Control system and method for yaw error of wind turbine generator set under extreme wind conditions

Abstract

The present invention belongs to the technical field of wind turbine shutdown, and relates to a control system and method for yaw error of a wind turbine under extreme wind conditions. The control method comprises the following steps: a first step: calculating the current average yaw error; determining whether the current average yaw error exceeds a yaw error threshold, and if so, proceeding to a second step; a second step: calculating the current average pitch angle; determining whether the current average pitch angle exceeds a pitch angle threshold, and if so, proceeding to a third step; a third step: lowering the yaw error threshold; a fourth step: gradually reducing the impeller speed; a fifth step: calculating the current average impeller speed in real time during the impeller speed reduction process; determining whether the current average impeller speed exceeds a shutdown speed limit, and if so, entering a normal shutdown mode for the unit; and if not, maintaining the impeller speed at a set lower speed reduction limit. The method of the present invention can reduce the extreme load encountered by the wind turbine and reduce the design size of large components of the unit.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind turbine generator set shutdown, and particularly relates to a control system and method for controlling a yaw error of a wind turbine generator set under extreme wind conditions. Background Art

[0002] The rotor of a horizontal-axis wind turbine absorbs wind energy and rotates, in turn driving the connected generator to generate electricity. The turbine's yaw system uses a yaw mechanism to adjust its windward angle based on measured wind direction, keeping the rotor's swept surface perpendicular to the wind direction. This means aiming for zero yaw error to maximize wind energy absorption.

[0003] However, in some extreme wind conditions, the extreme loads on the turbine are detrimental to the operation of the wind turbine. Therefore, it is necessary to adjust the yaw control strategy to minimize the load on the turbine in extreme wind conditions such as strong wind direction and speed changes.

[0004] The existing yaw control strategy is to shut down the wind turbine for protection when the yaw deviation exceeds a threshold. Therefore, when the wind turbine encounters extreme wind conditions such as rapid and large-scale changes in wind direction, the measured yaw error exceeds the specified limit. The controller will shut down the turbine according to the yaw control strategy, and the turbine will experience extreme loads.

[0005] When a wind turbine encounters extreme conditions of large wind direction and speed changes, large yaw errors can lead to extreme loads, which are detrimental to turbine operation. Therefore, it is necessary to adjust the yaw control strategy to reduce turbine loads and increase turbine headroom. Summary of the Invention

[0006] The purpose of the present invention is to provide a control system and method for yaw error of a wind turbine generator set under extreme wind conditions, which solves the problem that the wind turbine generator set will experience extreme loads when encountering extreme wind conditions.

[0007] The present invention is achieved through the following technical solutions:

[0008] A method for controlling the yaw error of a wind turbine generator set under extreme wind conditions comprises the following steps:

[0009] Step 1: Calculate the current average yaw error;

[0010] Determine whether the current average yaw error exceeds the yaw error threshold. If yes, proceed to step 2; if not, terminate the yaw control strategy.

[0011] Step 2: Calculate the current average pitch angle;

[0012] Determine whether the current average pitch angle exceeds the pitch angle threshold. If yes, proceed to step 3; if not, terminate the yaw control strategy.

[0013] Step 3: Lower the yaw error threshold;

[0014] Step 4: The impeller speed gradually decreases;

[0015] Step 5: When the impeller speed decreases, calculate the current average impeller speed in real time;

[0016] Determine whether the current average impeller speed exceeds the shutdown speed limit. If so, the unit enters normal shutdown mode. If not, the impeller speed will be maintained at the set speed reduction lower limit.

[0017] Furthermore, in the first step, the current average yaw error is calculated as follows:

[0018] Detect the current yaw error and the yaw error within the current t1 second, and average them to obtain the current average yaw error.

[0019] Furthermore, t1 is set to 1-5 seconds.

[0020] Furthermore, in the second step, the current average pitch angle is calculated as follows:

[0021] The current pitch angle and the pitch angle within t2 seconds of the current pitch angle are detected and averaged to obtain the current average pitch angle.

[0022] Furthermore, t2 is set to 1-5 seconds.

[0023] Furthermore, in the fifth step, the current average impeller speed is calculated as follows:

[0024] The current impeller speed and the speed within t3 seconds of the current impeller speed are detected and averaged to obtain the current average impeller speed.

[0025] Furthermore, t3 is set to 1-5 seconds.

[0026] Furthermore, in the first step, a notch filter or a low-pass filter is used to obtain the current average yaw error;

[0027] In the second step, notch filtering or low-pass filtering is used to obtain the current average pitch angle;

[0028] In the fifth step, notch filtering or low-pass filtering is used to obtain the current average impeller speed.

[0029] Furthermore, in the fourth step, the impeller speed is gradually decreased at a fixed slope, and the target of the impeller speed decrease is set to the impeller speed decrease target value Ωlow.

[0030] The present invention also discloses a control system for yaw error of a wind turbine generator set under extreme wind conditions, comprising:

[0031] A storage module, used for storing a yaw error threshold, a pitch angle threshold, a shutdown speed limit, and a speed reduction lower limit;

[0032] The average yaw error calculation module is used to calculate the current average yaw error;

[0033] A first comparison module is used to determine whether the current average yaw error exceeds the yaw error threshold, and if so, to start the average pitch angle calculation module; if not, the yaw control strategy is terminated;

[0034] The average pitch angle calculation module is used to calculate the current average pitch angle;

[0035] A second comparison module is used to determine whether the current average pitch angle exceeds the pitch angle threshold, and if so, to lower the yaw error threshold; if not, the yaw control strategy is terminated;

[0036] Impeller descent adjustment module, used to reduce the impeller speed;

[0037] The average impeller speed module is used to calculate the current average impeller speed in real time during the impeller speed decrease process;

[0038] The third comparison module is used to determine whether the current average impeller speed exceeds the shutdown speed limit. If so, the unit enters normal shutdown mode. If not, the impeller speed will be maintained at the set speed reduction lower limit.

[0039] Compared with the prior art, the present invention has the following beneficial technical effects:

[0040] The present invention discloses a method for controlling the yaw error of a wind turbine generator set under extreme wind conditions. The method adopts the detection of yaw deviation and pitch angle as the conditional input for judging extreme gusts, which can reduce the load on the set caused by large yaw errors due to extreme wind conditions; the threshold is lowered because it is considered that the original set threshold is exceeded, indicating that problems have occurred in the yaw software and hardware. In order to further protect the set from a series of problems caused by large yaw deviation, the yaw deviation threshold is lowered, the set is further protected, and protective actions are performed in advance; the force on the set is reduced by reducing the impeller speed, and the load on the fixed hub can be effectively reduced by reducing the yaw speed.

[0041] Compared with the normal shutdown method triggered by a large yaw error, the present invention can effectively increase the tower clearance of the unit by reducing the rotational speed during yaw. The reduction of the ultimate load encountered by the wind turbine can help the structural design of the wind turbine, thereby reducing manufacturing costs. With the development trend of large-capacity and large-blade and high-tower designs of wind turbines, the method of the present invention can reduce the ultimate load in the design stage and reduce the design size of large components of the unit. The yaw deviation exceeding the threshold indicates that the unit is experiencing extreme wind conditions. At this time, reducing the rotational speed can avoid serious accidents such as overspeed, blade sweeping the tower, or unit overturning to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The present invention is a flow chart of a method for controlling yaw error of a wind turbine generator set under extreme wind conditions. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the present invention more clear, the following is a further detailed description with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. That is, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments.

[0044] The components described and illustrated in the drawings and embodiments of the present invention may be arranged and designed in a variety of different configurations. Therefore, the detailed description of the embodiments of the present invention provided in the following drawings is not intended to limit the scope of the claimed invention, but merely represents a selected embodiment of the present invention. All other embodiments derived by those skilled in the art based on the drawings and embodiments of the present invention without inventive effort shall fall within the scope of protection of the present invention.

[0045] It should be noted that the terms "comprises", "includes" or any other variations are intended to cover non-exclusive inclusion, so that a process, element, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to the process, element, method, article or apparatus.

[0046] like Figure 1 As shown, the present invention discloses a method for controlling the yaw error of a wind turbine generator set under extreme wind conditions, comprising the following steps:

[0047] Step 1: Use time averaging, notch filtering or low-pass filtering to obtain the current average yaw error;

[0048] Determine whether the current average yaw error exceeds the yaw error threshold Δ1. If so, proceed to step 2. If not, terminate the yaw control strategy without further action.

[0049] Step 2: Use time averaging, notch filtering or low-pass filtering to obtain the current average pitch angle;

[0050] Determine whether the current average pitch angle exceeds the pitch angle threshold β1. If yes, proceed to the third step; if not, this yaw control strategy is terminated without further operation.

[0051] Step 3: The yaw error threshold is reduced from Δ1 to Δ2. The reason for lowering the threshold is that it exceeds the original set threshold, indicating that there are problems with the yaw software and hardware. In order to further protect the unit from a series of problems caused by large yaw deviation, the yaw deviation threshold is lowered to further protect the unit and protective action is taken in advance.

[0052] Step 4: The impeller speed gradually decreases, and the downward transition process should be smooth and gentle, generally with a fixed slope limit.

[0053] The target of the impeller speed reduction is set to the impeller speed reduction target value Ωlow;

[0054] Step 5: Use time averaging, notch filtering or low-pass filtering to obtain the current average impeller speed;

[0055] Determine whether the current average impeller speed exceeds the shutdown speed limit Ωstop. If so, the unit enters normal shutdown mode. If not, the impeller speed will be maintained at the set speed reduction lower limit Ω.

[0056] The impeller speed reduction target value Ωlow is below the shutdown speed limit Ωstop.

[0057] The normal shutdown here is a routine operation in which the unit stops running. Generally, the blades begin to retract to 90 degrees, and the power of the wind turbine generator set gradually decreases to 0.

[0058] The yaw control method of a wind turbine generator set according to an embodiment of the present invention is described in detail below with reference to the accompanying drawings.

[0059] Example 1

[0060] like Figure 1 As shown, the present invention discloses a method for controlling the yaw error of a wind turbine generator set under extreme wind conditions, comprising the following steps:

[0061] Step 1: Detect the current yaw error and average it for 3 seconds to get the current average yaw error;

[0062] Detect the current pitch angle and average it for 3 seconds to get the current average pitch angle;

[0063] Detect the current impeller speed and average it for 5 seconds to get the current average impeller speed;

[0064] Step 2: Determine whether the current average yaw error exceeds the set yaw error threshold Δ1. If yes, proceed to step 3; if not, terminate the yaw control strategy without further operation.

[0065] Step 3: Determine whether the current average pitch angle exceeds the set pitch angle threshold β1. If yes, proceed to step 4. If not, this yaw control strategy is terminated without further operation.

[0066] Step 4: The yaw error threshold is reduced from Δ1 to Δ2;

[0067] Step 5: The impeller speed gradually decreases, and the downward transition process should be smooth and gentle. Generally, it is set to gradually decrease to the impeller speed reduction target value Ωlow with a fixed slope limit.

[0068] Because it has been determined in the third step that the current average pitch angle exceeds the set pitch angle threshold β1, it means that there is currently a strong wind state, and the unit is protected by reducing the impeller speed.

[0069] Step 6: During the process of impeller speed decreasing, determine in real time whether the current average impeller speed exceeds the shutdown speed limit Ωstop. If yes, the unit enters normal shutdown mode. If not, the impeller speed will be maintained at the set speed reduction lower limit Ω.

[0070] The definitions and specific values of Δ1, Δ2, β1, Ω, Ωstop, and Ωlow are shown in Tables 1 and 2.

[0071] Table 1 Rated speed of the unit and lower limit of set speed reduction

[0072] Rated speed Lower speed limit Shutdown speed limit Impeller speed reduction target value Ωrated=13.5rpm Ω=11.5rpm Ωstop=10rpm Ωlow=9rpm

[0073] Table 2 Set yaw error and corresponding pitch angle threshold

[0074] Yaw error Pitch angle Δ1=50° β1＝4° Δ2=40°

[0075] Example 2

[0076] like Figure 1 As shown, the present invention discloses a method for controlling the yaw error of a wind turbine generator set under extreme wind conditions, comprising the following steps:

[0077] Step 1: Detect the current yaw error and perform 1-second averaging to obtain the current average yaw error;

[0078] Step 2: Determine whether the current average yaw error exceeds the set yaw error threshold Δ1. If yes, proceed to step 3; if not, terminate the yaw control strategy without further operation.

[0079] Step 3: Detect the current pitch angle and perform 1-second averaging to obtain the current average pitch angle;

[0080] Determine whether the current average pitch angle exceeds the set pitch angle threshold β1. If yes, proceed to step 4. If not, this yaw control strategy is terminated without further operation.

[0081] Step 4: The yaw error threshold is reduced from Δ1 to Δ2 after multiple steps;

[0082] Step 5: The impeller speed gradually decreases, and the downward transition process should be smooth and gentle, generally with a fixed slope limit.

[0083] Step 6: Detect the current impeller speed and perform 1-second averaging to obtain the current average impeller speed;

[0084] Determine whether the current average impeller speed exceeds the shutdown speed limit Ωstop. If so, the unit enters normal shutdown mode. If not, the impeller speed will be maintained at the set speed reduction lower limit Ω.

[0085] The definitions and specific values of Δ1, Δ2, β1, Ω, Ωstop, and Ωlow are shown in Tables 1 and 2.

[0086] Example 3

[0087] like Figure 1 As shown, the present invention discloses a method for controlling the yaw error of a wind turbine generator set under extreme wind conditions, comprising the following steps:

[0088] Step 1: Detect the current yaw error and average it for 5 seconds to get the current average yaw error;

[0089] Step 2: Determine whether the current average yaw error exceeds the set yaw error threshold Δ1. If yes, proceed to step 3; if not, terminate the yaw control strategy without further operation.

[0090] Step 3: Detect the current pitch angle and average it for 5 seconds to obtain the current average pitch angle;

[0091] Determine whether the current average pitch angle exceeds the set pitch angle threshold β1. If yes, proceed to step 4. If not, this yaw control strategy is terminated without further operation.

[0092] Step 4: The yaw error threshold is reduced from Δ1 to Δ2;

[0093] Step 5: The impeller speed gradually decreases, and the downward transition process should be smooth and gentle, generally with a fixed slope limit.

[0094] Step 6: Detect the current impeller speed and average it for 5 seconds to get the current average impeller speed;

[0095] Determine whether the current average impeller speed exceeds the shutdown speed limit Ωstop. If so, the unit enters normal shutdown mode. If not, the impeller speed will be maintained at the set speed reduction lower limit Ω.

[0096] The definitions and specific values of Δ1, Δ2, β1, Ω, Ωstop, and Ωlow are shown in Tables 1 and 2.

[0097] Example 4

[0098] like Figure 1 As shown, the present invention discloses a method for controlling the yaw error of a wind turbine generator set under extreme wind conditions, comprising the following steps:

[0099] Step 1: Use notch filtering to obtain the current average yaw error after filtering;

[0100] Step 2: Determine whether the current average yaw error exceeds the set yaw error threshold Δ1. If yes, proceed to step 3; if not, terminate the yaw control strategy without further operation.

[0101] Step 3: Use notch filtering to obtain the filtered current average pitch angle;

[0102] Determine whether the current average pitch angle exceeds the set pitch angle threshold β1. If yes, proceed to step 4. If not, this yaw control strategy is terminated without further operation.

[0103] Step 4: The yaw error threshold is reduced from Δ1 to Δ2;

[0104] Step 5: The impeller speed gradually decreases, and the downward transition process should be smooth and gentle, generally with a fixed slope limit.

[0105] Step 6: Use notch filtering to obtain the current average impeller speed after filtering;

[0106] Determine whether the current average impeller speed exceeds the shutdown speed limit Ωstop. If so, the unit enters normal shutdown mode. If not, the impeller speed will be maintained at the set speed reduction lower limit Ω.

[0107] The definitions and specific values of Δ1, Δ2, β1, Ω, Ωstop, and Ωlow are shown in Tables 1 and 2.

[0108] A notch filter is a filter that rapidly attenuates the input signal at a specific frequency, effectively preventing the signal at that frequency from passing through. A notch filter is a type of band-stop filter, but its stopband is very narrow, and its order must be second-order or higher.

[0109] Example 5

[0110] like Figure 1 As shown, the present invention discloses a method for controlling the yaw error of a wind turbine generator set under extreme wind conditions, comprising the following steps:

[0111] Step 1: Use low-pass filtering to obtain the current average yaw error after filtering;

[0112] Step 2: Determine whether the current average yaw error exceeds the set yaw error threshold Δ1. If yes, proceed to step 3; if not, terminate the yaw control strategy without further operation.

[0113] Step 3: Use low-pass filtering to obtain the filtered current average pitch angle;

[0114] Determine whether the current average pitch angle exceeds the set pitch angle threshold β1. If yes, proceed to step 4. If not, this yaw control strategy is terminated without further operation.

[0115] Step 4: The yaw error threshold is reduced from Δ1 to Δ2;

[0116] Step 5: The impeller speed gradually decreases, and the downward transition process should be smooth and gentle, generally with a fixed slope limit.

[0117] Step 6: Use low-pass filtering to obtain the current average impeller speed after filtering;

[0118] Determine whether the current average impeller speed exceeds the shutdown speed limit Ωstop. If so, the unit enters normal shutdown mode. If not, the impeller speed will be maintained at the set speed reduction lower limit Ω.

[0119] The definitions and specific values of Δ1, Δ2, β1, Ω, Ωstop, and Ωlow are shown in Tables 1 and 2.

[0120] Low-pass filtering sets a frequency point. When the signal frequency is higher than this frequency, it cannot pass. In digital signals, this frequency point is also the cutoff frequency. When the frequency domain is higher than this cutoff frequency, all values are assigned to 0. Because this process allows all low-frequency signals to pass, it is called low-pass filtering.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for controlling the yaw error of a wind turbine generator set under extreme wind conditions, characterized in that: The following steps are involved: Step 1: Calculate the current average yaw error; Determine whether the current average yaw error exceeds the yaw error threshold. If yes, proceed to step 2; if not, terminate the yaw control strategy. Step 2: Calculate the current average pitch angle; Determine whether the current average pitch angle exceeds the pitch angle threshold. If yes, proceed to step 3; if not, terminate the yaw control strategy. Step 3: Lower the yaw error threshold; Step 4: The impeller speed gradually decreases; Step 5: When the impeller speed decreases, calculate the current average impeller speed in real time; Determine whether the current average impeller speed exceeds the shutdown speed limit. If so, the unit enters normal shutdown mode. If not, the impeller speed will be maintained at the set speed reduction lower limit.

2. The method for controlling the yaw error of a wind turbine generator set under extreme wind conditions according to claim 1, characterized in that: In the first step, the current average yaw error is calculated as follows: Detect the current yaw error and the yaw error within the current t1 second, and average them to obtain the current average yaw error.

3. The method for controlling the yaw error of a wind turbine generator set under extreme wind conditions according to claim 2, characterized in that: t1 is 1-5 seconds.

4. The method for controlling the yaw error of a wind turbine generator set under extreme wind conditions according to claim 1, characterized in that: In the second step, the current average pitch angle is calculated as follows: The current pitch angle and the pitch angle within t2 seconds of the current pitch angle are detected and averaged to obtain the current average pitch angle.

5. The method for controlling the yaw error of a wind turbine generator set under extreme wind conditions according to claim 4, characterized in that: t2 is 1-5 seconds.

6. The method for controlling yaw error of a wind turbine generator set under extreme wind conditions according to claim 1, characterized in that: In the fifth step, the current average impeller speed is calculated as follows: The current impeller speed and the speed within t3 seconds of the current impeller speed are detected and averaged to obtain the current average impeller speed.

7. The method for controlling the yaw error of a wind turbine generator set under extreme wind conditions according to claim 6, characterized in that: t3 is 1-5 seconds.

8. The method for controlling yaw error of a wind turbine generator set under extreme wind conditions according to claim 1, characterized in that: In the first step, the current average yaw error is obtained by using notch filtering or low-pass filtering; In the second step, notch filtering or low-pass filtering is used to obtain the current average pitch angle; In the fifth step, notch filtering or low-pass filtering is used to obtain the current average impeller speed.

9. The method for controlling yaw error of a wind turbine generator set under extreme wind conditions according to claim 1, characterized in that: In the fourth step, the impeller speed gradually decreases at a fixed slope, and the target of the impeller speed decrease is set to the impeller speed decrease target value Ωlow.

10. A control system for yaw error of a wind turbine generator set under extreme wind conditions, implementing the control method according to any one of claims 1 to 9, characterized in that: include: A storage module, used for storing a yaw error threshold, a pitch angle threshold, a shutdown speed limit, and a speed reduction lower limit; The average yaw error calculation module is used to calculate the current average yaw error; a first comparison module, configured to determine whether the current average yaw error exceeds a yaw error threshold, and if so, start the average pitch angle calculation module; If not, the yaw control strategy is terminated; The average pitch angle calculation module is used to calculate the current average pitch angle; a second comparison module, configured to determine whether the current average pitch angle exceeds a pitch angle threshold, and if so, to lower the yaw error threshold; If not, the yaw control strategy is terminated; Impeller descent adjustment module, used to reduce the impeller speed; The average impeller speed module is used to calculate the current average impeller speed in real time during the impeller speed decrease process; The third comparison module is used to determine whether the current average impeller speed exceeds the shutdown speed limit. If so, the unit enters normal shutdown mode. If not, the impeller speed will be maintained at the set speed reduction lower limit.

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