of PV panels for the system
Divide the answer obtained in item 2.1 by the rated output Watt-peak of the PV modules
available.
Available module having a Maximum power of 280 W,
The number of module is given by;
9560 43
=34.14
modules
Result of the calculation is the minimum number of PV panels.
So this system should be powered by at least 36 modules of 280Wp.
Module model to be selected is JS 280P (Table 3.4)
(4.9)
Number of modules in series =
For the system above 5kW, it is recommended to choose system voltage of 48V.
Number of modules in series is =
Therefore two modules of 24V will be connected in series in each string.
31
=36/2=18
Number of modules in parallel Nmparallel=
There are 18 numbers of strings in the system.
Inverter sizing
An inverter is used in the system where AC power output is needed. The input rating of the
inverter should never be lower than the total watt of appliances. The inverter must have the same
nominal voltage as your battery.
Total Watts of appliances is 3100 W
Inverter size should be 25-30% greater than the load,
Therefore the size of inverter will be 3100+25 %( 3100) =3875VA
The standard value of inverter is 4kVA.
The inverter to be chosen is Axpert Ks 4k with 4000VA and 3200W (Table 3.9)
Solar charge controller sizing
PV module specification
Pm = 280 Wp
Vm = 35.8 Vdc
Im = 7.83 A
Voc = 44.00 A
Isc = 8.56 A
According to standard practice, the sizing of solar charge controller is to take the short circuit
current (Isc) of the PV array, and multiply it by 1.3
Solar charge controller rating (Irated) = Total short circuit current of PV array x 1.3
Solar charge controller rating (Irated) = (18 strings x 8.56 A) x 1.3 = 200.3A
32
A
Number of charge controller required is given by equation below;
Ncont=
(4.10)
Selected controller current is 110A,
Ncont=
= 1.818
Controllers
Therefore two (2) charge controllers with input maximum short-circuit current of 110A, 48vdc
should be used. Power Tarom4110 is selected (Table 3.6)
4.4 WIND POWER SYSTEM DESIGN
Under constant acceleration, the kinetic energy E of an object having mass m and velocity v is
equal to the work done W in displacing that object from rest to a distance s under a force F,
That is;
E=W=Fs
(4.11)
According to Newton‟s Law, we have;
F=ma
(4.12)
E=mas
(4.13)
Hence;
Using the third equation of motion;
v2=u2+2as
(4.14)
a= (v2 u2) 2s
(4.15)
33
Since the initial velocity of the object is zero, i.e. u=0, we get;
a=v2
(4.16)
Substituting it in equation (1), we get that the kinetic energy of a mass in motions is;
E= mv2
(4.17)
The power in the wind is given by the rate of change of energy;
P=
= v2
(4.18)
As mass flow rate is given by;
=ρA
(4.19)
And the rate of change of distance is given by;
=v
(4.20)
We get;
=ρAv
(4.21)
Hence, from equation (3), the power can be defined as;
P= ρAv3
(4.22)
A German physicist Albert Betz concluded in 1919 that no wind turbine can convert more than
16/27 (59.3%) of the kinetic energy of the wind into mechanical energy turning a rotor. To this
34
day, this is known as the Betz Limit or Betz' Law. The theoretical maximum power efficiency
of any design of wind turbine is 0.59 (i.e. no more than 59% of the energy carried by the wind
can be extracted by a wind turbine). This is called the “power coefficient” and is defined as [10];
CPmax=0.59
Also, wind turbines cannot operate at this maximum limit. The CP value is unique to each turbine
type and is a function of wind speed that the turbine is operating in. Once we incorporate various
engineering requirements of a wind turbine - strength and durability in particular – the real world
limit is well below the Betz limit with values of 0.35-0.45 common even in the best designed
wind turbines. By the time we take into account the other factors in a complete wind turbine
system - e.g. the gearbox, bearings, and generator and so on, only 10-30% of the power of the
wind is ever actually converted into usable electricity. Hence, the power coefficient needs to be
factored in equation (4) and the extractable power from the wind is given by;
Pavail= ρAv3CP
(4.23)
When considering the efficiency of gearbox/bearing (Nb which varies from 50%-80%) and
generator (Ng which ranges from 95% and above), equation (4.23) above can be changed into;
Ptotal= CP Nb Ng ρ Av3
(4.24)
4.4.1 Calculating the size of wind turbine
Total power required to be generated by wind turbine is 8kW
The average wind speed is 8.05 m/s at height of 10m.
Let
Cp=0.45
Nb=0.65
Ng=0.94
The diameter of the turbine can be calculated by the following calculation,
Ptotal= CP Nb Ng ρ Av3
35
(8.05)3
Ptotal=0.5
But, Area A= D2
Let D=10m
A=
2
=78.5398m2
(8.05)3
Ptotal=0.5
Ptotal=6973.21W
4.4.2 Number of turbines required
To get the number of turbine we divide available power (8000W) with the power of the single
turbine selected (6973W)
=1.1
Number of turbine required will be two turbines
4.4.3
Graph of the average output power generated by the wind turbine.
To draw the graph consider the equation (4.24) above
Ptotal= CP Nb Ng ρ Av3
.
From the table of specifications of the wind turbine,
Rated wind speed is 9 m/s
Rated power is
5kW
Rotor diameter is
5m
Tower Height is
20m
Since wind turbines are affected by wind gradient. Vertical wind-speed profiles result in different
wind speeds at the blades nearest to the ground level compared to those at the top of blade travel,
and this in turn affects the turbine operation
36
For wind turbine engineering, an exponential variation in wind speed with height can be defined
relative to wind measured at a reference height of 10 meters as [11]:
Vw(h)=V10
h
h10
Where:
Vw(h)= velocity of the wind at height h, [m/s]
V10= velocity of the wind at height h10, = 10 meters [m/s]
= Hellman exponent
The exponent, , is an empirically derived coefficient that varies dependent upon the stability of
the atmosphere. For open agricultural areas with limited presence of middle height obstacles
(6-8) m this exponent is approximately 0.16
Wind speed from table 3.1 must be converted in the base of 20m/s height.
I have selected 20m because it is the highest height of the tower from the specification table, also
can ensure more wind speed.
From Vw(h)=V10
h
h10
Vw(20)=V10
10
Also from relation of power generated with wind velocity,
P V3
Let
P1 is the power at 9m/s, which is 5000W
P2 is the power at Vw(20)
The output power can be obtained as follows
37
P2=5000
Where Vw(20) is the average velocity of the wind for each month at a height of 20m/s.
Month
Speed at 10m
New Speed at 20m
January
9.169
10.24
Power at new
speed at 20m high
7364
February
8.277
9.25
5428
March
April
May
June
8.397
7.101
8.427
8.913
9.38
7.93
9.42
9.96
5660
3382
5733
6777
July
8.03
8.97
4950
August
8.079
9.03
5050
September
October
November
9.117
8.138
6.360
10.19
9.09
7.11
7257
5152
2465
December
6.588
7.36
2743
Table 4.1 Table of power generated by a single turbine at 20m tower height
The graph of the power generated by a single wind turbine is shown below
8000
Power generated by a single turbine
7000
Power in Watts
6000
5000
4000
3000
2000
1000
0
Months
Figure 4.3 A Graph of Power Generated by a single Turbine
38
4.5 CONDUCTOR SIZING
The proper sizing of an electrical (load bearing) cable is important to ensure that the cable can:
Operate continuously under full load without being damaged
Withstand the worst short circuits currents flowing through the cable
Provide the load with a suitable voltage (and avoid excessive voltage drops)
(optional) Ensure operation of protective devices during an earth fault
The wiring system I selecting is single-core cables in conduit (See App.1) Referenced as B1.
Correction factors which I select are;
k1
Due to ambient temperature which is 0.94 (see App.3)
k2
Due to arrangement (Bunched in air, on a surface, embedded or enclosed) which
is 1.0 see (App.7).
Therefore the overall correction factor k1.k2 is 0.94
4.5.1 Cable sizing from pv module to Solar charge controller
Rated (base) current (Ib)=Nmparallel
18
Ic=
Ic is the corrected load current, to be compared to the current-carrying capacity of the considered
cable.
Ib is the rated (base) load current.
Ic=
= 204.89A
For each array size of cable will be 204.89/18= 11.38A
4.5.2 Cable sizing from wind turbine to Wind turbine controller
Ib=
=
= 156.25A
39
Ic=
= 166.22A
4.5.3 Cable sizing from Solar turbine controller to the busbar
Ib= Maximum load output current of the controller (55A)
Ic=
= 58.51A
4.5.4 Cable sizing from busbar to inverter
Ib=
=
Ic=
= 104.17A
= 110.82A
4.5.5 Cable sizing from Wind turbine controller to busbar
Ib= Charging fuse current (160A)
Ic=
= 170.21A
4.5.6 Busbar sizing
Busbar rating current is given by;
Ib=
Ib=
√
(for three phase system)
(For DC System)
for two sources(see App.9)
Pmax total= Total pv power + Total turbine power
36
Ib=
= 130.625A
Therefore busbar should be capable of carrying 130.625A
A summarized table for size of cables
40
Cable position
Ib (A)
Ic (A)
Size (mm2)
PV Module-Solar Charge Controller
Each Array
192.6
10.7
204.89
11.38
95
1.5
Wind Turbine-Wind Turbine Controller
156.25
166.22
70
Solar Charge Controller-Busbar
55
58.51
16
Wind Turbine Controller-Busbar
160
170.21
70
Busbar-Inverter
104.17
110.82
35
4.6 INSTALLATIONS
Installation of solar modules will be as follows
Installation angle is given by;
0
-4.89+15=10.11 facing north direction
Modules will be installed on top of metal support structure on the concrete structure
For wind turbines, they will be installed According to the guide of installation manual
4.7 COST ESTIMATION
The table below shows the estimated cost for the whole project
41
Component
Model
Quantity
Unit price
Total
Modules
JS-280P
36
840000
30240000
Solar Charge
Power Tarom
2
865000
1730000
controller
4110
Inverter
Axpert KS 4K
1
1096000
1096000
Wind Turbine
HAWT 5kW
2
23900000
47800000
Wind Regulator
FKJ-B (PWM)
2
1086000
2172000
SUBTOTAL
83038000
Other BOS Cost (wires, fuses, circuit breakers etc)
16607600
TOTAL COST
99645600
Cost per component = Quantity
Unit price
Other Balance of system Component (BOS) Cost = 20% of subtotal
CONCLUSION
This system is designed to be used during dry season for which in Singida region there is no rain
at all, and the sky is almost clear. Also it will be used during rainy season as standby system.
The idea of using two renewable sources is important because they are intermittent, whereby due
to necessity of water to the vegetation, choosing one source will be dangerous to vegetation
growth and hence low production.
The project which I have designed is reliable due to highly availability of these energy resources
in Singida region and it will be affordable although starting cost may be slightly large.
RECOMMENDATIONS
To make the system to be more reliable two recommendations should be noted
1) To include batteries to ensure no anytime the system will generate inadequate power or
no power at all, or
2) To install reserve tanks which will serve water during maintenance time
42
References
[1] AskDefinition. Irrigation.
http://irrigation.askdefine.com/ , 29/12/2013
[2] Rohit, V.N. (2013). “Micro Controller Based Automatic Plant Irrigation System”
International Journal of Advancements in Research & Technology, Vol.2, (No.4): pg 194.
[3] TORO. Advantages of Drip Irrigation. Drip Tips.
http://driptips.toro.com/?p=417 , 25/11/2013
[4] Irrigation Tutorial. Irrigation Pump Tutorial Selecting a Pump Type.
http://www.irrigationtutorials.com , 12/12/2013
[5] Salah, M.(2008). Simulation of a Hybrid Power System Consisting of Wind Turbine, PV,
Storage Battery and Diesel Generator with Compensation Network:
Design, Optimization and Economical Evaluation. Faculty of Graduate
Studies. An-Najah National University, Palestine. Master‟s Thesis.
[6] Hybrid Solar and Wind Power: An Essential for Information Communication Technology
Infrastructure and People in Rural Community
www.arpapress.com/Volumes/Vol9Issue1/IJRRAS_9_1_15.pdf
,20/12/2013
[7] M. Thomas (Ed) “Solar Electricity”, John Wiley and Sons Ltd, Chichester, 2nd Edition.
(2004)
[8] U.K Mehta. “Principle of Electronics”, S.Chand & Company Ltd. New Delhi. (2004)
[9] Technical brief on Wind Electricity Generation:
http://www.windpower.org, 21/12/2013
[10] The Royal Academy of Engineering: Wind Turbine Power Calculation
http://www.raeng.org.uk/education/diploma/maths/pdf , 10/03/2014
[11] Wikipedia: Wind Gradient
http://en.wikipedia.org/wiki/Wind_gradient , 06/04/2014
43
APPENDIX
Appendix 1 WORK SCHEDULE
Oct
Nov
Dec
Jan
Feb
A
B
C
D
E
F
G
KEY
A
Selection of Project Title
B
Title Defending
C
Literature Review and Consultation
D
Data Collection
E
Data Analysis
F
Report Writing
G
Submission of Report
1
Mar
Apr
May
Jun
Appendix 2 Examples of wiring systems and reference methods of installations
An illustration of some of the many different wiring systems and methods of installation is
provided in Figure App.1.
Several reference methods are defined (with code letters A to G), grouping installation methods
having the same characteristics relative to the current-carrying capacities of the wiring systems.
Item No.
Methods of
Description
Reference method of
installation
installation to be
used to obtain
current-carrying
capacity
1
Insulated conductors or A1
single-core
cables in
conduit in a thermally
insulated wall
2
Multi-core cables in conduit A2
in a thermally insulated
wall
3
Insulated conductors or
single-core
cables in
conduit on a wooden, or
masonry wall or spaced less
than 0,3 x conduit diameter
from it
Multi-core cable in conduit
on a B2 wooden, or
masonry wall or spaced less
than 0,3 x conduit diameter
from it
Single-core or multi-core
cables: - fixed on, or spaced
less than 0.3 x cable
diameter from a wooden
wall
On un-perforated tray
4
5
6
2
B1
B2
C
C
Item No.
Methods of
installation
Description
Reference method of
installation to be
used to
obtain currentcarrying
capacity
E or F
7
On perforated tray
8
Bare or insulated G
conductors
on
insulators
Multi-core cables in D
conduit or in cable
ducting in the ground
9
10
Single-core cable in D
conduit or in cable
ducting in the ground
App.1 Examples of methods of installation (part of table 52-3 of IEC 60364-5-52)
Maximum operating temperature:
The current-carrying capacities given in the subsequent tables have been determined so that the
maximum insulation temperature is not exceeded for sustained periods of time.
For different type of insulation material, the maximum admissible temperature is given in Figure
App 2.
Type of insulation
Temperature limit °C
Polyvinyl-chloride (PVC)
70 at the conductor
Cross-linked polyethylene (XLPE) and
90 at the conductor
ethylene
Mineral (PVC covered or bare exposed to
70 at the sheath
touch)
Mineral (bare not exposed to touch and not in
105 at the sheath
App 2 Maximum operating temperatures for types of insulation (table 52-4 of IEC 60364-5-52)
Correction factors:
3
In order to take environment or special conditions of installation into account, correction factors
have been introduced.
The cross sectional area of cables is determined using the rated (base) load current IB divided by
different correction factors, k1, k2,…
Ic=
Ic is the corrected load current, to be compared to the current-carrying capacity of the considered
cable.
Ambient temperature
The current-carrying capacities of cables in the air are based on an average air temperature equal
to 30 °C. For other temperatures, the correction factor is given in Figure App.3 for PVC, EPR
and XLPE insulation material.
The related correction factor is here noted k1.
Ambient temperature °C
10
15
20
25
35
40
45
50
55
60
65
70
75
80
App.3 Correction factors for ambient air temperatures other than 30 °C to be applied to the
current-carrying capacities for cables in the air (from table A.52-14 of IEC 60364-5-52)
The current-carrying capacities of cables in the ground are based on an average ground
temperature equal to 20 °C. For other temperatures, the correction factor is given in Figure
App.4 for PVC, EPR and XLPE insulation material.
The related correction factor is here noted k2.
4
Ground temperature °C
Insulation
PVC
XLPE and EPR
10
1.10
1.07
15
1.05
1.04
25
0.94
0.96
30
0.89
0.93
35
0.84
0.89
40
0.77
0.85
45
0.71
0.80
50
0.63
0.76
55
0.55
0.71
60
0.45
0.65
65
-
0.60
70
-
0.53
75
-
0.46
80
-
0.38
App.4 Correction factors for ambient ground temperatures other than 20 °C to be applied to the
current-carrying capacities for cables in ducts in the ground (from table A.52-15 of IEC 60364-552)
Soil thermal resistivity
The current-carrying capacities of cables in the ground are based on a ground resistivity equal to
2.5 K.m/W. For other values, the correction factor is given in Figure App.5.
The related correction factor is here noted k3
5
Thermal resistivity, K.m/W
1
1.5
2
2.5
3
Correction factor
1.18
1.1
1.05
1
0.96
App.5 Correction factors for cables in buried ducts for soil thermal resistivities other than 2.5
K.m/W to be applied to the current-carrying capacities for reference method D (table A52.16 of
IEC 60364-5-52)
Based on experience, a relationship exists between the soil nature and resistivity. Then, empiric
values of correction factors k3 are proposed in Figure App.6, depending on the nature of soil.
Nature of soil
k3
Very wet soil (saturated)
1.21
Wet soil
1.13
Damp soil
1.05
Dry soil
1.00
Very dry soil (sun-baked)
0.86
App.6 Correction factor k3 depending on the nature of soil
Grouping of conductors or cables
The current-carrying capacities given in the subsequent tables relate to single circuits
consisting of the following numbers of loaded conductors:
- Two insulated conductors or two single-core cables, or one twin-core cable (applicable to
single-phase circuits);
- Three insulated conductors or three single-core cables, or one three-core cable (applicable
to three-phase circuits).
Where more insulated conductors or cables are installed in the same group, a group reduction
factor (here noted k4) shall be applied.
Figure App.7 gives the values of correction factor k4 for different configurations of
unburied cables or conductors, grouping of more than one circuit or multi-core cables.
6
Arrangeme
nt (cables
touching)
Bunched in
air, on a
surface,
embedded
or enclosed
Single layer
on wall,
floor or unperforated
tray
Single layer
fixed
directly
under a
wooden
ceiling
Single layer
on
a perforated
horizontal
or vertical
tray
Single layer
on ladder
support or
cleats etc.
Number of circuits or multi-core cables
4
5
6
7
8
9
1
2
3
12
16
20
1.00
0.80
0.70
0.65
0.60
0.57
0.54
0.52
0.50
0.45
0.41
0.3
8
1.00
0.85
0.79
0.75
0.73
0.72
0.72
0.71
0.70
0.63
0.62
0.61
No further
reduction factor
for more
than nine circuits
or multi-core
cables
0.94
0.81
0.72
0.68
0.66
0.64
1.00
0.88
0.82
0.77
0.75
0.73
0.73
0.72
0.72
1.00
0.87
0.82
0.80
0.80
0.79
0.79
0.78
0.78
Referenc
e method
s
Methods
A to F
Method
C
Methods
E and F
App.7 Reduction factors for groups of more than one circuit or of more than one multi-core
cable (table A.52-17 of IEC 60364-5-52
Admissible current as a function of nominal cross-sectional area of conductors
IEC standard 60364-5-52 proposes extensive information in the form of tables giving the
admissible currents as a function of cross-sectional area of cables. Many parameters are taken
into account, such as the method of installation, type of insulation material, type of conductor
material, number of loaded conductors.
As an example, Figure App.8 gives the current-carrying capacities for different methods of
installation of PVC insulation, three loaded copper or aluminium conductors, free air or in
ground
7
Nominal cross-sectional
area of conductors
A1
(mm2)