Method for operating a wind turbine, wind turbine and computer program product

Abstract

A method for operating a wind turbine, the method including, in response to receiving a request for a system start of the wind turbine, monitoring at least one measured value over a predetermined monitoring period; and effecting the system start in response to determining that the at least one measured value in the monitoring period corresponds to defined specifications, wherein: the at least one measured value is stored continuously in a data storage and a storage period in the data storage corresponds to at least the predetermined monitoring period, and monitoring the at least one measured value in response to receiving the request for the system start comprises checking, on the basis of the data storage, whether the at least one measured value in a storage period corresponding to the monitoring period before the request corresponds to the defined specifications.

Claims

1. A method for operating a wind turbine, the method comprising: in response to receiving a request for a system start of the wind turbine, monitoring at least one measured value over a predetermined monitoring period; and effecting the system start in response to determining that the at least one measured value in the monitoring period corresponds to defined specifications, wherein: the at least one measured value is stored continuously in a data storage and a storage period in the data storage corresponds to at least the predetermined monitoring period, and monitoring the at least one measured value in response to receiving the request for the system start comprises checking, on the basis of the data storage, whether the at least one measured value in a storage period corresponding to the monitoring period before the request corresponds to the defined specifications.

2. The method of claim 1, wherein the data storage is a ring buffer.

3. The method of claim 1, wherein at least two measured values are stored continuously in the data storage and checked upon the request for the system start.

4. The method of claim 3, wherein differing monitoring periods or storage periods are specified for the at least two measured values.

5. The method of claim 3, wherein differing monitoring periods and storage periods are specified for the at least two measured values.

6. The method of claim 1, wherein reference data are stored continuously in the data storage over a storage period, the reference data are configured for checking plausibility of the at least one measured value, and the storage period of the reference data corresponds at least to the monitoring period of the at least one measured value to be checked for plausibility.

7. The method of claim 6, comprising in response to finding a plausibility deficiency, emptying the data storage.

8. The method of claim 6, wherein the plausibility checking is based on at least one of maximum values, minimum values, gradients, mean values, and standard deviations.

9. The method of claim 6, wherein the reference data include at least one of an angle of attack of the rotor blades and a rotor rotational speed.

10. The method of claim 1, wherein the at least one measured value or the reference data that are stored in the data storage are checked for plausibility during the continuous storage or during the checking of the at least one measured value upon the request for a system start.

11. The method claim 1, wherein the at least one measured value comprises a measurement of at least one of wind direction, wind speed, nacelle azimuth position, tower head acceleration, tower vibration signals, temperature of the environment, and temperature of individual components of the wind turbine.

12. The method of claim 1, wherein the monitoring period is at least 60 seconds.

13. The method of claim 1, wherein the at least one measured value and the reference data that are stored in the data storage are checked for plausibility during the continuous storage or during the checking of the at least one measured value upon the request for a system start.

14. The method of claim 1, wherein the monitoring period is at least 120 seconds.

15. A wind turbine comprising: a rotor having a plurality of rotor blades, the rotor being rotatably arranged on a nacelle that is arranged on a tower; a generator arranged in the nacelle for converting wind energy acting on the rotor into electrical energy; at least one sensor for sensing at least one measured value; a data storage for continuously storing the sensed at least one measured value for a storage period; and a closed-loop control system for controlling the wind turbine, wherein the control system is configured for verifying, in response to a request for a system start, on the basis of the data storage, whether the at least one measured value in the period corresponding to a predetermined monitoring period corresponds to predefined specifications before the request, wherein the storage period corresponds to at least the predetermined monitoring period, and the closed-loop control system is configured to start the wind turbine verifying that the at least one measured value corresponds to the predefined specifications.

16. The wind turbine of claim 15, wherein the data storage is a ring buffer.

17. A non-transitory computer readable medium comprising instructions that, when executed by a computer processor of a wind turbine, cause the wind turbine to: in response to receiving a request for a system start of the wind turbine, monitor at least one measured value over a predetermined monitoring period; and effect the system start in response to determining that the at least one measured value in the monitoring period corresponds to defined specifications, wherein: the at least one measured value is stored continuously in a data storage and a storage period in the data storage corresponds to at least the predetermined monitoring period, and monitoring the at least one measured value in response to receiving the request for the system start comprises checking, on the basis of the data storage, whether the at least one measured value in a storage period corresponding to the monitoring period before the request corresponds to the defined specifications.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be described by way of example with reference to the accompanying drawings, on the basis of a preferred embodiment. There are shown:

(2) FIG. 1 shows a first exemplary embodiment of a wind turbine according to the invention; and

(3) FIG. 2 shows a schematic representation of the verification module and of the data storage of the wind turbine from FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

(4) Shown schematically in FIG. 1 is a wind turbine 1 according to the invention. The wind turbine 1 comprises a rotor 2, which has a plurality of rotor blades 3 that can be adjusted in the angle of attack, and which is rotatably arranged on a nacelle 4. The nacelle 4 in turn is rotatably arranged on a tower 5.

(5) Via the rotor shaft, the rotor 2 drives a transmission 6 that, on its output side, is connected to a generator 7. A wind-induced rotational motion of the rotor 2 can thus be converted into electrical energy, which then, possibly via inverters (not represented) and/or transformers 8, can be fed into an electricity grid.

(6) The wind turbine 1 additionally comprises a closed-loop control system 10, which is connected via control lines, not represented, to the various components of the wind turbine 1 for the purpose of controlling them. The closed-loop control system 10 is designed, inter alia, to align the rotor 2 according to the wind, by rotating the nacelle 4 relative to the tower 5. The angle of attack of the rotor blades 3 and the electrical power fed into the grid 9 are also controlled by the closed-loop control system 10. By altering the angle of attack of the rotor blades 3 and the electrical power fed into the grid 9, the closed-loop control system 10 can influence the rotor moment, or generator moment.

(7) The closed-loop control system 10 is connected to various sensors 11, to enable the required control task to be performed. One of these sensors 11 is the wind sensor 11, by means of which the wind direction and the wind speed can be determined. Additionally connected to the closed-loop control system is an acceleration sensor 11, by which the tower head acceleration can be sensed. A further acceleration sensor 11 is also provided, at approximately half the height of the tower 5, by which vibration modes of the tower 5, that cannot be sensed by the acceleration sensor 11 alone, can be sensed. Information concerning the state of the electricity grid 9 can be sensed by means of the voltage sensor 11.sup.IV. The sensor 11.sup.V senses the rotational speed of the rotor 2.

(8) In addition, yet further (not represented) sensors 11 may be provided for the nacelle azimuth positioni.e. the angular position of the nacelle 4 relative to the tower 5or for the angle of attack of the rotor blades 3. The sensors 11 are usually already provided for the general control of the wind turbine 1 by the closed-loop control system 10.

(9) Provided according to the invention, as part of the closed-loop control system 10, is a verification module 12, which is connected to a data storage 13. The closed-loop control system 10, or the verification module 12, is designed in such a manner that data sensed by at least one of the sensors 11 is stored continuously for a storage period in a data storage 13 realized as a ring buffer 13.

(10) If the wind turbine 1 is not feeding any electrical power, generated from the kinetic energy of the wind, into the grid, for example because of a fault in the grid 9 or in the wind turbine 1 itself, following elimination of the corresponding fault the closed-loop control system 10 receives a request to restart. For this case, the verification module 12 is designed so as to check, on the basis of the data stored in the ring storage 13, whether a system start is possible.

(11) The functioning of the verification module 12 and the ring storage 13 are explained in greater detail on the basis of FIG. 2.

(12) The ring storage 13 is constructed in the form of a plurality of ring buffers and is supplied, for example via the closed-loop control system 10 or via the verification module 12, with the data from the sensors 11 for the wind speed (sensor 11), the rotor rotational speed (sensor 11.sup.V), the tower head acceleration (sensor 11), the acceleration at half-height of the tower 5 (sensor 11) and the rotor rotational speed (sensor 11.sup.V).

(13) These sensor data are stored continuouslyi.e. irrespective of whether the wind turbine is or is not feeding electrical power, generated from the kinetic energy of the wind, into the gridin separate ring buffers 14 in the ring storage 13. The data relating to wind speed and rotor rotational speed are stored in the ring buffers 14 and 14.sup.V, which each have a storage period of 120 seconds; the tower acceleration data from the sensors 11 and 11 are stored in the ring buffers 14 and 14 having a storage period of 20 seconds.

(14) The sectors of the ring buffers 14 represented in FIG. 2 in this case merely illustrate the length of the storage period of the individual ring buffers 14, in seconds, but not the time resolution in which the data from the sensors 11 are present. In particular, the data from the sensors 11 and 11 relating to the tower acceleration data are present in a high resolution, of several measured values per second. It is also possible for the high-resolution tower acceleration data to be preprocessed in a sensor data processing system (not represented), and for only status signals for the tower acceleration to be stored, in a lower resolution relative to the high-resolution tower acceleration data, in the ring storage 13.

(15) Received data are in each case written to the location of the pointers 15, 15 revolving in the direction 90, such that, following a complete revolution of a pointer 15, 15, the data stored at a location are overwritten by new data. The revolution speeds of the pointers 15, 15 differ. Thus, for one revolution, the pointer 15 requires 120 seconds, the pointer 15 requiring only 20 seconds.

(16) The data concerning the wind speed and the tower accelerations stored in the ring buffers 14, 14 and 14 are measured values within the meaning of the present invention, whereas the data stored in the ring buffer 14.sup.V are reference data thatas explained in the followingare used merely to check the plausibility of the other data, but not to check directly whether a system start is allowed.

(17) If the closed-loop control system 10 of the wind turbine 1, which is not feeding any electrical power, generated from the kinetic energy of the wind, into the grid, receives a request to restart, the verification unit first checks the plausibility of the data currently contained in the ring buffers 14 and 14.sup.V. For this purpose, it is checked whether the wind speeds (ring buffer 14) basically correlate in respect of time with the rotor rotational speed (ring buffer 14.sup.V)which, in the case of a wind turbine not feeding any electrical energy, generated from the kinetic energy of the wind, into the grid, is the coasting rotational speedover the entire storage period. If this is not the case, this may be an indication that at least one of the sensors 11 or 11.sup.V is defective. In this case, a system start is prevented by the verification module 12, and a warningfor example via a SCADA system (Supervisory Control and Data Acquisition System), not representedmay be emitted.

(18) If the plausibility check is concluded successfully, the verification module 12 then checks whether the measured values stored in the ring buffers 14, 14 and 14 fulfill the specifications 16 in the verification module 12.

(19) Additionally or alternatively, the plausibility check may also be effected continuously, i.e. already during storage of the data. Defective sensors 11 can thus be identified more rapidly. Only the case of a corrupt data storage 13 can then not be identified until the data is read out.

(20) For the ring buffer 14, it is checked whether the measured values stored therein are within a range, defined by a minimum and a maximum value, over the entire storage period. Since the measured values are checked over the entire storage period, the monitoring period for the wind speed corresponds to the storage period, i.e. 120 seconds in the exemplary embodiment represented.

(21) The measured values relating to the tower accelerations stored in the ring buffers 14 and 14 are supplied over the entire storage period, which therefore corresponds to the monitoring period for the tower accelerations, to an analysis module 17 in the verification module 12, where the energy into the individual eigenforms of the tower 5 is determined from the measured values. In this case, there is a specification 16 for the maximum vibration energy for each eigenform.

(22) If all measurement values in the ring buffers 14, 14 and 14 over the respective monitoring period correspond to the defined specifications 16, the check performed by the verification module 12 produces a positive result, whereupon the closed-loop control system 10 starts the wind turbine 1 in accordance with a predefined process. If the check is negative, the wind turbine 1 is initially not started, and the prescribed checking of the measured values is performed until the check has been concluded successfully. If the result of the test is negative, a corresponding indicatione.g. via a SCADA system, not representedmay be emitted.

(23) If the plausibility check described above is not concluded successfully, all data in the ring buffers 14 and 14.sup.V are erased, or zeroed, by the verification module and, at the same time, the sensors 11 and 11.sup.V are reinitialized. Subsequently, the previously described checking of the measured values from the ring buffer 14 will remain unsuccessful, at least until at least the ring buffer 14 is again completely full with measured values obtained after the reinitialization of the sensors 11 and 11.sup.V.