A method and system for overspeed prevention control of wind turbines based on auxiliary pitch algorithm

Abstract

The present invention discloses a method and system for preventing overspeed control of a wind turbine generator set based on an auxiliary pitch algorithm, the method comprising: obtaining the generator speed, speed change rate and auxiliary pitch angle of the previous operation cycle at the current moment of the current operation cycle; judging the gradient of the generator speed and speed change rate, and outputting the change rate of the auxiliary pitch angle corresponding to the gradient; obtaining the auxiliary pitch angle at the current moment according to the change rate of the auxiliary pitch angle of the previous operation cycle and the auxiliary pitch angle of the current operation cycle, and limiting the auxiliary pitch angle at the current moment; adding the limited auxiliary pitch angle to the pitch angle output by the main control system PID to obtain a given value of the pitch system, and the pitch system maintains the given value in the current operation cycle until entering the next operation cycle. When the wind speed surges, the present invention can avoid the shutdown caused by overspeed of the wind turbine generator set, reduce the limit load during overspeed shutdown, and ensure the smooth operation of the wind turbine generator set.

Description

Technical Field

[0001] The present invention relates to a method and system for preventing overspeed control of a wind turbine generator set based on an auxiliary pitch-changing algorithm, and belongs to the technical field of wind power generation control. Background Art

[0002] The main control system of a wind turbine generator set may include torque control and pitch control. When the wind turbine operates above the rated wind speed, it primarily controls the pitch angle to maintain a stable generator speed, thereby ensuring smooth operation and stable output power. However, in certain complex terrains, due to factors such as surface roughness, turbulence is high and wind speed fluctuates dramatically. In extreme cases, the wind speed variation rate can reach 4 m / s. Under such wind conditions, torque control has limited effect on suppressing generator speed, and pitch control is mainly used to achieve this. In addition, considering the hysteresis of the traditional control algorithm of the main control system and the significant inertia of the pitch angle execution system, the generator speed may exceed the control system's safety protection value, triggering an overspeed shutdown of the wind turbine. In such situations, the occurrence of damaging loads increases significantly. The existing pitch control method cannot effectively meet the requirements of load reduction and smooth shutdown control. Therefore, it is necessary to optimize the pitch control method. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a wind turbine overspeed prevention control method and system based on an auxiliary pitch control algorithm, which can avoid the shutdown of the wind turbine due to overspeed, effectively reduce the extreme load during overspeed shutdown, and ensure the smooth operation of the wind turbine. To achieve the above purpose, the present invention adopts the following technical solutions:

[0004] The present invention provides a wind turbine overspeed prevention control method based on an auxiliary pitch control algorithm, comprising:

[0005] Obtain the generator speed, speed change rate at the current moment of the current operating cycle and the auxiliary pitch angle of the previous operating cycle;

[0006] Determine the gradient to which the generator speed and the speed change rate belong, and output the rate of change of the auxiliary pitch angle corresponding to the gradient; the gradient includes a stable gradient, a first gradient, a second gradient, and a coincidence gradient, the rate of change of the auxiliary pitch angle corresponding to the stable gradient is to reduce the auxiliary pitch angle according to a third rate, the rate of change of the auxiliary pitch angle corresponding to the first gradient is to increase the auxiliary pitch angle according to a first rate, the rate of change of the auxiliary pitch angle corresponding to the second gradient is to increase the auxiliary pitch angle according to the second rate, and the rate of change of the auxiliary pitch angle corresponding to the coincidence gradient is to increase the auxiliary pitch angle according to the first rate;

[0007] The auxiliary pitch angle at the current moment is obtained according to the change rate of the auxiliary pitch angle in the previous operation cycle and the auxiliary pitch angle in the current operation cycle, and the auxiliary pitch angle at the current moment is limited to obtain the limited auxiliary pitch angle;

[0008] The limited auxiliary pitch angle is added to the main control system PID output pitch angle to obtain the pitch system set value. The pitch system maintains the set value in the current operation cycle until entering the next operation cycle.

[0009] Furthermore, the first gradient is when the generator speed exceeds a first threshold value A and the speed change rate exceeds a first reference value a, and the first threshold value A is lower than the rated speed of the generator.

[0010] Furthermore, the second gradient is when the generator speed exceeds a second threshold value B and the speed change rate exceeds a second reference value b, and the second threshold value B is higher than the rated speed of the generator.

[0011] Furthermore, the first reference value a is greater than the second reference value b.

[0012] Furthermore, the determination of the gradient of the generator speed and speed change rate includes:

[0013] Determine whether the generator speed and speed change rate meet the first gradient:

[0014] If the first gradient is satisfied, determine whether the second gradient is satisfied. If the second gradient is satisfied, the gradient is a coincidence gradient. If the second gradient is not satisfied, the gradient is a first gradient.

[0015] If the first gradient is not satisfied, it is determined whether the second gradient is satisfied. If the second gradient is satisfied, the gradient is the second gradient. If the second gradient is not satisfied, the gradient is the stable gradient.

[0016] Furthermore, the operation cycle is a PLC scanning cycle of the main control system, which is 10 to 20 ms, and the speed change rate is a speed change value of the generator per second.

[0017] Furthermore, the current auxiliary pitch angle is limited, wherein the limit value is: the minimum value is 0, and the maximum value is set according to the pitch angle of the local high wind speed wind turbine when it is running stably.

[0018] Furthermore, the first rate and the second rate are both greater than the third rate, and the auxiliary pitch angle increases quickly and decreases slowly, so as to ensure stable operation of the wind turbine.

[0019] Furthermore, the pitch system given value is a static variable with an initialization value of 0, and the next operation cycle retains the value at the end of the previous operation cycle. The initialization value is initialized only once during compilation.

[0020] Furthermore, if the auxiliary pitch angle decreases according to the third rate and decreases to 0, there is no risk of overspeed of the generator, the auxiliary pitch angle does not participate in the control, and the pitch angle is adjusted by the main control system PID.

[0021] Compared with the prior art, the wind turbine overspeed prevention control method and system based on the auxiliary pitch algorithm provided by the embodiments of the present invention have the following beneficial effects:

[0022] The present invention obtains the generator speed, speed change rate and auxiliary pitch angle at the current moment of the current operating cycle; judges the gradient of the generator speed and the speed change rate, and outputs the change rate of the auxiliary pitch angle corresponding to the gradient; the present invention continuously monitors the generator speed and the speed change rate, judges the gradient, determines the change rate of the auxiliary pitch angle, and realizes early control of the pitch angle action, which can effectively avoid the shutdown caused by overspeed of the wind turbine generator set, and effectively reduces the ultimate load during the overspeed shutdown, thereby ensuring the smooth operation of the wind turbine generator set.

[0023] The present invention sets four gradients: stable gradient, first gradient, second gradient and coincident gradient. When the generator speed is below the rated value and the speed change rate is very high, the auxiliary pitch angle is increased in time to control the pitch angle action in advance; when the generator speed is above the rated value and the speed change rate may be slightly reduced, but there is still a risk of overspeed, the auxiliary pitch angle continues to be increased to prevent overspeed caused by reducing the auxiliary pitch angle.

[0024] The present invention calculates the current auxiliary pitch angle based on the rate of change of the auxiliary pitch angle in the previous operating cycle and the current operating cycle. The current auxiliary pitch angle is then clipped to obtain the clipped auxiliary pitch angle. The clipped auxiliary pitch angle is then added to the main control system PID output pitch angle to obtain the pitch system setpoint. The pitch system maintains the setpoint during the current operating cycle until the next operating cycle begins. Generator speed changes are more sensitive than PID output changes. By adjusting the auxiliary pitch angle, the present invention can achieve the goal of advancing the pitch angle action and avoiding overspeed. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a flow chart of a wind turbine overspeed prevention control method based on an auxiliary pitch algorithm provided in Example 1 of the present invention;

[0026] Figure 2 Schematic diagram of four gradients in a wind turbine overspeed prevention control method based on an auxiliary pitch algorithm provided in Example 1 of the present invention;

[0027] Figure 3 This is a comparison diagram of the generator speed before and after the auxiliary pitch control algorithm is added to the wind turbine provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0029] Example 1:

[0030] like Figure 1 As shown, a wind turbine overspeed prevention control method based on an auxiliary pitch algorithm includes:

[0031] Obtain the generator speed, speed change rate at the current moment of the current operating cycle and the auxiliary pitch angle of the previous operating cycle;

[0032] Determine the gradient of the generator speed and speed change rate, and output the rate of change of the auxiliary pitch angle corresponding to the gradient;

[0033] The auxiliary pitch angle at the current moment is obtained according to the change rate of the auxiliary pitch angle in the previous operation cycle and the auxiliary pitch angle in the current operation cycle, and the auxiliary pitch angle at the current moment is limited to obtain the limited auxiliary pitch angle;

[0034] The limited auxiliary pitch angle is added to the main control system PID output pitch angle to obtain the pitch system set value. The pitch system maintains the set value in the current operation cycle until entering the next operation cycle.

[0035] The specific steps include:

[0036] Step 1: Obtain the generator speed, speed change rate at the current moment of the current operating cycle and the auxiliary pitch angle of the previous operating cycle.

[0037] The operation cycle is the PLC scanning cycle of the main control system, which is usually 10 to 20 ms. The speed change rate is the speed change value of the generator per second, which can effectively reduce the frequent malfunction of the blades caused by the pitch angle compensation value.

[0038] Step 2: Determine the gradient of the generator speed and speed change rate, and output the rate of change of the auxiliary pitch angle corresponding to the gradient.

[0039] like Figure 2 The gradients shown include a steady gradient, a first gradient, a second gradient, and a coincident gradient.

[0040] The first gradient is when the generator speed exceeds a first threshold A and the speed change rate exceeds a first reference value a, and the first threshold A is lower than the rated speed of the generator. The auxiliary pitch angle change rate corresponding to the first gradient is to increase the auxiliary pitch angle at a first rate.

[0041] The second gradient is when the generator speed exceeds a second threshold B and the speed change rate exceeds a second reference value b, and the second threshold B is higher than the rated speed of the generator. The auxiliary pitch angle change rate corresponding to the second gradient is to increase the auxiliary pitch angle at a second rate.

[0042] It should be noted that the first reference value a is greater than the second reference value b. Specifically, the first threshold value A is lower than the rated generator speed, and the second threshold value B is higher than the rated generator speed. Using these two gradients, when the generator speed is below the rated value and the speed change rate is high, the auxiliary pitch angle is promptly increased to preemptively control the pitch angle action. When the generator speed is above the rated value and the speed change rate may decrease slightly, but there is still a risk of overspeed, the auxiliary pitch angle is further increased to prevent overspeed caused by reducing the auxiliary pitch angle.

[0043] The rate of change of the auxiliary pitch angle corresponding to the stabilization gradient is to reduce the auxiliary pitch angle at a third rate.

[0044] The rate of change of the auxiliary pitch angle corresponding to the overlap gradient is to increase the auxiliary pitch angle at a first rate.

[0045] It should be noted that both the first and second rates are greater than the third rate. This rapid increase and slow decrease ensures stable turbine operation. This also avoids the need to pre-determine specific values ​​for additional pitch angle compensation for wind turbines, as precise pitch angle compensation values ​​are difficult to specify for different turbine models and operating conditions.

[0046] Determine the gradient of the generator speed and speed change rate, including:

[0047] Determine whether the generator speed and speed change rate meet the first gradient:

[0048] If the first gradient is satisfied, determine whether the second gradient is satisfied. If the second gradient is satisfied, the gradient is a coincidence gradient. If the second gradient is not satisfied, the gradient is a first gradient.

[0049] If the first gradient is not satisfied, it is determined whether the second gradient is satisfied. If the second gradient is satisfied, the gradient is the second gradient. If the second gradient is not satisfied, the gradient is the stable gradient.

[0050] The present invention continuously monitors the generator speed and speed change rate, and compares them with a predetermined gradient to determine whether the auxiliary pitch angle needs to be increased or decreased. The pitch angle action is controlled in advance when necessary, which can effectively avoid shutdown caused by overspeed of the wind turbine set, and effectively reduce the ultimate load during overspeed shutdown, thereby ensuring the smooth operation of the wind turbine set.

[0051] Step 3: According to the auxiliary pitch angle in the previous operation cycle and the rate of change of the auxiliary pitch angle in the current operation cycle, the auxiliary pitch angle at the current moment is obtained, and the auxiliary pitch angle at the current moment is limited to obtain the limited auxiliary pitch angle.

[0052] The limits are: the minimum value is 0, and the maximum value is set according to the pitch angle of the local high wind speed wind turbine when it is running stably.

[0053] Step 4: Add the limited auxiliary pitch angle to the main control system PID output pitch angle to obtain the pitch system set value. The pitch system maintains the set value in the current operation cycle until entering the next operation cycle.

[0054] The change of generator speed is more sensitive than the change of PID output. The present invention can achieve the purpose of advancing the pitch angle action by adjusting the auxiliary pitch angle to avoid overspeed.

[0055] The auxiliary pitch angle is a static variable with an initialization value of 0. The next operation cycle retains the value at the end of the previous operation cycle. The initialization value is initialized only once during compilation.

[0056] If the auxiliary pitch angle decreases according to the third rate and decreases to 0, there is no risk of overspeed of the generator, the auxiliary pitch angle does not participate in the control, and the pitch angle is adjusted by the main control system PID.

[0057] The present invention can effectively avoid shutdown of the wind turbine generator set caused by overspeed, effectively reduce the limit load during shutdown due to overspeed, and ensure the stable operation of the wind turbine generator set.

[0058] Example 2:

[0059] This embodiment adopts the wind turbine overspeed prevention control method based on the auxiliary pitch algorithm described in Example 1 to perform overspeed prevention control in a certain wind farm.

[0060] During normal operation of the wind turbine, the generator speed and speed change rate are monitored in real time during each operating cycle. If the generator speed exceeds 1600 rpm and the speed increase rate exceeds 20 rps, the generator speed will surge, and the auxiliary pitch angle will increase by 0.14° per cycle. If the generator speed surges again, and if the generator speed exceeds 1860 rpm and the speed increase rate exceeds 5 rps, there is a risk of overspeed at the next moment, and the auxiliary pitch angle will increase by 0.05° per cycle. If the generator speed does not exceed 1860 rpm and the speed increase rate exceeds 5 rps, there is no risk of overspeed at the next moment, and the auxiliary pitch angle will decrease by 0.02° per cycle.

[0061] The obtained auxiliary pitch angle is limited in the range of 0-15°. The limited auxiliary pitch angle is added to the PID output of the main control system to obtain the pitch angle set value of the variable pitch system, which realizes the advance control of the pitch angle action, effectively avoiding the shutdown caused by overspeed of the wind turbine, thereby reducing the ultimate load.

[0062] like Figure 3As shown in the figure, the thick solid line is the generator speed curve before the auxiliary pitch algorithm is added, and the unit is shut down due to overspeed; the thick dashed line is the generator speed curve after the auxiliary pitch algorithm is added, and the unit is overspeeding and running smoothly; the thin dashed line is the wind speed data collected in real time on site. Figure 3 It can be seen that after adopting the wind turbine overspeed prevention control method based on the auxiliary pitch algorithm described in Example 1, the turbine runs smoothly and the overspeed of the turbine is effectively controlled under extreme wind conditions.

[0063] The wind turbine overspeed prevention control method based on the auxiliary pitch algorithm described in Example 1 has been widely used in a certain wind farm. It can avoid shutdown caused by overspeed of wind turbines, reduce the extreme load during overspeed shutdown, and ensure the smooth operation of wind turbines.

[0064] The present invention enables wind turbines to operate smoothly in extreme external environments using an optimized pitch angle control method. Compared to existing pitch angle control methods, it can effectively avoid shutdowns caused by overspeed, thereby reducing the ultimate load and ensuring smooth operation of the wind turbine.

[0065] Example 3:

[0066] An embodiment of the present invention provides a wind turbine overspeed prevention control system based on an auxiliary pitch control algorithm, comprising:

[0067] Acquisition module: used to obtain the generator speed, speed change rate and auxiliary pitch angle at the current moment of the current operation cycle;

[0068] Auxiliary pitch angle adjustment module: used to determine the gradient of the generator speed and speed change rate, and output the change rate of the auxiliary pitch angle corresponding to the gradient;

[0069] Limiting module: used to limit the current auxiliary pitch angle to obtain the limited auxiliary pitch angle;

[0070] Output module: used to add the limited auxiliary pitch angle to the main control system PID output pitch angle to obtain the pitch system set value. The pitch system maintains the set value in the current operation cycle until entering the next operation cycle.

[0071] The acquisition module is connected to the wind turbine main control system for communication, and the output module is connected to the pitch control system for communication.

[0072] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0073] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0074] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0075] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0076] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A wind turbine overspeed prevention control method based on auxiliary pitch algorithm, characterized in that: include: Obtain the generator speed, speed change rate and auxiliary pitch angle of the previous operation cycle at the current moment of the current operation cycle; Determine the gradient to which the generator speed and the speed change rate belong, and output the change rate of the auxiliary pitch angle corresponding to the gradient; the gradient includes a stable gradient, a first gradient, a second gradient, and a coincidence gradient, the change rate of the auxiliary pitch angle corresponding to the stable gradient is to reduce the auxiliary pitch angle at a third rate, the change rate of the auxiliary pitch angle corresponding to the first gradient is to increase the auxiliary pitch angle at a first rate, the change rate of the auxiliary pitch angle corresponding to the second gradient is to increase the auxiliary pitch angle at a second rate, and the change rate of the auxiliary pitch angle corresponding to the coincidence gradient is to increase the auxiliary pitch angle at the first rate; The auxiliary pitch angle at the current moment is obtained according to the change rate of the auxiliary pitch angle in the previous operation cycle and the auxiliary pitch angle in the current operation cycle, and the auxiliary pitch angle at the current moment is limited to obtain the auxiliary pitch angle after the limitation; The limited auxiliary pitch angle is added to the main control system PID output pitch angle to obtain the pitch system set value. The pitch system maintains the set value in the current operation cycle until entering the next operation cycle.

2. The wind turbine overspeed prevention control method based on auxiliary pitch algorithm according to claim 1 is characterized in that: The first gradient is when the generator speed exceeds a first threshold value A and the speed change rate exceeds a first reference value a, and the first threshold value A is lower than the rated speed of the generator.

3. The wind turbine overspeed prevention control method based on auxiliary pitch algorithm according to claim 2 is characterized in that: The second gradient is when the generator speed exceeds a second threshold value B and the speed change rate exceeds a second reference value b, and the second threshold value B is higher than the rated speed of the generator.

4. The wind turbine overspeed prevention control method based on auxiliary pitch algorithm according to claim 3 is characterized in that: The first reference value a is greater than the second reference value b.

5. The wind turbine overspeed prevention control method based on auxiliary pitch algorithm according to claim 3 is characterized in that: The step of determining the gradient of the generator speed and the speed change rate includes: Determine whether the generator speed and speed change rate meet the first gradient: If the first gradient is satisfied, it is determined whether the second gradient is satisfied. If the second gradient is satisfied, the gradient is a coincidence gradient. If the second gradient is not satisfied, the gradient is the first gradient. If the first gradient is not satisfied, it is determined whether the second gradient is satisfied; if the second gradient is satisfied, the gradient is the second gradient; if the second gradient is not satisfied, the gradient is the stable gradient.

6. The wind turbine overspeed prevention control method based on auxiliary pitch algorithm according to claim 1 is characterized in that: The operation cycle is the PLC scanning cycle of the main control system, which is 10-20ms, and the speed change rate is the speed change value of the generator per second.

7. The wind turbine overspeed prevention control method based on auxiliary pitch algorithm according to claim 1 is characterized in that: The auxiliary pitch angle at the current moment is limited, wherein the limit value is: the minimum value is 0, and the maximum value is set according to the pitch angle when the local high wind speed wind turbine is running stably.

8. The wind turbine overspeed prevention control method based on auxiliary pitch algorithm according to claim 1 is characterized in that: The first rate and the second rate are both greater than the third rate, and the auxiliary pitch angle increases quickly and decreases slowly, so as to ensure stable operation of the wind turbine.

9. The wind turbine overspeed prevention control method based on auxiliary pitch algorithm according to claim 1 is characterized in that: The auxiliary pitch angle is a static variable with an initialization value of 0. The next operation cycle retains the value at the end of the previous operation cycle. The initialization value is initialized only once during compilation.

10. The wind turbine overspeed prevention control method based on auxiliary pitch algorithm according to claim 6, characterized in that: If the auxiliary pitch angle decreases at the third rate and decreases to 0, there is no risk of overspeeding of the generator, the auxiliary pitch angle does not participate in the control, and the pitch angle is adjusted by the main control system PID.

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