In an example embodiment, a system includes a plurality of drive units coupled to a plurality of propellers. Each drive unit includes a single motor/generator and a single motor controller, and the plurality of drive units includes a first drive-unit pair and a second drive-unit pair. The system also includes a high-voltage bus connecting the motor controllers in the first drive-unit pair to a tether, a low-voltage bus connecting the motor controllers in the second drive-unit pair to the tether, and an intermediate-voltage bus connecting the motor controllers of the first drive-unit pair in series with the motor controllers of the second drive-unit pair. The motor controllers in the first drive-unit pair are connected in parallel via the high-voltage bus and the intermediate-voltage bus, and the motor controllers in the second drive-unit pair are connected in parallel via the intermediate-voltage bus and the low-voltage bus.

A fault gas detection system for a liquid filled high voltage transformer, the transformer including a main tank and an expansion tank the tanks fluidic connected by an exchange conduit such that gas and/or a transformer liquid is able to exchange between the tanks, the gas detection system including: a chamber with a top cover, a predefined horizontal level-plane in the chamber defining a maximum liquid level of a transformer liquid in the chamber during use, a fluid-channel including a fluid-egress at a level equal to or higher than the top cover and a fluid-ingress lower than the level of the level-plane, a level sensor designed to measuring and/or indicating a liquid level. A respective transformer and a respective wind turbine system is also provided.

A motor control topology relevant to airborne wind turbines and a control process for such a motor control topology is disclosed herein.

An underwater flow turbine includes a gondola having an interior, a generator in the gondola interior, a rotatable hub connected to the gondola and configured to support a plurality of rotor blades, the rotatable hub being operatively connected to the generator, and an air handling device, such as a fan or an air filtration system, in the gondola and/or in the hub.

A motor control topology relevant to airborne wind turbines and a control process for such a motor control topology is disclosed herein. A system may include an aerial vehicle that may include a plurality of propellers, a plurality of drive units coupled to the plurality of propellers, and a tether. Each drive unit may include a motor/generator and a motor controller. The plurality of drive units may include at least two pairs of drive units that include a first drive-unit pair and a second drive-unit pair. The drive units in each drive pair may be connected in parallel, and the at least two pairs of drive units may be connected in series. The drive units may be configured to operate in a first mode and operate in a second mode.

A method for black starting a wind turbine and a wind farm following islanding operation, a method for restoring the wind farm following the islanding operation, and the wind turbine and wind farm. The wind turbine comprises auxiliary equipment, a generator, a converter electrically connectable to the generator, and an energy storage system, the generator is electrically connectable to the auxiliary equipment via the converter, the energy storage system is electrically connectable to the auxiliary equipment. The method for black staring the wind turbine including: measuring wind blowing smoothness degree; selecting a first power source to supply first power to the auxiliary equipment in V/f control mode and selecting a second power source to adjust an amount of active power and reactive power fed to the auxiliary equipment by the first power source in consideration of the amount of active power and reactive power demand suitable for powering the auxiliary equipment; and connecting the power sources to the auxiliary equipment.

The invention relates to a method for controlling a wind power installation which has a rotor having rotor blades that are adjustable in terms of their blade angle, and having a rotor diameter, wherein the rotor is able to be operated at a variable rotor rotating speed; and a region in which the rotor blades move forms a danger zone for birds and bats, the method comprising the following steps: checking whether a bird or bat approaching the wind power installation is an endangered bird and if an endangered bird has been identified, detecting a bird position as the current position of the endangered bird identified; and controlling the rotor rotating speed as a function of the bird position in relation to the wind power installation; wherein the rotor rotating speed is reduced in multiple stages or continuously as the distance of the bird position from the wind power installation decreases. The invention is intended to propose a solution in which a wind power installation poses the lowest possible risk to endangered species of birds and bats while at the same time offering the best possible yield. The intention is to at least propose an alternative to the solutions known to date.

There is presented a method 310 for controlling a rotor 102 on a wind turbine 100, wherein the rotor is comprising one or more blades 103, and wherein the wind turbine is comprising a pitch system, the method comprising: Operating 312 the rotor in a standstill or idling operating state, determining or receiving 314 one or more control parameters, where the control parameters enable determining one or more yawing parameters may be described as a function of the one or more control parameters, wherein the one or more yawing parameters comprises one or more of: An angular yawing velocity of the a yawing section, an angular yawing acceleration of the yawing section, and/or a yawing moment applied by the yawing section on a remainder of the wind turbine, and pitching 316 based on the one or more control parameters one or more blades 103 of the rotor 100 with the pitch system.

A safety system of a wind turbine system is provided. The wind turbine system includes at least one wind turbine and a hydrogen production system configured to produce hydrogen using electrical power generated by the wind turbine. The safety system include a monitoring system configured to monitor the wind turbine system to detect a malfunction of the hydrogen production system. It further includes a control system configured to trigger a safety function of the wind turbine system upon detection of a malfunction of the hydrogen production system by the monitoring system.

An underwater flow turbine includes a gondola having an interior, a generator in the gondola interior, a rotatable hub connected to the gondola and configured to support a plurality of rotor blades, the rotatable hub being operatively connected to the generator, and an air handling device, such as a fan or an air filtration system, in the gondola and/or in the hub.