A rotor aerodynamic coordination system for side-by-side multi-rotor offshore floating wind turbines

Abstract

The present application relates to side-by-side multi-rotor offshore floating wind turbine rotor aerodynamic coordination system, the system includes: wind speed-wind direction measuring module, for collecting wind speed-wind direction of the whole wind turbine and local wind speed-wind direction of each rotor, obtains first monitoring data;Rotor power generation state monitoring module, for collecting the rotor speed of the main shaft or the shaft end of the generator, and monitoring the power generation, obtaining second monitoring data;Central control module, for judging the wind turbine operating state through the first monitoring data and the second monitoring data, obtaining the judgment result, selecting the corresponding control mode according to the judgment result, distributing the aerodynamic power or the thrust sub-target for each rotor, generating the rotor speed and the pitch angle instruction signal of each rotor;Rotor aerodynamic adjustment execution module, for independently adjusting the main shaft speed and blade pitch angle of each rotor according to the instruction signal. The present application effectively improves the aerodynamic coordination, power generation efficiency and structural safety of multi-rotor floating wind turbine under full working condition.

Description

Technical Field

[0001] This invention relates to the field of wind power generation equipment and intelligent control technology, and in particular to a rotor aerodynamic coordination system and method for parallel multi-rotor offshore floating wind turbines. Background Technology

[0002] Offshore wind energy development is an important direction for new energy development. Floating offshore wind turbines are suitable for deployment in deep-sea areas and are a key technology for developing deep-sea wind energy. With the increasing capacity of individual wind turbines, the increase in single-unit power faces challenges in the manufacturing, transportation, installation, and reliability of ultra-large blades. Integrating multiple mature small-capacity wind turbine rotors side-by-side on the same support structure has become a promising solution, which is expected to reduce the technical risks and costs associated with giant blades. However, this type of parallel multi-rotor floating wind turbine faces unique technical challenges: First, the spatial inhomogeneity of the wind field (including wind shear and turbulence) leads to differences in the inflow conditions of the parallel-arranged rotors, causing uneven aerodynamic loads. Second, the six-degree-of-freedom motion (especially swaying and pitching) of the floating platform under the combined action of wind, waves, and current dynamically changes the actual inflow angle of attack and wind speed of each rotor, introducing additional aerodynamic load fluctuations and creating complex coupling with the rotor's aerodynamic response. Third, the aerodynamic thrust generated by multiple rotors acts on the same support structure, and the differences between them create unbalanced bending moments, significantly increasing the fatigue load on key structures such as the tower. In addition, when the prevailing wind direction changes, the multi-rotor system, due to its large inertia, results in a slow response compared to traditional tower top or single-point mooring yaw systems, which may lead to inaccurate wind alignment and decreased aerodynamic efficiency.

[0003] Currently, mature aerodynamic control schemes exist for traditional single-rotor floating wind turbines. However, for parallel multi-rotor floating wind turbines, there is still a lack of mature and effective collaborative control systems and methods to coordinate the aerodynamic behavior of multiple rotors and achieve system-level power optimization, load balancing, and motion-assisted control. Existing technologies struggle to address the aerodynamic performance mismatch between rotors caused by differences in wind field spatial distribution and platform motion coupling effects, which poses a bottleneck for the engineering application of parallel multi-rotor floating wind turbines.

[0004] Therefore, there is an urgent need for an intelligent control system that can actively coordinate the aerodynamic behavior of each rotor and optimize the overall performance of the system. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention aims to provide a rotor aerodynamic coordination system for parallel multi-rotor offshore floating wind turbines, which aims to improve the system response, power generation efficiency and structural safety of multi-rotor floating wind turbines under all life cycle operating conditions. At the same time, through a two-layer nested collaborative control mechanism, it achieves active balancing of the total system load and optimization of the total system power, and provides aerodynamic assistance for yaw motion.

[0006] To achieve the above objectives, the present invention provides the following solution: A parallel multi-rotor offshore floating wind turbine rotor aerodynamic coordination system includes: The wind speed-direction measurement module is used to collect the wind speed-direction of the entire wind turbine and the local wind speed-direction of each rotor to obtain the first monitoring data. The rotor power generation status monitoring module is used to collect the rotor speed at the main shaft or generator shaft end, monitor the power generation, and obtain secondary monitoring data. The central control module is used to determine the operating status of the wind turbine through the first monitoring data and the second monitoring data, obtain the judgment result, select the corresponding control mode according to the judgment result, allocate aerodynamic power or thrust sub-targets to each rotor, and generate command signals for the rotational speed and pitch angle of each rotor. The rotor pneumatic adjustment actuator module is used to independently adjust the main shaft speed and blade pitch angle of each rotor according to the command signal.

[0007] Optionally, the central control module includes: The outer coordinator is used to determine the operating status of the wind turbine through the first monitoring data and the second monitoring data, select the corresponding control mode, and allocate sub-targets of aerodynamic power or thrust to each rotor. The inner controller, used by the generator torque control device and the unified pitch control device based on the PID algorithm, generates command signals for the rotational speed and pitch angle of each rotor as setpoints from the sub-targets.

[0008] Optionally, the outer coordinator includes: The status judgment unit is used to judge the operating status of the fan through the first monitoring data and the second monitoring data, and obtain the judgment result. The judgment result includes: the fan is operating normally and the space wind speed uniformity is good, the fan is operating normally but the space wind speed uniformity is poor, there is a partial rotor fault, all rotor faults, and the fan is operating normally but the wind direction is off.

[0009] Optionally, the outer coordinator further includes: The mode control unit is used to select the corresponding control mode based on the judgment result. That is, when the wind speed is uniformly distributed in space and the rotor is normal, each rotor is controlled independently and the inner control loop is activated. That is, a proportional-derivative control model is used to control the pitch angle of each rotor based on the shaft speed signal. When the wind turbine is operating normally but the uniformity of the wind speed in space is poor, the rotor with the lower wind speed is adjusted to a smaller pitch angle, while the rotor with the higher wind speed is adjusted to a larger pitch angle, until the aerodynamic thrust of each rotor is consistent. When the wind turbine is operating normally but the wind direction is biased, the rotor located downstream of the wind direction is adjusted to a larger pitch angle, while the rotor located upstream of the wind direction is adjusted to a smaller pitch angle, so as to generate a torque for rotating around the yaw axis, until the deviation angle of the wind is eliminated. When a partial rotor failure occurs, the power output of the remaining normal rotors is re-optimized with the goal of load balance. That is, the aerodynamic thrust of the remaining normal rotors on the faulty side is increased, and the aerodynamic thrust of the normal rotors on the other side of the fault is decreased, so that the total aerodynamic thrust on both sides is consistent to maintain the load balance of the wind turbine system. When all rotor failures occur, the faulty rotor is instructed to feather and stop.

[0010] Optionally, the outer coordinator further includes: The first target allocation unit is used to allocate aerodynamic power or thrust sub-targets to each rotor based on the selected control mode. That is, when the wind speed spatial distribution is uniform and the rotors are normal, each rotor operates independently, and the reference value of the inner control loop is set to the rated optimal value without additional intervention. P ref,i =P max ; Δβref,i =0, ∀ i ∈{1,…,N}; in, Pref,i The target power setpoints allocated to each rotor by the outer controller. Pmax This represents the maximum power that the rotor can actually achieve. Δβref,i The first layer allocated to the outer controller i The pitch angle compensation value for each rotor. i The rotor sequence is N, and the total number of rotors is N. When the fan is operating normally but the airflow uniformity in the space is poor, the control objective is to minimize the aerodynamic thrust difference between the rotors to balance the platform load. That is, a thrust balance objective function is defined, and the thrust target value of each rotor is solved: in, , The objective function for rotor thrust balance is... Let be the aerodynamic thrust value of the i-th rotor. This represents the average rotor aerodynamic thrust value. Further, based on the approximate relationship between aerodynamic thrust and wind speed and pitch angle, a pitch angle compensation command is output to adjust the thrust. Δβref,i=Kbal⋅( ) In the formula, K bal Δβ is the balance gain coefficient. ref,i This is the pitch angle compensation value for the i-th rotor. Let be the inflow velocity of the i-th rotor. The average inflow velocity of the rotor; When the wind turbine is operating normally but the wind direction is off, the control objective is to generate a corrective torque to eliminate the wind deviation angle, that is, to calculate the required corrective torque command based on the wind deviation: Mcmd=Kp_yaw⋅ +Kd_yaw⋅ ; Among them, M cmd To correct the course torque for the target, For the wind deviation angle, K p_yaw K is the proportionality coefficient. d_yaw The differential coefficients are... t For time; further, differentiated thrust commands are allocated based on the spatial azimuth angle of each rotor to generate the torque: Db ref,i =−K yaw ⋅ M cmd ⋅sgn( r i ⋅n wind ); In the formula, ri is the th i The position vector of each rotor nwind This is a unit vector representing wind direction. Δβref,i For the first i The pitch angle compensation value for each rotor, Kyaw is the yaw control coefficient, and sgn is the sign function; When the aforementioned local rotor fault occurs, the control objective is to minimize the unbalanced torque, i.e., to recalculate the thrust distribution: ; in, For normal rotor assembly, For the set of faulty rotors, For the first i The position vector of each rotor For the first j The position vector of each rotor Furthermore, the normal rotor located on the side of the faulty rotor needs to have its aerodynamic thrust increased, while the normal rotor on the other side needs to have its thrust reduced: P ref,i = P opt,i + ΔP comp,i ,i ∈ Oh normal ; In the formula, ΔPcomp,i is the power compensation term. Pref,i The target power setpoints allocated to each rotor by the outer controller. Popt,i The optimal power for the rotor; When the aforementioned local rotor fault occurs, the safety protection mechanism is triggered, and a feathering shutdown command is issued to all rotors: β ref,i = β feather , T brake,i =1, ∀ i ∈{1,…,N}; in, βref,i For the first i The pitch angle of each rotor, bfeather This is the feathering angle, typically 90°. Tbrake This is a braking command.

[0011] Optionally, the inner controller includes: The second target allocation unit is used to determine whether a normally operating wind turbine is below its rated operating condition. When the normally operating wind turbine is below its rated operating condition, the target is to maintain the optimal tip speed ratio of the wind turbine and maximize wind energy capture efficiency. The generator torque control device is the primary unit, and the unified pitch control device is the secondary unit. The sub-target is used as the set value to generate command signals for the rotational speed and pitch angle of each rotor. When the normally operating wind turbine is above its rated operating condition, the target is to constrain and stabilize the generator speed and power. The unified pitch angle control device is the primary unit, and the generator torque control device is the secondary unit. The sub-target is used as the set value to generate command signals for the rotational speed and pitch angle of each rotor.

[0012] Optionally, the generator torque control device employs piecewise function control, comprising multiple control regions; the control regions include: a first region, a second region, a third region, a fourth region, and a fifth region; When in the first zone, where the inflow wind speed is less than the cut-in wind speed at turbine startup, the turbine engages the brakes and maintains generator torque. When in the second zone, where the inflow wind speed is greater than the cut-in wind speed but less than the rated wind speed, the turbine begins to utilize wind energy, and the generator torque is proportional to the turbine speed to maintain a better power coefficient. When in the third zone, where the inflow wind speed further increases and the speed also increases accordingly, the generator torque is adjusted to be proportional to the square of the speed. When in the fourth zone, where the wind speed is close to the rated wind speed and the generator speed is also close to the rated speed, the generator torque and speed are readjusted to a linear relationship. When in the fifth zone, where the inflow wind speed exceeds the rated design value but is less than the cut-out wind speed, the blade pitch angle is used to adjust the power and maintain a constant generator torque. Furthermore, when the inflow wind speed exceeds the cut-out wind speed, the blade pitch angle is adjusted to minimize aerodynamic load in the downwind direction, and the turbine decelerates until it stops.

[0013] Optionally, the system also includes: The floating wind turbine integral yaw module, composed of tapered roller bearings and installed at the bottom of the tower, is used to work in conjunction with the central control module to achieve wind control.

[0014] To achieve the above objectives, the present invention provides a method for aerodynamic coordination of rotors in a side-by-side multi-rotor offshore floating wind turbine, comprising: Collect the overall wind speed and direction of the wind turbine and the local wind speed and direction of each rotor to obtain the first monitoring data; collect the rotor speed at the main shaft or generator shaft end and monitor the power generation to obtain the second monitoring data. The wind turbine's operating status is determined by the first and second monitoring data, and the determination result is obtained. Based on the determination result, the corresponding control mode is selected, and aerodynamic power or thrust sub-targets are allocated to each rotor. Command signals for the rotational speed and blade pitch angle of each rotor are generated. Based on the command signals, the main shaft speed and blade pitch angle of each rotor are independently adjusted.

[0015] The beneficial effects of this invention are as follows: Global Cooperative Optimization: This invention uses a two-layer nested control architecture to decompose system-level power, load, and motion targets into rotor-level sub-targets, achieving global optimization and coordination of multi-rotor aerodynamic behavior, rather than isolated single-rotor control.

[0016] Active load suppression: This invention is the first to clearly propose and implement active load suppression technology for towers based on aerodynamic thrust balance in the control of parallel multi-rotor floating wind turbines, which is expected to significantly extend the fatigue life of key structural components.

[0017] Pneumatic Assisted Yaw: This invention creatively utilizes the thrust difference of multiple rotors to generate yaw assist torque for a multi-rotor system, combining pneumatic control with motion control to improve yaw efficiency and reduce the load and energy consumption of traditional yaw mechanisms.

[0018] Full-condition adaptability: By dividing different operating states and adopting corresponding control strategies, this invention enables the system to effectively cope with various complex operating conditions such as normal power generation, wind direction changes, and local faults, thereby enhancing the robustness and practicality of the system. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the rotor aerodynamic coordination system of a parallel multi-rotor offshore floating wind turbine according to an embodiment of the present invention; Figure 2 This is a flowchart illustrating the logic of a two-layer nested control algorithm according to an embodiment of the present invention. Figure 3 This is a piecewise function control diagram of the generator torque in the inner layer of the rotor adjustment according to an embodiment of the present invention; Figure 4 This is a flowchart of the rotor adjustment inner layer pitch angle controller according to an embodiment of the present invention; Among them, 11, 12, 13, 14 - rotors, 10 - four-rotor generator set, 20 - wind speed measuring instrument, 30 - tower support structure, 31 - yaw bearing, 40 - support platform, 50 - mooring system, and 60 - central controller. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] like Figure 1As shown, this embodiment discloses a rotor aerodynamic coordination system for a parallel multi-rotor offshore floating wind turbine, including: a wind speed-direction measurement module, used to collect the overall wind speed-direction of the wind turbine and the local wind speed-direction of each rotor to obtain first monitoring data; a rotor power generation status monitoring module, used to collect the rotor speed at the main shaft or generator shaft end and monitor the power generation to obtain second monitoring data; a central control module, used to determine the wind turbine operating status through the first and second monitoring data, obtain the determination result, select the corresponding control mode according to the determination result, allocate aerodynamic power or thrust sub-targets to each rotor, and generate command signals for the rotational speed and blade pitch angle of each rotor; and a rotor aerodynamic adjustment execution module, used to independently adjust the main shaft speed and blade pitch angle of each rotor according to the command signals.

[0024] Specifically, this embodiment discloses a rotor aerodynamic coordination system for a side-by-side multi-rotor offshore floating wind turbine, including: A wind speed-direction measurement system is used to measure the ambient wind speed and direction of the floating wind turbine in real time, and simultaneously measure the local wind speed and direction in front of each rotor. It preferably includes an anemometer located at the top of the tower, and a local ultrasonic anemometer individually configured for each rotor and located in front of each rotor nacelle.

[0025] The rotor condition monitoring system is used to measure the rotational speed and power output of each rotor. It uses Hall effect sensors to monitor the rotor speed at the main shaft or generator shaft end and a power transmitter to monitor the power output in real time.

[0026] Central control system: Communicates with all the aforementioned monitoring systems, receives measurement signals, and serves as the control core. Its built-in two-layer nested control algorithm includes: Outer Coordinator: Based on the overall system status (such as total power target, wind speed-wind direction conditions), combined with expert system strategies, and according to the current operating status of the wind turbine (normal power generation, wind direction change, partial rotor failure), it assigns sub-targets (such as individual target power or target thrust) to each rotor.

[0027] Inner layer controller: Independently configured for each rotor, employing shaft torque control based on piecewise function control and pitch controller based on PID (proportional-integral-derivative) algorithm to accurately track the aerodynamic loads and power sub-targets allocated by the outer layer coordinator.

[0028] The rotor pneumatic adjustment actuator is connected to the central control system and is used to receive and execute the instructions issued by the central control system to independently adjust the main shaft speed (controlled by generator torque) and blade pitch angle of the corresponding rotor.

[0029] The overall yaw system of a floating wind turbine is usually a single-point mooring system or an active yaw drive mechanism installed at the bottom of the tower. It works in conjunction with the central control system to achieve wind alignment.

[0030] More specifically, this embodiment takes a parallel four-rotor floating wind turbine with a total power of 20MW as an example, including: rotors 11, 12, 13, and 14, a four-rotor generator set 10, an anemometer 20, a tower support structure 30, a floating body support structure 40, a mooring system 50, and a central controller 60.

[0031] Furthermore, the four-rotor generator set 10 comprises four independent rotor generators, which are mounted on the tower support structure 30. The tower support structure consists of a main tower structure, two transverse strut structures, and four diagonal strut structures.

[0032] Furthermore, the anemometer 20 can be a radar anemometer or an anemometer-wind direction meter, installed on top of the tower support structure 30, to measure the overall wind speed and direction of the wind turbine system.

[0033] Furthermore, the yaw bearing 31 is part of the tower support structure 30, located at the bottom of the tower, and is made of tapered ball bearings. It can bear the weight of the tower and the wind turbine, and can rotate around the center line of the tower when subjected to aerodynamic driving torque.

[0034] Furthermore, the floating support structure 40 provides buoyancy by displacing water through a floating structure and has multiple internal compartments. Some compartments are empty to improve water ingress isolation in the event of float failure, while others are filled with liquid fresh water to adjust the float's center of gravity and improve its stability. This embodiment uses a three-column semi-submersible floating wind turbine foundation.

[0035] Furthermore, the mooring system 50 includes a guide, locking device, mooring cable, and anchorage structure. This embodiment employs a catenary anchor chain structure.

[0036] The operation process of the parallel multi-rotor offshore floating wind turbine rotor aerodynamic coordination system is as follows: Figure 2 As shown, the anemometer measures the wind speed and direction of the incoming wind. The rotor speed and power monitoring system uses a Hall sensor to monitor the rotor speed at the main shaft or generator shaft end, and a power transmitter to measure the power generation in real time. The above monitoring signals are transmitted to the central controller host system through the data acquisition module, and then the current operating status of the multi-rotor wind turbine is identified, which is mainly divided into: Condition 1: The wind turbine is operating normally and the air velocity uniformity is good; Condition 2: The wind turbine is operating normally but the air velocity uniformity is poor; Condition 3: Some rotors are faulty; Condition 4: All rotors are faulty; Condition 5: The wind turbine is operating normally but the wind direction is off.

[0037] Furthermore, the two-layer collaborative control method includes outer-layer control and inner-layer control, such as... Figure 2 As shown.

[0038] Furthermore, the outer control loop optimizes the overall system performance. An anemometer measures the inflow wind speed and direction, a Hall effect sensor monitors the rotor speed at the main shaft or generator shaft end, and a power transmitter measures power generation in real time. These monitoring signals are transmitted to the central controller system via a data acquisition module. A pre-trained decision tree method can be used to identify the wind turbine system status. The status includes five typical conditions: uniform wind speed distribution and normal rotor operation; significant spatial variation in wind speed distribution and normal rotor operation; overall wind direction deviation but normal rotor operation; partial rotor failure; and complete rotor failure. The first three are normal operating conditions, and the latter two are fault conditions.

[0039] Furthermore, when the wind speed distribution is uniform and the rotors are functioning normally, each rotor is controlled independently and integrated into the inner control loop. When the wind speed distribution varies significantly and the rotors are functioning normally, the rotor with lower wind speed adjusts its pitch angle to be smaller, and the rotor with higher wind speed adjusts its pitch angle to be larger, until the aerodynamic thrust of each rotor is consistent. When the wind direction is deflected overall but the rotors are functioning normally, the rotor downstream of the wind direction adjusts its pitch angle to be larger, reducing aerodynamic thrust, while the rotor upstream of the wind direction adjusts its pitch angle to be smaller, increasing aerodynamic thrust. This generates a torque that rotates around the yaw axis until the wind deviation angle is eliminated.

[0040] Furthermore, when some rotors fail, the system prioritizes load balancing. The outer coordinator will re-optimize the power output of the remaining normal rotors to significantly reduce the unbalanced bending moment caused by the lack of thrust from the failed rotor. Specifically, the aerodynamic thrust of the remaining normal rotors on the failed side is increased, while the aerodynamic thrust of the normal rotors on the other side is decreased, ensuring a consistent total aerodynamic thrust on both sides. Each normal rotor then performs pitch-torque control based on the new power target. When all rotors fail or the system's unbalanced load exceeds limits, the failed rotors can be instructed to feather and shut down, and the operating points of other rotors can be further adjusted to ensure system safety.

[0041] The outer control loop acts as a global coordinator, its core function being system state identification based on multi-source sensor data and rule-based optimization command allocation. Assume the system includes... N One rotor unit (in this embodiment) N =4), define the first i The sensor measurement vector at each rotor is Z i =[ V i ,i wind,i ,oh i ,P i ] T ,in, V i For the inflow wind speed, i wind,i For wind direction, oh i The rotor speed is P i The output represents the power generation capacity; the superscript T indicates the vector transpose. The output of the outer controller is the target power setpoint for each rotor. P ref,i Or target pitch angle compensation value Db ref,i .

[0042] The outer controller uses a pre-trained decision tree model to perform real-time state identification of the wind turbine system. The feature vector X is defined. feat Including wind speed spatial variance Mean wind direction deviation and rotor fault flag F lt : X feat =[ , ,F lt ] T ; Among them, wind speed spatial variance = , Average wind speed; wind direction deviation Used to characterize the overall degree of wind direction deviation, fault flag vector F lt ∈{0,1} N , This is a review of rotors.

[0043] Define state variable S state The decision logic of a decision tree is expressed as follows: ; In the formula, and These are the thresholds for wind speed uniformity and wind deviation, respectively. S1 to S5 correspond to five states: "normal wind speed uniformity", "large wind speed difference", "wind direction deviation", "partial rotor failure" and "serious failure".

[0044] Mathematical expressions of control laws in each state mode: (1) State S1: The wind speed is spatially uniform and the rotor is normal; In this state, each rotor operates independently, and the outer controller sets the reference value of the inner control loop to the rated optimal value without applying any additional intervention. P ref,i =P rated ; Db ref,i =0, ∀ i ∈{1,…,N}; At this point, the system mainly relies on the inner control loop for maximum power point tracking or constant power control.

[0045] (2) State S2: The wind speed distribution varies greatly in space and the rotor is normal: The control objective is to minimize the aerodynamic thrust difference between the rotors to balance the platform load. The thrust balance objective function is defined. J balance And solve for the target thrust value of each rotor. F target : in, Based on the approximate relationship between aerodynamic thrust and wind speed and propeller pitch angle The outer controller outputs pitch angle compensation commands to adjust thrust. The specific control law is as follows: Δβ ref,i =K bal ⋅( ); In the formula K bal >0 represents the balanced gain coefficient. air density, For the area of ​​the propeller disk, This is the rotor aerodynamic thrust coefficient. The rotor tip speed ratio, This refers to the propeller pitch angle. When the local wind speed... When, Δβ ref,i If the thrust is greater than 0, the pitch angle is increased to reduce thrust; conversely, if the thrust is less than 0, the pitch angle is decreased to increase thrust, until the aerodynamic thrust of each rotor becomes consistent.

[0046] (3) State S3: The wind direction is deflected overall but the rotor is normal: The control objective is to generate a steering torque M. yaw To eliminate wind deviation angle The required corrective torque command is calculated based on the wind deviation: M cmd =K p_yaw ⋅ +K d_yaw ⋅ ; Based on the spatial azimuth angle ψ of each rotor i (Relative to wind direction) The outer controller assigns differentiated thrust commands to generate the torque. For rotors located upstream or downstream of the wind direction, the following pitch angle allocation strategy is used: Dbref,i =−K yaw ⋅ M cmd ⋅sgn( r i ⋅n wind ); In the formula, r i For the first i The position vector of each rotor n wind This is a unit vector representing the wind direction. Specifically, the rotor located upstream receives negative pitch angle compensation (reducing the pitch angle to increase thrust), while the rotor located downstream receives positive pitch angle compensation (increasing the pitch angle to reduce thrust), thus creating a steering torque around the central axis of the tower, until... .

[0047] (4) State S4: Part of the rotor has failed. Let the set of faulty rotors be Ω. fault The normal rotor assembly is Ω normal The control objective is to minimize the unbalanced torque M. unbal The outer controller recalculates the thrust distribution: ; To achieve load balance, the normal rotor on the side of the faulty rotor needs to increase its aerodynamic thrust, while the normal rotor on the other side needs to decrease its thrust. The power reference command is then adjusted as follows: P ref,i = P opt,i + ΔP comp,i ,i ∈ Oh normal ; Among them, the compensation term ΔP comp,i This is derived from the torque balance equation and aims to counteract the unbalanced bending moment caused by the lack of thrust from the faulty rotor, thus ensuring the stability of the platform's attitude.

[0048] (5) State S5: All rotors have failed or the load has exceeded the limit: The safety protection mechanism is triggered, and the outer controller sends a feathering shutdown command to all rotors: β ref,i = β feather , T brake,i =1, ∀ i ∈{1,…,N}; in, β featherfeathering angle (usually 90 degrees) ∘ ), T brake This is a braking command. Further, the outer controller generates... P ref,i With Δ β ref,i The setpoint is input to the inner control loop, and the inner controller executes specific servo control based on the aforementioned piecewise torque function and PI pitch algorithm to achieve the system-level optimization goal.

[0049] Furthermore, the interface between the outer controller and the inner controller is completed through the transmission of target power setpoints: the outer controller calculates the real-time target power of each normally operating rotor based on the decision logic of the aforementioned states, and sends it as a setpoint to the inner control loop corresponding to that rotor. The inner control loop (such as...) Figure 3 and Figure 4 The torque and pitch controller shown will take tracking this given target as its core control objective, independently adjusting the generator torque and blade pitch angle to achieve rapid and stable power tracking.

[0050] Furthermore, the inner control loop is designed independently for each rotor, employing a torque controller based on piecewise function control and a pitch controller based on a PID algorithm. The control flow of the piecewise function control torque controller is as follows: Figure 3 As shown, the pitch controller based on the PID algorithm is as follows: Figure 4 As shown. This controller uses the target power received from the outer controller as the set value, and adjusts the generator torque and blade pitch angle to make the actual output power of the rotor quickly and smoothly track the target value set by the outer controller.

[0051] Furthermore, when the wind turbine is operating normally and below its rated operating conditions, the generator torque controller is primarily used to maintain the optimal tip speed ratio of the wind turbine to maximize wind energy capture efficiency. Above the rated operating conditions, the pitch angle controller is primarily used to constrain and stabilize the generator speed and power, preventing overload and exceeding limits.

[0052] Furthermore, since the generator torque controller uses the generator speed as the signal source, in order to filter out high-frequency components in the signal and avoid frequent responses from the controller, the following low-pass filters can be used for signal smoothing: (1); in, This is the generator speed signal after filtering. It is the raw generator speed measurement signal without filtering. If it is the current value of the number of discrete time intervals, then... This represents the value from the previous step. These are the coefficients of the low-pass filter. , It is a discrete time interval. That is the corresponding angular frequency.

[0053] For the torque control system, piecewise function control is used, which includes five control regions, such as... Figure 3 As shown, these are the first, second, third, fourth, and fifth regions. The relationship between generator torque and speed in each region is as follows: (1) First zone: The ambient inflow velocity is less than the cut-in velocity when the fan starts ( (When wind energy density is low, the wind turbine engages its brakes and does not utilize wind energy; the generator torque remains at 0.) ; (2) Second and third zones: At this time, the wind speed is greater than the cut-in wind speed but less than the rated wind speed. Based on different rotational speeds, it can be further divided into three stages: Zone 2, Zone 2½, and Zone 3. In Zone 2, the wind turbine begins to utilize wind energy, and the generator torque is proportional to the turbine speed to maintain a better power coefficient; at this point, a linear relationship exists. When the wind speed increases further, the rotational speed also increases accordingly. At this point, the generator enters region 2½, and the generator torque is adjusted to be proportional to the square of the rotational speed, as follows: When the wind speed approaches the rated wind speed, that is, the generator speed also approaches the rated speed, at this time we enter region 3, where the generator torque and speed are readjusted to a linear relationship, serving as a transition region between rated and non-rated operating conditions. At this time, we have: .

[0054] (3) Fourth zone: When the wind speed exceeds the rated design value but is less than the cut-out wind speed ( Therefore, power is no longer regulated by the generator's torque, but by the blade pitch angle, thus maintaining a constant generator torque. When the wind speed exceeds the cut-out wind speed ( The blades adjust the pitch angle to minimize aerodynamic load in the downwind direction, at which point the wind turbine decelerates until it stops.

[0055] in, The ambient inflow velocity measured for each rotor, In this embodiment, the cutoff wind speed is 3 m / s. When the ambient wind speed exceeds this value, the wind turbine shaft can be loosened to start generating electricity. This is the rated wind speed of the fan. It is the output wind speed of the fan; It is the linear proportional coefficient of the fan shaft torque control function when the rotational speed enters region 2. It is the coefficient representing the relationship between the generator torque and the square of the speed when the speed enters region 3. It is the linear proportional coefficient of the fan shaft torque control function when the rotational speed enters region 4. The rotor speed is The threshold rotational speed for region 3. The threshold rotation speed is for region 4.

[0056] Furthermore, when the fifth zone is reached (the inflow wind speed is greater than the rated wind speed but lower than the cut-out wind speed), the pitch angle controller will perform pitch adjustment. The pitch angle controller of this invention adopts a unified pitch controller for the entire spanwise direction and uses a proportional-integral (PI) control algorithm to constrain the generator speed and power generation after the rated operating condition based on the difference between the filtered generator speed value and the predetermined value.

[0057] Furthermore, the pitch angle controller The PI control equation is as follows Figure 4 As shown, it is: (2); The above formula shows that the control signal depends on the error between the preset speed and the actual speed. ,make The system's natural frequency is The system damping rate is Then the above proportionality coefficient and integral coefficient They are respectively: (3); (4); In the formula, Indicates aerodynamic power pitch angle The derivative of The value at time; It is a dimensionless gain correction factor, which can be adjusted according to different propeller pitch angles. The coefficients of the proportional and integral terms are dynamically adjusted. This means that when the pitch angle is this value, the derivative of the power with respect to the pitch angle is... Twice as long as, For time, The moment of inertia of the transmission shaft system. The rotational speed of the shaft. This is the initial scaling factor. This represents the transmission ratio between the high-speed shaft and the low-speed shaft. represents the initial integration coefficients.

[0058] This invention overcomes the problem of multi-rotor floating wind turbines being difficult to work in a coordinated manner by providing a rotor aerodynamic control system and method suitable for parallel multi-rotor floating wind turbines. It provides strong technical support for the further development of offshore wind power and has good economic and social benefits.

[0059] This embodiment also provides a method for aerodynamic coordination of rotors in a parallel multi-rotor offshore floating wind turbine, including: collecting the wind speed-direction of the entire wind turbine and the local wind speed-direction of each rotor to obtain first monitoring data; collecting the rotor speed at the main shaft or generator shaft end and monitoring the power generation to obtain second monitoring data; judging the wind turbine operating status through the first and second monitoring data, obtaining the judgment result; selecting the corresponding control mode according to the judgment result; allocating aerodynamic power or thrust sub-targets to each rotor; generating command signals for the rotational speed and blade pitch angle of each rotor; and independently adjusting the main shaft rotational speed and blade pitch angle of each rotor according to the command signals.

[0060] Specifically, this embodiment also provides a method for the aerodynamic coordination of rotors in a side-by-side multi-rotor offshore floating wind turbine, including the following steps: S1. Real-time acquisition of wind speed-wind direction signals and operating signals of each rotor generator through various measurement systems; S2. The central control system determines the operating status of each wind turbine based on information and selects the corresponding control mode accordingly, allocating aerodynamic power or thrust sub-targets to each rotor. S3. Each rotor's pneumatic adjustment actuator independently adjusts the rotor speed and blade pitch angle according to the assigned sub-target. S4. When the controller determines that there is a spatial difference in the inflow velocity of each rotor based on the monitoring signal, it enters the load balancing mode and adjusts the thrust of each rotor to reduce the uneven load on the tower. S5. When the controller determines that a rotor has failed and stopped based on the monitoring signal, it enters the load balancing mode and adjusts the thrust of each rotor to eliminate the load imbalance caused by the faulty fan. S6. When the controller determines that the wind direction is generally skewed based on the monitoring signal, it enters the active yaw mode and adjusts the thrust of each rotor to generate an auxiliary yaw torque.

[0061] It should be noted that, in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0062] It should be noted that, in the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

Claims

1. A parallel multi-rotor offshore floating wind turbine rotor aerodynamic coordination system, characterized in that, include: The wind speed-direction measurement module is used to collect the wind speed-direction of the entire wind turbine and the local wind speed-direction of each rotor to obtain the first monitoring data. The rotor power generation status monitoring module is used to collect the rotor speed at the main shaft or generator shaft end, monitor the power generation, and obtain secondary monitoring data. The central control module is used to determine the operating status of the wind turbine through the first monitoring data and the second monitoring data, obtain the judgment result, select the corresponding control mode according to the judgment result, allocate aerodynamic power or thrust sub-targets to each rotor, and generate command signals for the rotational speed and pitch angle of each rotor. The rotor pneumatic adjustment actuator module is used to independently adjust the main shaft speed and blade pitch angle of each rotor according to the command signal.

2. The parallel multi-rotor offshore floating wind turbine rotor aerodynamic coordination system according to claim 1, characterized in that, The central control module includes: The outer coordinator is used to determine the operating status of the wind turbine through the first monitoring data and the second monitoring data, select the corresponding control mode, and allocate sub-targets of aerodynamic power or thrust to each rotor. The inner controller, used by the generator torque control device and the unified pitch control device based on the PID algorithm, generates command signals for the rotational speed and pitch angle of each rotor as setpoints from the sub-targets.

3. The parallel multi-rotor offshore floating wind turbine rotor aerodynamic coordination system according to claim 2, characterized in that, The outer coordinator includes: The status judgment unit is used to judge the operating status of the fan through the first monitoring data and the second monitoring data, and obtain the judgment result. The judgment result includes: the fan is operating normally and the space wind speed uniformity is good, the fan is operating normally but the space wind speed uniformity is poor, there is a partial rotor fault, all rotor faults, and the fan is operating normally but the wind direction is off.

4. The parallel multi-rotor offshore floating wind turbine rotor aerodynamic coordination system according to claim 3, characterized in that, The outer coordinator also includes: The mode control unit is used to select the corresponding control mode based on the judgment result. That is, when the wind speed is uniformly distributed in space and the rotor is normal, each rotor is controlled independently and the inner control loop is activated. That is, a proportional-derivative control model is used to control the pitch angle of each rotor based on the shaft speed signal. When the wind turbine is operating normally but the uniformity of the wind speed in space is poor, the rotor with the lower wind speed is adjusted to a smaller pitch angle, while the rotor with the higher wind speed is adjusted to a larger pitch angle, until the aerodynamic thrust of each rotor is consistent. When the wind turbine is operating normally but the wind direction is biased, the rotor located downstream of the wind direction is adjusted to a larger pitch angle, while the rotor located upstream of the wind direction is adjusted to a smaller pitch angle, so as to generate a torque for rotating around the yaw axis, until the deviation angle of the wind is eliminated. When a partial rotor failure occurs, the power output of the remaining normal rotors is re-optimized with the goal of load balance. That is, the aerodynamic thrust of the remaining normal rotors on the faulty side is increased, and the aerodynamic thrust of the normal rotors on the other side of the fault is decreased, so that the total aerodynamic thrust on both sides is consistent to maintain the load balance of the wind turbine system. When all rotor failures occur, the faulty rotor is instructed to feather and stop.

5. The parallel multi-rotor offshore floating wind turbine rotor aerodynamic coordination system according to claim 4, characterized in that, The outer coordinator also includes: The first target allocation unit is used to allocate aerodynamic power or thrust sub-targets to each rotor based on the selected control mode. That is, when the wind speed spatial distribution is uniform and the rotors are normal, each rotor operates independently, and the reference value of the inner control loop is set to the rated optimal value without additional intervention. P ref,i =P max ； Δβref,i =0, ∀ i ∈{1,…,N}； in, Pref,i The target power setpoints allocated to each rotor by the outer controller. Pmax This represents the maximum power that the rotor can actually achieve. Δβref,i The first layer allocated to the outer controller i The pitch angle compensation value for each rotor. i The rotor sequence is N, and the total number of rotors is N. When the fan is operating normally but the airflow uniformity in the space is poor, the control objective is to minimize the aerodynamic thrust difference between the rotors to balance the platform load. That is, a thrust balance objective function is defined, and the thrust target value of each rotor is solved: in, , Let the rotor thrust balance objective function be... Let be the aerodynamic thrust value of the i-th rotor. This represents the average rotor aerodynamic thrust value. Further, based on the approximate relationship between aerodynamic thrust and wind speed and pitch angle, a pitch angle compensation command is output to adjust the thrust. Δβref,i=Kbal⋅( ) In the formula, K bal Δβ is the balance gain coefficient. ref,i This is the pitch angle compensation value for the i-th rotor. Let be the inflow velocity of the i-th rotor. The average inflow velocity of the rotor; When the wind turbine is operating normally but the wind direction is off, the control objective is to generate a corrective torque to eliminate the wind deviation angle, that is, to calculate the required corrective torque command based on the wind deviation: Mcmd=Kp_yaw⋅ +Kd_yaw⋅ ; Among them, M cmd To correct the course torque for the target, For the wind deviation angle, K p_yaw K is the proportionality coefficient. d_yaw These are the differential coefficients. t For time; further, differentiated thrust commands are allocated based on the spatial azimuth angle of each rotor to generate the torque: Δβ ref,i =−K yaw ⋅ M cmd ⋅sgn( r i ⋅n wind ); In the formula, ri is the th i The position vector of each rotor nwind This is a unit vector representing wind direction. Δβref,i For the first i The pitch angle compensation value for each rotor, Kyaw is the yaw control coefficient, and sgn is the sign function; When the aforementioned local rotor fault occurs, the control objective is to minimize the unbalanced torque, i.e., to recalculate the thrust distribution: ； in, For normal rotor assembly, For the set of faulty rotors, For the first i The position vector of each rotor For the first j The position vector of each rotor Furthermore, the normal rotor located on the side of the faulty rotor needs to have its aerodynamic thrust increased, while the normal rotor on the other side needs to have its thrust reduced: P ref,i = P opt,i + ΔP comp,i ,i ∈ Ω normal ； In the formula, ΔPcomp,i is the power compensation term. Pref,i The target power setpoints allocated to each rotor by the outer controller. Popt,i The optimal power for the rotor; When the aforementioned local rotor fault occurs, the safety protection mechanism is triggered, and a feathering shutdown command is issued to all rotors: β ref,i = β feather , T brake,i =1, ∀ i ∈{1,…,N}； in, βref,i For the first i The pitch angle of each rotor, βfeather This is the feathering angle, usually 90°. Tbrake This is a braking command.

6. The parallel multi-rotor offshore floating wind turbine rotor aerodynamic coordination system according to claim 2, characterized in that, The inner controller includes: The second target allocation unit is used to determine whether a normally operating wind turbine is below its rated operating condition. When the normally operating wind turbine is below its rated operating condition, the target is to maintain the optimal tip speed ratio of the wind turbine and maximize wind energy capture efficiency. The generator torque control device is the primary unit, and the unified pitch control device is the secondary unit. The sub-target is used as the set value to generate command signals for the rotational speed and pitch angle of each rotor. When the normally operating wind turbine is above its rated operating condition, the target is to constrain and stabilize the generator speed and power. The unified pitch angle control device is the primary unit, and the generator torque control device is the secondary unit. The sub-target is used as the set value to generate command signals for the rotational speed and pitch angle of each rotor.

7. The parallel multi-rotor offshore floating wind turbine rotor aerodynamic coordination system according to claim 2, characterized in that, The generator torque control device employs piecewise function control, comprising multiple control regions; the control regions include: a first region, a second region, a third region, a fourth region, and a fifth region; When in the first zone, where the inflow wind speed is less than the cut-in wind speed at turbine startup, the turbine engages the brakes and maintains generator torque. When in the second zone, where the inflow wind speed is greater than the cut-in wind speed but less than the rated wind speed, the turbine begins to utilize wind energy, and the generator torque is proportional to the turbine speed to maintain a better power coefficient. When in the third zone, where the inflow wind speed further increases and the speed also increases accordingly, the generator torque is adjusted to be proportional to the square of the speed. When in the fourth zone, where the wind speed is close to the rated wind speed and the generator speed is also close to the rated speed, the generator torque and speed are readjusted to a linear relationship. When in the fifth zone, where the inflow wind speed exceeds the rated design value but is less than the cut-out wind speed, the blade pitch angle is used to adjust the power and maintain a constant generator torque. Furthermore, when the inflow wind speed exceeds the cut-out wind speed, the blade pitch angle is adjusted to minimize aerodynamic load in the downwind direction, and the turbine decelerates until it stops.

8. The parallel multi-rotor offshore floating wind turbine rotor aerodynamic coordination system according to claim 1, characterized in that, The system also includes: The floating wind turbine integral yaw module, composed of tapered roller bearings and installed at the bottom of the tower, is used to work in conjunction with the central control module to achieve wind control.

9. The method for aerodynamic coordination of rotors in a parallel multi-rotor offshore floating wind turbine implemented according to any one of claims 1-8, characterized in that, include: Collect the overall wind speed and direction of the wind turbine and the local wind speed and direction of each rotor to obtain the first monitoring data; collect the rotor speed at the main shaft or generator shaft end and monitor the power generation to obtain the second monitoring data. The wind turbine's operating status is determined by the first and second monitoring data, and the determination result is obtained. Based on the determination result, the corresponding control mode is selected, and aerodynamic power or thrust sub-targets are allocated to each rotor. Command signals for the rotational speed and blade pitch angle of each rotor are generated. Based on the command signals, the main shaft speed and blade pitch angle of each rotor are independently adjusted.

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