Pitch control method, pitch control device and wind turbine generator set

Abstract

Disclosed are a pitch control method, a pitch control device and a wind turbine generator set. The pitch control method comprises: obtaining a target rotational speed and an actual rotational speed of the wind turbine generator set, and calculating a rotational speed difference between the target rotational speed and the actual rotational speed of the wind turbine generator set; calculating a first pitch control variable of the wind turbine generator set based on the rotational speed difference; obtaining a rated wind speed and an actual wind speed of the wind turbine generator set, and calculating a wind speed difference between the rated wind speed and the actual wind speed of the wind turbine generator set; calculating a second pitch control variable of the wind turbine generator set based on the wind speed difference; and controlling the operation of a pitch motor of the wind turbine generator set according to the first pitch control variable and the second pitch control variable.

Description

Technical Field

[0001] The present disclosure generally relates to the field of wind power generation technology, and more specifically, to a pitch control method, a pitch control device and a wind generator set that can effectively match wind speed changes to maintain a stable rotation speed of a wind generator set. Background Art

[0002] For wind turbines, the two most core controls are torque control and pitch angle control. In order to improve the accuracy of torque control and pitch angle control and simplify the model, the most commonly used control method is PID (proportional differential integral) control, more specifically, PI (proportional integral) control. Here, the purpose of torque control is to make the wind turbine execute the most reasonable torque value according to the current speed value to achieve maximum power tracking. If the torque value overshoots or the response time is slow, it will reduce the wind energy utilization coefficient of the wind turbine and reduce the power generation of the wind turbine.

[0003] With the continuous increase in the capacity of wind turbines, how to ensure the efficient and stable operation of wind turbines has become an important part of wind power technology research. The variable pitch variable speed constant frequency control strategy is a hot topic of research. However, due to the lack of understanding of the operating conditions and wind conditions of wind turbines, the operation of wind turbines cannot meet the requirements of stable speed. An important reason is that the current variable pitch control of wind turbines is mainly the above-mentioned PI control, that is, the main control system calculates the pitch angle value and transmits it to the variable pitch system by making the wind turbine run at a constant speed as the control target, and the variable pitch system changes the pitch according to the latest angle command. This method can achieve constant speed control to a certain extent, but it also has the following disadvantages.

[0004] First, since the wind speed is transient, the use of PI control alone has certain limitations on the speed stabilization effect. Secondly, PI control is based on the target difference, that is, the calculation and pitch change are performed only after the speed difference change is detected, which has hysteresis. Third, when the wind turbine generator set operates above the rated wind speed, the fluctuation of the speed will cause a large load and affect the life of the wind turbine generator set. Fourth, since the PI control has hysteresis as mentioned above, when the wind speed suddenly increases, the wind turbine generator set is prone to overspeed, which will lead to the following situations: First, the generator speed is too high, which will increase the fatigue load of the wind turbine generator set; second, the generator runs at a high speed for a long time, which will cause serious loss of the wind turbine generator set and reduce its service life; third, it is easy to trigger an overspeed fault and shut down. Fifth, since the PI control has hysteresis as mentioned above, when the wind speed suddenly decreases, the wind turbine generator set is prone to frequent switching between the constant power zone and the constant speed zone, and when the wind turbine generator set switches from the constant power zone to the constant speed zone, the torque value will decrease, resulting in a decrease in power generation efficiency and affecting the power generation of the wind turbine generator set. Summary of the invention

[0005] Therefore, the embodiments of the present disclosure provide a pitch control method and a pitch control device to make the pitch adjustment law of a wind turbine generator set closer to the wind speed variation law, thereby achieving early pitch adjustment and stabilizing the generator speed.

[0006] In a general aspect, a pitch control method is provided, the pitch control method comprising: obtaining a target rotational speed and an actual rotational speed of a wind turbine, and calculating a rotational speed difference between the target rotational speed and the actual rotational speed of the wind turbine; calculating a first pitch control variable of the wind turbine based on the rotational speed difference; obtaining a rated wind speed and an actual wind speed of the wind turbine, and calculating a wind speed difference between the rated wind speed and the actual wind speed of the wind turbine; calculating a second pitch control variable of the wind turbine based on the wind speed difference; and controlling the operation of a pitch motor of the wind turbine according to the first pitch control variable and the second pitch control variable.

[0007] In another general aspect, a pitch control device for a wind turbine is provided, the pitch control device comprising: a speed difference calculation unit, configured to obtain a target speed and an actual speed of the wind turbine, and calculate the speed difference between the target speed and the actual speed of the wind turbine; a first pitch control variable calculation unit, configured to calculate a first pitch control variable of the wind turbine based on the speed difference; a wind speed difference calculation unit, configured to obtain a rated wind speed and an actual wind speed of the wind turbine, and calculate the wind speed difference between the rated wind speed and the actual wind speed of the wind turbine; a second pitch control variable calculation unit, configured to calculate a second pitch control variable of the wind turbine based on the wind speed difference; and a control unit, configured to control the operation of a pitch motor of the wind turbine according to the first pitch control variable and the second pitch control variable.

[0008] In another general aspect, a computer-readable storage medium storing a computer program is provided, and when the computer program is executed by a processor, the pitch control method as described above is implemented.

[0009] In another general aspect, a pitch control device is provided, comprising: a processor; and a memory storing a computer program, wherein when the computer program is executed by the processor, the pitch control method as described above is implemented.

[0010] In another general aspect, a wind turbine generator set is provided, the wind turbine generator set comprising the pitch control device as described above.

[0011] According to the variable pitch control method, variable pitch control device and wind turbine generator set disclosed in the present invention, the variable pitch control of the wind turbine generator set is realized by considering the dual effects of the rotational speed and the wind speed and utilizing the feedforward function of the differential, so that the variable pitch control can match the wind speed change, thereby maintaining the stability of the rotational speed of the wind turbine generator set and effectively avoiding the problem of pitch angle overshoot. On the other hand, since the variable pitch control method according to the embodiment of the present invention is executed only when the rotational speed of the wind turbine generator set reaches the rated rotational speed, the fluctuation of the electromagnetic torque of the generator in the constant power region can be reduced. At the same time, since the variable pitch control method and the variable pitch control device according to the embodiment of the present invention realize the stable control of the rotational speed of the wind turbine generator set, the vibration of the wind turbine generator set can be reduced.

[0012] Additional aspects and / or advantages of the present general inventive concept will be set forth in part in the following description and in part will be apparent from the description or may be learned through practice of the present general inventive concept. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above and other objects and features of the embodiments of the present disclosure will become more apparent through the following description in conjunction with the accompanying drawings showing the embodiments, in which:

[0014] Figure 1 is a schematic diagram showing the operating area of ​​a wind turbine generator set;

[0015] Figure 2 is a graph showing the wind speed, the given rotation speed (ie, the target rotation speed) and the actual rotation speed of the wind turbine generator set when the existing PI controller is used to perform the pitch control method;

[0016] Figure 3 is a flow chart showing a pitch control method according to an embodiment of the present disclosure;

[0017] Figure 4 is a diagram showing an application example of a pitch control method according to an embodiment of the present disclosure;

[0018] Figure 5 is a block diagram showing a pitch control device according to an embodiment of the present disclosure;

[0019] Figure 6 is a simulation schematic diagram showing a pitch control method according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0020] The following specific embodiments are provided to help the reader obtain a comprehensive understanding of the methods, devices and / or systems described herein. However, after understanding the disclosure of the present application, various changes, modifications and equivalents of the methods, devices and / or systems described herein will be clear. For example, the order of operations described herein is only an example and is not limited to those orders set forth herein, but can be changed as will be clear after understanding the disclosure of the present application, except for operations that must occur in a specific order. In addition, for greater clarity and simplicity, the description of features known in the art may be omitted.

[0021] In order to achieve the stability of wind turbine operation (for example, to maintain the stability of wind turbine speed), it is particularly important to consider the influence of wind speed in pitch control. However, the two commonly used wind speed prediction methods, namely, wind speed prediction through weather forecast information and wind measurement using front wind speed sensors, both have serious shortcomings. For the first prediction method, the blindness is too high, and the predicted wind speed value is not accurate enough to serve as the basis for pitch control. For the second prediction method, since the pitch hub is rotating, the installation of the wind speed sensor is limited, and the addition of slip ring equipment is likely to cause data interference and instability. In addition, if the wind speed sensor is installed at the tail of the nacelle, it is required to measure at a farther distance, resulting in increased costs and is not suitable for a single wind turbine.

[0022] On the other hand, PID (proportional integral differential) is still the most widely used industrial controller because the controller is simple and easy to understand, and does not require accurate system models and other prerequisites during use. In wind turbines, the commonly used PID controllers are the "speed-torque" PI (proportional integral) controller (adjusting the torque value of the wind turbine according to the input generator speed value) and the "speed-pitch speed" PI controller (adjusting the pitch angle according to the input generator speed value), among which the "speed-pitch speed" PI controller is used for pitch control. However, adjusting the pitch angle based on the speed value alone will inevitably produce a certain lag. The reason is that after the wind speed changes, according to the physical formula F=ma, due to the large moment of inertia of the impeller, the wind force acting on the blade will take a certain amount of time to change the impeller speed, and the PI controller will start the pitch control only after the impeller speed changes.

[0023] According to the embodiments of the present disclosure, taking into account the operating characteristics of the wind turbine and the feedforward effect of differential control, a differential feedforward control based on wind speed is added on the basis of the "rotation speed-pitch speed" PI controller of the pitch system, so that the pitch law is closer to the wind speed change law, thereby achieving the effects of early pitch change and stabilizing the generator speed.

[0024] Refer to the following Figures 1 to 6 A pitch control method and a pitch control device according to an embodiment of the present disclosure are described in detail.

[0025] Figure 1 is a schematic diagram showing the operating area of ​​a wind turbine generator system.

[0026] Reference Figure 1 The operation area of ​​a wind turbine generator set can generally be divided into four operation areas: a start-up area 101, a Cp (wind energy utilization coefficient) constant area, a speed constant area 103, and a power constant area 104. The pitch control method according to the embodiment of the present disclosure mainly performs pitch control in advance for the operation in the power constant area 104 (i.e., the C-D operation area in the figure), thereby solving the following problems currently faced by wind turbine generator sets: transient wind speed, low precision of the PI control method; passive pitch control causes pitch lag, causing speed control to fluctuate, which in turn causes the load of the unit to increase, and even produces overspeed when the wind speed is above the rated wind speed, and when the wind speed occasionally decreases, the unit frequently switches between the two control areas, resulting in low power generation.

[0027] like Figure 1 The division method of the operating area of ​​the wind turbine generator set shown is a division method commonly used by those skilled in the art and will not be described in detail here.

[0028] Figure 2It is a graph showing the wind speed, the given rotation speed (ie, the target rotation speed) and the actual rotation speed of the wind turbine generator set when the conventional PI controller is applied to execute the pitch control method.

[0029] Reference Figure 2 , the horizontal axis is the time value, and the vertical axis is the variable value. Curve 1 represents the wind speed curve, curve 2 represents the given speed curve, and curve 3 represents the actual speed curve. Figure 2 As indicated by the t1, t2, and t3 moments in , when the wind speed increases, the given speed decreases, and when the wind speed decreases, the given speed increases, that is, the given speed does not match the changing trend of the wind speed. The result is shown in Curve 3, and the actual speed also fluctuates. However, this situation cannot be solved by adjusting the parameters of the PI controller. The reason is that since the pitch speed is based on the speed of the wind turbine, and the speed of the wind turbine must lag behind the change of wind speed, changing the parameter value of the PI controller can only speed up the system response speed, and cannot solve the problem of pitch lag. On the other hand, the characteristic of the PI controller is that if the parameters are increased, although the system response speed may be accelerated, it is easy to cause system overshoot, which is not conducive to the stability of the wind turbine speed.

[0030] Through the above analysis of the characteristics of the existing PI controller and the following analysis of the characteristics of the PID controller, a pitch control method and a pitch control device according to an embodiment of the present disclosure are proposed, in which a "speed-speed PID" control method is adopted. Specifically, the speed-speed PID control method takes the given speed (i.e., the target speed) of the wind turbine as input, takes the actual speed of the wind turbine as feedback, and outputs a correction speed (i.e., the given pitch speed of the pitch motor) so that the actual pitch speed of the pitch motor accurately runs at the given pitch speed, thereby compensating for the untimeliness of the "pitch angle-pitch speed PID" control method and the actual speed execution deviation in the current pitch system control process.

[0031] Taking the incremental PID controller as an example, the differential term can predict the trend of error change. The proportional differential controller can make the control effect of suppressing the error equal to zero or even negative in advance, thereby avoiding serious overshoot of the controlled quantity. Therefore, for controlled objects with large inertia or lag, the proportional differential (PD) controller can improve the dynamic characteristics of the controlled object during the adjustment process, making the system response speed faster, overshoot smaller, oscillation lighter, and realizing the "prediction" effect of the dynamic process. The calculation formula of the incremental PID controller is shown in the following equation (1).

[0032] u(k)=Kp(e(k)-e(k-1))+Ki(e(k)+Kd(e(k)-2e(k-1)+e(k-2)) (1)

[0033] In equation (1), e(k) represents the current deviation (i.e., the difference between the actual speed of the wind turbine generator set at the kth moment and the given speed (i.e., the target speed), or the difference between the actual wind speed of the wind turbine generator set at the kth moment and the rated wind speed), e(k-1) is the previous deviation (i.e., the difference between the actual speed of the wind turbine generator set at the k-1th moment and the given speed (i.e., the target speed), or the difference between the actual wind speed of the wind turbine generator set at the k-1th moment and the rated wind speed), e(k-2) represents the previous previous deviation (i.e., the difference between the actual speed of the wind turbine generator set at the k-2th moment and the given speed (i.e., the target speed), or the difference between the actual wind speed of the wind turbine generator set at the k-2th moment and the rated wind speed), u(k) represents the speed value output by the PID controller this time (i.e., the given pitch speed of the pitch motor at the kth moment), and Kp, Ki and Kd represent the proportional coefficient, the integral coefficient and the differential coefficient, respectively.

[0034] Figure 3 1 is a flow chart showing a pitch control method according to an embodiment of the present disclosure. The pitch control method according to an embodiment of the present disclosure can be executed by a pitch control device (e.g., a pitch controller) of a wind turbine generator set, and the pitch control device can use a PID (proportional integral differential) controller to control the pitch motor.

[0035] Reference Figure 3 In step S301, the target speed and the actual speed of the wind turbine generator set are obtained, and the speed difference between the target speed and the actual speed of the wind turbine generator set is calculated. The target speed of the wind turbine generator set can be sent from the main controller of the wind turbine generator set to the pitch control device, and the actual speed of the wind turbine generator set can be collected by the speed sensor.

[0036] Next, in step S302, the first pitch control variable of the wind turbine generator set can be calculated based on the speed difference. Specifically, the first pitch control variable may include a proportional term and an integral term of the PID controller. The proportional term refers to Kp(e(k)-e(k-1)) shown in equation (1), and the integral term refers to Ki(e(k)+Kd(e(k)-2e(k-1)) shown in equation (1). Therefore, in order to calculate the proportional term and the integral term of the PID controller, the speed difference at least includes the speed difference at the current moment (e.g., e(k)) and the speed difference at the first moment (e.g., e(k-1)). Here, the first moment may represent the moment before the current moment. In this case, the first difference between the speed difference at the current moment and the speed difference at the previous moment may be first calculated, and then the product of the first difference and the proportional coefficient may be determined as the proportional term of the PID controller. On the other hand, the product of the speed difference at the current moment and the integral coefficient may be determined as the integral term of the PID controller.

[0037] Then, in step S303, the rated wind speed and the actual wind speed of the wind turbine generator set are obtained, and the wind speed difference between the rated wind speed and the actual wind speed of the wind turbine generator set is calculated. The rated wind speed of the wind turbine generator set can be preset and can be sent from the main controller of the wind turbine generator set to the pitch control device, and the actual wind speed of the wind turbine generator set can be obtained by any wind speed collection device (such as but not limited to an anemometer).

[0038] Next, in step S304, the second pitch control variable of the wind turbine generator set can be calculated based on the wind speed difference. Specifically, the second pitch control variable may include a differential term of the PID controller. The differential term refers to Kd(e(k)-2e(k-1)+e(k-2)) shown in equation (1). Therefore, in order to calculate the differential term of the PID controller, the wind speed difference includes at least the speed difference at the current moment (e.g., e(k)), the speed difference at the first moment (e.g., e(k-1)), and the speed difference at the second moment (e.g., e(k-2)). Here, the first moment may represent the moment before the current moment, and the second moment may represent the moment before the first moment. In this case, the second difference between the speed difference at the current moment and twice the speed difference at the first moment may be calculated first, and then the sum of the second difference and the speed difference at the second moment may be calculated, and finally the product of the sum and the differential coefficient is determined as the differential term of the PID controller.

[0039] Finally, in step S305, the operation of the pitch motor of the wind turbine generator set can be controlled according to the first pitch control variable and the second pitch control variable. Specifically, the output value of the PID controller, that is, the given pitch speed of the pitch motor, can be calculated according to the first pitch control variable and the second pitch control variable. The output value of the PID controller can be as shown in equation (1), that is, u(k)=Kp(e(k)-e(k-1))+Ki(e(k)+Kd(e(k)-2e(k-1)+e(k-2)). Optionally, the output value of the PID controller can be limited to prevent the given pitch speed of the pitch motor from being too large and causing the pitch motor to run too fast. For example, when the given pitch speed of the pitch motor is greater than the threshold speed (for example, when not limited to ±6 degrees / second), the given pitch speed of the pitch motor can be limited to the threshold speed. After the output value of the PID controller is limited, the output value after the limiting process can be used to control the operation of the pitch motor of the wind turbine. For example, the given pitch speed after the limiting process can be sent to the pitch drive to drive the pitch motor to run at the given pitch speed after the limiting process.

[0040] Optionally, as described above, the pitch control method according to an embodiment of the present disclosure may be operated in a constant power region. To this end, the pitch control method according to an embodiment of the present disclosure may further include the following steps: determining whether the actual rotational speed of the wind turbine generator set reaches the rated rotational speed, and when it is determined that the actual rotational speed of the wind turbine generator set reaches the rated rotational speed, that is, the wind turbine generator set has been operating in the constant power region, executing step S301.

[0041] Optionally, before controlling the operation of the pitch motor of the wind turbine generator set according to the first pitch control variable and the second pitch control variable, the measurement accuracy of the wind speed acquisition device and the rotation speed sensor may be verified. For example, the measured wind speed and rotation speed may be compared with a standard power curve to determine whether the wind speed, rotation speed, and power are within a normal range, thereby verifying the measurement accuracy of the wind speed acquisition device and the rotation speed sensor.

[0042] According to the pitch control method of the embodiment of the present disclosure, the pitch control of the wind turbine is realized by considering the dual effects of the rotational speed and the wind speed and utilizing the feedforward function of the differential, so that the pitch control can match the wind speed change, thereby maintaining the stability of the rotational speed of the wind turbine and effectively avoiding the problem of pitch angle overshoot. On the other hand, since the pitch control method according to the embodiment of the present disclosure is executed only when the rotational speed of the wind turbine reaches the rated speed, the fluctuation of the electromagnetic torque of the generator in the constant power region can be reduced. At the same time, since the pitch control method according to the embodiment of the present disclosure realizes the stable control of the rotational speed of the wind turbine, the vibration of the wind turbine can be reduced.

[0043] Figure 4 is a diagram illustrating an application example of the pitch control method according to an embodiment of the present disclosure.

[0044] Reference Figure 4 , the pitch control device of the wind turbine generator set can obtain the target speed 407 and the actual speed 406 of the wind turbine generator set, and then calculate the speed difference between the target speed 407 and the actual speed 406 through the difference calculation module (e.g., subtractor) 401. Subsequently, the speed difference can be input into the PID operation module 402 to calculate the first pitch control variable, that is, the proportional term and the integral term of the PID controller. On the other hand, the pitch control device of the wind turbine generator set can obtain the rated wind speed 408 of the wind turbine generator set 405, and can obtain the actual wind speed 409 of the wind turbine generator set 405 from the wind speed acquisition device 410, and then calculate the wind speed difference between the rated wind speed 408 and the actual wind speed 409 through the difference calculation module (e.g., subtractor) 411. Subsequently, the wind speed difference can also be input into the PID operation module 402 to calculate the second pitch control variable, that is, the differential term of the PID controller.

[0045] The PID operation module 402 can calculate the given pitch speed of the pitch motor 405 according to the first pitch control variable and the second pitch control variable, and the given pitch speed output by the PID operation module 402 can be limited by the limiting module 403. The output module (e.g., the pitch driver) 404 can drive the pitch motor 405 to operate based on the given pitch speed that has been limited. As described above, by limiting the given pitch speed output by the PID operation module 402 through the limiting module 403, it is possible to prevent the given pitch speed from being too large and causing the pitch motor to run too fast. For example, when the given pitch speed is greater than the threshold speed (e.g., when it is not limited to ±6 degrees / second), the given pitch speed can be limited to the threshold speed.

[0046] In the first case, if the actual rotational speed 406 is greater than the target rotational speed 407, and the actual wind speed 409 is greater than the rated wind speed 408, then based on equation (1), the given pitch speed output by the PID operation module 402 will decrease; in the second case, if the actual rotational speed 406 is less than the target rotational speed 407, and the actual wind speed 409 is less than the rated wind speed 408, then based on equation (1), the given pitch speed output by the PID operation module 202 will increase. On the other hand, in the third case, if the actual rotational speed 406 is greater than the target rotational speed 407, and the actual wind speed 409 is less than the rated wind speed 408, then based on equation (1), the given pitch speed output by the PID operation module 202 will be appropriately reduced (i.e., the degree of reduction in the given pitch speed will be less than the degree of reduction in the given pitch speed in the first case); in the fourth case, if the actual rotational speed 406 is less than the target rotational speed 407, and the actual wind speed 409 is greater than the rated wind speed 408, then based on equation (1), the given pitch speed output by the PID operation module 202 will be appropriately increased (i.e., the degree of increase in the given pitch speed will be less than the degree of increase in the given pitch speed in the second case).

[0047] The existing PID controller outputs the pitch control instruction according to the difference between the target speed and the actual speed of the wind turbine, so it is always "change first, then adjust"; and the pitch control method according to the embodiment of the present disclosure, because the differential feedforward is added, and the differential feedforward value depends on the wind speed but not on the speed value, it has the effect of predicting the wind speed change, so that the pitch adjustment law of the wind turbine is closer to the wind speed change law, thereby achieving more accurate speed control. On the other hand, according to the pitch control method of the embodiment of the present disclosure, when the wind speed increases, the given boundary speed follows the change of the wind speed, that is, when the wind speed force acts on the blade, the blade has already changed the pitch in advance, so that the force on the blade of the wind turbine can be stabilized, and the speed control of the wind turbine can be more stable.

[0048] Figure 5is a block diagram showing a pitch control device 500 of a wind turbine generator set according to an embodiment of the present disclosure. The pitch control device may use a PID (proportional integral derivative) controller to control a pitch motor.

[0049] The pitch control device 500 may include a processor 510 and a memory 520. The processor 510 may include (but not limited to) a central processing unit (CPU), a digital signal processor (DSP), a microcomputer, a field programmable gate array (FPGA), a system on a chip (SoC), a microprocessor, an application-specific integrated circuit (ASIC), etc. The memory 520 stores a computer program to be executed by the processor 510. The memory 520 includes a high-speed random access memory and / or a non-volatile computer-readable storage medium. When the processor 510 executes the computer program stored in the memory 520, the pitch control method as described above can be implemented.

[0050] Figure 6 is a simulation schematic diagram showing a pitch control method according to an embodiment of the present disclosure.

[0051] Reference Figure 6 , curve 601 indicates the wind speed, curve 602 indicates the original given pitch speed, and curve 603 indicates the given pitch speed calculated by the pitch control method according to the embodiment of the present disclosure. Figure 6 It can be seen that there is a trend change deviation between curve 602 and curve 601, while the change trend of curve 603 is basically consistent with the change trend of curve 601, and curve 603 and curve 601 are also matched with each other in timing. In addition, the amplitude of curve 603 and curve 601 are basically equal, and the change trend is the same (that is, when the wind speed decreases, the pitch direction is the pitch opening direction, and when the wind speed increases, the pitch direction is the pitch retracting direction), so it will not cause problems such as wind turbine speed overshoot and too fast pitch change.

[0052] like Figure 6As shown, in the traditional PI control, oscillation or even instability may occur in the adjustment process of overcoming the error. The reason is that there are large inertia components (links) or lag components in the control system, which have the effect of suppressing the error. Therefore, the change of the output of the control system always lags behind the change of the error. On the other hand, the differential control can reflect the rate of change of the error signal and foresee the trend of the error change, so it can produce an advanced control effect, that is, the error has been eliminated by the differential regulation before it is formed. Therefore, the pitch control method according to the embodiment of the present disclosure can improve the dynamic performance of the control system by introducing the differential term. The feedforward function of the differential is not based on feedback regulation, but works according to the principle of disturbance compensation, that is, when the disturbance occurs, the regulation signal can be issued, so as to overcome the adverse effects that may be caused by the disturbance in time and improve the regulation quality. Since the direct force of the speed of the wind turbine generator set is the wind speed, the pitch control method according to the embodiment of the present disclosure regards the wind speed deviation as a disturbance, and adds the regulation amount (that is, the differential term) directly fed back to the disturbance effect in the pitch controller, thereby improving the effect of the pitch control.

[0053] The pitch control method according to an embodiment of the present disclosure may be written as a computer program and stored on a computer-readable storage medium. When the computer program is executed by a processor, the pitch control method as described above may be implemented. Examples of computer-readable storage media include: read-only memory (ROM), random access programmable read-only memory (PROM), electrically erasable programmable read-only memory (EEPROM), random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), flash memory, nonvolatile memory, CD-ROM, CD-R, CD+R, CD-RW, CD+RW, DVD-ROM, DVD-R, DVD+R, DVD-RW, DVD+RW, DVD-RAM, BD-ROM, BD-R, BD-R LTH, BD-RE, Blu-ray or optical disk storage, hard disk drive (HDD), solid state drive (SSD), card storage (such as, multimedia card, secure digital (SD) card or extreme digital (XD) card), magnetic tape, floppy disk, magneto-optical data storage device, optical data storage device, hard disk, solid state disk and any other device, any other device is configured to store computer program and any associated data, data files and data structures in a non-transitory manner and provide the computer program and any associated data, data files and data structures to a processor or computer so that the processor or computer can execute the computer program. In one example, the computer program and any associated data, data files and data structures are distributed on a networked computer system so that the computer program and any associated data, data files and data structures are stored, accessed and executed in a distributed manner by one or more processors or computers.

[0054] According to the pitch control method, pitch control device and wind turbine generator set of the embodiment of the present disclosure, the pitch control of the wind turbine generator set is realized by considering the dual effects of the rotational speed and the wind speed and utilizing the feedforward function of the differential, so that the pitch control can match the wind speed change, thereby maintaining the stability of the rotational speed of the wind turbine generator set and effectively avoiding the problem of pitch angle overshoot. On the other hand, since the pitch control method according to the embodiment of the present disclosure is executed only when the rotational speed of the wind turbine generator set reaches the rated rotational speed, the fluctuation of the electromagnetic torque of the generator in the constant power region can be reduced. At the same time, since the pitch control method and pitch control device according to the embodiment of the present disclosure realize the stable control of the rotational speed of the wind turbine generator set, the vibration of the wind turbine generator set can be reduced.

[0055] In addition, according to the variable pitch control method of the embodiment of the present disclosure, since a differential feedforward is added, and the differential feedforward value depends on the wind speed but not on the speed value, it has the effect of predicting the change in wind speed, so that the pitch adjustment law of the wind turbine is closer to the wind speed change law, thereby achieving more accurate speed control. On the other hand, since only the differential feedforward is added without changing the parameters of the existing PI control, the variable pitch control method according to the embodiment of the present disclosure will not have a reverse effect on the speed regulation of the wind turbine. In addition, since the differential feedforward is added, when the wind speed suddenly increases, the pitch angle can be adjusted to retract the blades in time to prevent the wind turbine from overspeeding; when the wind speed suddenly decreases, the pitch angle can be adjusted to open the blades in time to prevent the power generation from decreasing due to the speed decreasing too low.

[0056] The pitch control method according to the embodiment of the present disclosure is simple and easy to implement, and does not require the wind speed of the wind turbine to be predicted. Instead, the prediction function of the differential is used to realize the pitch control in advance, thereby controlling the speed of the wind turbine to be stable and increasing the power generation. At the same time, since the change trend of the pitch speed can be close to the change trend of the wind speed, the load and vibration of the wind turbine can be reduced, and the mechanical loss of the wind turbine can be reduced, thereby extending the service life of the unit.

[0057] Although some embodiments of the present disclosure have been shown and described, it will be appreciated by those skilled in the art that modifications may be made to the embodiments without departing from the principles and spirit of the present disclosure, the scope of which is defined by the claims and their equivalents.

Claims

1. A pitch control method, characterized in that: The pitch control method comprises: Obtaining a target speed and an actual speed of the wind turbine generator set, and calculating a speed difference between the target speed and the actual speed of the wind turbine generator set; Calculating a first pitch control variable of the wind turbine generator set based on the rotational speed difference; Obtaining the rated wind speed and the actual wind speed of the wind turbine generator set, and calculating the wind speed difference between the rated wind speed and the actual wind speed of the wind turbine generator set; Calculating a second pitch control variable of the wind turbine generator set based on the wind speed difference; The operation of the pitch motor of the wind turbine generator set is controlled according to the first pitch control variable and the second pitch control variable.

2. The pitch control method according to claim 1, characterized in that: The first pitch control variable includes a proportional term and an integral term.

3. The pitch control method according to claim 2, characterized in that: The rotation speed difference includes a rotation speed difference at a current moment and a rotation speed difference at a first moment, wherein the first moment indicates a moment before the current moment.

4. The pitch control method according to claim 3, characterized in that: The proportional term is calculated as follows: Calculate a first difference between the speed difference at the current moment and the speed difference at the previous moment; The product of the first difference and the proportionality coefficient is determined as the proportional term.

5. The pitch control method according to claim 3, characterized in that: The integral term is calculated in the following manner: the product of the rotation speed difference at the current moment and the integral coefficient is determined as the integral term.

6. The pitch control method according to claim 1, characterized in that: The second pitch control variable includes a derivative term.

7. The pitch control method according to claim 6, characterized in that: The wind speed difference includes a wind speed difference at a current moment, a wind speed difference at a first moment, and a wind speed difference at a second moment, wherein the first moment represents a moment before the current moment, and the second moment represents a moment before the first moment.

8. The pitch control method according to claim 7, characterized in that: The differential term is calculated as follows: Calculate a second difference between the wind speed difference at the current moment and twice the wind speed difference at the first moment; Calculate the sum of the second difference and the wind speed difference at the second moment; The product of the sum and the differential coefficient is determined as the differential term.

9. The pitch control method according to claim 1, characterized in that: The step of controlling the operation of the pitch motor of the wind turbine generator set according to the first pitch control variable and the second pitch control variable comprises: Calculating an output value according to the first pitch control variable and the second pitch control variable; Performing a limiting process on the output value; The output value after amplitude limiting is used to control the operation of the pitch motor of the wind turbine generator set.

10. The pitch control method according to claim 1, characterized in that: The pitch control method further includes: Determine whether the actual speed of the wind turbine generator reaches the rated speed; In response to determining that the actual rotation speed of the wind turbine generator set reaches the rated rotation speed, the steps of acquiring the target rotation speed and the actual rotation speed of the wind turbine generator set and calculating the rotation speed difference between the target rotation speed and the actual rotation speed of the wind turbine generator set are performed.

11. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the pitch control method according to any one of claims 1 to 10 is implemented.

12. A pitch control device, characterized in that: The pitch controller device comprises: Processor; and A memory storing a computer program, which, when executed by a processor, implements the pitch control method according to any one of claims 1 to 10.

13. A wind turbine generator set, characterized in that: The wind turbine generator set comprises the pitch control device according to claim 12.

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