Variable pitch control method and system of wind generating set and wind generating set

Abstract

The invention provides a variable pitch control method and system of a wind generating set and the wind generating set, and the variable pitch control method comprises the steps that the change trend of the rotating speed of a generator of the wind generating set is determined in response to the situation that the current output power of the wind generating set reaches the rated power; and on the basis of control strategies corresponding to the change trends, blade variable pitch of the wind generating set is controlled, different change trends correspond to different control strategies, and the control strategies comprise the first control strategy and the second control strategy. The problem that a variable-pitch load reduction scheme in the related technology is difficult to be suitable for the large-megawatt wind generating set is solved, the unit can effectively reduce the load under the rated power, and the safety and stability of unit operation are ensured.

Description

Technical Field

[0001] The present disclosure relates to the field of wind power generation, and more specifically, to a variable pitch control method and system for a wind generator set and a wind generator set. Background Art

[0002] As an inexhaustible, clean and pollution-free renewable energy, the development and utilization of wind energy has received widespread attention in the energy field. With the development of wind power generation technology, the control mode of wind turbines has also undergone improvements such as fixed-pitch stall wind turbines, variable-pitch constant-speed wind turbines, and variable-speed constant-frequency wind turbines. Among them, compared with stall wind turbines, the biggest advantage of variable-speed constant-frequency wind turbines is that the output power is stable above the rated wind speed, and it has become the mainstream model today. With the increase in demand for wind power generation, large-megawatt wind turbines are becoming more and more widely used. The unit capacity of the unit has exceeded 16 megawatts, the blade length of the unit has continued to increase, and the tower height has exceeded 140 meters.

[0003] Specifically, compared with small-power units, large-megawatt wind turbines face more severe challenges in terms of unit safety and grid stability on the basis of increasing power generation. On the one hand, due to the larger blades and towers of large-megawatt units, the units are more sensitive to changes in wind conditions and the wind load has a more obvious impact on the loads of key components. For example, when the blade length increases, the swept area will be larger and more wind energy can be absorbed. Therefore, the blades are more sensitive to changes in wind speed, and the fatigue load (especially the blade root load) synthesized to the center of the hub will be greater. In addition, the impeller speed is more significantly affected by changes in wind speed, which will also increase fatigue loads. On the other hand, as the tower rises, the vibration amplitude of the top and bottom of the tower will be greater due to changes in wind speed, which will significantly increase the fatigue load of the tower and even seriously affect the life of the tower. On the other hand, the output power of large megawatt units is greater. Compared with small power units, at the same power fluctuation percentage, the maximum output power of large megawatt units will be greater. For example, for a unit with a rated power of 7500kw, the power fluctuation range of 15% is ±1125kw; while for a large megawatt unit of 16MW, the power fluctuation range is ±2400kw. Therefore, for large megawatt units, the impact on the unit converter end and even the grid side will be greater.

[0004] Large-megawatt wind turbines have greater demands on output power stability and fatigue load reduction of key components than small-power units. Therefore, compared with small-power units, the control strategy for output power and load reduction of key components also needs to consider more practical issues.

[0005] However, the variable pitch load reduction schemes in the related technologies are all designed for small-power units, and the particularities of large-megawatt units are not taken into account during the control process. Therefore, they are difficult to apply to large-megawatt units. Even if they are applied to large-megawatt units, it is difficult to ensure the safety and stability of the units. Summary of the invention

[0006] In view of the problem that the variable pitch load reduction scheme in the related art is difficult to apply to large megawatt wind turbines, the present disclosure provides a variable pitch control method and system for a wind turbine and a wind turbine.

[0007] A first aspect of the present disclosure provides a pitch control method for a wind turbine generator set, the pitch control method comprising: in response to the current output power of the wind turbine generator set reaching the rated power, determining the change trend of the generator speed of the wind turbine generator set; based on a control strategy corresponding to the change trend, controlling the blade pitch of the wind turbine generator set, wherein different change trends correspond to different control strategies, the control strategy comprising a first control strategy and a second control strategy, the first control strategy comprising: taking a preset power as a control target of the output power of the wind turbine generator set to control the blade pitch, and the second control strategy comprising: taking a preset torque as a control target of the torque of the generator of the wind turbine generator set to control the blade pitch.

[0008] Optionally, the blade pitch of the wind turbine generator set is controlled in the following manner: in response to the changing trend being an upward trend, the blade pitch is controlled based on the second control strategy; in response to the changing trend being a downward trend, the blade pitch is controlled based on the first control strategy.

[0009] Optionally, the pitch control method also includes: in response to the change in the variation trend, switching between the first control strategy and the second control strategy by adjusting a preset minimum torque coefficient, a maximum torque coefficient and a switching power coefficient, wherein the minimum torque coefficient and the maximum torque coefficient are used to determine a control target of the torque of the generator, and the switching power coefficient is used to determine a control target of the output power of the wind turbine generator set.

[0010] Optionally, switching to the first control strategy is performed by adjusting the minimum torque coefficient to be within a minimum coefficient range, adjusting the maximum torque coefficient to be within a maximum coefficient range, and adjusting the switching power coefficient to a preset power coefficient, wherein the minimum torque coefficient is less than the maximum torque coefficient.

[0011] Optionally, the second control strategy is executed in the following manner: the minimum torque coefficient and the maximum torque coefficient are both adjusted to preset torque coefficients, and the switching power coefficient is adjusted to be within a power coefficient range, wherein the lower limit value of the power coefficient range is greater than the preset power coefficient, and the preset torque coefficient is greater than or equal to the upper limit value of the minimum coefficient range, and is less than or equal to the lower limit value of the maximum coefficient range.

[0012] Optionally, the pitch control method also includes: in response to the current output power of the wind turbine being less than a preset power limit, executing the step of determining the changing trend of the generator speed of the wind turbine; in response to the current output power of the wind turbine being greater than or equal to the power limit, controlling the blades to pitch based on the first control strategy, wherein the power limit is determined based on the switching power coefficient and the rated power of the wind turbine.

[0013] Optionally, the changing trend of the generator speed of the wind turbine generator set is determined in the following manner: comparing the current measured generator speed with the preset generator speed to determine the speed difference; based on the speed difference, determining the speed difference change rate; comparing the speed difference and the speed difference change rate to determine the speed change rate; based on the speed change rate, determining the changing trend of the generator speed.

[0014] Optionally, the changing trend of the generator speed is determined in the following manner: in response to the speed change rate satisfying a preset condition, determining that the generator speed is in an upward trend; in response to the speed change rate not satisfying the preset condition, determining that the generator speed is in a downward trend, wherein the preset condition includes: the speed change rate exceeds a preset value, and the duration for which the speed change rate exceeds the preset value exceeds a preset duration.

[0015] Optionally, the wind turbine is a large megawatt wind turbine, the single-unit capacity of the wind turbine is greater than or equal to 6 megawatts, the blades of the wind turbine are long flexible blades, the length of the long flexible blades is greater than or equal to 85 meters, and the impeller diameter of the wind turbine is greater than or equal to 175 meters.

[0016] A second aspect of the present disclosure provides a control system for a wind turbine generator set, the control system comprising: at least one processor; at least one memory storing computer executable instructions, wherein the computer executable instructions, when executed by the at least one processor, prompt the at least one processor to execute the variable pitch control method of the wind turbine generator set as described in the embodiments of the present disclosure.

[0017] A third aspect of the present disclosure provides a wind turbine generator set, wherein the wind turbine generator set comprises the control system of the wind turbine generator set according to the embodiment of the present disclosure.

[0018] A fourth aspect of the present disclosure provides a computer-readable storage medium. When instructions in the computer-readable storage medium are executed by a processor of an electronic device, the electronic device is enabled to execute the pitch control method of a wind turbine generator set according to an embodiment of the present disclosure.

[0019] A fifth aspect of the present disclosure provides a computer program product, which includes computer executable instructions, and when the computer executable instructions are executed by at least one processor, the variable pitch control method of the wind turbine generator set according to the embodiment of the present disclosure is implemented.

[0020] According to the pitch control method, system and wind turbine generator set of the present invention, when the current output power of the wind turbine generator set reaches the rated power, different control strategies can be adopted for different changing trends according to the changing trend of the generator speed to control the pitch of the blades of the unit, wherein the control strategy can include a first control strategy that takes a preset power as the control target of the output power, and a second control strategy that takes a preset torque as the control target of the torque of the generator. In this way, different control strategies can be adopted under different generator speed conditions to avoid the problem of poor control effect of a single control strategy. By switching different control strategies, the unit can be effectively loaded down at rated power to ensure the safety and stability of the unit operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic flow chart showing a pitch control method of a wind turbine generator system according to an exemplary embodiment of the present disclosure.

[0022] Figure 2 1 is a timing diagram showing the output power of a wind turbine generator set under constant power control and constant torque control according to an exemplary embodiment of the present disclosure.

[0023] Figure 3 1 is a timing diagram showing the tower bottom load of a wind turbine generator set under constant power control and constant torque control according to an exemplary embodiment of the present disclosure.

[0024] Figure 4A is a schematic block diagram showing a pitch control method of a wind turbine generator system according to an exemplary embodiment of the present disclosure.

[0025] Figure 4B is a schematic diagram showing determination of a rotation speed change rate in a pitch control method of a wind turbine generator set according to an exemplary embodiment of the present disclosure.

[0026] Figure 5 2 is a schematic diagram showing the selection of optimal parameters for a wind turbine generator set in comparison with the timing of outputting active power of the wind turbine generator set according to an exemplary embodiment of the present disclosure.

[0027] Figure 6 is a schematic diagram showing the selection of optimal parameters of a wind turbine generator set in comparison with the timing of the tower bottom load of the wind turbine generator set according to an exemplary embodiment of the present disclosure.

[0028] Figure 7 2 is a schematic diagram showing the selection of the optimal power factor of a wind turbine generator set in comparison with the timing of outputting active power of the wind turbine generator set according to an exemplary embodiment of the present disclosure.

[0029] Figure 8 is a schematic diagram showing the selection of the optimal power coefficient of a wind turbine generator set in comparison with the timing sequence of the tower bottom load of the wind turbine generator set according to an exemplary embodiment of the present disclosure.

[0030] Fig.9A , Fig. 9B and Fig. 9C 1 is a timing diagram showing a comparative example of output active power using a pitch control method of a wind turbine generator set according to an exemplary embodiment of the present disclosure, a constant power control method, and a constant torque control method.

[0031] Fig. 10A , Fig. 10B and Fig. 10C 1 is a timing diagram showing a comparative example of tower bottom load using a pitch control method of a wind turbine generator set according to an exemplary embodiment of the present disclosure, a constant power control method, and a constant torque control method.

[0032] Fig.11 1 is a schematic diagram showing a comparative example of the fatigue load on the tower bottom using a pitch control method of a wind turbine generator set according to an exemplary embodiment of the present disclosure, a constant power control method, and a constant torque control method.

[0033] Fig. 12A , Fig. 12B , Fig. 12C and Fig.12D 1 is a timing diagram showing a comparative example of hub center load using a pitch control method of a wind turbine generator set according to an exemplary embodiment of the present disclosure, a constant power control method, and a constant torque control method.

[0034] Fig.13 1 is a schematic diagram showing a comparative example of fatigue loads on key components of a wind turbine generator set using a pitch control method according to an exemplary embodiment of the present disclosure, a constant power control method, and a constant torque control method. DETAILED DESCRIPTION

[0035] 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.

[0036] The features described herein can be implemented in different forms and should not be construed as being limited to the examples described herein. Rather, the examples described herein have been provided to illustrate only some of the many possible ways to implement the methods, devices, and / or systems described herein, which will be clear after understanding the disclosure of the present application.

[0037] As used herein, the term "and / or" includes any one of the associated listed items and any combination of any two or more.

[0038] Although terms such as "first", "second", and "third" may be used herein to describe various members, components, regions, layers, or portions, these members, components, regions, layers, or portions should not be limited by these terms. Instead, these terms are only used to distinguish one member, component, region, layer, or portion from another member, component, region, layer, or portion. Therefore, without departing from the teachings of the examples described herein, the first member, first component, first region, first layer, or first portion referred to in the examples may also be referred to as the second member, second component, second region, second layer, or second portion.

[0039] In the specification, when an element (such as a layer, a region, or a substrate) is described as being “on”, “connected to”, or “coupled to” another element, the element may be directly “on”, “connected to”, or “coupled to” another element, or one or more other elements may be present therebetween. Conversely, when an element is described as being “directly on”, “directly connected to”, or “directly coupled to” another element, there may be no other elements present therebetween.

[0040] The terms used herein are only used to describe various examples and are not intended to limit the disclosure. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms "comprise", "include" and "have" indicate the presence of the described features, quantities, operations, components, elements and / or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, operations, components, elements and / or combinations thereof.

[0041] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by a person of ordinary skill in the art to which the present disclosure belongs after understanding the present disclosure. Unless explicitly defined as such herein, terms (such as those defined in a general dictionary) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and the present disclosure, and should not be interpreted in an idealized or overly formal manner.

[0042] Furthermore, in the description of examples, when it is considered that a detailed description of a well-known related structure or function would cause vague interpretation of the present disclosure, such a detailed description will be omitted.

[0043] As mentioned above, the variable pitch load reduction schemes in the relevant technologies are all designed for small-power units. The particularities of large-megawatt units are not taken into account during the control process. Therefore, it is difficult to apply to large-megawatt units. Even if applied to large-megawatt units, it is difficult to ensure the safety and stability of the units.

[0044] Specifically, in large-megawatt wind turbines, the blades are longer, and the impeller diameter can reach 175m or even more than 200m. Because the blades are longer, their flexibility is more obvious, so long and flexible blades are usually used in large-megawatt wind turbines. Long and flexible blades are usually manufactured using a carbon-glass hybrid process. Long and flexible blades are more sensitive to wind speed. Under the same wind speed change, the load change of long and flexible blades is greater than that of short blades. Large loads will seriously affect the service life of the blades. In addition, the tower of a large-megawatt wind turbine is higher, reaching more than 170m. As the tower rises, the vibration of the tower, especially the vibration of the top of the tower, is larger, causing the tower load to increase significantly, which will also seriously affect the life of the high tower. Therefore, large-megawatt wind turbines need to pay more attention to the load problem during the operation of the unit than small-power units.

[0045] In addition, large-megawatt units have a larger installed capacity. Due to the large base, compared with the small-power units in the past, at the same power fluctuation percentage, the power fluctuation range of large-megawatt units is larger, the impact on the power grid is greater, and it will seriously affect the adaptability of the power grid.

[0046] Therefore, when large-megawatt wind turbines operate above the rated wind speed, it is necessary to ensure that the output power above the rated power point is stable and avoid fluctuations to improve grid friendliness; it is also necessary to keep the load on key components of the unit within a controllable range to reduce the fatigue load of the unit, which is conducive to extending the life of the unit.

[0047] However, in the relevant technology, variable speed constant frequency wind turbines mainly adopt variable pitch control technology, that is, when the wind speed is too high, the airflow to the blade power angle is changed by adjusting the pitch angle, thereby changing the aerodynamic torque obtained by the unit, so that the power output of the unit remains stable and the wind load is reduced. It has not fundamentally proposed how to reduce the load on the key components of the unit while ensuring the stability of the output power of large megawatt units.

[0048] In some control strategies, when the wind speed reaches the rated wind speed, the unit enters the full-power state. At this time, the pitch angle can be dynamically controlled to make the unit run stably at the rated speed, and the dynamic rated power output can be maintained according to the constant power or constant torque control method.

[0049] In the embodiments of the present disclosure, through simulation and measurement, when the output power reaches above the rated power, constant power control and constant torque control each have their advantages and disadvantages. For example, under constant power control, the output power of the unit is more stable; and under constant torque control, the load on the key components of the unit is smaller.

[0050] Specifically, when the on-site wind speed reaches the full wind speed designed for the wind turbine, theoretically, the speed and power are both in a stable state. The basic control strategy of a wind turbine can be: when the wind speed is below the rated wind speed, the speed of the unit is controlled by controlling the generator torque, so that the impeller speed is maintained at the optimal tip speed ratio, so that the unit can capture wind energy with maximum efficiency; when the wind speed is above the rated wind speed, the impeller speed is controlled by controlling the blade pitch angle to maintain the rated speed, and the unit outputs energy at a constant power. Due to the existence of the relationship T = Kopt × n 2 , where T is the torque of the generator; n is the current speed of the generator; Kopt is the optimal gain value of the wind turbine generator set. Assuming that the power output of the unit is stable, the speed of the generator is inversely proportional to the torque. Therefore, when the wind speed is above the rated wind speed, the unit is in full power state. At this time, constant power control or constant torque control can be used.

[0051] In constant power control, the rated power can be used as the control target, and the pitch angle can be adjusted through pitch proportional integral (PI) control. The torque T = P rated / ω m , where P rated is the output power, ω m is the real-time speed. In this control mode, the unit maintains a relatively constant output power at different speeds: at low speeds, the torque of the generator is large; at high speeds, in order to maintain constant power, the torque of the generator will decrease. Therefore, under this control mode, the unit's output active power is relatively stable and has small fluctuations, which is more friendly to the unit's converter end and the power grid. However, since the unit uses stable power as the control target, the torque fluctuation is large, which will increase the unit's fatigue load and shorten the unit's life.

[0052] Constant power control is usually applicable to loads that need to maintain constant power over a wide speed range, or in scenarios where grid connection requirements are more stringent and power fluctuations are not allowed to be too large to ensure grid safety.

[0053] In constant torque control, the rated speed can be used as the control target, and the pitch angle can be adjusted through pitch PI control. The torque T = P rated / ω r , where ω r is the rated speed. The output torque of the unit remains constant at different speeds: at low speeds, theoretically, the output power will decrease, and P = K × ω × T indicates that the generator torque will increase. The control goal of constant torque control is relatively stable torque, which means that regardless of the speed, the torque required by the generator load is the same, the torque fluctuation of the unit is small, the load is smaller, it is more friendly to the fatigue load of the unit, and it is beneficial to extend the life of the unit. Under constant torque control, the proportion of problems with key components of the unit is small. However, due to large power fluctuations, the power may be over-generated and exceed the rated power more. However, since the power grid has stricter requirements on the output power of the unit, most units use constant power control.

[0054] Since constant power control and constant torque control each have their own defects, they may not be able to meet the needs of large megawatt units to achieve safe load reduction while ensuring power stability.

[0055] In view of the above problems, the present disclosure provides a pitch control method of a wind turbine generator set, a pitch control system of a wind turbine generator set, a wind turbine generator set, a computer-readable storage medium and a computer program product to solve or at least alleviate the above problems.

[0056] According to a first aspect of an exemplary embodiment of the present disclosure, a pitch control method of a wind turbine is provided. The pitch control method can be executed by a computer device having computing capabilities, for example, by a computer device in a pitch control system of a wind turbine. The computer device executing the pitch control method can be, for example, a terminal device or a server, wherein the terminal device can be, for example, a tablet computer, a laptop computer, a digital assistant, etc.; the server can be an independent server, a server cluster, a cloud computing platform, or a virtualization center.

[0057] Here, the computer device may be arranged at a wind turbine generator set or a wind farm, for example, and may be communicatively connected to a measuring device or a data center of the wind turbine generator set or the wind farm, so as to obtain the data required for executing the above method.

[0058] In an embodiment according to the present disclosure, the pitch control method of a wind turbine generator set may be applied to a large megawatt wind turbine generator set.

[0059] Here, a large megawatt wind turbine generator set may differ from an ordinary unit in terms of single-unit capacity, impeller diameter (or blade length) and tower height. As an example, the single-unit capacity of the wind turbine generator set may be greater than or equal to 6 megawatts, the blades of the wind turbine generator set may be long-flexible blades, the length of the long-flexible blades may be greater than or equal to 85 meters, and the impeller diameter of the wind turbine generator set may be greater than or equal to 175 meters.

[0060] In large-megawatt wind turbines, long flexible blades can be used. The length of the long flexible blades can even be more than 100 meters. A mixed material of carbon fiber and glass fiber can be used. Compared with traditional short blades, long flexible blades are more flexible, have less damping, and are more sensitive to wind loads. Even a small change in wind speed can cause a large load fluctuation and deformation. Therefore, this control method is particularly suitable for units with long flexible blades.

[0061] According to an embodiment of the present disclosure, the pitch control method may include the following steps:

[0062] like Figure 1 As shown, in step S110, in response to the current output power of the wind turbine generator set reaching the rated power, the change trend of the generator speed of the wind turbine generator set may be determined.

[0063] As mentioned above, constant power control and constant torque control each have their own defects, and thus may not be able to meet the needs of large megawatt units to achieve safe load reduction while ensuring power stability.

[0064] A simulation calculation is performed on a certain land-based platform. The sub-condition (12-g condition) with a wind speed of 14 m / s in the DLC12 condition is selected. Taking the unit output active power and the tower bottom My load as an example, the relationship between the timing diagram of the pitch control after reaching the rated power and the generator speed is shown as follows: Figure 2 and Figure 3 shown.

[0065] Depend on Figure 2 and Figure 3 It can be seen that by comparing the generator speed timing and output power of the unit and the load timing of the tower bottom My under the same operating conditions, it is found that when the generator speed increases or decreases, the unit output power and the tower bottom My fluctuate greatly, and the difference between the two under constant power control and constant torque control is more obvious.

[0066] Based on the above findings, in an embodiment of the present disclosure, when the current output power of the wind turbine generator set reaches the rated power, the change trend of the generator speed of the wind turbine generator set can be determined, so that the load reduction and power stabilization pitch control can be carried out in a targeted manner during the period of generator speed change. Here, the change trend can include an upward trend and a downward trend.

[0067] In this step S110, in one example, the generator speed data at multiple moments within a predetermined time period (e.g., 3 seconds) before the current moment can be obtained, and these generator speed data can be filtered to remove the data points with sudden changes to obtain the filtered speed data, and the speed difference between each pair of adjacent data in the filtered speed data can be used to determine whether the generator is in an increasing or decreasing state within the predetermined time period. For example, if the speed difference is always greater than 0, it can be considered that the speed is in an increasing trend; if the speed difference is always less than 0, it can be considered that the speed is in a decreasing trend.

[0068] In another example, the changing trend of the generator speed of the wind turbine generator set can also be determined in the following way: compare the current measured generator speed with the preset generator speed to determine the speed difference; based on the speed difference, determine the speed difference change rate; compare the speed difference and the speed difference change rate to determine the speed change rate; based on the speed change rate, determine the changing trend of the generator speed.

[0069] Here, the preset generator speed may be, for example, the rated generator speed, the speed difference may be, for example, the overspeed percentage, and accordingly, the speed difference change rate may be, for example, the change rate of the overspeed percentage, wherein the overspeed percentage may be expressed as: overspeed percentage = (measured generator speed - rated generator speed) / rated generator speed × 100%. However, the embodiments of the present disclosure are not limited thereto, and the speed difference and its change rate may also be expressed in other ways.

[0070] As an example, Figure 4A As shown, the measured generator speed can be compared with the preset generator speed, for example, the overspeed percentage of the speed can be obtained, and the overspeed percentage can be differentiated to obtain the change rate of the overspeed percentage.

[0071] For example, fuzzy control can be used to determine whether the speed is rising based on the overspeed percentage and the rate of change of the overspeed percentage. As an example, the logic design idea of ​​fuzzy control may include: taking the overspeed percentage and the rate of change of the overspeed percentage as inputs of the fuzzy controller, and outputting the speed change rate, so as to determine the speed change trend according to the speed change rate. Figure 4B The schematic diagram of fuzzy control logic is shown. The input 1 and input 2 of the fuzzy control are the overspeed percentage and the rate of change of the overspeed percentage respectively. When any one of the overspeed percentage and the rate of change of the overspeed percentage (or the acceleration of the overspeed percentage) is less than 0, the speed change rate is strictly equal to 0. Figure 4B As shown, the greater the overspeed percentage and the rate of change of the overspeed percentage, the greater the speed change rate.

[0072] In one example, when the overspeed percentage and the rate of change thereof are both greater than 0, it can be considered that the rotation speed has an upward trend.

[0073] In another example, the changing trend of the generator speed can be determined in the following manner: in response to the speed change rate satisfying a preset condition, determining that the generator speed is in an upward trend; in response to the speed change rate not satisfying the preset condition, determining that the generator speed is in a downward trend, wherein the preset condition includes: the speed change rate exceeds a preset value, and the duration for which the speed change rate exceeds the preset value exceeds a preset duration.

[0074] Specifically, in this example, only when the speed change rate exceeds the preset value k and lasts for more than a certain period of time, it is considered that the current trend is rising, and a corresponding control logic switching signal is output.

[0075] In addition, in order to reduce unnecessary switching actions and reduce pitch actions to protect the pitch actuator, the speed change rate output by the fuzzy calculation can be protected by a dead zone, and the speed change rate can be limited to a preset rate range (i.e., the above-mentioned dead zone). For example, when multiple speed change rates are obtained in a time series, the data outside the rate range can be removed, and the speed change rate within the rate range can be further judged, such as compared with a preset value to determine the speed change trend.

[0076] In addition, in the above example, the actually measured generator speed may be subjected to an asymmetric moving average filtering process, and the filtered speed data may be compared with the preset generator speed.

[0077] In addition, in the above example, in order to prevent abnormal calculation results due to other reasons, saturation calculation can also be performed on the initial overspeed percentage and overspeed change rate (for example Figure 4A The calculated results can be used as the input of the fuzzy control logic toolbox by using the saturation calculation 1 and saturation calculation 2 in the calculation. Here, saturation calculation refers to a processing method that limits the result between the maximum and minimum values ​​of the range when the result exceeds the preset range during the calculation process. This processing method can avoid data overflow and ensure the correctness of the calculation result. For example, the corresponding limit range can be preset for the overspeed percentage and the rate of change of the overspeed percentage. When the overspeed percentage or the rate of change of the overspeed percentage exceeds the corresponding limit range, the data can be corrected to within the range.

[0078] However, the method of determining the changing trend of the rotation speed is not limited to the above example, and the changing trend of the rotation speed may also be determined according to other mathematical or statistical methods.

[0079] In step S120, the blade pitch of the wind turbine generator set may be controlled based on a control strategy corresponding to the change trend.

[0080] In the examples of the present disclosure, different change trends can be distinguished and different control strategies can be adopted. Here, for each change trend, a corresponding control strategy can be preset.

[0081] Specifically, the control strategy may include a first control strategy and a second control strategy. The first control strategy may include: taking a preset power as a control target for the output power of the wind turbine generator set to control blade pitch, for example, the first control strategy may be but not limited to the existing constant power control; the second control strategy may include: taking a preset torque as a control target for the torque of the generator of the wind turbine generator set to control blade pitch, for example, the second control strategy may be but not limited to the existing constant torque control.

[0082] Here, the preset power may be, for example, the rated power of the unit, and the preset torque may be, for example, a torque given according to actual needs.

[0083] In one example, the blade pitch of the wind turbine generator set can be controlled in the following manner: in response to the change trend being an upward trend, the blade pitch is controlled based on the second control strategy; in response to the change trend being a downward trend, the blade pitch is controlled based on the first control strategy. According to the embodiment of the present disclosure, constant torque control is adopted during the speed increase process, and constant power control is adopted during the speed decrease process, which can achieve better control effect.

[0084] Under both control strategies, the pitch angle of each blade (e.g., blade 1, blade 2, and blade 3) can be obtained, and the reference pitch angle can be obtained through the pitch loop PID controller and provided to the unit for pitch change. In the first control strategy, after the pitch change, the measured power can be obtained to compare with the rated power, thereby achieving constant power control; in the second control strategy, after the pitch change, the measured generator speed can be obtained to calculate the current generator torque and compare it with the preset torque, thereby achieving constant torque control.

[0085] Through the above method, the respective advantages of constant power control and constant torque control of the wind turbine in the full-power section can be combined to achieve adaptive switching of constant power control and constant torque control, reduce the fatigue load of the wind turbine in the full-power section (mainly including tower load and hub center load, which will be described in detail below), and keep the power stable as much as possible.

[0086] In addition, based on the above-mentioned adaptive switching control method, in order to optimize the control implementation method as much as possible and avoid control response delays or control parameter errors caused by switching of control strategies, according to an embodiment of the present disclosure, a parameter design for switching between different control strategies is also provided.

[0087] Specifically, the pitch control method may also include: in response to a change in the variation trend, switching between a first control strategy and a second control strategy by adjusting a preset minimum torque coefficient, a maximum torque coefficient and a switching power coefficient, wherein the minimum torque coefficient and the maximum torque coefficient can be used to determine the control target of the torque of the generator, and the switching power coefficient can be used to determine the control target of the output power of the wind turbine generator set.

[0088] Here, a common control coefficient can be designed for different control strategies, so that the switching between control strategies can be achieved by adjusting the given value of the control coefficient. Specifically, the three control parameters can be added by modifying the pitch change loop PID controller: the minimum torque coefficient P min , Maximum torque coefficient P max and switching power factor P pwdF , to achieve adaptive adjustment strategy according to the operating conditions of the unit, that is, constant power / constant torque control switching.

[0089] As an example, the first control strategy may be switched to by adjusting the minimum torque coefficient to be within a minimum coefficient range, adjusting the maximum torque coefficient to be within a maximum coefficient range, and adjusting the switching power coefficient to a preset power coefficient, wherein the minimum torque coefficient is less than the maximum torque coefficient.

[0090] Specifically, in the constant power control stage, the power control target can be set by adjusting the switching power coefficient to a preset power coefficient. Here, since the embodiments of the present disclosure can be particularly targeted at large-megawatt wind turbines, and the blades of large-megawatt units are longer and flexible, and the towers are taller, under the same wind speed changes, the load changes of large-megawatt units are greater, which will seriously affect the fatigue load of the unit. Therefore, it is necessary to limit the range of changes in the generator torque to reduce the fluctuations in the generator torque.

[0091] According to P=K×ω×T, where P is the real-time power, K is a constant, ω is the real-time speed, and T is the torque, it can be seen that the speed is inversely proportional to the torque. When the speed ω increases, the torque T decreases. Similarly, when the speed ω decreases, the torque T increases. In order to avoid accidents caused by T being too small and less than the load torque, and to avoid accidents caused by T being too large, it is necessary to set the minimum torque coefficient and the maximum torque coefficient to limit the torque range.

[0092] Here, the minimum torque coefficient and the maximum torque coefficient can be selected from a preset minimum coefficient range and a preset maximum coefficient range, respectively. For example, the generator torque lower limit can be set to a times the preset torque) and the upper limit can be set to b times the preset torque, then the minimum torque coefficient P min and the maximum torque coefficient P max Can satisfy a<P min <P max <b.

[0093] As an example, for large megawatt units, since the unit is in the full-power stage, theoretically the speed and power are at the rated state, so the torque remains unchanged. In order to prevent the torque from jumping and causing excessive power fluctuations, thereby affecting the load of key components of the unit, a fluctuation margin of ±10% can be reserved based on the stability judgment experience of large megawatt units, that is, a=90%~100% or a=0.9~1, b=100%~110% or b=1~1.1.

[0094] Specifically, the minimum coefficient range can be: 0.9<P min ≤1; the maximum coefficient range can be: 1≤P max <1.1, and P min <P max .

[0095] In the embodiment of the present disclosure, the switching power coefficient P pwdF The rated power is weighted to obtain the control target of the output power. Here, in the constant power control stage, the control target of the output power can be, for example, the rated power. In this case, the power will remain stable and the switching power coefficient P pwdF It can be 1, but the torque will fluctuate, and it can be guaranteed to be within the range of ±10%, such as the minimum torque coefficient P min >0.9, maximum torque coefficient P max <1.1.

[0096] In addition, the second control strategy can be executed in the following manner: the minimum torque coefficient and the maximum torque coefficient are both adjusted to preset torque coefficients, and the switching power coefficient is adjusted to be within a power coefficient range, wherein the lower limit value of the power coefficient range is greater than the preset power coefficient, and the preset torque coefficient is greater than or equal to the upper limit value of the minimum coefficient range, and is less than or equal to the lower limit value of the maximum coefficient range.

[0097] Specifically, in the constant torque control stage, the minimum torque coefficient and the maximum torque coefficient can be adjusted to the same value so that the control target of the generator torque is the value, thereby achieving constant torque control. min =P max =1.

[0098] Here, since the embodiments of the present disclosure can be particularly targeted at large-megawatt wind turbines, and large-megawatt units have a larger installed capacity, due to the large base, compared with small-power units at the same power fluctuation percentage, their power fluctuation range is larger, which will have a greater impact on the power grid and seriously affect the adaptability of the power grid. Therefore, it is necessary to limit the power fluctuation range. Therefore, the switching power coefficient P can be designed pwdFTo protect the power grid, this coefficient is equivalent to the safety protection coefficient. This coefficient is set to prevent the output active power from being too high under gusts and causing impact on the power grid when the unit switches to constant torque operation.

[0099] In large-megawatt wind turbines, in order to prevent power jumps from causing impacts on the grid, a +15% upward fluctuation margin can be reserved according to the grid adaptability experience requirements. Specifically, c≤P pwdF <d, where c = 100% or c = 1, d = 100% to 115% or d = 1 to 1.15. As an example, the switching power factor P may be set to pwdF =1.1.

[0100] In addition, according to an embodiment of the present disclosure, the pitch control method may further include: in response to the current output power of the wind turbine generator set being less than a preset power limit, executing a step of determining a change trend of a generator speed of the wind turbine generator set; in response to the current output power of the wind turbine generator set being greater than or equal to the power limit, controlling the blades to pitch based on a first control strategy. Here, the power limit may be determined based on a switching power coefficient and a rated power of the wind turbine generator set.

[0101] Specifically, when the unit determines that the output power exceeds the power limit (for example, P pwdF × rated power), it can be forced to switch to the first control strategy, such as switching to constant power control, so as to keep the power stable. After that, the generator speed can be continuously obtained, and whether to switch can be determined again according to the change of the generator speed. After the switch, this coefficient remains unchanged. Therefore, it can be seen that only when the unit is in the second control strategy (such as constant torque control), the coefficient P pwdF It works to prevent power jump and impact on the power grid, for example, 1<P pwdF <1.5.

[0102] As described above, in order to combine the advantages of constant power and constant torque control, the embodiment of the present disclosure can adopt an adaptive control method of semi-constant power / constant torque control to reduce fatigue load on the basis of not over-generating the unit output power. In terms of the implementation of adaptive control, the embodiment of the present disclosure can facilitate switching between different control strategies by designing three coefficients.

[0103] Here, as an example, the advantages of comprehensive constant power control and constant torque control can be achieved by optimizing each coefficient within the above-mentioned coefficient range (such as the minimum coefficient range, the maximum coefficient range and the power coefficient range). In the optimization process, separate simulation tests are required for different models. The parameters such as the blade and tower configuration of each model can be simulated to obtain the optimal coefficient selection corresponding to each model. Table 1 below gives examples of different combinations of the above three coefficient settings. However, the values ​​of the coefficients in Table 1 are only examples, and the values ​​of one or more of these coefficients can also be modified according to actual needs.

[0104] Table 1

[0105]

[0106] According to the embodiments of the present disclosure, a variable pitch control method suitable for the full-generation section of a wind turbine generator set and combining the advantages of constant power and constant torque control can be provided, and adaptive switching between constant power and constant torque control can be achieved by designing control parameters, avoiding the use of pure constant power or pure constant torque control. In this way, on the one hand, the output active power of the unit can be made more stable and over-generation can be reduced compared to a single constant torque control, which is more friendly to the power grid; on the other hand, the fatigue load of key components of the unit (especially the hub center Mx load, blade root My load, tower top Mx load, yaw Mx load, tower bottom My load) can be made smaller than a single constant power control, which is more friendly to the fatigue load of the unit. Through the above improvements, the control method of the embodiments of the present disclosure can reduce the fatigue load of key components of the unit and extend the life of the unit on the basis of ensuring the safety of the unit and the power grid.

[0107] Figure 5 and Figure 6 The schematic diagrams of comparing the output power and tower load under two adaptive switching controls based on a certain land platform are shown respectively. Specifically, based on a certain land unit platform, the unit output active power and tower bottom My load are compared, and the controller parameters are set for the two adaptive switching combinations in Table 1 below and the pure constant power control and pure constant torque control. Under the 14m / s sub-condition (12-g condition) of DLC12, a simulation comparison is performed under the same normal turbulent wind condition, and the verification effect is as follows Figure 5 and Figure 6 In the accompanying drawings, the coefficient P mentioned above pwdF Also indicated by PF.

[0108] Depend on Figure 5 and Figure 6 It can be seen that choosing P min =0.95, P max =1 (i.e. constant torque control is used when the speed increases, and constant power control is used when the speed decreases). Compared with P min =1, Pmax =1.06 (i.e., constant power control is adopted when the speed increases, and constant torque control is adopted when the speed decreases), the unit output active power is relatively stable, the over-generation is small, and the My load at the bottom of the tower is better.

[0109] Based on Table 1, for the parameter P pwdF The same parameter comparison results are as follows Figure 7 and Figure 8 shown.

[0110] Depend on Figure 7 and Figure 8 It can be seen that choosing P pwdF =1 (that is, when the unit is under constant torque control and the current output active power = rated power, it switches to constant power control). pwdF =1.2 (that is, when the unit is under constant torque control and the current output active power = 1.2 times the rated power, it switches to constant power control), the unit output active power is relatively stable, the over-generation is less, and the tower bottom My load is smaller.

[0111] In summary, the constant power / constant torque adaptive switching control parameters can be selected as follows: (1) The minimum torque coefficient P of the unit operation min =0.95; (2) Maximum torque coefficient of the unit operation P max =1; (3) Full-send control mode switching power coefficient P pwdF =1.

[0112] It should be noted that the coefficient selection results here are only based on the simulation results of a certain model platform, and the parameter selection conclusions obtained cannot represent all models. Due to the blade and tower configurations of different models, the optimal parameter selection is different, and separate simulation tests are required for different models. The simulation results are only used as examples to prove that the adaptive switching method according to the embodiment of the present disclosure can combine the advantages of constant power / constant torque.

[0113] In addition, based on the above parameter selection, under the same normal turbulent wind conditions, simulations were performed to compare the active power output of the unit and the My load at the bottom of the tower under constant power, constant torque and adaptive switching control. Fig.9A , Fig. 9B and Fig. 9C shown.

[0114] Fig.9A Schematic diagrams of output active power timing under constant power, constant torque, and adaptive switching control are shown. Fig.9A As shown, by adopting the adaptive switching control method proposed in the present disclosure, relative constant torque control can reduce the overgeneration of the unit, make the output active power relatively stable, and be more friendly to the power grid.

[0115] Here, for all DLC12 operating conditions, from cut-in wind speed to cut-out wind speed, the unit output active power under constant power, constant torque, and adaptive switching control is statistically analyzed, and the results are as follows: Fig. 9B and Fig. 9C ,in, Fig. 9B The maximum active power (DLC12) under constant power, constant torque and adaptive switching control is shown. Fig. 9C The active power standard deviation (DLC12) under constant power, constant torque and adaptive switching control is shown respectively.

[0116] like Fig. 9B and Fig. 9C As shown in the figure, when the unit is in adaptive switching control, at each wind speed in the full-power section (wind speed is between 12m / s and 20m / s), on the one hand, the maximum active power is less than the maximum active power when in constant torque control, and is close to the maximum active power when in constant power control; on the other hand, the standard deviation of active power is less than the standard deviation when in constant torque control, and is close to the standard deviation when in constant power control. This proves that when in adaptive switching control, the output power over-generation is less and the output power fluctuation is smaller, which is beneficial to the unit safety, more friendly to the power grid, and can inherit the advantages of constant power control.

[0117] In addition, the tower bottom My load under constant power, constant torque, and adaptive switching control can also be compared. Fig. 10A As shown, the adaptive switching control method proposed in the present disclosure can reduce the load My at the bottom of the tower compared to constant power control, is more friendly to the fatigue load of the tower, and is beneficial to extending the life of the tower.

[0118] Here, for all DLC12 operating conditions, from the cut-in wind speed to the cut-out wind speed, the load My at the bottom of the unit tower under constant power, constant torque, and adaptive switching control is calculated, and the results are as follows: Fig. 10B and Fig. 10C ,in, Fig. 10B The maximum value of the tower bottom My load (DLC12) under constant power, constant torque, and adaptive switching control is shown. Fig. 10C The standard deviation of the tower bottom My load (DLC12) under constant power, constant torque and adaptive switching control is shown respectively.

[0119] like Fig. 10B and Fig. 10CAs shown in the figure, when the unit is in adaptive switching control, at each wind speed in the full-power section (wind speed is between 12m / s and 20m / s), on the one hand, the maximum value of the My load at the bottom of the tower is less than the maximum value of the My load at the bottom of the tower in constant power control, and is close to the maximum value of the My load at the bottom of the tower in constant torque control; on the other hand, the standard deviation of the My load at the bottom of the tower is less than the standard deviation of the My load at the bottom of the tower in constant power control, and is close to the standard deviation of the My load at the bottom of the tower in constant torque control. This proves that the My load at the bottom of the tower is smaller and less volatile when in adaptive switching control, which is more friendly to the fatigue load of the tower frame, is conducive to extending the life of the unit, and can inherit the advantages of constant torque control.

[0120] In addition, the results of fatigue load on the bottom My of the unit tower under constant power, constant torque and adaptive switching control can be compared as follows: Fig.11 As shown. Fig.11 As shown, based on the current parameters of blades, towers, etc., the constant power / constant torque adaptive switching control proposed in the present disclosure can reduce the fatigue load of the tower bottom My by about 5%.

[0121] Fig. 12A Schematic diagrams of the wheel hub center Mx load timing under constant power, constant torque, and adaptive switching control are shown. Fig. 12A As shown in the figure, the adaptive switching control can reduce the hub center Mx load compared to the constant power control, is more friendly to the hub fatigue load, and is beneficial to extending the spindle life.

[0122] Here, for all DLC12 working conditions, from the cut-in wind speed to the cut-out wind speed, the unit hub center Mx load under constant power, constant torque, and adaptive switching control is statistically analyzed, and the results are as follows: FIG. 12B to FIG. 12D As shown, Fig. 12B The maximum value of the hub center Mx load (DLC12) under constant power, constant torque, and adaptive switching control is shown. Fig. 12C The average value of the hub center Mx load (DLC12) under constant power, constant torque, and adaptive switching control is shown. Fig.12D The standard deviation of the hub center Mx load (DLC12) under constant power, constant torque, and adaptive switching control is shown.

[0123] like FIG. 12B to FIG. 12DAs shown in the figure, when the unit is in adaptive switching control, at each wind speed in the full-power section (wind speed is between 12m / s and 20m / s), first, the maximum value of the hub center Mx load is less than the maximum value of the hub center Mx load in constant power control, and is close to the maximum value of the hub center Mx load in constant torque control; second, the mean value of the hub center Mx load is less than the mean value of the hub center Mx load in constant power control and constant torque control; third, the standard deviation of the hub center Mx load is less than the standard deviation of the hub center Mx load in constant power control, and is close to the standard deviation of the hub center Mx load in constant torque control. This proves that the hub center Mx load is smaller and less volatile when in adaptive switching control, which is more friendly to the hub fatigue load, is conducive to extending the life of the main shaft, and can inherit the advantages of constant torque control.

[0124] Fig.13 The figure shows the comparison of fatigue loads of key components of the unit under constant power / constant torque / adaptive switching control. Fig.13 In the figure, the load reduction effect in the red frame (hub center Mx, blade root My, tower top Mx, yaw Mx, tower bottom My) is more obvious. In addition, there is also a load reduction effect in other directions.

[0125] Specifically, taking the fatigue load of the tower bottom My as an example, the fatigue load of the tower bottom My under constant power, constant torque, and adaptive switching control is compared. Fig.13 As shown in the last figure in , based on the current parameters of blades, towers, etc., the constant power / constant torque adaptive switching control method proposed in the present disclosure can reduce the fatigue load of the tower bottom My by about 5%.

[0126] As mentioned above, select P min =0.95, P max =1 (i.e. constant torque control is used when the speed increases, and constant power control is used when the speed decreases). Compared with P min =1, P max =1.06 (i.e. constant power control is used when the speed increases, and constant torque control is used when the speed decreases), the unit output active power is relatively stable, the over-generation is small, and the My load at the bottom of the tower is better. In addition, select P pwdF =1 (when the unit is under constant torque control and the current output active power = rated power, switch to constant power control), compared with P pwdF =1.2 (when the unit is under constant torque control and the current output active power = 1.2 times the rated power, it switches to constant power control), the unit output active power is relatively stable, the over-generation is less, and the load My at the bottom of the tower is smaller. In addition, in the above simulation result diagram, the differences between different control strategies are intended to be compared, so the specific units or values ​​of each horizontal and vertical coordinates are not marked.

[0127] From the above simulation analysis, it can be seen that constant power / constant torque switching is performed when the speed changes, which can prevent the wind turbine from outputting too much active power, causing over-generation or even damaging the converter, improve grid friendliness, and reduce the fatigue load of key components of the unit, extend the life of the unit, and combine the advantages of constant power control and constant torque control. In addition, the constant power / constant torque adaptive switching of the unit can be achieved by modifying the controller to set three sets of coefficients and set the action range of the parameters.

[0128] According to a second aspect of an embodiment of the present disclosure, a control system for a wind turbine is provided, the control system comprising: at least one processor; and at least one memory storing computer executable instructions, wherein the computer executable instructions, when executed by the at least one processor, prompt the at least one processor to execute the variable pitch control method for the wind turbine as described in the embodiment of the present disclosure.

[0129] The control system may include a computer device. Specifically, the pitch control method of the wind turbine generator set may be executed by the computer device.

[0130] As an example, the computer device can be a PC, a tablet device, a personal digital assistant, a smart phone, or other device capable of executing the above-mentioned instruction set. Here, the computer device is not necessarily a single electronic device, but can also be any device or circuit that can execute the above-mentioned instructions (or instruction sets) individually or jointly. The computer device can also be part of an integrated control system or system manager, or can be configured as a portable electronic device that is interconnected with a local or remote (e.g., via wireless transmission) interface.

[0131] In a computer device, a processor may include a central processing unit (CPU), a graphics processing unit (GPU), a programmable logic device, a dedicated processor system, a microcontroller or a microprocessor. As an example and not limitation, a processor may also include an analog processor, a digital processor, a microprocessor, a multi-core processor, a processor array, a network processor, etc.

[0132] The processor can execute instructions or codes stored in the memory, wherein the memory can also store data. Instructions and data can also be sent and received through the network via the network interface device, wherein the network interface device can adopt any known transmission protocol.

[0133] The memory may be integrated with the processor, for example, RAM or flash memory is arranged within an integrated circuit microprocessor or the like. In addition, the memory may include a separate device, such as an external disk drive, a storage array, or any other storage device that can be used by a database system. The memory and the processor may be operatively coupled, or may communicate with each other, such as through an I / O port, a network connection, etc., so that the processor can read files stored in the memory.

[0134] In addition, the computer device may also include a video display (such as a liquid crystal display) and a user interaction interface (such as a keyboard, a mouse, a touch input device, etc.) All components of the computer device may be connected to each other via a bus and / or a network.

[0135] According to a third aspect of an embodiment of the present disclosure, a wind turbine generator set is provided. The wind turbine generator set includes the control system of the wind turbine generator set according to the embodiment of the present disclosure.

[0136] According to a fourth aspect of an embodiment of the present disclosure, a computer-readable storage medium is provided. When instructions in the computer-readable storage medium are executed by a processor of an electronic device, the electronic device is enabled to execute the variable pitch control method of a wind turbine generator set according to an embodiment of the present disclosure.

[0137] Specifically, the pitch control method of a wind turbine generator set according to an embodiment of the present disclosure can be written as a computer program and stored on a computer-readable storage medium. When the instructions in the computer-readable storage medium are executed by at least one processor, the at least one processor is prompted to execute the pitch control method of the wind turbine generator set according to the exemplary embodiment of the present disclosure. 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, non-volatile 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.

[0138] According to a fifth aspect of an embodiment of the present disclosure, a computer program product is provided, which includes computer executable instructions. When the computer executable instructions are executed by at least one processor, the variable pitch control method of the wind turbine generator set according to the embodiment of the present disclosure is implemented.

[0139] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. The present disclosure is intended to cover any variations, uses or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The description and examples are to be considered exemplary only, and the true scope and spirit of the present disclosure are indicated by the claims.

[0140] In addition, it should be noted that although several examples of each step are described above with reference to specific drawings, it should be understood that the embodiments of the present disclosure are not limited to the combinations given in the examples, and the steps appearing in different drawings may be combined, and the order of execution of the steps may be changed, which is not exhaustive here.

[0141] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

[0142] The specific implementation methods of the present disclosure have been described in detail above. Although some embodiments have been shown and described, those skilled in the art should understand that these embodiments may be modified and varied without departing from the principles and spirit of the present disclosure, the scope of which is defined by the claims and their equivalents. These modifications and variations should also be within the scope of protection of the claims of the present disclosure.

Claims

1. A variable pitch control method for a wind turbine generator set, characterized in that: The pitch control method comprises: In response to the current output power of the wind turbine generator set reaching the rated power, determining a change trend of the generator speed of the wind turbine generator set; Based on the control strategy corresponding to the change trend, the blade pitch of the wind turbine generator set is controlled, wherein different change trends correspond to different control strategies, and the control strategies include a first control strategy and a second control strategy, The first control strategy includes: taking a preset power as a control target of the output power of the wind turbine generator set, controlling the blade pitch change, The second control strategy includes: taking a preset torque as a control target of the torque of the generator of the wind turbine generator set to control the blade pitch change.

2. The pitch control method according to claim 1, characterized in that: The blade pitch of the wind turbine generator set is controlled by: In response to the change trend being an upward trend, controlling the blade pitch change based on the second control strategy; In response to the changing trend being a downward trend, the blade pitch is controlled based on the first control strategy.

3. The pitch control method according to claim 1 or 2, characterized in that: The pitch control method further includes: In response to the change in the variation trend, the first control strategy and the second control strategy are switched by adjusting the preset minimum torque coefficient, the maximum torque coefficient and the switching power coefficient, The minimum torque coefficient and the maximum torque coefficient are used to determine a control target of the torque of the generator, and the switching power coefficient is used to determine a control target of the output power of the wind turbine generator set.

4. The pitch control method according to claim 3, characterized in that: Switch to the first control strategy by: The minimum torque coefficient is adjusted to be within a minimum coefficient range, the maximum torque coefficient is adjusted to be within a maximum coefficient range, and the switching power coefficient is adjusted to a preset power coefficient, Wherein, the minimum torque coefficient is smaller than the maximum torque coefficient.

5. The pitch control method according to claim 4, characterized in that: The second control strategy is implemented in the following way: The minimum torque coefficient and the maximum torque coefficient are both adjusted to preset torque coefficients, and the switching power coefficient is adjusted to be within a power coefficient range, The lower limit value of the power coefficient range is greater than the preset power coefficient, and the preset torque coefficient is greater than or equal to the upper limit value of the minimum coefficient range and less than or equal to the lower limit value of the maximum coefficient range.

6. The pitch control method according to claim 5, characterized in that: The pitch control method further includes: In response to the current output power of the wind turbine generator set being less than a preset power limit, executing the step of determining a change trend of a generator speed of the wind turbine generator set; In response to the current output power of the wind turbine generator set being greater than or equal to the power limit, based on the first control strategy, controlling the blades to perform pitch change; The power limit is determined based on the switching power factor and the rated power of the wind turbine generator set.

7. The pitch control method according to claim 1, characterized in that: The variation trend of the generator speed of the wind turbine generator set is determined by: Compare the current measured generator speed with the preset generator speed to determine the speed difference; Based on the speed difference, determining a speed difference change rate; Determine the speed change rate by using the speed difference and the speed difference change rate; Based on the rotational speed change rate, a change trend of the generator rotational speed is determined.

8. The pitch control method according to claim 7, characterized in that: The variation trend of the generator speed is determined by: In response to the rotation speed change rate satisfying a preset condition, determining that the generator rotation speed is in an upward trend; In response to the speed change rate not satisfying the preset condition, determining that the generator speed is in a downward trend, The preset conditions include: the speed change rate exceeds a preset value, and the duration for which the speed change rate exceeds the preset value exceeds a preset duration.

9. The pitch control method according to claim 1, characterized in that: The wind turbine generator set is a large megawatt wind turbine generator set, the single unit capacity of the wind turbine generator set is greater than or equal to 6 megawatts, the blades of the wind turbine generator set are long flexible blades, the length of the long flexible blades is greater than or equal to 85 meters, and the impeller diameter of the wind turbine generator set is greater than or equal to 175 meters.

10. A control system for a wind turbine generator set, characterized in that: The control system comprises: at least one processor; at least one memory storing computer executable instructions, Wherein, when the computer executable instructions are executed by the at least one processor, the at least one processor is prompted to execute the pitch control method of the wind turbine generator set according to any one of claims 1 to 9.

11. A wind turbine generator set, characterized in that: The wind turbine generator set comprises the control system of the wind turbine generator set according to claim 10 .

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