System and method for airborne wind energy production

Abstract

A system for electric power production from wind includes a glider having an airfoil, an on-board steering unit, a flight controller for controlling the steering unit, and a connection unit for a tether. The system further includes a ground station including a reel for the tether, a rotating electrical machine connected to the reel, and a ground station controller for controlling the reel and the rotating electrical machine. A master controller operates the system in at least first and second operation modes. In the first operation mode electric power is produced with the rotating electrical machine from rotation of the reel caused by reeling out the tether using a lift force generated upon exposure of the airfoil of the airborne glider to wind. In the second operation mode, the reel is driven by the rotating electrical machine, thereby reeling in the tether onto the reel.

What is claimed is: 
     
         1 . A system for electric power production from wind comprising a glider, said glider having an airfoil, on-board steering unit for pitching, rolling and yawing the glider when airborne, a flight controller for operation of the steering unit, and a connection unit for a tether, the system further comprising a ground station, said ground station comprising a reel for the tether, a rotating electrical machine connected to the reel, and a ground station controller for operation of the reel and the rotating electrical machine, and the system further comprising a master controller for operation of the system in at least two alternative operation modes, wherein a first operation mode of the system is provided for electric power production with the rotating electrical machine from a rotation of the reel induced by reeling out the tether using a lift force generated upon exposure of the airfoil of the airborne glider to wind, and wherein a second operation mode of the system is provided for system recovery by driving the reel with the rotating electrical machine, thereby reeling in the tether onto the reel. 
     
     
         2 . The system according to  claim 1 , wherein the flight controller provides for a first flight control mode for automated flight operation and for a second flight control mode for manual operation, in particular via a remote control unit with wired or wireless connection to the flight controller. 
     
     
         3 . The system according to  claim 1 , wherein the glider further comprises an air speed sensor for determining an air speed of the glider. 
     
     
         4 . The system according to  claim 1 , wherein the glider comprises a control unit incorporating both the flight controller and the master controller. 
     
     
         5 . The system according to  claim 1 , wherein the ground station further comprises a tension sensor for determining a tension of the tether. 
     
     
         6 . The system according to  claim 1 , wherein the ground station controller is designed for retaining a predetermined target tension of the tether, in particular during reeling out the tether. 
     
     
         7 . The system according to  claim 1 , wherein the ground station controller is designed for retaining a predetermined target reel speed, in particular during reeling in the tether. 
     
     
         8 . The system according to  claim 1 , wherein the tether comprises a power transmission line and/or a data transmission line between the glider and the ground station. 
     
     
         9 . A method for operation of a system for electric power production from wind, said system comprising a glider connected to a tether and a ground station with a reel for the tether, wherein said system is operated alternately in a first operation mode for power production and a second operation mode for system recovery, wherein the first operation mode comprises:
 steering the glider to follow a first flight pattern, thereby generating a lift force via an airfoil of the glider being exposed to the wind,   pulling the tether by said lift force and reeling out the tether, thereby inducing a rotation of the reel, and   converting the rotation of the reel into electric power via a rotating electrical machine connected to the reel,   
       wherein the second operation mode comprises:
 steering the glider to follow a second flight pattern for reduced pull on the tether and 
 reeling in the tether onto the reel by driving the reel via said rotating electrical machine connected to the reel. 
 
     
     
         10 . The method according to  claim 9 , wherein reeling out the tether is controlled to retain a target tension of the tether, which is predetermined as a function of an air speed of the glider. 
     
     
         11 . The method according to  claim 9 , wherein reeling in the tether is controlled to retain a target reel speed, which is predetermined as a function of an air speed of the glider. 
     
     
         12 . A glider that is adapted to be used in a system for electric power production from wind, wherein the system comprises a ground station, said ground station comprising a reel for the tether, a rotating electrical machine connected to the reel, and a ground station controller for operation of the reel and the rotating electrical machine, said glider comprising an airfoil for generating a lift force upon exposure of the airfoil to wind, on-board steering unit for pitching, rolling and yawing the glider when airborne, a flight controller for operation of the steering unit and a connection unit for a tether, wherein the glider comprises an on-board control unit incorporating the flight controller and a master controller for the operation of the system in at least two alternative operation modes;
 wherein a first operation mode of the system is provided for electric power production with the rotating electrical machine from a rotation of the reel induced by reeling out the tether using a lift force generated upon exposure of the airfoil of the airborne glider to wind, and wherein a second operation mode of the system is provided for system recovery by driving the reel with the rotating electrical machine, thereby reeling in the tether onto the reel.