A method (1000-1001) for operating a wind turbine (100) including a rotor (106) having rotor blades (108) and a power conversion system (118, 210, 234) mechanically connected with the rotor (106), configured to convert input motive power into electrical output power, and electrically connected to a network (242) for feeding the electrical output power (P) to the network is provided. The method includes determining (1100) a current frequency (f) of the network (242), and, when the current frequency (f) is equal to or lower than a threshold frequency (f.sub.thresh), operating (1300) the power conversion system (118, 210, 234) at an electrical output power (P) which is increased by an electrical output power increase (PI) in accordance with a monotonic function (PI(f)) of the current frequency (f) limited to a maximum value (PI.sub.max).

A method (2000) for operating a wind turbine (100) including a rotor (106) having rotor blades (108) and a power conversion system (118, 210, 234) mechanically connected with the rotor (106), configured to convert input motive power into electrical output power, and electrically connected to a network (242) for feeding the electrical output power (P) to the network is provided. The method includes initializing (2000), at a first time (t.sub.0), the wind turbine to operate in an overproduction operating mode in which the electrical output power (P(t)) of the power conversion system is increased from an initial electrical output power of the power conversion system by providing kinetic energy stored in the rotor. At a second time (t.sub.2), decreasing (2200) the electrical output power, and integrating a reference power (P.sub.ref, P.sub.0) to determine an energy recovery value (E.sub.rec) are started. An energy response value (E.sub.resp) corresponding to a product of the reference power (P.sub.ref) with a time difference (T.sub.resp) between the second time and the first time is determined (2300). The wind turbine is operated (2400) in a recovery operating mode from a third time (t.sub.3) at which the electrical output power (P) reaches or crosses the reference power (P.sub.ref, P.sub.0) until the energy recovery value becomes at least equal to the energy response value or until the electrical output power reaches or crosses the reference power again from below. In the recovery operating mode, the electrical output power is, limited upwards depending on the reference power and a currently available maximum electrical power output without reducing a speed of the rotor.

Provided is an apparatus and method for cooperative controlling wind turbines of a wind farm, wherein the wind farm includes at least one pair of turbines aligned along a common axis approximately parallel to a current wind direction and having an upstream turbine and a downstream turbine. The method includes the steps of: a) providing a data driven model trained with a machine learning method and stored in a database, b) determining a decision parameter for controlling at least one of the upstream turbine and the downstream turbine by feeding the data driven model with the current power production of the upstream turbine which returns a prediction value indicating whether the downstream turbine will be affected by wake, and/or the temporal evolvement of the current power production of the upstream turbine; c) based on the decision parameter, determining control parameters for the upstream turbine and/or the downstream turbine.

A bearing protection arrangement of a journal bearing arranged between a housing and a rotary component of a wind turbine. The bearing protection arrangement includes a wind speed monitor arranged to monitor wind speed in the vicinity of the wind turbine and to generate a wake-up signal when the wind speed exceeds a pre-defined minimum; a mode switch module of a backup battery arranged to provide restart power to an auxiliary of the wind turbine, which mode switch module is adapted to switch the backup battery from a normal-power mode into a low-power mode to conserve sufficient restart power after low wind-speed conditions, and to switch the backup battery from the low-power mode into a normal-power mode in response to the wake-up signal. A wind turbine and a method of protecting a journal bearing of a wind turbine during standstill.

Provided is a wind power generation system including: a wind power generation apparatus that includes at least a duct having a longitudinal cross section formed in a substantial streamline shape, the longitudinal cross section being cut along a central axis, an impeller placed in the duct, and a power generator that generates power by rotation of the impeller; an anemovane installed so as to be able to measure a wind direction and/or wind power in a vicinity of the wind power generation apparatus; a rotating pedestal that supports the wind power generation apparatus so as to be rotatable along a supporting surface; and a control device that controls a rotational angle of the rotating pedestal based on the wind direction and/or the wind power measured by the anemovane.

An aquifer storage and recovery system can include a pump, an electric motor coupled to the pump, a drive unit configured to control operation of the electric motor, and a controller. The controller can be configured to flow water into a well bore from a source reservoir through the pump such that the pump rotates in a reverse direction and drives the electric motor coupled to the pump in the reverse direction to operate as a generator, determine a power output of the electric motor, determine a difference between the power output of the electric motor and a power output set point, and operate the drive unit to control a rotational speed of the electric motor based at least in part on the difference between the power output of the electric motor and the power output set point.

A system and method are provided for operating a wind farm. Accordingly, a wind direction affecting the wind farm is determined. Based on the wind direction, a controller identifies a turbine cluster, which is a subset of a plurality of wind turbines of the wind farm. The subset includes at least an upwind turbine and a downwind turbine that is affected by a wake emanating from the upwind turbine. With the turbine cluster identified for the given wind direction, the controller then determines a difference between a freestream maximal cluster power output and a wake-affected cluster power output for the turbine cluster. The controller then determines a mitigation setpoint combination for the subset of wind turbines. The mitigation setpoint combination is configured to establish a mitigated cluster power output. Mitigated cluster power output has a difference from the freestream maximal cluster power output that is less than the difference between the freestream maximal cluster power output in the wake-affected cluster power output for the turbine cluster. Based on the mitigation setpoint combination, an operating state of at least one wind turbine of the turbine cluster is changed.

The present disclosure provides a method and an apparatus for self-adaption of a cut-out strategy. The method may include: predicting, using a wind speed prediction model, a wind resource parameter of a wind turbine at each machine location; predicting, using a load prediction model, a fatigue load and a limit load of the wind turbine based on the predicted wind resource parameter and an air density; comparing the predicted fatigue load and limit load with a reference load; and determining the cut-out strategy based on a result of the comparison, wherein determining the cut-out strategy includes determining a cut-out wind speed and an output power.

A method for controlling a power output of a power generating unit is disclosed. An accumulated power output of the power generating unit during a predefined time interval is forecasted. An actual power output of the power generating unit is measured during the predefined time interval, and an actual accumulated power output is estimated for the predefined time interval on the basis of the measured actual power output of the power generating unit. A difference between the forecasted accumulated power output and the estimated actual accumulated power output is derived. The power output of the power generating unit is boosted, in the case that the estimated actual accumulated power output is below the forecasted accumulated power output, and the difference between the forecasted accumulated power output and the estimated actual accumulated power output is larger than a predefined threshold value.

A method for operating a generator of a wind turbine includes generating, via a controller, a time series of a plurality of operating signals of the generator. The method also includes applying at least one algorithm to the time series of the plurality of operating signals of the generator to generate a processed time series of the of the plurality of operating signals of the generator. Moreover, the method includes identifying, via the controller, patterns in the processed time series of the plurality of operating signals of the generator to identify one or more of at least one slip event occurring in the slip coupling or a surface health of the slip coupling. Further, the method includes implementing, via the controller, a control action when the at least one slip event occurring in the slip coupling is identified or the surface health of the slip coupling is indicative of degradation in the slip coupling.