wireless power transmission through sps

WIRELESS POWER TRANSMISSION THROUGH SPS (SOLAR POWER

SATELLITE)

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CONTENTS....WPT basics.Types of WPT.Difference b/w microwave and laser

transmission.Block diagram of WPT using microwave

beam.SPS - working, flow chart.Overview of system design.Pros and Cons.Conclusion.

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WIRELESS POWER TRANSMISSION (WPT)

Nicola Tesla proposed the theory of wireless power

transmission. Transmission of energy from one place to

another place without using wires. Three main systems used for WPT :• Microwaves• Resonance• Solar cells

Nicola Tesla proposed the theory of wireless power

transmission. Transmission of energy from one place to

another place without using wires. Three main systems used for WPT :• Microwaves• Resonance• Solar cells

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WHY WPT ???ReliableEfficientFastLow maintenance costCan be used for short range or long rangeReduction of losses during transmission and

distribution of electrical energy.Need for grids, substations etc are eliminated.Noble alternative for electrical transmission.

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TYPES OF WPT .... There are mainly three major types of wireless energy transfer

Short range – INDUCTIVE COUPLING

Medium range – RESONANT COUPLING

Long range power transfer – ELECTROMAGNETIC RADIATION

Microwave methodLaser method

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Microwave vs. Laser Transmission MICROWAVE

LASERTransmission via radio

waves.More developed.High efficiency upto 85%.

Cause interference with satellite communication industry.

Losses occur due to Atmospheric absorption and scattering by clouds, fog, rain etc is less.

transmission via laser beam.Recently developed.Allows the efficient

transmission of power (40-50%).

Confirms to limit an eye and skin damage.

Atmospheric absorption and scattering by clouds, fog, rain etc causes up to 100 % losses.

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Block Diagram of Microwave Method of Long Range Power Transfer

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... SPS ... ... SOLAR POWER SATELLITE ...

Solar Power Satellites (SPS) have proposed to collect solar energy in space and then beam it down to earth.

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HOW SPS WORKS ???

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FLOW CHART OF SOLAR POWER TRANSMISSION

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OVERVIEW OF SYSTEM DESIGN.....It consists of :I. Solar Panel.

II. Spacetenna ( antenna on satellite ).

III.Rectenna ( RECTifyin g anTENNA).

IV. Orbit selection Systematic view.

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SOLAR PANELSet of solar photovoltaic modules electrically

connected and mounted on a supporting structure.

Photovoltaic module is a packaged , connected assembly of solar cells.

Solar panels use photons(light energy) from sun to generate electricity through photovoltaic effect.

Solar panels were first used in space in 1958.

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(ii) - SPACETENNA: (Antenna on Satellite) Spacetenna is a triangular prism with a length of

800 m and sides of 100 m.The transmitting antenna on the horizontal under

surface faces the earth, and the other two sides of the prism carry solar arrays.

The faces of prism are embedded with photovoltaic cells .These cells would convert solar energy into electricity, which in turn power onboard , Microwave Generator.

The microwave thus produced travels through atmosphere & collected by RECTENNAS on earth.

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....The Spacetenna has a square shape with dimensions

132 m by 132 m which is regularly filled with 1936 segments of sub array.

The sub array is also a square shape whose edges are 3 m .There will be about 2.6 million antenna elements in Spacetenna.

Spacetenna is composed of pilot signal receiving antennas followed by detectors finding out the location of rectenna on earth.

Moreover, the pilot signal frequency & the frequency for the energy transmission are different from each other.

It will prevent each other from interfering & makes it possible to find the accurate direction of specified rectenna.

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CONFIUGRATION OF SPACETENNA..

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(iii) - RECTENNA: (RECTIfying anTENNA) mesh of an array of dipole antennas connected to diodes converting the radio frequency signal into DC voltage, which is then converted into regular AC electricity which is wired to homes, factories etc.

It can be considered as a base station of Geosynchronous satellite. Microwaves of 2.45 GHz frequency is used to transmit power from satellite to rectenna.

. A simple rectenna can be constructed from a Schottky diode placed between antenna dipoles as shown in Fig.

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POWER CAPTURED BY RECTENNA...Half of the power captured is scattered back and half is delivered to the load.The conversion from AC power to the DC power by means of rectifying device.Types of Rectification schemes : Half wave. Full wave. Why full wave rectification ? Large Vmin

Smaller ripple factor .Full wave rectification by two diodes.Diode’s inputs are 180 degree out of phase.

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5,000 MW Receiving Station (Rectenna).This Station is about a mile & a half long in US.

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(iv)-ORBIT SELECTION SCHEMATIC VIEWIn LEO, a 11,00 Km altitude equatorial orbit will be used. This choice minimizes the transmission cost and the distance of power transmission from space.

If it was in GEO ( that is 35,800 Km from the earth ) then the transmitting antenna would have to be 40 times larger than LEO one- or else the receiving station would have to be 40 times larger.

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WHY TO USE SPS ????More intense sunlight.Unlimited energy resource.Energy delivered anywhere in the world.Zero fuel cost.Zero co2 emission – environment safe.Waste heat is radiated back into space.No air or water pollution is created during the

generation.Concept is simpler than the other most power

systems here on the earth.

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......SPS doesn’t use up the valuable surface area

on the earth.Solar radiation can be more efficiently

collected.Space gets full power 24 hours a day.No effect of storms.Eco- friendly and maintenance free energy

resource.

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DISADVANTAGES...Issues identified during DOE study :Complexity – long years to complete.

Size- 6.5 miles long by 3.3 miles wide. transmitting antenna about 1.5 mile in diameter (1

km)Cost – prototype would have cost $74 billion.Interference with communication satellitesWould require a network of 100’s of satellite.Heavy Launch costThe large scale of space solar power require

international financing.

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CONCLUSION...SPS is still more expensive than ground

based solar power & other energy sources. Yet even now, a small SPS system could be economically justified to provide unavailable emergency power for natural disaster situations, urban blackouts & satellite power failures.

For WPT via SPS to become reality, we require:

Government support.Cheaper launch prices.Involvement of private sector.

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REFERENCES...W.C. Brown, “Experiments Involving a Microwave

Beam to Power and Position a Helicopter”, IEEE Transactions on Aerospace Electronic Systems. Vol. AES-5, no. 5, pp 692-702

"http://en.wikipedia.org/wiki/Rectennas"Satellite Power System Concept Development and

Evaluation Program July 1977 - August 1980. DOE/ET-0034, February 1978.

Tesla, N., “The transmission of electric energy without wires”, The thirteenth Anniversary

Number of the Electrical World and Engineer, March 5, 1904

- http://friendsofcrc.ca/SHARP/sharp.html

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