A method and device for suppressing offshore wind power oscillation and a storage medium

Abstract

The application discloses a kind of offshore wind power oscillation suppression method, device and storage medium, wherein method includes: the three-phase voltage of the public coupling point of grid-connected inverter is collected;Phase compensation is obtained to three-phase voltage compensated three-phase voltage, and dq transformation is carried out to the dq axis component of compensated three-phase voltage, and the phase of grid-connected system is locked according to the dq axis component of compensated three-phase voltage;After phase locking, the dq axis component of compensated three-phase voltage is used as the input variable of virtual resistance frequency domain action formula to set virtual resistance, and virtual resistance is inserted into the current loop of grid-connected system as positive resistance, and the oscillation of grid-connected system is suppressed according to virtual resistance.The application can effectively provide full-band oscillation suppression, so as to effectively improve the suppression efficiency of grid-connected system.

Description

Technical Field

[0001] This invention relates to the field of offshore wind power technology, and in particular to a method, apparatus and storage medium for suppressing offshore wind power oscillations. Background Technology

[0002] Currently, my country's new energy power generation is mainly based on wind power and photovoltaic power generation. By the end of 2016, my country's installed capacity of wind and solar power reached 226 million kilowatts, exceeding one-quarter of the global total and accounting for approximately 14% of my country's total power capacity. However, my country's wind and solar resources are mainly concentrated in the "Three Norths" region (Northeast, North China, and Northwest my country). This inverse distribution of resources and load dictates that large-scale centralized development and long-distance transmission are among the dominant forms of large-scale development and utilization of new energy in my country. The "Three Norths" new energy bases exhibit a "double high" characteristic: a high proportion of new energy and a high proportion of power electronic equipment. This weakens the system's synchronization characteristics, and its stability characteristics undergo profound changes compared to traditional power systems, exhibiting characteristics of a weak power grid. Since 2009, domestic and international new energy power generation grid-connected systems have frequently experienced broadband oscillations ranging from subsynchronous to several hundred Hz. Several domestic new energy bases put into operation in the past two years face significant broadband oscillation risks via AC / DC transmission systems, becoming one of the important factors restricting the transmission and consumption of new energy.

[0003] Existing methods for suppressing oscillations in offshore wind power generally employ series high-pass filters to avoid affecting the inverter's base frequency operating point. However, considering that fluctuations in grid impedance can cause changes in the oscillation frequency, existing oscillation suppression methods cannot provide full-band oscillation suppression when the oscillation frequency is lower than the cutoff frequency of the high-pass filter. Summary of the Invention

[0004] This invention provides a method, apparatus, and storage medium for suppressing offshore wind power oscillations, thereby addressing the technical problem that existing offshore wind power oscillation suppression methods are limited by the cutoff frequency design of high-pass filters and cannot provide full-band oscillation suppression.

[0005] An embodiment of the present invention provides a method for suppressing offshore wind power oscillations, comprising:

[0006] Collect the three-phase voltage at the common coupling point of the grid-connected inverter;

[0007] The three-phase voltage is phase-compensated to obtain a compensated three-phase voltage. The compensated three-phase voltage is then subjected to dq transformation to obtain the dq-axis component of the compensated three-phase voltage. The grid-connected system is then phase-locked based on the dq-axis component of the compensated three-phase voltage.

[0008] After phase locking, the virtual resistor is set using the dq-axis component of the three-phase voltage as the input variable of the virtual resistor frequency domain function. The virtual resistor is then inserted as a positive resistor into the current loop of the grid-connected system, and the grid-connected system is oscillated and suppressed based on the virtual resistor.

[0009] Furthermore, before obtaining the compensated three-phase voltage through the three-phase voltage phase compensation, the process further includes:

[0010] The three-phase current at the common coupling point of the grid-connected inverter is collected, and the three-phase current is transformed by dq to obtain the dq-axis components of the three-phase current. The dq-axis of the current loop in the grid-connected system is controlled according to the dq-axis components of the three-phase current.

[0011] Furthermore, the step of performing a dq transformation on the compensated three-phase voltage to obtain the dq-axis components of the compensated three-phase voltage, and then performing phase-locking on the grid-connected system based on the dq-axis components of the compensated three-phase voltage, includes:

[0012] The q-axis component of the compensated three-phase voltage is used as the controlled variable, and the dq transformation of the compensated three-phase voltage is performed using the output angle of the phase-locked loop.

[0013] The output angle of the phase-locked loop is corrected based on the dq transformation result until the q-axis of the compensated three-phase voltage is 0;

[0014] The output angle of the phase-locked loop when the q-axis of the compensated three-phase voltage is 0 is taken as the true phase of the compensated three-phase voltage.

[0015] Furthermore, the virtual resistor is set using the dq-axis component of the compensated three-phase voltage as the input variable of the virtual resistor frequency domain function, and the virtual resistor is inserted as a positive resistor into the current loop of the grid-connected system. Oscillation suppression of the grid-connected system is performed based on the virtual resistor, including:

[0016] The frequency domain expression of the virtual resistor is set as follows:

[0017]

[0018] In the formula, G vr (s) is the frequency domain expression for the virtual resistance, where the coefficient K is the damping strength of the virtual resistance, and H HPF (s) is a high-pass filter with virtual resistance, ω L The cutoff frequency;

[0019] Oscillation suppression is achieved in the grid-connected system by modifying the coefficient K in the frequency domain expression of the virtual resistor.

[0020] One embodiment of the present invention provides an offshore wind power oscillation suppression device, comprising:

[0021] The three-phase voltage acquisition module is used to acquire the three-phase voltage at the common coupling point of the grid-connected inverter.

[0022] A phase-locked module is used to compensate the three-phase voltage phase to obtain a compensated three-phase voltage, perform dq transformation on the compensated three-phase voltage to obtain the dq-axis component of the compensated three-phase voltage, and perform phase-locking on the grid-connected system based on the dq-axis component of the compensated three-phase voltage;

[0023] The oscillation suppression module is used to set a virtual resistor after phase locking, using the dq-axis component of the three-phase voltage as the input variable of the virtual resistor frequency domain function, inserting the virtual resistor as a positive resistor into the current loop of the grid-connected system, and suppressing oscillation of the grid-connected system according to the virtual resistor.

[0024] Furthermore, the oscillation suppression device also includes a current loop dq-axis control module, used for:

[0025] The three-phase current at the common coupling point of the grid-connected inverter is collected, and the three-phase current is transformed by dq to obtain the dq-axis components of the three-phase current. The dq-axis of the current loop in the grid-connected system is controlled according to the dq-axis components of the three-phase current.

[0026] Furthermore, the phase-locked module is also used for:

[0027] The q-axis component of the compensated three-phase voltage is used as the controlled variable, and the dq transformation of the compensated three-phase voltage is performed using the output angle of the phase-locked loop.

[0028] The output angle of the phase-locked loop is corrected based on the dq transformation result until the q-axis of the compensated three-phase voltage is 0;

[0029] The output angle of the phase-locked loop when the q-axis of the compensated three-phase voltage is 0 is taken as the true phase of the compensated three-phase voltage.

[0030] Furthermore, the oscillation suppression module is also used for:

[0031] The frequency domain expression of the virtual resistor is set as follows:

[0032]

[0033] In the formula, G vr (s) is the frequency domain expression for the virtual resistance, where the coefficient K is the damping strength of the virtual resistance, and H HPF (s) is a high-pass filter with virtual resistance, ω L The cutoff frequency;

[0034] Oscillation suppression is achieved in the grid-connected system by modifying the coefficient K in the frequency domain expression of the virtual resistor.

[0035] This invention provides a computer-readable storage medium including a stored computer program, wherein the computer program, when running, controls the device containing the computer-readable storage medium to perform the offshore wind power oscillation suppression method as described above.

[0036] This invention proposes a virtual resistor to suppress oscillations in a grid-connected inverter based on phase compensation. By combining phase compensation and virtual resistor, the virtual resistor is inserted as a positive resistor into the current loop of the grid-connected system while maintaining stable oscillation suppression. By modifying the coefficient of the virtual resistor, it can effectively provide full-band damping suppression for offshore wind power oscillations, thereby effectively improving the oscillation suppression efficiency of the grid-connected system.

[0037] Furthermore, the embodiments of the present invention use a combination of phase compensation and virtual resistance for oscillation suppression. While effectively improving oscillation suppression, it can avoid the failure of the oscillation suppression method based on virtual resistance due to the difficulty in designing the cutoff frequency of the high-pass filter, thereby effectively improving the reliability of oscillation suppression. Attached Figure Description

[0038] Figure 1 This is a flowchart illustrating a method for suppressing offshore wind power oscillations provided in an embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram of the structure of an offshore wind power grid-connected inverter partially connected to a weak grid system, provided by an embodiment of the present invention;

[0040] Figure 3 This is another schematic flowchart of a method for suppressing offshore wind power oscillations provided in an embodiment of the present invention;

[0041] Figure 4 This is a simulation waveform diagram of oscillation suppression using the offshore wind power oscillation suppression method provided in an embodiment of the present invention;

[0042] Figure 5 This is a simulation waveform diagram of oscillation suppression using a virtual resistor when the cutoff frequency of the virtual resistor high-pass filter is poorly designed, provided by an embodiment of the present invention.

[0043] Figure 6 This is a simulation waveform diagram of oscillation suppression using only the phase compensation method provided in the embodiments of the present invention;

[0044] Figure 7 This is a schematic diagram of the structure of an offshore wind power oscillation suppression device provided in an embodiment of the present invention. Detailed Implementation

[0045] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0046] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "multiple" means two or more.

[0047] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0048] Please see Figure 1 An embodiment of the present invention provides a method for suppressing offshore wind power oscillations, comprising:

[0049] S1. Collect the three-phase voltage at the common coupling point of the grid-connected inverter;

[0050] This invention is applicable to scenarios where grid-connected inverters for wind power, photovoltaics, and other applications are connected to the grid on a large scale. Please refer to [link / reference]. Figure 2 This is a control equivalent model for a grid-connected system where a grid-connected inverter is connected to a weak grid, provided by an embodiment of the present invention, wherein Z g For the impedance of a weak power grid, V gabc For three-phase power supply voltage, R f L f C f These are the resistor, inductor, and capacitor of the grid-connected inverter. The three-phase voltage at the common coupling point PCC between the grid-connected inverter and the weak current grid is V. abc The three-phase line current is I abc .

[0051] S2. The three-phase voltage phase compensation is used to obtain the compensated three-phase voltage. The compensated three-phase voltage is then transformed by dq to obtain the dq-axis component of the compensated three-phase voltage. The grid-connected system is then phase-locked according to the dq-axis component of the compensated three-phase voltage.

[0052] In this embodiment of the invention, the three-phase voltage is compensated by the phase compensation stage G in the grid-connected system. lag (s) is obtained, and the compensated three-phase voltage of the common coupling point after phase compensation is obtained. The compensated three-phase voltage is used for phase locking, which can effectively ensure that the grid-connected inverter can work normally and improve the reliability of subsequent oscillation suppression.

[0053] The dq-axis components of the compensated three-phase voltage are:

[0054]

[0055] in, To compensate for the dq-axis components of the three-phase voltage, G lag (s) represents the phase compensation stage, V abc To compensate for the three-phase voltage, θ pll This is the phase angle output of the phase-locked loop.

[0056] The frequency domain expression for the phase compensation stage is:

[0057]

[0058] Where s is the Laplace operator, b is the lag angle, and T is the lag frequency range, the embodiment of the present invention can effectively compensate for the phase difference between the three-phase voltage at the common coupling point and the actual grid voltage through phase lag compensation, so that the phase-locked loop can be actually synchronized to a higher point of the SCR, thereby effectively reducing the grid intensity and improving the stability of the grid-connected system.

[0059] Optionally, embodiments of the present invention can also combine αβ transformation and dq transformation to obtain the dq-axis components of the three-phase voltage.

[0060] S3. After phase locking, the virtual resistor is set by using the dq-axis component of the three-phase voltage as the input variable of the virtual resistor frequency domain function. The virtual resistor is inserted into the current loop of the grid-connected system as a positive resistor, and the grid-connected system is oscillated and suppressed according to the virtual resistor.

[0061] In this embodiment of the invention, the insertion of the virtual resistor is equivalent to adding an action path in the current loop. The input variable of the virtual resistor is the dq-axis component of the three-phase voltage, meaning the output of the current loop is the corresponding three-phase current. In this embodiment, the virtual resistor is inserted into the grid-connected system as a positive resistor, providing corresponding damping to the grid-connected inverter, thereby effectively suppressing oscillations in the grid-connected system.

[0062] Please see Figure 3 This is another flowchart illustrating a method for suppressing offshore wind power oscillations provided in an embodiment of the present invention.

[0063] In one embodiment, before obtaining compensated three-phase voltages through three-phase voltage phase compensation, the method further includes:

[0064] The three-phase current at the common coupling point of the grid-connected inverter is collected, and the dq-axis components of the three-phase current are obtained by dq transformation. The dq-axis of the current loop in the grid-connected system is controlled based on the dq-axis components of the three-phase current.

[0065]

[0066] Among them, i dq Let I be the dq-axis component of the three-phase current. abc For three-phase current, θ pll To provide the phase angle output of the phase-locked loop, embodiments of the present invention can also combine αβ transformation and dq transformation to obtain the dq-axis components of the three-phase current.

[0067] In this embodiment of the invention, the three-phase current of the common coupling point of the grid-connected inverter is also collected, and the dq-axis control of the current loop is realized based on the dq-axis component of the three-phase current.

[0068] In this embodiment of the invention, three-phase voltage and three-phase current are input to the controller of the grid-connected inverter through voltage and current sensors.

[0069] In one embodiment, the dq-axis components of the compensated three-phase voltage are obtained by performing a dq-transformation on the compensated three-phase voltage, and the grid-connected system is phase-locked based on the dq-axis components of the compensated three-phase voltage, including:

[0070] The q-axis component of the compensated three-phase voltage is used as the controlled variable, and the dq transformation of the compensated three-phase voltage is performed using the output angle of the phase-locked loop.

[0071] The output angle of the phase-locked loop is corrected based on the dq transformation result until the q-axis of the three-phase voltage compensation is 0;

[0072] The output angle of the phase-locked loop when the q-axis of the compensated three-phase voltage is 0 is taken as the true phase of the compensated three-phase voltage.

[0073] In this embodiment of the invention, the d-axis component of the compensated three-phase voltage is: The q-axis component of the compensated three-phase voltage is The principle of phase-locked loop control in this embodiment of the invention is as follows: extracting When the combined vector of the three-phase voltages at the common coupling point is aligned with the d-axis, the output angle θ of the phase-locked loop is at this point. PLL The dq transformation performed will make

[0074] In one embodiment, a virtual resistor is set using the dq-axis component of the compensated three-phase voltage as the input variable of the virtual resistor frequency domain function. This virtual resistor is then inserted as a positive resistor into the current loop of the grid-connected system. Oscillation suppression of the grid-connected system is performed based on the virtual resistor, including:

[0075] The frequency domain expression for the virtual resistor is set as follows:

[0076]

[0077] In the formula, G vr (s) is the frequency domain expression for the virtual resistance, where the coefficient K is the damping strength of the virtual resistance, and H HPF (s) is a high-pass filter with virtual resistance, ω L The cutoff frequency;

[0078] Oscillation suppression in grid-connected systems can be achieved by modifying the coefficient K in the frequency domain expression of the virtual resistor.

[0079] In this embodiment of the invention, the dq-axis components of the three-phase voltage are fed back from the grid voltage to design a frequency domain expression for the virtual resistor, and the virtual resistor is added to the input of the current loop. This frequency domain expression is the product of a constant and a high-pass filter.

[0080] In this embodiment of the invention, the cutoff frequency in the frequency domain expression of the virtual resistor can be set to avoid the influence of the fundamental operating point. Furthermore, the damping of the virtual resistor can be corrected by modifying the value of the coefficient K as needed, thereby effectively suppressing oscillations. Optionally, the value of the coefficient K is typically between -1 and 0.

[0081] Please refer to 4-6 for simulation waveforms of oscillation suppression using different methods.

[0082] Please refer to Figure 4 The image shown is a waveform simulation diagram of the offshore wind power oscillation suppression method according to an embodiment of the present invention. Figure 4 The simulation results shown demonstrate that, under the oscillation interaction scenario between a weak power grid and a grid-connected inverter, the offshore wind power oscillation suppression method of this embodiment can achieve good oscillation suppression performance. Please refer to... Figure 5 The simulation waveform of the virtual resistor when the cutoff frequency of the high-pass filter in the virtual resistor is not designed properly is shown. Figure 5 The waveform diagram shown indicates that oscillation suppression fails in this scenario. Figure 6 The simulated waveforms show oscillation suppression using phase compensation alone. Due to fluctuations in the actual power grid impedance, Figure 6 The oscillation suppression method shown is an undercompensated approach and cannot effectively suppress oscillations.

[0083] Implementing the embodiments of the present invention has the following beneficial effects:

[0084] This invention proposes a virtual resistor to suppress oscillations in a grid-connected inverter based on phase compensation. By combining phase compensation and virtual resistor, the virtual resistor is inserted as a positive resistor into the current loop of the grid-connected system while maintaining stable oscillation suppression. By modifying the coefficient of the virtual resistor, it can effectively provide full-band damping suppression for offshore wind power oscillations, thereby effectively improving the oscillation suppression efficiency of the grid-connected system.

[0085] Furthermore, the embodiments of the present invention use a combination of phase compensation and virtual resistance for oscillation suppression. While effectively improving oscillation suppression, it can avoid the failure of the oscillation suppression method based on virtual resistance due to the difficulty in designing the cutoff frequency of the high-pass filter, thereby effectively improving the reliability of oscillation suppression.

[0086] Please see Figure 7 Based on the same inventive concept as the above embodiments, one embodiment of the present invention provides an offshore wind power oscillation suppression device, comprising:

[0087] Three-phase voltage acquisition module 10 is used to acquire the three-phase voltage at the common coupling point of the grid-connected inverter;

[0088] The phase-locked module 20 is used to obtain a compensated three-phase voltage by phase compensation of the three-phase voltage, to obtain the dq-axis component of the compensated three-phase voltage by dq transformation of the compensated three-phase voltage, and to perform phase-locking on the grid-connected system based on the dq-axis component of the compensated three-phase voltage.

[0089] The oscillation suppression module 30 is used to set a virtual resistor after phase locking, using the dq-axis component of the compensated three-phase voltage as the input variable of the virtual resistor frequency domain function, inserting the virtual resistor as a positive resistor into the current loop of the grid-connected system, and suppressing oscillation of the grid-connected system according to the virtual resistor.

[0090] In one embodiment, the oscillation suppression device further includes a current loop dq-axis control module, used for:

[0091] The three-phase current at the common coupling point of the grid-connected inverter is collected, and the dq-axis components of the three-phase current are obtained by dq transformation. The dq-axis of the current loop in the grid-connected system is controlled based on the dq-axis components of the three-phase current.

[0092] In one embodiment, the phase-locked module 20 is further configured to:

[0093] The q-axis component of the compensated three-phase voltage is used as the controlled variable, and the dq transformation of the compensated three-phase voltage is performed using the output angle of the phase-locked loop.

[0094] The output angle of the phase-locked loop is corrected based on the dq transformation result until the q-axis of the three-phase voltage compensation is 0;

[0095] The output angle of the phase-locked loop when the q-axis of the compensated three-phase voltage is 0 is taken as the true phase of the compensated three-phase voltage.

[0096] In one embodiment, the oscillation suppression module 30 is further configured to:

[0097] The frequency domain expression for the virtual resistor is set as follows:

[0098]

[0099] In the formula, G vr (s) is the frequency domain expression for the virtual resistance, where the coefficient K is the damping strength of the virtual resistance, and H HPF (s) is a high-pass filter with virtual resistance, ω L The cutoff frequency;

[0100] Oscillation suppression in grid-connected systems can be achieved by modifying the coefficient K in the frequency domain expression of the virtual resistor.

[0101] This invention provides a computer-readable storage medium including a stored computer program, wherein, when the computer program is running, it controls the device where the computer-readable storage medium is located to execute the offshore wind power oscillation suppression method described above.

[0102] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for suppressing offshore wind power oscillations, characterized in that, include: Collect the three-phase voltage at the common coupling point of the grid-connected inverter; The three-phase voltage phase is compensated to obtain the compensated three-phase voltage, and the dq-axis components of the compensated three-phase voltage are obtained by performing dq transformation on the compensated three-phase voltage: in, To compensate for the dq-axis components of the three-phase voltage, For phase compensation, It is a three-phase voltage. The phase angle output of the phase-locked loop is given; the frequency domain expression for the phase compensation stage is: in, s For the Laplace operator, b The lag angle is T, and the lag frequency range is T; the grid-connected system is phase-locked according to the dq-axis components of the compensated three-phase voltage; After phase locking, the dq-axis components of the compensated three-phase voltage are used as input variables to set the virtual resistance in the frequency domain expression of the virtual resistance. This virtual resistance is then inserted as a positive resistance into the current loop of the grid-connected system. The frequency domain expression of the virtual resistance is set as follows: In the formula, This is the frequency domain expression for the virtual resistance, where the coefficient K is the damping strength of the virtual resistance. A high-pass filter with virtual resistors. The cutoff frequency; Oscillation suppression is achieved in the grid-connected system by modifying the coefficient K in the frequency domain expression of the virtual resistor.

2. The offshore wind power oscillation suppression method as described in claim 1, characterized in that, Before obtaining the compensated three-phase voltage by performing phase compensation on the three-phase voltage, the process further includes: The three-phase current at the common coupling point of the grid-connected inverter is collected, and the three-phase current is transformed by dq to obtain the dq-axis components of the three-phase current. The dq-axis of the current loop in the grid-connected system is controlled according to the dq-axis components of the three-phase current.

3. The offshore wind power oscillation suppression method as described in claim 1, characterized in that, The step of performing a dq transformation on the compensated three-phase voltage to obtain the dq-axis components of the compensated three-phase voltage, and then performing phase-locking on the grid-connected system based on the dq-axis components of the compensated three-phase voltage, includes: The q-axis component of the compensated three-phase voltage is used as the controlled variable, and the dq transformation of the compensated three-phase voltage is performed using the output angle of the phase-locked loop. The output angle of the phase-locked loop is corrected based on the dq transformation result until the q-axis of the compensated three-phase voltage is 0; The output angle of the phase-locked loop when the q-axis of the compensated three-phase voltage is 0 is taken as the true phase of the compensated three-phase voltage.

4. A device for suppressing oscillations in offshore wind power, characterized in that, include: The three-phase voltage acquisition module is used to acquire the three-phase voltage at the common coupling point of the grid-connected inverter. The phase-locked module is used to perform phase compensation on the three-phase voltage to obtain compensated three-phase voltage, and to perform dq transformation on the compensated three-phase voltage to obtain the dq-axis components of the compensated three-phase voltage. in, To compensate for the dq-axis components of the three-phase voltage, For phase compensation, It is a three-phase voltage. The phase angle output of the phase-locked loop is given; the frequency domain expression for the phase compensation stage is: in, s For the Laplace operator, b The lag angle is T, and the lag frequency range is T; the grid-connected system is phase-locked according to the dq-axis components of the compensated three-phase voltage; The oscillation suppression module is used, after phase-locked loop (PLL), to set a virtual resistor by using the dq-axis components of the compensated three-phase voltage as input variables for the virtual resistor's frequency domain expression. This virtual resistor is then inserted as a positive resistor into the current loop of the grid-connected system. The frequency domain expression for the virtual resistor is set as follows: In the formula, This is the frequency domain expression for the virtual resistance, where the coefficient K is the damping strength of the virtual resistance. A high-pass filter with virtual resistors. The cutoff frequency; Oscillation suppression is achieved in the grid-connected system by modifying the coefficient K in the frequency domain expression of the virtual resistor.

5. The offshore wind power oscillation suppression device as described in claim 4, characterized in that, It also includes a current loop dq-axis control module, used for: The three-phase current at the common coupling point of the grid-connected inverter is collected, and the three-phase current is transformed by dq to obtain the dq-axis components of the three-phase current. The dq-axis of the current loop in the grid-connected system is controlled according to the dq-axis components of the three-phase current.

6. The offshore wind power oscillation suppression device as described in claim 4, characterized in that, The phase-locked module is also used for: The q-axis component of the compensated three-phase voltage is used as the controlled variable, and the dq transformation of the compensated three-phase voltage is performed using the output angle of the phase-locked loop. The output angle of the phase-locked loop is corrected based on the dq transformation result until the q-axis of the compensated three-phase voltage is 0; The output angle of the phase-locked loop when the q-axis of the compensated three-phase voltage is 0 is taken as the true phase of the compensated three-phase voltage.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored computer program, wherein, when the computer program is executed, it controls the device containing the computer-readable storage medium to perform the offshore wind power oscillation suppression method as described in any one of claims 1 to 3.

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