1. INTRODUCTION Energy is a requirement that is endlessly and exhaustingly utilized the world over. With the increase in the rate of various developmental activities around the world the energy being consumed is also increasing with the result that conventional energy resources are fast getting depleted and even hydel reserves are proving less than sufficient to satisfy the growing energy demand. As a result consumers around the world have to bear the brunt of increasing power cuts and power costs. Hence for the future power independence is fast becoming a vital requirement. The concept design therefore formulates a system which provides internally generated energy for homes and also integrates a sub system into the household such that the dependence on the electricity board is eliminated.
HYBRID GENERATING UNIT The generating unit for the proposed design utilizes a hybrid power source as a means of powering the household loads. The hybrid power source combines wind and solar energy to service the household requirements. Hybrid system for home is a combined system of wind and solar power generation system. Aero turbines convert wind energy into rotary mechanical energy. A mechanical interface, consisting of a step-up gear and a suitable coupling transmits the energy to an electrical generator. The output of this generator is connected to the Battery or system grid. The battery is connected to 1
the inverter. The inverter is used to convert DC voltages to AC voltages. The load draws current from the inverter. The apparatus involved for the windmill section are:
Generator
Main shaft with Leafs
Gear Wheel Arrangement
Wind power ratings can be divided into three convenient grouping, small to 1kW, medium to 50 kW and large 200 kW to megawatt frame size. Solar energy implies the energy that reaches the earth from the sun. It provides daylight makes the earth hot and is the source of energy for plants to grow. Solar energy is also put to two types of use to help our lives directly solar heating and solar electricity Solar electricity is the technology of converting sunlight directly in to electricity. It is based on photo-voltaic or solar modules, which are very reliable and do not require any fuel or servicing. Solar electric systems are suitable for plenty of sun and are ideal when there is no main electricity
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1.1
HYBRID SYSTEM BLOCK DIAGRAM
MULTI-BLADE (LEAF)
GENERATOR SHAFT
INVERTER
LIGHTING LOAD (OR) GRID
BATTERY
SOLAR PANEL
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1.2 CONTROL CENTRE The control centre has been designed integrated within the household. The entire system shall be wireless based. However against contemporary systems already in the market, the proposed design shall be based on an Wi-Fi network which shall be circulated by a laptop or system based transponder. Thus the designed control centre shall have the advantages of being wire free as well as based upon an easily available apparatus, that is a laptop or a system which can be found in most households. The design is aimed at replicating all functions performed by a normal energy control centre: Each room supply control Shutdown, start ,restart control Dimmer control Breaking control All the above systems shall be integrated to develop a power efficient system for the future.
2. HYBRID GENERATING STATION
Hybrid system for home is a combined system of wind and solar power generation system. Aero turbines convert wind energy into rotary mechanical energy.
A mechanical interface, consisting of a step-up gear and a suitable 4
coupling transmits the energy to an electrical generator.
The output of this
generator is connected to the Battery or system grid. The battery is connected to the inverter. The inverter is used to convert DC voltages to AC voltages. The load is drawn current from the inverter.
Generator, Main shaft with Leafs, Gear Wheel Arrangement Wind power ratings can be divided into three convenient grouping, small to 1kW, medium to 50 kW and large 200 kW to megawatt frame size. Solar energy means all the energy that reaches the earth from the sun. It provides daylight makes the earth hot and is the source of energy for plants to grow. Solar energy is also put to two types of use to help our lives directly solar heating and solar electricity. Solar electricity is the technology of converting sunlight directly in to electricity. It is based on photo-voltaic or solar modules, which are very reliable and do not require any fuel or servicing. Solar electric systems are suitable for plenty of sun and are ideal when there is no main electricity.
2.1 WIND ENERGY INTRODUCTION Wind result from air in motion. Air in motion arises from a pressure gradient. On a global basis one primary forcing function causing surface winds 5
from the poles toward the equator is convective circulation. Solar radiation heats the air near the equator, and this low density heated air is buoyed up. At the surface it is displaced by cooler more dense higher pressure air flowing from the poles. In the upper atmosphere near the equator the air thus tend to flow back toward the poles and away from the equator. The net result is a global convective circulation with surface wins from north to south in the northern hemisphere. It is clear from the above over simplified model that the wind is basically caused by the solar energy irradiating the earth. This is why wind utilization is considered a part of solar technology. It actuality the wind is much more complex. The above model ignores the earth’s rotation which causes a coriolis force resulting in an easterly wind velocity component in the northern hemisphere. There is the further complication of boundary layer frictional effects between the moving air and the earth’s rough surface. Mountains, trees, buildings, and similar obstructions impair stream line air flow. Turbulence results and the wind velocity in a horizontal direction markedly increase with altitude near the surface. Local winds are caused by two mechanisms. The first is differential hating of land and water. Solar isolation during the day is readily converted to sensible energy of the land surface but is partly absorbed in layers below the water surface and partly consume in evaporating some of that water. The land mass becomes
hotter than the water, which causes the air above the land to heat up and become warmer than the air above water. The warmer lighter air above the land rises and the cooler heavier air above the water moves into replace it. This is the mechanism 6
of shore breezes. At night, the direction of the breezes is reversed because the land mass cools to the sky more rapidly than the water, assuming a sky. The second mechanism of local winds is caused by hills and mountain sides. The air above the slopes heats up during the day and cools down at night, more rapidly than the air above the low lands. This causes heated air the day to rise along the slopes and relatively cool heavy air to flow down at night. Wind turbines produce rotational motion; wind energy is readily converted into electrical energy by connecting the turbine to an electric generator. The combination of wind turbine and generator is some times referred as an aero generator. A step-up transmission is usually required to match the relatively slow speed of the wind rotor to the higher speed of an electric generator. In India the interest in the windmills was shown in the last fifties and early sixties.
A part from importing a few from outside, new designs was also
developed, but it was not sustained. It is only in the last few years that development work is going on in many institutions. An important reason for this lack of interest in wind energy must be that wind, in India area relatively low and vary appreciably with the seasons. Data quoted by some scientists that for India wind speed value lies between 5 km/hr to 15-20 km/hr. These low and seasonal winds imply a high cost of exploitation of wind energy. Calculations based on the performance of a typical windmill have indicated that a unit of energy derived from a windmill will be at least several times more expensive than energy
derivable from electric distribution lines at the standard rates, provided such electrical energy is at all available at the windmill site. 7
The above argument is not fully applicable in rural areas for several reasons. First electric power is not and will not be available in many such areas due to the high cost of generation and distribution to small dispersed users. Secondly there is possibility of reducing the cost of the windmills by suitable design. Lastly, on small scales, the total first cost for serving a felt need and low maintenance costs are more important than the unit cost of energy. The last point is illustrated easily: dry cells provide energy at the astronomical cost of about Rs.300 per kWh and yet they are in common use in both rural and urban areas.Wind energy offers another source for pumping as well as electric power generation. India has potential of over 20,000 MW for power generation and ranks as one of the promising countries for tapping this source. The cost of power generation from wind farms has now become lower than diesel power and comparable to thermal power in several areas of our country especially near the coasts. Wind power projects of aggregate capacity of 8 MW including 7 wind farms projects of capacity 6.85 MW have been established in different parts of the country of which 3 MW capacity has been completed in 1989 by DNES. Wind farms are operating successfully and have already fed over 150 lakes units of electricity to the respective state grids. Over 25 MW of additional power capacity from wind is under implementation. Under demonstration programmer 271 wind pumps have been installed up to February 1989. Sixty small wind battery charges of capacities 300 watts to 4 kW are under installation. Likewise to stand-alone wind electric generators of 10 to 25 kW are under installation.
2.2 CONVERSION PRINCIPLES BLOCK DIAGRAM 8
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2.3 The Nature of the Wind
The circulation of air in the atmosphere is caused by the non-uniform heating of the earth’s surface by the sun. The air immediately above a warm area expands; it is forced upwards by cool, denser air which flows in from surrounding areas causing a wind. The nature of the terrain, the degree of cloud cover and the angle of the sun in the sky are all factors which influence this process. In general, during the day the air above the land mass tends to heat up more rapidly than the air over water. In coastal regions this manifests itself in a strong onshore wind. At night the process is reversed because the air cools down more rapidly over the land and the breeze therefore blows off shore.
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The main planetary winds are caused in much the same way: Cool surface air sweeps down from the poles forcing the warm air over the topics to rise. But the direction of these massive air movements is affected by the rotation of the earth and the net pressure areas in the countries-clockwise circulation of air around low pressure areas in the northern hemisphere, and clockwise circulation in the southern hemisphere. The strength and direction of these planetary winds change with the seasons as the solar input varies. Despite the wind’s intermittent nature, wind patterns at any particular site remains remarkably constant year by year. Average wind speeds are greater in hilly and coastal areas than they are well inland. The winds also tend to blow more consistently and with greater strength over the surface of the water where there is a less surface drag. Wind speeds increase with height. They have traditionally been measured at a standard height of ten meters where they are found to be 20-25% greater than close to the surface. At a height of 60 m they may be 30-60% higher because of the reduction in the drag effect of the earth’s surface.
2.4 WIND POWER
The power in the wind can be computed by using the concept of kinetics. The wind will works on the principle of converting kinetic energy of the wind to mechanical energy. We know that power is equal to energy per unit time. The energy available is the kinetic energy of the wind. The kinetic energy of any
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particle is equal to one half it’s mass times the square of its velocity, or 1/2m V 2. The amount of air passing in unit time, through an area A, with velocity V, is AV, and its mass m is equal to its volume multiplied by its density of air, or m=AV (m is the mass of air transverse the area A swept by the rotating blades of a wind mill type generator). Substituting this value of the mass in the expression for the kinetic energy, we obtain, kinetic energy = 1./2 AV.V2 watts. =1/2 AV3 watts Equation tells us that the maximum wind available the actual amount will be somewhat less because all the available energy is not extractable-is proportional to the cube of the wind speed. It is thus evident that small increase in wind speed can have a marked effect on the power in the wind. Equation also tells us that the power available is proportional to air density 1.225 kg/m3 at sea level). It may vary 10-15 percent during the year because of pressure and temperature change.
It changes negligibly with water content.
Equation also tells us that the wind power is proportional to the intercept area. Thus an aero turbine with a large swept area has higher power than a smaller area machine; but there are added implications. Since the area is normally circular of diameter D in horizontal axis aero turbines, then A = /4 D2, (sq.m), which when put in equation gives, Available wind power P= ½ /4 D2V3 watts = 1/8 D2V3 12
2.5 PRESSURE AND VELOCITY GRAPH
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The power extracted by the rotor is equal to the product of the wind speed as it passes through the rotor (i.e. Vr) and the pressure drop p. in order to maximize the rotor power it would therefore be desirable to have both wind sped and pressure drop as large as possible. However, as V is increased for a given value of the free wind speed (and air density), increases at first, passes through a maximum, and the decreases. Hence for the specified free-wind speed, there is a maximum value of the rotor power. The faction of the free-flow wind power that can be extracted by a rotor is called the power-coefficient; thus Power of wind rotor Power coefficient = Power available in the wind
Where power available is calculated from the air density, rotor diameter, and free wind speed as shown above. The maximum theoretical power coefficient is equal to 16/27 or 0.593. This value cannot be exceeded by a rotor in a free-flow wind-stream.
2.6 Maximum Power The total power cannot be converted to mechanical power. Consider a horizontal-axis, propeller-type windmill, henceforth to be called a wind turbine, which is the most common type used today. Assume that the wheel of such a turbine has thickness b. Let pi and Vi
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are the wind pressure and velocity at the upstream of the turbine. V e is less than Vi because the turbine extracts kinetic energy. Considering the incoming air between I and a as a thermodynamic system, and assuming that the air density remains constant (since changes in pressure and temperature are very small compared to ambient), that the potential energy is zero, and no heat or work are added or removed between i and a, the general energy equation reduces to the kinetic and flow energy-terms only:
2.7 Wind Energy Conversion Traditional windmills were used extensively in the Middle Ages to mill grain and lift water for land drainage and watering cattle. Wind energy converters are still used for these purposes today in some parts of the world, but the main focus of attention now lies with their use to generate electricity. There is also growing interest in generating heat from the wind for space and water heating and for glasshouses but the potential market is much smaller than for electricity generation. The term “wind mill” is still widely used to describe wind energy conversion systems, however it is hardly adopt. Description any more. Modern wind energy conversion systems are more correctly referred to as ‘WECS’, aero generations’, ‘wind turbine generators’, or simply ‘wind turbines’. The fact that the wind is variable and intermittent source of energy is immaterial of some applications such as pumping water for land drainage – provided, of course, that there is a broad match between the energy supplied over any critical period and the energy required. If the wind blows, the job gets done; if it does not, the job waits.
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However, for many of the uses to which electricity is put, the interruption of supply may be highly inconvenient. Operators or users of wind turbines must ensure that there is some form of back-up to cover periods when there is insufficient (or too much) wind available. For small producers, back-up can take the form of: (i)
Battery storage,
(ii)
Connection with the local electricity distribution system; or
For utilities responsible for public supply, the integration of medium – sized and large wind turbines into their distribution net work could require some additional plant which is capable of responding quickly to meet fluctuating demand.
2.8 Turbine Tower System
As stated earlier, the horizontal axis wind turbines are mounted on towers, and there are wind forces on the tower. Both upwind and downwind locations have been used so that tower design is an essential aspect of the overall system design.
Vertical-Axis Machines Vertical – axis rotors can be either drag-or lift-based. The cup anemometer is an example of a drag-based, vertical axis wind device. The drag on a cup is greater when its concave side faces the wind which causes the device to rotate. Lift also plays a small part: the cups crossing the wind experience a small lift because their convex surfaces deflect the wind and causes a pressure reduction. 17
The main virtue of the cup anemometer is that it tends to rotate within a narrow range of TSRS under all conditions, so its rotational speed is closely proportional to wind speed. However, it can not carry a load with any efficiency; it has never been constructed on a large scale for use as a wind turbine. The Savonius rotor works on a principle similar to that of the cup anemometer but is adopted to produce shaft power. It also takes advantage of the lift generated as the curved outer surfaces of its scoops cross the air flow. There are also a variety of so-called Panamones; there are pure drag devices, in which one side of the rotor carries blades or sails square to the wind, while other side produces reducing drag by shielding or furling the blades. Because drag devices tend to run at TSR below unity (since their tips can not readily travel faster than the wind), they are inevitably less efficient than lift-dependent devices. In addition, their high solidity makes them more material-intensive in relation to the wind area ‘seen’ by the rotor. Hence following are the three distinct advantages of vertical axis wind turbines over horizontal axis ones: (1)
They will react to wind from any direction and therefore do not need yawing equipment to turn the rotor into the wind.
(2)
They can require less structural support because heavy components (like gear box and generator) can be located at ground level.
This
configuration also eases installation and maintenance. (3)
Since the blades do not turn end over end, the rotor is not subjected to continuous cyclic gravity loads. (Fatigue induced by such action is a major consideration in the design of large horizontal axis machines).
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Properly the single biggest disadvantage with vertical axis machines is that far less is known about them than horizontal axis ones. This handicap is rapidly being removed.
Advantages of such WEC system are:
1.
The major advantage of this design is that the rotor blades can accept the wind from any compass.
2.
Another added advantage is that the machine can be mounted on the ground eliminating tower structures and lifting of huge weight of machine assembly, i.e. it can be operated close to the ground level.
3.
Since this machine has vertical axis symmetry, it eliminates yaw control requirement for is rotor to capture wind energy. A dual purpose and relatively simple shaft axis support is anticipated as well as ground level power output delivery due to presence of vertical shaft. This may in turn, allow easier access and serviceability.
4.
Airfoil rotor fabrication costs are expected to be reduced over conventional rotor blade costs.
5.
The absence of pitch control requirements are synchronous operation may yield additional cost savings.
6.
The tip speed ratio and power coefficient are considerably better than those of the S-rotor but are still below the values for a modern horizontalaxis, two-bladed propeller rotor.
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Disadvantages
(1) Although a Darrieus machine has many directional symmetry for wind energy capture, it require external mechanical aid for start up. Tests indicate that, with small machines, the problem can be solved by attaching S-rotors at the top and bottom of the vertical (rotational) axis. This approach does not appear to be feasible with larger machines, but if the wind power system connected to a utility grid, the generator can serve as a motor to start the turbine. The (alternatingcurrent) load can also provide a means for controlling the speed of the rotor regardless of the wind speed, so that variable-pitch blades are not required. At very high speeds, stalling occurs and the rotation stops automatically. (2) Rotor power output efficiency of a Darrieus wind energy conversion system is also somewhat lower than that of a conventional horizontal rotor. (3) Because a Darrieus rotor is generally situated near ground proximity, it may also experience lower velocity wind compared to a tower mounted conventional wind energy conversion system of comparable projected rotor disc area. This may yield less energy output. (4) Because a Darrieus rotor encounters greatly varied local flow conditions per revolution, greater vibratory stresses are encountered which will affect rotor system life? High tension cable it down of tower-shaft may require large extensive bearing for support. (5) Finally since a Darrieus rotor cannot be yawed out of the wind or its blades feathered, special high torque braking system must be incorporated.
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TABLE 1:WINDMILL SPECIFICATION TABLE
2.9.SOLAR ENERGY UTILIZATION 2.9.1 DIRECT METHOD 2.9.1.1 Photo Voltaic Method 2.9.1.2 Thermal Method
2.9.1 DIRECT METHOD OF UTILIZATION OF SOLAR ENERGY:
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The most useful way of harnessing solar energy is by directly converting it into electricity by means of solar photo-voltaic cells. Sunshine is incident on Solar cells, in this system of energy Conversion that is direct conversion of solar radiation into electricity. In the stage of conversion into thermodynamic from is absent. The photo-voltaic effect is defined as the generation of an electromotive force as a result of the absorption of ionizing radiation.
Energy conversion
devices, which are used to convert sunlight to electricity by use of the photovoltaic effect, are called solar cells. In recent years photo-voltaic power generation has been receiving considerable attention as one of the more promising energy alternatives. The reason for this rising interest lie in PV’s direct conversion of sunlight to electricity, the non polluting nature of the PV widespread are of PV generation has been hampered by economic factors. Here to force, the low cost of conventional energy sunlight has obviated the development of a broad-based PV technology. At the present time, PV generation can be justified only for special situations mostly for remote sites where utility lines on other conventional means of furnishing energy may be prohibitively expensive and is one of the most attractive non-conventional energy sources of proven reliability from the micro to the Mega-watt level. Like other energy system this system also has some disadvantages (1)
Distributed nature of solar energy,
(2)
Absence of energy storage,
(3)
Relatively high capital cost.
2.9.2 PHOTOVOLTAIC PRINCIPLES: The photo-voltaic effect can be observed in nature in a variety of materials that have shown that the best performance in sunlight is the semiconductors as 22
stated above. When photons from the sun are absorbed in a semiconductor, that create free electrons with higher energies than the created there must be an electric field to induce these higher energy electrons to flow out of the semi-conductor to do useful work. A junction of materials, which have different electrical properties, provides the electric field in most solar cells.
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FIG.1
24
FIG.2
FIG.3
25
26
FIG.4
To obtain a useful power output from photon interaction in a semiconductor, three processes are required. 1)
The photon has to be absorbed in the active part of the material and result in electrons being excited to a higher energy potential.
2)
The electron hole charge carriers created by the absorption must be physically separated and moved to the edge of the cell.
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3)
The charge carriers must be removed from the cell and delivered to useful load before they loose extra potential.
For completing the above processes a solar cell consists of:(a)
Semi-conductor in which electron hole pairs are created by absorption of incident solar radiation.
(b)
Region containing a drift field for charge separation
(c)
Charge collecting fronts and back electrodes.
The photo-voltaic effect can be described easily for p-n junction in a semiconductor. In an intrinsic semi-conductor such as silicon, each one of the four valence electrons of the material atom is tied in a chemical bond, and there are no free electrons at absolute zero. If a piece of such a material is doped on one side by a five valance electron material, such as arsenic or phosphorus, there will be an excess of electrons in that side, becoming an n-type semi-conductor. The excess electrons will be practically free to move in the semi-conductor lattice. When a three valence electron material, such as boron dopes the other side of the same piece, there will be deficiency of electrons leading to a p-type semiconductor. This deficiency is expressed in terms of excess of holes free to move in the lattice. Such a piece of semi-conductor with one side of the p-type and the other, of the n-type is called p-n junction. In this junction after the protons are absorbed, the free electrons of the n-side will tends to flow to the p-side, and the holes of the p-side will tend to flow to the n-region to compensate for their respective deficiencies. This diffusion will create an electric field from the nregion to the p-region. This field will increase until it reaches equilibrium for V, the sum of the diffusion potentials for holes and electrons. 28
3. COMMISSIONING The panel is mounted over the top the pole with a help of a clamp at an angular distance 11º south of equator, so it is able to collect the solar energy at the maximum level then the frame with light is mounted at a height of 125º from the pole. Then a metal box with the LDR control and a charge controller and with the 24V battery is mounted over the pole, at a height of 2m from the ground level.
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The connections are made as per, first the panel is connected to charge controller and then to the battery and to an inverter, then the connection is given to the light with LDR control. 3.1 POLE DATA: Galvanized steel pole Pole diameter =
10cm
Height
=
Thickness of the pole
5.5m =
3mm
3.2 CONCRETE: Cement Sand Aggregate (40mm size) Cement, sand and aggregate ratio Water cement ratio =
=
2:4:8
0.5
Then a trench of 1 = b = h = 1.5m is made and the cement mixture made is filled upto 1.5m in the trench and the pole is mounted inside the trench upto 1.5m from the ground level. The pole is mounted inside the trench and the trench is filled with the cement mixture and made to set. And brickwork is done above the ground level of 1.5m with 1:3 ratio and plastered with 1:4 ratio of cement and sand. 30
3.3 SOLAR PANEL COMMISSIONING: During the day time the battery gets charged and when the intensity of light decreases, the LDR makes the light to gets ON and the light glows by using the stored charge in the battery. If electrical contacts are made with the two semiconductor materials and the contacts the connected through an external electrical conductor, the free electrons will flow from the n-type material through the conductor to the p-type material (figure 2). Here the free electrons will enter the holes and holes and become bound electrons thus both free electrons and hole will be removed. The flow of electrons through the external conductor constitutes an electric current, which will continue as long as move free electrons and holes are being formed by the solar radiation. This is the basis of photo-voltaic conversion that is the conversion of solar energy into electrical energy. The combination of n-type and p-type semiconductors thus constitutes a photo-voltaic cell or solar cell. All such cells some rate direct current that can be converted into alternating current it desired. The photo-voltaic effect can be observed in almost any junction of material that have different electrical characteristics, but the best performance to date has been from cells using semiconductor materials especially all of the solar cells used for both space and terrestrial applications have been made of the semiconductor silicon. Future cells may use such materials as the Semiconductors like Gallium arsenate, copper sulphate cadsulphide etc.
3.4 Safety Systems Safety systems of the wind turbines comprise the following features:
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(i) The computer. The wind turbine is controlled by a computer which monitors the most important gauging instruments and compares the results. If errors are found the wind turbine is stopped. (ii) Emergency stop. If a situation arises which calls for the wind turbine to be stopped immediately, the emergency stop is used. The wind turbine will stop in few seconds by feathering the blades directly into the wind. It can not be stated again before what caused the emergency stop has been rectified. (iii) Revolution Counters. To prevent the rotor from racing, two revolution counters have been mounted on the shaft. These operates quiet independently and activate the emergency stop if the revolutions of the turbine exceed 24 rpm which is maximum. (iv) Wind Velocity. This is measured and controlled by the computer in two ways. First gusts of wind are registered and if they are too strong the turbine is stopped. Then average wind speeds are measured over periods of 10 minutes, and the wind turbine is also stopped if there are too high. (v) The Parachutes. Each blade tip has a parachute, which is activated if the rpm exceeds 28. An iron plumb bob, otherwise held in place by a magnet, is released from the blade trip, the centrifugal force exceeding the force of the magnet pulling out the parachute. This decrease the speed of the wind turbine considerable enough to stop it from racing. The parachute is an extra safety device should other fail. Till now they never had been used. (Vi) Lightning Rods. The tree blades and the mill or wind turbine cap are protected from lighting by these rods going from the tip of each blade to the ground.
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3.5 Environmental Aspects Wind turbines are not without environmental impact and their operation is not entirely risk-free. Following are the main effects due to a wind turbine. (i) Electromagnetic interference. Interference with TV and other electromagnetic communication systems is a possibility with wind turbines as it is with other tall structures. TV interference is most likely in areas where there is a weak signal because of the distance from the transmitter, where existing reception is none too good due to the surrounding hills and where the wind turbine is exposed in good position to receive and scatter the signals. Dispensing with aerials and sending TV signals by cable in areas that would otherwise be affected can overcome interference. (ii) Noise. The noise produced by wind farms falls into two categories. The first type is a mechanical noise from the gearbox, generating equipment and linkages and the second type of aerodynamic in nature produced by the movement of the turbine blades. One component of the latter is the broad band noise which ranges upto several kilo hertz and the other is a low frequency noise of 15-20 Hz. Revolving blades generate noise which can be heard in the immediate vicinity of the installation, but noise does not travel too far.
(iii) Visual Effects.
Megawatts power generating wind turbines are massive
structures which would be quite visible over a wide area in some locations. Variety characteristics such as co lour pattern, shape, rotational speed and reflectance of blade materials can be adjusted to modify the visual effects of wind turbines including the land scape in which they are installed.
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4. CONTROL CENTRE The Energy Control Centre (ECC) is the constituent of the electricity board which maintains and regulates all aspects of energy distribution to a specified area of charge. To implement a household power system which is completely independent of the electricity board a control scheme has been 34
designed which replicates the features of a regular control centre and implements it as per the requirements of the household. For the operational programming of the control centre a energy utilization analysis centred upon the household in question is utilized. Corresponding to the requirements of power at various times in a day and the general patterns of load variations observed the prime control system, wireless control MODEM can be programmed for controls extending to the following: ON/OFF Control Load Shedding Controls Appliance Specific Control Monitoring Controls The system during implementation is in all likelihood to be utilized by an average common person. Hence to make the system understandable and easy to use, all controls have been conceptualized in the form of GUI’s or Graphical User Interfaces. As such by simple visual supervision with a few control keysets the entire power system could be controlled.
FIG.5: IMPLEMENTATION OVERVIEW
35
HAN MODEM
4.1 DESIGNED CONTROL GUI’s 36
MANUAL
4.2.1 MONITOR GUI 37
ROOM 1:
ROOM 2:
ROOM 3:
ROOM 4:
4.2.2 GENERATION MONITOR GUI 38
S H U T DOWN
4.3 CONTROL CENTRE PRINCIPLE The control centre is based around a system or laptop for providing a human machine interface and a wireless control MODEM to provide for the 39
control interface. Based on a Home Area Network the MODEM could be utilized alongwith pre-fed programming modules to actuate the control and monitor functions. The network is a home network which can be created with the laptop or the system acting as the central transponder. The MODEM is plugged in via a USB port. Interfacing with individual transponders it extracts the input data for actuating control as per the pre written programs. The MODEM in use can be a GPS network MODEM or a GSM MODEM, depending upon the controlling network being used. Under the current implementation of the project since an internal network is being utilized, a GSM MODEM suffices for the actuation of control.
4.4 G.S.M 4.4.1 GSM INTRODUCTION (Global System for Mobile communications: originally from Groupe Spécial Mobile) is the most popular standard for mobile phones in the world. Its most explicit implementation is seen in mobile communication alone. However the GSM network protocol can be applied to power systems too subject to some modifications in its end usage. GSM is a cellular network, which means that mobile phones connect to it by searching for cells in the immediate vicinity. GSM networks operate in four different frequency ranges. Most GSM networks operate in the 900 MHz or 1800 MHz bands. There are five different cell sizes in a GSM network—macro, micro, pico, femto and umbrella cells. The coverage area of each cell varies according to the implementation environment. Macro cells can be regarded as cells where the base station antenna is installed on a mast or a building above average roof top level. Micro cells are cells whose antenna height is under average roof top level; they are typically used in urban areas. Picocells are small cells whose coverage diameter is a few dozen meters; they are mainly used 40
indoors. Femtocells are cells designed for use in residential or small business environments and connect to the service provider’s network via a broadband internet connection. Umbrella cells are used to cover shadowed regions of smaller cells and fill in gaps in coverage between those cells. Indoor coverage which is the requirement of the particular control structure is supported by GSM and may be achieved by using an indoor picocell base station, or an indoor repeater with distributed indoor antennas fed through power splitters, to deliver the radio signals from an antenna outdoors to the separate indoor distributed antenna system. The modulation used in GSM is Gaussian minimum-shift keying (GMSK), a kind of continuous-phase frequency shift keying. In GMSK, the signal to be modulated onto the carrier is first smoothed with a Gaussian low-pass filter prior to being fed to a frequency modulator, which greatly reduces the interference to neighboring channels (adjacent channel interference).
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4.4.2 STRUCTURE OF GSM NETWORK
42
A common GSM network invariably consists of the following: 43
the Base Station Subsystem (the base stations and their controllers). the Network and Switching Subsystem (the part of the network most similar to a fixed network). This is sometimes also just called the core network. the GPRS Core Network (the optional part which allows packet based Internet connections). The above descriptions pertain to a general overview of GSM. However specific to the project design at hand the same has been modified to replicate the features of power system control centre. For the application of the GSM modem to the area of power system control programming modules have been used along with incorporation of power system equipments.
4.5 PROGRAMMING PLATFORM The programming of the modem is performed relative to a energy utilization datasheet which is drawn out by studying the energy usage pattern observed during any normal operational day. Based on the timing ranges for which maximum power is required, time of use of power in individual sections of the household an operating schedule can be developed based on which the control centre can be programmed.
4.5.1
INTERFACE
PROTOCOLS
:MAX
232
SERIAL
COMMUNICATIONS
Electrical signal characteristics such as voltage levels, signaling rate, timing and slew-rate of signals, voltage withstand level, short-circuit 44
behavior, and maximum load capacitance. Interface mechanical characteristics, pluggable connectors and pin identification. Functions of each circuit in the interface connector. Standard subsets of interface circuits for selected telecom applications. The standard does not define such elements as character encoding (for example, ASCII, Baudot code or EBCDIC) the framing of characters in the data stream (bits per character, start/stop bits, parity) protocols for error detection or algorithms for data compression bit rates for transmission, although the standard says it is intended for bit rates lower than 20,000 bits per second. Many modern devices support speeds of 115,200 bit/s and above
power supply to external
devices. Details of character format and transmission bit rate are controlled by the serial port hardware, often a single integrated circuit called a UART that converts data from parallel to asynchronous start-stop serial form. Details of voltage levels, slew rate, and short-circuit behavior are typically controlled by a line-driver that converts from the UART's logic levels to RS-232 compatible signal levels, and a receiver that converts from RS-232 compatible signal levels to the UART's logic levels. The original DTEs were electromechanical teletypewriters and the original DCEs were (usually) modems. When electronic terminals (smart and dumb) began to be used, they were often designed to be interchangeable with teletypes, and so supported RS-232. The C revision of the standard was issued in 1969 in part to accommodate the electrical characteristics of these devices. Since application to devices such as computers, printers, test instruments, and so on was not considered by the standard, designers implementing an RS-232 compatible interface on their equipment often interpreted the requirements idiosyncratically. Common problems were non-standard pin assignment of circuits on connectors, and incorrect or missing control signals. The lack of adherence to 45
the standards produced a thriving industry of breakout boxes, patch boxes, test equipment, books, and other aids for the connection of disparate equipment. A common deviation from the standard was to drive the signals at a reduced voltage: the standard requires the transmitter to use +12V and -12V, but requires the receiver to distinguish voltages as low as +3V and -3V. Some manufacturers therefore built transmitters that supplied +5V and -5V and labeled them as "RS232 compatible." Later personal computers (and other devices) started to make use of the standard so that they could connect to existing equipment. For many years, an RS-232compatible port was a standard feature for serial communications, such as modem connections, on many computers. It remained in widespread use into the late 1990s. While it has largely been supplanted by other interface standards, such as USB, in computer products, it is still used to connect older designs of peripherals, industrial equipment (such as based on PLCs), and console ports, and special purpose equipment such as a cash drawer for a cash register. Because the application of RS-232 has extended far beyond the original purpose of interconnecting a terminal with a modem, successor standards have been developed to address the limitations. Issues with the RS-232 standard include: The large voltage swings and requirement for positive and negative supplies increases power consumption of the interface and complicates power supply design. The voltage swing requirement also limits the upper speed of a compatible interface.Single-ended signaling referred to a common signal ground limits the noise immunity and transmission distance. Multi-drop connection among more than two devices is not defined. While multi-drop "work-arounds" have been devised, they have limitations in speed and compatibility. 46
Asymmetrical definitions of the two ends of the link make the assignment of the role of a newly developed device problematic; the designer must decide on either a DTE-like or DCE-like interface and which connector pin assignments to use. The handshaking and control lines of the interface are intended for the setup and takedown of a dial-up communication circuit; in particular, the use of handshake lines for flow control is not reliably implemented in many devices. No method is specified for sending power to a device. While a small amount of current can be extracted from the DTR and RTS lines, this is only suitable for low power devices such as mice. While the standard recommends a 25-way connector and its pinout, the connector is large by current standards.
4.5.2 Role in modern personal computers Today, RS-232 is gradually being superseded in personal computers by USB for local communications. Compared with RS-232, USB is faster and uses lower voltages, and has connectors that are simpler to connect and use. Both standards have software support in popular operating systems. USB is designed to make it easy for device drivers to communicate with hardware. However, there is no direct analog to the terminal programs used to let users communicate directly with serial ports. USB is more complex than the RS-232 standard because it includes a protocol for transferring data to devices. This requires more software to support the protocol used. RS-232 only standardizes the voltage of signals and the functions of the physical interface pins. Serial ports of personal computers are also often used to directly control various hardware devices, such as relays or lamps, since the control lines of the interface could be easily manipulated by software. This isn't feasible with USB which requires some form of receiver to decode the serial data.
47
As an alternative, USB docking ports are available which can provide connectors for a keyboard, mouse, one or more serial ports, and one or more parallel ports. Corresponding device drivers are required for each USB-connected device to allow programs to access these USB-connected devices as if they were the original directly-connected peripherals. Devices that convert USB to RS 232 may not work with all software on all personal computers and may cause a reduction in bandwith along with higher latency. Personal computers may use the control pins of a serial port to interface to devices such as uninterruptible power supplies. In this case, serial data is not sent, but the control lines are used to signal conditions such as loss of power, or low battery alarms.
4.5.3 Standard details In RS-232, user data is sent as a time-series of bits. Both synchronous and asynchronous transmissions are supported by the standard. In addition to the data circuits, the standard defines a number of control circuits used to manage the connection between the DTE and DCE. Each data or control circuit only operates in one direction, that is, signaling from a DTE to the attached DCE or the reverse. Since transmit data and receive data are separate circuits, the interface can operate in a full duplex manner, supporting concurrent data flow in both directions. The standard does not define character framing within the data stream, or character encoding.Diagrammatic oscilloscope trace of voltage levels for an uppercase ASCII "K" character (0x4b) with 1 start bit, 8 data bits, 1 stop bit.The RS-232 standard defines the voltage levels that correspond to logical one and logical zero levels. Valid signals are plus or minus 3 to 15 volts. The range near zero volts is not a valid RS-232 level; logic one is defined as a negative voltage, the signal 48
condition is called marking, and has the functional significance of OFF. Logic zero is positive, the signal condition is spacing, and has the function ON. The standard specifies a maximum open-circuit voltage of 25 volts; signal levels of ±5 V,±10 V, ±12 V, and ±15 V are all commonly seen depending on the power supplies available within a device. RS-232 drivers and receivers must be able to withstand indefinite short circuit to ground or to any voltage level up to ±25 volts. The slew rate, or how fast the signal changes between levels, is also controlled. Because the voltage levels are higher than logic levels typically used by integrated circuits, special intervening driver circuits are required to translate logic levels. These also protect the device's internal circuitry from short circuits or transients that may appear on the RS-232 interface, and provide sufficient current to comply with the slew rate requirements for data transmission. Because both ends of the RS-232 circuit depend on the ground pin being zero volts, problems will occur when connecting machinery and computers where the voltage between the ground pin on one end, and the ground pin on the other is not zero. This may also cause a hazardous ground loop. Unused interface signals terminated to ground will have an undefined logic state. Where it is necessary to permanently set a control signal to a defined state, it must be connected to a voltage source that asserts the logic 1 or logic 0 level. Some devices provide test voltages on their interface connectors for this purpose. RS-232 devices may be classified as Data Terminal Equipment (DTE) or Data Communications Equipment (DCE); this defines at each device which wires will be sending and receiving each signal. The standard recommended but did not make mandatory the D-subminiature 25 pin connector. In general and according to the standard, terminals and computers have male connectors with DTE pin functions, 49
and modems have female connectors with DCE pin functions. Other devices may have any combination of connector gender and pin definitions. Many terminals were manufactured with female terminals but were sold with a cable with male connectors at each end; the terminal with its cable satisfied the recommendations in the standard.Presence of a 25 pin D-sub connector does not necessarily indicate an RS-232-C compliant interface. For example, on the original IBM PC, a male Dsub was an RS-232-C DTE port (with a non-standard current loop interface on reserved pins), but the female D-sub connector was used for a parallel Centronics printer port. Some personal computers put non-standard voltages or signals on some pins of their serial ports.The standard specifies 20 different signal connections. Since most devices use only a few signals, smaller connectors can often be used. For example, the 9 pin DE-9 connector was used by most IBMcompatible PCs since the IBM PC AT, and has been standardized as TIA-574. More recently, modular connectors have been used. Most common are 8P8C connectors. Standard EIA/TIA 561 specifies a pin assignment, but the "Yost Serial Device Wiring Standard" invented by Dave Yost (and popularized by the Unix System Administration Handbook) is common on Unix computers and newer devices from Cisco Systems. Many devices don't use either of these standards. 10P10C connectors can be found on some devices as well. Digital Equipment Corporation defined their own DECconnect connection system which was based on the Modified Modular Jack connector. This is a 6 pin modular jack where the key is offset from the center position. As with the Yost standard, DECconnect uses a symmetrical pin layout which enables the direct connection between two DTEs. Another common connector is the DH10 header connector common on motherboards and add-in cards which is usually converted via a cable to the more standard 9 pin DE-9 connector (and frequently mounted on a free slot plate or other part of the housing). 50
The signals are named from the standpoint of the DTE. The ground signal is a common return for the other connections; it appears on two pins in the Yost standard but is the same signal. The DB-25 connector includes a second "protective ground" on pin 1. Connecting this to pin 7 (signal reference ground) is a common practice but not recommended. Use of a common ground is one weakness of RS-232: if the two devices are far enough apart or on separate power systems, the ground will degrade between them and communications will fail, which is a difficult condition to trace.
4.5.4 Signals Commonly-used signals are: Transmitted Data (TxD) Data sent from DTE to DCE. Received Data (RxD) Data sent from DCE to DTE. Request To Send (RTS) Asserted (set to logic 0, positive voltage) by DTE to prepare DCE to receive data. This may require action on the part of the DCE, e.g. transmitting a carrier or reversing the direction of a half-duplex channel. Ready To Receive (RTR) Asserted by DTE to indicate to DCE that DTE is ready to receive data. If in use, this signal appears on the pin that would otherwise be used for Request To Send, and the DCE assumes that RTS is always asserted. 51
Clear To Send (CTS) Asserted by DCE to acknowledge RTS and allow DTE to transmit. This signaling was originally used with half-duplex modems and by slave terminals on multidrop lines: The DTE would raise RTS to indicate that it had data to send, and the modem would raise CTS to indicate that transmission was possible. Data Terminal Ready (DTR) Asserted by DTE to indicate that it is ready to be connected. If the DCE is a modem, this may "wake up" the modem, bringing it out of a power saving mode. This behaviour is seen quite often in modern PSTN and GSM modems. When this signal is de-asserted, the modem may return to its standby mode, immediately hanging up any calls in progress. Data Set Ready (DSR) Asserted by DCE to indicate the DCE is powered on and is ready to receive commands or data for transmission from the DTE. For example, if the DCE is a modem, DSR is asserted as soon as the modem is ready to receive dialing or other commands; DSR is not dependent on the connection to the remote DCE (see Data Carrier Detect for that function). If the DCE is not a modem (e.g. a null modem cable or other equipment), this signal should be permanently asserted (set to 0), possibly by a jumper to another signal. Data Carrier Detect (DCD) Asserted by DCE when a connection has been established with remote equipment. Ring Indicator (RI) Asserted by DCE when it detects a ring signal from the telephone line. 52
The standard does not define a maximum cable length but instead defines the maximum capacitance that a compliant drive circuit must tolerate. A widely-used rule-of-thumb indicates that cables more than 50 feet (15 metres) long will have too much capacitance, unless special cables are used. By using low-capacitance cables, full speed communication can be maintained over larger distances up to about 1,000 feet. For longer distances, other signal standards are better suited to maintain high speed. Since the standard definitions are not always correctly applied, it is often necessary to consult documentation, test connections with a breakout box, or use trial and error to find a cable that works when interconnecting two devices. Connecting a fully-standard-compliant DCE device and DTE device would use a cable that connects identical pin numbers in each connector (a so-called "straight cable"). "Gender changers" are available to solve gender mismatches between cables and connectors. Connecting devices with different types of connectors requires a cable that connects the corresponding pins according to the table above. Cables with 9 pins on one end and 25 on the other are common. Manufacturers of equipment with 8P8C connectors usually provide a cable with either a DB-25 or DE-9 connector (or sometimes interchangeable connectors so they can work with multiple devices). Poor-quality cables can cause false signals by crosstalk between data and control lines (such as Ring Indicator). For functional communication through a serial port interface, conventions of bit rate, character framing, communications protocol, character encoding, data compression, and error detection, not defined in RS 232, must be agreed to by both sending and receiving equipment. For example, consider the serial ports of the original IBM PC. This implementation used an 8250 UART using asynchronous start-stop character formatting with 7 or 8 data bits per frame, usually ASCII 53
character coding, and data rates programmable between 75 bits per second and 115,200 bits per second. Data rates above 20,000 bits per second are out of the scope of the standard, although higher data rates are sometimes used by commercially manufactured equipment. In the particular case of the IBM PC, baud rates were programmable with arbitrary values, so that a PC could be connected to, for example, MIDI music controllers (31,250 bits per second) or other devices not using the rates typically used with modems. Since most devices do not have automatic baud rate detection, users must manually set the baud rate (and all other parameters) at both ends of the RS-232 connection.
RTS/CTS handshaking In older versions of the specification, RS-232's use of the RTS and CTS lines is asymmetric: The DTE asserts RTS to indicate a desire to transmit to the DCE, and the DCE asserts CTS in response to grant permission. This allows for half-duplex modems that disable their transmitters when not required, and must transmit a synchronization preamble to the receiver when they are re-enabled. This scheme is also employed on present-day RS-232 to RS-485 converters, where the RS-232's RTS signal is used to ask the converter to take control of the RS-485 bus - a concept that doesn't otherwise exist in RS-232. There is no way for the DTE to indicate that it is unable to accept data from the DCE. A non-standard symmetric alternative, commonly called "RTS/CTS handshaking," was developed by various equipment manufacturers: CTS indicates permission from the DCE for the DTE to send data to the DCE (and is controlled by the DCE independent of RTS), and RTS indicates permission from the DTE for the DCE to send data to the DTE. This was eventually codified in version RS-232-E (actually TIA-232-E by that time) by defining a new signal, "RTR (Ready to Receive)," 54
which is CCITT V.24 circuit 133. TIA-232-E and the corresponding international standards were updated to show that circuit 133, when implemented, shares the same pin as RTS (Request to Send), and that when 133 is in use, RTS is assumed by the DCE to be ON at all times. Thus, with this alternative usage, one can think of RTS asserted (logic 0) meaning that the DTE is indicating it is "ready to receive" from the DCE, rather than requesting permission from the DCE to send characters to the DCE. 3-wire and 5-wire RS-232 A minimal "3-wire" RS-232 connection consisting only of transmit data, receive data, and ground, is commonly used when the full facilities of RS-232 are not required. Even a two-wire connection (data and ground) can be used if the data flow is one way (for example, a digital postal scale that periodically sends a weight reading, or a GPS receiver that periodically sends position, if no configuration via RS-232 is necessary). When only hardware flow control is required in addition to two-way data, the RTS and CTS lines are added in a 5-wire version.
Timing signals Some synchronous devices provide a clock signal to synchronize data transmission, especially at higher data rates. Two timing signals are provided by the DCE on pins 15 and 17. Pin 15 is the transmitter clock, or send timing (ST); the DTE puts the next bit on the data line (pin 2) when this clock transitions from OFF to ON (so it is stable during the ON to OFF transition when the DCE registers the bit). Pin 17 is the receiver clock, or receive timing (RT); the DTE reads the next bit from the data line (pin 3) when this clock transitions from ON to OFF.Alternatively, the DTE can provide a clock signal, called transmitter timing 55
(TT), on pin 24 for transmitted data. Again, data is changed when the clock transitions from OFF to ON and read during the ON to OFF transition. TT can be used to overcome the issue where ST must traverse a cable of unknown length and delay, clock a bit out of the DTE after another unknown delay, and return it to the DCE over the same unknown cable delay. Since the relation between the transmitted bit and TT can be fixed in the DTE design, and since both signals traverse the same cable length, using TT eliminates the issue. TT may be generated by looping ST back with an appropriate phase change to align it with the transmitted data. ST loop back to TT lets the DTE use the DCE as the frequency reference, and correct the clock to data timing.
56
FIG.6: MAX 232 MODEM INTERFACE
57
FIG 7: POWER SUPPLY LAYOUT
58
4.5.5 POWER SUPPLY DESCRIPTIONS
The present chapter introduces the operation of power supply circuits built using filters, rectifiers, and then voltage regulators. Starting with an ac voltage, a steady dc voltage is obtained by rectifying the ac voltage, then filtering to a dc level, and finally, regulating to obtain a desired fixed dc voltage. The regulation is usually obtained from an IC voltage regulator unit, which takes a dc voltage and provides a somewhat lower dc voltage, which remains the same even if the input dc voltage varies, or the output load connected to the dc voltage changes. A block diagram containing the parts of a typical power supply and the voltage at various points in the unit is shown in fig 19.1. The ac voltage, typically 120 V rms, is connected to a transformer, which steps that ac voltage down to the level for the desired dc output. A diode rectifier then provides a full-wave rectified voltage that is initially filtered by a simple capacitor filter to produce a dc voltage. This resulting dc voltage usually has some ripple or ac voltage variation. A regulator circuit can use this dc input to provide a dc voltage that not only has much less ripple voltage but also remains the same dc value even if the input dc voltage varies somewhat, or the load connected to the output dc voltage changes. This voltage regulation is usually obtained using one of a number of popular voltage regulator IC units.
59
Transformer
Rectifier
Filter
IC regulator
Load
4.5.6 IC VOLTAGE REGULATORS: Voltage regulators comprise a class of widely used ICs. Regulator IC units contain the circuitry for reference source, comparator amplifier, control device, and overload protection all in a single IC. Although the internal construction of the IC is somewhat different from that described for discrete voltage regulator circuits, the external operation is much the same. IC units provide regulation of either a fixed positive voltage, a fixed negative voltage, or an adjustably set voltage.A power supply can be built using a transformer connected to the ac supply line
to step the ac voltage to a desired amplitude, then rectifying that
ac voltage, filtering with a capacitor and RC filter, if desired, and finally regulating the dc voltage using an IC regulator. The regulators can be selected
60
for operation with load currents from hundreds of milli amperes to tens of amperes, corresponding to power ratings from milliwatts to tens of watts.
THREE-TERMINAL VOLTAGE REGULATORS: Fig shows the basic connection of a three-terminal voltage regulator IC to a load. The fixed voltage regulator has an unregulated dc input voltage, Vi, applied to one input terminal, a regulated output dc voltage, Vo, from a second terminal, with the third terminal connected to ground. For a selected regulator, IC device specifications list a voltage range over which the input voltage can vary to maintain a regulated output voltage over a range of load current. The specifications also list the amount of output voltage change resulting from a change in load current (load regulation) or in input voltage (line regulation).
FIG 8:Fixed Positive Voltage Regulators: IN OUT UNREGULA TED DC VOLTAGE
7805
GND
The series 78 regulators provide fixed regulated voltages from 5 to 24 V. Figure 19.26 shows how one such IC, a 7812, is connected to provide voltage regulation with output from this unit of +12V dc. An unregulated input voltage Vi 61
is filtered by capacitor C1 and connected to the IC’s IN terminal. The IC’s OUT terminal provides a regulated + 12V which is filtered by capacitor C2 (mostly for any high-frequency noise). The third IC terminal is connected to ground (GND). While the input voltage may vary over some permissible voltage range, and the output load may vary over some acceptable range, the output voltage remains constant within specified voltage variation limits. These limitations are spelled out in the manufacturer’s specification sheets. A table of positive voltage regulated ICs is provided in table
62
TABLE 2 Positive Voltage Regulators in 7800 series IC
Output Voltage (V)
Minimum Vi (V)
Part 7805
+5
7.3
7806
+6
8.3
+8
10.5
+10
12.5
+12
14.6
+15
17.7
+18
21.0
7808
7810
7812
7815
7818
4.5.7GUI MODULES
63
Introduction The most commonly used Character based LCDs are based on Hitachi's HD44780 controller or other which are compatible with HD44580. In this project document, we will discuss about character based LCDs, their interfacing with various microcontrollers, various interfaces (8-bit/4-bit), programming, special stuff and tricks you can do with these simple looking LCDs which can give a new look to your application.
TABLE 3 64
65
TABLE 4:CHARACTER LCD PINS WITH 2 CONTROLLER
Usually these days single controller LCD modules are used more in the market. So in the project document we will discuss more about the single controller LCD, the operation and everything else is same for the double controller too.
66
DDRAM
-
Display
Data
RAM
Display data RAM (DDRAM) stores display data represented in 8-bit character codes. Its extended capacity is 80 X 8 bits, or 80 characters. The area in display data RAM (DDRAM) that is not used for display can be used as general data RAM. So whatever you send on the DDRAM is actually displayed on the LCD. For LCDs like 1x16, only 16 characters are visible, so whatever you write after 16 chars
is
written
in
DDRAM
but
is
not
visible
to
the
user.
Figures below will show the DDRAM addresses of 1 Line, 2 Line and 4 Line LCDs.
CGROM
-
Character
Generator
ROM
Now you might be thinking that when you send an ascii value to DDRAM, how the character is displayed on LCD? so the answer is CGROM. The character 67
generator ROM generates 5 x 8 dot or 5 x 10 dot character patterns from 8-bit character codes (see Figure 5 and Figure 6 for more details). It can generate 208 5 x 8 dot character patterns and 32 5 x 10 dot character patterns. User defined character patterns are also available by mask-programmed ROM.
Figure 9: LCD characters code map for 5x8 dots
68
As can be seen in both the code maps, the character code from 0x00 to 0x07 is occupied by the CGRAM characters or the user defined characters. If user want to display the fourth custom character then the code to display it is 0x03 i.e. when user send 0x03 code to the LCD DDRAM then the fourth user created charater or patteren will be displayed on the LCD. CGRAM
Character
Generator
RAM
As clear from the name, CGRAM area is used to create custom characters in LCD. 69
In the character generator RAM, the user can rewrite character patterns by program. For 5 x 8 dots, eight character patterns can be written, and for 5 x 10 dots, four character patterns can be written. Later in this project document i will explain how to use CGRAM area to make custom character and also making animations to give nice effects to your application. BF
-
Busy
Flag
Busy Flag is an status indicator flag for LCD. When we send a command or data to the LCD for processing, this flag is set (i.e BF =1) and as soon as the instruction is executed successfully this flag is cleared (BF = 0). This is helpful in producing and exact
ammount
of
delay.
for
the
LCD
processing.
To read Busy Flag, the condition RS = 0 and R/W = 1 must be met and The MSB of the LCD data bus (D7) act as busy flag. When BF = 1 means LCD is busy and will not accept next command or data and BF = 0 means LCD is ready for the next command or data to process. Instruction
Register
(IR)
and
Data
Register
(DR)
There are two 8-bit registers in HD44780 controller Instruction and Data register. Instruction register corresponds to the register where you send commands to LCD e.g LCD shift command, LCD clear, LCD address etc. and Data register is used for storing data which is to be displayed on LCD. when send the enable signal of the LCD is asserted, the data on the pins is latched in to the data register and data is then moved automatically to the DDRAM and hence is displayed on the LCD. Data Register is not only used for sending data to DDRAM but also for CGRAM, the address where you want to send the data, is decided by the instruction you send
70
to LCD. We will discuss more on LCD instuction set further in this project document. Commands
and
Instruction
set
Only the instruction register (IR) and the data register (DR) of the LCD can be controlled by the MCU. Before starting the internal operation of the LCD, control information is temporarily stored into these registers to allow interfacing with various MCUs, which operate at different speeds, or various peripheral control devices. The internal operation of the LCD is determined by signals sent from the MCU. These signals, which include register selection signal (RS), read/write signal (R/W), and the data bus (DB0 to DB7), make up the LCD instructions (Table 3). There are four categories of instructions that: Designate LCD functions, such as display format, data length, etc. Set internal RAM addresses Perform data transfer with internal RAM Perform miscellaneous functions
71
TABLE 5: Command and Instruction set for LCD type HD44780
72
4.5.8SOFTWARE PLATFORM AND PROGRAM 73
The programming platform used for the project design specific functions are MPLAB and ICPROG. For the purpose of system based interfacing hyperterminal or telnet may be used. #include
#include void mcu_init(); void lcd_init(); void command(char); void write(char); void lcd_dis(const unsigned char *word,unsigned int n); void del(); void delay(unsigned int del); void forward(); //void reverse(); //void right(); //void left(); //void stop(); void mob_init();
74
void ser_init(); void ser_out(unsigned char); void ser_dis(const unsigned char*da,unsigned char no); unsigned char v[25],b; unsigned int s1; unsigned char dac,time,i,j,x,k; bit a; adc(char dat); unsigned char mv,adc_s,adc_t,ch; unsigned int temp; unsigned char aa; void msg_rx(); void msg_send(); void forward(); //void reverse(); //void right(); //void left(); //void stop(); static bit rig_rev @((unsigned) &PORTD*8+0); 75
static bit rig_for @((unsigned) &PORTD*8+1); static bit lef_for @((unsigned) &PORTD*8+2); static bit lef_rev @((unsigned) &PORTD*8+3);
void main() {
TRISC=0xC1;
// 1100 0001
lcd_init();
//
lef_for=0;
//
lef_rev=0;
//
rig_for=0;
//
rig_rev=0;
// STOP
command(0x01);//clear display command(0x80); lcd_dis("GSM BASED T/F
",16);
command(0xC0); lcd_dis("MONITOR&CONTROL
",16); 76
del();del();del(); mcu_init(); ser_init(); mob_init(); del(); command(0x01);//clear display //
command(0x80);
//
lcd_dis("Temp:000
",16);
// // stop(); /* stop(); del();del();del();
forward(); del();del();del(); reverse(); del();del();del(); right(); del();del();del(); 77
left(); del();del();del(); stop(); */ while(1) { s1++; adc_s=adc(0x81); adc_t=adc(0x89); //adc_t=adc(0x89); command(0x85); write(adc_s/100+0x30); write(adc_s%100/10+0x30); write(adc_s%10+0x30); command(0xc5); write(adc_t/100+0x30); write(adc_t%100/10+0x30); write(adc_t%10+0x30); //
if(s1==1000) 78
//{ //command(0x80); //
lcd_dis("SMS RECEIVING...
",16);
//del();del();del(); //s1=0; //
msg_rx();
//} if(s1==500) { command(0x80); lcd_dis("SMS SENDING...
",16);
del();del();del(); //s1=0; msg_send();}
} }
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adc(char dat) { temp=0; for(aa=0;aa<6;aa++) { ADCON0=dat; for(j=0;j<200;j++); ADGO=1; while(ADGO); ADIF=0; mv=((ADRESH*255)+ADRESL)/4; temp=temp+mv; } //
mv=temp/6; return(mv); 80
}
void mcu_init() { TRISA=0XFF; TRISB=0X00; TRISD=0X00; TRISE=0X00; ADCON1=0X82; }
void mob_init() { ser_out('A');ser_out('T');ser_out(0x0d); del(); //
ser_out('A');ser_out('T');ser_out(0x0d);
//
del(); 81
//
ser_out('A');ser_out('T');ser_out(0x0d);
//
del();
//
ser_out('A');ser_out('T');ser_out(0x0d);
//
del();
//
ser_out('A');ser_out('T');ser_out(0x0d);
//
del();
//
ser_dis("AT+CPMS=",8);
//
ser_out('"'); //
ser_out('S');
//
ser_out('M');
//
ser_out('"'); //
//
ser_out(0x0d); del(); ser_dis("AT+CMGF=1",9); ser_out(0x0d); del(); del();
}
82
/*void msg_rx() { i=j=1;CREN = 1; ser_dis("AT+CMGR=1",9); ser_out(0x0d); del();del(); CREN = 0; if(i>25) { if(v[4]=='F')
forward();
//
else if(v[4]=='B') reverse();
//
else if(v[4]=='L') left();
//
else if(v[4]=='R') right();
//
else if(v[4]=='S') stop();
//
else ; ser_dis("AT+CMGD=1",9); ser_out(0x0d); del();
} 83
} */
void msg_send() { ser_dis("AT+CMGS=",8); ser_out('"'); ser_dis("9677740412",10); ser_out('"'); ser_out(0x0d); del();del(); ser_dis("VOLT:",5); ser_out(adc_s/100+0x30); ser_out(adc_s%100/10+0x30); ser_out(adc_s%10+0x30); ser_dis("CURRENT:",8); ser_out(adc_t/100+0x30); ser_out(adc_t%100/10+0x30); 84
ser_out(adc_t%10+0x30); ser_out(0x1a); del(); del(); del(); }
/*void interrupt funct(void) { if(RCIF==1)
// chk the rx flag
{ RCIF=0; x=RCREG; if(i>25) { v[j]=RCREG; j++; } else i++; 85
} }*/
86
void ser_init() { SPBRG= 129;
// for 9600 baud rate 4MHz crystal
BRGH = 1;
// baud rate high
SYNC = 0;
// asynchronous mode
SPEN = 1;
// serial port enable
RCIE = 1; CREN = 0;
// interrupt set // Rx enable
TXEN = 1;
// Tx enable
GIE=1;PEIE=1; }
void ser_out(unsigned char ss) { 87
TXREG = ss; while(!TXIF); TXIF = 0; delay(1000); }
void ser_dis(const unsigned char*da,unsigned char no) { unsigned char ss; for(ss=0;ss
void forward() { command(0xc0); lcd_dis(" lef_for=1;
FORWARD
",16);
//on
lef_rev=0; delay(20); 88
rig_for=1; rig_rev=0; }
/*void reverse() { command(0xc0); lcd_dis("
REVERSE
",16);
lef_for=0; lef_rev=1; rig_for=0; delay(20); rig_rev=1; }*/
/*void right() { 89
command(0xc0); lcd_dis("
RIGHT
",16);
lef_for=1; lef_rev=0; rig_for=0;
//right
delay(20); rig_rev=1; delay(55000); stop(); }
void left() { command(0xc0); lcd_dis("
LEFT
",16);
lef_rev=1; lef_for=0; delay(20); 90
rig_for=1;
//left
rig_rev=0; delay(55000); stop(); }
void stop() { command(0xc0); lcd_dis("
STOP
",16);
lef_for=0; lef_rev=0;
// STOP
rig_for=0; rig_rev=0; }*/
void delay(unsigned int del) 91
{ while(del--); }
void lcd_init() { TRISB=0X00; TRISE=0X00; command(0x38); command(0x06); command(0x0C); command(0x01); // lcd clr }
void command(char s) { PORTB=s; PORTE=0x04;
// 0000 0100 92
for(k=0;k<125;k++); PORTE=0x00;
// 0000 0000
for(k=0;k<200;k++); }
void write(char s) { PORTB=s; PORTE=0x05; for(k=0;k<125;k++); PORTE=0x01;
// 0000 0001
for(k=0;k<200;k++); }
void lcd_dis(const unsigned char *word,unsigned int n) { unsigned char i; 93
for(i=0;i
void del() { delay(65000); delay(15000); }
94
5 . ADVANTAGES AND DISADVANTAGES
5.1 ADVANTAGES
PROVIDES INDEPENDENCE FROM ENERGY CRISIS EFFICIENCY BASED ON THE GENERATING SOURCE HIGHER CONTROL CENTRE DESIGN COMPARATIVELY MORE INTEGRATED THAN EXISTING SYSTEMS
95
5.2 DISADVANTAGES LAPTOP/SYSTEMS CANNOT BE USED CONTINUOUSLY LAPTOP
BASED
NETWORK
COULD
INVOLVE
GREATER
APPARATUS USAGE APPLICATION ON LARGE SCALE CANNOT BE PREDICTED
6. CONCLUSION
The design of the project envisages a household power system which could have its own generation and replication of all functions performed by the electricity board towards energy control within the household itself including load shedding, per room power switching control etc. However on analyzing the completed project based on current status only some main functions of a control centre were possible to replicate in the working system. The following controls have been successfully implemented: Power on/off control 96
Monitoring control
However control functions like load shedding and each room switching control couldnot be actuated because of the programming conditional complexity involved. The actuation of these controls require an actual household as only then the conditional instances can be encapsulated in program modules. Since for principle display such an arrangement is not possible, hence under current implementation the controls have been limited. The actuation of the system in future on actual households would allow for greater programming flexibility and as such all designed controls could be conceptualized and tested to display a completely independent household power system with integrated generation, transmission, distribution and control. 7.0 BIBLIOGRAPHY 1. Xiaofan Jiang, Computer Science Department, University Of Berkeley, Wireless Building Energy Monitoring And Local : An Intelligent Power Network 2. ZW Windmill Series :Operations Manual 3. J.R Bumby, N.Stannard and R.Martin ,A Permanent Magnet Generator For Small Scale Wimdmills, 4. M. Muthukumar,N. Sureshkumar,MA. Bhadri Narayan, A Wireless Sensor Network Communication Model for Automation of Electric PowerDistribution 5. Reza Ehsani ,Introduction to GPS Guidance Systems 97
6. Geoffrey Blewitt, Department of Geomatics, University of Newcastle ,Basics of the GPS Technique: Observation Equations 7. Altera,Altia and Echelon Whitepaper,The "Energy Aware" Appliance Platform: A New Approach to Energy Control
98
99
APPENDIX-1 COST ANALYSIS
COST ANALYSIS
Overall Project Cost: Rs.60000/-
Software Cost: 1.MPLAB : Rs.10000 2.ICPROG: Rs.8000 Hardware Requirements Cost: 100
S.NO. NAME
QUANTITY
1.
BLADES
3
2.
SOLAR PANELS
2
3.
STAND
4.
PANEL HOLDER
5.
BATTERY
1
6.
INVERTER
1
7.
GSM MODEM
2
8.
PCB DESIGN
2
9.
CONNECTING WIRE
2 COILSPANS
10.
LAMP
PRICE
101
APPENDIX-2
102
PHOTOS
103
104
105
106
