METHOD AND CONTROLLER FOR FULL-POWER CONTROL OF A WIND TURBINE

Abstract

Provided is a method of setting and clearing a full-power flag in a control process running on a wind turbine controller, the method including (a) acquiring a set of measured values and/or reference values for: rotor speed, output power, blade pitch angle, and activation level of an adaptive flow regulating system, (b) determining that a first condition is fulfilled when the value of the rotor speed equals a speed limit value and the output power reference value equals a power limit value, (c) determining when the blade pitch angle reference value fulfills a pitch condition and the activation level of the adaptive flow regulating system fulfills an adaptive flow regulating condition, or when the measured value of the rotor speed is below the speed limit value, (d) setting the full-power flag, and (e) clearing the full-power flag. Furthermore, a wind turbine controller and a wind turbine including such a controller.

Claims

1. A method of setting and clearing a full-power flag in a control process running on a wind turbine controller, the method comprising acquiring a set of measured values and/or reference values for the following parameters: rotor speed, output power, blade pitch angle, and activation level of an adaptive flow regulating system, determining that a first condition is fulfilled when the measured value of the rotor speed equals a speed limit value and the output power reference value equals a power limit value, determining that a second condition is fulfilled when the blade pitch angle reference value fulfills a pitch condition and the activation level of the adaptive flow regulating system fulfills an adaptive flow regulating condition, or when the measured value of the rotor speed is below the speed limit value, setting the full-power flag if the first condition is fulfilled and the second condition has not been fulfilled for a first predetermined period of time, and clearing the full-power flag if the second condition is fulfilled.

2. The method according to claim 1, wherein the pitch condition is fulfilled when a difference between the reference value for the blade pitch angle and a predetermined minimum pitch angle value is below a first pitch threshold value.

3. The method according to claim 1, wherein the pitch condition is fulfilled when an estimate for the time it will take before the reference value for the blade pitch angle reaches the predetermined minimum pitch angle is below a second pitch threshold value.

4. The method according to claim 1, wherein the adaptive flow regulating condition is fulfilled when the reference value for the activation level of the adaptive flow regulating system is below a first flow regulating threshold value.

5. The method according to claim 1, wherein the adaptive flow regulating condition is fulfilled when an estimate for the time it will take before the reference value for the activation level of the adaptive flow regulating system reaches a value corresponding to an inactive adaptive flow regulating system is below a second flow regulating threshold value.

6. The method according to claim 1, wherein the first condition is fulfilled when the measured value of the rotor speed has reached the speed limit value within a second predetermined period of time and the output power reference value has reached the power limit value within a third predetermined period of time.

7. A wind turbine controller comprising a processing unit adapted to perform the method according to claim 1.

8. A wind turbine comprising the wind turbine controller according to claim 7.

Description

BRIEF DESCRIPTION

[0027] Some of the embodiments will be described in detail, with reference to the following FIGURE, wherein like designations denote like members, wherein:

[0028] The FIGURE shows a flow chart of a method according to an embodiment of the present invention.

DETAILED DESCRIPTION

[0029] The illustration in the drawing is schematic. It is noted that in different figures, similar or identical elements are provided with the same reference numerals or with reference numerals which differ only within the first digit.

[0030] When a wind turbine comprises an adaptive flow regulating system, the controller may advantageously take the activation level of the adaptive flow regulating system into consideration for correctly judging if the power can be kept high. This is e.g. possible if blade pitch angle is close to optimal and the adaptive flow regulating system is fully activated, but not if the adaptive flow regulating system is only slightly activated.

[0031] By taking the activation level of the adaptive flow regulating system into account, loss of power production and increase in rotor speed variations can be prevented.

[0032] FIG. 1 shows a flow chart of a method 100 according to an embodiment of the present invention. More specifically, at 110 a set of measured values and/or reference values for the parameters rotor speed, output power, blade pitch angle, and activation level of the adaptive flow regulating system is acquired.

[0033] Then, at 120, it is determined whether a first condition is fulfilled. This is the case when the measured value of the rotor speed equals a speed limit value, and the output power reference value equals a power limit value. In some embodiments, the first condition is fulfilled when the measured value of the rotor speed and the output power reference value have respectively reached the speed limit value and power limit value within certain predetermined periods of time, i.e. recently.

[0034] At 130, it is determined whether a second condition is fulfilled. This is the case when the blade pitch angle reference value fulfills a pitch condition and the activation level of the adaptive flow regulating system fulfills an adaptive flow regulating condition, or when the measured value of the rotor speed is below the speed limit value.

[0035] More specifically, the pitch condition may be fulfilled when [0036] a difference between the reference value for the blade pitch angle and a predetermined minimum pitch angle value is below a first pitch threshold value, or [0037] an estimate for the time it will take before the reference value for the blade pitch angle reaches the predetermined minimum pitch angle is below a second pitch threshold value.
In other words, the pitch condition is fulfilled when the reference value for the blade pitch angle is close to the predetermined minimum pitch angle or soon will be.

[0038] The adaptive flow regulating condition may be fulfilled when [0039] the reference value for the activation level of the adaptive flow regulating system is below a first flow regulating threshold value, or [0040] an estimate for the time it will take before the reference value for the activation level of the adaptive flow regulating system reaches a value corresponding to an inactive adaptive flow regulating system is below a second flow regulating threshold value.
In other words, adaptive flow regulating condition is fulfilled when the adaptive flow regulating system is close to being inactive or soon will be.

[0041] Then, at 140, the full-power flag is set if the first condition is fulfilled and the second condition has not been fulfilled for a certain (first) period of time.

[0042] Furthermore, at 150, the full power flag is cleared if the second condition is fulfilled.

[0043] Thereafter, the method 100 returns to 110 and repeats the steps and actions described above.

[0044] Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

[0045] For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.