Abstract: A method and a system for managing loads on a wind turbine are provided. The method includes receiving a signal relative to a yaw misalignment of the wind turbine, generating a yaw error signal based on the yaw misalignment, and comparing the yaw error signal to a first predetermined yaw error threshold value. The method also includes regulating a speed of the rotor to a value determined by a predetermined tip speed ratio, reducing the yaw misalignment using a yaw control system, and restarting the wind turbine if the yaw error signal is reduced to less than a second predetermined yaw error threshold value within a predetermined period of time. The method further includes shutting down the wind turbine if the yaw error signal remains greater than the second predetermined yaw error threshold value beyond the predetermined period of time.

Abstract: Systems and methods for monitoring wind turbine loading are provided. In one embodiment, a system includes a main shaft, a bedplate, and a gearbox coupled to the main shaft and mounted to the bedplate. The gearbox includes an outer casing and a torque arm extending from the outer casing. The system further includes an isolation mount coupled to the torque arm, and a sensor configured to measure displacement of the torque arm. In another embodiment, a method includes operating the wind turbine, and detecting displacement of a torque arm of a gearbox of the wind turbine. The method further includes calculating a moment for a main shaft of the wind turbine based on the displacement of the torque arm.

Abstract: Systems and methods to reduce tower oscillations in a wind turbine are presented. The method includes obtaining a rotor velocity. Furthermore, the method includes obtaining one or more parameters associated with a tower of the wind turbine. Further, the method includes determining a modified rotor velocity based on the one or more parameters. Moreover, the method includes determining a first pitch angle based on the modified rotor velocity. In addition, the method includes pitching one or more blades of the wind turbine based on the first pitch angle to reduce the tower oscillations.

Abstract: Methods are provided for controlling wind turbine loading. In one embodiment, a method includes the steps of determining a current thrust value for the wind turbine, calculating a thrust differential based on the current thrust value and a predetermined maximum thrust value, calculating a desired pitch offset value based on the thrust differential and a thrust sensitivity value, and adjusting a pitch of the wind turbine utilizing the pitch offset value.

Abstract: A control system for mitigating loads on a wind turbine comprising a plurality of blades in yaw error events includes a yaw error calculation unit for calculating a yaw error of the wind turbine, a pitch angle reference command calculation unit for calculating a plurality of pitch angle reference commands respectively corresponding to the plurality of blades at least based on the calculated yaw error, and a controller for producing a plurality of pitch commands at least based on the plurality of pitch angle reference commands, to respectively regulate the pitch angles of the plurality of blades.

Abstract: A method and a system for managing loads on a wind turbine are provided. The method includes receiving a signal relative to a yaw misalignment of the wind turbine, generating a yaw error signal based on the yaw misalignment, and comparing the yaw error signal to a first predetermined yaw error threshold value. The method also includes regulating a speed of the rotor to a value determined by a predetermined tip speed ratio, reducing the yaw misalignment using a yaw control system, and restarting the wind turbine if the yaw error signal is reduced to less than a second predetermined yaw error threshold value within a predetermined period of time. The method further includes shutting down the wind turbine if the yaw error signal remains greater than the second predetermined yaw error threshold value beyond the predetermined period of time.

Abstract: Systems and methods for monitoring wind turbine loading are provided. In one embodiment, a system includes a main shaft, a bedplate, and a gearbox coupled to the main shaft and mounted to the bedplate. The gearbox includes an outer casing and a torque arm extending from the outer casing. The system further includes an isolation mount coupled to the torque arm, and a sensor configured to measure displacement of the torque arm. In another embodiment, a method includes operating the wind turbine, and detecting displacement of a torque arm of a gearbox of the wind turbine. The method further includes calculating a moment for a main shaft of the wind turbine based on the displacement of the torque arm.

Abstract: Methods are provided for controlling wind turbine loading. In one embodiment, a method includes the steps of determining a current thrust value for the wind turbine, calculating a thrust differential based on the current thrust value and a predetermined maximum thrust value, calculating a desired pitch offset value based on the thrust differential and a thrust sensitivity value, and adjusting a pitch of the wind turbine utilizing the pitch offset value.

Abstract: Wind turbines and methods for controlling wind turbine loading are provided. In one embodiment, a method includes the steps of determining a current wind speed. The method further includes determining a tip speed ratio and a pitch angle that maximize a power coefficient under at least one of the following conditions: a thrust value is less than or equal to a pre-established maximum thrust, a generator speed value is less than or equal to a pre-established maximum generator speed, or a generator torque is less than or equal to a pre-established maximum generator torque. The method further includes calculating a desired generator speed value based on the current wind speed and a tip speed ratio. The method further includes calculating a desired generator power value based on the desired generator speed value.

Abstract: A level control system for controlling a liquid level in a vessel containing a two-phase fluid includes a plurality of sensors configured to measure parameters related to the vessel. The parameters include liquid level in the vessel, vapor flow rate leaving the vessel, pressure in the vessel, temperature of the vessel, and feed-liquid flow rate entering the vessel indicative of a state of the vessel. A predictive controller is configured to receive output signals from the plurality of sensors and predict a volume of liquid over a predetermined time period in the vessel based on output signals from the plurality of sensors and a variation in pressure, thermal load, or combinations thereof in the vessel. The controller is configured to generate a liquid level set point of the vessel based on the predicted volume of liquid in the vessel; and further control a liquid level in the vessel based on the generated liquid level set point by manipulating one or more control elements coupled to the vessel.

Abstract: A control system for mitigating loads on a wind turbine comprising a plurality of blades in yaw error events includes a yaw error calculation unit for calculating a yaw error of the wind turbine, a pitch angle reference command calculation unit for calculating a plurality of pitch angle reference commands respectively corresponding to the plurality of blades at least based on the calculated yaw error, and a controller for producing a plurality of pitch commands at least based on the plurality of pitch angle reference commands, to respectively regulate the pitch angles of the plurality of blades.

Abstract: Systems and methods to reduce tower oscillations in a wind turbine are presented. The method includes obtaining a rotor velocity. Furthermore, the method includes obtaining one or more parameters associated with a tower of the wind turbine. Further, the method includes determining a modified rotor velocity based on the one or more parameters. Moreover, the method includes determining a first pitch angle based on the modified rotor velocity. In addition, the method includes pitching one or more blades of the wind turbine based on the first pitch angle to reduce the tower oscillations.

Abstract: Techniques for operating a wind turbine are described herein. In an example, a wind turbine includes a tower, a nacelle coupled to the tower, a rotor rotatably coupled to the nacelle, at least one blade coupled to the rotor and configured to rotate about a pitch axis, and a controller to operate the wind turbine based on predicted wind speed values. The controller includes a twist determination module to determine a blade-twist value, wherein the blade-twist value is indicative of an actual blade-twist of a rotor blade during operation of the wind turbine. The controller may further include a wind speed determination module to determine at least one wind speed value indicative of a wind speed using the blade-twist value.

Abstract: A control system for providing an optimal estimate of NOx emission in an exhaust during a selective catalytic reduction process is provided. The control system includes a continuous emission monitoring sensor configured to generate a responsive signal representing a first estimate of NOx emission; wherein the responsive signal has a first time lag between a time of measurement of NOx emission and the time when the corresponding responsive signal is made available by the continuous emission monitoring sensor, and the continuous emission monitoring sensor has a first time constant. The control system also includes a virtual sensor configured to generate a relatively faster responsive signal representing a second estimate of NOx emission. The control system further includes a processor that includes a time delay compensation circuit configured to introduce a second time lag in the relatively faster responsive signal, wherein the second time lag matches the first time lag.

Abstract: A system for determining wind turbine tower base torque loads including a controller configured to determine a torque load of a base of a tower of a wind turbine according to a computation of an effective height of the wind turbine multiplied by a wind force upon a rotor of the wind turbine, and generate a control signal representing the torque load. A method for determining wind turbine tower base torque loads including determining a torque load of a base of a tower of a wind turbine according to the foregoing computation, and generating a control signal representing the torque load.

Abstract: A system includes sensors configured to measure vessel parameters. A signal processing unit receives sensor output signals and generates a first, second, third, fourth, and fifth filtered output signals representative of liquid level, gas flow rate, feed-liquid flow rate, vessel pressure, and vessel temperature, respectively. A flow demand control unit receives the first filtered output signal and generates an output signal representative of feed-liquid flow demand. A shaping unit receives the second, fourth, and fifth filtered output signals and generates an output signal representative of shaped gas flow rate. A liquid level control unit controls the liquid level within predetermined limits by controlling one or more components based on the output signals from the flow demand control unit, the shaping unit, and the third filtered output signal.

Abstract: A control system for providing an optimal estimate of NOx emission in an exhaust during a selective catalytic reduction process is provided. The control system includes a continuous emission monitoring sensor configured to generate a responsive signal representing a first estimate of NOx emission; wherein the responsive signal has a first time lag between a time of measurement of NOx emission and the time when the corresponding responsive signal is made available by the continuous emission monitoring sensor, and the continuous emission monitoring sensor has a first time constant. The control system also includes a virtual sensor configured to generate a relatively faster responsive signal representing a second estimate of NOx emission. The control system further includes a processor that includes a time delay compensation circuit configured to introduce a second time lag in the relatively faster responsive signal, wherein the second time lag matches the first time lag.

Abstract: A level control system for controlling a liquid level in a vessel containing a two-phase fluid includes a plurality of sensors configured to measure parameters related to the vessel. The parameters include liquid level in the vessel, vapor flow rate leaving the vessel, pressure in the vessel, temperature of the vessel, and feed-liquid flow rate entering the vessel indicative of a state of the vessel. A predictive controller is configured to receive output signals from the plurality of sensors and predict a volume of liquid over a predetermined time period in the vessel based on output signals from the plurality of sensors and a variation in pressure, thermal load, or combinations thereof in the vessel. The controller is configured to generate a liquid level set point of the vessel based on the predicted volume of liquid in the vessel; and further control a liquid level in the vessel based on the generated liquid level set point by manipulating one or more control elements coupled to the vessel.

Abstract: An apparatus and method for controlling a wind turbine having a plurality of blades such that the blade angle of each blade is continuously adjusted during loss of grid power relative to a wind direction relative to an orientation of the nacelle (i.e., yaw offset) and a rotor azimuth while keeping the orientation of the nacelle of the wind turbine substantially constant. The wind turbine is capable of pitching the blades a full 360 degrees and generating power from the rotation of the rotor shaft during loss of grid power.

Abstract: An apparatus and method for controlling a wind turbine having a plurality of blades such that the blade angle of each blade is continuously adjusted during loss of grid power relative to a wind direction relative to an orientation of the nacelle (i.e., yaw offset) and a rotor azimuth while keeping the orientation of the nacelle of the wind turbine substantially constant. The wind turbine is capable of pitching the blades a full 360 degrees and generating power from the rotation of the rotor shaft during loss of grid power.