To provide a horizontal axis wind turbine capable of reducing flutter, and by extension, reducing the load on the wind turbine, without controlling the yaw, regardless of the direction of the wind relative to the nacelle. When the wind speed is above a specific value, the yaw angle of the nacelle is held constant, the blade pitch angle is controlled according to the yaw angle Y of the wind direction relative to the nacelle, and the rotor is allowed to rotate freely. Even when the yaw angle of the nacelle is held constant, allowing the rotor to rotate freely makes it possible to reduce the load by avoiding flutter.

Horizontal axis wind turbine

The invention relates to a method for operating a wind energy installation, whereby said wind energy installation (10) is especially switched off following the release of a deactivation signal by a safety cut-out device (20) which logically overrides a management system. Said method is improved in that, following a safety cut-out, the wind energy installation (10) is reactivated by means of an operating device (41) which is spatially separated from the wind energy installation (10). The invention further relates to an energy supply system comprising at least one wind energy installation (10), to a safety chain on a wind energy installation, and to a wind energy installation.

Method for operating a wind energy installation

A method of controlling a wind turbine, where a control signal for a controllable parameter of the wind turbine is determined repeatingly at successive time steps, and a control history including respective control values derived from or included in past control signals is stored. These control values stored in the control history are then used to determine an alert parameter for the controllable parameter, the alert parameter being a function of the variations of the control signals over time. The wind turbine is then controlled according to the most recent control signal only if the alert parameter is below an alert threshold, and otherwise according to a modified control strategy. The control method may be performed on pitch reference signals for controlling the individual and/or collective pitch of the blades. The invention further relates to a control system configured to perform the above control method, and a wind turbine comprising such system.

Wind Turbine Control Method

A wind turbine tower load control method. The pitch of the rotor blades is controlled in a conventional manner by a collective command component. An estimator estimates the tower resonant acceleration and the thrice-per-revolution blade imbalance acceleration. Combining logic, connected to the estimated resonant acceleration and to the estimated thrice-per-revolution (3P) acceleration provides a combined pitch modulation to damp the tower resonant motion and the thrice-per-revolution motion using collective modulation. Said pitch modulation is combined with the collective command component to drive the pitch actuators.

Wind turbine damping of tower resonant motion and symmetric blade motion using estimation methods

Embodiments of the invention generally relate to controlling a wind turbine comprising blades attached to a rotor hub for rotation in a rotor plane and a control system for individually pitching the blades relative to the hub. The rotor planes divided into a plurality of predefined section, wherein each section has an associated pitch reference value. A light detection and ranging device may be used to determine expected properties of wind in each respective section of the rotor plane so that the pitch reference value may be adjusted accordingly.

Rotor-sector based control of wind turbines

A wind turbine rotor load control. The pitch of the blades is controlled in a conventional manner by a command component, a rotor blade pitch command signal. A storage contains stored values of a set of moments for various wind speeds. A moment sensor provides a moment signal output. An instantaneous wind speed indicator provides an instantaneous wind speed value output. A conversion logic connected to the moment signal and to the instantaneous wind speed value, provides a calculated pitch modulation command. Combining logic connected to the calculated blade pitch modulation command and to the collective pitch command, provides a combined blade pitch command, which includes compensation for instantaneous moment deviations of the wind turbine.

Kitchener Clark Wilson

Papers

Wind turbine with blade pitch control to compensate for wind shear and wind misalignment