Abstract: A wind turbine cooling system comprising a cooling circuit arranged to convey a cooling fluid to and from a heat source, a cooling device arranged to cool the cooling fluid, a 5 pump arranged to circulate the cooling fluid in the cooling circuit, and a cooling fluid tank arranged in fluid connection with the cooling circuit and having a first fluid port adjacent a top of the tank and a second fluid port adjacent a bottom of the tank, wherein the second fluid port is arranged to communicate with the cooling circuit, wherein the pump has an outlet arranged in fluid connection with the cooling circuit and in fluid 10 connection with the tank, and wherein a fluid path between the pump outlet and the tank includes a flow restriction device.

Abstract: The invention relates to a method for controlling a wind turbine system, more particular for a controlled sliding strategy to lower loads on the yaw system by controlling mechanical brakes and motor brakes in the yaw drive actuators. When the yaw system being in the non-yawing operational state, and the mechanical brake(s) being in an engaged state, and the yaw controller determines or receives a signal indicative of a yaw moment, and if the signal indicative of a yaw moment is above a signal threshold, then the yaw controller sends a braking signal to the yaw drive actuators to enter the motors into the brake state to apply a braking torque.

Abstract: The invention relates to a method for monitoring yawing fault events of a yaw system of a wind turbine. The yaw system comprises one or more actuators for driving the yaw system and a holding system to resist yaw rotation. The yaw system is arranged to provide yaw rotation in response to a yaw control signal. According to the method, the monitored yaw angle is compared with the yaw control signal, and based on the comparison, a correlation between a monitored change in the yaw angle and the yaw control signal is determined. A yawing fault event is determined dependent on the determined correlation.

Abstract: A wind turbine cooling system comprising a cooling circuit arranged to convey a cooling fluid to and from a heat source, a cooling device arranged to cool the cooling fluid, a 5 pump arranged to circulate the cooling fluid in the cooling circuit, and a cooling fluid tank arranged in fluid connection with the cooling circuit and having a first fluid port adjacent a top of the tank and a second fluid port adjacent a bottom of the tank, wherein the second fluid port is arranged to communicate with the cooling circuit, wherein the pump has an outlet arranged in fluid connection with the cooling circuit and in fluid 10 connection with the tank, and wherein a fluid path between the pump outlet and the tank includes a flow restriction device.

Abstract: Techniques for determining the presence of ice at a wind farm with a number of wind turbines. The controller receives a current ambient temperature of the wind farm. The controller also receives a measured current wind speed from wind speed sensors of the wind turbines. The controller also receives an estimated current wind speed of each of the wind turbines that is based on measured performance parameters of the associated wind turbine. The controller determines a current wind speed difference between the measured current wind speed and the estimated current wind speed for each of the wind turbines, and determines a current delta distribution based on the current wind speed differences. The controller also determines whether an ice event has occurred, the determination being in dependence on the current ambient temperature and in dependence on the current delta distribution, and then outputs an outcome of the ice event determination.

Abstract: Assessing performance impact of a power upgrade of one or more wind turbines of a wind farm that includes a group of target wind turbines and a group of reference wind turbines. For each of the target wind turbines, a transfer function is generated, establishing a relationship between the locally measured wind speed at the target wind turbine and locally measured wind speeds at each of the reference wind turbines. A power upgrade is performed on each of the target wind turbines, and subsequently power performance data is obtained for the reference wind turbines and the target wind turbines, within one or more wind speed intervals. For the target wind turbines, the wind speed intervals are based on estimated wind speeds, based on locally measured wind speeds at the reference wind turbines and the transfer functions.

Abstract: Monitoring and assessing power performance changes of one or more wind turbines of a wind farm. For each wind turbine to be monitored, a group of reference wind turbines is defined. During a training period a transfer function is generated for each monitored wind turbine. The transfer function establishes a relationship between locally measured wind speeds at each of the reference wind turbines and the power performance data for the monitored wind turbine obtained during the training period. During one or more subsequent test periods, measured power performance data for the monitored wind turbines is compared to predicted power performance data. The predicted power performance data is obtained by means of the locally measured wind speeds at the corresponding reference wind turbines during the test period(s) and the previously generated transfer function for the monitored wind turbine. This allows even small and/or gradual power performance degradation to be detected.

Abstract: A method for monitoring and assessing power performance changes of one or more wind turbines of a wind farm, the method comprising the steps of: for each wind turbine to be monitored, defining a group of reference wind turbines, the group of reference wind turbines comprising two or more wind turbines, operating the wind turbines of the wind farm, while obtaining locally measured wind speeds at each of the wind turbines, during a training period, obtaining the power performance data in relation to the locally measured wind speed for each of the monitored wind turbines, during the training period, for each of the monitored wind turbines, generating a wind speed transfer function establishing a relationship between the locally measured wind speeds at each of the reference wind turbines and the locally measured wind speed at the monitored wind turbine, operating the wind turbines of the wind farm, while obtaining locally measured wind speeds, at least at the reference wind turbines during one or more test period

Abstract: A method for monitoring and assessing power performance changes of one or more wind turbines of a wind farm, the method comprising the steps of: for each wind turbine to be monitored, defining a group of reference wind turbines, the group of reference wind turbines comprising two or more wind turbines, operating the wind turbines of the wind farm, while obtaining locally measured wind speeds at each of the wind turbines, during a training period, obtaining the power performance data in relation to the locally measured wind speed for each of the monitored wind turbines, during the training period, for each of the monitored wind turbines, generating a wind speed transfer function establishing a relationship between the locally measured wind speeds at each of the reference wind turbines and the locally measured wind speed at the monitored wind turbine, operating the wind turbines of the wind farm, while obtaining locally measured wind speeds, at least at the reference wind turbines during one or more test period

Abstract: Monitoring and assessing power performance changes of one or more wind turbines of a wind farm. For each wind turbine to be monitored, a group of reference wind turbines is defined. During a training period a transfer function is generated for each monitored wind turbine. The transfer function establishes a relationship between locally measured wind speeds at each of the reference wind turbines and the power performance data for the monitored wind turbine obtained during the training period. During one or more subsequent test periods, measured power performance data for the monitored wind turbines is compared to predicted power performance data. The predicted power performance data is obtained by means of the locally measured wind speeds at the corresponding reference wind turbines during the test period(s) and the previously generated transfer function for the monitored wind turbine. This allows even small and/or gradual power performance degradation to be detected.

Abstract: Assessing performance impact of a power upgrade of one or more wind turbines of a wind farm that includes a group of target wind turbines and a group of reference wind turbines. For each of the target wind turbines, a transfer function is generated, establishing a relationship between the locally measured wind speed at the target wind turbine and locally measured wind speeds at each of the reference wind turbines. A power upgrade is performed on each of the target wind turbines, and subsequently power performance data is obtained for the reference wind turbines and the target wind turbines, within one or more wind speed intervals. For the target wind turbines, the wind speed intervals are based on estimated wind speeds, based on locally measured wind speeds at the reference wind turbines and the transfer functions.

Abstract: An electrical connector (30) is described for providing power between a nacelle (14) and a hub (16) of a wind turbine (10). The electrical connector includes a first electrical connector part (32) for connection to one of the nacelle or the hub, and a second electrical connector (34) part for connection to the other of the nacelle or the hub. The electrical connector further includes an actuator (46) for moving the first or second electrical connector parts in a first direction between an extended position in which the first and second connector parts are in contact and form an electrical connection between the nacelle and the hub, and a retracted position in which the first and second electrical connector parts are spaced apart and do not form an electrical connection. The first and/or second electrical connector parts include one or more magnets (84) arranged to secure the first and second parts together when the respective parts are in contact.

Abstract: A wind turbine blade ice accretion detector 65 is configured to receive an indication of power generated by a wind turbine 67 and an indication of a plurality of environmental conditions of the wind turbine 69. It is also configured to receive an indication of an error relating to the operation of the wind turbine 71. These indications are processed by the detector 65 to provide an indication of ice accretion of a wind turbine blade. In addition to or as an alternative, the wind turbine blade ice accretion detector 65 is configured to receive an indication of power generated by a wind turbine 67 in a plurality of different time periods and an indication of a plurality of environmental conditions of the wind turbine 69 in the plurality of different time periods; and to process these to provide an indication of ice accretion of a wind turbine blade.