Airborne Wind Turbine Research Articles

Power conversion system for high altitude wind power generation with medium voltage AC transmission

High Altitude Wind Power (HAWP) generating system provides clean energy at low cost and high capacity factor due to reduced size of the turbine and high speed streamlined wind at high altitude. An air-borne wind turbine (AWT) at high altitude extracts kinetic energy from wind using buoyancy provided by the blimp/aerostat. The generated electrical power is then transmitted to the ground based station (without any power conditioning) using the transmission lines (tether). The power conversion system (PCS) for harnessing HAWP is proposed in this paper. The proposed PCS consists of a three-level neutral point clamped (NPC) rectifier, a three-level NPC DC–DC converter followed by a two-level inverter. Modelling, design and control of the PCS are presented and discussed. The PCS provides generation side maximum power-point tracking (MPPT) using sensorless optimal torque control technique. The DC–DC converter provides electrical isolation as well as voltage step-down functions. A modified proportional resonant (PR) control which can selectively eliminate lower order current harmonics of the grid-connected inverter is also presented. The proposed control scheme of the PCS is evaluated through simulation studies using software programs like PSIM and MATLAB. A scaled-down 1 kW laboratory prototype of the complete PCS is designed, built and tested. The experimental test results obtained validate the proposed control scheme for efficient power generation from high altitude wind and interface to the grid/load.

複合高空発電プラットフォームの基礎研究

This is studying platform to use hybrid of solar photovoltaics and wind power generation in high altitude. Harvesting wind energy at high altitudes requires a different approach involving various electro-mechanical mechanisms and tethering transfer between an airborne wind turbine and a ground system. Furthermore, kite material wants to use lightweight solar photovoltaics device in this plan. So, we were stacking kite attention in this time. Sled kite can carry small capacity. However stacking kite research report is nothing in the world. This paper is a comparison with dynamic characteristic and management characteristic 2 kinds of connect type

Lightning field behavior around grounded airborne systems

A variety of innovative airborne concepts are being developed to capture the wind energy available at higher altitudes, facilitate wireless communication and provide heavy lift capability. These airborne systems will be in close proximity to cloud cover and exposed to increased risk of lightning strikes. A two-dimensional physics based formulation that was recently developed to investigate the potential field behavior about circular sections was used to develop uniform and tapered cylindrical elements. These elements were then combined to approximate the total charge and lightning behavior about an airborne wind turbine and a heavy lift airship. Surface electrical charge and lightning collection area are developed as a function of elevation, body shape, cloud cover and leader properties. The surface charge density is utilized to compute the degree of field intensification on the body periphery in order to determine the level of susceptibility of the airborne system to lightning strikes. It was observed that as airborne bodies move closer to the thundercloud the ambient potential field becomes more highly perturbed and leads to greater risk of lightning strikes. The lightning collection area was shown to increase with elevation of the airborne body and decrease with increase in the leader propagation angle.

Weight Optimization of a Cooling System Composed of Fan and Extruded-Fin Heat Sink

This paper details the weight optimization of forced convection cooling systems, composed of a fan and an extruded-fin heat sink, required for a dc-dc converter of an airborne wind turbine system. The presented investigations detail the optimization of the heat sink's fins with respect to minimum weight and the selection of a suitable fan for minimum overall system weight. A new analytical cooling system model is introduced, and the calculated results are compared to the results determined with a preexisting analytical model and finite-element model simulations. The comparison to experimental results demonstrates the accuracy improvements achieved with the proposed methods. Compared to commercially available products, a weight reduction of 52% is achieved with the proposed optimization procedure for the required heat sink system with R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th,S-a</sub> =1 K/W.

Conceptualization and Multiobjective Optimization of the Electric System of an Airborne Wind Turbine

Airborne wind turbines (AWTs) represent a radically new and fascinating concept for future harnessing of wind power. This concept consists of realizing only the blades of a conventional wind turbine (CWT) in the form of a power kite flying at high speed perpendicular to the wind. On the kite are mounted a turbine, an electrical generator, and a power electronics converter. The electric power generated is transmitted via a medium voltage cable to the ground. Because of the high flight speed of the power kite, several times the actual wind speed, only a very small swept area of the turbine is required according to Betz's Law and/or a turbine of low weight for the generation of a given electric power. Moreover, because of the high turbine rotational speed, no gear transmission is necessary and the size of the generator is also reduced. For takeoff and landing of the power kite, the turbines act as propellers and the generators as motors, i.e., electric power is supplied so that the system can be maneuvered like a helicopter. In the present work, the configuration of power electronics converters for the implementation of a 100 kW AWT is considered. The major aspect here is the trade-off between power-to-weight ratio (W/kg) and efficiency. The dependence of cable weight and cable losses on the voltage level of power transmission is investigated, and a comparison is made between low voltage (LV) and medium voltage (MV) versions of generators. Furthermore, the interdependence of the weight and efficiency of a bidirectional dual active bridge dc-dc converter for coupling the rectified output voltage of a LV generator to the MV cable is discussed. On the basis of this discussion, the concept offering the best possible compromise of weight and efficiency in the power electronics system is selected and a model of the control behavior is derived for both the power flow directions. A control structure is then proposed and dimensioned. Furthermore, questions of electromagnetic compatibility and electrical safety are treated. In conclusion, the essential results of this paper are summarized, and an outlook on future research is given. To enable the reader to make simplified calculations and a comparison of a CWT with an AWT, the aerodynamic fundamentals of both the systems are summarized in highly simplified form in an Appendix, and numerical values are given for the 100 kW system discussed in this paper.

An Airborne Cycloidal Wind Turbine Mounted Using a Tethered Balloon

This study proposes a design for an airborne wind turbine generator. The proposed system comprises a cycloidal wind turbine adopting a cycloidal rotor blade system that is used at a high altitude. The turbine is mounted on a tethered balloon. The proposed system is relatively easier to be realized and stable. Moreover, the rotor efficiency is high, which can be adjusted using the blade pitch angle variation. In addition, the rotor is well adapted to the wind-flow direction change. This article proves the feasibility of the proposed system through a sample design for a wind turbine that produces a power of 30 kW. The generated wind power at 500 m height is nearly 3 times of that on the ground.