Method for analyzing power coupling characteristics of offshore wind farm based on relative gain array

Abstract

The application discloses a kind of offshore wind farm power coupling characteristic analysis methods based on relative gain array, belong to power electronic control technical field.The application first establishes the power stage small signal dynamic equation of offshore rectifier station, then establishes the power stage small signal dynamic equation of offshore wind turbine based on the control pairing and control parameter of preestablished;Finally, based on two power stage small signal dynamic equations, the power stage small signal model of offshore wind farm is established, and the relative gain typical value is obtained;According to the relative gain typical value, the active power and reactive power power coupling degree of offshore wind farm and whether control pairing and control parameter are reasonable are characterized.The method can be widely used in offshore wind turbine converters using follow network type and network type control strategy, using uncontrolled diode rectifier and full-controlled modular multilevel converter, etc.Form offshore rectifier station, realize the quantitative characterization of offshore wind farm coupling characteristics, and have guiding significance for the design or selection of control structure and controller parameters.

Description

Technical Field

[0001] This invention belongs to the field of power electronic control technology, specifically relating to a quantitative analysis method for the power coupling characteristics of offshore wind farms based on a relative gain array. Background Technology

[0002] Wind power, as a clean and renewable energy source, has seen rapid development and promotion in recent years. Currently, wind power resources in inland and nearshore areas of my country are maturing, while offshore wind power is gradually developing towards larger capacity units and further from the coast, becoming a new growth point for my country's wind power industry. With the continuous increase in wind power transmission capacity and the increasing distance of offshore wind farms from the shore, schemes such as all-DC collection and transmission, low-frequency collection and transmission, and medium-frequency collection and transmission have gradually become alternatives to traditional offshore wind farm AC collection and transmission due to their economic efficiency and reliability. With the diversification of offshore wind farm collection schemes, the equipment forms for connecting offshore wind energy to the offshore common coupling point are becoming increasingly complex, breaking the traditional typical architecture of wind turbines connected to grid-side converters and then connected to modular multilevel converter stations for DC transmission. For example, on the wind turbine side of the offshore common coupling point, the wind turbine grid-side converter may adopt a grid-connected control structure or a grid-connected control structure; on the transmission side of the offshore common coupling point, the offshore rectifier station may use modular multilevel converters, thyristor semi-controlled rectifiers, diode uncontrolled rectifiers, and other transmission equipment.

[0003] Power transmission control at the common coupling point (CCP) is crucial for offshore wind farm operation. However, the diverse forms and complex characteristics of equipment connected to the CCP make the active and reactive power coupling characteristics between offshore wind turbines and power transmission equipment at the CCP more complex. Currently, the analysis of power transmission and coupling characteristics in offshore wind farms is based on the steady-state power transmission equation at the CCP. By deriving and calculating the partial derivatives of steady-state active and reactive power with respect to voltage and frequency, and analyzing the signs and trends of the four partial derivative functions, the power loop control pairing of the offshore wind turbine converter is determined. However, this method struggles to quantitatively characterize the dynamic power coupling mechanism of offshore wind farms and directly calculate the degree of power coupling, thus hindering the design of power transmission control schemes. Furthermore, since equipment control parameters closely affect power control performance, traditional methods are also insufficient to effectively assess the rationality of control parameters. Summary of the Invention

[0004] To address the problems in the prior art, this invention provides a method for analyzing the power coupling characteristics of offshore wind fields based on a relative gain array.

[0005] The technical solution adopted in this invention is as follows:

[0006] In a first aspect, the present invention discloses a method for analyzing the power coupling characteristics of offshore wind fields based on a relative gain array, comprising the following steps:

[0007] 1) Based on the amplitude and frequency of the phase voltage on the AC side of the offshore rectifier station and the active and reactive power absorbed by the offshore rectifier station, establish the small-signal dynamic equation of the power level of the offshore rectifier station in the complex frequency domain.

[0008] 2) Control the offshore wind turbine based on the preset control pairing and control parameters; and establish the small-signal dynamic equation of the power stage of the offshore wind turbine based on the active power and reactive power output of the offshore wind turbine under the current conditions, as well as the amplitude and frequency of the phase voltage of the AC side filter capacitor of the grid-side inverter of the offshore wind turbine.

[0009] 3) Based on the small-signal dynamic equations of the power level of the offshore rectifier station and the small-signal dynamic equations of the power level of the offshore wind turbine, establish the small-signal model of the power level of the offshore wind field, obtain the open-loop transfer function of the offshore wind field, and obtain the closed-loop transfer function matrix of the offshore wind field according to the open-loop transfer function.

[0010] 4) Obtain the relative gain matrix of the offshore wind field based on the closed-loop transfer function matrix, and obtain the typical value of the relative gain according to the relative gain matrix;

[0011] 5) The relative gain typical value is used to characterize the degree of power coupling between active and reactive power in offshore wind farms;

[0012] Preset upper and lower limit thresholds for typical relative gain values, calculate typical relative gain values ​​for different control pairings and their control parameters. When the typical relative gain value is between the upper and lower limit thresholds, the coupling degree meets the requirements, and the control pairing and its control parameters are reasonable; otherwise, the coupling degree does not meet the requirements, and the control pairing and its control parameters are unreasonable.

[0013] Secondly, this invention discloses a system for analyzing the power coupling characteristics of offshore wind fields based on a relative gain array, used to implement the aforementioned method for analyzing the power coupling characteristics of offshore wind fields based on a relative gain array.

[0014] Thirdly, the present invention discloses an electronic device, including a processor and a memory, wherein the memory stores machine-executable instructions that can be executed by the processor, and the processor executes the machine-executable instructions to implement the above-described method for analyzing the power coupling characteristics of offshore wind fields based on a relative gain array.

[0015] Fourthly, the present invention discloses a machine-readable storage medium storing machine-executable instructions, which, when called and executed by a processor, are used to implement the above-mentioned method for analyzing the power coupling characteristics of offshore wind fields based on a relative gain array.

[0016] Based on the above technical solution, the present invention has the following beneficial technical effects:

[0017] 1) Based on the relative gain method, this invention can quantitatively and quickly characterize the power coupling degree between offshore wind farm equipment, overcoming the shortcomings of previous analysis methods in this scenario that cannot guarantee the effectiveness of the controller when actual operating conditions change, and has the advantage of being able to intuitively show the power coupling characteristics of the system.

[0018] 2) This invention is not limited to the control structure and control pairing of a specific wind turbine grid-side converter. Based on the small-signal model of the power level of offshore wind farms, it can realize the applicability verification of control strategies under various scenarios and equipment interconnection modes, and has the advantage of strong versatility.

[0019] 3) This invention visualizes the interaction mechanism of various equipment connected to the common coupling point at sea, which facilitates the understanding of the influence law of controller parameters, thereby guiding the design of the controller structure and parameters of the offshore wind turbine grid-side converter, and has the advantage of strong practicality. Attached Figure Description

[0020] Figure 1 This is a flowchart of a method for analyzing the power coupling characteristics of offshore wind fields based on a relative gain array, as proposed in this invention.

[0021] Figure 2 This is the equivalent topology of the offshore wind energy transmission system via uncontrolled rectified DC transmission in this embodiment of the invention;

[0022] Figure 3 This is a schematic diagram of the equivalent circuit and control structure of the offshore wind turbine grid-side inverter in an embodiment of the present invention;

[0023] Figure 4 When the proportional coefficient of the active power controller changes in an embodiment of the present invention, λ k11 The Bird diagram;

[0024] Figure 5 When the integral coefficient of the active power controller changes in an embodiment of the present invention, λ k11 The Bird diagram;

[0025] Figure 6 When the droop coefficient of the reactive power controller changes in an embodiment of the present invention, λ k11 The Bird diagram;

[0026] Figure 7 This is an active power response diagram when the proportional coefficient of the active power controller changes in an embodiment of the present invention;

[0027] Figure 8 This is a reactive power response diagram when the proportional coefficient of the active power controller changes in an embodiment of the present invention;

[0028] Figure 9 This is an active power response diagram when the integral coefficient of the active power controller changes in an embodiment of the present invention;

[0029] Figure 10 This is a reactive power response diagram when the integral coefficient of the active power controller changes in an embodiment of the present invention;

[0030] Figure 11 This is a diagram showing the output frequency response when the droop coefficient of the reactive power controller changes in an embodiment of the present invention. Detailed Implementation

[0031] The present invention will be further described and illustrated below with reference to specific embodiments. The embodiments described are merely examples of the content of this disclosure and do not limit the scope of the invention. The technical features of each embodiment in the present invention can be combined accordingly, provided that there is no mutual conflict.

[0032] To explain the invention in more detail, the following example uses a scenario where an offshore wind farm is transmitted via uncontrolled rectified DC power. Figure 1 The process shown Figure 2 The equivalent topology of the offshore wind farm transmitted via an uncontrolled rectified DC power system is shown in the figure. The invention will be further described in detail with reference to the accompanying drawings and embodiments.

[0033] 1) Small-signal dynamic equations of the power stage of the offshore rectifier station: The amplitude and frequency of the phase voltage on the AC side of the offshore rectifier station are used as input vectors, and the active power and reactive power absorbed by the offshore rectifier station are used as output vectors. The small-signal dynamic equations of the power stage of the offshore rectifier station in the complex frequency domain are established by using the small-signal analysis method.

[0034] The offshore wind power transmission equipment (offshore rectifier station) is an uncontrolled rectifier station, and its absorbed active and reactive power are:

[0035]

[0036] Among them, P r Q r The active and reactive power absorbed by the offshore rectifier station (specifically referring to an uncontrolled rectifier station); V r I represents the phase voltage amplitude on the AC side of the offshore rectifier station (specifically referring to an uncontrolled rectifier station); r This refers to the effective value of the phase current on the AC side of the offshore rectifier station (specifically, the uncontrolled rectifier station). This refers to the phase shift between the phase voltage and phase current vector on the AC side of an offshore rectifier station (specifically, an uncontrolled rectifier station).

[0037] Uncontrolled rectifiers satisfy the steady-state equation at the static operating point:

[0038]

[0039] Where μ is the commutation overlap angle; ω rL is the frequency of the phase voltage on the AC side of the offshore rectifier station (specifically referring to an uncontrolled rectifier station); dr The equivalent inductance on the AC side of an offshore rectifier station (specifically referring to an uncontrolled rectifier station); I dc This refers to the phase current on the DC side of the offshore rectifier station (specifically, the uncontrolled rectifier station).

[0040] Using Thevenin's theorem, the high-voltage DC submarine cable is equivalent to a series impedance:

[0041]

[0042] Among them, Z dc For equivalent series impedance; L sm R is the smoothing reactance on the DC side of the offshore rectifier station (specifically referring to an uncontrolled rectifier station); dc1 R dc2 L dc1 L dc2 and C dc The resistance, inductance, and capacitance parameters are used to construct the T-type equivalent circuit of the high-voltage DC submarine cable; s is the Laplace operator.

[0043] By simulating and linearizing the above equations, we obtain the small-signal dynamic equations for the power stage of the offshore rectifier station:

[0044]

[0045] Wherein, ΔP r Small-signal disturbances to active power absorbed by the offshore rectifier station; ΔQ r Small-signal disturbance of reactive power absorbed by the offshore rectifier station; ΔV r Δω is the small-signal disturbance of the phase voltage amplitude on the AC side of the offshore rectifier station. r T represents the small-signal disturbance of the phase voltage frequency on the AC side of the offshore rectifier station. rPV (s), T rPω (s), T rQV (s) and T rQω (s) is the transfer function of the offshore rectifier station in the complex frequency domain; where,

[0046]

[0047] Where, a subscript plus 0 indicates the value of the corresponding variable at the static working point; t is an intermediate quantity used to make the expression more concise; I r0 This refers to the effective value of the phase current on the AC side of the uncontrolled rectifier station at the static operating point. This refers to the phase shift between the phase voltage and phase current vectors on the AC side of the uncontrolled rectifier at the quiescent operating point; V r0 ω represents the amplitude of the phase voltage on the AC side of the uncontrolled rectifier at the quiescent operating point.r0 To avoid controlling the frequency of the phase voltage on the AC side of the rectifier station at the static operating point.

[0048] 2) Establish the small-signal equations of the power stage of the offshore wind turbine: Based on the preset control pairing and control parameters, the active power and reactive power output of the offshore wind turbine are used as input vectors, and the voltage amplitude and frequency of the AC side filter capacitor of the grid-side inverter of the offshore wind turbine are used as output vectors. The small-signal dynamic equations of the power stage of the offshore wind turbine in the complex frequency domain are established by using the small-signal analysis method.

[0049] Figure 3 This is a schematic diagram of the equivalent circuit and control structure of the grid-side inverter for an offshore wind turbine. It adopts grid-based control, and the power loop uses active-voltage and reactive-frequency control pairing. Figure 3 Based on the control structure, the power stage equations of the offshore wind turbine are obtained:

[0050]

[0051] Among them, P i The active power output of the offshore wind turbine; k Pp k is the active power loop proportional controller coefficient. Pi For active loop integral controller coefficients; v n This is the rated voltage value; v Cdref Let v be the d-axis reference voltage of the voltage loop. Since the response speed of the power loop is significantly lower than that of the voltage loop and current loop, when using an equal-amplitude coordinate transformation, the d-axis reference voltage of the voltage loop can be assumed to be equal to the actual voltage amplitude, i.e., v Cdref =V i V i Q represents the amplitude of the phase voltage of the AC side filter capacitor of the grid-side inverter for offshore wind turbines. i The reactive power output of the offshore wind turbine; k Q ω is the reactive power loop droop controller coefficient; n This is the rated frequency value; ω i This refers to the frequency of the phase voltage of the AC side filter capacitor of the grid-side inverter for offshore wind turbines (specifically, the frequency value of the reactive power loop output).

[0052] After linearization, the small-signal dynamic equations of the power stage of the offshore wind turbine are obtained; that is...

[0053]

[0054] Wherein, ΔP i The small-signal disturbance of the active power output of the offshore wind turbine; ΔQ i The small-signal disturbance of the reactive power output of the offshore wind turbine; ΔV iΔω is the small-signal disturbance of the phase voltage amplitude of the AC-side filter capacitor of the grid-side inverter of the offshore wind turbine. i G represents the small-signal disturbance of the phase voltage frequency of the AC side filter capacitor of the grid-side inverter of the offshore wind turbine; iVP (s), G iωP (s), G iVQ (s) and G iωQ (s) is the transfer function of the power loop controller of the grid-side inverter of an offshore wind turbine in the complex frequency domain.

[0055] The active and reactive power loops of the grid-side inverter for wind turbines are generally decoupled, i.e., active power-voltage and reactive power-frequency control are paired (at this time, G...). iVQ (s)=0, G iωP (s)=0), or active-frequency, reactive-voltage control pairing is adopted (at this time, G iVP (s)=0, G iωQ (s)=0). Since the different control pairings do not affect the calculation steps below, for the sake of simplifying the analysis, we take active-voltage and reactive-frequency control pairings as examples, assuming G iVQ (s)=0, G iωP (s) = 0.

[0056]

[0057] Among them, G ivP (s)=k Pp +k Pi / s, G iωQ (s)=k Q .

[0058] 3) Connect the small-signal dynamic equations of the power level of the offshore wind turbine and the small-signal dynamic equations of the power level of the offshore rectifier station to obtain the small-signal model of the power level of the offshore wind farm, and obtain the open-loop transfer function of the offshore wind farm, specifically:

[0059]

[0060] Among them, K ePF (s), K ePC (s), K eQC (s) and K eQF (s) is the open-loop transfer function of the offshore wind field in the complex frequency domain, and K ePF (s)=G iVP (s)×T rPV (s), K ePC (s)=G iωQ (s)×T rPω (s), K eQC (s)=G iVP (s)×TrQV (s), K eQF (s)=G iωQ (s)×T rQω (s).

[0061] The closed-loop transfer function matrix K of the offshore wind field is then calculated based on the open-loop transfer function. cl :

[0062]

[0063] Among them, K ePF (s)=G iVP (s)×T rPV (s), K ePC (s)=G iωQ (s)×T rPω (s), K eQC (s)=G iVP (s)×T rQV (s), K eQF (s)=G iωQ (s)×T rQω (s); k 11 (s), k 12 (s), k 21 (s) and k 22 (s) is the transfer function in the closed-loop transfer function matrix of the offshore wind field, and

[0064]

[0065]

[0066]

[0067]

[0068] 4) Obtain the relative gain matrix of the offshore wind field based on the closed-loop transfer function matrix, and calculate the typical relative gain value of the dual-input dual-output system.

[0069] The relative gain matrix of the offshore wind field is:

[0070]

[0071] Among them, Λ K λ represents the relative gain matrix of the offshore wind field at frequency n, where n is the crossover frequency of the power loop of the grid-side inverter of the offshore wind turbine; k11 This represents a typical value for relative gain; λ k12 , λ k21 and λ k22 λ is the relative gain value, and λ is the relative gain value. k11 =λk22 , λ k12 =λ k21 =1-λ k11 ,Right now:

[0072]

[0073] Since the relative gain matrix of a dual-input dual-output system sums to 1 in each row and column, it is only necessary to calculate the typical relative gain value λ in the first row and first column. k11 . λ k11 When the frequency is n, The amplitude.

[0074] 5) The relative gain typical value is used to characterize the degree of power coupling between active and reactive power in offshore wind farms;

[0075] Based on the relative gain theory, the upper and lower limits of the typical value of relative gain are determined. The typical values ​​of relative gain under different control pairings and their control parameters are calculated. When the typical value of relative gain is between the upper and lower limits, the coupling degree meets the requirements and the control pairing and its control parameters are reasonable. Conversely, the coupling degree does not meet the requirements and the control pairing and its control parameters are unreasonable.

[0076] ①λ k11 =0: The power coupling is very high, and the current control pairing and control parameters are completely unreasonable;

[0077] ②λ k11 =1: The power coupling is very small, and the current control pairing and control parameters are completely reasonable;

[0078] ③0.7<λ k11 <1.3: The power coupling level is within an acceptable range, and the current control pairing and control parameters are reasonable;

[0079] ④λ k11 <0.7 or λ k11 >1.3: Power coupling is relatively high, and the current control pairing and control parameters are unreasonable. The typical relative gain value λ... k11 By mapping to intervals representing different meanings, the power coupling degree between offshore wind farm equipment can be directly obtained. Since the dynamics of the offshore wind farm power loop are mainly reflected around 10Hz, it is only necessary to calculate the relative gain value λ at 10Hz. k11 .

[0080] Figure 4 When the proportional coefficient of the active power controller changes, λ k11 Bode plot. Changing the scaling factor k Pp Take three gradually decreasing values, k Pp1 =0.05kV / MW, k Pp2 =0.04kV / MW and kPp3 = 0.005kV / MW. The λ corresponding to each proportionality coefficient at 10Hz can be directly observed. k11 The amplitudes are 0.720, 0.687, and 0.672, respectively, tending to decrease in the direction deviating from 1, and K... Pp1 When = 0.05kV / MW, 0.7 < λ k11 <1.3, active power-voltage and reactive power-frequency control pairing and control parameters are reasonable. According to relative gain analysis theory, λ k11 As the amplitude deviates from 1, the power coupling increases. This indicates that a decrease in the active power controller proportional coefficient leads to an increase in power coupling in offshore wind farms. To verify the change in power coupling, k... Pp1 k Pp3 k Pp3 The effects of the three scaling factors were simulated in a simulation experiment. Figure 7 and Figure 8 The figures show the response of active and reactive power when the proportional coefficient of the active power controller changes. It can be seen that as the proportional coefficient decreases, the power response overshoot increases and the dynamic performance of the system deteriorates. The experimental results are consistent with the theory.

[0081] Figure 5 When the integral coefficient of the active power controller changes, λ k11 Bode plot. Changing the integral coefficient k Pi Take three gradually decreasing values, k Pi1 =50kV / (sMW), k Pi2 =10kV / (sMW) and k Pi3 = 5kV / (sMW). The λ corresponding to each integral coefficient at 10Hz can be directly observed. k11 The amplitudes are 0.613, 0.72, and 0.815, respectively, increasing towards 1, and taking k... Pi2 k Pi3 When 0.7 < λ k11 <1.3, active power-voltage and reactive power-frequency control pairing and control parameters are reasonable. According to relative gain analysis theory, λ k11 When the amplitude approaches 1, the power coupling decreases. This indicates that a decrease in the integral coefficient of the active power controller leads to a decrease in the power coupling of the offshore wind farm. Simulation experiments were conducted to investigate the effects of the three integral coefficients mentioned above. Figure 9 and Figure 10 The figures show the response graphs of active and reactive power as the integral coefficient of the active power controller changes. It can be seen that as the integral coefficient decreases, the power response overshoot decreases, and the system's dynamic performance is optimized, verifying the three integral coefficient effects obtained from the theoretical analysis.

[0082] Figure 6 When the droop coefficient of the reactive power controller changes, λ k11Bode plot. Change the droop coefficient to three gradually increasing values, k Q1 =0.00698rad / (sMVAr), k Q2 =0.0349rad / (sMVAr), k Q3 = 0.0698 rad / (sMVAr). The λ corresponding to each droop coefficient at 10 Hz can be directly observed. k11 The amplitudes are 0.692, 0.72, and 0.739, respectively, increasing towards 1, and taking k... Q2 k Q3 When 0.7 < λ k11 <1.3 indicates that the active-voltage and reactive-frequency control pairings and control parameters are reasonable. From this, the effect of the reactive power controller droop coefficient can be derived: as the reactive power droop coefficient increases, the coupling degree decreases. Similarly, simulation experiments were conducted to investigate the effects of the three droop coefficients. Figure 11 The output frequency response of the reactive power controller is shown when the droop coefficient changes. It can be seen that as the droop coefficient increases, the power response overshoot decreases and the dynamic effect of the system is optimized, which verifies the effect law of the three droop coefficients obtained from the theoretical analysis.

[0083] The above analysis results verify the intuitiveness, effectiveness, and practicality of the proposed method for calculating the power coupling degree of offshore wind fields based on relative gain arrays.

[0084] This embodiment also provides a system for analyzing the power coupling characteristics of offshore wind fields based on a relative gain array. This system is used to implement the above embodiments, and details already described will not be repeated. The terms "module," "unit," etc., used below refer to combinations of software and / or hardware that perform a predetermined function. Although the system described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible.

[0085] The present invention provides a system for analyzing the power coupling characteristics of offshore wind fields based on a relative gain array, comprising:

[0086] The equation establishment module is used to establish the small-signal dynamic equations of the power level of the offshore rectifier station in the complex frequency domain based on the amplitude and frequency of the phase voltage on the AC side of the offshore rectifier station and the active and reactive power absorbed by the offshore rectifier station.

[0087] Furthermore, based on preset control pairings and control parameters, the offshore wind turbine is controlled; and based on the active power and reactive power output of the offshore wind turbine under current conditions, as well as the amplitude and frequency of the phase voltage of the AC side filter capacitor of the grid-side inverter of the offshore wind turbine, the small-signal dynamic equation of the power level of the offshore wind turbine is established in the complex frequency domain.

[0088] The calculation module is used to establish a power-level small-signal model of the offshore wind field based on the power-level small-signal dynamic equations of the offshore rectifier station and the offshore wind turbine, obtain the open-loop transfer function of the offshore wind field, and obtain the closed-loop transfer function matrix of the offshore wind field based on the open-loop transfer function; and obtain the relative gain matrix of the offshore wind field based on the closed-loop transfer function of the offshore wind field, and obtain the typical value of the relative gain based on the relative gain matrix.

[0089] The analysis module is used to characterize the degree of active and reactive power coupling of the offshore wind field based on the typical value of the relative gain.

[0090] The upper and lower limits of the typical relative gain are preset, and the typical relative gain values ​​are calculated under different control pairs and their control parameters. When the typical relative gain value is between the upper and lower limits, the coupling degree meets the requirements and the control pair and its control parameters are reasonable; otherwise, the coupling degree does not meet the requirements and the control pair and its control parameters are unreasonable.

[0091] The specific implementation process of the functions and roles of each module in the above system is detailed in the corresponding steps of the above method, and will not be repeated here. For the system embodiment, since it basically corresponds to the method embodiment, relevant parts can be referred to in the description of the method embodiment. The system embodiment described above is merely illustrative; the modules described as separate components may or may not be physically separated, i.e., they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of the present invention according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0092] The system embodiments of the present invention can be applied to any device with data processing capabilities, such as a computer or other similar device. The system embodiments can be implemented in software, hardware, or a combination of both. Taking software implementation as an example, as a logical device, it is formed by the processor of any data processing device loading the corresponding computer program instructions from non-volatile memory into memory for execution.

[0093] This invention also provides an electronic device, including a memory and a processor;

[0094] The memory is used to store computer programs;

[0095] The processor is used to implement the above-described method for analyzing the power coupling characteristics of offshore wind fields based on a relative gain array when executing the computer program.

[0096] This invention also provides a computer-readable storage medium storing a program that, when executed by a processor, implements the above-described method for analyzing the power coupling characteristics of offshore wind fields based on a relative gain array.

[0097] The computer-readable storage medium can be an internal storage unit of any data processing device described in any of the foregoing embodiments, such as a hard disk or memory. The computer-readable storage medium can also be an external storage device of any data processing device, such as a plug-in hard disk, smart media card (SMC), SD card, flash card, etc., equipped on the device. Furthermore, the computer-readable storage medium can include both internal storage units and external storage devices of any data processing device. The computer-readable storage medium is used to store the computer program and other programs and data required by the data processing device, and can also be used to temporarily store data that has been output or will be output.

[0098] Obviously, the embodiments and accompanying drawings described above are merely some examples of this application. Those skilled in the art can apply this application to other similar situations based on these drawings without any creative effort. Furthermore, it is understood that although the work done in this development process may be complex and lengthy, for those skilled in the art, certain design, manufacturing, or production modifications made based on the technical content disclosed in this application are merely conventional technical means and should not be considered as insufficient disclosure of this application. Several modifications and improvements can be made without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A method for analyzing the power coupling characteristics of offshore wind fields based on a relative gain array, characterized in that, Includes the following steps: 1) Based on the amplitude and frequency of the phase voltage on the AC side of the offshore rectifier station and the active and reactive power absorbed by the offshore rectifier station, establish the small-signal dynamic equation of the power stage of the offshore rectifier station in the complex frequency domain. 2) Based on the preset control pairing and control parameters, control the offshore wind turbine; and based on the active power and reactive power output of the offshore wind turbine under the current conditions, as well as the amplitude and frequency of the phase voltage of the AC side filter capacitor of the grid-side inverter of the offshore wind turbine, establish the small-signal dynamic equation of the power stage of the offshore wind turbine in the complex frequency domain. 3) Based on the small-signal dynamic equations of the power level of the offshore rectifier station and the small-signal dynamic equations of the power level of the offshore wind turbine, establish the small-signal model of the power level of the offshore wind field, obtain the open-loop transfer function of the offshore wind field, and obtain the closed-loop transfer function matrix of the offshore wind field according to the open-loop transfer function. 4) Obtain the relative gain matrix of the offshore wind field based on the closed-loop transfer function of the offshore wind field, and obtain the typical value of the relative gain according to the relative gain matrix; 5) The relative gain typical value is used to characterize the degree of power coupling between active and reactive power in offshore wind farms; Preset upper and lower limit thresholds for typical relative gain values, calculate typical relative gain values ​​for different control pairings and their control parameters. When the typical relative gain value is between the upper and lower limit thresholds, the coupling degree meets the requirements and the control pairings and their control parameters are reasonable. Conversely, if the coupling degree does not meet the requirements, the control pairing and its control parameters are unreasonable.

2. The method according to claim 1, characterized in that, Step 1) specifically refers to: The amplitude and frequency of the phase voltage on the AC side of the offshore rectifier station are used as input vectors, and the active and reactive power absorbed by the offshore rectifier station are used as output vectors. The small-signal dynamic equations of the power stage of the offshore rectifier station in the complex frequency domain are established using small-signal analysis, namely: Where, ΔP r Small-signal disturbance of active power absorbed by the offshore rectifier station; ΔQ r Small-signal disturbance of reactive power absorbed by the offshore rectifier station; ΔV r Δω is the small-signal disturbance of the phase voltage amplitude on the AC side of the offshore rectifier station. r T represents the small-signal disturbance of the phase voltage frequency on the AC side of the offshore rectifier station. rPV (s), T rPω (s), T rQV (s) and T rQω (s) is the transfer function of the offshore rectifier station in the complex frequency domain.

3. The method according to claim 2, characterized in that, Step 2) specifically refers to: Using the active and reactive power output of the offshore wind turbine under preset control pairing and control parameters as input vectors, and the amplitude and frequency of the voltage of the AC side filter capacitor of the grid-side inverter of the offshore wind turbine under preset control pairing and control parameters as output vectors, the small-signal dynamic equation of the power level of the offshore wind turbine in the complex frequency domain is established by using the small-signal analysis method. Right now: Where, ΔP i The small-signal disturbance of the active power output of the offshore wind turbine; ΔQ i The small-signal disturbance of the reactive power output of the offshore wind turbine; ΔV i Δω is the small-signal disturbance of the phase voltage amplitude of the AC-side filter capacitor of the grid-side inverter of the offshore wind turbine. i G represents the small-signal disturbance of the phase voltage frequency of the AC side filter capacitor of the grid-side inverter of the offshore wind turbine; iVP (s), G iωP (s), G iVQ (s) and G iωQ (s) is the transfer function of the power loop controller of the grid-side inverter of an offshore wind turbine in the complex frequency domain.

4. The method according to claim 3, characterized in that, In step 3), the establishment of a power-level small-signal model of the offshore wind farm based on the power-level small-signal dynamic equations of the offshore rectifier station and the offshore wind turbine specifically involves: Among them, K ePF (s), K ePC (s), K eQC (s) and K eQF (s) is the open-loop transfer function of the offshore wind field in the complex frequency domain, and K ePF (s)=G iVP (s)×T rPV (s), K ePC (s)=G iωQ (s)×T rPω (s), K eQC (s)=G iVP (s)×T rQV (s), K eQF (s)=G iωQ (s)×T rQω (s).

5. The method according to claim 4, characterized in that, In step 3), obtaining the closed-loop transfer function matrix of the offshore wind field based on the open-loop transfer function specifically involves: Among them, K cl Let k be the closed-loop transfer function matrix of the offshore wind field; 11 (s), k 12 (s), k 21 (s) and k 22 (s) is the transfer function in the closed-loop transfer function matrix of the offshore wind field, and 6. The method according to claim 5, characterized in that, Step 4) specifically involves: Among them, Λ K λ represents the relative gain matrix of the offshore wind field at frequency n, where n is the crossover frequency of the power loop of the grid-side inverter of the offshore wind turbine; k11 This represents a typical value for relative gain, and λ k11 When the frequency is n, The amplitude.

7. A system for analyzing the power coupling characteristics of offshore wind fields based on a relative gain array, characterized in that, include: The equation establishment module is used to establish the small-signal dynamic equations of the power level of the offshore rectifier station in the complex frequency domain based on the amplitude and frequency of the phase voltage on the AC side of the offshore rectifier station and the active and reactive power absorbed by the offshore rectifier station. Furthermore, based on preset control pairings and control parameters, the offshore wind turbine is controlled; and based on the active power and reactive power output of the offshore wind turbine under current conditions, as well as the amplitude and frequency of the phase voltage of the AC side filter capacitor of the grid-side inverter of the offshore wind turbine, the small-signal dynamic equation of the power level of the offshore wind turbine is established in the complex frequency domain. The calculation module is used to establish a power-level small-signal model of the offshore wind field based on the power-level small-signal dynamic equations of the offshore rectifier station and the offshore wind turbine, obtain the open-loop transfer function of the offshore wind field, and obtain the closed-loop transfer function matrix of the offshore wind field based on the open-loop transfer function; and obtain the relative gain matrix of the offshore wind field based on the closed-loop transfer function of the offshore wind field, and obtain the typical value of the relative gain based on the relative gain matrix. The analysis module is used to characterize the degree of active and reactive power coupling of the offshore wind field based on the typical value of the relative gain. Preset upper and lower limit thresholds for typical relative gain values, calculate typical relative gain values ​​for different control pairings and their control parameters. When the typical relative gain value is between the upper and lower limit thresholds, the coupling degree meets the requirements and the control pairings and their control parameters are reasonable. Conversely, if the coupling degree does not meet the requirements, the control pairing and its control parameters are unreasonable.

8. An electronic device, characterized in that, The method includes a processor and a memory, the memory storing machine-executable instructions that can be executed by the processor, the processor executing the machine-executable instructions to implement the method for analyzing the power coupling characteristics of offshore wind fields based on a relative gain array as described in any one of claims 1 to 6.

9. A machine-readable storage medium, characterized in that, The machine-readable storage medium stores machine-executable instructions, which, when called and executed by a processor, are used to implement the method for analyzing the power coupling characteristics of offshore wind fields based on a relative gain array as described in any one of claims 1 to 6.

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