Provided is a method for starting a wind park including plural wind turbines connectable in a collector system connectable to a utility grid, the method including: starting at least one first wind turbine, each being equipped with an utility grid independent energy supply and a grid forming function, to produce electrical energy from wind energy, thereby utilizing the respective grid independent energy supply for starting; performing the grid forming function by the first wind turbine to achieve a reference voltage in the collector system; starting at least one second wind turbine and/or at least one third wind turbine to produce energy by conversion of wind energy, thereby utilizing energy provided in the collector system for starting.

The invention concerns a method for coupling to the grid a hydraulic unit having a synchronous generator, a runner, and wicket gates, the method comprises: a) a step of increasing the flow of water into the runner from a time t.sub.0 to a time t.sub.1 so that the rotation frequency of the rotor of the synchronous generator is, at time t.sub.1 equal to the frequency of the grid; b) a step of closing the circuit breaker at time t.sub.1, step a) further comprises a sub-step a1) executed from a time t.sub.2 to time t.sub.1, wherein the flow of water is adjusted so that, at time t.sub.1, the phase of the synchronous generator is aligned with the grid phase.

A method for starting a farm grid of a wind farm is provided. The energy generation grid has at least one grid connection point connected to an electrical supply grid and the energy generation grid, in a normal operating mode, exchanges electrical power with the electrical supply grid via the grid connection point. The method includes selecting an establishment mode, different than the normal operating mode, if the electrical supply grid has a voltage drop or the energy generation grid is isolated from the electrical supply grid and operating the energy generation grid in the establishment mode. The establishment mode at least one voltage-influencing wind power installation for providing a wind farm grid voltage and at least one current-influencing wind power installation that synchronizes to the energy generation grid voltage. The wind power installations in total provide an electrical power at the level of an inherent need of the grid.

A start control method for wind turbines (102), comprising: a master control determines whether its real-time wind speed reaches a preset start wind speed when a wind speed of at least one wind turbine (102) or anemometer tower in a wind farm reaches or exceeds the preset start wind speed; the master controller updates a corresponding number simulative start times when determining that its real-time wind speed reaches or exceeds the preset start wind speed, and starts the wind turbine (102) when the number of simulative start times reaches a preset count value. The present invention also relates to a master controller, a system, and a central controller for wind turbines (102).

A wind-driven power generation device based on magnetic levitation is provided. The device includes a magnetic levitation structure, a wind fan, a driving fan, and an electric power generator. Since a floating magnet floated above a fixed magnet in the magnetic levitation structure, the rotation friction of the fan shaft of the wind fan can be greatly reduced to stabilize the output electric power of the wind-driven power generation device.

Embodiments herein describe operating a first wind turbine using an auxiliary control system when a high-voltage link coupling a wind park to a grid is not functioning. When using the auxiliary control system, the first wind turbine provides power to a local AC grid which can be used to power auxiliary system in a second wind turbine while the second wind turbine is shutdown. However, when the high-voltage link is functional, the first and second wind turbines provide power to the high-voltage link using a primary control system.

A method for initializing startup of a wind turbine includes measuring a first wind condition at the wind turbine at a first moment in time. The method also includes measuring a second wind condition at the wind turbine at a subsequent, second moment in time. Further, the method includes estimating an acceleration parameter of the wind turbine as a function of the first wind condition and the second wind condition. Moreover, the method includes comparing the acceleration parameter to a predetermined threshold. As such, the method includes initializing a first startup process for the wind turbine when the acceleration parameter is at or below a predetermined threshold. Further, the method includes initializing a second startup process for the wind turbine when the acceleration parameter exceeds a predetermined threshold, the second startup process being faster than the first startup process.

Provided is a method for starting a wind park including plural wind turbines connectable in a collector system connectable to a utility grid, the method including: starting at least one first wind turbine, each being equipped with an utility grid independent energy supply and a grid forming function, to produce electrical energy from wind energy, thereby utilizing the respective grid independent energy supply for starting; performing the grid forming function by the first wind turbine to achieve a reference voltage in the collector system; starting at least one second wind turbine and/or at least one third wind turbine to produce energy by conversion of wind energy, thereby utilizing energy provided in the collector system for starting.

A gas turbine engine for an aircraft comprises a high-pressure (HP) spool comprising an HP compressor and a first electric machine driven by an HP turbine, the first electric machine having a first maximum output power; a low-pressure (LP) spool comprising an LP compressor and a second electric machine driven by an LP turbine, the second electric machine having a second maximum output power; a combustion system comprising a fuel metering unit; and an engine controller configured to identify a condition to the effect that the engine is in a maximum take-off mode of operation or a maximum climb mode of operation, and, in response to an electrical power demand being between zero and the second maximum output power, only extracting electrical power from the second electric machine to meet the electrical power demand.

There is presented a wind turbine system, wherein the wind turbine system is comprising a support structure, a plurality of wind turbine modules mounted to the support structure wherein each of the plurality of wind turbine modules comprises a rotor, and wherein the wind turbine system further comprises a control system, wherein the control is arranged to execute a wind turbine system transition from a first system operational state of the wind turbine system to a second system operational state of the wind turbine system, and wherein the wind turbine system transition is performed by executing a plurality of wind turbine module transitions from a first module operational state of a wind turbine module to a second module operational state of the wind turbine module wherein the plurality of wind turbine module transitions are distributed in time with respect to each other.