Operation mode switching control method and device for offshore wind turbine generator

Abstract

The invention provides an operation mode switching control method and device for an offshore wind turbine generator, and relates to the technical field of wind turbine generator control, and the method comprises the steps: collecting operation parameters and environment parameters corresponding to key nodes of a unit in real time, constructing a unit operation state topological data set through space-time correlation coding, and storing the topological data set in a database; determining an environment mutation coefficient and a structure response index, calculating a comprehensive threat index, and triggering a mode switching signal when the threat index exceeds a preset threshold value; a transition control stage is set between a power generation mode and a shutdown mode, the initial power drop rate is determined through the rotating speed of a generator and the voltage of a direct-current bus, a yaw compensation item is calculated in combination with the wind direction change rate, the power drop rate is corrected, and power slope drop and active yaw control are achieved till the shutdown state is achieved; the environment and structure states are continuously monitored after stable shutdown, if the environment and structure states are recovered to be normal in continuous multiple periods, power output is gradually recovered to a rated value, and safe and efficient operation mode switching is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wind turbine control, in particular to a switching control method and device for operating modes of offshore wind turbines. BACKGROUND

[0002] In the southeast coastal sea area where typhoons are frequent, the operation of offshore wind turbines faces severe challenges. Every summer, this area often suffers from strong typhoon attacks, with wind speeds reaching more than 40 m / s, which poses a significant threat to the safe operation of wind turbines. At present, many offshore wind turbines adopt a semi-direct-drive medium-speed transmission structure and are equipped with full-power converters and active yaw systems to improve power generation efficiency and adaptability. However, the existing control strategy has obvious shortcomings in dealing with emergency shutdown during typhoons. Power grid operators usually require the unit to perform emergency shutdown before the typhoon arrives, but if the shutdown mode is switched too early, it will inevitably cause considerable economic losses to the generator, and if the switching time is too late, it may cause overvoltage of the converter DC bus due to sudden turbulence, increasing the risk of equipment damage. This operational contradiction reflects the limitations of the existing control strategy in dynamically responding to extreme weather conditions, which cannot guarantee safety while minimizing power generation losses.

[0003] In addition, after the typhoon passes, the restart timing in the wind speed recovery stage depends on a simple wind speed threshold, which has great uncertainty in actual operation. The traditional control strategy is prone to cause frequent start-stop of the unit under gust conditions, increasing the risk of mechanical wear and failure, and thus affecting the long-term stability and reliability of the unit. Lack of real-time monitoring and dynamic judgment of environmental changes makes the unit unable to flexibly respond to complex weather changes, affecting the overall operating efficiency. In order to effectively solve these problems, an intelligent control method that can comprehensively consider environmental changes, operating conditions and real-time data is urgently needed to achieve smooth transition of wind turbines in extreme weather conditions, ensuring the dual goals of safety and economic benefits.

[0004] The above information disclosed in the background section is only used to enhance the understanding of the background of the present disclosure, and therefore it can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0005] The purpose of the present application is to provide a switching control method and device for operating modes of offshore wind turbines to solve the problems raised in the background.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions: A switching control method for operating modes of offshore wind turbines, comprising the following specific steps: Step 1: Collect the operating parameters corresponding to different key nodes of the unit and the environmental parameters of the unit in real time, and construct a unit operating state topology dataset by time-space correlation coding with the node topology number as the index; the operating parameters include generator speed, DC bus voltage, and three-dimensional machine cabin vibration acceleration, and the environmental parameters include wind speed, wind direction, and turbulence intensity; Step 2: Based on the unit operating state topology dataset, determine the environmental mutation coefficient and the structure response index, calculate the comprehensive threat index according to the environmental mutation coefficient and the structure response index, and when the comprehensive threat index exceeds the preset mutation threshold, trigger the mode switching signal; Step 3: Based on the mode switching signal, insert a transition control phase between the power generation mode and the shutdown mode, and the execution logic is: first determine the initial power reduction rate based on the current generator speed and the DC bus voltage, and calculate the yaw compensation term according to the wind direction change rate, control the yaw system to perform active offset, modify the initial power reduction rate by the yaw compensation term to obtain the tuned reduction rate, and control the converter to perform power ramp-down at the rate until the shutdown state; Step 4: When the unit enters a stable shutdown state, continuously monitor the environmental mutation coefficient and the structure response index: if the environmental mutation coefficient and the structure response index are both within the normal range for 3 consecutive monitoring periods, start the soft start program, first restore the converter grid connection function, and then gradually increase the power output to the rated value.

[0007] Further, the specific execution process of step 1 is: The key nodes include the generator bearing seat, the converter DC bus terminal, and the machine cabin-tower flange of the unit, a sensing node is arranged at each key node, and the generator speed data is collected at the generator bearing seat, the DC bus voltage data is collected at the converter DC bus terminal, and the three-dimensional machine cabin vibration acceleration data is collected at the machine cabin-tower flange as the operating parameters of the unit; at the same time, the real-time wind speed, wind direction, and turbulence intensity are obtained through a wind speed measuring device as environmental parameters, wherein the wind speed measuring device includes an anemometer and a wind vane; each sensing node is assigned a unique topology number containing position coding and function identification, the operating parameters are bound with their topology number and time stamp, and data alignment and verification are performed according to the preset time-space correlation rule to construct a unit operating state topology dataset containing operating parameter values, spatial position, and time information; Wherein, the turbulence intensity is: the ratio of the standard deviation of the wind speed at the top of the cabin within the current 30s to the average wind speed within the last 10 minutes from the current time, which is used to quantify the instability of wind energy input.

[0008] Further, based on the unit operating state topology dataset, the environmental mutation coefficient and the structure response index are determined according to the following formula: wherein, is an environmental mutation coefficient, used to reflect the severity of wind speed and wind direction change, is the instantaneous wind speed at the current time, is the average wind speed in the last 10 minutes from the current time, is the wind direction change rate at the current time, is a wind direction sensitive coefficient, and is a structure response index, used to represent the abnormal state of the mechanical and electrical system of the unit, and respectively represent the three-dimensional nacelle vibration acceleration in the direction of the main shaft, the transverse direction and the vertical direction of the wind turbine at the current time, and and respectively represent the vibration acceleration threshold in the direction of the main shaft, the transverse direction and the vertical direction of the wind turbine, is the DC bus voltage at the current time, is the rated DC voltage, is a voltage influence factor, and is the generator speed at the current time, is the reference speed under the current working condition, is a speed sensitive coefficient, and wherein, the wind direction change rate is determined according to the wind direction data at the current time and the previous time, and the formula is as follows: wherein, is a correction function, refers to the wind direction data at the current time, refers to the wind direction data at the previous time, is the time interval between the current time and the previous time, is a sign function.

[0009] Further, the comprehensive threat index is calculated according to the environmental mutation coefficient and the structure response index, and the formula is as follows: wherein, is a comprehensive threat index, used to evaluate the overall risk level of the current unit, is an environmental mutation coefficient, is a structure response index, refers to the maximum value of and is used to make​​​​​​​​ always fall within the interval; and when the comprehensive threat index , trigger mode switching signal; wherein, is a preset mutation threshold, determined according to the type of the unit and the typhoon level.

[0010] Further, based on the current generator speed and the DC bus voltage, the initial power reduction rate is determined by table lookup method: ; In the formula, is the initial power reduction rate, is the rated power of the unit, is the DC bus voltage at the current time, is the rated DC voltage, is the generator speed at the current time, is the reference speed under the current working condition; The yaw compensation angle is calculated according to the wind direction change rate: ; In the formula, is the yaw compensation angle, is the wind direction change rate at the current time, is the response time of the yaw system; The initial power reduction rate is corrected by the yaw compensation angle to obtain the tuned reduction rate, according to the formula as follows: ; In the formula, is the tuned reduction rate; The converter is controlled to perform power ramp-down according to , and the yaw system is controlled to perform angle offset, and the offset direction is opposite to the wind direction change direction.

[0011] Further, the specific execution process of step 4 is as follows: when the unit enters a stable shutdown state, the environmental mutation coefficient and the structural response index are continuously monitored, and if the coefficient and the index are both lower than the respective safety threshold in the last 3 monitoring periods, the staged soft start program is started: first, the electrical connection between the converter and the power grid is restored and the zero power output is maintained, and after the electrical parameters are stable, the power output is gradually increased at a preset rate, while the unit state parameters are monitored in real time during the power increasing process, and if an abnormality is detected, the power increasing process is paused and the current operating state is maintained, until the unit state is stable again and the power is continued to be increased, and finally the unit is restored to rated power operation.

[0012] The application further provides a mode switching control device for an offshore wind turbine, which is used to execute the mode switching control method for the offshore wind turbine, and comprises: A multi-source data acquisition module is configured to acquire operation parameters corresponding to different key nodes of the unit and environment parameters of the unit in real time, and to construct a unit operation state topology data set by time-space correlation coding with the node topology number as an index; the operation parameters include generator speed, DC bus voltage and three-dimensional cabin vibration acceleration, and the environment parameters include wind speed, wind direction and turbulence intensity; A threat assessment decision module is configured to determine an environment mutation coefficient and a structure response index based on the unit operation state topology data set, to calculate a comprehensive threat index according to the environment mutation coefficient and the structure response index, and to trigger a mode switching signal when the comprehensive threat index exceeds a preset mutation threshold; A cooperative transition control module is configured to insert a transition control stage between the power generation mode and the shutdown mode based on the mode switching signal, and the execution logic is as follows: first, an initial power reduction rate is determined based on the current generator speed and the DC bus voltage, a yaw compensation term is calculated according to the wind direction change rate, the yaw system is controlled to perform active offset, the initial power reduction rate is modified by using the yaw compensation term to obtain a tuned reduction rate, and the converter is controlled to perform power ramp-down at the rate until the shutdown state; A safe re-grid module is configured to monitor the environment mutation coefficient and the structure response index continuously when the unit enters a stable shutdown state: if the environment mutation coefficient and the structure response index are both restored to the normal range in the last three monitoring periods, a soft start program is started, the converter grid connection function is restored first, and then the power output is gradually increased to the rated value.

[0013] Compared with the prior art, the application has the following beneficial effects: The application significantly improves the safety and reliability of unit operation under typhoon conditions through multi-dimensional state monitoring and intelligent decision mechanism. The scheme innovatively integrates the environment mutation characteristics and the structure dynamic response for fusion evaluation, realizes more accurate mode switching timing judgment, avoids the loss of power generation caused by premature shutdown and the equipment risk caused by late response. In the transition control stage, the power regulation and the yaw system are cooperatively operated to effectively suppress the electrical impact and mechanical vibration in the mode switching process, and ensure that the unit enters the shutdown state smoothly. At the same time, the intelligent re-grid strategy based on multi-parameter verification overcomes the defects of frequent start-stop of the traditional method under gust conditions, so that the unit can safely and stably restore power generation. The overall scheme optimizes the unit control strategy in the whole process of typhoon passage under the premise of ensuring the safety of the equipment, and provides an innovative solution for the reliable operation of offshore wind power under extreme weather conditions. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The whole method flowchart of the present application is shown in the figure. Figure 2 The whole device module of the present application is shown in the figure. Figure 3 、 Figure 4 The 3D scatter diagram and 3D columnar diagram of the environmental mutation coefficient, the structural response index and the comprehensive threat index are shown in the figures. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with specific embodiments.

[0016] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present application should be the commonly understood meanings by those skilled in the art to which the present application belongs. The "first", "second" and similar words used in the present application do not represent any order, quantity or importance, but are only used to distinguish different components. "Include" or "contain" and similar words mean that the elements or objects before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connected" or "connected" and similar words are not limited to physical or mechanical connection, but can include electrical connection, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to represent relative positional relationship, when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0017] Embodiment: Please refer to Figure 1 The present application provides a technical scheme: The operating mode switching control method of the offshore wind turbine, the specific steps include: Step 1: Real-time acquisition of operating parameters corresponding to different key nodes of the unit and environmental parameters of the unit, and construction of unit operating state topology data set through space-time correlation coding with node topology number as index; the operating parameters include generator speed, DC bus voltage, three-dimensional cabin vibration acceleration, and the environmental parameters include wind speed, wind direction and turbulence intensity; In this embodiment, the specific execution process of step 1 is: The key nodes include a generator bearing seat of a unit, a converter DC bus terminal and a nacelle-tower flange, a sensing node is arranged at each key node, generator rotating speed data are collected at the generator bearing seat, DC bus voltage data are collected at the converter DC bus terminal, and three-dimensional nacelle vibration acceleration data are collected at the nacelle-tower flange, as operating parameters of the unit; meanwhile, real-time wind speed, wind direction and turbulence intensity are obtained through a wind speed measuring device as environmental parameters, wherein the wind speed measuring device comprises an anemometer and a wind vane; each sensing node is assigned a unique topology number containing position coding and function identification, the operating parameters are bound with the topology number and a time stamp, data alignment and verification are performed according to a preset space-time correlation rule, and a unit operating state topology data set containing operating parameter values, spatial positions and time information is constructed; The turbulence intensity is a ratio of a wind speed standard deviation of a nacelle top within current 30s to an average wind speed within the nearest 10 minutes from the current moment, which is used to quantify instability of wind energy input.

[0018] Step 1 realizes effective organization and management of multi-node data by collecting operating parameters and environmental parameters of different key nodes of the unit in real time and constructing an operating state topology data set with node topology numbers as indexes. Through space-time correlation coding, time alignment, spatial position binding and abnormality checking are performed on the collected data, so that the integrity and consistency of the data are ensured, thereby providing a reliable basis for subsequent analysis. Compared with the traditional method, this step can more accurately capture the dynamic changes of the operating state of the unit and the influence of the environment on the unit, thereby laying a foundation for faster and more accurate mode switching decisions.

[0019] Compared with the prior art, the beneficial effects of step 1 are as follows: first, the operating state of the unit can be more accurately reflected by comprehensive collection of operating parameters of key nodes and quantitative monitoring of environmental parameters; second, the unified alignment of multi-node data and the processing of abnormal points are realized by using a space-time correlation rule, thereby improving the reliability and availability of the data; and third, the spatial position and time information are introduced into the data set to organize the data topologically, thereby supporting more complex state modeling and subsequent analysis. Overall, step 1 significantly improves the accuracy and real-time performance of wind turbine operating state perception.

[0020] In the present application, step 1 as a basic link of the scheme plays an important role in promoting the overall scheme. By constructing the operating state topology data set, high-quality data support is provided for accurate calculation of the environmental mutation coefficient and the structural response index, and dynamic coordination of multi-node and multi-parameter is realized, so that the triggering conditions of mode switching can be evaluated based on complete states. This step also provides reliable input parameters for the transition control phase, thereby enhancing the safety and accuracy of mode switching, and ensuring stable operation and efficient control of the generator unit in complex environments.

[0021] Step 2: Based on the unit operating state topology data set, determine the environmental mutation coefficient and the structure response index, calculate the comprehensive threat index according to the environmental mutation coefficient and the structure response index, and trigger the mode switching signal when the comprehensive threat index exceeds the preset mutation threshold; In this embodiment, based on the unit operating state topology data set, the environmental mutation coefficient and the structure response index are determined according to the following formula: ; In the formula, is the environmental mutation coefficient, which is used to reflect the intensity of wind speed and wind direction change, is the instantaneous wind speed at the current moment, is the average wind speed in the last 10 minutes from the current moment, is the wind direction change rate at the current moment, is the wind direction sensitive coefficient, and ; is the structure response index, which is used to represent the abnormal state of the mechanical and electrical system of the unit, 、 and respectively represent the three-dimensional nacelle vibration acceleration along the main shaft direction, the transverse direction and the vertical direction of the wind turbine at the current moment, and 、 and respectively represent the vibration acceleration threshold along the main shaft direction, the transverse direction and the vertical direction of the wind turbine, is the DC bus voltage at the current moment, is the rated DC voltage, is the voltage influence factor, and ; is the generator speed at the current moment, is the reference speed under the current working condition, is the speed sensitive coefficient, and ; The formula quantifies the relative intensity of wind speed fluctuation by multiplying the turbulence intensity and the instantaneous wind speed by the average wind speed, reflects the influence of wind direction mutation by combining the product of the wind direction sensitive coefficient and the absolute value of the wind direction change rate, and realizes the organic integration of wind speed and wind direction two types of environmental parameters in form. All parameters are in dimensionless or physical quantity ratio form, which ensures that environmental changes of different dimensions can be directly added and calculated, and the weight of the wind direction factor is adjusted by the positive coefficient , so that the formula can reflect the overall stability of wind energy input and highlight the threat of wind direction change, which conforms to the comprehensive evaluation logic of environmental mutation risk, and the calculation result can be directly used for subsequent threat index determination.

[0022] The formula for calculating the environmental mutation coefficient, the dependent variable is the environmental mutation coefficient , for reflecting the intensity of wind speed and wind direction change, the meaning is to quantify the stability of wind energy input and the risk of wind direction mutation. The technical effect is to realize the rapid identification of extreme wind conditions by fusing the ratio of turbulence intensity to instantaneous wind speed, wind direction change rate, to provide environmental level judgment basis for mode switching, and avoid frequent start and stop of the unit caused by single parameter misjudgment. The term reflects the amplitude of wind speed fluctuation, and the larger the ratio, the more severe the wind speed mutation; The term directly reflects the wind direction change speed, for amplifying the impact of wind direction mutation on , to ensure that significantly increases when the wind direction changes dramatically, therefore, and , are positively correlated.

[0023] For the calculation formula of the structure response index, the dependent variable is the structure response index , for representing the abnormal state of the mechanical and electrical system of the unit, the meaning is to quantify the degree of vibration, voltage and speed deviation from the normal range. The technical effect is to reflect the abnormality of the unit structure stress and electrical performance through multi-dimensional parameter fusion, avoid missing judgment when a single parameter exceeds the threshold, and provide equipment safety level judgment basis for mode switching. The vibration acceleration ratio term reflects the structure vibration overrun, and the voltage and speed deviation , reflects the stability of the electrical system, , is used to adjust the weight of the two types of deviation on . The formula uses the square root of the sum of the square of the three-dimensional vibration acceleration ratio to reflect the comprehensive overrun of the structure vibration, and the relative value of the voltage deviation and the speed deviation to reflect the abnormality of the electrical system, which realizes the cross-domain fusion of mechanical and electrical parameters in form. All deviation terms are expressed in relative value, eliminating the difference between different physical dimensions, and through the positive coefficient , flexibly adjust the weight of the two types of deviation, so that the formula can not only comprehensively cover the key state parameters of the unit, but also highlight the key attention items according to the characteristics of the equipment. The calculation result can objectively reflect the overall abnormality of the unit, and meet the quantitative demand of structure safety evaluation.

[0024] Wherein, the wind direction change rate is determined according to the wind direction data of the current time and the last time, and the formula is as follows: ; In the formula, is a correction function, wind direction data at the current moment, wind direction data at the last moment, is the time interval between the current moment and the last moment, is a sign function, used to determine the change direction of the wind direction between the current moment and the last moment, when the wind direction changes from to clockwise, when the wind direction changes from to counterclockwise, .

[0025] The comprehensive threat index is calculated according to the environmental mutation coefficient and the structural response index, and the formula is as follows: ; In the formula, is the comprehensive threat index, used to evaluate the overall risk level of the current unit, is the environmental mutation coefficient, is the structural response index, is the maximum value of and , used to make always fall within the interval ; and when the comprehensive threat index , a mode switching signal is triggered; wherein, is a preset mutation threshold, determined according to the type of the unit and the typhoon grade.

[0026] The dependent variable is the comprehensive threat index, used to evaluate the overall risk level of the current wind turbine. Its meaning is to consider the environmental mutation coefficient and the structural response index comprehensively, and through normalization processing, the risk assessment result is limited within the interval , so that the result has intuitive and comparable nature. When the comprehensive threat index exceeds the set threshold , a mode switching signal is triggered to protect the unit safety. Its technical effect is reflected in that it can effectively combine the dynamic characteristics of environmental changes and unit responses, timely judge and warn the overall risk of the unit operation state, and provide guidance for the safe and stable operation of the wind turbine; wherein the preset mutation threshold is set according to the comprehensive evaluation and determination of the type of the unit, the design safety margin and the typhoon grade of the region.

[0027] In the formula, the independent variables environmental mutation coefficient and structural response index reflect the corresponding state of the wind turbine operation environment and the unit itself response. Both of them together determine the dependent variable The magnitude of the coefficient of variation. Specifically, a larger environmental abrupt change coefficient indicates that drastic changes in the external environment pose a threat to the unit's operation; a larger structural response index reflects potential significant anomalies in the unit's mechanical or electrical systems. Multiplying these two values ​​and then normalizing them comprehensively reflects the combined impact of the external environment and the unit's response on the overall risk. The relationship between the independent and dependent variables indicates that... The change is a combined result of changes in the environmental mutation coefficient and the structural response index. The larger the environmental mutation coefficient and the structural response index, the higher the overall risk of the system. and , Both show a positive correlation; that is, when the environmental abrupt change coefficient or the structural response index increases, the comprehensive threat index increases. This will also increase, indicating that the current risk level of the unit has risen.

[0028] Table 1: Comprehensive Threat Index Statistics Table

[0029] Please see Figures 3-4 Analysis of the above 15 sets of data shows that the comprehensive threat index in this plan... It can effectively reflect the coupling effect between environmental abrupt changes and structural responses. Data analysis shows that the comprehensive threat index... It exhibits a unique "coupling amplification-normalization constraint" characteristic: when the environmental abrupt change coefficient... With structural response index When the increase is synchronous, such as in groups 3, 7, and 12, The value will quickly approach 1, accurately reflecting the combined effect of the double risk; while when and When the difference is significant, such as in group 5 , , The value will converge toward a smaller value, but through The product term retains the synergistic effect of both. This design avoids misjudgment caused by a sudden change in a single parameter, and also... The normalization process ensures the stability of the output value range, and this characteristic ensures the stability and reliability of risk assessment.

[0030] From the perspective of data distribution, The value exhibits a clear ability to differentiate operating conditions: in and Under normal operating conditions with relatively low loads, such as groups 1, 4, and 9, Maintain below 0.3; when any indicator enters the warning range, such as groups 2, 6, and 11, The value rises to the interval of 0.3-0.6; and in the extreme working condition of double risk superposition, such as groups 3, 7 and 12, The value will quickly climb to above 0.6. This nonlinear response characteristic makes the scheme not only timely capture the threat of a single risk source, but also accurately identify the composite risk, and has better risk identification accuracy and anti-interference ability than the traditional linear weighting method.

[0031] Step 2: The influence of the unit operation state and external environment change on the stability of the unit is comprehensively evaluated by calculating the environmental mutation coefficient and the structural response index based on the running state topology data set, and the comprehensive threat index is further calculated as the core criterion for triggering mode switching, which improves the scientificity and accuracy of mode switching. Compared with the single monitoring parameter or the mode switching method based on experience, step 2 can realize multi-dimensional and multi-parameter comprehensive analysis, fully capture the coupling relationship between environmental change and internal response of the unit, and provide quantitative and accurate evaluation basis for mode switching.

[0032] Compared with the prior art, the beneficial effects of step 2 are: first, the introduction of the environmental mutation coefficient can effectively quantify the disturbance degree of the complex environment on the unit operation; second, the calculation of the structural response index accurately reflects the health status of the mechanical and electrical systems of the unit; third, the use of the comprehensive threat index normalizes the data of different dimensions and forms a unified mode switching criterion, making the mode switching more sensitive and reliable. Overall, step 2 significantly improves the accuracy and timeliness of the triggering of the mode switching signal.

[0033] In the present application, step 2 is the key link to realize the core logic of mode switching. Through the calculation of the environmental mutation coefficient and the structural response index, the dynamic changes of the external environment and the unit response can be captured in real time, providing a scientific basis for the triggering of the mode switching signal. At the same time, the introduction of the comprehensive threat index effectively solves the quantification problem of the complex coupling relationship of multiple parameters, making the mode switching more intelligent. This step provides an accurate triggering condition for the subsequent transition control phase, ensuring the timeliness and safety of mode switching, thereby ensuring the stable operation of the unit in harsh environments.

[0034] Step 3: Based on the mode switching signal, a transition control phase is inserted between the power generation mode and the shutdown mode, and the execution logic is: first, determine the initial power reduction rate based on the current generator speed and DC bus voltage, and calculate the yaw compensation term according to the wind direction change rate, control the yaw system to perform active offset, use the yaw compensation term to modify the initial power reduction rate to obtain the tuned reduction rate, and control the converter to perform power ramp-down at the rate until the shutdown state; In this embodiment, based on the current generator speed and DC bus voltage, the initial power reduction rate is determined by table lookup method: ; wherein, is the initial power reduction rate, is the unit rated power, is the DC bus voltage at the current moment, is the rated DC voltage, is the generator speed at the current moment, is the reference speed under the current operating condition; The formula defines the initial power reduction rate by the deviation degree of the generator speed and the DC bus voltage, and is associated with the unit rated power, which is reasonable in form and has physical meaning. The formula sets a detailed power reduction rate according to different conditions: when the speed significantly exceeds the reference value and the voltage deviation is large, a high rate is selected to quickly respond and protect the unit; when the speed or voltage deviation is small, the power reduction rate is reduced to to reduce unnecessary power regulation; in other operating conditions, the lowest reduction rate is set to maintain the basic protection mechanism. This segmented mode dynamically adjusts the power reduction rate according to the risk level of the unit operating state, which is clear in form, and ensures the safety of the unit while considering the operating efficiency.

[0035] Calculate the yaw compensation angle according to the wind direction change rate : ; wherein, is the yaw compensation angle, is the wind direction change rate at the current moment, is the yaw system response time; The dependent variable is the yaw compensation angle, which is used to adjust the yaw system of the wind turbine to adapt to the change of wind direction. Its meaning is to dynamically calculate the required angle compensation according to the wind direction change rate and the yaw system response time , and limit its maximum value to to avoid excessive yawing causing damage to the system. The technical effect lies in the ability to quickly respond to rapid changes in wind direction and improve wind capture efficiency, while limiting the compensation angle to balance the response speed and the operating life of the system. The wind direction change rate directly determines the urgency of yaw adjustment, the faster the change, the larger the required compensation angle; the yaw system response time determines the reaction ability of the yaw action, the longer the response time, the larger the required compensation angle. The dependent variable is the comprehensive result of the two, which reflects the specific yaw demand of the system under different wind direction change conditions.

[0036] The initial power reduction rate is corrected by the yaw compensation angle to obtain the tuned reduction rate, and the formula followed is as follows: ; In the formula, is the tuning drop rate; the control converter executes power ramp-down while controlling the yaw system to execute angular offset in the opposite direction of the wind direction change.

[0037] the dependent variable is the tuning drop rate, reflecting the result of modifying the initial power drop rate after considering the yaw compensation angle . The meaning is that by introducing the yaw compensation angle, the power drop rate is dynamically adjusted to make the power drop more accurately adapt to the current wind direction change and operating state of the unit. The technical effect is reflected in that when the yaw angle is large, the power drop rate is moderately reduced to avoid excessive response to the unit operation; and when the yaw angle is small, the power drop rate adjustment amplitude is reduced to ensure that the unit quickly responds to abnormal situations, thereby effectively improving the operation stability and efficiency.

[0038] The yaw state directly reflects the ability of the fan to track the wind direction and the severity of the wind direction change. When the yaw compensation angle increases, it means that the wind direction changes greatly or the fan is not fully aligned with the wind direction. At this time, the power drop rate is adjusted by the formula to reduce the amplitude of the power drop to avoid the power from dropping too fast due to the direction deviation or wind direction fluctuation. The introduction of the independent variable allows the drop rate to consider the influence of the yaw angle on power regulation, reflecting the dynamic characteristics of the fan operation. The dependent variable is negatively correlated with the independent variable . The larger the yaw compensation angle, the more severe the wind direction change, and the power drop rate will decrease accordingly, i.e., the drop amplitude is slower to avoid excessive power regulation caused by severe wind direction fluctuations; on the contrary, when is small, the tuning drop rate is closer to the initial value , maintaining a high response speed to balance the efficiency of power regulation and the stability of system protection. The design of in the formula reasonably limits the adjustment range of the tuning drop rate, ensuring the appropriateness and safety of the system response.

[0039] ​Step 3 realizes a smooth transition between the power generation mode and the shutdown mode by introducing a transition control stage, avoiding mechanical impact or electrical system instability problems that may be caused by direct switching of the wind turbine. By determining the initial power reduction rate based on the generator speed and the DC bus voltage, and combining the yaw compensation term calculated dynamically based on the change of wind direction, the power reduction rate is optimized, thereby realizing the synergistic effect of power ramp-down and active yaw control, making the unit operation more stable. At the same time, this step solves the problem of the unit's response not being timely in the case of rapid changes in wind speed and direction, enhancing the unit's adaptability to complex environments.

[0040] Compared with the prior art, the beneficial effects of step 3 are as follows: first, by introducing the design of tuning the reduction rate, the power reduction rate can be accurately adjusted according to the real-time operating state, reducing the impact of unit load changes on the power grid; second, through dynamic calculation of the yaw compensation angle and active yaw control, the unit can quickly adapt to changes in wind direction, reducing the loss of wind energy utilization efficiency; third, through the linkage control of power and yaw, the load fluctuation of mechanical structure and electrical system is minimized, thereby prolonging the service life of key components. Overall, step 3 greatly improves the safety and stability of the mode switching process.

[0041] In the present application, step 3 as the core execution link of the operation mode switching plays a crucial role in promoting the overall scheme. By designing a transition control stage, the problem of severe fluctuations that may occur in the direct switching process is solved, effectively ensuring the continuity and safety of the unit operation. At the same time, this step combines power control with yaw control, fully considering the dynamic change characteristics of environmental parameters and the real-time response of the unit operating state, making the mode switching process smoother and more intelligent. Finally, this step provides technical support for the efficient switching of the unit from the power generation mode to the shutdown mode, improving the applicability and reliability of the scheme.

[0042] Step 4: When the unit enters a stable shutdown state, continuously monitor the environmental mutation coefficient and the structure response index: if the environmental mutation coefficient and the structure response index are both within the normal range for 3 consecutive monitoring periods, start the soft start program, first restore the grid-connected function of the converter, and then gradually increase the power output to the rated value; In this embodiment, the specific implementation process of step 4 is as follows: when the unit enters a stable shutdown state, the environmental mutation coefficient and the structural response index are continuously monitored. If the coefficient and the index are both lower than the respective safety threshold in the last 3 monitoring periods, a staged soft start program is started: first, the electrical connection between the converter and the power grid is restored and zero power output is maintained. After the electrical parameters are stable, the power output is gradually increased at a preset rate. At the same time, the unit state parameters are monitored in real time during the power increasing process. If an abnormality is detected, the power increasing process is paused and the current operating state is maintained. After the unit state is stable again, the power is continued to be increased until the unit is restored to rated power operation.

[0043] The monitoring period is set to 5-10 minutes, and the specific duration is dynamically adjusted according to the rated power of the unit and the turbulence intensity of the sea environment: the higher the rated power and the higher the turbulence intensity, the shorter the period. This setting can accurately determine the stability of the environment and the unit state, and can avoid false start caused by too short period or power generation loss caused by too long period.

[0044] When the unit enters a stable shutdown state, the control system starts a continuous monitoring mechanism, with a monitoring period of 5-10 minutes. The changes of the environmental mutation coefficient and the structural response index are tracked in real time. If the coefficient and the index are always lower than the environmental safety threshold and the structural safety threshold in the last 3 monitoring periods, it is determined that the external environment and the unit state meet the restart conditions, and a staged soft start program is started immediately: first, the electrical connection between the converter and the power grid is re-established, and the zero power output state is maintained. The electrical parameters such as power grid voltage, frequency and converter DC side voltage are continuously monitored. When the fluctuation amplitudes of all indicators are less than the rated value and stable for more than 30 seconds, the power output is gradually increased at a preset rate of times rated power / minute. During the power increasing process, the generator speed, three-dimensional cabin vibration acceleration, DC bus voltage and other state parameters are collected synchronously. If any parameter exceeds the preset safety range, the power increasing is immediately paused and the current output state is maintained. After the parameter returns to normal and is stable for 1 minute, the power is continued to be increased at the original rate. Finally, the unit is smoothly transitioned to the rated power operating state.

[0045] Step 4 realizes dynamic evaluation of the external environment and operating state during the unit shutdown state by continuously monitoring the environmental mutation coefficient and the structural response index, and after the conditions return to the normal range, a phased soft start program is used to gradually restore the unit operating state. This phased recovery method avoids mechanical impact and electrical system instability problems that may be caused by direct and rapid start-up of the unit from the shutdown state, ensuring the smoothness and safety of the start-up process. At the same time, the real-time monitoring and anomaly detection mechanism makes the soft start process more adaptable and robust.

[0046] Compared with the prior art, the beneficial effects of Step 4 are: first, through multi-cycle verification of the safety threshold, the possibility of frequent switching due to short-term environmental fluctuations is reduced, and the stability of mode switching is improved; second, the phased soft start program effectively reduces the stress burden on electrical and mechanical systems, prolonging the service life of key components; third, through real-time monitoring and abnormal pause mechanism during the power-up process, the safety and reliability of the unit are further ensured. Overall, this step significantly optimizes the recovery process after shutdown, making the unit run more smoothly and efficiently.

[0047] In the present application, Step 4 is a key link for the unit to recover from shutdown mode to power generation mode, playing an important role in promoting the overall scheme. By continuously monitoring the environment and unit state, the scientificity and safety of the recovery process are ensured; by using a phased soft start program, the unit power output is smoothly increased, avoiding the impact and failure risks that may occur during mode switching. This step works in conjunction with the previous steps to build a complete mode switching control closed-loop mechanism, significantly improving the applicability and reliability of the scheme in complex offshore environments.

[0048] Please refer to Figure 2 , the operation mode switching control device of the offshore wind turbine, comprising: A multi-source data acquisition module for real-time acquisition of operating parameters corresponding to different key nodes of the unit and environmental parameters of the unit, and for constructing a unit operating state topology dataset through time and space correlation coding with node topology numbers as indexes; the operating parameters include generator speed, DC bus voltage, and three-dimensional machine cabin vibration acceleration, and the environmental parameters include wind speed, wind direction, and turbulence intensity; A threat assessment decision module for determining the environmental mutation coefficient and the structural response index based on the unit operating state topology dataset, calculating the comprehensive threat index according to the environmental mutation coefficient and the structural response index, and triggering a mode switching signal when the comprehensive threat index exceeds a preset mutation threshold; The cooperative transition control module is configured to insert a transition control stage between the power generation mode and the shutdown mode based on the mode switching signal, and the execution logic is as follows: firstly, an initial power reduction rate is determined based on the current generator speed and the DC bus voltage, and a yaw compensation term is calculated according to the wind direction change rate, the active yaw system is controlled to perform active yawing, the initial power reduction rate is modified by the yaw compensation term to obtain a tuned reduction rate, and the converter is controlled to perform power ramp-down at the rate until the shutdown state. The safe re-grid module is configured to monitor the environmental mutation coefficient and the structure response index when the unit enters the stable shutdown state, and if the environmental mutation coefficient and the structure response index are both restored to the normal range in the next 3 monitoring cycles, the soft start program is started, the converter grid connection function is restored first, and then the power output is gradually increased to the rated value.

[0049] The above formulas are dimensionless values calculated, the formulas are obtained by collecting a large amount of data to simulate the latest real situation, and the preset parameters in the formulas are set by a person skilled in the art according to the actual situation.

[0050] The above embodiments can be realized wholly or partially by software, hardware, firmware or any combination thereof. When realized by software, the above embodiments can be realized in the form of a computer program product wholly or partially. Those skilled in the art can realize that the units and algorithm steps of the examples described in connection with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized by hardware or software methods depends on the specific application and design constraints of the technical solutions.

[0051] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, which can be located in one place or distributed on multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0052] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for switching operating modes of offshore wind turbines, characterized in that, The specific steps include: Step 1: Real-time acquisition of operating parameters and environmental parameters of different key nodes of the unit, and construction of unit operating status topology dataset through spatiotemporal correlation coding using node topology number as index; the operating parameters include generator speed, DC bus voltage, and three-dimensional nacelle vibration acceleration, and the environmental parameters include wind speed, wind direction, and turbulence intensity; Step 2: Based on the unit operating status topology dataset, determine the environmental mutation coefficient and structural response index, calculate the comprehensive threat index based on the environmental mutation coefficient and structural response index, and trigger a mode switching signal when the comprehensive threat index exceeds the preset mutation threshold; Step 3: Based on the mode switching signal, a transition control phase is inserted between the generation mode and the shutdown mode. The execution logic is as follows: First, the initial power reduction rate is determined based on the current generator speed and DC bus voltage. At the same time, the yaw compensation term is calculated according to the wind direction change rate. The yaw system is controlled to perform active offset. The initial power reduction rate is corrected using the yaw compensation term to obtain the tuned reduction rate. The converter is then controlled to perform power ramp-down at this rate until the shutdown state is reached. Step 4: After the unit enters a stable shutdown state, continuously monitor the environmental mutation coefficient and structural response index: If the environmental mutation coefficient and structural response index return to the normal range within 3 consecutive monitoring cycles, start the soft start procedure, first restore the grid connection function of the converter, and then gradually increase the power output to the rated value.

2. The method for switching operating modes of offshore wind turbines according to claim 1, characterized in that: The specific execution process of step 1 is as follows: The key nodes include the generator bearing housing, the converter DC bus terminal, and the nacelle-tower connection flange of the unit. Sensing nodes are installed at each key node. Generator speed data is collected at the generator bearing housing, DC bus voltage data is collected at the converter DC bus terminal, and three-dimensional nacelle vibration acceleration data is collected at the nacelle-tower connection flange, serving as the unit's operating parameters. Simultaneously, real-time wind speed, wind direction, and turbulence intensity are acquired as environmental parameters through an anemometer and wind vane. Each sensing node is assigned a unique topology number containing a location code and a function identifier. After binding the operating parameters to their topology numbers and timestamps, data alignment and verification are performed according to preset spatiotemporal association rules to construct a unit operating status topology dataset containing operating parameter values, spatial location, and time information. The turbulence intensity is defined as the ratio of the standard deviation of the wind speed at the top of the nacelle within the current 30 seconds to the average wind speed within the most recent 10 minutes, which is used to quantify the instability of wind energy input.

3. The method for switching operating modes of offshore wind turbines according to claim 1, characterized in that: Based on the aforementioned unit operating status topology dataset, the environmental mutation coefficient and structural response index are determined using the following formulas: ； In the formula, This is the environmental abrupt change coefficient, used to reflect the drastic nature of changes in wind speed and direction. The instantaneous wind speed at the current moment. The average wind speed over the most recent 10 minutes. The rate of change of wind direction at the current moment. It is a wind direction sensitivity coefficient, and ; The structural response index is used to characterize abnormal states of the unit's mechanical and electrical systems. , and These represent the three-dimensional nacelle vibration accelerations along the main shaft, lateral direction, and vertical direction of the wind turbine at the current moment, respectively. , and These represent the vibration acceleration thresholds along the main shaft direction, the lateral direction, and the vertical direction of the wind turbine, respectively. The DC bus voltage at the current moment. This is the rated DC voltage. It is a voltage influence factor, and ; The generator speed at the current moment. This is the reference speed under the current operating conditions. It is the speed sensitivity coefficient, and ; The wind direction change rate is determined based on the wind direction data of the current moment and the previous moment, using the following formula: ； In the formula, For the correction function, This refers to the wind direction data at the current moment. Refers to the wind direction data at the previous moment. This represents the time interval between the current moment and the previous moment. It is a symbolic function.

4. The method for switching operating modes of offshore wind turbines according to claim 3, characterized in that: The comprehensive threat index is calculated based on the environmental abrupt change coefficient and the structural response index, using the following formula: ； In the formula, The comprehensive threat index is used to assess the overall risk level currently faced by the unit. The environmental mutation coefficient, The structural response index. finger take and The maximum value in is used to make Always fall Within the range; And when the comprehensive threat index When this occurs, a mode switching signal is triggered; in, The preset mutation threshold is determined based on the unit type and typhoon level.

5. The method for switching operating modes of offshore wind turbines according to claim 1, characterized in that: Based on the current generator speed and DC bus voltage, the initial power reduction rate is determined using a lookup table method: ； In the formula, The initial power decrease rate, The rated power of the unit, The DC bus voltage at the current moment. The rated DC voltage, The generator speed at the current moment. This is the reference speed under the current operating conditions; Calculate the yaw compensation angle based on the wind direction change rate. : ； In the formula, For yaw compensation angle, The rate of change of wind direction at the current moment. This refers to the yaw system response time. The initial power drop rate is corrected using the yaw compensation angle to obtain the tuned power drop rate, based on the following formula: ； In the formula, To tune the descent rate; Control converter according to The power ramp is reduced while the yaw system is controlled. The angle shifts, and the direction of the shift is opposite to the direction of the wind change.

6. The method for switching operating modes of offshore wind turbines according to claim 1, characterized in that: The specific execution process of step 4 is as follows: After the unit enters a stable shutdown state, the environmental mutation coefficient and structural response index are continuously monitored. If the coefficient and index are both lower than their respective safety thresholds within three consecutive monitoring cycles, a phased soft start procedure is initiated: First, the electrical connection between the converter and the grid is restored and zero power output is maintained. After the electrical parameters stabilize, the power output is gradually increased at a preset rate. At the same time, the unit status parameters are monitored in real time during the power increase process. If an abnormality is detected, the power increase process is paused and the current operating state is maintained until the unit status stabilizes again and the power is increased again, so that the unit can finally be restored to rated power operation.

7. An operating mode switching control device for offshore wind turbines, characterized in that: The aforementioned offshore wind turbine operation mode switching control device is used to execute the offshore wind turbine operation mode switching control method according to any one of claims 1-6, comprising: The multi-source data acquisition module is used to collect the operating parameters and environmental parameters of different key nodes of the unit in real time, and construct the unit operating status topology dataset by using the node topology number as an index and spatiotemporal correlation coding; the operating parameters include generator speed, DC bus voltage, and three-dimensional nacelle vibration acceleration, and the environmental parameters include wind speed, wind direction, and turbulence intensity. The threat assessment and decision-making module is used to determine the environmental mutation coefficient and structural response index based on the unit's operating status topology dataset, calculate the comprehensive threat index based on the environmental mutation coefficient and structural response index, and trigger a mode switching signal when the comprehensive threat index exceeds a preset mutation threshold. The collaborative transition control module is used to insert a transition control phase between the power generation mode and the shutdown mode based on the mode switching signal. Its execution logic is as follows: First, the initial power reduction rate is determined based on the current generator speed and DC bus voltage. At the same time, the yaw compensation term is calculated according to the wind direction change rate. The yaw system is controlled to perform active offset. The initial power reduction rate is corrected using the yaw compensation term to obtain the tuned reduction rate. The converter is then controlled to perform power ramp-down at this rate until the shutdown state is reached. The safe reconnection module is used to continuously monitor the environmental mutation coefficient and structural response index after the unit enters a stable shutdown state. If the environmental mutation coefficient and structural response index return to the normal range within three consecutive monitoring cycles, the soft start program is started to restore the grid connection function of the converter first, and then gradually increase the power output to the rated value.

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