Abstract: The present invention relates to controlling a wind turbine with an updated power coefficient. The updated power coefficient being adjusted by a degradation function which is determined in an iterative adjustment process. The wind turbine is controlled in partial load operation mode based on a tip-speed ratio (TSR) tracking scheme based on an estimated wind speed. The iterative adjustment process comprises operating the wind turbine to obtain a measurement set. The degradation function that represents the values of the measurement set is calculated and assigned to the mean operating TSR of the measurement set. The iterative process is continued until a difference between the selected TSR and the mean operating TSR is below a preset difference. A continuous degradation function for a range of the mean operating TSR value(s) is thereby obtained to determine an updated power coefficient to be used as the operating power coefficient.

Abstract: The present invention relates to controlling a wind turbine with a scaled power coefficient where the scaled power coefficient is determined in an adjustment process. In particular is disclosed control of a wind turbine in a partial load operation mode based on a tip-speed ratio (TSR) tracking scheme which based on an estimated wind speed determines a power setpoint. The disclosed adjustment process comprises setting a scaled power coefficient as a predetermined power coefficient multiplied by a scaling factor; adding a time-varying perturbation signal to the power setpoint; determining a transfer function from the perturbation signal to a power error; evaluate the frequency response of the transfer function over a time period to determine the scaling factor which minimizes the gain of the transfer function; and setting the operating power coefficient as the scaled power coefficient.

Abstract: The present invention relates to controlling a wind turbine with an updated power coefficient. The updated power coefficient being adjusted by a degradation function which is determined in an iterative adjustment process. The wind turbine is controlled in partial load operation mode based on a tip-speed ratio (TSR) tracking scheme based on an estimated wind speed. The iterative adjustment process comprises operating the wind turbine to obtain a measurement set. The degradation function that represents the values of the measurement set is calculated and assigned to the mean operating TSR of the measurement set. The iterative process is continued until a difference between the selected TSR and the mean operating TSR is below a preset difference. A continuous degradation function for a range of the mean operating TSR value(s) is thereby obtained to determine an updated power coefficient to be used as the operating power coefficient.

Abstract: The present invention relates to controlling a wind turbine with a scaled power coefficient where the scaled power coefficient is determined in an adjustment process. In particular is disclosed control of a wind turbine in a partial load operation mode based on a tip-speed ratio (TSR) tracking scheme which based on an estimated wind speed determines a power setpoint. The disclosed adjustment process comprises setting a scaled power coefficient as a predetermined power coefficient multiplied by a scaling factor; adding a time-varying perturbation signal to the power setpoint; determining a transfer function from the perturbation signal to a power error; evaluate the frequency response of the transfer function over a time period to determine the scaling factor which minimizes the gain of the transfer function; and setting the operating power coefficient as the scaled power coefficient.

Abstract: The invention relates to a method for controlling a wind turbine during start up, from a non-producing operation mode to a power producing operation mode when limit cycles occur during start-up. Limit cycles are detected when a number of cut-in transitions or a number of cut-out transitions are detected. A cut-in transition is when the wind turbine fails starting up despite having the wind speed or rotor speed normally required to enter a power producing operation mode. A cut-out transition is occurring when the wind turbine is falling out of power producing operation mode after having entered the power producing operation mode.

Abstract: The invention relates to a method for controlling a wind turbine during start up, from a non-producing operation mode to a power producing operation mode when limit cycles occur during start-up. Limit cycles are detected when a number of cut-in transitions or a number of cut-out transitions are detected. A cut-in transition is when the wind turbine fails starting up despite having the wind speed or rotor speed normally required to enter a power producing operation mode. A cut-out transition is occurring when the wind turbine is falling out of power producing operation mode after having entered the power producing operation mode.