automatic solar irrigation pump control system based on soil moisture sensor (1).doc

AUTOMATIC SOLAR IRRIGATION PUMP CONTROL SYSTEM BASED ON SOIL MOISTURE SENSOR

CHAPTER – 1

INTRODUCTION

This project aims in providing a user friendly, reliable and automated irrigation

pump controlling system for illiterates. Now a day’s technology is running with time, it

completely occupied the life style of human beings. Even though there is such an

importance for technology in our routine life there are even people whose life styles are

very far to this well known term technology. So it is our responsibility to design few

reliable systems which can be even efficiently used by them. This basic idea gave birth to

the project soil moisture sensor based irrigation pump controller and this project aims in

introducing the automation technology into the lives of the illiterates.

The purpose of this project is to monitor soil moisture and control a irrigation

pump using microcontroller powered by solar. This can be achieved by the use of soil

moisture sensor, which senses the water content in the soil. This sensor output is given to

a Microcontroller based control system for further data processing.

This project also consists of relays are used to control the pump motor. Whenever

the soil moisture content goes below some predefined level, and then this information is

sent to Microcontroller based control system. Based on the command received the

Microcontroller switches ON or OFF the irrigation pump motor. This system uses relay

which are controlled by the starter.

Dept. of EEE 1 Trinity College of Engg. & Tech. Knr


The features of the project are:

1. Automatic Soil moisture sensing system.

2. Irrigation motor control.

The major building blocks of this project

1. Regulated Power Supply.

2. Microcontroller.

3. Soil moisture sensor.

4. Electromagnetic relay with driver.

5. Crystal oscillator.

6. Reset.

7. Pump Motor (for water pumping).

8. LCD.



Regulated Power Supply:

Fig.1: Regulated Power Supply

Block Diagram:

Fig: 2: Block diagram



CHAPTER – II

SOLAR PANEL

Solar panel refers either to a photovoltaic module, a solar hot water panel, or to a

set of solar photovoltaic (PV) modules electrically connected and mounted on a

supporting structure. A PV module is a packaged, connected assembly of solar cells. Solar

panels can be used as a component of a larger photovoltaic system to generate and supply

electricity in commercial and residential applications. Each module is rated by its DC

output power under standard test conditions (STC), and typically ranges from 100 to 320

watts. The efficiency of a module determines the area of a module given the same rated

output – an 8% efficient 230 watt module will have twice the area of a 16% efficient 230

watt module. There are a few solar panels available that are exceeding 19% efficiency. A

single solar module can produce only a limited amount of power; most installations

contain multiple modules. A photovoltaic system typically includes a panel or an array of

solar modules, an inverter, and sometimes a battery and/or solar tracker and

interconnection wiring.

Solar panels are devices that convert light into electricity. They are called "solar"

panels because most of the time, the most powerful source of light available is the Sun,

called Sol by astronomers. Some scientists call them photovoltaics which means,

basically, "light-electricity."

A solar panel is a collection of solar cells. Lots of small solar cells spread over a

large area can work together to provide enough power to be useful. The more light that

hits a cell, the more electricity it produces, so spacecraft are usually designed with solar

panels that can always be pointed at the Sun even as the rest of the body of the spacecraft

moves around, much as a tank turret can be aimed independently of where the tank is

going.

These panels are designed with solar cells composed of semiconductor materials.

The main function of Solar panels is, it converts solar energy into DC electrical energy

generally of 12V, which is further used for the rest of the circuit. The number of cells

required and their size depends on the rating of the load. The collection of solar cells can

produce maximum electricity. But, the solar panel must place exactly at right angles to

the sun rays.


https://www.elprocus.com/what-are-the-reasons-behind-silicon-uses-in-electronics/

http://en.wikipedia.org/wiki/Solar_tracker

http://en.wikipedia.org/wiki/Battery_(electricity)

http://en.wikipedia.org/wiki/Inverter_(electrical)

http://en.wikipedia.org/wiki/Solar_cell_efficiency

http://en.wikipedia.org/wiki/Direct_current

http://en.wikipedia.org/wiki/Solar_power

http://en.wikipedia.org/wiki/Photovoltaic_system

http://en.wikipedia.org/wiki/Solar_cell

http://en.wikipedia.org/wiki/Module

http://en.wikipedia.org/wiki/Photovoltaic

http://en.wikipedia.org/wiki/Solar_hot_water_panel

http://en.wikipedia.org/wiki/Photovoltaic


Fig.3 Block Diagram of Solar energy Conversion

Solar Water Pump

A solar water pump has a mini power house at its heart and consists of a calibrated

and matching solar array of modules – tuned with the equivalent power of pump for that

particular application. The solar water pumping system is capable of running all types of

electrical water pumps with applications varying from irrigation to household demands.

Irrigation pumps such as submersible, surface or deep well can also be coupled with drip

irrigation systems to enhance the returns from this configuration.

A typical solar water pumping system is known by the sum total of solar array size

that is required to run the attached pump. A 1000 Wp solar water pump is capable of

drawing and pumping approximately 40,000 litres of water per day from a source that is

up to 10 meters deep. This is sufficient to irrigate about 2 acres of land with regular crops.

A 1000 Wp solar water pump helps save up to Rs 45,000 when compared to equivalent

use of a diesel-operated pump over a year.



CHAPTER – III

COMPONENTS DESCRIPTION

Liquid Crystal Display

Liquid crystal displays (LCD) are widely used in recent years as compares to

LEDs. This is due to the declining prices of LCD, the ability to display numbers,

characters and graphics, incorporation of a refreshing controller into the LCD, their by

relieving the CPU of the task of refreshing the LCD and also the ease of programming for

characters and graphics. HD 44780 based LCDs are most commonly used.

OP-AMP

An operational amplifier ("op-amp") is a DC-coupled high-gain electronic

voltage amplifier with a differential input and, usually, a single-ended output. An op-amp

produces an output voltage that is typically hundreds of thousands times larger than the

voltage difference between its input terminals. Operational amplifiers are important

building blocks for a wide range of electronic circuits. They had their origins in analog

computers where they were used in many linear, non-linear and frequency-dependent

circuits. Their popularity in circuit design largely stems from the fact that characteristics

of the final op-amp circuits with negative feedback are set by external components with

little dependence on temperature changes and manufacturing variations in the op-amp

itself.

The Submersible Pump

This solar system contains a submersible pump, a water tank, an irrigation pump,

associated water pumps. In the site trial the submersible pump is kept in a stainless steel

case, and that is placed in a well pit at the junction of the open channel and the natural

stream course. The pump controller pumps water to the water tank at a particular time

period as set in the control unit. This system is designed with 450W of power and that is

able to pump 2000 liters of water within 60minutes.This power capacity takes account of

the height difference b/n the water tank and the solar submersible pump.

The PV Panels

The photo voltaic cells depend on the size of the pump. A panel is esteemed in

watts of power it can produce. This solar submersible pumping system should be operated



with a PV array capacity in the range of 200 to 500 watts peak, and measured under some

standard test conditions. Plenty number of modules in series & parallel could be used to

get the necessary PV power array power o/p. The o/p power of the PV modules which are

used in the PV array under standard test conditions, that should be a min of 74 watts peak.

Charge Controller

A solar charge controller is very important device in any solar power system. It is

used to maintain proper charging voltages of the batteries. The charge controller controls

current and voltage from the solar panel and charges the battery, and also stops the

charging of the battery from over and undercharging conditions.

Battery

The Battery is an electric device, that is used to store current which is produced

from the solar panel and supplies to the corresponding loads. The number of batteries

required depend on the load requirement.

Inverter

The main function of the inverter is, it converts the battery’s voltage to AC voltage

in order to activate then loads. Therefore, it helps us to run many electronic devices, home

appliances and computers. There are numerous types of inverters available in the market

today.The characteristics of typical inverters like high switching frequency, high

conversion frequency and less harmonic content, and so on.


https://www.elprocus.com/multilevel-inverter-types-advantages/

https://www.elprocus.com/home-inverter/

https://www.elprocus.com/solar-charge-controller-using-mppt-technology/


CHAPTER – IV

SOIL MOISTURE SENSOR

The moisture sensor is buried in the ground at required depth. The working of the moisture sensor is simple and straightforward. The moisture sensor just senses the moisture of the soil. The change in moisture is proportional to the amount of current flowing through the soil.

Fig.4. Circuit Diagram of Soil Moisture Sensor

Most soil moisture sensors are designed to estimate soil volumetric water content

based on the dielectric constant (soil bulk permittivity) of the soil. The dielectric constant

can be thought of as the soil's ability to transmit electricity. The dielectric constant of soil

increases as the water content of the soil increases. This response is due to the fact that the

dielectric constant of water is much larger than the other soil components, including air.

Thus, measurement of the dielectric constant gives a predictable estimation of water

content.

Bypass type soil moisture irrigation controllers use water content information from

the sensor to either allow or bypass scheduled irrigation cycles on the irrigation timer

(Figures 1 and 2). The SMS controller has an adjustable threshold setting and, if the soil

water content exceeds that setting, the event is bypassed. The soil water content threshold

is set by the user. Another type of control technique with SMS devices is “on-demand”

where the controller initiates irrigation at a low threshold and terminates irrigation at a

high threshold.



A moisture sensor is used to sense the level of moisture content present in the

irrigation field. It has a level detection module in which we can set a reference value. This

circuit can be used with analog probes that produce a voltage proportional to soil moisture

such as VG400 probe . The moisture content of the soil is found by using the soil moisture

sensor such as VG400 which produces an equivalent output voltage proportional to the

conductivity between the two probes.

Fig. 5: Soil Moisture Sensor probe.

Moisture sensor module

The prongs should be oriented horizontally, but rotated onto their side – like a

knife poised to cut food – so that water does not pool on the flat surface of the prongs. The

horizontal orientation of the sensor ensures the measurement is made at a particular soil

depth. The entire sensor can be placed vertically, but because soil moisture of ten varies

by depth, this is not usually the desired orientation. To position the sensor, use a thin

implement such as a trenching shovel to make a pilot hole in the soil. Place the sensor into

the hole, making sure the entire length of the sensor is covered. Press down on the soil

along either side of the sensor with your fingers. Continue to compact the soil around the

sensor by pressing down on the soil with your fingers until you have made at least five

passes along the sensor. This step is important, as the soil adjacent to the sensor surface

has the strongest influence on the sensor reading. Removing the sensor when removing the

sensor from the soil, do not pull it out of the soil by the cable! Doing so may break

internal connections and make the sensor unusable



4.1. RELAY

The electromagnetic relay consists of a multi-turn coil, wound on an iron core, to

form an electromagnet. When the coil is energised, by passing current through it, the core

becomes temporarily magnetised. The magnetised core attracts the iron armature. The

armature is pivoted which causes it to operate one or more sets of contacts. When the coil

is de-energised the armature and contacts are released. The coil can be energised from a

low power source such as a transistor while the contacts can switch high powers such as

the mains supply. The relay can also be situated remotely from the control source. Relays

can generate a very high voltage across the coil when switched off. This can damage other

components in the circuit. To prevent this a diode is connected across the coil.

A relay is an electrical switch that opens and closes under the control of another

electrical circuit. In the original form, the switch is operated by an electromagnet to open

or close one or many sets of contacts. A relay is able to control an output circuit of higher

power than the input circuit.

The above diagram shows the representation of a relay. By default when there is

no excitation in the coil the NC (Normally Closed) and C (Common Terminal) are

connected through the contact internally. When the coil is excited by providing the

required coil voltage, the contact switches from the NC to NO (Normally Open) side. In

this case, the C and NC terminals are connected internally.

Fig.6. Circuit Diagram of Relay



The main operation of a relay comes in places where only a low-power signal can

be used to control a circuit. It is also used in places where only one signal can be used to

control a lot of circuits. The application of relays started during the invention of

telephones. They played an important role in switching calls in telephone exchanges. They

were also used in long distance telegraphy. They were used to switch the signal coming

from one source to another destination. After the invention of computers they were also

used to perform Boolean and other logical operations. The high end applications of relays

require high power to be driven by electric motors and so on. Such relays are called

contactors.

TYPES OF RELAYS

1. Latching Relay

Latching relays are also called impulse relays. They work in the bistable mode, and

thus have two relaxing states. They are also called keep relays or stay relays because as

soon as the current towards this relay is switched off, the relay continues the process that it

was doing in the last state. This can be achieved only with a solenoid which is operating in

a ratchet and cam mechanism. It can also be done by an over-centre spring mechanism or

a permanent magnet mechanism in which, when the coil is kept in the relaxed point, the

over-centre spring holds the armature and the contacts in the right spot of a remanent core.

power consumption occurs only for a particular time.

2. Reed Relay

These types of relays have been given more importance in the contacts. In order to

protect them from atmospheric protection they are safely kept inside a vacuum or inert

gas. Though these types of relays have a very low switching current and voltage ratings,

they are famous for their switching speeds.

3. Polarized Relay

This type of relay has been given more importance on its sensitivity. These relays

have been used since the invention of telephones. They played very important roles in

early telephone exchanges and also in detecting telegraphic distortion. The sensitivity of

these relays are very easy to adjust as the armature of the relay is placed between the poles

of a permanent magnet.



4. Buchholz Relay

This relay is actually used as a safety device. They are used for knowing the

amount of gas present in large oil-filled transformers. They are designed in such a way

that they produce a warning if it senses either the slow production of gas or fast

production of gas in the transformer oil.

5. Overload protection Relay

As the name implies, these relays are used to prevent the electric motors from

damage by over current and short circuits. For this the heating element is kept in series

with the motor. Thus when over heat occurs the bi-metallic strip connected to the motor

heats up and in turn releases a spring to operate the contacts of the relay.

6. Mercury Wetted Relay

This relay is almost similar to the reed relay explained earlier. The only difference

is that instead of inert gases, the contacts are wetted with mercury. This makes them more

position sensitive and also expensive. They have to be vertically mounted for any

operation. They have very low contact resistance and so can be used for timing

applications..

7. Machine Tool Relay

They are mainly used for the controlling of all kinds of machines. They have a

number of contacts with easily replaceable coils. This enables them to be easily converted

from NO contact to NC contact. Many types of these relays can easily be setup in a

control panel. Though they are very useful in industrial applications, the invention of PLC

has made them farther away from industries.

8. Contactor Relay

This is one of the most heavy load relay ever used. They are mainly used in

switching electric motors. They have a wide range of current ratings from a few amps to

hundreds. The contacts of these relays are usually made with alloys containing a small

percentage of silver. This is done so as to avoid the hazardous effects of arcing. These

type of relays are mainly categorized in the rough use areas. So, they produce loud noises

while operated and hence cannot be used in places where noise is a problem.



9. Solid State relay

SSR relays, as its name implies are designed with the help of solid state

components. As they do not have any moving objects in their design they are known for

their high reliability.

10. Solid State Contactor Relay

These relays combine both the features of solid state relays and contactor relays.

As a result they have a number of advantages. They have a very good heat sink and can be

designed for the correct on-off cycles. They are mainly controlled with the help of PLC,

micro-processors or microcontrollers.

4.2. SELECTION OF MOTOR DRIVE SYSTEM

The selection criteria of electrical motors depend on the cost and compatibility at

which the motors work. In this project the induction motor is chosen, as the AC motors are

more advantageous than DC motors. The comparison of electrical motors and drawbacks

with DC motors .The most common and simple industrial motor is the three phase AC

induction motor. The various aspects at which the three phase AC induction motor was

selected is also listed.

DC MOTORS AC MOTORS

The commutator and brushes makes the motor

bulky, costly and heavy

Not bulky and heavy

Costly Expensive

It requires frequent maintenance Less maintenance

Requires battery or inverter They can be used in all locations, as

the supply is AC

Table 1: Comparison between AC Motors and DC Motors

Thus the three phase induction motor is:

• Self-starting.

• Less armature reaction and brush sparking because of the absence of commutators and

brushes that may cause sparks.



• Robust in construction.

• Economical.

• Easier to maintain.

According to Faraday’s law an emf induced in any circuit is due to the rate of

change of magnetic flux linkage through the circuit. As the rotor winding in an induction

motor are either closed through an external resistance or directly shorted by end ring, and

cut the stator rotating magnetic field, an emf is induced in the rotor copper bar and due to

this emf a current flows through the rotor conductor. The relative velocity between the

rotating flux and static rotor conductor is the cause of current generation; hence as per

Lenz’s law the rotor will rotate in the same direction to reduce the cause i.e. the relative

velocity.

From the working principle of three phase induction motor it may observed

that the rotor speed should not reach the synchronous speed produced by the stator. If the

speeds equals, there would be no such relative velocity, so no emf induction in the rotor,

& no current would be flowing, and therefore no torque would be generated. Consequently

the rotor cannot reach at the synchronous speed. The difference between the stator

(synchronous speed) and rotor speeds is called the slip. The rotation of the magnetic field

in an induction motor has the advantage that no electrical connections need to be made to

the rotor.


http://www.electrical4u.com/induction-motor-types-of-induction-motor/

http://www.electrical4u.com/what-is-magnetic-field/

http://www.electrical4u.com/electric-current-and-theory-of-electricity/

http://www.electrical4u.com/lenz-law-of-electromagnetic-induction/



http://www.electrical4u.com/what-is-magnetic-field/

http://www.electrical4u.com/electrical-resistance-and-laws-of-resistance/



http://www.electrical4u.com/what-is-magnetic-field/#Magnetic-Flux-or-Magnetic-Lines-of-Force

http://www.electrical4u.com/faraday-law-of-electromagnetic-induction/


CHAPTER - V

WORKING OF PROJECT

The deficiency of water in the field is sensed by the op-amp based sensor.

Whenever there is need of water in the particular field, the high signal(„1‟) appears on the

output pin of the sensor of that particular field. The output pins of all the sensors are

connected to the PORT 2 of microcontroller. The high signs(logic 1) from the sensor are

entertained by the microcontroller at a particular pin. By knowing the position of the pin

on which signal appears , the microcontroller rotates the water funnel type cup at the

desired angle (i.e. 90 ,180 ,270) by using stepper motor connected at PORT 0 in clockwise

direction. & switch ON the RELAY (i.e. Water pump) connected at port 0. Now water

starts flowing into the required field . after completion of watering the sensor sends low

signal (logic 0) to microcontroller. When uc receives this signal , it switches OFF the

water pump & rotates the stepper motor in anticlockwise direction to the previous angle to

bring the funnel cup in its initial position . now uc starts sensing the signal at PORT 2.

Whenever there is signal at any pin the uc repeats the above process. So this process

continues & we get the automatic irrigation the fields by using intelligent device uc 8051.

5.1. SYSTEM PRINCIPLE

The principles of solar powered intelligent drip irrigation system is based on

control module with sensor data availability to the irrigation system on the difference of

threshold limit of soil moisture content of the irrigated crops, and real-time soil moisture

content. When the soil moisture content of the crop is below the permissible limit, the

sensors will message to control system and irrigation system to start the irrigation until the

soil moisture content reaches the desired limit.

5.2 SYSTEM DESCRIPTION

Proposed irrigation system mainly consists of two modules- Solar pumping modul

and automatic irrigation module. In solar pumping module a solar panel of required

specification is mounted near the pump set.



Fig. 7: Block diagram of solar pumping module.

Then using a control circuit it is used to charge a battery. From the battery using a

Converter circuit it gives power to the water pump which is submerged inside the well.

Then the water is pumped into an overhead tank for storing water temporarily before

releasing the water into the field. In automatic irrigation module the water outlet valve of

the tank is electronically controlled by a soil moisture sensing circuit. The sensor is placed

in the field where the crop is being cultivated. The sensor converts the moisture content in

the soil into equivalent voltage. This is given to a sensing circuit which has a reference

voltage that can be adjusted by the farmer for setting different moisture levels for different

crops.

The amount of water needed for soil is proportional to the difference of these two

voltages. A control signal was given to a stepper motor whose rotational angle is

proportional to the difference in voltage. The stepper motor in turns controls the

crosssectional area of the valve to be opened controlling flow of water. Therefore the

amount of water flowing is proportional to the moisture difference.



Fig. 8: Block diagram of automatic irrigation module.

5.3 COST ANALYSIS

With over nine hundred thousand tube wells being used in every state of India,

around Rs.18 Million of energy is used for pumping water for irrigation. This amount of

money used for Electricity can be saved with the help of solar water pump. Annually the

cost of nearly five million kilo watt hour of energy can be spared. That is around Rs.27

Million per annum can be redeemed which comes around 40% of the total amount of

investment. Even though the initial investment is high, it can be earned back in 2 and a

half years’ time. If we assume the cost of power is Rs. 1.5 Million per kilo watt hour,

Rs.18 Million is used for pumping water alone in a year. By using the solar water pump,

we can save up to 4.8 million KWh of energy annually which saves a lot of energy. The

excess energy can also be given to the grid with small modifications and investments in

the circuit, which can add to the revenue of the farmer.

Cost analysis

Component Unit Cost Quantity Total Cost

Solar Panel (1.4m2) 24000 4 Rs.96000

Converter Circuit 400 1 Rs.400

Battery 24V,100Ah 8250 1 Rs.8250

Overall cost Rs.104650

Table2: Cost analysis


Water Pump Irrigation Field

Moisture Sensor Actuator


ADVANTAGES

An advantage of using direct solar radiation as a power source for irrigation is that

it is available at the site of application without the employment of a distribution system

• It helps in saving Energy.

• There is no fuel cost - as it uses available free sun light.

• No electricity required.

• Can be operated lifelong.

• It is highly reliable and durable.

• Easy to operate and maintain

• It is also useful for clean, drinking water sanitation and also irrigation.

• It reduces the dependence on rain is reduced.

• It creates wealth for farmers by increasing no of crops.



DIS ADVANTAGES

That disadvantage is that the sun doesn’t shine 24 hours a day. When the sun goes

down or is heavily shaded, solar PV panels stop producing electricity. If we need

electricity at that time, we have to get it from some other source.

In other words, we couldn’t be 100% powered by solar panels. At the very least,

we need batteries to store electricity produced by solar panels for use sometime

later.

However, there are a couple of key things to note regarding this solar power

disadvantage. Firstly, the sun actually does shine when we need electricity most.

As humans (not vampires), our days more or less follow the movement of the sun.

Society more or less wakes up when the sun rises.

At the time of the sun’s greatest height and visibility, humans tend to be most

active. At this time, we are of course using much more electricity than in the

middle of the night, so electricity is in greater demand. (This also makes electricity

more expensive in the middle of the day, making electricity produced from solar

panels more valuable.



APPLICATIONS

Solving needs of rural population.

Town and City Water Supply

Livestock Watering

Irrigation


http://blog.ennovent.com/2012/03/solar-powered-irrigation-pumps-solving-needs-of-rural-population/


CONCLUSION

This paper managed to stumble upon the fact that the largest advantage of solar

energy is its attribute as being free and unlimited source of energy. We have also found

out that the research of the development of solar irrigation system requires vast knowledge

and familiarity about renewable energy, as well as other parameters of control. The

parameters of the system that have been used in the project are soil moisture sensor, light

detecting sensor and level sensors. The design of SCADA system is meant for adding an

operator on automatic irrigation system. Through SCADA system, the operator can read

and write data from the controller (PLC) in addition to this there is a report of the system

in excels form and that can be printed. After continuous work and effort, it was

manageable to test the system by making it function properly. This project is very vital for

all systems that deal with liquid monitoring and controlling specially in the irrigation

field . The SCADA system helps administrators to control an d monitor irrigation system.

As stated, the project can be expanded to oil and gas monitoring system and greenhouse

implementation system. Based on the result obtained from measurement, the system

performance is quite reliable and accurate. The system has successfully overcome quite a

few failings of the existing system by reducing the power consumption, maintenance and

automatic system interface with SCADA system.



REFERENCES

[1] Harris 2009 Solar Powered Automated Greenhouse Irrigation System (LumiTech

International Limited)

[2] Morris And Lynne 2008 Solar-Powered Livestock Watering Systems (ATTRA)

[3] B.L.S. Lui 2006 Trial Use of Solar Power Automatic Irrigation System 7-11

[4] Noko And Road 2005 Solar International Botswana (Pty) Ltd. (InWEnt)

[5] B. Eker 2005 Solar Powered Water Pumping Systems 3 7-11

[6] Vick And Almas 2008 Developing Wind And/ Or Solar Powered Crop Irrigation

Systems For The Great Plains 27 235-245

[7] Helikson ,Haman And Baird 2009 Pumping Water For Irrigation Using Solar Energy

(Florida Energy Extension Service)


automatic solar irrigation pump control system based on soil moisture sensor (1).doc

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single solar module

project soil moisture

soil moisture content

irrigation pump motor

solar panels available

soil moisture sensor

use of soil moisture

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