Abstract: Provided is a method of detecting a leak in a hydraulic cylinder of a rotor blade pitch system of a wind turbine including a plurality of rotor blades, which method includes the steps of selecting one of the pitch systems to undergo a functionality test; actuating a fluid pump to move the pistons of the hydraulic cylinders of the pitch systems to their outermost positions; monitoring the hydraulic cylinder pressure levels of the non-selected pitch systems while performing the functionality test on the selected pitch system; and analyzing the monitored hydraulic cylinder pressure levels of the pitch systems to detect a drop in pressure in a pitch cylinder of a non-selected pitch system. A leak detection arrangement of a pitch-controlled wind turbine; and a pitch-controlled wind turbine are also provided.

Abstract: A method of checking a wind turbine in a wind farm with a number of wind turbines for a yaw misalignment is provided. In this method, the yaw angles of at least a subset of wind turbines of the wind farm are ascertained, an average yaw angle is established from the ascertained yaw angles, and a yaw misalignment of the wind turbine to be checked is identified by a deviation of its yaw angle from the average yaw angle by more than a threshold value.

Abstract: A method for detecting changes in a building structure of a first wind turbine is provided. A reference value representing the eigenfrequency of the first wind turbine is monitored over time, whereby substantial changes in the reference value are used as an indication of changes in the building structure. Further, a detection assembly for such detections is provided.

Abstract: A method for detecting changes in a building structure of a first wind turbine is provided. A reference value representing the eigenfrequency of the first wind turbine is monitored over time, whereby substantial changes in the reference value are used as an indication of changes in the building structure. Further, a detection assembly for such detections is provided.

Abstract: A method of checking a wind turbine in a wind farm with a number of wind turbines for a yaw misalignment is provided. In this method, the yaw angles of at least a subset of wind turbines of the wind farm are ascertained, an average yaw angle is established from the ascertained yaw angles, and a yaw misalignment of the wind turbine to be checked is identified by a deviation of its yaw angle from the average yaw angle by more than a threshold value.

Abstract: A method for automated surveillance of at least one wind turbine is provided. A linear model is created or retrieved, which represents at least one status parameter of the wind turbine and which includes a plurality of linear coefficients and a measurement variable. The values of the linear coefficients are determined based on test measurement values for the measurement variable and the status parameter of the wind turbine. Momentary measurement values are repeatedly captured for the measurement variables and the status parameter of the wind turbine. A momentary reference value of the status parameter is determined based on the momentary measurement values for the measurement variables by using the linear model. Wind turbine status information is generated based on the deviation of the momentary measurement value from the corresponding momentary reference value of the status parameter. A monitoring apparatus and a method for creating a linear model are disclosed.