FLNG-LNGC combined loading and unloading operation control method and system based on real-time working condition feedback

Abstract

The invention discloses an FLNG-LNGC combined loading and unloading operation control method and system based on real-time working condition feedback, and the method comprises the steps: firstly constructing a system state space with time-space synchronization, and collecting the time calendar of a wave field and the motion response of a ship body; and reconstructing an instantaneous wave energy spectrum, resolving ship body modal parameters, and calculating a frequency detuning safety factor. When the resonance risk exists, the system executes asymmetric loading path planning based on frequency detuning optimization, and the rotational inertia of the ship body is changed by adjusting cabin flow distribution so as to shift the inherent frequency; and meanwhile, a gas-liquid coupling active suppression instruction containing variable stiffness pressure modulation and pulse momentum damping is generated, the recovery stiffness is changed through gas phase pressure, and damping torque is generated through fluid momentum. And finally, the instructions are synthesized to drive an execution mechanism. Active regulation and control of ship body modal frequency and instant dissipation of wave disturbance are achieved, the resonance risk is effectively reduced, and the stability of double-ship operation under the severe sea condition is improved.

Description

Technical Field

[0001] This invention belongs to the field of marine engineering and ship motion control technology, and particularly relates to a control method and system for FLNG-LNGC joint loading and unloading operations based on real-time operating condition feedback. Background Technology

[0002] When floating liquefied natural gas production storage and offloading (FLNG) units and liquefied natural gas carriers (LNGCs) conduct gantry loading and unloading operations in open waters, they face complex marine environmental disturbances. The two-ship system is not only affected by external environmental loads such as wind, waves, and currents, but also by the mutual hydrodynamic interference between the hulls and the coupling effect caused by the sloshing of liquid cargo within the holds. To ensure operational safety, controlling the relative motion of the two ships and maintaining the stability of the hull structure are core requirements of the operational system.

[0003] Current liquid cargo loading and unloading control strategies primarily rely on pre-defined loading manuals or stowage plans. These plans are typically based on hydrostatic calculations, focusing on meeting the ship's longitudinal strength, shear force, and static stability requirements. Loading paths are often set as symmetrical, uniform, or linear flows following a fixed sequence. However, LNG carriers are typical variable-mass systems during loading, and changes in their mass distribution directly cause drift in the ship's natural frequencies. In actual operations, the wave spectrum characteristics change over time. When the ship's instantaneous natural frequency couples with the dominant wave frequency band, resonance is easily triggered, leading to a sharp increase in the ship's motion amplitude. Existing static stowage strategies lack the ability to perceive and adjust this dynamic frequency matching relationship in real time, and cannot avoid resonance bands by actively changing the mass distribution path.

[0004] Furthermore, current technologies for suppressing ship motion primarily rely on external mooring systems or tugboat assistance, neglecting the dynamic potential of the cargo transfer system itself. In conventional control logic, the flow rate of the cargo transfer pipeline is set to a constant value or a simple stepped variation, and the internal gas pressure is maintained within a constant safety range. This control method treats cargo transfer merely as a simple material transport process, failing to utilize the momentum flux generated during high-speed fluid injection and the compressibility of the gas phase space as active control forces. This means that when facing high-frequency wave disturbances, the internal fluid transfer system cannot provide damping or stiffness compensation for ship motion; in fact, the sloshing of liquid within the tanks may exacerbate the ship's rolling and heaving motions, limiting the operational window in adverse sea conditions. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a control method and system for FLNG-LNGC joint loading and unloading operations based on real-time operating condition feedback. This solves the problem of amplified resonance response caused by the coupling of ship hull modal frequency drift and wave excitation frequency during the variable mass process of liquid cargo transfer between floating liquefied natural gas production, storage and unloading units and transport vessels.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A control method for FLNG-LNGC joint loading and unloading operations based on real-time operating condition feedback includes the following steps: Environmental excitation parameters and ship loading status parameters are collected at the work site to construct a spatiotemporally synchronized system state space containing wave history data, ship motion response data, and compartment fluid distribution data. Based on the wave history data, the instantaneous wave energy spectrum is reconstructed, and the ship's instantaneous natural frequency is calculated based on the compartment fluid distribution data. A frequency detuning safety factor is calculated between the ship's instantaneous natural frequency and the peak frequency of the instantaneous wave energy spectrum. When the frequency detuning safety factor is lower than a preset threshold, an asymmetric loading command is generated. This asymmetric loading command is used to change the ship's instantaneous natural frequency by adjusting the flow distribution of each cargo tank, thereby increasing the frequency difference between it and the peak frequency. Based on the ship motion response data, an active suppression command is generated. This active suppression command includes at least a variable stiffness pressure modulation command for adjusting the pressure in the cargo tank's gas phase space and / or a pulse momentum damping command for superimposing periodic pulsating components onto a reference loading flow rate. The asymmetric loading command and the active suppression command are synthesized to generate a general control command that drives the actuators of the cargo transfer system.

[0007] Furthermore, the construction of the spatiotemporally synchronized system state space includes: Wave history data is acquired using non-contact sea surface measurement equipment, six-degree-of-freedom motion response data of the hull is collected using an inertial measurement unit, and fluid distribution data of the compartments is acquired through a liquid level and pressure monitoring system. The fluid distribution data of the compartments includes at least the fluid mass and center of mass position of each compartment. Wave history data, six-degree-of-freedom motion response data of the hull, and fluid distribution data from different sampling frequencies are unified to the same time reference axis through a time synchronization algorithm to form a system state vector.

[0008] Furthermore, the calculation of the ship's instantaneous natural frequency includes: Based on the fluid mass and center of mass position of each compartment at the current moment, combined with the empty ship mass distribution and its pitching moment of inertia, the parallel axis theorem is applied to calculate the total pitching moment of inertia of the entire ship at the current moment. Calculate the pitch recovery stiffness coefficient based on the current hull draft and waterline area; The instantaneous natural frequency of the hull is calculated based on the total pitch inertia and the pitch recovery stiffness coefficient.

[0009] Furthermore, the generation of asymmetric load instructions includes: With the optimization objective of maximizing the frequency difference between the instantaneous natural frequency and the peak frequency of the hull at the next prediction time, and with the constraints of total flow conservation, pipeline valve capacity, and hull strength and stability, a nonlinear programming model is established. Solve the nonlinear programming model to obtain the optimal flow allocation vector, and generate a control sequence that includes the liquid inlet timing and flow rate of each liquid cargo tank based on the optimal flow allocation vector.

[0010] Furthermore, the process of solving the optimization objective includes: prioritizing the allocation of flow to the bow and stern compartments of the hull to reduce the instantaneous natural frequency of the hull, or prioritizing the allocation of flow to the midship compartments of the hull to increase the instantaneous natural frequency of the hull.

[0011] Furthermore, the generation of variable stiffness pressure modulation commands specifically includes: Based on the real-time displacement and phase of the ship's vertical motion, and according to the preset pressure modulation control law, the target pressure setpoint of the liquid cargo tank's gas phase space is dynamically calculated and output. The pressure modulation control law is:

[0012] in, The setpoint for the gas phase space pressure at time t. As the benchmark operating pressure, This is the pressure modulation gain coefficient. Let be the vertical displacement of the ship's hull at time t.

[0013] Furthermore, the aforementioned command for generating pulse momentum damping is specifically as follows: Above the baseline flow rate of each compartment determined by the asymmetric loading command, a periodic pulsating component with a preset modulation amplitude and phase lead angle, opposite in phase to the hull roll motion, is superimposed to form a total target flow rate signal with damping effect; the periodic pulsating component is generated according to the following control law:

[0014] in, Let be the mass flow rate at time t. As the baseline flow rate, For modulation amplitude, Let be the roll phase at time t. This is the phase lead angle.

[0015] Furthermore, the synthesis instructions include: The reference flow rate of each compartment determined by the asymmetric loading command is superimposed with the periodic pulsation component determined by the pulse momentum damping command to synthesize the final total target flow rate signal of each liquid cargo tank. The target pressure setting value determined by the variable stiffness pressure modulation command is used as the setting value of the gas phase pressure control loop.

[0016] Furthermore, after generating the overall control command and before driving the actuator, a safety verification step and a closed-loop feedback step are also included: The safety verification step includes: calculating the instantaneous flow rate corresponding to the total target flow rate signal and the pressure fluctuation corresponding to the target pressure setpoint, and determining whether they are within the safe allowable range of the liquid cargo transmission pipeline system; The closed-loop feedback steps include: after driving the actuator to move, re-acquiring the hull motion response data, and updating the model parameters used to calculate the hull modal parameters or generate control commands based on the new data, for the calculation of the next control cycle.

[0017] On the other hand, the present invention provides an FLNG-LNGC joint loading and unloading operation control system based on real-time operating condition feedback, comprising: The system state space construction module collects environmental excitation parameters and ship loading state parameters from the work site to construct a spatiotemporally synchronized system state space containing wave history data, ship motion response data, and cabin fluid distribution data. The dynamic risk assessment module reconstructs the instantaneous wave energy spectrum based on the wave history data and calculates the ship's instantaneous natural frequency based on the cabin fluid distribution data; it also calculates the frequency detuning safety factor between the ship's instantaneous natural frequency and the peak frequency of the instantaneous wave energy spectrum. The loading path planning module generates an asymmetric loading path when the frequency detuning safety factor is below a preset threshold. The system comprises: an asymmetric loading command, wherein the asymmetric loading command is used to change the instantaneous natural frequency of the hull by adjusting the flow distribution of each cargo tank, thereby increasing the frequency difference between the hull and the peak frequency; an active motion suppression module, which generates an active suppression command based on the hull motion response data, wherein the active suppression command includes at least a variable stiffness pressure modulation command for adjusting the pressure in the gas phase space of the cargo tank and / or a pulse momentum damping command for superimposing a periodic pulsating component on the reference loading flow; and a command synthesis and execution module, which synthesizes the asymmetric loading command and the active suppression command to generate a general control command for driving the actuators of the cargo transfer system.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention generates asymmetric loading path planning instructions by calculating the deviation between the instantaneous natural frequency of the hull and the peak frequency of the wave energy spectrum. This method utilizes the mass distribution differences of liquid cargo in each compartment to actively adjust the hull's mass rotational inertia, thereby changing the hull's natural frequency. This enables the operating system to dynamically adapt to changes in sea conditions, always maintaining frequency domain separation between the hull's modal frequency and the wave's dominant frequency, reducing the probability of hull resonance, and extending the operational time under adverse sea conditions.

[0019] 2. This invention utilizes the compressibility of the gas phase space and the momentum flux of the liquid phase fluid to generate an active suppression command for gas-liquid coupling. By adjusting the gas phase pressure according to the ship's motion phase to change the vertical restoring force, and by superimposing anti-phase pulses in the injection flow to generate a damping torque, this method directly reuses the cargo transport system to dissipate energy and compensate for the high-frequency disturbances in the wave frequency band without introducing additional anti-roll devices, thereby reducing the amplitude of the ship's heave and roll motion.

[0020] 3. This invention constructs a spatiotemporally synchronized system state space and implements feedback-based closed-loop control. By unifying the time reference of multi-source sensor data and adaptively correcting the hydrodynamic coefficient, the problem of model parameter drift during variable mass processes is solved. At the same time, safety verification logic for pipeline flow velocity and pressure is introduced in the underlying instruction synthesis stage to ensure that the physical state of the liquid cargo transfer system is always within the safe operating range when executing high-frequency pulse control, thus ensuring the safety of operations. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a sub-flowchart of the asymmetric loading path planning of the present invention; Figure 3 This is a schematic diagram of the closed-loop control system of the present invention. Detailed Implementation

[0023] 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.

[0024] In specific implementation, the method proposed in the technical solution of this invention can be automatically executed by those skilled in the art using computer software technology. System devices for implementing the method, such as computer-readable storage media storing the corresponding computer program of the technical solution of this invention and computer equipment including the computer program running the corresponding computer program, should also be within the protection scope of this invention.

[0025] Example 1 like Figure 1-3 As shown in the figure, this embodiment provides a control method for FLNG-LNGC joint loading and unloading operations based on real-time operating condition feedback, which includes the following steps: S1. Collect environmental excitation parameters and ship loading status parameters at the work site to construct a spatiotemporally synchronized system state space containing wave history data, ship motion response data, and compartment fluid distribution status data; S2. Reconstruct the instantaneous wave energy spectrum based on the wave history data, and calculate the ship's instantaneous natural frequency based on the compartment fluid distribution status data; calculate the frequency detuning safety factor between the ship's instantaneous natural frequency and the peak frequency of the instantaneous wave energy spectrum; S3. When the frequency detuning safety factor is lower than a preset threshold, generate an asymmetric loading command. The asymmetric loading command is used to change the ship's instantaneous natural frequency by adjusting the flow distribution of each cargo tank, so as to increase the frequency difference between it and the peak frequency; S4. Generate an active suppression command based on the ship motion response data. The active suppression command includes at least a variable stiffness pressure modulation command for adjusting the pressure of the gas phase space in the cargo tank and / or a pulse momentum damping command for superimposing periodic pulsating components on the reference loading flow rate; S5. Synthesize the asymmetric loading command and the active suppression command to generate a general control command to drive the actuator of the cargo transfer system.

[0026] In step S1, a spatiotemporally synchronized system state space is constructed. Wave history data is acquired using a non-contact sea surface measurement device, the six-degree-of-freedom motion response data of the hull is collected using an inertial measurement unit, and the fluid distribution state data of the compartments is acquired through a liquid level and pressure monitoring system. The fluid distribution state data of the compartments includes at least the fluid mass and center-of-mass position of each compartment. Using linear interpolation or a zero-order hold algorithm, the environmental excitation parameters, hull motion parameters, and compartment load parameters with different sampling frequencies are unified to the same time reference axis to construct a state vector characterizing the real-time dynamic characteristics of the system.

[0027] In step S2, the instantaneous wave energy spectrum is reconstructed and the ship's modal parameters are calculated. The processing unit performs a fast Fourier transform on the wave history data to identify the peak frequencies of wave energy concentration. .

[0028] Meanwhile, given that the LNGC is a variable mass system during loading and unloading operations, a simplified rigid body dynamics model based on discrete mass points is established according to real-time compartment fluid distribution data. The specific solution process is as follows: Get the current time Hull empty ship mass distribution Its center of gravity and the location of each liquid cargo tank Real-time mass of internal fluid The longitudinal distance between its center of mass and the ship's center of gravity ; Calculate the total pitch inertia of the entire ship using the parallel axis theorem. : ; in, For the number of liquid cargo tanks, The moment of inertia of a ship in pitching motion. The additional mass inertia of the hull is taken into account for the hydrodynamic effects; Calculate the ship's pitch recovery stiffness coefficient based on the current draft and waterline area. ; Calculate the current instantaneous pitching natural frequency of the hull. : ; To quantify resonance risk, a frequency detuning safety factor is defined. The calculation logic is as follows: ; The frequency detuning safety factor is compared with the preset safety threshold. If the calculated result is lower than the threshold, it is determined that there is a resonance risk and subsequent active control steps are triggered.

[0029] In step S3, asymmetric loading path planning based on frequency detuning optimization is performed. This step mainly targets low-frequency offset and aims to adjust the ship's natural frequency by changing the mass distribution. The system establishes the following nonlinear programming mathematical model to solve for the optimal flow distribution: Define the decision variable: the distribution flow vector of each liquid cargo tank at the next moment. ; Establish the optimization objective function The aim is to maximize the deviation between the natural frequency and the wave frequency. ; in, Assuming according to flow The predicted natural frequency at the next moment after loading; Set engineering constraints: Flow conservation constraint: ( Set the flow rate for the main pipeline. For liquid cargo tanks (Distribute traffic); Valve and piping capacity constraints: ( (Maximum allowable flow rate for valves and pipelines). Strength and stability constraints: (Shear force limitation) (Stability height limit).

[0030] The objective function is solved using either Sequential Quadratic Programming (SQP) or a genetic algorithm to obtain the optimal flow allocation vector. At this point, the aforementioned strategy of "prioritizing allocation to the front, rear, or middle compartments" serves as the initial search direction or heuristic rule for the optimization algorithm, assisting the algorithm to converge quickly. The final generated asymmetric loading command contains the specific liquid inlet timing and precise flow rate values ​​for each compartment. The control sequence.

[0031] In step S4, an active suppression command for gas-liquid coupling is generated. This step mainly targets the control of high-frequency disturbances in the wave frequency band.

[0032] On one hand, a variable stiffness pressure modulation command is generated. Utilizing the compressibility of the gas in the liquid cargo tank's vapor space, the vapor space is considered as an air spring attached to the fluid surface. The control system calculates the vapor space pressure setpoint based on the following control law. : ; in, As the benchmark operating pressure, This is the pressure modulation gain coefficient. This represents the vertical displacement of the ship's hull.

[0033] The mechanism of this command is as follows: when the ship moves downwards... When the back pressure is increased, the gas back pressure setpoint is actively increased to generate additional restoring force through gas compression, thereby improving the system's equivalent stiffness; conversely, the back pressure is decreased. By dynamically adjusting the stiffness, the system's response transfer function to the high-frequency components of waves is changed, suppressing the vertical vibration amplitude.

[0034] On the other hand, pulse momentum damping commands are generated. Active control torque is produced using the momentum flux injected by the fluid. The control system, above the reference loading flow rate, superimposes a periodic pulsating component opposite to the ship's rolling motion, injecting a mass flow rate... The control law is as follows: ; In the formula, The baseline flow rate (i.e., the flow rate allocated to each compartment calculated in step S3) ), For modulation amplitude, Let be the roll phase at time t. This is the phase lead angle. This command drives the actuator to generate a damping torque that counteracts the ship's motion, thus dissipating the ship's kinetic energy.

[0035] In step S5, instruction synthesis and closed-loop execution are performed.

[0036] Instruction synthesis process: Traffic command synthesis: The system will synthesize the optimal traffic allocation vector generated in step S3. Each element in the data is used as a reference component. Substituting the pulse control law formula from step S4, the final total target flow signal for each valve is calculated. .

[0037] Pressure command issuance: The pressure command calculated in step S4 is used to... It is directly used as the setpoint (SP) for the gas phase space pressure regulation loop.

[0038] Perform the conversion process: The system pre-stores three-dimensional characteristic curves (or characteristic maps) of valve and pump sets, showing "opening degree-flow rate-differential pressure". Based on real-time monitored pipeline differential pressure and the calculated total target flow rate signal... By using reverse lookup tables or interpolation, the corresponding specific valve opening command (%) and pump speed command (RPM) are calculated. Simultaneously, based on the gas phase space pressure setpoint, the opening of the gas phase return valve is calculated using a PID controller.

[0039] Before the command is issued, the system performs a safety check to verify whether the superimposed instantaneous flow velocity and pressure fluctuations are within the allowable range of the pipeline system. After the actuator moves, the sensor network re-collects the hull response, and the system updates the estimated values ​​of the hydrodynamic coefficient matrix and damping matrix accordingly, and corrects the control parameters for the next cycle.

[0040] Example 2 This embodiment provides a FLNG-LNGC joint loading and unloading operation control system based on real-time operating condition feedback, including: The system state space construction module collects environmental excitation parameters and ship loading state parameters from the work site to construct a spatiotemporally synchronized system state space containing wave history data, ship motion response data, and cabin fluid distribution data. The dynamic risk assessment module reconstructs the instantaneous wave energy spectrum based on the wave history data and calculates the ship's instantaneous natural frequency based on the cabin fluid distribution data; it also calculates the frequency detuning safety factor between the ship's instantaneous natural frequency and the peak frequency of the instantaneous wave energy spectrum. The loading path planning module generates an asymmetric loading path when the frequency detuning safety factor is below a preset threshold. The system comprises: an asymmetric loading command, wherein the asymmetric loading command is used to change the instantaneous natural frequency of the hull by adjusting the flow distribution of each cargo tank, thereby increasing the frequency difference between the hull and the peak frequency; an active motion suppression module, which generates an active suppression command based on the hull motion response data, wherein the active suppression command includes at least a variable stiffness pressure modulation command for adjusting the pressure in the gas phase space of the cargo tank and / or a pulse momentum damping command for superimposing a periodic pulsating component on the reference loading flow; and a command synthesis and execution module, which synthesizes the asymmetric loading command and the active suppression command to generate a general control command for driving the actuators of the cargo transfer system.

[0041] It should be understood that any parts not described in detail in this specification belong to the prior art.

[0042] It should be understood that the above description of the preferred embodiments is quite detailed, but this should not be construed as limiting the scope of protection of this invention. It is neither necessary nor possible to exhaustively describe all possible implementations. Those skilled in the art, guided by this invention, can make substitutions or modifications without departing from the scope of the claims, all of which fall within the scope of protection of this invention. The scope of protection of this invention should be determined by the appended claims.

Claims

1. A control method for FLNG-LNGC joint loading and unloading operations based on real-time operating condition feedback, characterized in that, Includes the following steps: Environmental excitation parameters and ship loading status parameters are collected at the work site to construct a spatiotemporally synchronized system state space containing wave history data, ship motion response data, and compartment fluid distribution data. Based on the wave history data, the instantaneous wave energy spectrum is reconstructed, and the ship's instantaneous natural frequency is calculated based on the compartment fluid distribution data. A frequency detuning safety factor is calculated between the ship's instantaneous natural frequency and the peak frequency of the instantaneous wave energy spectrum. When the frequency detuning safety factor is lower than a preset threshold, an asymmetric loading command is generated. This asymmetric loading command is used to change the ship's instantaneous natural frequency by adjusting the flow distribution of each cargo tank, thereby increasing the frequency difference between it and the peak frequency. Based on the ship motion response data, an active suppression command is generated. This active suppression command includes at least a variable stiffness pressure modulation command for adjusting the pressure in the cargo tank's gas phase space and / or a pulse momentum damping command for superimposing periodic pulsating components onto a reference loading flow rate. The asymmetric loading command and the active suppression command are synthesized to generate a general control command that drives the actuators of the cargo transfer system.

2. The FLNG-LNGC joint loading and unloading operation control method based on real-time operating condition feedback according to claim 1, characterized in that, The construction of the spatiotemporally synchronized system state space includes: Wave history data is acquired using non-contact sea surface measurement equipment, six-degree-of-freedom motion response data of the hull is collected using an inertial measurement unit, and fluid distribution data of the compartments is acquired through a liquid level and pressure monitoring system. The fluid distribution data of the compartments includes at least the fluid mass and center of mass position of each compartment. Wave history data, six-degree-of-freedom motion response data of the hull, and fluid distribution data from different sampling frequencies are unified to the same time reference axis through a time synchronization algorithm to form a system state vector.

3. The FLNG-LNGC joint loading and unloading operation control method based on real-time operating condition feedback according to claim 1, characterized in that, The calculation of the ship's instantaneous natural frequency includes: Based on the fluid mass and center of mass position of each compartment at the current moment, combined with the empty ship mass distribution and its pitching moment of inertia, the parallel axis theorem is applied to calculate the total pitching moment of inertia of the entire ship at the current moment. Calculate the pitch recovery stiffness coefficient based on the current hull draft and waterline area; The instantaneous natural frequency of the hull is calculated based on the total pitch inertia and the pitch recovery stiffness coefficient.

4. The FLNG-LNGC joint loading and unloading operation control method based on real-time operating condition feedback according to claim 1, characterized in that, The aforementioned generation of asymmetric load instructions includes: With the optimization objective of maximizing the frequency difference between the instantaneous natural frequency and the peak frequency of the hull at the next prediction time, and with the constraints of total flow conservation, pipeline valve capacity, and hull strength and stability, a nonlinear programming model is established. Solve the nonlinear programming model to obtain the optimal flow allocation vector, and generate a control sequence that includes the liquid inlet timing and flow rate of each liquid cargo tank based on the optimal flow allocation vector.

5. The FLNG-LNGC joint loading and unloading operation control method based on real-time operating condition feedback according to claim 4, characterized in that, The process of solving the optimization objective includes: prioritizing the allocation of flow to the bow and stern compartments of the hull to reduce the instantaneous natural frequency of the hull, or prioritizing the allocation of flow to the midship compartments of the hull to increase the instantaneous natural frequency of the hull.

6. The FLNG-LNGC joint loading and unloading operation control method based on real-time operating condition feedback according to claim 1, characterized in that, The aforementioned command for generating variable stiffness pressure modulation is specifically as follows: Based on the real-time displacement and phase of the ship's vertical motion, and according to the preset pressure modulation control law, the target pressure setpoint of the liquid cargo tank's gas phase space is dynamically calculated and output. The pressure modulation control law is: in, The setpoint for the gas phase space pressure at time t. As the benchmark operating pressure, This is the pressure modulation gain coefficient. Let be the vertical displacement of the ship's hull at time t.

7. The FLNG-LNGC joint loading and unloading operation control method based on real-time operating condition feedback according to claim 1, characterized in that, The aforementioned command for generating pulse momentum damping is specifically as follows: Above the baseline flow rate of each compartment determined by the asymmetric loading command, a periodic pulsating component with a preset modulation amplitude and phase lead angle, opposite in phase to the hull roll motion, is superimposed to form a total target flow rate signal with damping effect; the periodic pulsating component is generated according to the following control law: in, Let be the mass flow rate at time t. As the baseline flow rate, For modulation amplitude, Let be the roll phase at time t. This is the phase lead angle.

8. The FLNG-LNGC joint loading and unloading operation control method based on real-time operating condition feedback according to claim 1, characterized in that, The synthesis instructions include: The reference flow rate of each compartment determined by the asymmetric loading command is superimposed with the periodic pulsation component determined by the pulse momentum damping command to synthesize the final total target flow rate signal of each liquid cargo tank. The target pressure setting value determined by the variable stiffness pressure modulation command is used as the setting value of the gas phase pressure control loop.

9. The FLNG-LNGC joint loading and unloading operation control method based on real-time operating condition feedback according to claim 8, characterized in that, After generating the overall control command and before driving the actuator, a safety verification step and a closed-loop feedback step are also included: The safety verification step includes: calculating the instantaneous flow rate corresponding to the total target flow rate signal and the pressure fluctuation corresponding to the target pressure setpoint, and determining whether they are within the safe allowable range of the liquid cargo transmission pipeline system; The closed-loop feedback steps include: after driving the actuator to move, re-acquiring the hull motion response data, and updating the model parameters used to calculate the hull modal parameters or generate control commands based on the new data, for the calculation of the next control cycle.

10. A combined FLNG-LNGC loading and unloading operation control system based on real-time operating condition feedback, characterized in that, include: The system state space construction module is used to collect environmental excitation parameters and ship loading state parameters at the operation site, and construct a spatiotemporally synchronized system state space containing wave history data, ship motion response data, and compartment fluid distribution state data. The dynamic risk assessment module is used to reconstruct the instantaneous wave energy spectrum based on the wave history data, and calculate the ship's instantaneous natural frequency based on the compartment fluid distribution state data; it also calculates the frequency detuning safety factor between the ship's instantaneous natural frequency and the peak frequency of the instantaneous wave energy spectrum. The loading path planning module is used to generate an asymmetric loading command when the frequency detuning safety factor is lower than a preset threshold. This asymmetric loading command is used to change the ship's instantaneous natural frequency by adjusting the flow distribution of each cargo tank, thereby increasing the frequency difference between the ship's instantaneous natural frequency and the peak frequency. An active motion suppression module is used to generate active suppression commands based on the hull motion response data. The active suppression commands include at least a variable stiffness pressure modulation command for adjusting the pressure in the gas phase space of the cargo tank and / or a pulse momentum damping command for superimposing periodic pulsating components on a reference loading flow rate. An instruction synthesis and execution module is used to synthesize the asymmetric loading command and the active suppression command to generate a general control command to drive the actuators of the cargo transfer system. The FLNG-LNGC joint loading and unloading operation control system based on real-time operating condition feedback is used to execute the steps in the FLNG-LNGC joint loading and unloading operation control method based on real-time operating condition feedback as described in any one of claims 1-9.

Images