System for automatic power estimation adjustment

Abstract

An automatic adjustment system for a variable-speed wind turbine is provided, having a power vector generator for generating a power vector (P.sub.vec) of wind turbine output power; a mapping unit for establishing relationships (β.sub.vec, ω.sub.vec) between wind turbine output power and rotational speed and pitch angle on the basis of the power vector (P.sub.vec) and an operational trajectory of the wind turbine; a wind speed estimator for estimating a wind speed (v.sub.est); an available power calculator for calculating the available power (P.sub.est) of the wind turbine on the basis of the estimated wind speed (v.sub.est) and the established relationships (β.sub.vec, ω.sub.vec). A method of performing automatic analysis of a wind turbine configuration, a computer program product for carrying out the steps of such a method, and a wind turbine having such an automatic adjustment system are also provided.

Claims

1. An automatic adjustment system for a variable-speed wind turbine, which automatic adjustment system comprises a controller including: a power vector generator for generating a power vector of wind turbine output power; a mapping unit for establishing relationships between wind turbine output power and rotational speed and pitch angle on the basis of the power vector and an operational trajectory of the wind turbine; a wind speed estimator for estimating a current wind speed based on measured values of produced active power, the rotational speed and the pitch angle; and an available power calculator for adjusting an estimate of available power of the wind turbine on the basis of the estimated wind speed and the established relationships; wherein the controller to regulate the wind turbine in response to the estimated available power including control of the pitch angle of rotary blades of the wind turbine.

2. The automatic adjustment system according to claim 1, further comprising a memory module for storing a Cp matrix, wherein the Cp matrix defines a relationship between a rotational velocity of a wind turbine rotor, the pitch angle of the rotor blades, a power value and a wind speed value.

3. The automatic adjustment system according to claim 1, further comprising a memory module for storing a power curve for that wind turbine, wherein the power curve defines a relationship between wind speed and maximum power output for the wind turbine.

4. The automatic adjustment system according to claim 1, further comprising a memory module for storing a pitch curve and a speed/power curve for the wind turbine, wherein the pitch curve defines the relationship between the pitch angle and the output power for the wind turbine, and the speed/power curve defines the relationship between the rotational speed and the output power for the wind turbine.

5. The automatic adjustment system according to claim 1, further comprising a power value input for providing a current power value for the wind turbine.

6. The automatic adjustment system according to claim 1, further comprising a rotational velocity input for providing a current rotational velocity value for the wind turbine.

7. A wind turbine comprising an automatic adjustment system according to claim 1.

8. A method, comprising: generating, by a controller, a power vector of wind turbine output power; establishing, by the controller, relationships between wind turbine output power and rotational speed and pitch angle on the basis of the power vector and an operational trajectory of the wind turbine; estimating, by the controller, a wind speed based on measured values of produced active power, the rotational speed and the pitch angle; adjusting, by the controller, an estimate of available power of the wind turbine on the basis of the estimated wind speed and the established relationships; and regulating, by the controller, the wind turbine in response to the estimated available power including control of the pitch angle of rotary blades of the wind turbine.

9. The method according to claim 8, wherein the step of generating the power vector is automatically performed in the event of an alteration in the operational trajectory of the wind turbine.

10. The method according to claim 8, wherein the power vector is computed with a fixed step size.

11. The method according to claim 8, wherein the estimated available power is adjusted at predefined regular intervals.

12. The method according to claim 8, wherein the estimated available power is adjusted in response to an alteration in the estimated wind speed.

13. The method according to claim 8, wherein the power vector comprises a step size interval of at most 100 kW.

14. The method according to claim 8, wherein the power vector extends beyond a value of rated power of the wind turbine.

15. A computer readable memory having a computer program product stored thereon which when executed causes a processor to: generate a power vector of wind turbine output power; establish relationships between wind turbine output power and rotational speed and pitch angle on the basis of the power vector and an operational trajectory of a wind turbine; estimate a wind speed based on measured values of produced active power, the rotational speed and the pitch angle; adjust an estimate of available power of the wind turbine on the basis of the estimated wind speed and the established relationships; and regulate the wind turbine in response to the estimated available power including control of the pitch angle of rotary blades of the wind turbine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a block diagram of an automatic adjustment system according to an embodiment of the invention;

(2) FIG. 2 shows a speed/power curve for a wind turbine;

(3) FIG. 3 shows a pitch curve for a wind turbine;

(4) FIG. 4 shows an rpm/pitch data set for a wind turbine;

(5) FIG. 5 shows a power curve for a wind turbine;

(6) In the diagrams, like numbers refer to like objects throughout. Objects in the diagrams are not necessarily drawn to scale.

DETAILED DESCRIPTION OF INVENTION

(7) FIG. 1 shows a block diagram of an automatic adjustment system 1, for the automatic estimation of available power, according to an embodiment of the invention. This is shown as part of a wind turbine 2, for example the automatic adjustment system 1 can be realised as one or more modules of a computer program to be run on a processor or computer of the wind turbine 2. In this exemplary embodiment, the automatic adjustment system 1 comprises various memory modules M for storing data relating to the wind turbine 2. Here, the memory modules M store one or more speed/power curves, pitch curves, rpm/pitch data sets, and power curves.

(8) The automatic adjustment system 1 comprises a power vector generator 10 for generating a power vector P.sub.vec of the wind turbine 2. The power vector P.sub.vec is forwarded to a mapping block 11 or look-up block 11 realised to interpret one or more speed/power curves 130 and pitch curves 131 to determine a pitch vector β.sub.vec comprising a set of values corresponding to the points of the power vector P.sub.vec, i.e. the pitch vector β.sub.vec comprises a set of points, whereby each point is a matching value of pitch for each point in the power vector P.sub.vec. Similarly, the mapping block 11 outputs a rotational speed vector ω.sub.vec for that power vector P.sub.vec. The pitch and rotational speed vectors β.sub.vec, ω.sub.vec in turn are used by power curve compilation unit 12 that compiles a power curve 133 relating maximum output power to various wind speed values, for example points in a wind speed vector. The wind speed vector and the power vector P.sub.vec together define the power curve 133 for that wind turbine 2.

(9) The automatic adjustment system 1 comprises a wind speed estimator 13 which estimates the wind speed v.sub.est on the basis of a power matrix 132 for that wind turbine 2. The estimated wind speed v.sub.est is forwarded to an available power look-up table 14 realised to determine the available power P.sub.est of the wind turbine 2 on the basis of the estimated wind speed v.sub.est.

(10) The automatic adjustment system 1 can be provided with up-to-date operational values P.sub.c, β.sub.c, ω.sub.c of the wind turbine 2, such as the power P.sub.c that is currently being output by the wind turbine 2, the blade pitch angle β.sub.c, the rotational velocity ω.sub.c of the rotor, etc. Such information can be provided by a main computer 20, which generally records all relevant operating parameters of the wind turbine 2. Equally, a sensor such as a rotational speed sensor 21 might be used to provide values of current rotational velocity ω.sub.c of the rotor. Of course, even though the main computer 20 is shown here as a separate block, the automatic adjustment system 1 could itself be realised as a computer program product to run on the main computer 20 of the turbine, or on a computer of a wind park controller, etc.

(11) The estimated available power value P.sub.est can be forwarded to a suitable target, for example an operator or a wind park controller, which can record the information or evaluate it. The estimated available power value P.sub.est can be used to calculate the revenue for that wind turbine 2, and/or can be used to regulate the operation of the wind turbine 2 in a more efficient manner.

(12) FIG. 2 shows a speed/power curve 130 for a wind turbine. This shows the configured relationship between rotational velocity ω [rpm] of the wind turbine's rotor and the power P [kW]. This information establishes the relationship between power and rotational speed in used by block 11 of the automatic adjustment system 1 of FIG. 1.

(13) FIG. 3 shows a pitch curve 131 for a wind turbine. This shows the configured relationship between power P [kW] and pitch angle β [°]. This information is used by the automatic adjustment system 1 of FIG. 1.

(14) Taken in combination, the information presented in FIGS. 2 and 3 is the “configured operational trajectory” of the wind turbine. Values of rotational velocity and pitch angle are effectively tied to values of output power of the wind turbine. The rotational speed of the blades may be altered, for example, as a result of a change in wind speed and/or because of a need to comply with noise regulations. The blade pitch angle may be altered, for example in order to increase or decrease rotor torque and/or because of a need to comply with noise regulations.

(15) FIG. 4 shows the power matrix or “Cp matrix” as rpm, pitch, wind speed data sets 132 for a wind turbine. For each value of wind speed (exemplary values are shown in the upper right corner of each “data set” 132), the influence of pitch angle β [°] and rotor rotational velocity w [rpm] on the current value of output power is shown as a set of Cp curves. Each “contour line” represents a certain output power value. For example, for the Cp curves at the front of the stack, the output power at a wind speed of 7 m/s is plotted for all reasonable combinations of pitch angle β and rotor rotational velocity. The information presented by the Cp curves for a wind turbine can have been previously collected in a calibration step or calculated based on models.

(16) The wind speed estimator 13 of FIG. 1 applies the information it has received i.e. measured values of power P.sub.c, pitch angle β.sub.c and the rotational speed ω.sub.c to determine an accurate estimation of the momentary wind speed v.sub.est. For example, the wind speed estimator 13 may have identified the Cp curve shown at the front of the stack, and may have concluded that the current wind speed must be 7 m/s. This estimated wind speed v.sub.est can then be used by the available power look-up table 14 to obtain an estimation of the available output power P.sub.est.

(17) Of course, rpm/pitch data sets could be compiled or collected during normal operation of the wind turbine, and the method according to the invention can be implemented once sufficient quantities of data have been collected for output power, rotational velocity, pitch and wind speed values.

(18) FIG. 5 shows a power curve for a wind turbine. This shows the relationship between wind speed v [ms.sup.−1] and available power P.sub.av [kW]. For example, with a reliable estimate of the current wind speed v.sub.est, it is possible to determine, with a corresponding high level of accuracy, an accurate estimate of the available power P.sub.est that the wind turbine is capable of producing under the current conditions. With this information, it is possible to more accurately compute the available power for that wind turbine.

(19) As already mentioned in the above, the “curves” and data sets are stored in a digital manner in a memory module, and are only shown as plotted curves in the above for the sake of illustration. The skilled person will appreciate that such “curves” are generally stored as value pairs, and that points between adjacent value pairs can be determined by applying a suitable interpolation algorithm. Similarly, the method according to the invention can automatically interpolate between adjacent Cp curves in a stack, if it concludes that the current wind speed lies between the wind speeds of two candidate Cp curves.

(20) 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.

(21) 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. The mention of a “unit” or a “module” does not preclude the use of more than one unit or module.