An early warning and protection method for the oscillation of the pitch system of a wind turbine

Abstract

The present invention relates to the technical field of wind power generation, and discloses a warning and protection method for the oscillation of the pitch system of a wind turbine. By monitoring and analyzing the operation data values of the pitch system of the wind turbine, it is determined whether there is oscillation in the pitch system. If the determination result is yes, a fault alarm is given to the wind turbine and it is shut down; if the determination result is no, the normal operation of the wind turbine is maintained. The present invention solves the problems existing in the prior art that the actions of the pitch system itself cannot be monitored and warned, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation, and specifically to a warning and protection method for the oscillation of the pitch system of a wind turbine generator set. Background Art

[0002] With the gradual realization of grid parity for wind turbine generator sets, wind power manufacturers have popularized units with long blades and high towers in order to reduce manufacturing costs, resulting in a decrease in the stiffness and an increase in the flexibility of the units. The tiny movements of the pitch system have a more and more obvious impact on the vibration, load and fatigue life of large components of the unit. This requires the pitch system to reduce unnecessary pitch changes to avoid pitch system oscillation, and at the same time, it is necessary to monitor the pitch system oscillation caused by external factors. The existing solutions are to detect the change trend of wind speed or power, and only give the pitch angle position command when it exceeds the threshold, otherwise the pitch angle position command remains unchanged from the previous value. This method only reduces the pitch action times from the smoothness of the command, and cannot monitor and warn the actions of the pitch system itself. If there are periodic fluctuations in the pitch angle position command itself or alternating loads exist externally, the system oscillation will still be caused. Summary of the Invention

[0003] To overcome the deficiencies of the prior art, the present invention provides a warning and protection method for the oscillation of the pitch system of a wind turbine generator set, which solves the problems existing in the prior art such as the inability to monitor and warn the actions of the pitch system itself.

[0004] The technical solution adopted by the present invention to solve the above problems is:

[0005] A warning and protection method for the oscillation of the pitch system of a wind turbine generator set, by monitoring and analyzing the operation data values of the pitch system of the wind turbine generator set, to judge whether there is oscillation in the pitch system. If the judgment result is yes, then give a wind turbine fault alarm and stop the machine; if the judgment result is no, then keep the wind turbine running normally.

[0006] As a preferred technical solution, it includes the following steps:

[0007] S1, collect the operation data values of K categories of three axes of the pitch system of the wind turbine generator set;

[0008] S2, perform power spectral density analysis on the operation data values to obtain 3K groups of frequencies and their corresponding powers;

[0009] S3, select the maximum value of the power in each group;

[0010] S4, select the frequency corresponding to the maximum power value, and calculate the average value of the powers corresponding to the frequencies within the range with this frequency as the center and the data length of N;

[0011] S5. Calculate the absolute value of the difference between the maximum power corresponding to each frequency and the average power of that frequency, and compare the absolute value of the difference with the set threshold value.

[0012] S6. If the absolute value of the difference > the set threshold value, then give a wind turbine fault alarm and stop the machine; otherwise, the wind turbine operates normally.

[0013] As a preferred technical solution, in step S1, K = 3, and the operation data values are the actual pitch angle, pitch rate, and motor current respectively.

[0014] As a preferred technical solution, in step S4, 3 ≤ N ≤ 10.

[0015] As a preferred technical solution, in step S4, N = 10.

[0016] As a preferred technical solution, in step S6, when giving a wind turbine fault alarm, display the category of the shaft of the pitch system where the fault occurs.

[0017] As a preferred technical solution, in step S6, when exceeding the threshold value, give a stop command to control the pitch of the unit.

[0018] As a preferred technical solution, in step S5, the set threshold value is 5 - 15 dB.

[0019] As a preferred technical solution, in step S1, it is set to collect the operation data values of the pitch system of the wind turbine every t ms, where 1 ≤ t ≤ 20.

[0020] As a preferred technical solution, in step S1, the length of the collected data is T minutes, where 1 ≤ T ≤ 10.

[0021] The present invention has the following beneficial effects compared with the prior art:

[0022] By monitoring the position, speed, and current (or torque value) of the pitch system of the wind turbine, the present invention can effectively determine whether there is oscillation in the pitch system, report a fault, and execute a shutdown procedure for protection, which can effectively protect against frequent pitching caused by abnormal pitch position commands or external load alternation (such as vortex-induced vibration), and avoid further danger to the unit. Description of the Drawings

[0023] Figure 1 It is a schematic flow diagram of Embodiment 2 of the present invention;

[0024] Figure 2 It is a schematic diagram of the comparison method of the maximum value and the average value of Embodiment 2 of the present invention. Detailed Embodiments

[0025] The present invention will be further described in detail below in conjunction with embodiments and the accompanying drawings. However, the embodiments of the present invention are not limited thereto.

[0026] Embodiment 1

[0027] As Figure 1 , Figure 2 shown, a warning and protection method for the oscillation of the pitch system of a wind turbine determines whether there is oscillation in the pitch system by monitoring and analyzing the operation data values of the pitch system of the wind turbine. If the judgment result is yes, a fault alarm for the wind turbine is given and the machine is stopped; if the judgment result is no, the normal operation of the wind turbine is maintained.

[0028] By monitoring and analyzing the operation data values of the pitch system of the wind turbine, it is possible to effectively determine whether there is oscillation in the pitch system, report a fault and execute a shutdown procedure for protection, which can effectively protect against frequent pitching caused by abnormal pitch position commands or external load alternations (such as vortex-induced vibration), and avoid further risks to the unit.

[0029] As a preferred technical solution, it includes the following steps:

[0030] S1. Collect the operation data values of K categories of three axes of the pitch system of the wind turbine;

[0031] S2. Perform power spectral density analysis on the operation data values to obtain 3K groups of frequencies and their corresponding powers;

[0032] S3. Select the maximum value of the power in each group;

[0033] S4. Select the frequency corresponding to the maximum power of the power, and calculate the average value of the powers corresponding to the frequencies within the range centered on this frequency and with a data length of N;

[0034] S5. Calculate the absolute value of the difference between the maximum power value corresponding to each frequency and the average power value of this frequency, and compare the size of the absolute value of the difference with the set threshold;

[0035] S6. If the absolute value of the difference > the set threshold, a fault alarm for the wind turbine is given and the machine is stopped; otherwise, the wind turbine operates normally.

[0036] The above steps further refine the warning and protection method for the oscillation of the pitch system of the wind turbine.

[0037] As a preferred technical solution, in step S1, K = 3, and the operation data values are the actual pitch angle, pitch rate, and motor current respectively.

[0038] The actual pitch angle, pitch rate, and motor current data have the advantages of being easy to collect and high recognition accuracy.

[0039] As a preferred technical solution, in step S4, 3 ≤ N ≤ 10.

[0040] As a preferred technical solution, in step S4, N = 10.

[0041] It should be noted that after power spectral density analysis, a spectrum with frequency as the horizontal axis and power as the vertical axis is obtained. Taking the frequency corresponding to the maximum power as the center and selecting the power corresponding to the frequencies within the range of the verified data length N as the calculation interval, the average power can be calculated more accurately and quickly. The calculation interval should not be too wide, as this will increase the calculation amount; nor should it be too narrow, as this will result in lower accuracy. Through experiments, 3 ≤ N ≤ 10, especially N = 10, can achieve better calculation results. The above value of N further ensures the effectiveness of calculating the average power.

[0042] As a preferred technical solution, in step S6, when a wind turbine fault alarm is issued, the category of the axis of the pitch system where the fault occurs is displayed.

[0043] This facilitates further determination of which axis of the pitch system the fault occurred in.

[0044] As a preferred technical solution, in step S6, when the threshold is exceeded, a shutdown command is given to control the pitch of the unit.

[0045] This facilitates early warning and protection through the pitch angle position command.

[0046] As a preferred technical solution, in step S5, the threshold is set to 5 - 15 dB.

[0047] As a preferred technical solution, in step S1, it is set to collect the operating data values of the wind turbine pitch system every t ms, where 1 ≤ t ≤ 20.

[0048] As a preferred technical solution, in step S1, the data length collected is T minutes, where 1 ≤ T ≤ 10.

[0049] The above settings of the threshold, t, and T take into account efficiency while ensuring accuracy.

[0050] Embodiment 2

[0051] As Figure 1 、 Figure 2 shown, as a further optimization of Embodiment 1, on the basis of Embodiment 1, this embodiment further includes the following technical features:

[0052] 1. The main controller of the wind turbine collects the actual pitch angles, pitch rates, and motor currents of the three axes of the pitch system within time T, and stores them in the array variables Pos1, Pos2, Pos3, Spd1, Spd2, Spd3, Curr1, Curr2, and Curr3 respectively;

[0053] 2. Perform power spectral density analysis on these variables using the Pwelch function respectively. Among them, the calculated power values need to be processed by 10*log10 logarithm, and the results are stored in the array variables f1 - f9 and P1 - P9 respectively;

[0054] 3. Use the findpeaks function to find the maximum values (stored in the array variables Peak1 - Peak9) and the corresponding serial numbers in the array variables P1 - P9, and find the corresponding frequency values in the array variables f1 - f9 according to this serial number;

[0055] 4. Calculate the average value of the power corresponding to the frequencies within the range of data length 10 centered on this frequency, and compare it with the maximum value at this frequency (see Figure 2 ). If the absolute value is greater than 10, it is considered that there is frequent pitching. According to the axis relationship corresponding to the data, report "pitch oscillation of a certain axis" and execute the shutdown procedure.

[0056] Among them, preferably, the data acquisition duration is reasonably set to avoid the CPU and memory load caused by long - time data sampling. In this solution, data is sampled once every 10 ms, the data is all real numbers, the data length is 10 minutes. After processing, continue data acquisition and can overwrite the original data;

[0057] Preferably, the power spectral analysis uses the pwelch function, in the form of [Pxx, f] = pwelch(xn, window, noverlap, nfft, Fs). Pxx needs to be further processed by 10*log10(Pxx) and then saved to the variable. By setting Fs, the monitoring frequency range of the specified signal can be set;

[0058] Preferably, the comparison between the maximum value and the average value is carried out in a loop, see Figure 2 .

[0059] Specifically:

[0060] S1. Collect the positions, speeds, and currents of the three axes of the pitch system of the wind turbine every 10 minutes and save them to the variables Pos1 - Pos3, Spd1 - Spd3, Curr1 - Curr3;

[0061] S2. Perform power spectral density analysis on the above 9 array variables using Pwelch, save the frequencies to f1 - f9, and save the powers to P1 - P9;

[0062] S3. Use findpeaks to find the maximum values and their sequence numbers in P1 - P9. The maximum values are saved to Peak1 - Peak9, and the sequence numbers are saved to n.

[0063] S4. According to n, find the frequency values in f1 - f9, and calculate the average value of the power corresponding to the frequencies within a range of data length 10 centered on this frequency.

[0064] S5. The absolute value of the difference between the maximum value corresponding to this frequency and the average value > 10 dB.

[0065] S6. If so, the wind turbine reports the fault "pitch oscillation of a certain axis" and shuts down; if not, the wind turbine operates normally.

[0066] Through the monitoring of the position, speed, and current (or torque value) of the pitch system of the wind turbine, the present invention can effectively determine whether there is oscillation in the pitch system, report the fault, and execute the shutdown procedure for protection. It can effectively protect against frequent pitching caused by abnormal pitch position commands or external load alternation (such as vortex-induced vibration), and avoid further risks to the unit.

[0067] As described above, the present invention can be preferably implemented.

[0068] All the features disclosed in all the embodiments in this specification, or all the steps in the implicitly disclosed methods or processes, except for the mutually exclusive features and / or steps, can be combined and / or extended and replaced in any way.

[0069] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Based on the technical essence of the present invention, any simple modifications, equivalent replacements, and improvements made to the above embodiments within the spirit and principles of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A warning and protection method for the oscillation of a pitch system of a wind turbine, characterized in that, It includes the following steps: S1. Collect the operating data values of K categories of the three axes of the pitch system of the wind turbine generator set; S2. Conduct power spectral density analysis on the operating data values to obtain 3K groups of frequencies and their corresponding powers; S3. Select the maximum value of the power in each group; S4. Select the frequency corresponding to the maximum power, and calculate the average value of the powers corresponding to the frequencies within the range with the frequency as the center and the data length of N; S5. Calculate the absolute value of the difference between the maximum power corresponding to each frequency and the average power of that frequency, and compare the absolute value of the difference with the set threshold; S6. If the absolute value of the difference > the set threshold, give a wind turbine fault alarm and stop the machine; otherwise, the wind turbine operates normally.

2. The early warning and protection method for the oscillation of the pitch system of a wind turbine unit according to claim 1, characterized in that In step S1, K = 3, and the operating data values are the actual pitch angle, pitch rate, and motor current respectively.

3. The early warning and protection method for the oscillation of the pitch system of a wind turbine according to claim 2, wherein, In step S4, 3 ≤ N ≤ 10.

4. A warning and protection method for the oscillation of a pitch system of a wind turbine according to claim 3, characterized in that, In step S4, N = 10.

5. The early warning and protection method for the oscillation of a variable pitch system of a wind turbine according to claim 4, characterized in that, In step S6, when giving a wind turbine fault alarm, display the category of the axis of the pitch system where the fault occurs.

6. The early warning and protection method for the oscillation of a pitch system of a wind turbine according to claim 5, characterized in that, In step S6, when exceeding the threshold, give a stop command to control the pitch retraction of the unit.

7. A warning and protection method for the oscillation of a variable pitch system of a wind turbine according to claim 6, characterized in that, In step S5, the set threshold is 5 - 15 dB.

8. A warning and protection method for the oscillation of a pitch system of a wind turbine according to any one of claims 1 to 7, characterized in that, In step S1, it is set to collect the operating data values of the pitch system of the wind turbine generator set every t ms, where 1 ≤ t ≤ 20.

9. The early warning and protection method for the oscillation of a pitch system of a wind turbine according to claim 8, wherein, In step S1, the length of the collected data is T minutes, where 1 ≤ T ≤ 10.

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