Method and device for establishing frequency response model of offshore wind power flexible direct current grid-connected system

Abstract

The invention discloses a method and device for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system, and belongs to the field of power system safety and stability control. According to the method, active frequency support of offshore wind power is added to a frequency response model of a traditional system, meanwhile, loss changes generated in the flexible and direct active power transmission process are calculated, and a power system frequency response model containing offshore wind power flexible and direct grid connection is obtained; the method can accurately reflect the frequency response characteristics of wind power after system disturbance under the condition of flexible direct current grid connection, and provides important reference for frequency control and stable operation of a power system.

Description

Technical Field

[0001] The present invention relates to the technical field of safe and stable control of electric power systems, and in particular to a method and device for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system. Background Art

[0002] With the rapid development of new energy power generation technology, large-scale offshore wind turbines often use flexible direct current transmission (voltage source converter based high voltage DC, VSC-HVDC, referred to as flexible direct current) to access the onshore AC system. However, due to the application of flexible direct current transmission system, the onshore AC system and the offshore wind farm are decoupled, so that the change of the frequency of the onshore AC system does not affect the frequency of the offshore wind farm. Because the proportion of offshore wind power with a small inertia time constant in the power system increases, the total inertia of the AC system decreases, thereby weakening the inertia level and primary frequency regulation capability of the power grid. Because of the separation of the onshore AC system and the offshore wind farm, the offshore wind turbines cannot respond quickly to the frequency changes of the onshore AC system, which makes the frequency support of the offshore wind power flexible direct current grid-connected system face challenges. Therefore, for the wind power flexible direct current grid-connected system, offshore wind power needs to provide active frequency support to cope with various complex changes in the power system. At the same time, it is necessary to establish a suitable frequency response model to accurately simulate the frequency response characteristics of the offshore wind power flexible direct current grid-connected system, and at the same time reflect the impact of the active frequency support strategy on the system frequency regulation.

[0003] The single-machine equivalent model structure is one of the most widely used frequency response models, which mainly includes the average system frequency model and the system frequency response (SFR) model. The SFR model retains the rotor motion equation of the synchronous generator on the basis of the average system frequency model, and adopts a simplified reheat turbine-speed governor link to improve the practicality of the model.

[0004] Based on the classic system frequency response model, existing literature mainly focuses on the frequency response model of power systems with active frequency support wind turbines. When offshore wind power is connected to the grid via flexible direct current, in addition to considering the active frequency support of the wind turbine, it is also necessary to study the additional active power loss caused by the flexible direct current power transmission. The active power loss first considers the loss generated when the DC cable transmits power. In addition to the active power loss of the flexible direct current cable, the loss of the voltage source converter (VSC) in the flexible direct current also needs to be considered.

[0005] In general, in the existing research work on frequency response models of power systems containing active frequency support wind turbines, wind turbines are directly connected to the grid via AC lines, and there is a lack of research on the situation of wind power being connected to the grid via flexible direct current lines. Summary of the invention

[0006] The present invention provides a method and device for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system, which can accurately reflect the frequency response characteristics of offshore wind power after system disturbance under the condition of flexible direct current grid-connected system, and provide an important reference for frequency control and stable operation of the power system.

[0007] A first aspect of the present invention provides a method for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system, comprising the following steps:

[0008] Taking the reheat steam turbine generator as the object, the frequency response model of the traditional power system is established;

[0009] Establish a comprehensive inertial control model combining inertial control and droop control for offshore wind turbines;

[0010] Combined with the comprehensive inertial control model of offshore wind turbines, the change in active power loss of flexible direct current is calculated;

[0011] By combining the active frequency support of offshore wind turbines, the change in active power loss of flexible direct current (DC) and the frequency response model of traditional power systems, a frequency response model containing active frequency support for offshore wind power established in the offshore wind power flexible direct current (DC) grid-connected system is obtained.

[0012] Optionally, in one embodiment of the present invention, taking the reheat steam turbine generator as the object, establishing the frequency response model of the traditional power system specifically includes:

[0013] Taking the reheat steam turbine generator as the object, the governor-prime mover mathematical model is established and simplified. The simplified governor-prime mover model is combined with the rotor motion equation to obtain the frequency response model of the traditional power system:

[0014]

[0015] In the formula, H s and D are the inertia time constant and damping coefficient of the synchronous generator, respectively, K m is the coefficient related to the synchronous generator power factor and reserve capacity, F H is the work ratio of the high-pressure cylinder in the reheat turbine generator, T R is the reheat time constant of the reheat turbine generator, R is the speed regulator adjustment factor, Δf is the frequency deviation, ΔP d is the active disturbance, ΔP mis the equivalent mechanical power increment caused by frequency change, G s (s) is the frequency response model of the traditional power system.

[0016] Optionally, in one embodiment of the present invention, the step of establishing a comprehensive inertial control model combining inertial control and droop control of an offshore wind turbine generator system specifically includes:

[0017] Step 2-1, adding droop control to the offshore wind turbine;

[0018] Among them, the droop control uses the frequency deviation to simulate the governor response of the synchronous generator, and the formula is:

[0019] ΔP dr =-K dr Δf

[0020] Where ΔP dr Frequency support power provided by droop control for offshore wind turbines, K dr is the droop control coefficient, Δf is the frequency deviation;

[0021] Step 2-2, adding inertial control to the offshore wind turbine;

[0022] The purpose of inertial control is to simulate the inertial response process of conventional synchronous generators and use the grid frequency change rate as the input signal of additional power control to adjust the power output of offshore wind turbines. The formula is:

[0023]

[0024] Where ΔP in Frequency support power provided by inertial control for offshore wind turbines, K in is the inertia control coefficient;

[0025] Step 2-3, adding comprehensive inertia control to the additional control of the offshore wind turbine generator set, the comprehensive inertia control including inertia control and droop control of the offshore wind turbine generator set;

[0026] Among them, the comprehensive inertial control model of offshore wind turbines is specifically expressed as:

[0027]

[0028] Where ΔP WT The total power provided by the offshore wind turbine through inertia and droop control, f ref is the reference value of frequency, and f is the actual measured frequency.

[0029] Optionally, in one embodiment of the present invention, the calculating of the change in the active power loss of the flexible direct current in combination with the comprehensive inertia control model of the offshore wind turbine generator set specifically includes:

[0030] Step 3-1, calculate the active power loss of the flexible DC cable:

[0031]

[0032] Where P CR is the active power loss of the flexible DC cable, I VSC is the DC current of the flexible DC, R is the equivalent resistance of the flexible DC transmission line, U dc is the soft DC voltage, P WT The amount of active power delivered to the flexible DC power supply to the wind turbine;

[0033] Step 3-2, calculate the active power loss of the flexible DC converter:

[0034]

[0035] Where P closs It is the sum of the active power loss of VSC caused by the conduction loss and switching loss of power electronic devices. The coefficient a simulates the loss that is linearly related to the square of the active power delivered by the wind turbine to the flexible DC, the coefficient b simulates the loss that is linearly related to the active power delivered by the wind turbine to the flexible DC, and the coefficient c simulates the fixed loss.

[0036] Step 3-3, calculate the change in the active power loss of the flexible DC cable according to the active power loss of the flexible DC converter and the integrated inertia control model of the offshore wind turbine:

[0037]

[0038] In the formula, the change in active power loss of flexible DC is ΔP loss Including the active power loss change of the flexible DC converter ΔP closs And the active power loss change of the flexible DC cable ΔP CR , P WT0 P is the active power delivered to the flexible direct current by the offshore wind turbine when the offshore wind power flexible direct current grid-connected system is operating normally. WT1 is the active power delivered to the flexible direct current by the offshore wind power flexible direct current grid-connected system after the disturbance occurs, ΔP WT The total power provided by the offshore wind turbine through inertia and droop control, P VSC1loss0 and P VSC1loss1 is the loss of the flexible DC receiving end converter before and after the disturbance, P VSC2loss0 and P VSC2loss1 is the loss of the flexible DC sending end converter before and after the disturbance, PCR0 and P CR1 is the loss of the flexible DC cable before and after the disturbance, I VSC1 and I VSC0 They are the magnitude of the DC current of the flexible DC after the disturbance and the magnitude of the DC current of the flexible DC before the disturbance, and the coefficient a 1 and coefficient a 2 is the secondary loss coefficient of the flexible DC receiving and sending converters, and the coefficient b 1 and coefficient b 2 is the primary loss coefficient of the flexible DC receiving and sending converters, and the coefficient c 1 and coefficient c 2 is the constant loss coefficient of the flexible DC receiving and sending converters.

[0039] Optionally, in one embodiment of the present invention, the active frequency support of the offshore wind turbine, the change in active power loss of the flexible direct current and the frequency response model of the traditional power system are combined to obtain a frequency response model containing active frequency support of offshore wind power established in the offshore wind power flexible direct current grid-connected system, which specifically includes:

[0040] Step 4-1, integrating the frequency response model of offshore wind power active frequency support and traditional power system:

[0041] Through the system frequency deviation and the system frequency change rate, the total power ΔP provided by the offshore wind turbine through inertia control and droop control is obtained. WT , and ΔP WT Adding it to the frequency response model of the traditional power system, we get the frequency response model including active frequency support of wind turbines:

[0042]

[0043] Step 4-2, the frequency response model including active frequency support for offshore wind power consists of the frequency response model of the traditional power system and the frequency response model including active frequency support for wind turbines. The frequency response model of the traditional power system adopts a simplified low-order frequency response model, and the active frequency support control of wind turbines adopts a comprehensive inertia control combining inertia control and droop control. At the same time, the loss changes in the process of flexible direct current transmission of active power are considered, and finally the frequency response model including active frequency support for offshore wind power is established:

[0044]

[0045] Where ΔP d It is active disturbance.

[0046] A second aspect of the present invention provides a device for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system, comprising:

[0047] The first building module is used to build a frequency response model of a traditional power system with a reheat steam turbine generator as an object;

[0048] The second building module is used to build a comprehensive inertial control model combining inertial control and droop control of offshore wind turbines;

[0049] A calculation module is used to calculate the change in active power loss of the flexible direct current in combination with a comprehensive inertial control model of the offshore wind turbine;

[0050] The third module is used to combine the active frequency support of offshore wind turbines, the change in active power loss of flexible direct current and the frequency response model of traditional power systems to obtain a frequency response model containing active frequency support for offshore wind power established in the offshore wind power flexible direct current grid-connected system.

[0051] Optionally, in one embodiment of the present invention, the first establishing module is specifically used to:

[0052] Taking the reheat steam turbine generator as the object, the governor-prime mover mathematical model is established and simplified. The simplified governor-prime mover model is combined with the rotor motion equation to obtain the frequency response model of the traditional power system:

[0053]

[0054] In the formula, H s and D are the inertia time constant and damping coefficient of the synchronous generator, respectively, K m is the coefficient related to the synchronous generator power factor and reserve capacity, F H is the work ratio of the high-pressure cylinder in the reheat turbine generator, T R is the reheat time constant of the reheat turbine generator, R is the speed regulator adjustment factor, Δf is the frequency deviation, ΔP d is the active disturbance, ΔP m is the equivalent mechanical power increment caused by frequency change, G s (s) is the frequency response model of the traditional power system.

[0055] Optionally, in one embodiment of the present invention, the second establishing module is specifically used to:

[0056] Droop control is added to the offshore wind turbine; the droop control uses the frequency deviation to simulate the governor response of the synchronous generator, and the formula is:

[0057] ΔP dr =-K dr Δf

[0058] Where ΔP drFrequency support power provided by droop control for offshore wind turbines, K dr is the droop control coefficient, Δf is the frequency deviation;

[0059] Inertial control is added to offshore wind turbines; the purpose of inertial control is to simulate the inertial response process of conventional synchronous generators and use the grid frequency change rate as the input signal of additional power control to adjust the power output of offshore wind turbines. The formula is:

[0060]

[0061] In the formula, ΔP in Frequency support power provided by inertial control for offshore wind turbines, K in is the inertia control coefficient;

[0062] In the additional control of offshore wind turbines, integrated inertia control is added. The integrated inertia control includes inertia control and droop control of offshore wind turbines. The integrated inertia control model of offshore wind turbines is specifically expressed as follows:

[0063]

[0064] In the formula, ΔP WT The total power provided by the offshore wind turbine through inertia and droop control, f ref is the reference value of frequency, and f is the actual measured frequency.

[0065] Optionally, in one embodiment of the present invention, the calculation module is specifically used for:

[0066] Calculate the active power loss of flexible DC cable:

[0067]

[0068] Where P CR is the active power loss of the flexible DC cable, I VSC is the DC current of the flexible DC, R is the equivalent resistance of the flexible DC transmission line, U dc is the soft DC voltage, P WT The amount of active power delivered to the flexible DC power supply to the wind turbine;

[0069] Calculate the active power loss of the flexible DC converter:

[0070]

[0071] Where P clossIt is the sum of the active power loss of VSC caused by the conduction loss and switching loss of power electronic devices. The coefficient a simulates the loss that is linearly related to the square of the active power delivered by the wind turbine to the flexible DC, the coefficient b simulates the loss that is linearly related to the active power delivered by the wind turbine to the flexible DC, and the coefficient c simulates the fixed loss.

[0072] According to the active power loss of the flexible DC cable and the active power loss of the flexible DC converter, combined with the comprehensive inertia control model of the offshore wind turbine, the change in the active power loss of the flexible DC is calculated:

[0073]

[0074] In the formula, the change of active power loss of flexible DC is ΔP loss Including the active power loss change of the flexible DC converter ΔP closs And the active power loss change of the flexible DC cable ΔP CR , P WT0 P is the active power delivered to the flexible direct current by the offshore wind turbine when the offshore wind power flexible direct current grid-connected system is operating normally. WT1 is the active power delivered to the flexible direct current by the offshore wind power flexible direct current grid-connected system after the disturbance occurs, ΔP WT The total power provided by the offshore wind turbine through inertia and droop control, P VSC1loss0 and P VSC1loss1 is the loss of the flexible DC receiving end converter before and after the disturbance, P VSC2loss0 and P VSC2loss1 is the loss of the flexible DC sending end converter before and after the disturbance, P CR0 and P CR1 is the loss of the flexible DC cable before and after the disturbance, I VSC1 and I VSC0 They are the magnitude of the DC current of the flexible DC after the disturbance and the magnitude of the DC current of the flexible DC before the disturbance, respectively. The coefficient a 1 and coefficient a 2 is the secondary loss coefficient of the flexible DC receiving and sending converters, and the coefficient b 1 and coefficient b 2 is the primary loss coefficient of the flexible DC receiving and sending converters, and the coefficient c 1 and coefficient c 2 is the constant loss coefficient of the flexible DC receiving and sending converters.

[0075] Optionally, in one embodiment of the present invention, the third establishing module is specifically used to:

[0076] Frequency response model of integrated offshore wind power active frequency support and traditional power system:

[0077] Through the system frequency deviation and the system frequency change rate, the total power ΔP provided by the offshore wind turbine through inertia control and droop control is obtained. WT , and ΔP WT Adding it to the frequency response model of the traditional power system, we get the frequency response model including active frequency support of wind turbines:

[0078]

[0079] The frequency response model including active frequency support for offshore wind power consists of the frequency response model of the traditional power system and the frequency response model including active frequency support for wind turbines. The frequency response model of the traditional power system adopts a simplified low-order frequency response model. The active frequency support control of wind turbines adopts a comprehensive inertia control combining inertia control and droop control, while considering the loss changes in the process of flexible direct current transmission of active power. The final frequency response model including active frequency support for offshore wind power is:

[0080]

[0081] Where ΔP d It is active disturbance.

[0082] A third aspect of the present invention provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to execute the method for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system as described in the above embodiment.

[0083] A fourth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, the program being executed by a processor to execute the method for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system as described in the above embodiment.

[0084] The method and device for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system according to an embodiment of the present invention add the active frequency support of offshore wind power to the frequency response model of a traditional system, and simultaneously calculate the changes in losses generated in the process of flexible direct current transmitting active power, thereby obtaining a frequency response model of a power system including offshore wind power flexible direct current grid-connected. The model can accurately reflect the frequency response characteristics of wind power after system disturbance under the condition of flexible direct current grid-connected, and can simulate the frequency response characteristics of offshore wind power after system disturbance under the condition of flexible direct current grid-connected, and at the same time reflect the influence of active frequency control strategy on system frequency modulation, thereby providing an important reference for frequency control and stable operation of power systems.

[0085] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0087] Figure 1 A flowchart of a method for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system provided according to an embodiment of the present invention;

[0088] Figure 2 A frequency response model of a conventional power system according to an embodiment of the present invention;

[0089] Figure 3 A schematic diagram of comprehensive inertia control of a wind turbine generator system according to an embodiment of the present invention;

[0090] Figure 4 A schematic diagram of calculating the change in active power loss of a flexible direct current according to an embodiment of the present invention;

[0091] Figure 5 The frequency response model including active frequency support of the wind turbine according to an embodiment of the present invention;

[0092] Figure 6 A frequency response model of an offshore wind power flexible direct current grid-connected system including offshore wind power active frequency support according to an embodiment of the present invention;

[0093] Figure 7 A power system topology diagram of an offshore wind power flexible direct current grid-connected system according to an embodiment of the present invention;

[0094] Figure 8 A comparison diagram of the frequency response curves of the detailed model and the SFR model system when the active frequency support of offshore wind power is not included in the embodiment of the present invention;

[0095] Fig. 9 A comparison diagram of frequency response curves of a detailed model and an SFR model system when active frequency support of offshore wind power is included in an embodiment of the present invention;

[0096] Fig.10 A diagram showing the change in loss during the flexible direct current energy transmission process according to an embodiment of the present invention;

[0097] Fig.11 A comparison diagram of frequency response curves of loss changes in flexible direct current transmission according to an embodiment of the present invention;

[0098] Fig.12 A structural block diagram of a device for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system provided according to an embodiment of the present invention;

[0099] Fig.13 A schematic diagram of the structure of an electronic device provided by an embodiment of the invention. DETAILED DESCRIPTION

[0100] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0101] Figure 1 The present invention is a flowchart of a method for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system according to an embodiment of the present invention.

[0102] like Figure 1 As shown, the method for establishing the frequency response model of the offshore wind power flexible direct current grid-connected system includes the following steps:

[0103] Step 1: Taking the reheat steam turbine generator as the object, a frequency response model of the traditional power system is established.

[0104] Optionally, in one embodiment of the present invention, step 1 specifically includes:

[0105] The frequency response model of the traditional power system takes the reheat steam turbine generator as the object, establishes its governor-prime mover mathematical model, ignores the links with small time constants and limit links, and combines the simplified governor-prime mover model with the rotor motion equation to obtain the following: Figure 2 SFR model shown:

[0106]

[0107] In the formula, H s and D are the inertia time constant and damping coefficient of the synchronous generator, respectively, K m is the coefficient related to the synchronous generator power factor and reserve capacity, F H is the work ratio of the high-pressure cylinder in the reheat turbine generator, T R is the reheat time constant of the reheat turbine generator, R is the speed regulator adjustment factor, Δf is the frequency deviation, ΔP d is the active disturbance, ΔP m is the equivalent mechanical power increment caused by frequency change, G s (s) is the frequency response model of the traditional power system.

[0108] Step 2: Establish a comprehensive inertial control model that combines inertial control and droop control for offshore wind turbines.

[0109] Optionally, in one embodiment of the present invention, step 2 specifically includes:

[0110] Step 2-1, adding droop control to the offshore wind turbine;

[0111] Among them, the droop control uses the frequency deviation to simulate the governor response of the synchronous generator, and the formula is:

[0112] ΔP dr =-K dr Δf

[0113] Where ΔP dr Frequency support power provided by droop control for offshore wind turbines, K dr is the droop control coefficient, Δf is the frequency deviation;

[0114] Step 2-2, adding inertial control to the offshore wind turbine;

[0115] The purpose of inertial control is to simulate the inertial response process of conventional synchronous generators and use the grid frequency change rate as the input signal of additional power control to adjust the power output of offshore wind turbines. The formula is:

[0116]

[0117] Where ΔP in Frequency support power provided by inertial control for offshore wind turbines, K in is the inertia control coefficient;

[0118] Step 2-3, adding comprehensive inertia control to the additional control of the offshore wind turbine generator set, the comprehensive inertia control including inertia control and droop control of the offshore wind turbine generator set;

[0119] Among them, the comprehensive inertial control model of offshore wind turbines is specifically expressed as:

[0120]

[0121] Where ΔP WT The total power provided by the offshore wind turbine through inertia and droop control, f ref is the reference value of frequency, and f is the actual measured frequency.

[0122] according to Figure 3 As shown, offshore wind power can provide frequency support for the power grid by responding to the frequency deviation and frequency change rate of the offshore AC system when the system is disturbed, thereby changing the wind turbine output.

[0123] Step 3, calculate the change in the active power loss of the flexible direct current in combination with the comprehensive inertia control model of the offshore wind turbine.

[0124] Optionally, in one embodiment of the present invention, step 3 specifically includes:

[0125] Step 3-1, the active power loss of offshore wind power caused by flexible direct current transmission mainly consists of two parts: the active power loss of the flexible direct current cable and the active power loss of the flexible direct current converter. The active power loss of the flexible direct current cable can be regarded as the active power loss caused by the equivalent resistance of the line. The active power loss of the flexible direct current cable is calculated as follows:

[0126]

[0127] Where P CR is the active power loss of the flexible DC cable, I VSC is the DC current of the flexible DC, R is the equivalent resistance of the flexible DC transmission line, U dc is the soft DC voltage, P WT The amount of active power delivered to the flexible DC power supply to the wind turbine;

[0128] Step 3-2: The active power loss of the flexible DC converter is obtained by using a quadratic function related to the DC current flowing through the VSC to calculate the active power loss of the flexible DC converter:

[0129]

[0130] Where P closs It is the sum of the active power loss of VSC caused by the conduction loss and switching loss of power electronic devices. The coefficient a simulates the loss that is linearly related to the square of the active power delivered by the wind turbine to the flexible DC, the coefficient b simulates the loss that is linearly related to the active power delivered by the wind turbine to the flexible DC, and the coefficient c simulates the fixed loss.

[0131] When the flexible DC grid-connected system is operating normally, the flexible DC voltage is approximately unchanged, so the active power delivered by the wind turbine to the flexible DC is proportional to the flexible DC current. Therefore, when transmitting power through the flexible DC, the converter loss model used in this paper is

[0132]

[0133] Step 3-3, when a load disturbance occurs, the system frequency changes, and the power of offshore wind power transmitted through flexible direct current changes due to comprehensive inertia control. In this process, the loss generated during flexible direct current transmission will also change. Figure 4 As shown, calculate the change in flexible direct current active power loss:

[0134]

[0135] In the formula, the change of active power loss of flexible DC is ΔP loss Including the active power loss change of the flexible DC converter ΔP closs And the active power loss change of the flexible DC cable ΔP CR , P WT0P is the active power delivered to the flexible direct current by the offshore wind turbine when the offshore wind power flexible direct current grid-connected system is operating normally. WT1 is the active power delivered to the flexible direct current by the offshore wind power flexible direct current grid-connected system after the disturbance occurs, ΔP WT The total power provided by the offshore wind turbine through inertia and droop control, P VSC1loss0 and P VSC1loss1 is the loss of the flexible DC receiving end converter before and after the disturbance, P VSC2loss0 and P VSC2loss1 is the loss of the flexible DC sending end converter before and after the disturbance, P CR0 and P CR1 is the loss of the flexible DC cable before and after the disturbance, I VSC1 and I VSC0 They are the magnitude of the DC current of the flexible DC after the disturbance and the magnitude of the DC current of the flexible DC before the disturbance, respectively. The coefficient a 1 and coefficient a 2 is the secondary loss coefficient of the flexible DC receiving and sending converters, and the coefficient b 1 and coefficient b 2 is the primary loss coefficient of the flexible DC receiving and sending converters, and the coefficient c 1 and coefficient c 2 is the constant loss coefficient of the flexible DC receiving and sending converters.

[0136] Step 4, combining the active frequency support of the offshore wind turbine, the change in active power loss of the flexible direct current and the frequency response model of the traditional power system, to obtain a frequency response model containing active frequency support for offshore wind power established in the offshore wind power flexible direct current grid-connected system.

[0137] Optionally, in one embodiment of the present invention, step 4 specifically includes:

[0138] Step 4-1, integrating the frequency response model of offshore wind power active frequency support and traditional power system:

[0139] Through the system frequency deviation and the system frequency change rate, the total power ΔP provided by the offshore wind turbine through inertia control and droop control is obtained. WT , and ΔP WT Adding it to the frequency response model of the traditional power system, we get the frequency response model including active frequency support of wind turbines, such as Figure 5 As shown:

[0140]

[0141] Step 4-2, the frequency response model including active frequency support for offshore wind power consists of the frequency response model of the traditional power system and the frequency response model including active frequency support for wind turbines. The frequency response model of the traditional power system adopts a simplified low-order frequency response model, and the active frequency support control of the wind turbine adopts a comprehensive inertia control combining inertia control and droop control. At the same time, the loss changes in the process of flexible direct current transmission of active power are considered, and finally the frequency response model including active frequency support for offshore wind power of the offshore wind power flexible direct current grid-connected system is established, such as Figure 6 As shown:

[0142]

[0143] Where ΔP d It is active disturbance.

[0144] The method for establishing the frequency response model of the offshore wind power flexible direct current grid-connected system of the present invention is described in detail below through the accompanying drawings and specific embodiments.

[0145] In PSCAD / EMTDC simulation software, Figure 7 The simulation model shown in the figure. The model used is composed of two wind turbines with a steady-state output of 360MW active power, which are connected to the MMC-HVDC through two 33 / 230kV AC transformers, with a DC voltage level of ±320kV, and then connected to a simple AC system consisting of a synchronous motor and related loads. The model frequency is set to 50Hz, the synchronous motor has a steady-state output of 520MW, the inertia time constant is 6.5s, and the DC voltage level of the flexible DC is ±320kV. Set the initial active load P of the system L The loss coefficients a, b, c of the flexible DC receiving converter are 1.323×10-5, -9.524×10-4, 3.7 respectively, and the loss coefficients a, b, c of the flexible DC sending converter are 1.764×10-5, -1.825×10-3, 0.3 respectively.

[0146] In order to verify that the present invention can simulate the frequency response characteristics of the offshore wind power system after system disturbance under the condition of flexible direct current grid connection, the working conditions are set as follows:

[0147] Condition 1: Offshore wind power does not provide active frequency support, and an active load disturbance of 80MW occurs at node 2 at 50s.

[0148] Without considering the active frequency control strategy of the fan, the SFR model is constructed. Figure 8A comparison of the frequency response curves of the SFR model and the detailed model when active frequency support is not included in offshore wind power is given. After the disturbance occurs, the lowest frequency point of the detailed model is 49.672Hz, while the lowest frequency point of the SFR model is 49.658Hz. At the same time, the system frequencies of the detailed model and the SFR model are both stable at 49.85Hz after the transient process, indicating that the constructed SFR model can basically describe the changes in the system frequency response after the disturbance.

[0149] Condition 2: Offshore wind power uses integrated inertial control to provide active frequency support, and an 80MW active load disturbance occurs at node 2 at 50s. Considering the active frequency support provided by offshore wind power and the losses in flexible direct current transmission, the verification of the frequency response model is as follows: Fig. 9 shown.

[0150] By comparison, it can be seen that due to the active frequency support of offshore wind power, an 80MW active disturbance also occurred at 50s, and the lowest frequency point rose to 49.807Hz. The constructed frequency response model takes into account the active frequency support of offshore wind power and the loss changes during flexible direct current transmission, and the lowest frequency point is 49.800Hz, which can more accurately consider the active frequency support of offshore wind power, verifying the effectiveness and accuracy of the SFR model of the wind turbine with active frequency support proposed in this invention.

[0151] Taking into account the frequency response of the loss changes in flexible DC transmission, considering the active frequency support of offshore wind power through comprehensive inertial control, the losses in flexible DC transmission are calculated. In order to analyze the impact of the loss changes in flexible DC transmission on the frequency response, Fig.10 The changes in losses during the flexible direct current transmission of wind power output after the active frequency support of offshore wind power changes the output are given. It can be seen that after the active power generation disturbance occurs at 50s, due to the active frequency support of offshore wind power, the power of flexible direct current transmission increases, and the losses generated during the flexible direct current transmission process will also increase.

[0152] The frequency response curve of the SFR model considering the flexible direct current transmission loss is compared with the frequency response curve of the SFR model not considering the flexible direct current transmission loss. Fig.11 To quantify the accuracy of the SFR model with wind turbines proposed in this paper, the error rate e% is defined as follows:

[0153]

[0154] In the formula, f SFR , f sys are the frequencies obtained by the proposed SFR model and the detailed model respectively; N sis the total number of samples; subscript s is the sampling time. According to the simulation results, the error rate of the SFR model considering the flexible DC transmission loss is 0.108%, and the error rate of the SFR model without considering the flexible DC transmission loss is 0.208%. The frequency response obtained by the SFR model considering the flexible DC transmission loss is closer to the detailed model, which can more accurately simulate the frequency response characteristics of the offshore wind power flexible DC grid-connected system, and at the same time reflect the influence of the active frequency control strategy on the system frequency modulation, and the overall accuracy of the obtained frequency response characteristics has been improved.

[0155] Next, a device for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system proposed in accordance with an embodiment of the present invention will be described with reference to the accompanying drawings.

[0156] Fig.12 A structural block diagram of a device for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system provided according to an embodiment of the present invention.

[0157] like Fig.12 As shown, the device 10 for establishing the frequency response model of the offshore wind power flexible direct current grid-connected system includes:

[0158] The first establishment module 100 is used to establish a frequency response model of a traditional power system with a reheat steam turbine generator as an object;

[0159] The second building module 200 is used to build a comprehensive inertial control model combining inertial control and droop control of an offshore wind turbine;

[0160] The calculation module 300 is used to calculate the change in the active power loss of the flexible direct current in combination with the comprehensive inertial control model of the offshore wind turbine;

[0161] The third establishment module 400 is used to combine the active frequency support of the offshore wind turbine, the change in active power loss of the flexible direct current and the frequency response model of the traditional power system to obtain a frequency response model containing active frequency support for offshore wind power established in the offshore wind power flexible direct current grid-connected system.

[0162] Optionally, in one embodiment of the present invention, the first establishing module 100 is specifically used for:

[0163] Taking the reheat steam turbine generator as the object, the governor-prime mover mathematical model is established and simplified. The simplified governor-prime mover model is combined with the rotor motion equation to obtain the frequency response model of the traditional power system:

[0164]

[0165] In the formula, H s and D are the inertia time constant and damping coefficient of the synchronous generator, respectively, K mis the coefficient related to the synchronous generator power factor and reserve capacity, F H is the work ratio of the high-pressure cylinder in the reheat turbine generator, T R is the reheat time constant of the reheat turbine generator, R is the speed regulator adjustment factor, Δf is the frequency deviation, ΔP d is the active disturbance, ΔP m is the equivalent mechanical power increment caused by frequency change, G s (s) is the frequency response model of the traditional power system.

[0166] Optionally, in one embodiment of the present invention, the second establishing module 200 is specifically used for:

[0167] Droop control is added to the offshore wind turbine; the droop control uses the frequency deviation to simulate the governor response of the synchronous generator, and the formula is:

[0168] ΔP dr =-K dr Δf

[0169] Where ΔP dr Frequency support power provided by droop control for offshore wind turbines, K dr is the droop control coefficient, Δf is the frequency deviation;

[0170] Inertial control is added to offshore wind turbines; the purpose of inertial control is to simulate the inertial response process of conventional synchronous generators and use the grid frequency change rate as the input signal of additional power control to adjust the power output of offshore wind turbines. The formula is:

[0171]

[0172] Where ΔP in Frequency support power provided by inertial control for offshore wind turbines, K in is the inertia control coefficient;

[0173] In the additional control of offshore wind turbines, integrated inertia control is added. The integrated inertia control includes inertia control and droop control of offshore wind turbines. The integrated inertia control model of offshore wind turbines is specifically expressed as follows:

[0174]

[0175] Where ΔP WT The total power provided by the offshore wind turbine through inertia and droop control, f ref is the reference value of frequency, and f is the actual measured frequency.

[0176] Optionally, in one embodiment of the present invention, the calculation module 300 is specifically used for:

[0177] Calculate the active power loss of flexible DC cable:

[0178]

[0179] Where P CR is the active power loss of the flexible DC cable, I VSC is the DC current of the flexible DC, R is the equivalent resistance of the flexible DC transmission line, U dc is the soft DC voltage, P WT The amount of active power delivered to the flexible DC power supply to the wind turbine;

[0180] Calculate the active power loss of the flexible DC converter:

[0181]

[0182] Where P closs It is the sum of the active power loss of VSC caused by the conduction loss and switching loss of power electronic devices. The coefficient a simulates the loss that is linearly related to the square of the active power delivered by the wind turbine to the flexible DC, the coefficient b simulates the loss that is linearly related to the active power delivered by the wind turbine to the flexible DC, and the coefficient c simulates the fixed loss.

[0183] According to the active power loss of the flexible DC cable and the active power loss of the flexible DC converter, combined with the comprehensive inertia control model of the offshore wind turbine, the change in the active power loss of the flexible DC is calculated:

[0184]

[0185] In the formula, the change in active power loss of flexible DC is ΔP loss Including the active power loss change of the flexible DC converter ΔP closs And the active power loss change of the flexible DC cable ΔP CR , P WT0 P is the active power delivered to the flexible direct current by the offshore wind turbine when the offshore wind power flexible direct current grid-connected system is operating normally. WT1 is the active power delivered to the flexible direct current by the offshore wind power flexible direct current grid-connected system after the disturbance occurs, ΔP WT The total power provided by the offshore wind turbine through inertia and droop control, P VSC1loss0 and P VSC1loss1 is the loss of the flexible DC receiving end converter before and after the disturbance, P VSC2loss0 and P VSC2loss1 is the loss of the flexible DC sending end converter before and after the disturbance, P CR0 and P CR1is the loss of the flexible DC cable before and after the disturbance, I VSC1 and I VSC0 They are the magnitude of the DC current of the flexible DC after the disturbance and the magnitude of the DC current of the flexible DC before the disturbance, respectively. The coefficient a 1 and coefficient a 2 is the secondary loss coefficient of the flexible DC receiving and sending converters, and the coefficient b 1 and coefficient b 2 is the primary loss coefficient of the flexible DC receiving and sending converters, and the coefficient c 1 and coefficient c 2 is the constant loss coefficient of the flexible DC receiving and sending converters.

[0186] Optionally, in one embodiment of the present invention, the third establishing module 400 is specifically used to:

[0187] Frequency response model of integrated offshore wind power active frequency support and traditional power system:

[0188] Through the system frequency deviation and the system frequency change rate, the total power ΔP provided by the offshore wind turbine through inertia control and droop control is obtained. WT , and ΔP WT Adding it to the frequency response model of the traditional power system, we get the frequency response model including active frequency support of wind turbines:

[0189]

[0190] The frequency response model including active frequency support for offshore wind power consists of the frequency response model of the traditional power system and the frequency response model including active frequency support for wind turbines. The frequency response model of the traditional power system adopts a simplified low-order frequency response model. The active frequency support control of wind turbines adopts a comprehensive inertia control combining inertia control and droop control. At the same time, the loss changes in the process of flexible direct current transmission of active power are considered. Finally, the frequency response model including active frequency support for offshore wind power is established:

[0191]

[0192] In the formula, ΔP d It is active disturbance.

[0193] It should be noted that the aforementioned explanation of the embodiment of the method for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system is also applicable to the device for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system of this embodiment, and will not be repeated here.

[0194] According to the method and device for establishing the frequency response model of the offshore wind power flexible direct current grid-connected system proposed in the embodiment of the present invention, for the offshore wind power flexible direct current grid-connected system, the active frequency support of offshore wind power is added to the frequency response model of the traditional system, and the changes in the losses generated during the flexible direct current transmission process are considered in the frequency response model, which can accurately reflect the frequency response characteristics of wind power after the system disturbance under the condition of flexible direct current grid-connected. The present invention can consider the active frequency support of offshore wind power, and at the same time calculate the changes in the losses generated during the flexible direct current transmission of active power, and obtain the frequency response model of the power system containing the offshore wind power flexible direct current grid-connected. The frequency response model can accurately evaluate the frequency response characteristics of offshore wind power after the system disturbance under the condition of flexible direct current grid-connected, and provide an important reference for the frequency control and stable operation of the power system.

[0195] Fig.13 A schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. The electronic device may include:

[0196] A memory 1301 , a processor 1302 , and a computer program stored in the memory 1301 and executable on the processor 1302 .

[0197] When the processor 1302 executes the program, the method for establishing the frequency response model of the offshore wind power flexible direct current grid-connected system provided in the above embodiment is implemented.

[0198] Furthermore, the electronic device further comprises:

[0199] The communication interface 1303 is used for communication between the memory 1301 and the processor 1302 .

[0200] The memory 1301 is used to store computer programs that can be executed on the processor 1302 .

[0201] The memory 1301 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0202] If the memory 1301, the processor 1302 and the communication interface 1303 are implemented independently, the communication interface 1303, the memory 1301 and the processor 1302 can be connected to each other through a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Fig.13 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0203] Optionally, in a specific implementation, if the memory 1301, the processor 1302 and the communication interface 1303 are integrated on a chip, the memory 1301, the processor 1302 and the communication interface 1303 can communicate with each other through an internal interface.

[0204] The processor 1302 may be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present invention.

[0205] This embodiment also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system as described above.

[0206] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0207] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "N" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0208] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present invention belong.

Claims

1. A method for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system, characterized in that: The following steps are involved: Taking the reheat steam turbine generator as the object, the frequency response model of the traditional power system is established; Establish a comprehensive inertial control model combining inertial control and droop control for offshore wind turbines; Combined with the comprehensive inertial control model of offshore wind turbines, the change in active power loss of flexible direct current is calculated; By combining the active frequency support of offshore wind turbines, the change in active power loss of flexible direct current (DC) and the frequency response model of traditional power systems, a frequency response model containing active frequency support for offshore wind power established in the offshore wind power flexible direct current (DC) grid-connected system is obtained.

2. The method according to claim 1, characterized in that The frequency response model of the traditional power system established by taking the reheat steam turbine generator as the object specifically includes: Taking the reheat steam turbine generator as the object, the governor-prime mover mathematical model is established and simplified. The simplified governor-prime mover model is combined with the rotor motion equation to obtain the frequency response model of the traditional power system: In the formula, H s and D are the inertia time constant and damping coefficient of the synchronous generator, respectively, K m is the coefficient related to the synchronous generator power factor and reserve capacity, F H is the work ratio of the high-pressure cylinder in the reheat turbine generator, T R is the reheat time constant of the reheat turbine generator, R is the speed regulator adjustment factor, Δf is the frequency deviation, ΔP d is the active disturbance, ΔP m is the equivalent mechanical power increment caused by frequency change, G s (s) is the frequency response model of the traditional power system.

3. The method according to claim 2, characterized in that The establishment of a comprehensive inertial control model combining inertial control and droop control of an offshore wind turbine generator set specifically includes: Incorporating droop control in offshore wind turbines; Among them, the droop control uses the frequency deviation to simulate the governor response of the synchronous generator, and the formula is: ΔP dr =-K dr Δf Where ΔP dr Frequency support power provided by droop control for offshore wind turbines, K dr is the droop control coefficient, Δf is the frequency deviation; Adding inertial control to offshore wind turbines; The purpose of inertial control is to simulate the inertial response process of conventional synchronous generators and use the grid frequency change rate as the input signal of additional power control to adjust the power output of offshore wind turbines. The formula is: In the formula, ΔP in Frequency support power provided by inertial control for offshore wind turbines, K in is the inertia control coefficient; Adding integrated inertia control to the additional control of offshore wind turbines, the integrated inertia control includes inertia control and droop control of offshore wind turbines; Among them, the comprehensive inertial control model of offshore wind turbines is specifically expressed as: Where ΔP WT The total power provided by the offshore wind turbine through inertia and droop control, f ref is the reference value of frequency, and f is the actual measured frequency.

4. The method according to claim 3, characterized in that The calculation of the change in the active power loss of the flexible direct current in combination with the comprehensive inertia control model of the offshore wind turbine generator set specifically includes: Calculate the active power loss of flexible DC cable: Where P CR is the active power loss of the flexible DC cable, I VSC is the DC current of the flexible DC, R is the equivalent resistance of the flexible DC transmission line, U dc is the soft DC voltage, P WT The amount of active power delivered to the flexible DC power supply to the wind turbine; Calculate the active power loss of the flexible DC converter: Where P closs It is the sum of the active power loss of VSC caused by the conduction loss and switching loss of power electronic devices. The coefficient a simulates the loss that is linearly related to the square of the active power delivered by the wind turbine to the flexible DC, the coefficient b simulates the loss that is linearly related to the active power delivered by the wind turbine to the flexible DC, and the coefficient c simulates the fixed loss. According to the active power loss of the flexible DC cable and the active power loss of the flexible DC converter, combined with the comprehensive inertia control model of the offshore wind turbine, the change in the active power loss of the flexible DC is calculated: In the formula, the change in active power loss of flexible DC is ΔP loss Including the active power loss change of the flexible DC converter ΔP closs And the active power loss change of the flexible DC cable ΔP CR , P WT0 P is the active power delivered to the flexible direct current by the offshore wind turbine when the offshore wind power flexible direct current grid-connected system is operating normally. WT1 is the active power delivered to the flexible direct current by the offshore wind power flexible direct current grid-connected system after the disturbance occurs, ΔP WT The total power provided by the offshore wind turbine through inertia and droop control, P VSC1loss0 and P VSC1loss1 is the loss of the flexible DC receiving end converter before and after the disturbance, P VSC2loss0 and P VSC2loss1 is the loss of the flexible DC sending end converter before and after the disturbance, P CR0 and P CR1 is the loss of the flexible DC cable before and after the disturbance, I VSC1 and I VSC0 are the DC current magnitude of the flexible DC after the disturbance and the DC current magnitude of the flexible DC before the disturbance, respectively. Coefficient a1 and coefficient a2 are the secondary loss coefficients of the flexible DC receiving and sending converters. Coefficient b1 and coefficient b2 are the primary loss coefficients of the flexible DC receiving and sending converters. Coefficient c1 and coefficient c2 are the constant loss coefficients of the flexible DC receiving and sending converters.

5. The method according to claim 4, characterized in that The active frequency support of the offshore wind turbines, the change in the active power loss of the flexible direct current and the frequency response model of the traditional power system are combined to obtain a frequency response model containing the active frequency support of offshore wind power established in the offshore wind power flexible direct current grid-connected system, which specifically includes: Frequency response model of integrated offshore wind power active frequency support and traditional power system: Through the system frequency deviation and the system frequency change rate, the total power ΔP provided by the offshore wind turbine through inertia control and droop control is obtained. WT , and ΔP WT Adding it to the frequency response model of the traditional power system, we get the frequency response model including active frequency support of wind turbines: The frequency response model including active frequency support for offshore wind power consists of the frequency response model of the traditional power system and the frequency response model including active frequency support for wind turbines. The frequency response model of the traditional power system adopts a simplified low-order frequency response model. The active frequency support control of wind turbines adopts a comprehensive inertia control combining inertia control and droop control. At the same time, the loss changes in the process of flexible direct current transmission of active power are considered. Finally, the frequency response model including active frequency support for offshore wind power is established: Where ΔP d It is active disturbance.

6. A device for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system, characterized in that: include: The first building module is used to build a frequency response model of a traditional power system with a reheat steam turbine generator as an object; The second building module is used to build a comprehensive inertial control model combining inertial control and droop control of offshore wind turbines; A calculation module is used to calculate the change in active power loss of the flexible direct current in combination with a comprehensive inertial control model of the offshore wind turbine; The third module is used to combine the active frequency support of offshore wind turbines, the change in active power loss of flexible direct current and the frequency response model of traditional power systems to obtain a frequency response model containing active frequency support for offshore wind power established in the offshore wind power flexible direct current grid-connected system.

7. The device according to claim 6, characterized in that The first establishing module is specifically used for: Taking the reheat steam turbine generator as the object, the governor-prime mover mathematical model is established and simplified. The simplified governor-prime mover model is combined with the rotor motion equation to obtain the frequency response model of the traditional power system: In the formula, H s and D are the inertia time constant and damping coefficient of the synchronous generator, respectively, K m is the coefficient related to the synchronous generator power factor and reserve capacity, F H is the work ratio of the high-pressure cylinder in the reheat turbine generator, T R is the reheat time constant of the reheat turbine generator, R is the speed regulator adjustment factor, Δf is the frequency deviation, ΔP d is the active disturbance, ΔP m is the equivalent mechanical power increment caused by frequency change, G s (s) is the frequency response model of the traditional power system.

8. The device according to claim 7, characterized in that The second establishing module is specifically used for: Droop control is added to the offshore wind turbine; the droop control uses the frequency deviation to simulate the governor response of the synchronous generator, and the formula is: ΔP dr =-K dr Δf In the formula, ΔP dr Frequency support power provided by droop control for offshore wind turbines, K dr is the droop control coefficient, Δf is the frequency deviation; Inertial control is added to offshore wind turbines; the purpose of inertial control is to simulate the inertial response process of conventional synchronous generators and use the grid frequency change rate as the input signal of additional power control to adjust the power output of offshore wind turbines. The formula is: Where ΔP in Frequency support power provided by inertial control for offshore wind turbines, K in is the inertia control coefficient; In the additional control of offshore wind turbines, integrated inertia control is added. The integrated inertia control includes inertia control and droop control of offshore wind turbines. The integrated inertia control model of offshore wind turbines is specifically expressed as follows: In the formula, ΔP WT The total power provided by the offshore wind turbine through inertia and droop control, f ref is the reference value of frequency, and f is the actual measured frequency.

9. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system as described in any one of claims 1 to 5.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement a method for establishing a frequency response model of an offshore wind power flexible direct current grid-connected system as described in any one of claims 1 to 5.

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