METHOD FOR OPERATING A WIND POWER PLANT

Abstract

The invention relates to a method for operating a wind power plant, a wind power plant designed to carry out the method, and a corresponding computer program product. In the method for operating a wind power plant comprising a rotor having angle-adjustable rotor blades and a generator rotationally connected thereto and having a controllable torque, the torque of the generator is limited to a maximum value which is linked to the blade pitch angle of the rotor blades such that the maximum value at the switch-on blade pitch angle value is less than or equal to the rated torque value (M.sub.Nenn) and the maximum value at a rated blade pitch angle which deviates from the switch-on blade pitch angle is equal to the rated torque value (M.sub.Nenn).

Claims

1. A method for operating a wind power plant comprising a rotor with angle-adjustable rotor blades and a generator rotationally connected thereto and having a controllable torque, wherein the torque of the generator is limited to a maximum value that is linked to the blade pitch angle of the rotor blades in such a way that the maximum value at the switch-on blade pitch angle is less than or equal to the rated torque value (M.sub.Nenn) and the maximum value at a rated blade pitch angle that differs from the switch-on blade pitch angle is equal to the rated torque value (M.sub.Nenn).

2. The method of claim 1, wherein the blade pitch angle on reaching the maximum value of the torque is changed.

3. The method of claim 1, wherein the link between the maximum value for the torque and the blade pitch angle is made on the basis of a preferably parameterized characteristic curve.

4. The method of claim 3, wherein the characteristic curve and/or the rated blade pitch angle is changed depending on the operating mode of the wind power plant and/or on the ambient conditions.

5. The method of claim 3, wherein the change to the characteristic curve takes the loading dynamic (qDyn) of the wind power plant into consideration.

6. The method of claim 1, wherein the blade pitch angle of the rotor blades and the torque of the generator are regulated toward a blade pitch angle setpoint value (αSoll) and a torque setpoint value (MSoll), wherein the maximum value (MSoll;Max) is limited to the torque setpoint value (MSoll), and is linked to the blade pitch angle setpoint value (αSoll).

7. A wind power plant comprising a rotor with a plurality of rotor blades whose blade pitch angle is adjustable that is arranged rotatably at a nacelle that is arranged rotatably on a tower and is connected via a drivetrain to a generator arranged in the nacelle for the conversion of wind energy acting on the rotor into electrical energy, and a plant controller for controlling the wind power plant and its components, wherein the plant controller is designed to carry out the method of claim 1.

8. The wind power plant of claim 7, wherein the plant controller is designed, on reaching the maximum value of the torque (MSoll;Max), to control the blade pitch angle of the rotor blades depending on the rotation speed of the rotor.

9. The wind power plant of claim 8, wherein the plant controller is designed to increase or reduce the torque and/or the torque setpoint value (MSoll) for a period of time in order to influence the rotation speed of the rotor.

10. A computer program product comprising program segments which, if loaded into a computer, preferably the plant controller of a wind power plant, are designed to carry out the method of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The invention will now be described by way of example on the basis of one preferred embodiment, having reference to the appended drawings, in which:

[0028] FIG. 1 shows a schematic illustration of the nacelle of a wind power plant as claimed in the invention designed to carry out the method as claimed in the invention; and

[0029] FIG. 2 shows the schematic sketch of one possible performance of the method as claimed in the invention; and

[0030] FIG. 3 shows a possible characteristic curve for linking the blade pitch angle to the maximum value for the torque.

DETAILED DESCRIPTION

[0031] The nacelle 2 of a wind power plant 1 as claimed in the invention, and therefore designed for carrying out the method as claimed in the invention, is shown schematically in FIG. 1. The wind power plant 1 comprises a rotor 3 with a total of three rotor blades 5 fastened rotatably by way of blade pitch angle adjustment devices (not shown) to a rotor hub 4. The rotor 3 is arranged rotatably at the nacelle 2 which is in turn arranged by way of an azimuth drive 14 rotatably about a vertical axis on a tower 6.

[0032] The rotor hub 4 is joined via a rotor shaft 7 via an intermediate gearbox 8 to a generator 9 for converting wind energy acting on the rotor 3 into electrical energy. The components that transmit power from the rotor 3 to the generator 9—that is in particular the rotor shaft 7 and the gearbox 8—form the drivetrain 10.

[0033] In the exemplary embodiment illustrated, the generator 9 is a double-fed asynchronous generator in which a part of the generated power is fed directly, and another part of the power via a converter 11 and a switching element 12, to a transformer (not shown) located at the foot of the tower 6 and from there fed into a public supply grid.

[0034] Between the gearbox 7 and the generator 9 a brake 13 is furthermore provided with which a rotary movement of the drive train 10 can be braked and, if necessary, the rotor 3 stopped. In addition, measuring transducers 14 are provided for ascertaining the rotation speed of the rotor or the rotation speed of the shaft 7 between the gearbox 8 and the generator 9.

[0035] The wind power plant 1 and all of its components are controlled by the computer-based plant controller 20. For this purpose, all of the measured values acquired in the wind power plant 1 are supplied to the plant controller 20, as well as, via a data line 21, target values, for example from a network operator, and, with the aid of control algorithms stored in a memory 22 and in principle known to the expert, converted into control signals which in turn are output to the various components of the wind power plant 1. In a first part, the plant controller 20 ascertains, on the basis of the information that is present, target values for individual parameters of operating the wind power plant 1 that it can control, which are then converted by other parts of the plant controller 20 in such a way that the corresponding actual values correspond to the target values.

[0036] As claimed in the invention, the plant controller 20 is designed for carrying out the method as claimed in the invention described below in more detail, for which purpose a computer program product designed for this is stored in the memory 22 and is carried out by the plant controller 20.

[0037] A schematic sketch for implementing the method as claimed in the invention in the plant controller 20 is shown in FIG. 2. The illustration is limited here to the part of the plant controller 20 that is significant for carrying out the method.

[0038] As already explained, setpoint values for the individual operating parameters of the wind power plant 1 are ascertained by the plant controller 20 on the basis of the captured measured values and other control specifications. These also include setpoint values for the blade pitch angle α.sub.Soll and for the generator torque M.sub.Soll that are converted by further parts of the plant controller 20, not shown in more detail in FIG. 2, into control commands for the individual components of the wind power plant 1, so that the actual blade pitch angle a and the actual generator torque M correspond to the setpoint values. The plant controller 20 also asc0ertains, in accordance with DE 10 2017 011 318.1, a normalized loading dynamic q.sub.Dyn that adopts values between 0 and 1, and provides information about the turbulences occurring at the wind power plant. Not least, the plant controller 20, and thereby also the wind power plant 1, has different operating modes, for example a normal mode and a safe mode in which the power generation is reduced so that even in the event of malfunctions of the wind power plant 1 it does not have to be completely switched off. The operating mode of the plant controller 20 active at any time is reflected in the value of input signal a.sub.Modus.

[0039] The setpoint value for the torque M.sub.Soll, which is ascertained in a known manner, is supplied to a setpoint limiter 23 that limits the setpoint M.sub.Soll to a value between 0 and a maximum value for the torque M.sub.Soll;Max.

[0040] The maximum value M.sub.Soll;Max is ascertained by the calculation module 24, which receives the blade pitch angle setpoint α.sub.Soll, the setpoint for the torque M.sub.Soll, the loading dynamic q.sub.Dyn and the signal a.sub.Modus for the current operating mode as input values.

[0041] For the ascertainment of the maximum value M.sub.Soll;Max, the calculation module 24 refers to a characteristic curve 30, as illustrated by way of example in FIG. 3. The characteristic curve 30 here represents a direct link between the blade pitch angle or the blade pitch angle setpoint value α.sub.Soll and the maximum value for the torque, or its setpoint value M.sub.Soll;Max. A plurality of different characteristic curves are here stored in the calculation module 24, and are selected and used according to the current operating mode depending on the input signal a.sub.Modus. A part of these characteristic curves is, furthermore, parameterized, wherein at least one parameter is changed depending on the loading dynamic q.sub.Dyn.

[0042] The characteristic curve 30 in FIG. 3 is configured for the normal operating mode of the wind power plant 1, and can be changed depending on the loading dynamic q.sub.Dyn.

[0043] For the switch-on blade pitch angle that the rotor blades 5 of the wind power plant 1 have so that the rotor is set into rotation from stationary in the presence of sufficient wind (usually 0°), a maximum value for the torque M.sub.Soll;Max below the rated torque M.sub.Nenn is specified. A blade pitch angle is also specified above which the maximum value for the torque M.sub.Soll;Max corresponds in a constant manner to the rated torque M.sub.Nenn. In the region between the switch-on blade pitch angle and the rated blade pitch angle, above which the maximum value M.sub.Soll;Max is specified as the rated torque M.sub.Nenn, there is a linear relationship between the blade pitch angle setpoint α.sub.Soll and the maximum value for the torque M.sub.Soll;Max. Further characteristic curves can also be specified for other reasons, for example to observe characteristic noise values.

[0044] The rated blade pitch angle changes depending on the load dynamic Q.sub.Dyn. When the load dynamic q.sub.Dyn is low, the rated blade pitch angle in question is shifted in the direction of the switch-on blade pitch angle, but in the opposite direction at a high load dynamic q.sub.Dyn. This is indicated in FIG. 3 by the dashed characteristic curve profiles.

[0045] In addition to the characteristic curve 30 illustrated in FIG. 3 for normal operation, a further characteristic curve for safe minimum operation is stored in the calculation module 24. In this characteristic curve 30, the maximum value for the torque M.sub.Soll;Max is specified as having a constant value for all blade pitch angles.

[0046] The calculation module 24 calculates, on the basis of the characteristic curve applicable for the operating mode at the time, the maximum value for the torque M.sub.Soll;Max, and provides this to the setpoint limiter 23 as an input value for limiting the setpoint value M.sub.Soll, from which the setpoint value M′.sub.Soll, which may be limited to the maximum value M.sub.Soll;Max, results. This setpoint value M′.sub.Soll can now in principle be used for the final control of the generator torque.

[0047] In the exemplary embodiment illustrated in FIG. 2, the calculation module 24 is furthermore designed in certain operating modes reflected in the value of input signal a.sub.Modus and/or above a certain loading dynamic q.sub.Dyn, to have an influence on the rotation speed of the rotor 3 of the wind power plant 1 by temporarily increasing and reducing the setpoint value M′.sub.Soll ascertained by the setpoint limiter 23 to the setpoint M″.sub.Soll, which, with appropriate configuration of the plant controller 20 results in the known manner in a change to the blade pitch angle of the rotor blades 5.