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Aerostats, Helikites, and Balloons in Agriculture
Published in K. R. Krishna, Aerial Robotics in Agriculture, 2021
The ‘high altitude wind power’ is defined as harnessing power from wind that blows at higher altitudes in the sky. The power generated is relayed using tethers or cable, to ground stations. We may note that wind velocity recorded at higher altitudes is usually much higher than at altitudes close to ground. The wind velocity is a crucial aspect of aerostat-mediated high-altitude wind power generation. A doubling of wind velocity increases the power generation potential by 8 times the original. Tripling of wind velocity means 27 times more power could be generated. There are several methods through which we can harness wind’s kinetic energy and convert it to electrical energy and transmit (Wikipedia, 2019). Here, we are concerned more with aerostats with lighter-than-air system. It adopts a tethered aerostat to act as a platform for a turbine that harnesses wind’s kinetic energy and produces electrical energy. Incidentally, heavier-than-air methods that involve tethered parafoils have also been utilized to harbor a wind turbine.
Modular Wind Energy Systems
Published in Yatish T. Shah, Modular Systems for Energy and Fuel Recovery and Conversion, 2019
Airborne wind turbines may operate in low or high altitudes; they are part of a wider class of Airborne Wind Energy Systems (AWES) addressed by high-altitude wind power and crosswind kite power. When the generator is on the ground [93,95–99], the tethered aircraft need not carry the generator mass or have a conductive tether. When the generator is aloft, a conductive tether would be used to transmit energy to the ground or used aloft or beamed to receivers using microwave or laser. Kites and helicopters come down when there is insufficient wind; kytoons and blimps may resolve the matter with other disadvantages. Also, bad weather, such as lightning or thunderstorms, could temporarily suspend use of the machines, probably requiring them to be brought back down to the ground and covered. Some schemes require a long power cable and, if the turbine is high enough, a prohibited airspace zone [93,95–99].
Coupled trajectory optimization and tuning of tracking controllers for parafoil generator
Published in International Journal of Green Energy, 2023
Xinyu Long, Mingwei Sun, Zengqiang Chen, Yongshuai Wang
In order to protect global environment and reduce carbon emission, it is imperative to develop green energy (Zia et al. 2021). Wind energy is sustainable and available almost everywhere, which strongly boosts the progress of wind power generation technology (Lehna, Hoppmann, and Heinrich et al. 2021; Mahdi et al. 2020; Miele, Bonacina, and Corsini 2022; Mitchell, Blanche, and Harper et al. 2021; Neeraj and Beena 2022; Thresher, Robinson, and Veers 2007). Traditional ground wind power generation is mainly using the wind below 200 m with low and turbulent wind speed. Furthermore, the wind power site construction requires excessive land and the installation is complex and expensive. In fact, the construction cost is almost proportional to the quintic power of the blade altitude (Kim and Park 2009). Compared with the ground wind, wind at high altitudes has high speed and steady direction, which implies high-quality wind energy. High altitude wind power generation (HAWPG), as a new concept, is proposed to capture the wind energy using the parafoil at high altitudes more than 200 meters (Canale, Fagiano, and Milanese 2007, 2008; Loyd 1980; Udo and Philip 2013). However, the research of the HAWPG is still at an early stage with many open problems. Specifically, how to maximize the power generation while ensuring stable motion of the parafoil remains open. In (Canale, Fagiano, and Milanese 2009) and (Sean, Gregory, and Dominique 2018), it was confirmed that the inclined lying figure eight trajectory can obtain the maximum power generation, and can also prevent the cables from wrapping. However, this category of trajectories is just a general concept. For the HAWPG parafoil models with varying configurations (such as the cable length, parafoil area, cable and parafoil weight, etc.), the appropriate forms of the trajectory should be carefully sought. In fact, the parameterization of parafoil trajectory optimization is necessary for the following implementation. After obtaining the trajectory with maximum power generation, it is crucial to control the parafoil to track this trajectory accurately. The required inclined lying figure eight trajectory makes the pitch and yaw dynamics highly coupled, which leads to significant difficulties in independent control loop tuning. In addition, the remarkably nonlinearly aerodynamic uncertainties and the wind perturbation should also be considered because of the quite relative low-speed of the airfoil comparing with that of the wind. This is different from the traditional control of high-speed aircraft (Omab, Smb, and Cz et al. 2021). Therefore, a comprehensive trajectory optimization and an efficient tracking controller should be sought to guarantee the sufficient benefits of the HAWPG.