Frequency modulation parameter optimization setting method and device for offshore wind power flexible direct transmission system

Abstract

The application belongs to the field of electric power, and discloses a frequency modulation parameter optimization setting method and device for an offshore wind power flexible direct transmission system, which comprises the following steps: establishing a frequency response analysis model of the offshore wind power flexible direct transmission system according to the control topology of the offshore wind power flexible direct transmission system, and calculating an equivalent frequency support capability transfer function of the system; drawing a time / frequency domain curve of the frequency support capability through the equivalent frequency support capability transfer function, and determining the frequency modulation control parameters that have an influence on the frequency support capability of the system; and according to the evaluation results of the equivalent frequency support capability of the system, a system frequency modulation parameter optimization setting method based on a particle swarm algorithm is proposed from the dual perspectives of support strength and response speed. The method calculates the equivalent frequency support capability of the offshore wind power flexible direct transmission system, designs a frequency modulation parameter optimization setting method based on the particle swarm algorithm based on the evaluation results of the frequency support capability, and realizes the comprehensive optimization of the active support strength and response speed of the system frequency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electric power, in particular to a frequency modulation parameter optimization setting method and device for an offshore wind power flexible direct transmission system. BACKGROUND

[0002] In view of the large-scale offshore wind power transmission demand, the flexible direct current transmission technology has attracted widespread attention at home and abroad due to its strong controllability, large transmission capacity and independent network operation advantage. The offshore wind power flexible direct transmission system has become a key means for offshore wind power consumption. However, the receiving converter of the offshore wind power flexible direct transmission system usually adopts phase-locked synchronization, and does not have the frequency support capability of the receiving power grid. In order to ensure the frequency safety and stability of the power system, the offshore wind power flexible direct transmission system needs to have certain frequency modulation capability through inertia control strategy.

[0003] However, although the offshore wind power flexible direct transmission system can provide important power support for the power system, there is still room for optimization in its role in frequency regulation. Frequency modulation is the core of power system stability, and under the background of renewable energy sources such as wind power gradually becoming the main power source, the improvement of inertia support capability is particularly important. However, under the frequency disturbance of the power grid, there is a complex coupling between the transient support power of offshore wind turbines and the flexible direct current system, and the equivalent frequency support capability evaluation of the offshore wind power flexible direct current transmission system is challenging, which further leads to difficulty in optimizing the frequency support capability of the offshore wind power flexible direct transmission system. Therefore, it is urgent to evaluate the equivalent frequency support capability of the system, further optimize the frequency modulation parameters of the offshore wind power flexible direct transmission system, fully tap the support potential of the system, and improve the frequency support response speed and strength of the system. SUMMARY

[0004] Therefore, the embodiments of the present application provide a frequency modulation parameter optimization setting method and device for an offshore wind power flexible direct transmission system.

[0005] According to a first aspect of the embodiments of the present application, a frequency modulation parameter optimization setting method for an offshore wind power flexible direct transmission system is provided, characterized in that it comprises:

[0006] According to the control topology of the offshore wind power flexible direct transmission system, a frequency response analysis model of the offshore wind power flexible direct transmission system is established, the equivalent frequency support capability transfer function of the offshore wind power flexible direct transmission system is calculated by analogy with the frequency modulation support physical process of synchronous machines, and the frequency modulation control parameters that have an impact on the frequency support capability of the offshore wind power flexible direct transmission system are determined.

[0007] The time / frequency domain curve of the frequency support capability is drawn through the equivalent frequency support capability transfer function, and the frequency modulation control parameters that have an impact on the frequency support capability of the offshore wind power flexible direct transmission system are determined.

[0008] The frequency modulation control parameter is optimized and set based on a particle swarm algorithm, and in the parameter optimization process, the optimization degree of the support strength and response speed of the offshore wind power flexible sending-out system under the current parameter is comprehensively evaluated according to the time / frequency domain curve of the frequency support capability, as an iteration basis.

[0009] According to a second aspect of the embodiment of the application, an offshore wind power flexible sending-out system frequency modulation parameter optimization and setting device is provided, comprising:

[0010] An equivalent frequency support capability transfer function calculation module is configured to establish an offshore wind power flexible sending-out system frequency response analysis model according to the control topology of the offshore wind power flexible sending-out system, analogize the synchronous machine frequency modulation support physical process, and calculate the equivalent frequency support capability transfer function of the offshore wind power flexible sending-out system.

[0011] A frequency modulation control parameter selection module is configured to draw the time / frequency domain curve of the frequency support capability through the equivalent frequency support capability transfer function, and determine the frequency modulation control parameter that has an influence on the frequency support capability of the offshore wind power flexible sending-out system.

[0012] A frequency modulation control parameter optimization module is configured to optimize and set the frequency modulation control parameter based on a particle swarm algorithm, and in the parameter optimization process, the optimization degree of the support strength and response speed of the offshore wind power flexible sending-out system under the current parameter is comprehensively evaluated according to the time / frequency domain curve of the frequency support capability, as an iteration basis.

[0013] According to a third aspect of the embodiment of the application, an electronic device is provided, comprising:

[0014] A processor;

[0015] A memory for storing processor executable instructions;

[0016] The processor implements the steps of the method according to the first aspect by running the executable instructions.

[0017] According to a fourth aspect of the embodiment of the application, a computer readable storage medium is provided, which stores computer instructions, and the instructions are executed by a processor to implement the steps of the method according to the first aspect.

[0018] The technical scheme provided by the embodiment of the application can have the following beneficial effects:

[0019] From the above embodiments, the application establishes a frequency response analysis model of the offshore wind power flexible HVDC transmission system based on the perspective of internal potential equivalence, analyzes the power transmission path by analogy with the method of synchronous machines, and deduces the equivalent frequency support capability of the system. According to the quantitative evaluation results, the frequency modulation control parameters that have an impact on the frequency support capability of the offshore wind power flexible HVDC transmission system are determined through time / frequency domain curves. On this basis, from the dual perspectives of support strength and response speed, a system frequency modulation parameter optimization setting method based on the particle swarm optimization algorithm is proposed, which overcomes the problems of difficult evaluation of the frequency support effect of the offshore wind power flexible HVDC transmission system and insufficient basis for parameter setting. The application fully taps the support potential of the offshore wind power flexible HVDC transmission system by optimizing the system frequency modulation parameters, and comprehensively improves the frequency support response speed and strength of the system.

[0020] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the application. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings, which are incorporated into and form part of the specification, illustrate an embodiment consistent with the application and, together with the specification, serve to explain the principles of the application.

[0022] Figure 1 FIG. 1 is a flowchart of a frequency modulation parameter optimization setting method of an offshore wind power flexible HVDC transmission system provided by an exemplary embodiment.

[0023] Figure 2 FIG. 1 is a schematic diagram of a topology of an offshore wind power flexible HVDC transmission system provided by an exemplary embodiment.

[0024] Figure 3 FIG. 1 is a schematic diagram of a frequency response analysis model of an offshore wind power flexible HVDC transmission system provided by an exemplary embodiment.

[0025] Figure 4 FIG. 1 is a schematic diagram of a time domain equivalent frequency support capability calculation method of an offshore wind power flexible HVDC transmission system provided by an exemplary embodiment.

[0026] Figure 5 FIG. 1 is a schematic diagram of a time / frequency domain curve of an offshore wind power flexible HVDC transmission system provided by an exemplary embodiment.

[0027] Figure 6 FIG. 1 is a flowchart of parameter optimization setting of an offshore wind power flexible HVDC transmission system based on a particle swarm optimization algorithm provided by an exemplary embodiment.

[0028] Figure 7 FIG. 1 is a schematic diagram of a comparison of equivalent inertia time constants before and after optimization of an offshore wind power flexible HVDC transmission system provided by an exemplary embodiment.

[0029] Figure 8 is a block diagram of a frequency modulation parameter optimization setting device of an offshore wind power flexible direct transmission system according to an example embodiment. DETAILED DESCRIPTION

[0030] The example embodiments will be described in detail herein with reference to the attached drawings. In the following description, the same numbers are used to designate the same elements, unless otherwise indicated. The embodiments described in the following example embodiments are not representative of all embodiments consistent with the present application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the present application, as detailed in the appended claims.

[0031] The terminology used in the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used in the present application and the appended claims, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0032] It is to be understood that although the terms first, second, third, etc. can be employed in this application to describe various information, such information should not be limited by these terms. These terms are only used to distinguish one piece of information from another. For example, a first information can be termed a second information without departing from the scope of the present application. Similarly, a second information can be termed a first information. The word "if' as used herein means "when" or "upon" or "in response to the determination" depending on the context.

[0033] Figure 1 is a flow chart of a frequency modulation parameter optimization setting method of an offshore wind power flexible direct transmission system according to an example embodiment, as shown in Figure 1 The method can include the following steps:

[0034] S1: According to the control topology of the offshore wind power flexible direct transmission system, a frequency response analysis model of the offshore wind power flexible direct transmission system is established, and an equivalent frequency support capability transfer function of the offshore wind power flexible direct transmission system is calculated by analogy with the synchronous machine frequency modulation support physical process;

[0035] Specifically, Figure 2This is a schematic diagram of the topology of an offshore wind power flexible DC transmission system provided in an exemplary embodiment. The offshore wind power flexible DC transmission system includes an offshore wind farm and a flexible DC transmission system. The offshore wind farm includes a turbine-side converter and a grid-side converter, and the flexible DC transmission system includes a receiving-end converter and a sending-end converter. The frequency response analysis model of the offshore wind power flexible DC transmission system includes: a frequency response analysis model of the offshore wind farm and a frequency response analysis model of the flexible DC transmission system.

[0036] Taking into account the speed control of the offshore wind turbine-side converter, the constant DC voltage control of the grid-side converter, and additional... df / dt Virtual inertia control can yield frequency response analysis models for offshore wind farms, such as... Figure 3 As shown in the dashed diagram, the frequency response analysis model of the offshore wind farm can be described as follows:

[0037] ;

[0038] in, s The Laplace operator is used, where Δ represents the small semaphore of the variable. P e,OWF The active power output of offshore wind power. pll For the phase-locked loop phase of the grid-side converter, G OWF ( s ) is ∆ P e,OWF With ∆ pll The transfer function between them.

[0039] The G OWF ( s This can be represented as:

[0040] ;

[0041] The expressions for each item are as follows:

[0042] ;

[0043] ;

[0044] Similar to the frequency response modeling of offshore wind farms, a frequency response analysis model for flexible DC transmission systems is established, such as... Figure 3 As shown in the solid line diagram. Since frequency support is typically a second-level process, belonging to the electromechanical time scale, and therefore... Figure 2It can be seen that the deviation of the grid-side converter phase-locked frequency of the offshore wind farm from the phase-locked frequency of the receiving-end HVDC converter is caused by the amplitude / frequency control of the sending-end HVDC converter and the constant DC voltage control of the receiving-end HVDC converter, and the bandwidths of the above two controls are about 10 Hz, and the delay caused by the above two controls can be ignored in the electromechanical time scale. Therefore, the grid-side converter phase-locked frequency of the offshore wind farm can be considered to be consistent with the phase-locked frequency of the receiving-end HVDC converter, and the grid-side converter phase-locked phase deviation can be considered to be consistent with the phase-locked phase deviation of the receiving-end HVDC converter. Therefore, the frequency response analysis model of the offshore wind farm HVDC sending-out system can be established by combining the frequency response analysis model of the flexible HVDC transmission system and the transfer function of the offshore wind farm as shown in Figure 3 .

[0045] As shown in Figure 3 , considering the frequency response analysis model of the flexible HVDC transmission system and combining the transfer function of the offshore wind farm G OWF ( s ), the frequency response analysis model of the offshore wind farm HVDC sending-out system is:

[0046] ;

[0047] wherein,

[0048] ;

[0049] ;

[0050] wherein, P e is the output active power of the offshore wind farm HVDC sending-out system, ctrl is the power control angle of the internal potential, E is the phase of the internal potential of the receiving-end HVDC converter, G ctrl1 , G ctrl2 is the transfer function between Δ P e and Δ ctrl , G pll1 , G pll2 is the transfer function between Δ P e and Δ pll , G pll ( s ) is the phase-locked loop transfer function, G 1( s )- G6( s ) is an intermediate transfer function used for simplification. E 0 represents the steady-state value of the internal potential. U t0 This is the steady-state value of the terminal voltage. X f For filter reactance, C It is a DC capacitor. U dc0 This represents the steady-state value of the DC line voltage. k p,dc This refers to the proportional gain of the DC voltage controller. k i,dc The integral coefficient of the DC voltage controller. k p,pll This is the proportional gain of the phase-locked loop. k i,pll The integral coefficients of the phase-locked loop are... K 1 represents the droop coefficient of the receiving-end converter.

[0051] In one embodiment, based on the frequency response analysis model of the offshore wind power flexible direct transmission system, the transfer function of the equivalent frequency support capability of the offshore wind power flexible direct transmission system is calculated as follows:

[0052] ;

[0053] in, 0 represents the steady-state value of the angular velocity of the internal potential of the receiving-end flexible DC converter. J total ( s ) is the transfer function of the equivalent frequency support capability of the sea breeze flexible straight system.

[0054] By analogy with the physical process of frequency modulation response of a synchronous machine, the frequency response process of the offshore wind power flexible direct transmission system is decomposed into two parts: the flexible direct transmission system and the offshore wind power. By analogy with the inertial response of a synchronous machine and the primary frequency modulation process, the equivalent relationship between the two is explored, and the equivalent frequency support capability of the offshore wind power flexible direct transmission system is accurately assessed.

[0055] S2: Plot the time / frequency domain curve of the frequency support capability using the equivalent frequency support capability transfer function, and determine the frequency regulation control parameters that affect the frequency support capability of the offshore wind power flexible direct transmission system;

[0056] Specifically, based on the equivalent frequency support capability transfer function, the frequency support capability Bode plot can be directly drawn, such as... Figure 5 As shown in (a) of the diagram. The larger the amplitude of the equivalent frequency support capability transfer function, the greater the system inertia, and the stronger its ability to generate active power during the frequency response process. The more the phase leads in the phase-frequency curve, the faster the system's response speed.

[0057] according toFigure 4 The time-domain equivalent frequency support capability calculation method shown in f r The product of the steady-state value of the angular velocity and the rate of change of the angular velocity is calculated, and since the frequency disturbance is in the form of a ramp, the rate of change of the angular velocity is constant. A step input of a corresponding size is given to the equivalent frequency support capability transfer function, and the step response result obtained is the output active power. The equivalent frequency support capability is further calculated as:

[0058] ;

[0059] wherein, J ( t ) is the time-domain equivalent frequency support capability, t is the time, P in is the input active power of the offshore wind power, P e is the output active power of the offshore wind power flexible HVDC transmission system, is the angular velocity of the internal potential of the receiving-end HVDC converter.

[0060] According to the time-domain equivalent frequency support capability calculation method shown in Figure 4 , the time-domain curve of the equivalent frequency support capability can be obtained as shown in (b) of Figure 5 . The size and response speed of the frequency support capability are key indicators for evaluating the frequency response characteristics. According to the time / frequency domain curve of the equivalent frequency support capability, the changes in the size and response speed of the equivalent frequency support capability under the changes of different control parameters are compared, and the frequency modulation control parameters that have an impact on the frequency support capability of the offshore wind power flexible HVDC transmission system are determined. The frequency modulation control parameters can include the phase-locked loop proportional coefficient k p,pll , the integral coefficient k i,pll , the speed control loop proportional coefficient k p,w , the integral coefficient k i,w , the DC voltage control loop proportional coefficient k p,dc , the integral coefficient k i,dc , the virtual inertia control coefficient K f , the low-pass filter time constant T f , and the receiving-end converter droop coefficient K 1.

[0061] Based on the equivalent frequency support capability evaluation results, the time / frequency domain curves of the equivalent frequency support capability of the offshore wind power flexible HVDC transmission system are drawn, the time / frequency domain characteristics of the equivalent support capability can be intuitively analyzed, the influence of the frequency modulation control parameters on the frequency support capability of the offshore wind power flexible HVDC transmission system can be evaluated from the frequency support capability size and response speed, and the influence law of the frequency modulation control parameters on the equivalent inertia is clarified.

[0062] S3: based on the particle swarm algorithm, the frequency modulation control parameters are optimized and set, in the parameter iteration optimization process, the optimization degree of the offshore wind power flexible HVDC transmission system support strength and response speed under the current parameters is evaluated according to the time / frequency domain curve of the frequency support capability, which is used as the iteration basis;

[0063] Specifically, the fitness function FF of the particle swarm algorithm is:

[0064] ;

[0065] Wherein, J norm is the normalized low-frequency equivalent frequency support capability amplitude, T norm is the normalized system response time, is the weight coefficient of the system frequency support capability support size, is the weight coefficient of the system response time.

[0066] The low-frequency equivalent frequency support capability amplitude and the system response time are different in dimension, in order to avoid the large numerical characteristics dominating the particle swarm algorithm iteration, the two are scaled to the same scale through normalization.

[0067] The normalized low-frequency equivalent frequency support capability amplitude is calculated by the equivalent frequency support capability frequency domain curve, which is used to evaluate the support strength of the equivalent frequency support capability, and the specific calculation formula is:

[0068] ;

[0069] Wherein, J min is the minimum value of the integral average of the system equivalent frequency support capability transfer function amplitude, J max is the maximum value of the integral average of the system equivalent frequency support capability transfer function amplitude.

[0070] The normalized system response time is calculated by the equivalent frequency support capability time domain curve, which is used to evaluate the equivalent frequency support response speed, and the specific calculation formula is:

[0071] ;

[0072] wherein, t 0.1 time required for the system equivalent frequency support capability to rise from 0 to 90% of the peak value, t 0.9 time required for the system equivalent frequency support capability to rise from 0 to 90% of the peak value, T min minimum value of the system response time, T max maximum value of the system response time.

[0073] Optionally, by introducing a second derivative square sum penalty term, excessive fluctuations of the curve in the optimization process are suppressed, the equivalent frequency support capability curve is smoother, and the system is more stable.

[0074] Since the equivalent frequency support capability time-domain curve can intuitively reflect the fluctuation of the equivalent frequency support capability when the system is unstable, the second derivative square sum penalty term is calculated by the equivalent frequency support capability time-domain curve, and the second derivative is approximated by the second difference, and the specific calculation formula is:

[0075]

[0076] wherein, is t i second derivative value of the time-domain equivalent frequency support capability at the moment, J t i is t i time-domain equivalent frequency support capability at the moment.

[0077] The second derivative square sum penalty term is:

[0078]

[0079] wherein, N is the number of sample points.

[0080] After the second derivative square sum penalty term is added, the fitness function is modified as:

[0081] ;

[0082] wherein, λ is a weight coefficient of the second derivative square sum penalty term.

[0083] Based on the equivalent frequency support capability of the offshore wind flexible system J total (s) time / frequency domain curve and particle swarm optimization algorithm, the frequency control parameter optimization setting method proposed in the present application is as follows​Figure 6 The specific steps are shown as follows: first, initializing particle swarm parameters, including particle swarm size / dimension, iteration number, inertia weight, position / speed of each particle, etc.; second, calculating the fitness function and judging whether it is the optimal value in the iteration range, if not, updating the particle swarm parameters according to the current fitness function and repeating the iteration process; and finally, outputting the optimal parameters in the iteration range.

[0084] The conventional parameters and optimized parameters of the offshore wind power flexible HVDC transmission system are shown in Table 1.

[0085] Table 1: Conventional parameters and optimized parameters of offshore wind power flexible HVDC transmission system

[0086]

[0087] Specifically, according to the Chinese power grid standard, the inertia time constant of wind turbine grid connection should not be less than 8s. The frequency modulation parameters of the offshore wind power flexible HVDC system calculated therefrom can be considered as the currently recognized conventional control parameters, as shown in the second column of Table 1. According to the proposed frequency modulation parameter optimization setting method of offshore wind power flexible HVDC transmission system, the optimized control parameters can be calculated, as shown in the third column of Table 1.

[0088] The comparison results of the equivalent inertia of the offshore wind power flexible HVDC system under the conventional and optimized control parameters are shown in Figure 7 It can be seen that the maximum value of the equivalent inertia time constant of the system under the conventional parameters is about 8s, which meets the grid standard; after optimization, the frequency response speed of the system is faster, and the support strength is improved.

[0089] A frequency modulation parameter optimization setting method based on particle swarm algorithm is designed, and the time / frequency domain curves of the equivalent frequency support capability of the offshore wind power flexible HVDC transmission system can directly reflect the effect of parameter optimization setting, which can effectively serve as the basis for iteration optimization of the particle swarm optimization algorithm, thereby fully tapping the support potential of the offshore wind power flexible HVDC transmission system and realizing the comprehensive optimization of the inertia support strength and response speed of the system.

[0090] From the above embodiments, it can be seen that the present application establishes a frequency response analysis model of the offshore wind power flexible HVDC transmission system from the perspective of internal potential equivalence, analyzes the power transmission path by analogy with synchronous machines, and deduces the equivalent frequency support capability of the system. According to the quantitative evaluation results, the frequency modulation control parameters that have an impact on the frequency support capability of the offshore wind power flexible HVDC transmission system are determined through time / frequency domain curves. On this basis, a system frequency modulation parameter optimization setting method based on particle swarm algorithm is proposed from the dual perspectives of support strength and response speed, which overcomes the problems of difficulty in evaluating the frequency support effect of the offshore wind power flexible HVDC transmission system and insufficient basis for parameter setting. The present application fully taps the support potential of the offshore wind power flexible HVDC transmission system by optimizing the system frequency modulation parameters, and comprehensively improves the frequency support response speed and strength of the system.

[0091] Corresponding to the foregoing embodiments of the method for optimizing and setting frequency modulation parameters of the offshore wind power flexible direct transmission system, the application also provides an embodiment of a device for optimizing and setting frequency modulation parameters of the offshore wind power flexible direct transmission system.

[0092] Figure 8 is a block diagram of a device for optimizing and setting frequency modulation parameters of an offshore wind power flexible direct transmission system according to an exemplary embodiment. Referring to Figure 8 , the device comprises:

[0093] An equivalent frequency support capability transfer function calculation module 1 is configured to establish a frequency response analysis model of the offshore wind power flexible direct transmission system according to a control topology of the offshore wind power flexible direct transmission system, analogize a synchronous machine frequency modulation support physical process, and calculate an equivalent frequency support capability transfer function of the offshore wind power flexible direct transmission system.

[0094] A frequency modulation control parameter selection module 2 is configured to draw a time / frequency domain curve of frequency support capability through the equivalent frequency support capability transfer function, and determine frequency modulation control parameters that have an influence on the frequency support capability of the offshore wind power flexible direct transmission system.

[0095] A frequency modulation control parameter optimization module 3 is configured to optimize and set the frequency modulation control parameters based on a particle swarm algorithm, and in the parameter optimization process, comprehensively evaluate the optimization degree of the support strength and response speed of the offshore wind power flexible direct transmission system under the current parameters according to the time / frequency domain curve of the frequency support capability, as an iteration basis.

[0096] As to the device in the above-described embodiments, the specific manner in which each module performs operations has been described in detail in the embodiments of the method, and will not be described here in detail.

[0097] For the device embodiments, since they basically correspond to the method embodiments, the related parts can be referred to the part of the method embodiments. The device embodiments described above are merely illustrative, wherein the units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, i.e., they can be located in one place, or distributed on multiple network units. Part or all of the modules can be selected to achieve the purposes of the application scheme according to actual needs. Those skilled in the art can understand and implement it without creative labor.

[0098] Correspondingly, the application further provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors implement the frequency modulation parameter optimization setting method of the offshore wind power flexible direct transmission system as described above.

[0099] Correspondingly, the application further provides a computer readable storage medium, which stores computer instructions, and the instructions are executed by a processor to implement the frequency modulation parameter optimization setting method of the offshore wind power flexible direct transmission system as described above.

[0100] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the following claims.

[0101] It should be understood that the application is not limited to the precise construction that has been described above and shown in the accompanying drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the application. The scope of the application is limited only by the appended claims.

Claims

1. A method for optimizing setting of frequency modulation parameters of a marine wind power flexible direct transmission system, characterized in that, The method comprises the following steps: According to the control topology of the offshore wind power flexible direct transmission system, an offshore wind power flexible direct transmission system frequency response analysis model is established, and the equivalent frequency support capability transfer function of the offshore wind power flexible direct transmission system is calculated by analogy to the frequency modulation support physical process of a synchronous machine; The time domain and frequency domain curves of the frequency support capability are drawn through the equivalent frequency support capability transfer function, and the frequency modulation control parameters that have an impact on the frequency support capability of the offshore wind power flexible direct transmission system are determined; The particle swarm algorithm is used to optimize and set the frequency modulation control parameters, and in the parameter optimization process, the optimization degree of the support strength and response speed of the offshore wind power flexible direct transmission system under the current parameters is comprehensively evaluated according to the time domain and frequency domain curves of the frequency support capability, which is used as the iteration basis.

2. The method of claim 1, wherein, The offshore wind power flexible direct transmission system frequency response analysis model is: ； Wherein, ； ； wherein s is the Laplace operator, Δ denotes a small-signal quantity of a variable, P e is the output active power of the offshore wind farm flexible HVDC transmission system, P e,OWF is the output active power of the offshore wind farm, ctrl is the power control angle of the internal voltage, pll is the phase of the grid-side converter phase-locked loop, E is the phase of the internal voltage of the receiving-end HVDC converter, G ctrl1 , G ctrl2 is the transfer function between Δ P e and Δ ctrl , G pll1 , G pll2 is the transfer function between Δ P e and Δ pll , G OWF is the transfer function between Δ s ) and Δ P e,OWF , pll is the transfer function between Δ G pll , s is the phase-locked loop transfer function, G 1( s )- G 6( s ) is an intermediate transfer function for simplification, E 0 is the steady-state value of the internal voltage, U t0 is the steady-state value of the terminal voltage, X f is the filter reactance, C is the DC capacitance, U dc0 is the steady-state value of the DC line voltage, k p,dc is the proportional coefficient of the DC voltage controller, k i,dc is the integral coefficient of the DC voltage controller, k p,pll is the proportional coefficient of the phase-locked loop, k i,pll is the integral coefficient of the phase-locked loop, K 1 is the droop coefficient of the receiving converter.

3. The method of claim 2, wherein, The equivalent frequency support capability transfer function is: ； wherein 0 is the steady-state value of the angular speed of the internal potential of the receiving HVDC converter, is the angular speed of the internal potential of the receiving HVDC converter, J total ( s ) is the equivalent frequency support capability transfer function of the offshore HVDC system.

4. The method of claim 1, wherein, The time domain and frequency domain curves of the frequency support capability are drawn through the equivalent frequency support capability transfer function, and the frequency modulation control parameters that have an impact on the frequency support capability of the offshore wind power flexible direct transmission system are determined, which comprises: According to the equivalent frequency support capability transfer function, the frequency support capability Bode diagram, i.e. the equivalent frequency support capability frequency domain curve, is directly drawn; The step response result obtained by giving the equivalent frequency support capability transfer function a step input is the output active power, and then the time domain equivalent frequency support capability is calculated; The equivalent frequency support capability time domain curve is drawn according to the time domain equivalent frequency support capability; The frequency modulation control parameters that have an impact on the equivalent frequency support capability are determined according to the equivalent frequency support capability frequency domain curve and the equivalent frequency support capability time domain curve.

5. The method of claim 1, wherein, The time domain equivalent frequency support capability is calculated by the following formula: ； wherein J t is the time domain equivalent frequency support capability, t is the time, P in is the offshore wind farm input active power, 0 is the steady state value of the internal voltage angular speed of the receiving end flexible HVDC converter, is the internal voltage angular speed of the receiving end flexible HVDC converter.​ 6. The method of claim 1, wherein, The fitness function of the particle swarm algorithm is: ； In the formula, is a fitness function, is a weight coefficient of the support size of the system frequency support capability, J norm is a normalized low-frequency equivalent frequency support capability amplitude, is a weight coefficient of the system response time, T norm is a normalized system response time, The expression of the second derivative square penalty term is as follows: is a weight coefficient of the second derivative square sum penalty term; M is a second derivative square sum penalty term.

7. The method of claim 6, wherein, The method comprises the following steps: ； wherein, N is the number of sample points; ； wherein is t i the time-domain equivalent frequency support capability second derivative value at the time instant, J t i is t i the time-domain equivalent frequency support capability at the time instant.​ 8. A device for optimizing and setting frequency modulation parameters of a marine wind power flexible direct transmission and delivery system, characterized in that, An equivalent frequency support capability transfer function calculation module is configured to establish an offshore wind power flexible direct transmission system frequency response analysis model according to the control topology of the offshore wind power flexible direct transmission system, calculate the equivalent frequency support capability transfer function of the offshore wind power flexible direct transmission system by analogy to the frequency modulation support physical process of a synchronous machine; A frequency modulation control parameter selection module is configured to draw the time domain and frequency domain curves of the frequency support capability through the equivalent frequency support capability transfer function, and determine the frequency modulation control parameters that have an impact on the frequency support capability of the offshore wind power flexible direct transmission system; A frequency modulation control parameter optimization module is configured to optimize and set the frequency modulation control parameters based on the particle swarm algorithm, and in the parameter optimization process, the optimization degree of the support strength and response speed of the offshore wind power flexible direct transmission system under the current parameters is comprehensively evaluated according to the time domain and frequency domain curves of the frequency support capability, which is used as the iteration basis. The method comprises the following steps:

9. An electronic device, comprising: A processor; A memory for storing processor-executable instructions; The processor executes the executable instructions to implement the steps of the method according to any one of claims 1-7. The instructions are executed by the processor to implement the steps of the method according to any one of claims 1-7.

10. A computer readable storage medium having stored thereon computer instructions, wherein, ​

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