A Novel Airborn Multi-Turbin Floating Wind Energy Generator - May 3, 2023


Saeed Rahmani, Ali Ghambari

The ground mounted wind turbines extract low wind energy. The increasing trend of energy consumption causes the wind energy become important but it energy extraction still is in amount and wind energy plans may not satisfy the future energy need. The contra rotor wind energy generators the benefits two wind turbines and has higher wind energy extraction ratio. but these wind turbines are complicate to manufacture and still work at low altitude or monuted on the ground which extract low wind energy. The flying kite energy which uses kites pushed by wind flow and it pulls a string and the string turns shaft of an electrical generator but the flying kit are hard to control as they become untasable in high wind speeds. the floating savious style wind turbines that floating at high altitude and generate electricity send to ground via a conductive tether but the consruction of damm are costly and not possible everywhere. In this paper, to increase the wind energy extraction efficiency a new airborn multi wind turbin generator is proposed. The new wind turbine extract more wind energy as it will be at high altitude. The wind turbin is low cost and also need minimum structural materials and small ground..

KEYWORDS: Global warming, wind energy, wind turbin, electrical generator, efficiency, electrical generator, airborne energy

The air friction with the earth surface is high because of mountains, buildings, trees which reduces the wind speed, and wind turbines extract a low energy. The low altitude winds are low speed because of air friction with earth surface. They have a low wind energy.. Every year countires parliment legislate wind energy plans but because almost all these plans are ground mounted wind turines they extract not enough energy and hardly satisfy the plan pupose. The human civilication energy need is increasing and the movement to the wind power extraction started but still this technology is not matured enoug and it cannot extract the needed energy from the wind. To solve this problem several solutions proposed so far. Convetional wind turbines has a single turbine but contra-rotor wind turbines has two turbine which are connected as both sides of an type of eletrical generator that has two shafts but although this contra rotor wind turbines extract more energy but the wind speed near ground surface is weak that is generate still not satifying wind energy. Also, the contra roto wind tubines has uses a generator that has two rotors inside and so this generator has two shaft and one wind turbine is connected to each shaft. It will have totally two wind turbines and they rotate when wind blow but in opposite directions because the blade angle of the two turbines designed to be in opposit.. Flying kite have a wind area that can collect more wind energy. The flying kite can extract 40 times more energy than a similar wind turbin with the same cost. Flying kite will be flying at sky and it pulles a string that turns an electrical generator but these flying kite at sky need to be controlled and their pitch angle is controlled. Because when they ascend their pitch angle is andjusted so it collected wind energy, and it descend its pitch angle is controlled so it does not collect wind energy and it easily come to back to ground station. In fact, the flying kite should be controlled so that it perodically ascend and descend from the ground. Futhermore, the flying kite although has a high energy extraction ratio but they need a complicated control strategy to control their pitch angle during operation. inflatable cyrlandircal shabed wind turbines rotate around their horizontal axis and rotate a generate connected to it. This wind turbine are savrnois style wind tubine but are filled with helium gas and float at a high altitude and tranmit generated elecgtrcity to the ground via a enforced cable but damms are costy, because damms need a huge amount of construction materials and takes a long time to construct. It also need tranmission line to deliver electrixal energy to the national grid.. Moreover, the floating savonus wind turbine are cyladrical shap wind turbines that filled with lighter than air gas and they are floating at high altitude . To solve these problems in past solutions, in this paper, . the high altitude winds are persistent and stronger than low altitude winds and the proposed wind turbin in this paper will operate at high altitudes extracts higher wind energy compared to ground mounted wind turbines. . When at ground there wind are weak or not persistent, this propsoed wind turbine in in exposure of high altitude high speed wind and generates electrical energy tranmit to earth. . When at ground there wind are weak or not persistent, this propsoed wind turbine in in exposure of high altitude high speed wind and generates electrical energy tranmit to earth.

The proposed wind turbine consisted of an array of floating wind turbine. Each of the wind turbines is a light weight wind turbine with a light weight permanent magnet electrical generator. This wind turbine is framed with an inflatable round structure filled with a lighter than air gas allow it be aloft as shown in Fig.1.
Fig. 1. The floating ligh weight wind turbine generator framed with a inflatable circular ballon filled with lighter than air gas.
The used electrical generator is a DC permanent magnet generator which an aluminum envelop and aluminum shaft. The generator is designed to be light weight. The generator has two series axial flux generators inside with co-axis shaft connected to the main shaft.
Fig. 2. Light weight electrical generator with aluminum made shaft and envelop.
Multiple number of the described floating turbines are connected together and framed in an rectangular aluminum frame. The whole structure will be floating at high altitude. The electrical generators terminals are connected together in parallel connected and whole multiple wind turbine will have two output terminals which is a single phase DC current.
Fig. 2. Multiple floating wind turbines framed in an rectangular aluminum frame floating at high altitude.
The tether connect the multi-wind turbine system to the ground is a conductive wire coated with cotton. Three strong fibers also are inside of the cotton. Also, a data cable included inside the cotton as all shown in Fig.4. The data cable is for sensing the condition of the electrical generators and monitoring them for possible incident fault detection.
Fig. 3. The tether has an condutive wire and three strong ligh weigh carbon fibers and data cabel coated with cotton.
The generated electrical energy by the wind turbines is transferred via a conductive tether to the ground as shown in Fig. 3. The whole structure will be floating at high altitude and it will benefit from high altitude winds with high speed, persistence speed in other words high wind energy density.
Fig. 4. The generated wind energy is transfered to ther ground via the conductive tethers.
The tether connect the floating muti-wind turbine system to the ground station. This ground station has foundation and on this foundation a drum control the tether length. For reducing the tether length the drum turns and tether is turned around the drum. For increasing the tether length to increase the floating multi-wind turbine system the drum turns in opposite direction and released the tether. The generated electricity then is transferred to a power transformer as shown in Fig.6. This is a step up power transformer increase the the voltage. The voltage increase because it should be compatible with grid voltage. The other reason for increasing the volatile is that because the electrical energy should be transferred the high voltage will have lower electrical loss at transmission line. At the consumption point, the electrical voltage again will be reduced to be compatible with consumer electrical or electronic devices.
Fig. 5. The ground station receives the electrical energy via the tether and also control the tether length The electrical voltage is increased by step up power transformer to be fed into grid.
A floating wind farm will be at high altitude by using several number of such floating multi-wind turbine systems. The generated electricity by such wind turbines is transferred to their corresponding ground stations and collected together to be fed into electrical grid.
Fig. 6. A high altitude floating wind farm consisted of several floating multi wind turbine generator.
The proposed wind turbine has a lower cost as it does not need foundation, tower, gearbox and large ground area compared to ground mounted wind turbine. It also generate more electrical energy as it benefit from high altitude winds with high wind speed. Also, in contrast to the ground mounted wind turbines and wind farms that has beauty issues for the nature this wind turbine will be at high attitude not visible by naked eyes. There are many companies worldwide that deploy similar wind farms as it generated high energy per occupied space area..

The current wind energy technology is not cable of extract considerable wind energy although the human energy consumption increases. In this paper a new floating multi-wind turbine system proposed. The proposed wind turbine consisted an array of floating wind turbines that framed with an circular lighter than air structure. The electrical energy is generated by the wind turbine and are transmitted to a ground station via a conductive enforced tether, where the electrical voltage is increases by power transformer to be fed to national grid.

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