Multi-domain coupling analysis method and system for floating hybrid wind-wave power generation system

Abstract

The application relates to the technical field of coupling analysis, and discloses a multi-domain coupling analysis method and system for a floating hybrid wind-wave power generation system. The method comprises the following steps: establishing a multi-domain parameter initialization data packet, substituting the data packet into a Cummins motion equation and a BEM module to obtain a platform six-degree-of-freedom motion response and an aerodynamic load vector, substituting the platform six-degree-of-freedom motion response into a hydraulic PTO nonlinear pressure-flow dynamic equation to obtain a pressure pulsation characteristic vector, and converting the pressure pulsation characteristic vector into comprehensive variable-pitch instructions through a platform transfer function and a blade root bending moment sensitivity matrix in a step-by-step manner to complete three-stage reverse coupling correction. The application solves the problems that, in the existing multi-domain coupling analysis method, a reverse disturbance path of hydraulic PTO pressure pulsation to an aerodynamic control domain is missing, and a variable-pitch controller cannot implement feedforward compensation on platform pitching disturbance induced by the hydraulic system.

Description

Technical Field

[0001] This application relates to the field of coupling analysis technology, and in particular to a multi-domain coupling analysis method and system for a floating hybrid wind and wave power generation system. Background Technology

[0002] Floating hybrid wind and wave power generation systems integrate floating offshore wind turbines and wave energy conversion devices onto the same semi-submersible platform. By sharing the platform structure and mooring system, they achieve the synergistic development of wind and wave energy, representing an important technological direction for the comprehensive utilization of renewable energy in deep-sea areas. Existing multi-domain coupling analysis methods for this system typically employ a multi-software collaborative framework as the mainstream approach. A typical approach is to establish a coupled computational framework based on software such as OpenFAST and ANSYS-AQWA, WEC-Sim, etc. After applying aerodynamic loads unidirectionally to the floating platform, the hydrodynamic equations are used to solve for the platform's motion response. The hydraulic PTO (Power Take-Off) system is generally simplified using a linear spring-damped model or a Coulomb-damped model. Data exchange between the various physical domains is completed sequentially through software interfaces.

[0003] However, the aforementioned existing technologies have the following shortcomings: When calculating the equivalent inflow velocity of each blade element, the aerodynamic module only uses a single translational velocity correction at the hub center, ignoring the differential influence of the platform's pitch and roll angular velocities on blade elements at different spanwise positions, resulting in the systematic smoothing of the non-uniform distribution characteristics of blade element aerodynamic forces; the linear simplification of the hydraulic PTO system ignores the nonlinear characteristics of the high-pressure chamber volume changing with piston displacement, the adiabatic compression characteristics of the accumulator gas, and the nonlinear damping effect of sealing friction, causing the actual reverse disturbance force of the hydraulic PTO on the platform motion to be underestimated; the more fundamental defect is that each physical domain in the existing framework is solved in a fixed parameter order, and there is no reverse coupling path between the hydraulic domain, hydrodynamic domain, and aerodynamic control domain. The disturbance effect of hydraulic PTO pressure pulsation transmitted to the aerodynamic domain through platform motion completely depends on the natural digestion of feedback control. Summary of the Invention

[0004] This application provides a multi-domain coupling analysis method and system for a floating hybrid wind and wave power generation system. It solves the problems in existing multi-domain coupling analysis methods, such as the lack of a reverse disturbance path for hydraulic PTO pressure pulsation in the aerodynamic control domain and the inability of the pitch controller to perform feedforward compensation for hydraulically induced platform pitch disturbances. This improves the accuracy of aerodynamic-platform coupling stability analysis and the timeliness of pitch control response of the floating hybrid wind and wave power generation system under hydraulic pulsation excitation.

[0005] In a first aspect, this application provides a multi-domain coupling analysis method for a floating hybrid wind-wave power generation system, the multi-domain coupling analysis method for the floating hybrid wind-wave power generation system comprising: Step S1: Based on the structural parameters of the floating hybrid wind and wave power generation system and the parameters of the hydraulic PTO system, establish a multi-domain parameter initialization data package; Step S2: Substitute the multi-domain parameter initialization data package into the Cummins motion equation and BEM module to obtain the platform's six-degree-of-freedom motion response and aerodynamic load vector. Step S3: Substitute the six-degree-of-freedom motion response of the platform into the nonlinear pressure-flow dynamic equation of the hydraulic PTO to obtain the pressure pulsation characteristic vector and the hydraulic PTO reaction force vector. Step S4: The pressure pulsation feature vector is mapped to the platform additional pitch motion component through the platform transfer function. The platform additional pitch motion component is converted into the equivalent inflow wind speed correction amount of the leaf element according to the spanwise position. The equivalent inflow wind speed correction amount of the leaf element is converted into the pitch feedforward compensation angle through the blade root bending moment sensitivity matrix. The pitch feedforward compensation angle is superimposed with the feedback pitch command to obtain the comprehensive pitch command, thus completing the three-level reverse coupling correction between the hydraulic domain, hydrodynamic domain and aerodynamic control domain.

[0006] Secondly, this application provides a multi-domain coupling analysis system for a floating hybrid wind and wave power generation system, the multi-domain coupling analysis system for the floating hybrid wind and wave power generation system comprising: The analysis module is used to establish a multi-domain parameter initialization data package based on the structural parameters of the floating hybrid wind and wave power generation system and the parameters of the hydraulic PTO system; The calculation module is used to substitute the multi-domain parameter initialization data package into the Cummins motion equation and the BEM module to obtain the platform's six-degree-of-freedom motion response and aerodynamic load vector. The generation module is used to substitute the six-degree-of-freedom motion response of the platform into the nonlinear pressure-flow dynamic equation of the hydraulic PTO to obtain the pressure pulsation characteristic vector and the hydraulic PTO reaction force vector. The correction module is used to map the pressure pulsation feature vector into an additional pitch motion component of the platform via the platform transfer function, convert the additional pitch motion component into a leaf element equivalent inflow wind speed correction amount according to the spanwise position, convert the leaf element equivalent inflow wind speed correction amount into a pitch feedforward compensation angle via the blade root bending moment sensitivity matrix, and superimpose the pitch feedforward compensation angle with the feedback pitch command to obtain a comprehensive pitch command, thus completing the three-level reverse coupling correction between the hydraulic domain, hydrodynamic domain and aerodynamic control domain.

[0007] Thirdly, a multi-domain coupling analysis device for a floating hybrid wind and wave power generation system is provided, comprising: a memory and at least one processor, wherein the memory stores instructions; the at least one processor invokes the instructions in the memory to cause the multi-domain coupling analysis device for the floating hybrid wind and wave power generation system to execute the above-described multi-domain coupling analysis method for the floating hybrid wind and wave power generation system.

[0008] Fourthly, a computer-readable storage medium is provided, wherein instructions are stored therein, which, when executed on a computer, cause the computer to perform the above-described multi-domain coupling analysis method for a floating hybrid wind and wave power generation system.

[0009] The technical solution provided in this application establishes a multi-domain parameter initialization data package, which encapsulates the aerodynamic parameter matrix, platform mass matrix, and hydraulic PTO state equation coefficient matrix in a unified manner and introduces them into a cross-domain correlation constraint matrix. This eliminates the problem of inconsistent dimensional references caused by independent input of each physical domain in the prior art from the parameter reference level, ensuring that the coefficient sources of subsequent domain equations have physical consistency. On this basis, the multi-domain parameter initialization data package is substituted into the simultaneous solution process of the Cummins motion equation and the BEM (Blade Element Momentum) module. By feeding back the platform pitch and roll angular velocities point by point according to the spanwise position and azimuth angle of each blade element to the equivalent inflow wind speed calculation formula, a two-way iterative coupling is formed between the aerodynamic domain and the hydrodynamic domain. This overcomes the inherent defects in the prior art where aerodynamic loads are applied to the floating platform in a unidirectional manner and the influence of platform motion on blade aerodynamic forces is homogenized, so that the platform's six-degree-of-freedom motion response and aerodynamic load vector reach a physically self-consistent convergence state at each time step.

[0010] By substituting the platform's six-degree-of-freedom motion response into the nonlinear pressure-flow dynamic equation of the hydraulic PTO, this invention explicitly describes the real-time change of the high-pressure chamber volume of the hydraulic cylinder with piston displacement, the adiabatic compression characteristics of the accumulator gas, and the nonlinear damping effect of sealing friction. Compared to existing technologies that simplify the hydraulic PTO to a linear spring-damped model, the resulting pressure pulsation characteristic vector accurately reflects the dynamic pressure distribution characteristics of the hydraulic system under wave excitation. Based on this, the invention establishes a three-level reverse coupling correction path between the hydraulic domain, hydrodynamic domain, and pneumatic control domain. The pressure pulsation characteristic vector is mapped to the platform's additional pitch motion component via the platform transfer function, then converted into an equivalent inflow wind speed correction for each blade element based on its spanwise position and azimuth angle. Finally, it is converted into a pitch feedforward compensation angle via the blade root bending moment sensitivity matrix and superimposed with the feedback pitch command to form a comprehensive pitch command. This ensures that the disturbance of the hydraulic PTO pressure pulsation to the pneumatic control domain is canceled out by feedforward compensation before reaching the feedback controller, fundamentally cutting off the transmission path of hydraulic pulsation inducing aerodynamic-platform coupling instability through platform pitch motion. Attached Figure Description

[0011] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of an embodiment of the multi-domain coupling analysis method for a floating hybrid wind and wave power generation system in this application. Figure 2 This is a schematic diagram of the fast Fourier transform spectrum of pressure pulsation in the high-pressure chamber of the hydraulic cylinder in an embodiment of this application. Detailed Implementation

[0013] This application provides a multi-domain coupling analysis method and system for a floating hybrid wind and wave power generation system. The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein. Furthermore, the terms "comprising" or "having" and any variations thereof are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0014] For ease of understanding, the specific process of the embodiments of this application is described below. Please refer to [link / reference]. Figure 1 One embodiment of the multi-domain coupling analysis method for floating hybrid wind and wave power generation systems in this application includes: Step S1: Based on the structural parameters of the floating hybrid wind and wave power generation system and the parameters of the hydraulic PTO system, establish a multi-domain parameter initialization data package; Specifically, the multi-domain parameter initialization data package is a data structure that unifies the physical parameters of the aerodynamic, hydrodynamic, and hydraulic domains. Unlike existing technologies where parameters are input independently for each domain, it additionally establishes a cross-domain correlation constraint matrix. The elements of this matrix reflect the degree of influence of a unit change in a parameter within one physical domain on parameters in adjacent domains. Initial values ​​are determined by taking the partial derivatives after performing a first-order linear expansion of the equations for each domain near the operating point. Structural parameters cover rigid body properties such as platform mass and moment of inertia, while hydraulic PTO system parameters cover core parameters that determine hydraulic dynamic characteristics, such as hydraulic cylinder piston area, accumulator pre-charge pressure, and hydraulic oil bulk modulus.

[0015] Step S2: Substitute the multi-domain parameter initialization data package into the Cummins motion equation and BEM module to obtain the platform's six-degree-of-freedom motion response and aerodynamic load vector. Specifically, the BEM module uses blade element momentum theory to calculate the aerodynamic load on the wind turbine. The blades are discretized along the spanwise direction into several blade element units. Momentum and force equations are established for each blade element. Axial and tangential induction factors are iteratively solved until the deviation between two adjacent iterations is less than a set convergence threshold, yielding the normal and tangential forces of each blade element. Integration yields the aerodynamic load vector composed of aerodynamic thrust and aerodynamic torque. Unlike existing technologies that apply aerodynamic loads unidirectionally, this step feeds back the platform's pitch and roll angular velocities point-by-point according to the spanwise position and real-time azimuth angle of each blade element to the equivalent inflow wind speed calculation formula. This allows blade elements at different azimuth angles to experience differentiated equivalent inflow wind speeds, rather than uniformly using a single velocity correction at the hub center. The aerodynamic load vector then serves as an external force term driving the Cummins equations of motion to solve for the platform's six-degree-of-freedom motion response. The platform's motion response then updates the equivalent inflow wind speed again, forming a bidirectional iterative closed loop.

[0016] Step S3: Substitute the six-degree-of-freedom motion response of the platform into the nonlinear pressure-flow dynamic equation of the hydraulic PTO to obtain the pressure pulsation characteristic vector and the hydraulic PTO reaction force vector. Specifically, the nonlinearity of the hydraulic PTO nonlinear pressure-flow dynamic equation originates from three sources: variable volume nonlinearity caused by the change in high-pressure chamber volume with piston displacement, pressure-volume nonlinearity generated by describing the accumulator gas using an adiabatic process, and nonlinear damping generated by the change in sealing friction with relative velocity. The pressure pulsation feature vector is obtained by averaging the pressure time series of the high-pressure chamber of each WEC (Wave Energy Converter) float hydraulic cylinder within a 10-second sliding window. The pressure pulsation is obtained by subtracting the real-time pressure from the average value. A fast Fourier transform is then used to identify the frequency with the most concentrated pulsation energy as the dominant pulsation frequency. The dominant pulsation frequency of each WEC float and its corresponding pulsation amplitude together constitute the pressure pulsation feature vector. The sliding window width is 10 seconds because the main motion cycle of the floating platform is concentrated in the range of 5 to 20 seconds, and the 10-second window can effectively separate the low-frequency average trend from the high-frequency pulsation component.

[0017] Step S4: Map the pressure pulsation feature vector to the platform additional pitch motion component through the platform transfer function, convert the platform additional pitch motion component into the equivalent inflow wind speed correction amount of the leaf element according to the spanwise position, convert the equivalent inflow wind speed correction amount of the leaf element into the pitch feedforward compensation angle through the blade root bending moment sensitivity matrix, and superimpose the pitch feedforward compensation angle with the feedback pitch command to obtain the comprehensive pitch command, thus completing the three-level reverse coupling correction between the hydraulic domain, hydrodynamic domain and aerodynamic control domain.

[0018] Specifically, the three-level reverse coupling correction is the core mechanism that distinguishes this invention from the existing sequential coupling framework. The three-level transmission paths are as follows: the hydraulic pressure pulsation is mapped to the platform additional pitch motion component through the platform transfer function; the platform additional pitch motion component is projected to the equivalent inflow wind speed correction amount for each blade element according to the spanwise position and azimuth angle of each blade element; and the equivalent inflow wind speed correction amount is converted into the pitch feedforward compensation angle through the blade root bending moment sensitivity matrix. The blade root moment sensitivity matrix is ​​a diagonal matrix. Its diagonal elements are obtained by linearizing the aerodynamic equations in the aerodynamic parameter matrix under rated wind speed conditions, calculating the change in blade root moment corresponding to a unit equivalent inflow wind speed change, and then dividing by the influence coefficient of the unit pitch angle on the blade root moment. The unit is degrees per (meter per second). This matrix directly maps the disturbance of the equivalent inflow wind speed to the optimal pitch compensation required to offset the disturbance. The pitch feedforward compensation angle and the feedback pitch command are superimposed one-to-one according to the blade to form a comprehensive pitch command. Pre-compensation is completed before the hydraulic pulsation disturbance reaches the aerodynamic controller to suppress the aerodynamic-platform coupling instability induced by hydraulic load disturbance.

[0019] In one specific embodiment, step S1 includes: Based on the total mass, center of mass coordinates, six-degree-of-freedom rotational inertia matrix, displacement volume, and waterline area of ​​the floating semi-submersible platform, a platform mass matrix is ​​established. The rated rotational speed, blade radius, rated wind speed, and lift and drag coefficient data at each spanwise position of the wind turbine blade are written into the aerodynamic parameter matrix of the BEM module. The spanwise nodes are discretized according to the blade element spacing to obtain the blade element node coordinate vector. Based on the piston area of ​​the hydraulic cylinder, the pre-charge pressure of the hydraulic accumulator, the bulk elastic modulus of the hydraulic oil, the equivalent volume of the pipeline, and the displacement of the hydraulic motor, a coefficient matrix of the state equation of hydraulic PTO is established. The platform mass matrix, aerodynamic parameter matrix, and hydraulic PTO state equation coefficient matrix are divided into aerodynamic parameter vector, hydrodynamic parameter vector, and hydraulic parameter vector according to the physical domain. Based on the independent linearization analysis of each domain, the cross-domain parameter sensitivity coefficient is determined, and a cross-domain correlation constraint matrix is ​​established to obtain the multi-domain parameter initialization data package.

[0020] Specifically, the platform mass matrix is ​​a 6x6 matrix. Its diagonal elements correspond to the total platform mass in the three translational directions (swing, roll, and heave) and the moments of inertia in the three rotational directions (pitch, yaw, and yaw). The off-diagonal elements reflect the inertial coupling terms caused by the platform's center of mass offset, determined by the product of the center of mass coordinates and the total mass. The aerodynamic parameter matrix is ​​discretized at 0.5-meter intervals along the spanwise direction, based on blade elements. This 0.5-meter interval ensures that the changes in airfoil aerodynamic characteristics at each spanwise position are sufficiently distinguished, while keeping the number of computational nodes within an acceptable range for engineering applications. Too large an interval would increase the interpolation error of the lift and drag coefficients along the spanwise direction, while too small an interval would significantly increase the computational load of the BEM iteration. In the state equation coefficient matrix of hydraulic PTO, the bulk modulus of hydraulic oil characterizes the volumetric compressibility of hydraulic oil under pressure changes. Numerically, it is equal to the reciprocal of the volume change per unit volume of hydraulic oil under unit pressure. The equivalent volume of the pipeline is equivalent to a lumped parameter that represents the actual oil volume of the high-pressure chamber of the hydraulic cylinder, the connecting pipeline, and the accumulator inlet section. Both of these parameters together determine the response rate of the hydraulic cylinder pressure to the piston speed.

[0021] The construction process of the cross-domain correlation constraint matrix involves expanding the control equations of the aerodynamic, hydrodynamic, and hydraulic domains with respect to the system's rated operating point using a first-order Taylor expansion. Terms involving physical quantities from adjacent domains are extracted from each equation, and their partial derivatives with respect to adjacent domain parameters are used as sensitivity coefficients and filled into the corresponding positions in the matrix. The row indices correspond to the parameter numbers of the affected domain, and the column indices correspond to the parameter numbers of the domains to which the influence is applied. Initial values ​​are calculated under the combined conditions of rated wind speed and rated significant wave height. The aerodynamic parameter vector contains all blade aerodynamic parameters required by the BEM module; the hydrodynamic parameter vector contains hydrodynamic coefficients such as the platform mass matrix, additional mass matrix, and hydrostatic restoring force matrix required by the Cummins equations of motion; and the hydraulic parameter vector contains all hydraulic component parameters in the coefficient matrix of the hydraulic PTO state equation. These three types of vectors, along with the cross-domain correlation constraint matrix, are encapsulated into a multi-domain parameter initialization data package. This data package serves as a unified parameter source in subsequent steps and is directly called by the equations of each domain, avoiding the accumulation of coupling errors caused by inconsistent dimensional references when parameters are input independently.

[0022] In one specific embodiment, step S2 includes: Substitute the leaf element node coordinate vector in the multi-domain parameter initialization data package into the BEM module. Based on the platform sway velocity, platform pitch velocity and platform roll velocity, correct the equivalent inflow wind speed point by point according to the spanwise position and azimuth of each leaf element to obtain the equivalent inflow wind speed of each leaf element. The equivalent inflow velocity of each leaf element is input into the BEM module for iterative solution of axial and tangential induction factors. Based on the lift coefficient, drag coefficient and inflow angle of each leaf element, the normal force and tangential force of each leaf element are integrated to obtain the aerodynamic thrust and aerodynamic torque, which constitute the aerodynamic load vector. Substituting the platform mass matrix, infinite frequency additional mass matrix, hysteresis function matrix, and hydrostatic restoring force matrix from the multi-domain parameter initialization data package into the Cummins equation of motion, and taking the wave excitation force vector, mooring force vector, aerodynamic load vector, and hydraulic PTO reaction force vector as external force terms, the six-degree-of-freedom motion response of the platform is obtained. The platform pitch velocity in the six-degree-of-freedom motion response is fed back to the BEM module to update the equivalent inflow wind speed of the leaf element. The Cummins motion equation is then re-driven to iterate until the pitch velocity deviation between two adjacent steps is less than the convergence threshold, thus obtaining the converged six-degree-of-freedom motion response and aerodynamic load vector of the platform.

[0023] Specifically, the point-by-point correction of the equivalent inflow velocity for each blade element incorporates the three motion components of the platform: sway velocity, pitch velocity, and roll velocity. The platform sway velocity is directly subtracted from the free-flow velocity as the overall translational velocity component of the rotor. The influence of the platform pitch velocity on blade elements at different spanwise positions increases linearly with the product of the hub height and the sine of the spanwise position. The influence of the platform roll velocity on blade elements at different spanwise positions varies linearly with the cosine of the spanwise position. Both change periodically with the real-time azimuth angle of the blade element. Therefore, the velocity correction amount varies for the same spanwise position at different azimuth angles, and the equivalent inflow velocities of the upper and lower blade elements deviate in opposite directions. The iterative convergence criterion for the axial induction factor and the tangential induction factor is set as the deviation between two adjacent iterations being less than... This value ensures that the aerodynamic calculation accuracy meets engineering requirements while controlling the number of iterations within a reasonable range. Excessive deviation will transfer the aerodynamic thrust integration error to the hydrodynamic domain, while insufficient deviation will significantly increase the number of iterations with limited accuracy improvement. The normal force of each blade element is determined by the sum of the projections of the lift component onto the inflow plane and the drag component onto the inflow plane. The tangential force is determined by the difference between the projections of the lift component onto the tangential direction of the rotation plane and the drag component onto the tangential direction of the rotation plane. The aerodynamic thrust and aerodynamic torque are obtained by integrating the normal and tangential forces of all blade elements along the spanwise direction and multiplying by the number of blades.

[0024] The infinite-frequency added mass matrix characterizes the additional inertial effect of the fluid on the platform motion under infinitely high-frequency excitation. Its value is given by the added mass limit value of frequency-domain hydrodynamic analysis as the frequency approaches infinity. The hysteresis function matrix transforms the radiation damping effect within a finite frequency range into a time-domain convolution term, reflecting the cumulative influence of the platform's motion history on the current radiation force. The hydraulic PTO reaction force vector is incorporated into the Cummins equation of motion in the form of an explicit external force term, rather than treating the PTO force as an equivalent additional damping coefficient as in existing technologies. The difference lies in the fact that the explicit treatment method retains the nonlinear characteristics of the real-time change of hydraulic cylinder pressure with piston displacement, so that the platform motion response includes the additional motion component caused by hydraulic pulsation. The convergence criterion for the pneumatic-hydraulic bidirectional iteration is that the deviation of the pitch angular velocity between two adjacent steps is less than 1. The threshold corresponds to the acceptable calculation accuracy of the platform pitch motion. The pitch angular velocity deviation directly determines the change range of the equivalent inflow wind speed correction of the blade element. Using this amount as a convergence criterion can ensure that the calculation error of the aerodynamic load vector after iterative convergence is within the allowable deviation range of the blade aerodynamic design load.

[0025] In one specific embodiment, step S3 includes: Based on the platform heave displacement and platform pitch angle in the platform's six-degree-of-freedom motion response, the absolute heave displacement of each WEC float is corrected according to the horizontal distance of each WEC float from the platform center, so as to obtain the relative heave displacement and relative heave velocity of each WEC float relative to the platform. Substituting the relative heave velocity and the hydraulic cylinder piston area, hydraulic oil bulk elastic modulus and leakage coefficient in the hydraulic PTO state equation coefficient matrix into the hydraulic PTO nonlinear pressure-flow dynamic equation, and describing the accumulator gas compression process with an adiabatic process equation, we obtain the hydraulic cylinder high-pressure chamber pressure time series corresponding to each WEC float. The average value of the pressure time series of the high-pressure chamber of the hydraulic cylinder is calculated within the sliding time window. The pressure of the high-pressure chamber of each WEC float is subtracted from its corresponding average value. The main frequency of the pulsation is determined by fast Fourier transform, and the pressure pulsation feature vector is obtained. Based on the time series of high-pressure chamber pressure, low-pressure chamber pressure, piston mass, and sealing friction damping coefficient of the hydraulic cylinder, the hydraulic cylinder constraint force of each WEC float is solved. The required constraint force is applied to the platform in the form of equal magnitude and opposite direction to obtain the hydraulic PTO reaction force vector.

[0026] Specifically, the absolute heave displacement of each WEC float is obtained by solving the hydrodynamic equations for each WEC float individually. The correction for the relative heave displacement is to subtract the absolute heave displacement of the WEC float from the sum of the platform heave displacement multiplied by the platform pitch angle multiplied by the horizontal distance of the WEC float from the platform center. The product of the platform pitch angle and the horizontal distance reflects the vertical displacement component generated at each WEC mounting point when the platform rotates around the pitch axis. This component increases linearly with the increase of the distance of the WEC float from the platform center. Ignoring this term will lead to a systematic overestimation of the relative motion amplitude of the WEC floats arranged at the platform edge. The relative heave velocity is obtained by taking the first derivative of the relative heave displacement with respect to time. When substituting it into the nonlinear pressure-flow dynamic equation of the hydraulic PTO, the high-pressure chamber volume is taken as the sum of the initial volume of the hydraulic cylinder and the piston area multiplied by the relative heave displacement. This volume changes in real time with the relative heave displacement, which is one of the main sources of nonlinearity in the equation. The leakage coefficient characterizes the proportional relationship between the internal leakage flow rate and the pressure difference between the high-pressure and low-pressure chambers of the hydraulic cylinder due to the sealing gap. Its value is determined by the sealing material and fitting precision of the hydraulic cylinder. In the equation, it appears as a negative correction term for the rate of change of the high-pressure chamber volume, in the form of pressure difference multiplied by the leakage coefficient. The gas compression of the accumulator is described by an adiabatic process equation, with an adiabatic index of 1.4. This value corresponds to the standard adiabatic index value of nitrogen under rapid compression conditions. The motion cycle of a floating platform under wave excitation is typically in the range of 5 to 20 seconds. The gas compression rate is much higher than the time scale required for sufficient heat exchange between the gas and the environment. Therefore, the adiabatic assumption is more consistent with actual working conditions than the isothermal assumption.

[0027] The sliding time window width is set to 10 seconds, which covers the main energy concentration period range of the heave motion of the floating platform. Within this window, the low-frequency trend term is obtained by averaging the high-pressure chamber pressure time series. The pressure pulsation quantity after removing the low-frequency trend is obtained by subtracting the real-time pressure from the mean. When performing a fast Fourier transform on this pulsation quantity, it is regarded as a sample of a stationary random signal within the window. The frequency component with the largest amplitude in the transform result is the pulsation master frequency. The pulsation master frequency and the corresponding pulsation amplitude of each WEC float are arranged in order of WEC number to form a pressure pulsation feature vector, and the vector dimension is equal to twice the number of WEC floats. The hydraulic cylinder constraint force is composed of three factors: the difference between the high-pressure chamber pressure and the low-pressure chamber pressure multiplied by the piston area, the piston mass multiplied by the relative acceleration, and the sealing friction damping coefficient multiplied by the relative heave velocity. The low-pressure chamber pressure is taken as the back pressure value on the low-pressure side of the hydraulic circuit, and the sealing friction damping coefficient reflects the viscous friction characteristics between the piston and the cylinder wall. The constraint force acts on the corresponding mounting point of the platform in the form of equal magnitude and opposite direction according to Newton's third law. After being converted into a six-component generalized force in the platform coordinate system, it constitutes the hydraulic PTO reaction force vector. The generalized force components contributed by each WEC float are superimposed according to the mounting point position.

[0028] Figure 2This is a schematic diagram of the fast Fourier transform spectrum of pressure pulsation in the high-pressure chamber of the hydraulic cylinder in an embodiment of this application. Figure 2 The figure shows the frequency domain amplitude distribution obtained after performing a fast Fourier transform on the pressure pulsation. The horizontal axis represents frequency, and the vertical axis represents the pressure pulsation amplitude corresponding to each frequency component. The amplitude is largest at the main pulsation frequency of 0.117Hz, which corresponds to the main energy concentration frequency of the WEC float's heave motion under the current sea state. This frequency and the corresponding pulsation amplitude together constitute the component of the WEC float in the pressure pulsation characteristic vector. Subsequently, the platform transfer function matrix is ​​multiplied by the frequency domain component of the hydraulic PTO reaction force at this frequency to complete the first-stage reverse coupling transfer from the hydraulic domain to the hydrodynamic domain.

[0029] In one specific embodiment, step S4, mapping the pressure pulsation feature vector to an additional platform pitch motion component via a platform transfer function, includes: Based on the pulsating main frequency of each WEC float in the pressure pulsation feature vector, the hydraulic PTO reaction force vector is Fourier transformed at each pulsating main frequency to obtain the frequency domain components of the hydraulic PTO reaction force at each pulsating main frequency. The frequency domain component of the hydraulic PTO reaction force is input into the platform transfer function matrix. The transfer function value at each pulsating main frequency is multiplied by the frequency domain component of the hydraulic PTO reaction force at each frequency point to obtain the additional motion frequency domain response of the platform at each pulsating main frequency. The additional pitch motion component of the platform is obtained by superimposing the platform's additional motion frequency domain response with the pulsating main frequencies corresponding to all WEC floats and then performing an inverse Fourier transform.

[0030] Specifically, the platform transfer function matrix is ​​obtained by inverting the coefficient matrix of the Cummins equations of motion in the frequency domain. The derivation involves transforming the time-domain convolution terms in the Cummins equations of motion into frequency-domain multiplications. The frequency-domain expressions of the mass matrix, additional mass matrix, and hysteresis function matrix on the left-hand side of the equations are combined with the hydrostatic restoring force matrix to form the system impedance matrix. Inverting this impedance matrix yields the platform transfer function matrix. Its physical meaning is the amplitude and phase response of the platform's six degrees of freedom motion caused by a unit-amplitude harmonic external force at a specific frequency. The matrix has a dimension of six rows and six columns, with row subscripts corresponding to the six degrees of freedom of the platform and column subscripts corresponding to the six generalized external force directions. The frequency-domain components of the hydraulic PTO reaction force vector at each pulsation master frequency are obtained by performing a discrete Fourier transform on the reaction force vector time series and taking the corresponding complex spectral values ​​at each pulsation master frequency given by the pressure pulsation characteristic vector. These complex spectral values ​​simultaneously contain amplitude and phase information. When multiplying with the transfer function matrix, complex number operations are retained to ensure the correct transmission of phase relationships.

[0031] The platform's additional motion frequency domain response at each pulsed main frequency is given by the matrix-vector product of the transfer function matrix and the hydraulic PTO reaction force frequency domain component, resulting in a six-dimensional complex vector, corresponding to the additional motion amplitude and phase of the platform's six degrees of freedom at that frequency. The platform's additional motion frequency domain responses at all pulsed main frequencies corresponding to the WEC floats are linearly superimposed in the frequency domain, and the superposition result constitutes a sparse spectrum. This spectrum has non-zero values ​​only at each pulsed main frequency. Performing an inverse Fourier transform on this sparse spectrum yields the time series of the six components of the platform's additional motion in the time domain. Extracting the pitch direction component from this time series gives the platform's additional pitch motion component. The operation of extracting the pitch direction component corresponds to taking the fifth component of the six-dimensional time domain vector. This component corresponds to the rotational motion of the platform around the horizontal axis. In the floating hybrid wind and wave power generation system, the pitch motion has the most significant impact on the equivalent inflow wind speed of the wind turbine. This is because the pitch motion causes the wind turbine sweep surface to tilt forward and backward as a whole, resulting in a reverse deviation in the inflow velocity between the upper and lower blade elements. The magnitude of this deviation increases linearly with the spanwise position and is the dominant transmission path of the hydraulic pulsating load affecting the aerodynamic domain through the platform motion.

[0032] In one specific embodiment, step S4, which converts the platform's additional pitch motion component into a leaf-by-leaf equivalent inflow wind speed correction based on spanwise position, includes: The additional pitch motion component of the platform is derived by taking the time derivative, and the additional pitch angular velocity of the platform is obtained. Substitute the platform's additional pitch angular velocity, hub height, spanwise position of each blade element, and real-time azimuth angle of each blade element into the blade element velocity projection formula, and calculate the velocity contribution of each blade element's spanwise position and azimuth angle to the platform's additional pitch angular velocity point by point to obtain the velocity deviation at each blade element caused by hydraulic pulsation. The velocity deviations caused by hydraulic pulsation at each leaf element are summarized to obtain the equivalent inflow wind speed correction for each leaf element.

[0033] Specifically, the time derivative of the platform's additional pitch motion component is calculated using the central difference scheme. That is, the difference between the additional pitch motion component at the current time step and the time steps before and after it is divided by twice the time step size to obtain the platform's additional pitch angular velocity at the current moment. The time step size is consistent with the integration step size of the Cummins equation of motion, which is 0.05 seconds. This step size satisfies the Nyquist sampling theorem requirement within the main motion frequency range of the floating platform, ensuring that the numerical differentiation result does not introduce additional frequency aliasing error. The geometric derivation of the velocity projection relationship of each blade element is based on rigid body kinematics. When the platform rotates around the pitch axis at an angular velocity, the projection of the velocity component of any point in the wind turbine sweep surface onto the wind turbine axis is obtained by multiplying the vertical distance from that point to the pitch axis by the pitch angular velocity. The vertical distance from the hub center to the pitch axis is the hub height. The vertical distance from the blade element node to the hub center is the spanwise position multiplied by the sine of the real-time azimuth angle of that blade element. The sum of the two constitutes the total vertical distance from the blade element node to the pitch axis. Multiplying this by the additional pitch angular velocity of the platform yields the velocity deviation along the wind turbine axis at that blade element. The negative sign indicates that when the platform tilts forward, the direction of this velocity deviation is opposite to the direction of the incoming flow.

[0034] The real-time azimuth angle of each blade element is defined as the angle through which the blade containing the blade element rotates from its vertically upward position along the direction of rotor rotation. The value ranges from 0 to 2π, and it is updated at each time step by integrating the real-time rotor speed with the time step. The blade element located at an azimuth angle of 90 degrees has the largest vertical distance from the pitch axis, corresponding to the largest velocity deviation amplitude. The blade element located at an azimuth angle of 270 degrees has a negative vertical distance, and its velocity deviation direction is opposite to that at 90 degrees. The vertical distance contribution of blade elements located at azimuth angles of 0 degrees or 180 degrees comes only from the hub height term. The velocity deviation of each blade element varies periodically with the sine value of the azimuth angle, forming a periodic non-uniform inflow disturbance at one times the rotor frequency. The velocity deviation caused by hydraulic pulsation at each blade element is organized into a column vector according to the arrangement order of the blade element node coordinate vector. The total dimension of the vector is equal to the product of the number of blades and the number of blade elements per blade. This vector is the equivalent inflow velocity correction for each blade element. Each element corresponds to the equivalent inflow velocity deviation value of a blade element transmitted to the aerodynamic domain by the platform pitch motion due to hydraulic pulsation at the current time step. This value strictly corresponds to the blade element numbering order used by the BEM module in step S2 when calculating the equivalent inflow velocity for each blade element.

[0035] In one specific embodiment, in step S4, the equivalent inflow wind speed correction of the leaf element is converted into a pitch feedforward compensation angle via the blade root bending moment sensitivity matrix. The pitch feedforward compensation angle is then superimposed with the feedback pitch command to obtain a comprehensive pitch command, including: Based on the aerodynamic parameter matrix in the multi-domain parameter initialization data package, linearization analysis is performed on each blade under rated wind speed conditions. The diagonal elements of the blade root bending moment sensitivity matrix are determined for each blade according to the optimal pitch angle adjustment corresponding to the unit equivalent inflow wind speed change, and the blade root bending moment sensitivity matrix is ​​obtained. The equivalent inflow wind speed correction of each leaf element is input into the blade root bending moment sensitivity matrix. The equivalent inflow wind speed correction of each leaf element is multiplied by the diagonal elements of each leaf element and the negative sign is obtained to obtain the pitch feedforward compensation angle. The pitch feedforward compensation angle and the feedback pitch command are superimposed one-to-one according to the blade to obtain the comprehensive pitch command, thus completing the three-level reverse coupling correction between the hydraulic domain, hydrodynamic domain and aerodynamic control domain.

[0036] Specifically, the diagonal elements of the blade root moment sensitivity matrix are determined through the following linearization process: Under rated wind speed conditions, the airfoil lift coefficient, drag coefficient, and blade element chord length of each blade in the aerodynamic parameter matrix are substituted into the BEM module. A unit positive disturbance is applied to the equivalent inflow wind speed near the current rated pitch angle reference value, and the change in blade root moment is recorded. Then, a unit positive disturbance is applied to the pitch angle, and the change in blade root moment with the pitch angle is recorded. The ratio of the two is the diagonal element of the blade root moment sensitivity matrix, in degrees per second (m / s). Physically, it represents the optimal pitch angle compensation required to offset the change in blade root moment caused by the unit equivalent inflow wind speed disturbance. The basis for taking the diagonal form of the matrix is ​​that the aerodynamic parameters of the three blades are symmetrical under rated conditions, and the equivalent inflow wind speed disturbance of each blade only has a significant impact on the blade root moment of that blade. The aerodynamic interference effect across blades is negligible within the engineering accuracy range, therefore, the off-diagonal elements are set to zero.

[0037] The physical basis for multiplying the equivalent inflow velocity correction of a blade by its diagonal elements and taking a negative sign is that when the equivalent inflow velocity of a blade increases positively due to hydraulic pulsation, the aerodynamic thrust of that blade also increases. To offset this increase, the pitch angle needs to be adjusted in the direction of increase to increase aerodynamic drag and reduce thrust. The feedforward compensation corresponding to the direction of increasing pitch angle is positive, and the equivalent inflow velocity correction is also positive. Taking a negative sign for the product of the two results in a negative compensation angle, which contradicts this relationship. Therefore, the actual source of the negative sign is the coordinate system definition: the equivalent inflow velocity correction is defined as the reduction relative to the free flow. A positive correction indicates a decrease in inflow velocity, and the pitch controller needs to reduce the pitch angle to maintain aerodynamic torque. The corresponding feedforward compensation angle is negative, and taking a negative sign aligns with the direction of decrease. The feedback pitch command is generated by the conventional gain-controlled proportional-integral controller based on the generator speed deviation. The integrated pitch command is obtained by adding the feedforward compensation angle and the feedback pitch command according to the blade number. After being sent to the pitch actuator of each blade, the disturbance path from hydraulic pulsation to the aerodynamic domain through the platform pitch motion is cut off by the feedforward compensation. The three-level reverse coupling correction between the hydraulic domain, hydrodynamic domain and aerodynamic control domain forms a complete closed loop within this time step. The Cummins equation of motion in the next time step continues to advance with the aerodynamic load vector updated by the integrated pitch command as input.

[0038] The above describes the multi-domain coupling analysis method for the floating hybrid wind and wave power generation system in the embodiments of this application. The following describes the multi-domain coupling analysis system for the floating hybrid wind and wave power generation system in the embodiments of this application. One embodiment of the multi-domain coupling analysis system for the floating hybrid wind and wave power generation system in the embodiments of this application includes: The analysis module is used to establish a multi-domain parameter initialization data package based on the structural parameters of the floating hybrid wind and wave power generation system and the parameters of the hydraulic PTO system; The calculation module is used to substitute the multi-domain parameter initialization data package into the Cummins motion equation and the BEM module to obtain the platform's six-degree-of-freedom motion response and aerodynamic load vector. The generation module is used to substitute the six-degree-of-freedom motion response of the platform into the nonlinear pressure-flow dynamic equation of the hydraulic PTO to obtain the pressure pulsation characteristic vector and the hydraulic PTO reaction force vector. The correction module is used to map the pressure pulsation feature vector into an additional pitch motion component of the platform via the platform transfer function, convert the additional pitch motion component into a leaf element equivalent inflow wind speed correction amount according to the spanwise position, convert the leaf element equivalent inflow wind speed correction amount into a pitch feedforward compensation angle via the blade root bending moment sensitivity matrix, and superimpose the pitch feedforward compensation angle with the feedback pitch command to obtain a comprehensive pitch command, thus completing the three-level reverse coupling correction between the hydraulic domain, hydrodynamic domain and aerodynamic control domain.

[0039] This invention also provides a multi-domain coupling analysis device for a floating hybrid wind and wave power generation system, which can be a server. The device includes a processor, memory, display screen, input device, network interface, and database connected via a system bus. The processor, designed as a computer, provides computational and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The database stores the data corresponding to this embodiment. The network interface communicates with external terminals via a network connection. When the computer program is executed by the processor, it implements the above-described method.

[0040] The present invention also provides a computer-readable storage medium, which can be a non-volatile computer-readable storage medium or a volatile computer-readable storage medium, wherein the computer-readable storage medium stores instructions that, when the instructions are executed on a computer, cause the computer to perform the steps of the multi-domain coupling analysis method for the floating hybrid wind and wave power generation system.

[0041] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0042] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a floating hybrid wind and wave power generation system multi-domain coupling analysis device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0043] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-domain coupling analysis method for a floating hybrid wind and wave power generation system, characterized in that, The method includes: Step S1: Based on the structural parameters of the floating hybrid wind and wave power generation system and the parameters of the hydraulic PTO system, establish a multi-domain parameter initialization data package; Step S2: Substitute the multi-domain parameter initialization data package into the Cummins motion equation and BEM module to obtain the platform's six-degree-of-freedom motion response and aerodynamic load vector. Step S3: Substitute the six-degree-of-freedom motion response of the platform into the nonlinear pressure-flow dynamic equation of the hydraulic PTO to obtain the pressure pulsation characteristic vector and the hydraulic PTO reaction force vector. Step S4: The pressure pulsation feature vector is mapped to the platform additional pitch motion component through the platform transfer function. The platform additional pitch motion component is converted into the equivalent inflow wind speed correction amount of the leaf element according to the spanwise position. The equivalent inflow wind speed correction amount of the leaf element is converted into the pitch feedforward compensation angle through the blade root bending moment sensitivity matrix. The pitch feedforward compensation angle is superimposed with the feedback pitch command to obtain the comprehensive pitch command, thus completing the three-level reverse coupling correction between the hydraulic domain, hydrodynamic domain and aerodynamic control domain.

2. The multi-domain coupling analysis method for floating hybrid wind and wave power generation systems according to claim 1, characterized in that, Step S1 includes: Based on the total mass, center of mass coordinates, six-degree-of-freedom rotational inertia matrix, displacement volume, and waterline area of ​​the floating semi-submersible platform, a platform mass matrix is ​​established. The rated rotational speed, blade radius, rated wind speed, and lift and drag coefficient data at each spanwise position of the wind turbine blades are written into the aerodynamic parameter matrix of the BEM module. The spanwise nodes are discretized according to the blade element spacing to obtain the blade element node coordinate vector. Based on the piston area of ​​the hydraulic cylinder, the pre-charge pressure of the hydraulic accumulator, the bulk elastic modulus of the hydraulic oil, the equivalent volume of the pipeline, and the displacement of the hydraulic motor, a coefficient matrix of the state equation of hydraulic PTO is established. The platform mass matrix, the aerodynamic parameter matrix, and the hydraulic PTO state equation coefficient matrix are divided into aerodynamic parameter vectors, hydrodynamic parameter vectors, and hydraulic parameter vectors according to the physical domain. Based on the independent linearization analysis of each domain, the cross-domain parameter sensitivity coefficients are determined, and a cross-domain correlation constraint matrix is ​​established to obtain a multi-domain parameter initialization data package.

3. The multi-domain coupling analysis method for floating hybrid wind and wave power generation systems according to claim 2, characterized in that, Step S2 includes: Substitute the leaf element node coordinate vector in the multi-domain parameter initialization data packet into the BEM module. Based on the platform sway velocity, platform pitch velocity and platform roll velocity, correct the equivalent inflow wind speed point by point according to the spanwise position and azimuth of each leaf element to obtain the equivalent inflow wind speed of each leaf element. The equivalent inflow velocity of each leaf element is input into the BEM module for iterative solution of axial and tangential induction factors. Based on the lift coefficient, drag coefficient and inflow angle of each leaf element, the normal force and tangential force of each leaf element are integrated to obtain the aerodynamic thrust and aerodynamic torque, which constitute the aerodynamic load vector. Substituting the platform mass matrix, infinite frequency additional mass matrix, hysteresis function matrix and hydrostatic restoring force matrix from the multi-domain parameter initialization data package into the Cummins equation of motion, and taking the wave excitation force vector, mooring force vector, the aerodynamic load vector and the hydraulic PTO reaction force vector as external force terms, the six-degree-of-freedom motion response of the platform is obtained. The platform pitch velocity in the six-degree-of-freedom motion response is fed back to the BEM module to update the equivalent inflow wind speed of the leaf element. The Cummins motion equation is then re-driven to iterate until the pitch velocity deviation between two adjacent steps is less than the convergence threshold, thus obtaining the converged six-degree-of-freedom motion response and aerodynamic load vector of the platform.

4. The multi-domain coupling analysis method for floating hybrid wind and wave power generation systems according to claim 3, characterized in that, Step S3 includes: Based on the platform heave displacement and platform pitch angle in the platform's six-degree-of-freedom motion response, the absolute heave displacement of each WEC float is corrected according to the horizontal distance of each WEC float from the platform center, so as to obtain the relative heave displacement and relative heave velocity of each WEC float relative to the platform. Substitute the relative heave velocity and the hydraulic cylinder piston area, hydraulic oil bulk elastic modulus and leakage coefficient in the hydraulic PTO state equation coefficient matrix into the hydraulic PTO nonlinear pressure-flow dynamic equation, and describe the accumulator gas compression process with an adiabatic process equation to obtain the hydraulic cylinder high pressure chamber pressure time series corresponding to each WEC float. The average value of the pressure time series of the high-pressure chamber of the hydraulic cylinder is calculated within the sliding time window. The pressure of the high-pressure chamber of each WEC float is subtracted from its corresponding average value. The main frequency of the pulsation is determined by fast Fourier transform, and the pressure pulsation feature vector is obtained. Based on the high-pressure chamber pressure time series, low-pressure chamber pressure, piston mass, and sealing friction damping coefficient of the hydraulic cylinder, the hydraulic cylinder constraint force of each WEC float is solved. The calculated constraint force is applied to the platform in the form of equal magnitude and opposite direction to obtain the hydraulic PTO reaction force vector.

5. The multi-domain coupling analysis method for floating hybrid wind and wave power generation systems according to claim 1, characterized in that, In step S4, the pressure pulsation feature vector is mapped to an additional pitch motion component of the platform via a platform transfer function, including: Based on the pulsation main frequency of each WEC float in the pressure pulsation feature vector, the hydraulic PTO reaction force vector is subjected to Fourier transform at each pulsation main frequency to obtain the hydraulic PTO reaction force frequency domain component at each pulsation main frequency. The frequency domain component of the hydraulic PTO reaction force is input into the platform transfer function matrix. The transfer function value at each pulsating main frequency is multiplied by the frequency domain component of the hydraulic PTO reaction force at each frequency point to obtain the additional motion frequency domain response of the platform at each pulsating main frequency. The additional pitch motion component of the platform is obtained by superimposing the frequency domain response of the platform with the pulsating main frequencies corresponding to all WEC floats and then performing an inverse Fourier transform.

6. The multi-domain coupling analysis method for a floating hybrid wind and wave power generation system according to claim 5, characterized in that, In step S4, the additional pitch motion component of the platform is converted into an equivalent inflow wind speed correction amount based on the spanwise position, including: The additional pitch angular velocity of the platform is obtained by taking the time derivative of the additional pitch motion component of the platform. Substitute the platform's additional pitch angular velocity, hub height, spanwise position of each blade element, and real-time azimuth angle of each blade element into the blade element velocity projection formula, and calculate the velocity contribution of each blade element's spanwise position and azimuth angle to the platform's additional pitch angular velocity point by point to obtain the velocity deviation at each blade element caused by hydraulic pulsation. The velocity deviations caused by hydraulic pulsation at each leaf element are summarized to obtain the equivalent inflow wind speed correction for each leaf element.

7. The multi-domain coupling analysis method for a floating hybrid wind and wave power generation system according to claim 6, characterized in that, In step S4, the equivalent inflow wind speed correction of the leaf element is converted into a pitch feedforward compensation angle via the blade root bending moment sensitivity matrix. The pitch feedforward compensation angle is then superimposed with the feedback pitch command to obtain a comprehensive pitch command, including: Based on the aerodynamic parameter matrix in the multi-domain parameter initialization data packet, linearization analysis is performed on each blade under rated wind speed conditions. The diagonal elements of the blade root bending moment sensitivity matrix are determined for each blade according to the optimal pitch angle adjustment amount corresponding to the unit equivalent inflow wind speed change, and the blade root bending moment sensitivity matrix is ​​obtained. The equivalent inflow wind speed correction of the leaf element is input into the blade root bending moment sensitivity matrix. The equivalent inflow wind speed correction of the leaf element is multiplied by the diagonal element of each leaf and the negative sign is taken to obtain the pitch feedforward compensation angle. The pitch feedforward compensation angle and the feedback pitch command are superimposed one-to-one according to the blade to obtain the comprehensive pitch command, thus completing the three-level reverse coupling correction between the hydraulic domain, hydrodynamic domain and aerodynamic control domain.

8. A multi-domain coupling analysis system for a floating hybrid wind and wave power generation system, characterized in that, A method for implementing the multi-domain coupling analysis of a floating hybrid wind-wave power generation system as described in any one of claims 1-7, wherein the multi-domain coupling analysis system for the floating hybrid wind-wave power generation system comprises: The analysis module is used to establish a multi-domain parameter initialization data package based on the structural parameters of the floating hybrid wind and wave power generation system and the parameters of the hydraulic PTO system; The calculation module is used to substitute the multi-domain parameter initialization data package into the Cummins motion equation and the BEM module to obtain the platform's six-degree-of-freedom motion response and aerodynamic load vector. The generation module is used to substitute the six-degree-of-freedom motion response of the platform into the nonlinear pressure-flow dynamic equation of the hydraulic PTO to obtain the pressure pulsation characteristic vector and the hydraulic PTO reaction force vector. The correction module is used to map the pressure pulsation feature vector into an additional pitch motion component of the platform via the platform transfer function, convert the additional pitch motion component into a leaf element equivalent inflow wind speed correction amount according to the spanwise position, convert the leaf element equivalent inflow wind speed correction amount into a pitch feedforward compensation angle via the blade root bending moment sensitivity matrix, and superimpose the pitch feedforward compensation angle with the feedback pitch command to obtain a comprehensive pitch command, thus completing the three-level reverse coupling correction between the hydraulic domain, hydrodynamic domain and aerodynamic control domain.

9. A multi-domain coupling analysis device for a floating hybrid wind and wave power generation system, characterized in that, The system includes a memory and a processor, wherein the memory stores a computer program that can run on the processor, and the processor executes the computer program to implement the multi-domain coupling analysis method for the floating hybrid wind and wave power generation system as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is run by the processor, it causes the processor to execute the multi-domain coupling analysis method for the floating hybrid wind and wave power generation system as described in any one of claims 1 to 7.

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