Abstract: Disclosed herein are systems and methods related to electric power transfer between an aerial vehicle of an airborne wind turbine and a power grid. An example power conversion system may include power converters, a DC bus connecting the power converters to the aerial vehicle, and an AC bus connecting the power converters to the power grid. The power converters may be configured to provide AC/DC power conversion between the aerial vehicle and the power grid. The power conversion system may also include switches operable to either (i) electrically connect a respective power converter to the DC bus or electrically isolate the respective power converter from the DC bus. The power conversion system may also include one or more power supplies that can be connected to the DC bus to provide backup power in the event a power converter or the power grid malfunctions.

Abstract: Disclosed herein are systems and methods related to electric power transfer between an aerial vehicle of an airborne wind turbine and a power grid. An example power conversion system may include power converters, a DC bus connecting the power converters to the aerial vehicle, and an AC bus connecting the power converters to the power grid. The power converters may be configured to provide AC/DC power conversion between the aerial vehicle and the power grid. The power conversion system may also include switches operable to either (i) electrically connect a respective power converter to the DC bus or electrically isolate the respective power converter from the DC bus. The power conversion system may also include one or more power supplies that can be connected to the DC bus to provide backup power in the event a power converter or the power grid malfunctions.

Abstract: This disclosure discusses systems and methods related to the following example scenarios. When an aerial vehicle of an airborne wind turbine is functioning normally in motoring mode, a voltage converter may receive a nominal voltage from a power conversion system and provide the nominal voltage to the aerial vehicle. When the aerial vehicle is experiencing a fault in motoring mode, the voltage converter may receive the nominal voltage and provide a reduced fault voltage to the aerial vehicle. When the aerial vehicle is functioning normally in power-generating mode, the voltage converter may receive the nominal voltage from the aerial vehicle and provide the nominal voltage to the power conversion system. When the aerial vehicle is experiencing a fault in power-generating mode, the voltage converter may receive a reduced fault voltage from the aerial vehicle, boost the fault voltage, and provide the boosted fault voltage to the power conversion system.

Abstract: A tether may include a core, a plurality of electrical conductors wound around the core, and a jacket surrounding the plurality of electrical conductors. The plurality of electrical conductors may include at least two groups of electrical conductors. Each group of electrical conductors of the at least two groups of electrical conductors may define a respective electrical path, where the respective electrical path is different from the electrical paths defined by other groups of electrical conductors of the at least two groups of the electrical conductors. Moreover, each group of electrical conductors of the at least two groups of electrical conductors is located around a respective portion of the core, such that a cross-section of each group of electrical conductors of the at least two or more electrical conductors defines a respective arc around the respective portion of the core.

Abstract: Embodiments described herein may relate to power-line communication (PLC) systems that are suitable for high-voltage and electrically noisy applications. In one example system, PLC technology is used to carry data on at least one pair of conductors of a high-voltage (e.g., kilovolt) transmission line that is simultaneously used for power transmission. Further, in some instances, the transmission line may be part of a tether that connects an aerial vehicle to a ground station.

Abstract: In one aspect, a method is described. The method may include operating a plurality of circuit elements, and operating a plurality of fault-mitigation circuits. Each circuit element may include an energy storage element, each individual fault-mitigation circuit may be electrically coupled in parallel to a respective circuit element, and each individual fault-mitigation circuit may include a switch. The method may include detecting an electrical fault in one of the circuit elements and cycling the switch of the fault-mitigation circuit coupled in parallel to the faulty circuit element between an open position and a closed position until the storage element of the faulty circuit element is discharged of energy, at which point the switch remains closed.

Abstract: A method may involve transmitting power between a tethered aerial vehicle equipped with wind turbines for generating power and a ground station configured to interconnect the generated power to an electrical distribution network. The power may be transmitted using high voltage, high frequency AC electrical signals, and transformers at the ground station and the aerial vehicle can scale the AC voltage for use at the respective locations. Converters at the ground station and the aerial vehicle can then convert the transformed voltage to DC. The AC voltage may be transmitted through the tether at a resonant frequency of the tether based in part on an internal capacitance between multiple conductive paths on the tether.

Abstract: A method may involve transmitting power between a tethered aerial vehicle equipped with wind turbines for generating power and a ground station configured to interconnect the generated power to an electrical distribution network. The power may be transmitted using high voltage, high frequency AC electrical signals, and transformers at the ground station and the aerial vehicle can scale the AC voltage for use at the respective locations. Converters at the ground station and the aerial vehicle can then convert the transformed voltage to DC. The AC voltage may be transmitted through the tether at a resonant frequency of the tether based in part on an internal capacitance between multiple conductive paths on the tether.

Abstract: A tether may include a core, a plurality of electrical conductors wound around the core, and a jacket surrounding the plurality of electrical conductors. The plurality of electrical conductors may include at least two groups of electrical conductors. Each group of electrical conductors of the at least two groups of electrical conductors may define a respective electrical path, where the respective electrical path is different from the electrical paths defined by other groups of electrical conductors of the at least two groups of the electrical conductors. Moreover, each group of electrical conductors of the at least two groups of electrical conductors is located around a respective portion of the core, such that a cross-section of each group of electrical conductors of the at least two or more electrical conductors defines a respective arc around the respective portion of the core.

Abstract: A method may involve transmitting power between a tethered aerial vehicle equipped with wind turbines for generating power and a ground station configured to interconnect the generated power to an electrical distribution network. The power may be transmitted using high voltage, high frequency AC electrical signals, and transformers at the ground station and the aerial vehicle can scale the AC voltage for use at the respective locations. Converters at the ground station and the aerial vehicle can then convert the transformed voltage to DC. The AC voltage may be transmitted through the tether at a resonant frequency of the tether based in part on an internal capacitance between multiple conductive paths on the tether.

Abstract: Devices and systems that use an adaptively limited PWM duty-cycle to control a circuit and methods and control programs to operate and to control the devices and systems to adaptively limit the PWM duty-cycle are disclosed. The devices and systems are capable of adjusting the duty-cycle such that the actual inductor current in the next cycle is precisely limited. Specifically, a maximum allowable duty-cycle for time interval N+1 is estimated during time interval N. When the duty-cycle is applied to the circuit at time interval N+1, the peak inductor current is kept below a maximum allowable inductor current level.

Abstract: A circuit for sensing the state of a potentiometer includes a capacitor that is connected to the potentiometer wiper and that is successively charged by applying a voltage to each end of the potentiometer resistive element. The capacitor is discharged between successive chargings. The times needed to charge the capacitor to a predetermined voltage in each case are used to determine the position of the wiper along the resistive element. The circuit can be connected to a plurality of potentiometers, any one of which can be selected and the wiper position determined. A similar circuit can determine the state of an inductive or capacitive voltage divider.