A method for starting control of a wind turbine main control system

Abstract

This invention provides a start-up control method for a wind turbine main control system, belonging to the field of wind turbine main control system control technology. The start-up control is divided into four control states: standby control state, start-up control state I, start-up control state II, and grid-connected control state. The standby control state and start-up control state I switch between each other, as do start-up control state I and start-up control state II, with start-up control state II switching to grid-connected control state. This invention effectively improves the accuracy of start-up condition judgment, increases the success rate of start-up through the wind turbine tower's resonance speed range, and reduces the operating time in the wind turbine tower's resonance speed range. Therefore, it effectively improves the start-up and grid-connection success rate of wind turbines, reduces the risk of wind turbine tower fatigue damage, and increases power generation.

Description

Technical Field

[0001] This invention belongs to the field of wind turbine main control system control technology, specifically relating to a start-up control method for a wind turbine main control system. Background Technology

[0002] When a wind turbine is in standby mode without any faults, the main control system of the wind turbine usually determines whether the wind turbine has met the start-up conditions by measuring whether the wind speed has reached the start-up wind speed or by detecting whether the speed at a certain pitch angle has reached a set threshold. Once the start-up conditions are met, the main control system of the wind turbine controls the wind turbine to start up: controlling the pitch to open the pitch and increase the speed to the grid-connected speed to complete grid connection.

[0003] Problems with existing technology: The start-up wind speed is usually set to a fixed value, without taking into account the different wind energy at the same wind speed under different air densities. This may lead to excessively long standby time for wind turbines, resulting in power generation loss and frequent start-up and grid connection failures. During the start-up process, the wind speed change is not properly monitored before and during the resonant speed range of the wind turbine tower. This may cause the generator speed to remain in the resonant speed range of the wind turbine tower for a long time due to the decrease in wind speed, accelerating the fatigue damage of the wind turbine tower.

[0004] Therefore, it is necessary to explore an innovative start-up control method for the main control system of wind turbines to improve the start-up and grid connection success rate of wind turbines, reduce the risk of fatigue damage to wind turbine towers, and increase power generation. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems in the prior art and to provide a start-up control method for the main control system of a wind turbine. This invention effectively improves the start-up and grid connection success rate of wind turbines, reduces the risk of fatigue damage to wind turbine towers, and increases power generation.

[0006] This invention is achieved through the following technical solution: A start-up control method for a wind turbine main control system, characterized in that: the start-up control is divided into 4 control states, including standby control state, start-up control state I, start-up control state II and grid connection control state; In standby control mode, control the pitch to the standby pitch angle and obtain the average measured wind speed during standby control mode. And calculate the start-up wind speed Equivalent start-up wind speed based on actual air density When the average measured wind speed > Actual air density equivalent start-up wind speed And the duration exceeds the set value Switching from standby control state to power-on control state I; During startup control state I, the generator speed is controlled by pitch control to achieve the target generator speed for startup control state I. And obtain the average theoretical wind speed. ; When the average theoretical wind speed > Actual air density equivalent start-up wind speed And the duration exceeds the set value Switch from start-up control state I to start-up control state II; In start-up control state II, the generator speed changes from the target generator speed in start-up control state I. Towards grid connection speed Improve and obtain the average theoretical wind speed under startup control state II. ; When the target generator speed reaches the grid connection speed Switch to grid-connected control mode; When the duration of start-up control state I exceeds the maximum allowable time of start-up control state I. The system switches from power-on control state I to standby control state. When the startup control state II runs Exceeding the maximum running time of Start-up Control State II Or the operating time within the resonant speed range of the wind turbine tower. Exceeding the maximum operating time within the resonant speed range of the wind turbine tower ,and <Actual air density equivalent start-up wind speed> Switch from start-up control state II to start-up control state I.

[0007] More preferably, the standby control state includes the following control steps: S11, control the pitch angle to the standby pitch angle; S12. Calculate the actual air density based on altitude and ambient temperature. ; S13. Based on actual air density Calculate start-up wind speed Equivalent start-up wind speed based on actual air density ; S14. State switching judgment in standby control mode: dynamically calculate and measure wind speed. Average measured wind speed within a set time window Determine whether the conditions for switching from standby control state to start-up control state I are met. If they are met, switch the control state to start-up control state I; otherwise, repeat steps S12-S14.

[0008] More preferably, in step S12, the actual air density is calculated. as follows: ; in: This is the standard atmospheric pressure at sea level, with a value of 101325 Pa. This is the temperature at sea level in the standard atmospheric pressure model, with a value of 288.15 K; This is the ambient temperature, expressed in °C. This refers to the altitude at the center of the wind turbine hub, measured in meters (m). It is the universal gas constant, with a value of 8.314 J / (mol·K); This is the molar mass of air, with a value of approximately 0.0289644 kg / mol; It is the vertical temperature lapse rate, with a value of approximately 0.0065 K / m; This is the acceleration due to gravity, with a value of approximately 9.8 m / s². 2 .

[0009] More preferably, in step S13, the equivalent start-up wind speed based on the actual air density is calculated. as follows: ; in This is the actual air density. Start-up wind speed The corresponding air density.

[0010] More preferably, the start-up control state I includes the following control steps: S21. Controlling generator speed via pitch control: Target speed is the generator speed under start-up control state I. ; S22. Theoretical wind speed calculation enable judgment: When the generator speed reaches the target generator speed under start-up control state I. Then, the theoretical wind speed calculation enable is set to 1 and kept at 1 under the start-up control state I. If the theoretical wind speed calculation enable is 1, proceed to step S23; otherwise, proceed to step S21. S23. Calculate the theoretical wind speed under start-up control state I iteratively based on the real-time operating data and power balance equation of the wind turbine. v 1 Theory ; S24. State switching judgment under start-up control state I: Dynamic calculation of theoretical wind speed. Average theoretical wind speed within a set time window The running time of start-up control state I is counted, and it is determined whether the conditions for switching from start-up control state I to start-up control state II are met. If the conditions are met, the control state is switched to start-up control state II. If the conditions are not met, it is further determined whether the conditions for switching from start-up control state I to standby control state are met. If the conditions are met, the theoretical wind speed calculation enable is set to 0, and the control state is switched to standby control state. If the conditions are not met, the process proceeds to step S21.

[0011] More preferably, the start-up control state II includes the following control steps: S31. Controlling generator speed via pitch control: Target speed is the grid-connected speed. ; S32. Calculate the theoretical wind speed under start-up control state II based on real-time operating data and power balance equations of the wind turbine. v2 Theory ; S33. State switching judgment under start-up control state II: Dynamic calculation of theoretical wind speed. Average theoretical wind speed within a set time window Statistical analysis of the running time of start-up control state II Statistical analysis of the operating time within the resonant speed range of the wind turbine tower. Determine whether the conditions for switching from start-up control state II to grid-connected control state are met. If they are met, switch the control state to grid-connected control state. If not, further determine whether the conditions for switching from start-up control state II to start-up control state I are met. If they are met, switch the control state to start-up control state I. Otherwise, proceed to step S31.

[0012] More preferably, in step S23, the theoretical wind speed is calculated iteratively based on the real-time operating data of the wind turbine and the power balance equation. In step S32, the theoretical wind speed is calculated iteratively based on the real-time operating data of the wind turbine and the power balance equation. The power balance equation is as follows: ; in: This refers to the actual air density, in kg / m³. Pi; The radius of the wind turbine is in meters (m). Wind speed, unit: m / s; Moment of inertia, unit: kg·m²; The angular velocity of the wind turbine, in rad / s; Angular acceleration of the wind turbine, unit: rad / s²; For the tip speed ratio, ; The pitch angle of the wind turbine blade; Tip speed ratio and propeller pitch angle The corresponding wind energy utilization coefficient; For power loss; ,coefficient k Design parameters for wind turbine units.

[0013] More preferably, the theoretical wind speed is calculated iteratively based on the real-time operating data of the wind turbine and the power balance equation. The steps are as follows: S231, Iterative calculation of theoretical wind speed initialization; S232. Correct the theoretical wind speed according to the set step size. ; S233, Calculate theoretical wind speed The absolute value of the numerical difference between the left and right sides of the corresponding power balance equation ; S234. Determine whether the theoretical wind speed iterative calculation has ended. If the theoretical wind speed iterative calculation has ended, proceed to step S235. If the theoretical wind speed iterative calculation has not ended, proceed to step S232. S235, Calculate theoretical wind speed .

[0014] More preferably, in step S231, the initialization content includes: Theoretical wind speed Initialize to the current wind speed ; The calculated wind speed is the theoretical wind speed. The left side of the power balance equation is numerical ; Calculate the values ​​on the right side of the power balance equation. ; Calculate the absolute value of the numerical difference between the left and right sides of the power balance equation. ; Determine the theoretical wind speed Iterative correction direction: if > Theoretical wind speed The iterative correction direction is negative; otherwise, the theoretical wind speed... The direction of iterative correction is positive.

[0015] More preferably, in step S232, the specific method is as follows: if the theoretical wind speed The direction of iterative correction is positive. If the theoretical wind speed The direction of iterative correction is negative. , To set the step size.

[0016] More preferably, in step S233, the calculation is as follows: The calculated wind speed is the theoretical wind speed. The values ​​on the left side of the power balance equation: ; Calculate the values ​​on the right side of the power balance equation: ; Calculate the absolute value of the numerical difference between the left and right sides of the power balance equation: .

[0017] More preferably, step S234 specifically includes: if > Then the theoretical wind speed iterative calculation ends, and the process moves to step S235. If < If the theoretical wind speed iterative calculation is not completed, then... Assigned value , ,Will Assigned value , Then proceed to step S232.

[0018] More preferably, in step S235, the calculation is as follows: .

[0019] The beneficial effects of this invention are as follows: In standby control mode, the start-up condition is determined by comparing the average measured wind speed with the equivalent start-up wind speed based on the actual air density. In start-up control mode I, the start-up condition is determined based on the calculated average theoretical wind speed. The calculated average theoretical wind speed is compared with the actual air density equivalent start-up wind speed to further determine whether there is sufficient wind energy to support the passage through the resonant speed zone of the wind turbine tower. During start-up control state II, the calculated average theoretical wind speed is used as the basis for further analysis. This invention provides timeout protection by statistically analyzing the start-up control state II running time and the running time within the wind turbine tower resonance speed range. This effectively improves the accuracy of start-up condition judgment, increases the success rate of start-up through the wind turbine tower resonance speed range, reduces the running time within the wind turbine tower resonance speed range, and thus effectively improves the start-up and grid connection success rate of wind turbines, reduces the risk of wind turbine tower fatigue damage, and increases power generation. Attached Figure Description

[0020] Figure 1The diagram shows four control states of the start-up control method of the wind turbine main control system of the present invention. Figure 2 This is a diagram illustrating the control steps for the standby control state of the present invention. Figure 3 This is a diagram illustrating the control steps of the startup control state I of the present invention; Figure 4 This is a control step diagram for the start-up control state II of the present invention; Figure 5 This is a table of wind energy utilization coefficients for a certain wind turbine unit of the present invention. Schematic diagram; Figure 6 The present invention calculates the theoretical wind speed iteratively based on real-time operating data of wind turbines and power balance equations. The steps of the method. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0022] Example 1 A start-up control method for a wind turbine main control system, wherein the main body executing the method is the wind turbine main control system, such as... Figure 1 As shown, the start-up control is divided into four control states, including standby control state, start-up control state I, start-up control state II, and grid connection control state. In standby control mode, control the pitch to the standby pitch angle and obtain the average measured wind speed during standby control mode. And calculate the start-up wind speed Equivalent start-up wind speed based on actual air density When the average measured wind speed > Actual air density equivalent start-up wind speed And the duration exceeds the set value Switching from standby control state to power-on control state I; in this embodiment Set to 100s; During startup control state I, the generator speed is controlled by pitch control to achieve the target generator speed for startup control state I. And calculate the average theoretical wind speed under start-up control state I. ; When the average theoretical wind speed > Actual air density equivalent start-up wind speed And the duration exceeds the set value Switching from startup control state I to startup control state II; in this embodiment Set to 30 seconds; In start-up control state II, the generator speed changes from the target generator speed in start-up control state I. Towards grid connection speed Increase and calculate the average theoretical wind speed under start-up control state II. ; When the target generator speed reaches the grid connection speed Switch to grid-connected control mode; When the duration of start-up control state I exceeds the maximum allowable time of start-up control state I. The system switches from power-on control state I to standby control state; in this embodiment... Set it to 180s.

[0023] When the startup control state II runs Exceeding the maximum running time of Start-up Control State II Or the operating time within the resonant speed range of the wind turbine tower. Exceeding the maximum operating time within the resonant speed range of the wind turbine tower ,and <Actual air density equivalent start-up wind speed> The system switches from startup control state II to startup control state I. This embodiment... Set to 120s Set to 60s; In this embodiment, the standby control state refers to a situation where the wind turbine is fault-free but the wind speed is not up to standard. The pitch angle is controlled to the standby pitch angle to wait for the wind, and the speed is temporarily not increased for grid connection.

[0024] In this embodiment, during standby control, the start-up condition is determined by comparing the average measured wind speed with the equivalent start-up wind speed based on the actual air density. During start-up control state I, the start-up condition is determined based on the obtained average theoretical wind speed. The wind speed is then compared with the equivalent start-up wind speed based on actual air density to further determine whether there is sufficient wind energy to support the passage through the resonant speed zone of the wind turbine tower. During start-up control state II, the average theoretical wind speed is used as the basis for further assessment. This invention provides timeout protection by statistically analyzing the start-up control state II running time and the running time within the wind turbine tower resonance speed range. This effectively improves the accuracy of start-up condition judgment, increases the success rate of start-up through the wind turbine tower resonance speed range, reduces the running time within the wind turbine tower resonance speed range, and thus effectively improves the start-up and grid connection success rate of wind turbines, reduces the risk of wind turbine tower fatigue damage, and increases power generation.

[0025] Example 2 This embodiment further elaborates and supplements the implementation of the present invention based on Embodiment 1.

[0026] like Figure 2 As shown, the standby control state includes the following control steps: S11, control the pitch angle to the standby pitch angle; Preferably, the wind turbine main control system controls the wind turbine pitch system to control the pitch angle to the standby angle of 90° and keeps the pitch angle at 90°.

[0027] S12. Calculate the actual air density based on altitude and ambient temperature. ; In step S12, the actual air density is calculated. as follows: ; in: This is the standard atmospheric pressure at sea level, with a value of 101325 Pa. This is the temperature at sea level in the standard atmospheric pressure model, with a value of 288.15 K; This is the ambient temperature, expressed in °C. This refers to the altitude at the center of the wind turbine hub, measured in meters (m). It is the universal gas constant, with a value of 8.314 J / (mol·K); This is the molar mass of air, with a value of approximately 0.0289644 kg / mol; It is the vertical temperature lapse rate, with a value of approximately 0.0065 K / m; This is the acceleration due to gravity, with a value of approximately 9.8 m / s². 2 .

[0028] Ambient temperature The altitude at the center of the wind turbine hub is monitored in real time by the wind turbine's main control system using temperature sensors such as PT100. The location is determined by the actual installation location of the wind turbine.

[0029] S13. Based on actual air density Calculate start-up wind speed Equivalent start-up wind speed based on actual air density ; In step S13, the equivalent start-up wind speed based on the actual air density is calculated. as follows: ; in This is the actual air density. Start-up wind speed The corresponding air density. and These are all wind turbine design parameters. This embodiment describes the design of a specific wind turbine. Corresponding start-up wind speed at 1.05 kg / m³ The velocity is 3.5 m / s, and the actual measured air density on site is... When the wind speed is 1.2 kg / m³, the equivalent starting wind speed is calculated. Approximately 3.348 m / s; S14. State switching judgment in standby control mode: dynamically calculate and measure wind speed. Average measured wind speed within a set time window The system determines whether the conditions for switching from standby control state to startup control state I are met. If the conditions are met, the control state is switched to startup control state I; otherwise, steps S12-S14 are repeated. In this embodiment, the time window length is set to 30 seconds.

[0030] In this embodiment, the main control system receives the measured values ​​collected by the wind speed sensor in real time, caches 30 consecutive data points in a 30-second window, sums all wind speed data within the current window, and divides by the number of wind speed data points to obtain the average measured wind speed within the set time window. When new wind speed data is collected, the earliest wind speed data in the window is automatically removed, and the new data is added to the cache, ensuring that the window always contains all the measured values ​​within the most recent set time period, thus achieving dynamic calculation of the measured wind speed. The average measured wind speed within a set time window.

[0031] In this embodiment, the actual air density is calculated using altitude and ambient temperature, combined with a formula. Then, by calculating the equivalent start-up wind speed corresponding to the actual air density, based on the design air density of a certain wind turbine unit... Corresponding start-up wind speed at 1.05 kg / m³ The velocity is 3.5 m / s, and the air density at the scene is... When the wind speed is 1.2 kg / m³, the equivalent starting wind speed is calculated. The wind speed is approximately 3.348 m / s. At this point, there's no need to wait for the wind speed to reach the fixed 3.5 m / s; as long as it reaches 3.348 m / s and remains there for more than the set value... This will meet the start-up conditions and avoid standby losses under high air density; if the on-site air density is lower than the wind turbine's design air density... The equivalent start-up wind speed will increase, avoiding grid connection failure due to insufficient wind energy when starting up under low air density. Therefore, it can start up in time when there is enough wind energy, and continue to standby when there is insufficient wind energy, which can both increase power generation and reduce the probability of start-up failure.

[0032] And wind speed is measured through dynamic calculation. Average measured wind speed within a set time window It filters out random fluctuations in instantaneous wind speed, using stable wind speed over a period of time as the criterion, while the control state switching condition needs to meet the average measured wind speed. > Actual air density equivalent start-up wind speed And the duration exceeds the set value. This further ensures that the start-up judgment is based on continuous and stable wind energy conditions. If the switching conditions are not met, the process returns to step S12 to recalculate and form a closed loop. Since the calculation of actual air density is affected by ambient temperature, which changes dynamically with seasons, day and night, and weather, the latest actual air density and corresponding equivalent start-up wind speed need to be recalculated to adapt to the impact of environmental changes on start-up conditions in real time. This avoids start-up judgment deviations caused by environmental changes and provides a reliable wind energy judgment basis for switching from standby control state to start-up control state I. This reduces the probability of switching from start-up control state I to standby control state due to insufficient wind energy, avoids repeated start-up processes, and improves overall start-up efficiency.

[0033] Example 3 This embodiment further elaborates and supplements the implementation of the present invention based on Embodiment 1 or Embodiment 2.

[0034] like Figure 3 As shown, the start-up control state I includes the following control steps: S21. Controlling generator speed via pitch control: Target speed is the generator speed under start-up control state I. ; Start-up control state I Target generator speed Below the lower limit of the resonant speed range of the wind turbine tower, preferably, in this embodiment... =Lower limit of the resonant speed range of wind turbine tower × 0.9.

[0035] S22. Theoretical wind speed calculation enable judgment: when the generator speed... Reaching the target generator speed in start-up control state I Then, the theoretical wind speed calculation enable is set to 1 and kept at 1 under the start-up control state I. If the theoretical wind speed calculation enable is 1, proceed to step S23; otherwise, proceed to step S21. S23. Calculate the theoretical wind speed under start-up control state I iteratively based on the real-time operating data and power balance equation of the wind turbine. ; S24. State switching judgment under start-up control state I: Dynamic calculation of theoretical wind speed. Average theoretical wind speed within a set time window The system counts the running time of startup control state I and determines whether the conditions for switching from startup control state I to startup control state II are met. If met, the control state is switched to startup control state II. If not, it further determines whether the conditions for switching from startup control state I to standby control state are met. If met, the theoretical wind speed calculation enable is set to 0, and the control state is switched to standby control state. If not met, the process proceeds to step S21. In this embodiment, the window length is set to 30 seconds.

[0036] In this embodiment, the start-up control state I stabilizes the generator speed at the target generator speed through pitch control. The speed is kept below the lower limit of the resonance speed range of the wind turbine tower, which avoids the generator speed from entering the resonance range too early in the initial stage of startup, reduces the risk of tower fatigue caused by resonance, and extends the service life of the equipment structure.

[0037] Wind speed sensors are typically installed behind the rotor of a wind turbine. When the rotor speed is high, the wind speed is affected by factors such as wake and tower shadow effects. There is a discrepancy between the actual wind speed at the wind turbine and the measured wind speed; therefore, an average wind speed measurement is used. Equivalent start-up wind speed to actual air density The comparison as the judgment condition for switching from start-up control state I to start-up control state II is not accurate enough; using the average theoretical wind speed is necessary. Equivalent start-up wind speed to actual air density Compared to the judgment condition for switching from start-up control state I to start-up control state II, it can more accurately assess whether there is enough wind energy to support passing through the resonant speed zone of the wind turbine tower.

[0038] The theoretical wind speed under start-up control state I is calculated iteratively based on real-time operating data of the wind turbine and the power balance equation. Cache 30 theoretical wind speeds in chronological order. For all theoretical wind speeds within the current sliding window Summation, and calculation of the average theoretical wind speed within the set window length. Once the new theoretical wind speed calculation is completed, the oldest theoretical wind speed value in the cache is automatically removed, and the newly calculated theoretical wind speed value is added to the cache.

[0039] The start-up control state I sets the maximum allowable running time. If the start-up control state I does not meet the conditions for switching to start-up control state II and the continuous operation exceeds the timeout, the theoretical wind speed calculation enable will be set to 0, and the control state will be switched to standby control state. This reduces unnecessary power consumption caused by the wind turbine operating in start-up control state I due to insufficient wind power, and reduces mechanical wear on pitch bearings and other components.

[0040] More preferably, such as Figure 4As shown, the start-up control state II includes the following control steps: S31. Controlling generator speed via pitch control: Target speed is the grid-connected speed. ; The wind turbine's main control system adjusts the pitch angle by controlling the wind turbine's pitch system, thereby controlling the wind turbine's speed to reach the grid-connected speed. .

[0041] S32. Iteratively calculate the theoretical wind speed based on real-time operating data of the wind turbine and the power balance equation. ; S33. State switching judgment under start-up control state II: Dynamic calculation of theoretical wind speed. Average theoretical wind speed within a set time window Statistical analysis of the running time of start-up control state II Statistical analysis of the operating time within the resonant speed range of the wind turbine tower. The system determines whether the conditions for switching from startup control state II to grid-connected control state are met. If met, the control state is switched to grid-connected control state. If not, it further determines whether the conditions for switching from startup control state II to startup control state I are met. If met, the control state is switched to startup control state I; otherwise, it proceeds to step S31. In this embodiment, the time window length is set to 30 seconds.

[0042] In this embodiment, the start-up control state II targets the grid-connected speed and adjusts the speed by controlling the pitch angle of the pitch control system. When the generator speed reaches the grid-connected speed, it switches to the grid-connected control state. The grid-connected control includes: the wind turbine main control system adjusts the pitch angle of the wind turbine pitch control system to maintain the generator speed at the grid-connected speed. Within the grid-connected speed range of the converter, the main control system controls the converter to complete the grid connection of the wind turbine, and exits the start-up control after the grid connection is completed.

[0043] The theoretical wind speed under start-up control state II is calculated iteratively based on real-time operating data of the wind turbine and the power balance equation. Cache 30 theoretical wind speeds in chronological order. For all theoretical wind speeds within the current sliding window Summation, and calculation of the average theoretical wind speed within the set window length. Once the new theoretical wind speed calculation is completed, the oldest theoretical wind speed value in the cache is automatically removed, and the newly calculated theoretical wind speed value is added to the cache.

[0044] Start-up control state II has a preset maximum running time, and the running time is counted in real time. If the maximum running time of start-up control state II is exceeded and the average theoretical wind speed is also exceeded, the operation will be stopped. The actual air density equivalent start-up wind speed indicates that the current wind energy cannot support grid connection. Therefore, we should immediately switch back to start-up control state I instead of staying in start-up control state II for an ineffective speed increase process. This reduces the ineffective operating time and allows the wind turbine to return to a more reasonable state, waiting for the wind energy conditions to improve before restarting the speed increase.

[0045] Under start-up control state II, the operating time within the resonant speed range of the wind turbine tower will be counted in real time, and the maximum operating time within the resonant speed range of the wind turbine tower will be preset. Once the maximum operating time within the resonant speed range of the wind turbine tower is exceeded and the average theoretical wind speed is exceeded, the wind turbine will be controlled. The actual air density equivalent start-up wind speed indicates that the current wind energy is insufficient to support a rapid departure from the wind turbine tower's resonance speed range. The start-up control state I should be switched back immediately, and the generator speed should return to below the lower limit of the wind turbine tower's resonance speed range. This will prevent the wind turbine from operating in the tower's resonance speed range for an extended period and reduce fatigue damage to the wind turbine tower.

[0046] Example 4 This embodiment further elaborates and supplements the implementation of the present invention based on Embodiment 3.

[0047] In this embodiment, step S23 involves iteratively calculating the theoretical wind speed based on the real-time operating data of the wind turbine and the power balance equation. In step S32, the theoretical wind speed is calculated iteratively based on the real-time operating data of the wind turbine and the power balance equation. The calculation method is the same, and the following method is used for calculation: In step S23, the theoretical wind speed is iteratively calculated based on the real-time operating data of the wind turbine and the power balance equation. In step S32, the theoretical wind speed is calculated iteratively based on the real-time operating data of the wind turbine and the power balance equation. The power balance equation is as follows: ; in: This refers to the actual air density, in kg / m³. Pi; The radius of the wind turbine is in meters (m). Wind speed, unit: m / s; Moment of inertia, unit: kg·m²; The angular velocity of the wind turbine, in rad / s; Angular acceleration of the wind turbine, unit: rad / s²; For the tip speed ratio, ; The pitch angle of the wind turbine blade; Tip speed ratio and propeller pitch angle The corresponding wind energy utilization coefficient can be determined by the tip speed ratio. and propeller pitch angle Look up the wind energy utilization coefficient table for wind turbine units using linear interpolation. Obtain Figure 5 The table shown is a wind energy utilization coefficient table for a certain wind turbine unit in this embodiment. Schematic diagram; For power loss; ,coefficient k Design parameters for wind turbine units.

[0048] like Figure 6 As shown, the theoretical wind speed is calculated iteratively based on real-time operating data of the wind turbine and the power balance equation. The steps are as follows: S231. Iterative calculation of theoretical wind speed initialization, the initialization content includes: setting the theoretical wind speed... Initialize to the current wind speed The calculated wind speed is the theoretical wind speed. The left side of the power balance equation is numerical Calculate the numerical values ​​on the right side of the power balance equation. Calculate the absolute value of the numerical difference between the left and right sides of the power balance equation. Determine the theoretical wind speed Iterative correction direction: if > Theoretical wind speed The iterative correction direction is negative; otherwise, the theoretical wind speed... The direction of iterative correction is positive; S232. Correct the theoretical wind speed according to the set step size. ; In step S232, the specific method is as follows: if the theoretical wind speed The direction of iterative correction is positive. If the theoretical wind speed The direction of iterative correction is negative. , To set the step size, in this embodiment, the step size is set to 0.1 m / s. The smaller the step size, the higher the theoretical wind speed obtained from the iterative calculation. The more accurate.

[0049] S233, Calculate theoretical wind speed The absolute value of the numerical difference between the left and right sides of the corresponding power balance equation ; In step S233, the calculation is as follows: The calculated wind speed is the theoretical wind speed. The values ​​on the left side of the power balance equation: ; Calculate the values ​​on the right side of the power balance equation: ; Calculate the absolute value of the numerical difference between the left and right sides of the power balance equation: .

[0050] S234. Determine whether the theoretical wind speed iterative calculation has ended. If the theoretical wind speed iterative calculation has ended, proceed to step S235. If the theoretical wind speed iterative calculation has not ended, proceed to step S232. In step S234, specifically: if > Then the theoretical wind speed iterative calculation ends, and the process moves to step S235. If < If the theoretical wind speed iterative calculation is not completed, then... Assigned value , ,Will Assigned value , Then proceed to step S232.

[0051] S235, Calculate theoretical wind speed ; In step S235, the calculation is as follows: .

[0052] The theoretical wind speed under start-up control state I can be obtained by following the above steps. Theoretical wind speed under start-up control state II .

Claims

1. A start-up control method for a wind turbine main control system, characterized in that: The start-up control is divided into four control states, including standby control state, start-up control state I, start-up control state II, and grid connection control state. In standby control mode, control the pitch to the standby pitch angle and obtain the average measured wind speed during standby control mode. And calculate the start-up wind speed Equivalent start-up wind speed based on actual air density When the average measured wind speed > Actual air density equivalent start-up wind speed And the duration exceeds the set value Switching from standby control state to power-on control state I; During startup control state I, the generator speed is controlled by pitch control to achieve the target generator speed for startup control state I. And calculate the average theoretical wind speed. ; When the average theoretical wind speed > Actual air density equivalent start-up wind speed And the duration exceeds the set value Switch from start-up control state I to start-up control state II; In start-up control state II, the generator speed changes from the target generator speed in start-up control state I. Towards grid connection speed Increase and calculate the average theoretical wind speed under start-up control state II. ; When the target generator speed reaches the grid connection speed Switch to grid-connected control mode; When the duration of start-up control state I exceeds the maximum allowable time of start-up control state I. The system switches from power-on control state I to standby control state. When the startup control state II runs Exceeding the maximum running time of Start-up Control State II Or the operating time within the resonant speed range of the wind turbine tower. Exceeding the maximum operating time within the resonant speed range of the wind turbine tower ,and <Actual air density equivalent start-up wind speed> Switch from start-up control state II to start-up control state I; The standby control state includes the following control steps: S11, control the pitch angle to the standby pitch angle; S12. Calculate the actual air density based on altitude and ambient temperature. ; S13. Based on actual air density Calculate start-up wind speed Equivalent start-up wind speed based on actual air density ; S14. State switching judgment in standby control mode: dynamically calculate and measure wind speed. Average measured wind speed within a set time window Determine whether the condition for switching from standby control state to start-up control state I is met. If it is met, switch the control state to start-up control state I; otherwise, repeat S12-S14. In step S13, the equivalent start-up wind speed based on the actual air density is calculated. as follows: ； in This is the actual air density. Start-up wind speed The corresponding air density.

2. The start-up control method of a wind turbine main control system as described in claim 1, characterized in that: In step S12, the actual air density is calculated. as follows: ； in: This is the standard atmospheric pressure at sea level, with a value of 101325 Pa. This is the temperature at sea level in the standard atmospheric pressure model, with a value of 288.15 K; This is the ambient temperature, expressed in °C. This refers to the altitude at the center of the wind turbine hub, measured in meters (m). It is the universal gas constant, with a value of 8.314 J / (mol·K); This is the molar mass of air, with a value of approximately 0.0289644 kg / mol; It is the vertical temperature lapse rate, with a value of approximately 0.0065 K / m; This is the acceleration due to gravity, with a value of approximately 9.8 m / s². 2 .

3. The start-up control method of a wind turbine main control system as described in claim 1 or 2, characterized in that: The startup control state I includes the following control steps: S21. Controlling generator speed via pitch control: Target speed is the generator speed under start-up control state I. ; S22. Theoretical wind speed calculation enable judgment: When the generator speed reaches the target generator speed under start-up control state I. Then, the theoretical wind speed calculation enable is set to 1 and kept at 1 under the start-up control state I. If the theoretical wind speed calculation enable is 1, proceed to step S23; otherwise, proceed to step S21. S23. Calculate the theoretical wind speed under start-up control state I iteratively based on the real-time operating data and power balance equation of the wind turbine. ; S24. State switching judgment under start-up control state I: Dynamic calculation of theoretical wind speed. Average theoretical wind speed within a set time window The running time of start-up control state I is counted, and it is determined whether the conditions for switching from start-up control state I to start-up control state II are met. If the conditions are met, the control state is switched to start-up control state II. If the conditions are not met, it is further determined whether the conditions for switching from start-up control state I to standby control state are met. If the conditions are met, the theoretical wind speed calculation enable is set to 0, and the control state is switched to standby control state. If the conditions are not met, the process proceeds to step S21.

4. The start-up control method of a wind turbine main control system as described in claim 3, characterized in that: The startup control state II includes the following control steps: S31. Controlling generator speed via pitch control: Target speed is the grid-connected speed. ; S32. Calculate the theoretical wind speed under start-up control state II based on real-time operating data and power balance equations of the wind turbine. v2 Theory ; S33. State switching judgment under start-up control state II: Dynamic calculation of theoretical wind speed. Average theoretical wind speed within a set time window Statistical analysis of the running time of start-up control state II Statistical analysis of the operating time within the resonant speed range of the wind turbine tower. Determine whether the conditions for switching from start-up control state II to grid-connected control state are met. If they are met, switch the control state to grid-connected control state. If not, further determine whether the conditions for switching from start-up control state II to start-up control state I are met. If they are met, switch the control state to start-up control state I. Otherwise, proceed to step S31.

5. The start-up control method of a wind turbine main control system as described in claim 4, characterized in that: In step S23, the theoretical wind speed is iteratively calculated based on the real-time operating data of the wind turbine and the power balance equation. In step S32, the theoretical wind speed is calculated iteratively based on the real-time operating data of the wind turbine and the power balance equation. The power balance equation is as follows: ； in: This refers to the actual air density, in kg / m³. Pi; The radius of the wind turbine is in meters (m). Wind speed, unit: m / s; Moment of inertia, unit: kg·m²; The angular velocity of the wind turbine, in rad / s; Angular acceleration of the wind turbine, unit: rad / s²; For the tip speed ratio, ; The pitch angle of the wind turbine blade; Tip speed ratio and propeller pitch angle The corresponding wind energy utilization coefficient; For power loss; ,coefficient k Design parameters for wind turbine units.

6. The start-up control method of a wind turbine main control system as described in claim 5, characterized in that: The theoretical wind speed is calculated iteratively based on real-time operating data of the wind turbine and the power balance equation. The steps are as follows: S231, Iterative calculation of theoretical wind speed initialization; S232. Correct the theoretical wind speed according to the set step size. ; S233, Calculate theoretical wind speed The absolute value of the numerical difference between the left and right sides of the corresponding power balance equation ; S234. Determine whether the theoretical wind speed iterative calculation has ended. If the theoretical wind speed iterative calculation has ended, proceed to step S235. If the theoretical wind speed iterative calculation has not ended, proceed to step S232. S235, Calculate theoretical wind speed .

7. The start-up control method of a wind turbine main control system as described in claim 6, characterized in that: In step S231, the initialization content includes: Theoretical wind speed Initialize to the current wind speed ; The calculated wind speed is the theoretical wind speed. The left side of the power balance equation is numerical ; Calculate the values ​​on the right side of the power balance equation. ; Calculate the absolute value of the numerical difference between the left and right sides of the power balance equation. ; Determine the theoretical wind speed Iterative correction direction: if > Theoretical wind speed The iterative correction direction is negative; otherwise, the theoretical wind speed... The direction of iterative correction is positive.

8. The start-up control method of a wind turbine main control system as described in claim 7, characterized in that: In step S232, the specific method is as follows: if the theoretical wind speed The direction of iterative correction is positive. If the theoretical wind speed The direction of iterative correction is negative. , To set the step size.

9. The start-up control method of a wind turbine main control system as described in claim 8, characterized in that: In step S233, the calculation is as follows: The calculated wind speed is the theoretical wind speed. The values ​​on the left side of the power balance equation: ； Calculate the values ​​on the right side of the power balance equation: ； Calculate the absolute value of the numerical difference between the left and right sides of the power balance equation: 。 10. The start-up control method of a wind turbine main control system as described in claim 9, characterized in that: In step S234, specifically: if > Then the theoretical wind speed iterative calculation ends, and the process moves to step S235. If < If the theoretical wind speed iterative calculation is not completed, then... Assigned value , ,Will Assigned value , Then proceed to step S232.

11. The start-up control method of a wind turbine main control system as described in claim 10, characterized in that: In step S235, the calculation is as follows: 。

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