Calculation method for rotating speed of impeller of wind turbine generator, variable-pitch driver and storage medium

Abstract

The invention discloses a wind turbine generator impeller rotating speed calculation method, a variable-pitch driver and a storage medium, and the method comprises the steps: carrying out the filtering processing of the torque data of a variable-pitch motor, and obtaining a time-torque curve of the variable-pitch motor; determining the time when the impeller rotates for a circle at the minimum grid-connected rotating speed of the impeller, setting the minimum sampling period of a variable pitch driver, establishing an array based on the time and the period, and storing the filtered torque data in the array; calculating the slope of the time-torque curve according to the array and obtaining an extreme point; the change period of the time-torque curve is obtained through the extreme point, and the impeller rotation period and the impeller rotation speed are obtained. The variable-pitch motor torque curve change rule and the impeller rotating speed synchronism are utilized, the impeller rotating speed is obtained through calculation based on the variable-pitch motor torque collected by the variable-pitch driver, a sensor does not need to be added in a rated mode, and cost control is facilitated; and interference of the sensor in a strong electromagnetic field environment can be avoided, and signal acquisition is accurate and reliable.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation, and in particular to a method for calculating the impeller rotation speed of a wind turbine, a pitch drive, and a storage medium. Background Art

[0002] The impeller rotation speed is a core parameter for the safe operation of a wind power generation unit. Its accurate measurement and effective control directly affect the safety of the unit. An impeller overspeed event may cause the wind power generation unit to get out of control, and in severe cases, even lead to accidents such as the tower of the unit collapsing. Therefore, the monitoring and control of the impeller rotation speed are crucial. The traditional method for measuring the impeller rotation speed is to test the installation bolts of the impeller main shaft by setting proximity switches, or to measure the rotation speed through an encoder installed at the tail of the slip ring. These solutions have high maintenance costs and are vulnerable to interference in a strong electromagnetic environment, resulting in measurement errors. Summary of the Invention

[0003] The purpose of the present invention is to propose an optimization method, a pitch drive, and a storage medium for yaw control in a wind farm to solve the problems existing in the prior art.

[0004] To achieve the above purpose, in a first aspect, the present invention proposes a method for calculating the impeller rotation speed of a wind turbine, including:

[0005] S1. Filter the torque data of the pitch motor to obtain the time-torque curve of the pitch motor;

[0006] S2. Determine the time for the impeller to rotate one week at the minimum grid connection speed of the impeller as the minimum sampling time period, set the sampling period of the pitch drive, establish an array based on the minimum sampling time period and the sampling period, and store the filtered torque data of the pitch motor in the array;

[0007] S3. Calculate the slope of the time-torque curve according to the array, and obtain the extreme points of the time-torque curve based on the slope;

[0008] S4. Obtain the change period of the time-torque curve through the extreme points;

[0009] S5. Obtain the impeller rotation period through the change period of the time-torque curve, and calculate the impeller rotation speed through the impeller rotation period.

[0010] Further, the step S1 specifically includes:

[0011] S11. Obtain the original torque curve of the pitch motor according to the torque data of the pitch motor;

[0012] S12. Adopt a first-order low-pass filter algorithm to filter the original pitch motor torque curve to obtain the pitch motor torque curve after low-pass filtering;

[0013] S13. Perform a moving average filter on the pitch motor torque curve after low-pass filtering to obtain the time-torque curve of the pitch motor.

[0014] Further, the specific steps of step S3 include:

[0015] S31. Calculate the variable step size slope of the time-torque curve;

[0016] S32. Mark the positions of the peaks and valleys in the time-torque curve according to the calculated slope.

[0017] Further, the marking of the positions of the peaks and valleys in the time-torque curve according to the calculated slope is specifically as follows: when the slope of the time-torque curve changes from positive to negative, this is the highest point of the curve, marked as a peak, and the data position at that time is stored; when the slope of the time-torque curve changes from negative to positive, this is the lowest point of the curve, marked as a valley, and the data position at this time is stored.

[0018] Further, the obtaining of the change period of the time-torque curve through the extreme points is specifically as follows: according to the change law of the sine curve, calculate twice the time interval between the highest point and the lowest point of the curve to obtain the change period of the time-torque curve.

[0019] In a second aspect, the present invention provides a pitch driver for a wind turbine, including a processor and a memory storing program instructions, and the processor is configured to execute the above method for calculating the rotational speed of the wind turbine impeller when executing the program instructions.

[0020] In a third aspect, the present invention provides a readable storage medium, on which program instructions are stored, and when the program instructions are executed by a processor, the above method for calculating the rotational speed of the wind turbine impeller is implemented.

[0021] The present invention utilizes the synchronization between the change law of the pitch motor torque curve and the rotational speed of the impeller, and derives the rotational speed of the impeller by calculating the period of the pitch motor torque curve. This method is based on the acquisition of the pitch motor torque by the current unit pitch driver, does not require additional sensors rated, is beneficial to controlling costs; and can avoid interference of sensors in a strong electromagnetic field environment, and the signal acquisition is accurate and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The following drawings of the present invention are used as a part of the present invention to understand the present invention. The embodiments and descriptions of the present invention are shown in the drawings to explain the device and principle of the present invention. In the drawings,

[0023] Figure 1 Flow chart of the calculation method for the impeller rotation speed of the wind turbine unit according to the embodiment of the present invention;

[0024] Figure 2 Schematic diagram of the azimuth angles of different positions of the wind turbine blades;

[0025] Figure 3 Schematic diagram of the original pitch motor torque curve according to the embodiment of the present invention;

[0026] Figure 4 Schematic diagram of the pitch motor torque curve after low-pass filtering according to the embodiment of the present invention;

[0027] Figure 5 Schematic diagram of the pitch motor torque curve after moving average filtering according to the embodiment of the present invention;

[0028] Figure 6 Schematic diagram of the comparison between the original pitch motor torque curve and the torque curve after filtering according to the embodiment of the present invention. Detailed implementation manners

[0029] Hereinafter, the present application will be described in more detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and do not limit the protection scope of the present application.

[0030] By analyzing the data of the analog quantities that change synchronously during the rotation of the impeller, it is concluded that the law of the change of the pitch motor torque changes approximately sinusoidally with the different blade rotation azimuth angles. Specifically, when the wind power generation unit is generating electricity normally, the blade will be subject to the aerodynamic thrust from the air flow, the centrifugal force generated by the rotation of the impeller, and the gravity of the blade itself. At different azimuth angles, the final result of the three-force synthesis acting on the torque of the pitch motor also shows obvious differences. As the impeller rotates, the force of the resultant force of a single blade acting on the pitch motor also changes regularly at different azimuth angles, and the change law of the pitch motor torque is proportional to the change of the impeller rotation speed. Therefore, the torque of the pitch motor shows a periodic change law. It is found through statistics that the pitch motor torque changes approximately sinusoidally. By calculating the sine wave period of the pitch motor torque curve, the impeller rotation speed can be deduced inversely. On this basis, the present invention provides a calculation method for the impeller rotation speed of a wind turbine unit.

[0031] As Figures 1-6 shown, the calculation method includes:

[0032] Step 1: Perform filtering processing on the pitch motor torque data to obtain the time-torque curve of the pitch motor.

[0033] Step 1 may specifically include the following steps:

[0034] S11. Obtain the original pitch motor torque curve based on the pitch motor torque data;

[0035] S12. Use a first-order low-pass filter algorithm to filter the original pitch motor torque curve to obtain the pitch motor torque curve after low-pass filtering;

[0036] Specifically, the formula of the first-order low-pass filter algorithm is: Yn = aXn+(1 - a)Yn-1

[0037] Where a is the filter coefficient, Xn is the current sampling value, Yn-1 is the previous filter output value, and Yn is the current filter output value;

[0038] Write a program in ST language of IEC61131-3 as follows:

[0039] Torque_low_pass_filter := Torque_act*Filter_factor+Torque_low_pass_filter*(1 - Filter_factor);

[0040] / / Torque_low_pass_filter is the motor torque after filtering

[0041] / / Torque_act is the current actual motor torque

[0042] / / Torque_low_pass_filter is the filtered value of the previous cycle

[0043] / / Filter_factor is the filter coefficient

[0044] S13. Perform a moving average filter on the pitch motor torque curve after low-pass filtering to obtain the time-torque curve of the pitch motor;

[0045] Specifically, use the data Torque_low_pass_filter processed by low-pass filtering in step S12 as the input of the moving average filter, and the output value Filter_Torque of the moving average filter is the final result after the above filtering process. The program code is as follows:

[0046]

[0047]

[0048] Since the wind turbine is subject to various interferences during operation, there are also abnormal points in the torque data of the pitch motor. First, a first-order low-pass filtering algorithm is used to filter the torque data of the pitch motor, filter out the abnormal points, and obtain a smoother torque curve of the pitch motor, which is convenient for accurately locating the inflection points of the curve; then a moving average filter is used. The principle is to regard N continuously collected data as a queue, put the newly sampled data at the end of the queue, discard the data at the head of the queue, and then average the N data to obtain the filtering result. The moving average filter can make the motor torque curve smoother, reduce the curve jitter, and avoid misjudging the inflection point during the calculation process. To ensure accurate calculation, this method first judges the power generation state of the unit. Only when the impeller is rotating and the unit is generating electricity, the storage of the torque data curve of the pitch motor and subsequent slope judgment and impeller speed calculation are started.

[0049] Step 2: Determine the time for the impeller to rotate one week at the minimum grid-connected speed of the impeller as the minimum sampling time period, set the sampling period of the pitch driver, establish an array based on the minimum sampling time period and the sampling period, and store the filtered torque data of the pitch motor in the array.

[0050] The specific program code is as follows:

[0051] VAR

[0052] Motor_Torque: ARRAY[1...750] OF REAL; / / Set the array to store torque values

[0053] END_VAR

[0054] FOR i := 1 TO 750 BY 1 DO

[0055] Motor_Torque[i] := Filter_Torque; / / Store the filtered torque into the array

[0056] END_FOR

[0057] Establishing an array based on the time for the impeller to rotate one week at the minimum grid-connected speed of the impeller, setting the sampling period of the pitch driver and storing the torque data of the corresponding number of points in the array can include the data of all speeds in the power generation state of the unit, thus ensuring the integrity of the pitch motor curve data within the impeller speed period and preventing misjudgment of the period.

[0058] Step 3: Calculate the slope of the time-torque curve according to the array, and obtain the extreme points of the time-torque curve based on the slope.

[0059] Step 3 can specifically include the following steps:

[0060] S31. Calculate the slope with variable step size for the time-torque curve;

[0061] Preferably, the slope K can be calculated at intervals of 1 cycle, 3 cycles, 5 cycles, and 10 cycles respectively. The calculation method is as follows:

[0062] K = (Torque new - Torque old ) / F * N

[0063] where F is the minimum sampling period for the PLC to collect data of the pitch drive set in step 2, and N is the number of data intervals;

[0064] The specific program code is as follows:

[0065] VAR

[0066] K1: ARRAY[1...749] OF REAL;

[0067] K3: ARRAY[1...747] OF REAL;

[0068] K5: ARRAY[1...745] OF REAL;

[0069] K10: ARRAY[1...740] OF REAL;

[0070] END_VAR

[0071] FOR i := 1 TO 750 BY 1 DO

[0072] K1[i] = (Motor_Torque[i + 1] - Motor_Torque[i]) / 10 * 1;

[0073] K3[i] = (Motor_Torque[i + 2] - Motor_Torque[i]) / 10 * 3;

[0074] K5[i] = (Motor_Torque[i + 4] - Motor_Torque[i]) / 10 * 5;

[0075] K10[i] = (Motor_Torque[i + 9] - Motor_Torque[i]) / 10 * 10;

[0076] By calculating the slope with variable step size for the time-torque curve to obtain the changing trend of the slope, the inflection point of the curve can be accurately located.

[0077] S32. Mark the positions of the peaks and valleys in the time-torque curve according to the calculated slope;

[0078] Specifically, when the slope of the time-torque curve changes from positive to negative, this is the highest point of the curve, marked as the peak (High_Point), and the data position at that time is stored; when the slope of the time-torque curve changes from negative to positive, this is the lowest point of the curve, marked as the valley (Low_Point), and the data position at this time is stored. The program code is as follows:

[0079] IF(K1[i - 1]>0 and K1[i]<0 and K3[i]<0 and K5[i]<0 and K10[i]<0) THEN

[0080] High_Point := i;

[0081] Else if(K1[i - 1]<0 and K1[i]>0 and K3[i]>0 and K5[i]>0 and K10[i]>0) THEN

[0082] Low_Point := i;

[0083] Step 4: Obtain the change period of the time-torque curve through the extreme points;

[0084] In the pitch motor torque curve, the peak (High_Point) records the value of the highest torque point, and the valley (Low_Point) records the value of the lowest torque point. In a sine curve, the time interval between the highest point and the lowest point is half a period. Therefore, the period of the time-torque curve of the pitch motor that is consistent with the change law of the sine curve is calculated according to the following formula:

[0085] T = 2 * (High_Point - Low_Point) * F

[0086] Where F is the minimum sampling period of the pitch driver set in Step 2.

[0087] Step 5: Obtain the impeller rotation period through the change period of the time-torque curve, and calculate the impeller rotation speed through the impeller rotation period.

[0088] As can be analyzed above, the impeller rotation period is consistent with the change period of the time-torque curve of the pitch motor. Therefore, the change period of the time-torque curve calculated in Step 4 is used as the impeller rotation period; according to the definition of rotational speed, the rotational speed n is the number of rotations per unit time. The impeller rotational speed of a wind turbine is usually calculated in rpm / min. Therefore, the calculation formula for the impeller rotational speed n is:

[0089] N = 60 / T

[0090] The pitch drive of the present invention stores the above program instructions. When the rotational speed of the impeller calculated according to the above method exceeds the preset range, the pitch drive performs corresponding pitch operations.

[0091] The above calculation method will be described below by taking a certain model as an example.

[0092] 1. According to the pitch motor torque data of the unit, the original pitch motor torque curve is obtained, as Figure 3 shown;

[0093] 2. Using a first-order low-pass filter algorithm, filter the original pitch motor torque curve shown in Figure 3 to obtain the pitch motor torque curve after low-pass filtering, as Figure 4 shown;

[0094] 3. Perform a moving average filter on the pitch motor torque curve after low-pass filtering to obtain the pitch motor torque curve after filtering processing, as Figure 5 shown;

[0095] 4. Plot the curves of the original pitch motor torque data and the data after two filtrations, as shown below Figure 6 shown. The pitch motor torque curve after filtering processing is consistent with the original value in trend and there is no lag;

[0096] 5. Assume that the minimum grid connection speed of this model is 8 rpm. Then the time for the impeller to rotate one week at this speed, that is, the minimum sampling time period, is 60 s / 8 = 7.5 s. Assuming that the sampling period of the pitch drive is 10 ms, an array of 750 points needs to be set to store the pitch motor torque data within the minimum sampling time period;

[0097] 6. Calculate the slope of the pitch motor torque curve, and obtain that the position of the time point of the trough (Low_Point) is 245 and the position of the time point of the peak (High_Point) is 618;

[0098] 7. Calculate the change period T of the pitch motor torque curve: T = 2*(618 - 245)*10 = 7460 ms = 7.46 s;

[0099] 8. Calculate the rotational speed of the impeller n = 60 / 7.46 = 8.04 rpm.

[0100] The present invention utilizes the synchronization between the variation law of the pitch motor torque curve and the impeller speed, and derives the impeller speed by calculating the period of the pitch motor torque curve. This method is based on the acquisition of the pitch motor torque by the current unit pitch drive, without the need to additionally install sensors ratedly, which is beneficial to controlling costs; and it can avoid the interference of sensors in a strong electromagnetic field environment, and the signal acquisition is accurate and reliable.

[0101] Those skilled in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner can depend on the specific application and design constraints of the technical solution. The skilled person can use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of the embodiments of the present disclosure.

[0102] The steps of the methods or algorithms described in combination with the embodiments disclosed herein can be directly implemented by hardware, software modules executed by a processor, or a combination of the two. The software modules can be placed in a random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the technical field.

[0103] In the embodiments disclosed herein, the disclosed methods, products (including but not limited to devices, equipment, etc.) can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units can be merely a logical function division, and there can be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the shown or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, and the indirect couplings or communication connections of the devices or units can be in an electrical, mechanical or other form.

[0104] Unless otherwise defined, the technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the technical field of the present invention. The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. Terms such as "portion" and "part" as used herein may refer to a single part or a combination of multiple parts. Terms such as "mounted" and "arranged" as used herein may mean that one component is directly attached to another component or that one component is attached to another component through an intermediate member. Features described in one embodiment herein may be applied alone or in combination with other features to another embodiment, unless the feature is not applicable or otherwise stated in that other embodiment.

[0105] The present invention has been described by the above embodiments, but it should be understood that the above embodiments are only for illustrative and explanatory purposes and are not intended to limit the present invention within the scope of the described embodiments. In addition, those skilled in the art can understand that the present invention is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the present invention, and these variations and modifications all fall within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalent scope.

Claims

1. A method for calculating the rotational speed of an impeller of a wind turbine, characterized in that, Including: S1. Filter the torque data of the pitch motor to obtain the time-torque curve of the pitch motor; S2. Determine the time for one rotation of the impeller at the minimum grid connection speed of the impeller as the minimum sampling time period, set the sampling period of the pitch driver, establish an array based on the minimum sampling time period and the sampling period, and store the filtered torque data of the pitch motor in the array; S3. Calculate the slope of the time-torque curve according to the array, and obtain the extreme points of the time-torque curve based on the slope; S4. Obtain the change period of the time-torque curve through the extreme points; S5. Obtain the impeller rotation period through the change period of the time-torque curve, and calculate the impeller speed through the impeller rotation period.

2. The calculation method of the impeller rotation speed of a wind turbine according to claim 1, characterized in that, The specific steps of step S1 include: S11. Obtain the original torque curve of the pitch motor according to the torque data of the pitch motor; S12. Use a first-order low-pass filter algorithm to filter the original torque curve of the pitch motor to obtain the low-pass filtered torque curve of the pitch motor; S13. Perform moving average filtering on the low-pass filtered torque curve of the pitch motor to obtain the time-torque curve of the pitch motor.

3. The calculation method of the impeller rotation speed of the wind turbine according to claim 1, characterized in that, The specific steps of step S3 include: S31. Calculate the slope with variable step size for the time-torque curve; S32. Mark the positions of the peaks and valleys in the time-torque curve according to the calculated slope.

4. The calculation method of the impeller rotation speed of a wind turbine according to claim 3, characterized in that The marking of the positions of the peaks and valleys in the time-torque curve according to the calculated slope is specifically as follows: when the slope of the time-torque curve changes from positive to negative, this is the highest point of the curve, marked as a peak, and the data position at that time is stored; when the slope of the time-torque curve changes from negative to positive, this is the lowest point of the curve, marked as a valley, and the data position at this time is stored.

5. The calculation method of the impeller rotation speed of a wind turbine according to claim 4, characterized in that The obtaining of the change period of the time-torque curve through the extreme points is specifically as follows: according to the change law of the sine curve, calculate twice the time interval between the highest point and the lowest point of the curve to obtain the change period of the time-torque curve.

6. A pitch drive for a wind turbine, characterized in that, Including a processor and a memory storing program instructions, the processor is configured to execute the calculation method for the impeller speed of a wind turbine unit as described in any one of claims 1-5 when executing the program instructions.

7. A readable storage medium, characterized in that, Program instructions are stored on the readable storage medium, and when the program instructions are executed by the processor, the calculation method for the impeller speed of a wind turbine unit as described in any one of claims 1-5 is implemented.

Images