Wind-wave hybrid grid-connected optimization method based on VSG technology and feedforward control

Abstract

The present invention relates to offshore floating wind-wave complementary power generation technology, in particular to a wind-wave complementary grid-connected optimization method based on VSG technology and feedforward control. A floating wind-wave coupled cooperative power generation system is designed, and the spatiotemporal complementary characteristics of wind energy and wave energy in the marine environment are utilized to improve the utilization rate of the anchor chain system and power transmission and transformation equipment. A nonlinear mathematical model of the power generation power of the floating wind turbine and wave power generation device is constructed. A feedforward control strategy of the floating wind-wave complementary power generation system is designed, and the wind and wave conditions in the medium and far sea areas are obtained by using a laser wind measuring radar and a laser wind measuring radar. The sea conditions near the wind-wave complementary power generation system are predicted in seconds and converted into a feedforward signal for power prediction and wind turbine state adjustment. An inverter virtual synchronous control strategy is designed, and the virtual synchronous control technology is adopted. Virtual inertia and virtual damping coefficient are introduced, and the inverter is used to realize primary frequency modulation, voltage / frequency regulation, and damped oscillation suppression functions, thereby improving the stability of the grid side.

Description

Technical Field

[0001] The present invention relates to offshore floating wind-wave complementary power generation technology, and in particular to a wind-wave complementary grid-connected optimization method based on VSG technology (virtual synchronous control technology) and feedforward control. Background Art

[0002] Compared to onshore wind power, offshore wind energy resources are relatively more abundant and stable, and developing offshore wind power can reduce land use and environmental damage. As offshore resources deplete, the offshore wind power industry is targeting deeper waters with richer wind resources. Floating wind turbines offer significant advantages in water depths greater than 50 meters. Floating wind power technology secures the turbine carrier to the sea surface through a mooring system, effectively overcoming the construction challenges of fixed foundations in water depths greater than 50 meters. However, floating wind power technology faces challenges such as high construction difficulty, high technical requirements, high investment, and a long payback period. Furthermore, its power generation stability is limited by intermittent wind speeds and wave volatility. Point-absorption wave energy generators, which drive the power generation module through the relative motion of a float and seabed structures, offer high wave energy conversion efficiency. Existing technologies, such as the Norwegian Hywind Tampen project, have demonstrated the feasibility of floating wind turbine units. However, wave energy devices are often deployed using independent mooring systems, resulting in low utilization of ocean space. It is worth noting that the two systems have duplicate construction problems in infrastructure such as mooring systems and power transmission, and have not effectively utilized the motion characteristics of floating foundations to enhance wave energy capture efficiency.

[0003] More critically, the intermittent defects of a single energy system require the configuration of large-capacity energy storage devices when connected to the grid, significantly increasing the levelized cost of energy. Since the generation of wind energy is directly related to wind speed, energy output fluctuates instantaneously with changes in wind speed. For example, when the wind speed suddenly increases, the wind turbine responds immediately and increases power generation; if the wind speed drops sharply, the wind energy will decrease rapidly. The energy formation of wave energy takes time and may come from historical wind fields, so the peak of wave energy often lags behind the occurrence of strong winds. The efficiency of single energy utilization is low: traditional floating wind turbines or wave energy devices operate independently and fail to fully utilize the spatiotemporal complementarity of wind and wave energy in the marine environment, resulting in limited overall energy capture efficiency, high system cost per kilowatt-hour, and slow payback period. Therefore, structural innovation can be used to develop a wind-wave coupled power generation system that is suitable for deep-sea environments to achieve spatiotemporal complementarity of energy capture and intensive utilization of infrastructure.

[0004] Compared with traditional thermal power, single energy sources have large power fluctuations and frequency mutations: Single traditional floating wind turbines or wave energy devices are subject to factors such as changes in the natural environment, limitations of the energy conversion system, and environmental interference. The power will fluctuate significantly with the natural environment, causing a significant impact on the power grid. Wind-wave complementary power generation is prone to impacting the stability of the power grid. Due to the volatility and intermittent nature of renewable energy output (such as changes in wind speed and waves), the power output is unstable. Wind-wave complementary power generation technology does not have the mechanical inertia of traditional synchronous generators and is prone to frequency deviation or oscillation. In addition, sudden changes in renewable energy output or insufficient reactive power support can lead to local voltage fluctuations; distributed power access points may cause voltage rise due to reverse power flow.

[0005] Existing research on wind-wave-coupled floating wind-wave synergistic power generation to improve grid efficiency has largely focused on using sensors to collect real-time on-site meteorological data and then adjust the operating status of wind turbines and wave power generation devices. However, in response to the grid's scheduling needs, timely sea condition forecasts and power allocation between wind turbines and wave energy can improve grid-connected power generation efficiency to a certain extent and compensate for the intermittent nature of single-energy systems.

[0006] Chinese patent application number 202211724365.X discloses a feedforward attitude control system and method for floating wind turbines based on sea-air forecasts. The patent proposes using sea-air forecasts to formulate attitude control pre-load plans, modify attitude control plans, and formulate control exit plans. While this method can predict sea conditions over a longer time and space range, it cannot provide instantaneous sea condition predictions.

[0007] Chinese patent application number 202011153644.6 discloses a method and apparatus for reactive power compensation in a photovoltaic inverter. This method transforms the three-phase instantaneous voltage components via an abc-dq inverse transform to obtain a modulation signal. In response to the obtained modulation signal, a trigger pulse is generated to control the on / off switching of power devices in the photovoltaic inverter, performing reactive power compensation and disturbance compensation on the three-phase instantaneous current components, thereby effectively improving the photovoltaic inverter's anti-interference capability. However, this method does not consider providing inertial support and oscillation suppression when the frequency of a new energy system undergoes sudden frequency changes. Summary of the Invention

[0008] The purpose of the present invention is to overcome the shortcomings of the above-mentioned existing technologies and provide a wind-wave complementary grid-connected optimization method based on VSG technology and feedforward control. This method fully utilizes the temporal and spatial complementary characteristics of wind energy and wave energy in the marine environment, improves the utilization rate of the anchor chain system and power transmission and transformation equipment, thereby reducing the cost of electricity and improving economic benefits.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] A wind-wave hybrid grid-connected optimization method based on VSG technology and feedforward control, comprising:

[0011] (1) Installing a laser wind radar and a laser wave radar on the floating wind turbine platform of the floating wind-wave coupled coordinated power generation system to monitor the environmental information of the floating wind-wave coupled coordinated power generation system and send the information to the control system, which controls the operation of the floating wind turbine and wave energy generation device;

[0012] (2) Construct a nonlinear mathematical model of the power generation of floating wind turbines and wave energy generation devices;

[0013] The calculation formula for the predicted power generation of floating wind turbines is:

[0014] ,

[0015] in, ρ is the air density, A is the swept area, C p is the power coefficient, λ is the tip speed ratio, β is the propeller pitch, v p_wind is the predicted wind speed at the hub, η g is the generator efficiency;

[0016] The calculation formula for the predicted power generation of a point absorption wave energy power generation device is:

[0017] ,

[0018] in, B PTO is the PTO damping coefficient, v p_wave To predict wave energy velocity, η total is the total efficiency;

[0019] (3) Design a feedforward control strategy for a floating wind-wave hybrid power generation system. Use laser wind radar and laser wave radar to obtain wind and wave conditions in the middle and far sea areas, make second-level predictions of the sea conditions near the wind-wave hybrid power generation system, and convert them into feedforward signals. The wind speed feedforward signal is used to predict the power generation of the floating wind turbine and adjust the wind turbine state. By predicting the power generation, the motor torque, speed, and blade pitch of the floating wind turbine are controlled to track the maximum power generation. The wave feedforward signal is used to predict the power generation of the wave energy power generation device and adjust the PTO damping. By predicting the power generation, the motor torque, speed, and PTO damping of the wave energy power generation device are controlled to track the maximum power generation.

[0020] (4) Design a virtual synchronous control strategy for the inverter, adopt virtual synchronous control technology, introduce virtual inertia and virtual damping coefficient, and use the inverter to achieve primary frequency modulation, voltage / frequency regulation, and damped oscillation suppression functions to improve the stability of the grid side.

[0021] The feedforward control strategy of the floating wind-wave hybrid power generation system in (3) specifically includes:

[0022] (a) When the power grid is operating stably and there are no power restrictions or shutdown instructions, the floating wind turbine adjusts the motor torque, blade pitch, and impeller speed based on the second-level wind speed predicted by the laser wind radar, keeping the tip speed ratio close to the optimal value, ensuring the maximum power coefficient and output. The wave energy power generation device adjusts the PTO damping coefficient based on the second-level wave height and speed predicted by the laser wave radar to output maximum power.

[0023] (b) When the power grid issues a power limit command, the floating wind turbine reduces the generator speed and the variable pitch system increases the pitch, reducing the generated power; the wave energy generator reduces the generator speed and adjusts the damping to reduce the generated power;

[0024] (c) When the power grid fails, the floating wind turbine reduces its active power, increases its reactive power, and increases its blade pitch to prevent mechanical overload. Similarly, the wave energy generator reduces its active power, increases its reactive power, increases damping, triggers the energy dissipation device, and prevents mechanical overload.

[0025] The virtual excitation equation of the VSG in the virtual synchronous control technology (4) is as follows:

[0026] ,

[0027] Where, T e is the excitation constant, E is the virtual internal potential amplitude, E 0 is the virtual internal potential reference value of VSG in steady state, K q is the reactive-voltage regulation coefficient, Q ref 、Q are the reference reactive power and the actual output reactive power respectively.

[0028] The virtual rotor equation is used to simulate the mechanical part of the synchronous generator, and the damping coefficient is used to approximate the synchronous generator damping winding. The equation is as follows:

[0029] ,

[0030] Where, J is the virtual inertia of VSG, w is the VSG output angular velocity,w 0 is the reference angular velocity of VSG, w 0= 2πf , f=50Hz, D is the damping coefficient, P ref is the reference active power, P e is the electromagnetic active power.

[0031] The inverter monitors the deviation between the actual grid frequency and the rated frequency and its rate of change in real time. It simulates the mechanical dynamics of the synchronous generator through a virtual rotor equation and adjusts the frequency to balance the active power using virtual inertia J and damping coefficient D. The virtual inertia J provides inertial response to delay frequency mutations, while the damping coefficient D suppresses frequency oscillations and improves dynamic stability.

[0032] The inverter calculates the difference between the grid voltage and the inverter output voltage for reactive power regulation, and adjusts the virtual internal potential E by simulating the excitation system of the synchronous generator;

[0033] The active power command is generated based on the frequency error and droop characteristics; the reactive power command is generated based on the voltage difference and reactive droop characteristics;

[0034] Convert the active power command into a direct-axis (d-axis) current reference value to achieve active power control; convert the reactive power command into a quadrature-axis (q-axis) current reference value to achieve reactive power control;

[0035] Convert the current control signal of the rotating coordinate system (dq axis) back to the stationary coordinate system (α-β axis) to prepare for PWM modulation;

[0036] Generate PWM drive signals for the inverter switches based on the α-β axis voltage signals to control the output voltage waveform;

[0037] The PWM signal is distributed to the IGBT or MOSFET switching devices to achieve DC to AC conversion.

[0038] The beneficial effects of the present invention are:

[0039] 1. The floating wind-wave coupled synergistic power generation system proposed in this invention combines a floating wind turbine with a wave power generation device, fully utilizing the temporal and spatial complementarity of wind and wave energy in the marine environment, improving the utilization rate of the anchor chain system and power transmission and transformation equipment, thereby achieving the goal of reducing the cost per kilowatt-hour and improving economic benefits.

[0040] 2. Using laser wind radar and laser wind radar to obtain wind and wave conditions in mid- and far-sea areas, the system achieves second-level predictions of sea conditions near the wind-wave hybrid power generation system. These signals are converted into feedforward signals. The wind speed feedforward signals are used for wind turbine power prediction and state adjustment, while the wave feedforward signals are used for power prediction and PTO damping adjustment of the wave power generation device. The inverter then appropriately adjusts the grid power based on the power generation equipment and grid connection requirements.

[0041] 3. The inverter calculates the frequency deviation and frequency change rate according to the real-time frequency of the power grid and adjusts the virtual inertia J and damping coefficient D With the good inertia and damping characteristics of virtual synchronous control technology (VSG), when the grid voltage and frequency change, the VSG voltage and frequency under this control strategy can effectively track the grid status and achieve a smooth transition of power generation and grid connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a structural diagram of the floating wind-wave coupled synergistic power generation system of the present invention;

[0043] Figure 2 This is the control structure diagram of the floating wind-wave complementary power generation system;

[0044] Figure 3 This is the control flow chart of floating wind turbine;

[0045] Figure 4 This is a control flow chart for a wave energy power generation device;

[0046] Figure 5 This is the control flow chart of the inverter VSG.

[0047] In the picture, 1. Laser wind radar, 2. Laser wave radar. DETAILED DESCRIPTION

[0048] The present invention will be further described below with reference to the accompanying drawings and examples.

[0049] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for understanding and reading by those familiar with this technology. They are not used to limit the conditions for implementation of the present invention and therefore have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose of the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0050] like Figure 1-Figure 5 As shown in the figure, a wind-wave hybrid grid-connected optimization method based on VSG technology and feedforward control includes:

[0051] 1. Design of a floating wind-wave coupled synergistic power generation system

[0052] Analyze the wind and wave resources in the target sea area, design a floating wind turbine that matches the local resources, and then design the float diameter, PTO damping coefficient, and float draft depth based on the wave energy resources and anchoring conditions in the selected area. Figure 1 As shown, in order to monitor the sea conditions in real time and improve the efficiency of energy capture, a laser wind measurement radar 1 and a laser wave measurement radar 2 are installed on the wind turbine platform to monitor the environmental information of the floating wind-wave coupled cooperative power generation system. Figure 2 This is the control structure diagram of the floating wind-wave complementary power generation system.

[0053] 2. Establish a floating wind-wave coupled synergistic power generation system model

[0054] Construct a nonlinear mathematical model of the power generated by floating wind turbines and wave energy devices:

[0055] The predicted power calculation formula of floating wind turbine is:

[0056] ,

[0057] in, ρ is the air density, A is the swept area, C p is the power coefficient, λ is the tip speed ratio, β is the propeller pitch, v p_wind is the predicted wind speed at the hub, η g is the generator efficiency.

[0058] The calculation formula for the predicted power generation of a point absorption wave energy power generation device is:

[0059] ,

[0060] in, B PTO is the PTO damping coefficient, v p_wave To predict wave energy velocity, η total is the total efficiency (including mechanical transmission, power generation, power conversion, etc.).

[0061] The energy conversion process is described using a linear model of the power conversion and output system (PTO), and the damping coefficient is optimized through experiments. B PTO The model's accuracy was ensured through simulation and experimental verification. The structure and characteristics of floating wind-wave coupled power generation systems differ significantly from those of traditional synchronous generators. Before grid connection, the inverter controlling the renewable energy generators must exhibit inertia and damping similar to synchronous generators, enabling the system to participate in the grid's frequency and voltage regulation process and improving grid-connected system stability.

[0062] 3. Design of a feedforward control strategy for a floating wind-wave hybrid power generation system

[0063] Because floating wind and wave power generation devices are often located in deep waters, the power generation process is characterized by significant intermittency and uncertainty, seriously affecting the stable operation of the power system. Specifically, the wind-wave hybrid power generation device uses feedforward control based on wind and wave radar. By predicting the generated power, it controls the motor torque, speed, and blade pitch of the floating wind turbine to track the maximum generated power. Similarly, by predicting the generated power, it controls the motor torque, speed, and PTO damping of the wave power generation device to track the maximum generated power. Figure 2 、 Figure 3 They are the floating wind turbine control flow chart and the wave energy power generation device control flow chart respectively.

[0064] (1) When the power grid is operating stably and there are no power restrictions or shutdown instructions, the floating wind turbine adjusts the motor torque, blade pitch, and impeller speed in a timely manner based on the second-level wind speed predicted by the laser wind radar, so that the tip speed ratio is always close to the optimal value, ensuring the maximum power coefficient and outputting the maximum power. Similarly, the wave energy generator adjusts the PTO damping coefficient in a timely manner based on the second-level wave height and speed predicted by the laser wave radar to output the maximum power.

[0065] (2) When the power grid issues a power limit instruction, the floating wind turbine reduces the generator speed, and the variable pitch system increases the pitch, reducing the generated power. The wave energy power generation device reduces the generator speed and adjusts the damping to reduce the generated power.

[0066] (3) When a power grid fault occurs (voltage sag, frequency over-limit, etc.), the floating wind turbine reduces active power, increases reactive power, and increases blade pitch to prevent mechanical overload. Similarly, the wave energy generator reduces active power, increases reactive power, increases damping, triggers the energy dissipation device, and prevents mechanical overload.

[0067] 4. Design of inverter virtual synchronization control technology

[0068] In response to the large fluctuations in output voltage and frequency and difficulty in power synchronization of floating wind-wave coupled power generation systems, virtual synchronous control technology (VSG) is adopted, which introduces virtual inertia and virtual damping coefficient, and uses the inverter to achieve primary frequency modulation, voltage / frequency regulation, damped oscillation suppression and other functions to improve the stability of the grid side.

[0069] (1) In order to solve the problems of inertia loss, frequency fluctuation, voltage instability, etc. in the grid connection of renewable energy, the VSG (Virtual Synchronous Generator) control strategy is used to enable the inverter to simulate the operating characteristics of the traditional synchronous generator, thereby improving the stability, reliability and flexibility of the power system.

[0070] The virtual excitation equation of VSG is as follows:

[0071] ,

[0072] Where, T e is the excitation constant, E is the virtual internal potential amplitude, E 0 is the virtual internal potential reference value of VSG in steady state, K q is the reactive-voltage regulation coefficient, Q ref 、Q are the reference reactive power and the actual output reactive power respectively.

[0073] The virtual rotor equation is used to simulate the mechanical part of the synchronous generator, and the damping coefficient is used to approximate the synchronous generator damping winding. The equation is as follows:

[0074] ,

[0075] Where, J is the virtual inertia of VSG, w is the VSG output angular velocity, w 0 is the reference angular velocity of VSG, w 0= 2πf , f=50Hz, D is the damping coefficient, P ref is the reference active power, P e is the electromagnetic active power.

[0076] The inverter monitors the deviation (error) between the actual grid frequency and the rated frequency, as well as its rate of change, in real time. It simulates the mechanical dynamics of the synchronous generator using a virtual rotor equation and adjusts the frequency to balance active power using virtual inertia J and damping coefficient D. Virtual inertia J provides inertial response, slowing sudden frequency changes; damping coefficient D suppresses frequency oscillations and improves dynamic stability.

[0077] The inverter calculates the difference between the grid voltage and the inverter output voltage for reactive power regulation. This virtual internal potential (E) is adjusted by simulating the excitation system of a synchronous generator. The active power command is generated based on the frequency error and droop characteristics; the reactive power command is generated based on the voltage difference and reactive droop characteristics. The active power command is converted into a direct-axis (d-axis) current reference value to achieve active power control; the reactive power command is converted into a quadrature-axis (q-axis) current reference value to achieve reactive power control. The current control signal from the rotating coordinate system (dq axes) is converted back to the stationary coordinate system (α-β axes) to prepare for PWM modulation. The α-β axis voltage signals are used to generate PWM drive signals for the inverter switches, controlling the output voltage waveform. The PWM signals are distributed to switching devices such as IGBTs or MOSFETs to achieve DC-to-AC conversion.

[0078] Its core is to give the inverter "grid-friendly" characteristics similar to traditional power supplies through a virtual synchronous generator model. The virtual moment of inertia and virtual damping parameters enable the system to have inertial support and anti-interference capabilities similar to those of a synchronous generator, which can improve the dynamic characteristics of the system.

[0079] The sensor transmits the radar feedforward signal to the wind turbine system. The control system mainly consists of power prediction and pitch control systems. The power prediction system obtains the predicted power by analyzing the feedforward signal. According to the predicted power, the pitch control system changes the blade angle to achieve power regulation. When the grid demand changes (such as excessive frequency or insufficient transmission capacity), the inverter needs to reduce or limit the output power. Its control strategy is divided into two modes: active power limiting and passive power limiting. When the grid dispatch instruction requires load reduction, the active mode is activated to synchronously reduce the generator speed or trigger the pitch control system to increase the blade angle. β , reduce mechanical power input; when the power grid fails (such as voltage sag, frequency limit exceeded), reduce I d To a safe value, increase I q To increase the voltage, the pitch system is then triggered to retract the propellers to prevent mechanical overload.

[0080] Similarly, the control system for wave power generation mainly consists of power prediction and PTO damping adjustment system. The power prediction system obtains predicted power by analyzing the feedforward signal. According to the predicted power, the PTO damping adjustment system changes the damping of the floating power generation device to achieve power regulation. When the grid dispatch instruction requires load reduction, the active mode is activated to synchronously reduce the generator speed or adjust the damping to reduce the mechanical power input; when the grid fails (such as voltage sag, frequency limit exceeded), the I d To a safe value, increase I q By raising the voltage, the damping adjustment system is triggered, the damping is increased, the energy is quickly absorbed and the energy dissipation mechanism is triggered to prevent mechanical overload.

[0081] Because traditional power grids rely on the physical inertia (rotor kinetic energy) and damping characteristics of synchronous generators, they can spontaneously suppress frequency fluctuations and maintain transient stability. However, when new energy (wind power, photovoltaic) is connected to the grid through inverters, "current source" control (such as PQ control) is usually used, which cannot provide inertia and damping, resulting in a decrease in the power grid's anti-disturbance ability. In order to improve the anti-disturbance ability of inverters when connected to the grid, virtual synchronous generator (VSG) technology is used to introduce virtual rotation inertia. J , by adjusting the active power response frequency change rate ( df / dt ), delaying frequency fluctuations; introducing virtual damping to suppress frequency oscillations through damping terms and improve dynamic stability, Figure 4 This is the complete flow chart of inverter VSG control.

[0082] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A wind-wave hybrid grid-connected optimization method based on VSG technology and feedforward control, characterized by: include: (1) Installing a laser wind radar and a laser wave radar on the floating wind turbine platform of the floating wind-wave coupled coordinated power generation system to monitor the environmental information of the floating wind-wave coupled coordinated power generation system and send the information to the control system, which controls the operation of the floating wind turbine and wave energy generation device; (2) Construct a nonlinear mathematical model of the power generation of floating wind turbines and wave energy generation devices; The calculation formula for the predicted power generation of floating wind turbines is: ， in, ρ is the air density, A is the swept area, C p is the power coefficient, λ is the tip speed ratio, β is the propeller pitch, v p_wind is the predicted wind speed at the hub, η g is the generator efficiency; The calculation formula for the predicted power generation of a point absorption wave energy power generation device is: , in, B PTO is the PTO damping coefficient, v p_wave To predict wave energy velocity, η total is the total efficiency; (3) Design a feedforward control strategy for a floating wind-wave hybrid power generation system. Use laser wind radar and laser wave radar to obtain wind and wave conditions in the middle and far sea areas, make second-level predictions of the sea conditions near the wind-wave hybrid power generation system, and convert them into feedforward signals. The wind speed feedforward signal is used to predict the power generation of the floating wind turbine and adjust the wind turbine state. By predicting the power generation, the motor torque, speed, and blade pitch of the floating wind turbine are controlled to track the maximum power generation. The wave feedforward signal is used to predict the power generation of the wave energy power generation device and adjust the PTO damping. By predicting the power generation, the motor torque, speed, and PTO damping of the wave energy power generation device are controlled to track the maximum power generation. (4) Design a virtual synchronous control strategy for the inverter, adopt virtual synchronous control technology, introduce virtual inertia and virtual damping coefficient, and use the inverter to achieve primary frequency modulation, voltage / frequency regulation, and damped oscillation suppression functions to improve the stability of the grid side.

2. The wind-wave hybrid grid-connected optimization method based on VSG technology and feedforward control according to claim 1 is characterized in that: The feedforward control strategy of the floating wind-wave hybrid power generation system in (3) specifically includes: (a) When the power grid is operating stably and there are no power restrictions or shutdown instructions, the floating wind turbine adjusts the motor torque, blade pitch, and impeller speed based on the second-level wind speed predicted by the laser wind radar, keeping the tip speed ratio close to the optimal value, ensuring the maximum power coefficient and output. The wave energy power generation device adjusts the PTO damping coefficient based on the second-level wave height and speed predicted by the laser wave radar to output maximum power. (b) When the power grid issues a power limit command, the floating wind turbine reduces the generator speed and the variable pitch system increases the pitch, reducing the generated power; the wave energy generator reduces the generator speed and adjusts the damping to reduce the generated power; (c) When the power grid fails, the floating wind turbine reduces its active power, increases its reactive power, and increases its blade pitch to prevent mechanical overload. Similarly, the wave energy generator reduces its active power, increases its reactive power, increases damping, triggers the energy dissipation device, and prevents mechanical overload.

3. The wind-wave hybrid grid-connected optimization method based on VSG technology and feedforward control according to claim 1 is characterized in that: The virtual excitation equation of the VSG in the virtual synchronous control technology (4) is as follows: , Where, T e is the excitation constant, E is the virtual internal potential amplitude, E 0 is the virtual internal potential reference value of VSG in steady state, K q is the reactive-voltage regulation coefficient, Q ref 、Q are the reference reactive power and the actual output reactive power respectively; The virtual rotor equation is used to simulate the mechanical part of the synchronous generator, and the damping coefficient is used to approximate the synchronous generator damping winding. The equation is as follows: , Where, J is the virtual inertia of VSG, w is the VSG output angular velocity, w 0 is the reference angular velocity of VSG, w 0= 2πf , f=50Hz, D is the damping coefficient, P ref is the reference active power, P e is the electromagnetic active power.

4. The wind-wave hybrid grid-connected optimization method based on VSG technology and feedforward control as claimed in claim 3 is characterized in that: The inverter monitors the deviation between the actual grid frequency and the rated frequency and its rate of change in real time, simulates the mechanical dynamics of the synchronous generator through the virtual rotor equation, adjusts the frequency through the virtual inertia J and the damping coefficient D, and balances the active power. The virtual inertia J provides inertial response and delays frequency mutations; the damping coefficient D suppresses frequency oscillations and improves dynamic stability.

5. The wind-wave hybrid grid-connected optimization method based on VSG technology and feedforward control as claimed in claim 3 is characterized in that the inverter The difference between the grid voltage and the inverter output voltage is calculated for reactive power regulation, and the virtual internal potential E is adjusted by simulating the excitation system of the synchronous generator.

6. The wind-wave hybrid grid-connected optimization method based on VSG technology and feedforward control as claimed in claim 5 is characterized in that the active The power command is generated based on the frequency error and droop characteristics; the reactive power command is generated based on the voltage difference and reactive droop characteristics.

7. The wind-wave hybrid grid-connected optimization method based on VSG technology and feedforward control as claimed in claim 6 is characterized in that: The active power command is converted into a direct-axis current reference value to achieve active power control; the reactive power command is converted into a quadrature-axis current reference value to achieve reactive power control.

8. The wind-wave hybrid grid-connected optimization method based on VSG technology and feedforward control as claimed in claim 7 is characterized in that: The current control signal of the rotating coordinate system, i.e., the dq axis, is converted back to the stationary coordinate system, i.e., the α-β axis, in preparation for PWM modulation. The PWM drive signal of the inverter switch tube is generated according to the α-β axis voltage signal to control the output voltage waveform. The PWM signal is distributed to the IGBT or MOSFET switching device to realize DC to AC conversion.

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