Embodiments of the present invention provide methods and apparatus for increasing turbulent mixing in the wake of at least one wind turbine. Doing so, increases efficiency of a wind turbine located in the wake by transferring energy to the wake that was lost when the wind passed through the upwind turbine. Turbulent mixing may be increased by changing the induction factor for a rotor by, for example, altering the pitch of the blades, the RPMs of the rotor, or the yaw of the nacelle. These techniques may be static or dynamically changing. Further, the different induction factors for a plurality of wind turbines may be synchronized according to a predetermined pattern to further increase turbulent mixing.

A method for controlling a converter, preferably a generator-side active rectifier of a power converter of a wind power installation, comprising: specifying a target value for the converter; specifying a carrier signal for the converter; capturing an actual value; determining a distortion variable from the target value and the actual value; and determining driver signals for the converter on the basis of the distortion variable and the carrier signal.

A method for controlling a wind turbine may generally include operating the wind turbine at an initial power output that is greater than a rated power output associated with the wind turbine. The wind turbine may have an anticipated operational life at the rated power output. In addition, the method may include decreasing a power output of the wind turbine over time in order to maintain an actual operating life of the wind turbine substantially equal to or greater than the anticipated operational life. A final power output of the wind turbine at an end of the anticipated operating life may be less than the rated power output.

The present application provides a method and a system for controlling continuous high voltage ride-through and low voltage ride-through of a permanent magnet direct-driven wind turbine. The method includes: determining a transient time period during which the wind turbine is transitioned from a high voltage ride-through state to a low voltage ride-through state; controlling the wind turbine to provide, during the transient time period, a gradually increasing active current to the point of common coupling; and controlling the wind turbine to provide, during the transient time period, a reactive current to the point of common coupling according to an operation state of the wind turbine before the high voltage ride-through state.

A method for operating a wind farm having a string (S1-S3) of wind turbines (100-100c) which are electrically connectable with each other and a grid (510, 550) is disclosed. Each wind turbine includes a rotor (106) with rotor blades (108), a power conversion system (118, 210, 238) mechanically connected with the rotor (106), and at least one auxiliary subsystem (105, 109). The method includes operating the wind turbines of the string in an island operating mode in which the wind turbines are not connected with the grid, and the respective at least one auxiliary subsystem is supplied with electric power generated by the power conversion system of the respective wind turbine; detecting that the rotor of one of the wind turbines is exposed to a wind condition at which at least one of the rotor blades is at risk of stalling at the currently generated electric output power; and increasing the electric power generated by the power conversion system of the one of the wind turbines by an electric power amount which is sufficient for suppling the at least one auxiliary subsystem of at least one of the other wind turbines of the string.

A method (1000, 1001) for operating a wind turbine (100-100d) is disclosed. The wind turbine includes a rotor (106) with rotor blades (108), a power conversion system (118, 210, 234) mechanically connected with the rotor (106), a first subsystem (310 ), a second subsystem (320), and an internal electric power distribution system (300-301b, 321, 322) connectable with the first subsystem (310) and the second subsystem (320). During operating (1100) the wind turbine (100-100d) in a normal operating mode in which the power conversion system (118, 210, 234) converts input motive power into electrical output power (P), the method (1000) includes detecting (1200) an increased power demand of the first subsystem (310), and actively increasing (1300) an amount (P1) of electric power (Pint) flowing through the internal electric power distribution system (300-301b, 321, 322) to the first subsystem (310) if a power demand of the second subsystem (320) is at least reduced.

The invention relates to a method for limiting structural loads in a wind turbine in situations where the power produced by the wind turbine is increased or decreased. The limitation of structural loads is achieved by restricting the power ramp rate, i.e. the rate of change of increases or decreases in produced power. The restriction is only invoked if a maximum change of the produced power or the corresponding internal power reference within a time window exceeds a given threshold.

A system and method are provided for controlling low-speed operations of a wind turbine electrically coupled to an electrical grid. The wind turbine includes a generator and a power converter. The generator includes a generator rotor and a generator stator. An operating parameter of the generator rotor is indicative of a low-speed operation of the generator. Accordingly, the crossing of a first threshold by the operating parameter is detected. In response, at least a portion of a required reactive power generation is developed via the generator rotor. The portion is then delivered to the electrical grid via the grid side of the power converter.

The present disclosure is directed to systems and methods for generating one or more farm-level power curves for a wind farm that can be used to validate an upgrade provided to the wind farm. The method includes operating the wind farm in a first operational mode. Another step includes collecting turbine-level operational data from one or more of the wind turbines in the wind farm during the first operational mode. The method also includes aggregating the turbine-level operational data into a representative farm-level time-series. Another step includes analyzing the operational data collected during the first second operational mode. Thus, the method also includes generating one or more farm-level power curves for the first operational mode based on the analyzed operational data.

The present disclosure is directed to a system and method for controlling a wind farm. The method includes operating the wind farm based on multiple control settings over a plurality of time intervals. A next step includes collecting one or more wind parameters of the wind farm over the plurality of time intervals and one or more operating data points for each of the wind turbines in the wind farm for the plurality time intervals. The method also includes calculating a contribution of the operating data points for each of the wind turbines as a function of the one or more wind parameters. Further steps of the method include estimating an energy production for the wind farm for each of the control settings based at least in part on the contribution of the operating data points and controlling the wind farm based on optimal control settings.