Resonance control method and device for offshore wind power diode rectification sending-out system

Abstract

The invention provides a resonance control method and device for an offshore wind power diode rectification sending-out system. The resonance control method comprises the steps that a wind turbine generator disturbance impedance model and a twelve-pulse-wave uncontrolled rectifier disturbance impedance model are constructed; based on the disturbance impedance model of the wind turbine generator and the disturbance impedance model of the twelve-pulse-wave uncontrolled rectifier, performing interactive resonance analysis on the wind turbine generator and the twelve-pulse-wave uncontrolled rectifier to obtain an interactive stability analysis result; and on the basis of the interaction stability analysis result, control parameters of the offshore wind power diode rectification sending-out system are adjusted. The method solves the problem that in the prior art, the stability of an offshore wind power diode rectification sending-out system is not analyzed, and consequently the stability of a wind power system is poor in a complex offshore environment. According to the method, the key control parameters influencing the target node loop resistance are subjected to optimization control through the disturbance impedance model, so that the risk of interactive oscillation between the wind turbine generators is eliminated, and the operation stability of the offshore wind power diode rectification sending-out system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of offshore wind power, and in particular to a resonance control method and device for an offshore wind power diode rectification and transmission system. Background Art

[0002] Wind energy is an important part of the new energy power generation side. Currently, the exploitable wind power resources mainly include onshore and offshore. Compared with onshore wind power, offshore wind power has the advantages of rich resources, high wind speed, good quality and small impact on the environment. There are two main technical routes for offshore wind power transmission: one is AC transmission technology, which is mainly used in offshore, and the other is flexible direct current transmission technology, which is mainly used in offshore. In offshore transmission technology, the main means used are to set up offshore converter stations.

[0003] The stability analysis of the offshore converter station platform is an auxiliary means to ensure the transportation of offshore wind power. At present, the existing technology mainly includes two aspects: floating stability analysis and bottom stability analysis. The floating stability analysis is mainly based on whether the platform is broken during towing and use, and the different inclination angles. The calculation of the overall stability is divided into small inclination angle stability calculation (initial stability calculation) and large inclination angle stability calculation; the bottom stability analysis mainly includes the calculation and analysis of parameters such as the center of buoyancy, metacentric center, initial metacentric center, metacentric radius and restoring moment. At present, the existing technology for the stability analysis of the offshore converter station platform mainly analyzes the influencing factors such as wind and waves, ocean currents and equipment weight distribution, and lacks consideration of the interactive stability between wind turbines and uncontrolled rectifiers and the interactive stability between wind turbines, resulting in poor stability of the offshore wind power diode rectifier transmission system in a complex offshore environment. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes a resonant control method and device for an offshore wind power diode rectifier transmission system, which takes into account the interactive stability between wind turbines and uncontrolled rectifiers and the interactive stability between wind turbines, and improves the operating stability of the offshore wind power diode rectifier transmission system.

[0005] To achieve the above-mentioned purpose, an embodiment of the present invention provides a resonance control method for an offshore wind power diode rectifier transmission system, comprising: constructing a wind turbine disturbance impedance model based on a topological control structure of the wind turbine; constructing a twelve-pulse uncontrolled rectifier disturbance impedance model based on a preset six-pulse uncontrolled rectifier mathematical model; based on the wind turbine disturbance impedance model and the twelve-pulse uncontrolled rectifier disturbance impedance model, performing an interactive resonance analysis on the wind turbine and the twelve-pulse uncontrolled rectifier to obtain an interactive stability analysis result; and adjusting the control parameters of the offshore wind power diode rectifier transmission system based on the interactive stability analysis result.

[0006] Furthermore, the wind turbine disturbance impedance model is constructed based on the topological control structure of the wind turbine, including: obtaining the topological control structure of the reactive self-synchronous wind turbine; constructing a machine-end passive filter dynamic equation through the AC output modulation voltage and the DC dynamic voltage based on the topological control structure of the reactive self-synchronous wind turbine; based on the machine-end passive filter dynamic equation, dynamically representing the AC output modulation voltage and the DC dynamic voltage through the filter capacitor voltage and the filter inductor current on the AC side, to construct the wind turbine disturbance impedance model.

[0007] Furthermore, based on the dynamic equation of the machine-end passive filter, the AC output modulation voltage and the DC dynamic voltage are dynamically represented by the filter capacitor voltage and the filter inductor current on the AC side, and a disturbance impedance model of the wind turbine is constructed, including: dynamically inputting the current and voltage loop control of the system into the dynamic equation of the machine-end passive filter, and outputting a first dynamic equation; modeling the control dynamics of the wind turbine phase-locked loop to obtain a second dynamic equation; constructing a third dynamic equation based on the first dynamic equation and the second dynamic equation; based on the filter capacitor voltage and the filter inductor current on the AC side, the AC output modulation voltage and the DC dynamic voltage are dynamically represented by the third dynamic equation to obtain a disturbance impedance model of the wind turbine.

[0008] Further, the construction of the disturbance impedance model of the twelve-pulse uncontrolled rectifier based on the preset six-pulse uncontrolled rectifier mathematical model includes: constructing a preset six-pulse uncontrolled rectifier mathematical model based on the AC side dq axis voltage, the DC current, the AC measured dq axis current and the DC voltage; performing relationship mapping on the dq axis impedance of the six-pulse uncontrolled rectifier based on the preset six-pulse uncontrolled rectifier mathematical model to obtain the relationship between the dq axis impedance of the six-pulse uncontrolled rectifier and the preset six-pulse uncontrolled rectifier mathematical model; calculating the coefficient analytical expression of the six-pulse uncontrolled rectifier according to the relationship between the dq axis impedance of the six-pulse uncontrolled rectifier and the preset six-pulse uncontrolled rectifier mathematical model; and deducing the preset six-pulse uncontrolled rectifier mathematical model based on the coefficient analytical expression of the six-pulse uncontrolled rectifier to obtain the disturbance impedance model of the twelve-pulse uncontrolled rectifier.

[0009] Further, the calculating of the coefficient analytical expression of the six-pulse uncontrolled rectifier according to the relationship between the dq axis impedance of the six-pulse uncontrolled rectifier and the preset mathematical model of the six-pulse uncontrolled rectifier includes: obtaining the coefficient of the six-pulse uncontrolled rectifier based on the relationship between the dq axis impedance of the six-pulse uncontrolled rectifier and the preset mathematical model of the six-pulse uncontrolled rectifier; obtaining the current and voltage of the commutation state and the current and voltage of the non-commutation state based on the preset pulse interval; averaging the current and voltage of the commutation state and the current and voltage of the non-commutation state, and averaging the current and voltage of the commutation state and the current and voltage of the non-commutation state through dq separation. The method comprises the steps of: calculating an analytical expression of coefficients of a first six-pulse uncontrolled rectifier; performing park transformation and linearization on the current and voltage in the commutation state and the current and voltage in the non-commutation state, calculating an analytical expression of coefficients of a second six-pulse uncontrolled rectifier and an analytical expression of coefficients of a third six-pulse uncontrolled rectifier through dq components; constructing an analytical expression of coefficients of a six-pulse uncontrolled rectifier based on the analytical expression of coefficients of the first six-pulse uncontrolled rectifier, the analytical expression of coefficients of the second six-pulse uncontrolled rectifier and the analytical expression of coefficients of the third six-pulse uncontrolled rectifier.

[0010] Furthermore, based on the coefficient analytical expression of the six-pulse uncontrolled rectifier, a preset six-pulse uncontrolled rectifier mathematical model is deduced to obtain a twelve-pulse uncontrolled rectifier disturbance impedance model, including: based on the coefficient analytical expression of the six-pulse uncontrolled rectifier, constructing a K matrix of the preset six-pulse uncontrolled rectifier mathematical model; obtaining the number of six-pulse uncontrolled rectifiers for constructing the twelve-pulse uncontrolled rectifier to obtain a deduction coefficient; and multiplying the K matrix of the preset six-pulse uncontrolled rectifier mathematical model by the deduction coefficient to obtain the twelve-pulse uncontrolled rectifier disturbance impedance model.

[0011] Furthermore, based on the wind turbine disturbance impedance model and the twelve-pulse uncontrolled rectifier disturbance impedance model, an interactive resonance analysis is performed on the wind turbine and the twelve-pulse uncontrolled rectifier to obtain an interactive stability analysis result, including: based on a preset first interactive condition, simulating the loop impedance change of each node in the system when the wind turbine output active power changes and the loop impedance change of each node when the offshore wind farm reactive power compensation capacity changes by using the wind turbine disturbance impedance model and the twelve-pulse uncontrolled rectifier disturbance impedance model to obtain a plurality of first simulated interactive stability analysis curve graphs; based on the first plurality of simulated interactive stability analysis curve graphs, an interactive resonance analysis is performed on the wind turbine and the twelve-pulse uncontrolled rectifier to obtain a first interactive stability analysis result of the wind turbine and the twelve-pulse uncontrolled rectifier.

[0012] Furthermore, it also includes: based on a second preset interaction condition, simulating the loop impedance change of each node in the system through the wind turbine disturbance impedance model to obtain a second simulated interactive stability analysis curve chart; based on the second simulated interactive stability analysis curve chart, obtaining a second interactive stability analysis result between wind turbines.

[0013] Furthermore, based on the interactive stability analysis results, control parameters of the offshore wind power diode rectifier transmission system are adjusted, including: based on the first interactive stability analysis results of the wind turbine and the twelve-pulse uncontrolled rectifier and the second interactive stability analysis results between the wind turbines, the node with the smallest loop impedance in the system is obtained, and the node with the smallest loop impedance in the system is set as the target node; based on the target node, the key control parameters that affect the loop resistance of the target node are optimized and controlled to adjust the control parameters of the offshore wind power diode rectifier transmission system.

[0014] An embodiment of the present invention also provides a resonance control device for an offshore wind power diode rectifier transmission system, comprising: a first impedance model construction module, a second impedance model construction module, a stability analysis module, and a system control module; the first impedance model construction module is used to construct a wind turbine disturbance impedance model based on the topological control structure of the wind turbine; the second impedance model construction module is used to construct a twelve-pulse uncontrolled rectifier disturbance impedance model based on a preset six-pulse uncontrolled rectifier mathematical model; the stability analysis module is used to perform an interactive resonance analysis on the wind turbine and the twelve-pulse uncontrolled rectifier based on the wind turbine disturbance impedance model and the twelve-pulse uncontrolled rectifier disturbance impedance model to obtain an interactive stability analysis result; the system control module is used to adjust the control parameters of the offshore wind power diode rectifier transmission system based on the interactive stability analysis result.

[0015] Beneficial effects:

[0016] (1) By constructing a wind turbine disturbance impedance model and a twelve-pulse uncontrolled rectifier disturbance impedance model, a resonance analysis is performed on the interaction stability between the wind turbine and the uncontrolled rectifier, and the interaction stability between wind turbines. The control parameters of the offshore wind power diode rectifier transmission system are adjusted to improve the operating stability of the offshore wind power diode rectifier transmission system.

[0017] (2) By obtaining the topological control structure, control and location of each electrical quantity of the reactive self-synchronous wind turbine, a disturbance impedance model of the wind turbine is constructed. The AC dynamic characteristics of the six-pulse uncontrolled rectifier bridge are used to deduce the disturbance impedance model of the twelve-pulse uncontrolled rectifier. This is used to analyze the interactive stability between the wind turbine and the twelve-pulse uncontrolled rectifier, as well as the interactive stability between wind turbines. Finally, the key control parameters that affect the loop resistance of the target node are optimized to adjust the control parameters of the offshore wind power diode rectifier transmission system to eliminate the risk of interactive oscillation between wind turbines and reduce the interactive instability of the units, so as to improve the operating stability of the offshore wind power diode rectifier transmission system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic flow chart of the steps of a resonance control method for an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention;

[0019] Figure 2 A schematic diagram of the topological structure of a reactive self-synchronous control unit of a resonance control method for an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention;

[0020] Figure 3 A schematic diagram of the topological structure of a twelve-pulse uncontrolled rectifier of a resonance control method for an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention;

[0021] Figure 4 A schematic diagram of a dq impedance model frequency sweep verification of a reactive self-balancing control unit of a resonance control method for an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention;

[0022] Figure 5 A schematic diagram of frequency sweep verification of a wide-band impedance model of a twelve-pulse uncontrolled rectifier of a resonance control method for an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention;

[0023] Figure 6 A curve showing the influence of the change in wind turbine output active power on the interaction stability between the twelve-pulse uncontrolled rectifier and the offshore wind farm in a resonance control method of an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention Figure 1 ;

[0024] Figure 7 A curve showing the influence of the change in wind turbine output active power on the interaction stability between the twelve-pulse uncontrolled rectifier and the offshore wind farm in a resonance control method of an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention Figure 2 ;

[0025] Figure 8A curve showing the influence of the change in wind turbine output active power on the interaction stability between the twelve-pulse uncontrolled rectifier and the offshore wind farm in a resonance control method of an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention Figure 3 ;

[0026] Fig. 9 A curve showing the influence of the change of reactive power compensation capacity of an offshore wind farm on the system stability of a resonance control method of an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention Figure 1 ;

[0027] Fig.10 A curve showing the influence of the change of reactive power compensation capacity of an offshore wind farm on the system stability of a resonance control method of an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention Figure 2 ;

[0028] Fig.11 A curve showing the influence of the change of reactive power compensation capacity of an offshore wind farm on the system stability of a resonance control method of an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention Figure 3 ;

[0029] Fig.12 A schematic diagram of the influence of different unit outputs on system stability in a resonance control method of an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention;

[0030] Fig.13 A schematic diagram of the sensitivity of loop resistance parameters in an oscillation frequency band of a resonance control method for an offshore wind power diode rectification and transmission system provided by a certain embodiment of the present invention;

[0031] Fig.14 A schematic diagram of a control optimization feasible domain of key parameters affecting system stability of a resonance control method for an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention;

[0032] Fig.15 A schematic diagram of changes in system positive and negative sequence loop impedances after optimization of key parameters affecting system stability in a resonance control method for an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention;

[0033] Fig.16 A schematic diagram of the module structure of a resonance control device of an offshore wind power diode rectification and transmission system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example 1

[0036] See also Figure 1 , Figure 1 A schematic flow chart of the steps of a resonance control method for an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention. Figure 1 As shown, the embodiment of the present invention proposes a resonance control method for an offshore wind power diode rectification and transmission system, including steps 101 to 104, each of which is specifically as follows:

[0037] Step 101, constructing a disturbance impedance model of a wind turbine generator set based on a topological control structure of the wind turbine generator set;

[0038] As an example of this embodiment, a topological control structure of a reactive self-synchronous wind turbine is obtained; based on the topological control structure of the reactive self-synchronous wind turbine, a dynamic equation of a machine-side passive filter is constructed through the AC output modulation voltage and the DC dynamic voltage; based on the dynamic equation of the machine-side passive filter, the AC output modulation voltage and the DC dynamic voltage are dynamically represented through the filter capacitor voltage and the filter inductor current on the AC side, and a disturbance impedance model of the wind turbine is constructed. Specifically, the current and voltage loop control dynamics of the system are input to the dynamic equation of the machine-side passive filter, and a first dynamic equation is output; the control dynamics of the phase-locked loop of the wind turbine are modeled to obtain a second dynamic equation; based on the first dynamic equation and the second dynamic equation, a third dynamic equation is constructed; based on the filter capacitor voltage and the filter inductor current on the AC side, the AC output modulation voltage and the DC dynamic voltage are dynamically represented through the third dynamic equation to obtain a disturbance impedance model of the wind turbine.

[0039] A specific possible implementation method, in the embodiment of the present invention, the disturbance impedance model of the wind turbine is explained by the small disturbance impedance model of the wind turbine, which will not be repeated below. The small signal impedance model is widely used in converter-based power system analysis. The FMA frequency domain modal analysis method also relies on the small signal impedance model of the high-proportion power electronic system. For the small signal impedance model of the wind turbine, a 2*2 dimensional dq impedance is used for modeling. First, the topological control structure of the reactive self-synchronous wind turbine is obtained, such as Figure 2 As shown, Figure 2A schematic diagram of the topology of a reactive self-synchronous control unit of a resonance control method for an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention; the figure shows the topology, control and location of each electrical quantity of the reactive self-synchronous control unit. Figure 2 , the dq impedance model of the reactive self-synchronous unit can be defined as follows:

[0040]

[0041] The superscript s represents the electrical stationary coordinate system. The modeling process involves the coordinate transformation of electrical quantities between the control reference coordinate system based on the phase-locked loop and the stationary coordinate system. The subscripts d and q represent the dq axis, respectively. ΔU fd and ΔU fq Refers to the capacitor voltage on the grid-side converter C filter, where ΔI d and ΔI q Represents the current flowing through the L filter. dd , Z dq , Z qd and Z qq This is the dq axis impedance model of the reactive self-balancing unit, where Δ represents a small disturbance of the system.

[0042] According to the topological control structure of reactive self-synchronous wind turbine generator ( Figure 2 ), the dynamic equation of the machine-side passive filter is expressed as:

[0043]

[0044] Among them, L f is the LC filter inductor, U d , U q Represents the dq-axis small disturbance component of the converter output voltage, U dm , U qm represents the output modulation dq axis voltage disturbance of the converter control, where ΔU dc Represents the unit DC side dynamics introduced by direct modulation;

[0045] According to the dynamic equation of the machine-side passive filter, the AC output modulation voltage ΔU dm , ΔU qm and DC dynamic ΔU dc The voltage ΔU across the filter capacitor on the AC side fd , ΔU fq , filter inductor current ΔI d , ΔI q Indicates that the small disturbance impedance model of wind turbine is constructed:

[0046] Specifically, first, considering the current and voltage loop control dynamics of the system, the small signal dynamic equation of the wind turbine (equivalent to the first dynamic equation) can be expressed as:

[0047]

[0048] Wherein, the superscript c represents the reference coordinate system of the control system, H pic is the current loop PI controller, G d is the zero-control delay transfer function of the system, H piac is the PI controller of the AC voltage loop, ΔU fdref is the reference d-axis voltage reference value output by the DC voltage outer loop, ΔI qref It is the q-axis current reference value output by the reactive outer loop;

[0049] Then, the control dynamics of the phase-locked loop of the wind turbine is modeled, and the dynamic equation of the phase-locked loop controlling the wind turbine is obtained as follows:

[0050]

[0051] Where x represents any electrical quantity, H pipll is the PI controller transfer function of the phase-locked loop;

[0052] Transforming the small disturbance of the wind turbine in the reference coordinate system based on the phase-locked loop to the stationary coordinate system of the power system, formula (3) can be further expressed as:

[0053]

[0054] Among them, M1 represents the matrix, C f is the LC filter capacitor;

[0055] Then, considering the ω-Q droop control and reactive power control loop of the wind turbine, I in formula (5) qref It can be written as:

[0056]

[0057] Among them, K ωQ The droop coefficient of ω-Q droop control, H piQ It is a PI controller for reactive power control;

[0058] After that, formula (6) can be further rewritten as:

[0059]

[0060] Then, considering the DC voltage outer loop and direct modulation control of the wind turbine, formula (7) is further rewritten as (the process from formula (4) to formula (8) is equivalent to constructing the second dynamic equation):

[0061]

[0062] Among them, H pidc is the PI controller transfer function of the DC voltage control loop;

[0063] Then, referring to the decoupling effect of the DC bus of the full-power wind turbine on the dynamic characteristics of the machine-grid side converter, the machine-side system is equivalent to a power source and has little effect on the analysis results. Therefore, the machine-side system of the wind turbine is equivalent to a constant power source, and ΔU is obtained through power conservation. dc and AC side ΔU fd , ΔU fq and ΔI d , ΔI q The relationship between (equivalent to constructing the third dynamic equation):

[0064]

[0065] Among them C bus is the DC bus capacitance of the unit, P m is the active power output on the generator side, U dc is the DC bus voltage of the unit;

[0066] Finally, the dq axis impedance model of the generator set is derived by combining the first dynamic equation formula (2), the second dynamic equation formula (8) and the third dynamic equation formula (9):

[0067]

[0068] Among them, Z wt It is the dq impedance model of the reactive self-balancing control unit.

[0069] In the embodiment of the present invention, the impedance of the reactive self-balancing control unit can be swept to verify the dq impedance model of the reactive self-balancing control unit. The verification result is as follows: Figure 4 As shown, Figure 4 A schematic diagram of a dq impedance model frequency sweep verification of a reactive self-balancing control unit of a resonance control method for an offshore wind power diode rectifier transmission system provided in an embodiment of the present invention.

[0070] Step 102, constructing a disturbance impedance model of a twelve-pulse uncontrolled rectifier based on a preset six-pulse uncontrolled rectifier mathematical model;

[0071] As an example of this embodiment, based on the AC side dq axis voltage, the DC current, the AC measured dq axis current and the DC voltage, a preset six-pulse uncontrolled rectifier mathematical model is constructed; based on the preset six-pulse uncontrolled rectifier mathematical model, the dq axis impedance of the six-pulse uncontrolled rectifier is relationship mapped to obtain the relationship between the dq axis impedance of the six-pulse uncontrolled rectifier and the preset six-pulse uncontrolled rectifier mathematical model; according to the relationship between the dq axis impedance of the six-pulse uncontrolled rectifier and the preset six-pulse uncontrolled rectifier mathematical model, the coefficient analytical expression of the six-pulse uncontrolled rectifier is calculated; based on the coefficient analytical expression of the six-pulse uncontrolled rectifier, the preset six-pulse uncontrolled rectifier mathematical model is deduced to obtain the disturbance impedance model of the twelve-pulse uncontrolled rectifier. Specifically, based on the relationship between the dq axis impedance of the six-pulse uncontrolled rectifier and the preset mathematical model of the six-pulse uncontrolled rectifier, the coefficient of the six-pulse uncontrolled rectifier is obtained; based on the preset pulse interval, the current and voltage of the commutation state and the current and voltage of the non-commutation state are obtained; the current and voltage of the commutation state and the current and voltage of the non-commutation state are averaged, and the coefficient analytical expression of the first six-pulse uncontrolled rectifier is calculated through the dq component; the current and voltage of the commutation state and the current and voltage of the non-commutation state are park transformed and linearized, and the coefficient analytical expression of the second six-pulse uncontrolled rectifier and the coefficient analytical expression of the third six-pulse uncontrolled rectifier are calculated through the dq component; based on the coefficient analytical expression of the first six-pulse uncontrolled rectifier, the coefficient analytical expression of the second six-pulse uncontrolled rectifier and the coefficient analytical expression of the third six-pulse uncontrolled rectifier, the coefficient analytical expression of the six-pulse uncontrolled rectifier is constructed. Based on the coefficient analytical expression of the six-pulse uncontrolled rectifier, a K matrix of a preset six-pulse uncontrolled rectifier mathematical model is constructed; the number of six-pulse uncontrolled rectifiers for constructing a twelve-pulse uncontrolled rectifier is obtained to obtain a deduction coefficient; and the K matrix of the preset six-pulse uncontrolled rectifier mathematical model is multiplied by the deduction coefficient to obtain a twelve-pulse uncontrolled rectifier disturbance impedance model.

[0072] A specific possible implementation method is as follows: Figure 3 As shown, Figure 3A schematic diagram of the topological structure of a twelve-pulse uncontrolled rectifier of a resonance control method for an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention; the twelve-pulse uncontrolled rectifier uses four groups of six-pulse uncontrolled rectifier bridges, and the small disturbance impedance model of the twelve-pulse uncontrolled rectifier can be deduced using the six-pulse uncontrolled rectifier bridge. The specific steps of constructing the small disturbance impedance model of the twelve-pulse uncontrolled rectifier are: for a single group of six-pulse uncontrolled rectifiers, define the AC side dq axis voltage Vd / Vq and DC current Idc of the six-pulse uncontrolled rectifier as input variables of the six-pulse uncontrolled rectifier, define the AC side dq axis current Id / Iq and DC voltage of the six-pulse uncontrolled rectifier as output variables of the six-pulse uncontrolled rectifier, and construct a mathematical model of the six-pulse uncontrolled rectifier:

[0073]

[0074] According to the mathematical model of the six-pulse uncontrolled rectifier and combined with its DC side dynamic characteristics, the corresponding relationship between the dq axis impedance of the six-pulse uncontrolled rectifier and the mathematical model of the six-pulse uncontrolled rectifier is obtained:

[0075] Firstly, combined with the dynamic characteristics of the DC side of the six-pulse uncontrolled rectifier, the mathematical model of the six-pulse uncontrolled rectifier is transformed into the form of dq axis impedance:

[0076]

[0077] In the above formula, Y dd , Y dq , Y qd , Y qq is the dq impedance matrix element of the diode rectifier;

[0078] The dynamic characteristics of the DC side of the six-pulse uncontrolled rectifier are as follows:

[0079] ΔV dc =Z dc ΔI dc (13)

[0080] Where Z dc is the DC side impedance of the diode uncontrolled rectifier;

[0081] Then, according to formula (12), the corresponding relationship between the dq axis impedance of the six-pulse uncontrolled rectifier and the mathematical model of the six-pulse uncontrolled rectifier can be obtained:

[0082]

[0083] Next, the recursive relationship between the mathematical model of the six-pulse uncontrolled rectifier and the small disturbance impedance model of the twelve-pulse uncontrolled rectifier will be given.

[0084] According to the corresponding relationship between the dq axis impedance of the six-pulse uncontrolled rectifier and the mathematical model of the six-pulse uncontrolled rectifier, the coefficient analytical expression of the six-pulse uncontrolled rectifier is calculated. The coefficient of the uncontrolled rectifier includes K 11 ~K 13 (equivalent to the coefficient analytical expression of the second six-pulse uncontrolled rectifier), K 21 ~K 23 (equivalent to the coefficient analytical expression of the third six-pulse uncontrolled rectifier) ​​and K 31 ~K 33 (equivalent to the analytical expression of the coefficients of the first six-pulse uncontrolled rectifier).

[0085] Considering the case where the AC side of the six-pulse uncontrolled rectifier is an ideal AC voltage source, within a pulse interval on the DC side, the three-phase AC power equation can be written as two independent equations during commutation and non-commutation, as follows:

[0086]

[0087] In the above formula, the variable superscript c represents the commutation state, n represents the non-commutation state, V a 、V b and V c Represents the three-phase power supply voltage on the AC side of the uncontrolled rectifier, L C Represents the AC leakage inductance of the rectifier transformer, I dc Represents the DC side current of the uncontrolled rectifier;

[0088] The three-phase AC voltage in formula (15) is represented by dq components, and the DC voltage in formula (15) is averaged within a pulse, as shown in the following formula:

[0089]

[0090] In the above formula, V d0 and V q0 is the static operating point of the dq axis voltage on the AC side of the diode uncontrolled rectifier, μ is the commutation angle of the diode uncontrolled rectifier;

[0091] Then we can get K of the six-pulse uncontrolled rectifier 31 , K 32 and K 33 The analytical expression of the coefficient (equivalent to the analytical expression of the coefficient of the first six-pulse uncontrolled rectifier) ​​is:

[0092]

[0093] In the above formula, μ0 is the static operating point of the commutation angle on the AC side of the uncontrolled rectifier, where Δμ / ΔV d , Δμ / ΔV q and Δμ / ΔIdc The expression is as follows:

[0094]

[0095] In the above formula, s is the complex frequency and ω0 is the system fundamental frequency.

[0096] Then continue to derive the AC dynamic characteristics of the six-pulse uncontrolled rectifier.

[0097] The specific steps for calculating the coefficient analytical expressions of K11~K13 (equivalent to the coefficient analytical expression of the second six-pulse uncontrolled rectifier) ​​and K21~K23 (equivalent to the coefficient analytical expression of the third six-pulse uncontrolled rectifier) ​​of the six-pulse uncontrolled rectifier are as follows:

[0098] Still within one pulse cycle of the six-pulse uncontrolled rectifier, write the dq axis current I of the AC side of the six-pulse uncontrolled rectifier d / I q The input variable dq axis voltage V d / V q and DC current I dc Taking the d-axis current as an example, the relationship between the AC current and the DC current of the six-pulse uncontrolled rectifier in a pulse time is given as follows:

[0099]

[0100] In the formula, i a 、i b 、i c is the three-phase current on the AC side of the diode uncontrolled rectifier;

[0101] Then, through Park transformation and linearization, we can get I d The analytical expression of the average value during the commutation phase is as follows:

[0102]

[0103] Where φ is the commutation stage I d The angle corresponding to the waveform, I dc represents the d-axis component of the diode AC current during diode commutation, μ represents the diode uncontrolled commutation angle, I 2d Represents the d-axis component of the AC side phase current during diode commutation, I 2q represents the q-axis component of the AC side phase current during diode commutation,

[0104] In addition, m is an expression represented by a symbol, as follows:

[0105]

[0106] At the same time, the relationship between the AC current and DC current of the six-pulse uncontrolled rectifier in the non-commutation stage is given:

[0107]

[0108] Then, through Park transformation, the analytical expression of the average value of the d-axis component of the AC current during one pulse of the six-pulse uncontrolled rectifier and the end of the diode commutation is given:

[0109]

[0110] According to formula (19) through park transformation, I q The analytical expression of the average value during the commutation phase is:

[0111]

[0112] Where φ is the commutation stage I d The angle corresponding to the waveform, represents the q-axis component of the diode AC current during diode commutation, μ represents the diode uncontrolled commutation angle, I 2d Represents the d-axis component of the AC side phase current during diode commutation, I 2q represents the q-axis component of the AC side phase current during diode commutation. In addition, m1 is an expression represented by a symbol, as follows:

[0113]

[0114] According to formula (22) through park transformation, I q The analytical expression of the average value in the non-commutation stage is as follows:

[0115]

[0116] According to the above steps, the average model is further linearized to obtain the model parameters K11~K13 and K21~K23 of the uncontrolled rectifier, and the expressions are as follows:

[0117]

[0118]

[0119] Based on the above solutions to the coefficient analytical expressions of the first six-pulse uncontrolled rectifier, the second six-pulse uncontrolled rectifier and the third six-pulse uncontrolled rectifier, for the twelve-pulse uncontrolled rectifier, its model is derived from four groups of six-pulse uncontrolled rectifier impedance models. Therefore, for the twelve-pulse uncontrolled rectifier, its AC side output current and DC side output voltage are both B times that of a single six-pulse uncontrolled rectifier, where B is the number of six-pulse uncontrolled rectifiers that make up the twelve-pulse uncontrolled rectifier; for the twelve-pulse rectifier, B=4; multiply the K matrix of the mathematical model of the six-pulse uncontrolled rectifier by B as a whole, and you can get the broadband impedance model of the twelve-pulse uncontrolled rectifier:

[0120]

[0121] The subscript 12 represents twelve-pulse rectification.

[0122] In the embodiment of the present invention, the impedance of the twelve-pulse uncontrolled rectifier is swept to verify the broadband impedance model of the twelve-pulse uncontrolled rectifier. The verification result is as follows: Figure 5 as shown. Figure 5 A schematic diagram of frequency sweep verification of a wide-band impedance model of a twelve-pulse uncontrolled rectifier of a resonance control method for an offshore wind power diode rectifier transmission system provided in one embodiment of the present invention.

[0123] Step 103, based on the disturbance impedance model of the wind turbine generator set and the disturbance impedance model of the twelve-pulse uncontrolled rectifier, perform an interactive resonance analysis on the wind turbine generator set and the twelve-pulse uncontrolled rectifier to obtain an interactive stability analysis result;

[0124] As an example of this embodiment, based on the preset first interaction condition, the wind turbine disturbance impedance model and the twelve-pulse uncontrolled rectifier disturbance impedance model are used to simulate the loop impedance changes of each node in the system when the wind turbine output active power changes and the loop impedance changes of each node when the offshore wind farm reactive power compensation capacity changes, and obtain a number of first simulated interactive stability analysis curves; based on the first several simulated interactive stability analysis curves, the wind turbine and the twelve-pulse uncontrolled rectifier are subjected to interactive resonance analysis to obtain the first interactive stability analysis result of the wind turbine and the twelve-pulse uncontrolled rectifier. Based on the second preset interaction condition, the wind turbine disturbance impedance model is used to simulate the loop impedance changes of each node in the system to obtain a second simulated interactive stability analysis curve; based on the second simulated interactive stability analysis curve, a second interactive stability analysis result between wind turbines is obtained.

[0125] A specific possible implementation method, in the embodiment of the present invention, a stability analysis of an offshore wind turbine with grid-type control is performed through a DRU-HVDC transmission system as an explanation, wherein the offshore wind farm is equivalent to a multi-machine aggregation model. The aggregation simulation parameters of the system are shown in Table 1 below:

[0126] Table 1 Aggregation simulation parameters

[0127]

[0128]

[0129] The rated control parameters of the system are shown in Table 2:

[0130] Table 2 Unit rated control parameters

[0131] type parameter <![CDATA[BW C ]]> 600Hz <![CDATA[DR C ]]> 1 <![CDATA[BW AC ]]> 200Hz <![CDATA[DR AC ]]> 1 <![CDATA[BW DC ]]> 50Hz <![CDATA[DR DC ]]> 1 <![CDATA[BW Q ]]> 50Hz <![CDATA[DR Q ]]> 1 <![CDATA[BW PLL ]]> 10Hz <![CDATA[DR PLL ]]> 1 <![CDATA[K fq ]]> 1000

[0132] The multi-machine stability analysis of the system is based on the sum of the loop impedances of each node, and its expression is as follows:

[0133]

[0134] If the real part of the imaginary part of the loop impedance is less than 0 at the zero point, the system is unstable. LIP is the positive sequence loop impedance and Z LIN is the negative sequence loop impedance and.

[0135] The stability analysis of the DRU-HVDC transmission system of offshore wind farms includes two parts, namely: 1. The interactive stability between wind turbines and twelve-pulse uncontrolled rectifiers; 2. The interactive stability between wind turbines; when the output power of all wind turbines is the same (the first interactive condition is preset), the loop impedance changes of each node in the system when the active power output of the wind turbines changes and the loop impedance changes of each node when the reactive compensation capacity of the offshore wind farm changes are simulated, and the curve graph of the influence of the change of the active power output of the wind turbines on the interactive stability of the twelve-pulse uncontrolled rectifier and the offshore wind farm, and the curve graph of the influence of the change of the reactive compensation capacity of the offshore wind farm on the stability of the system are obtained; according to the curve graph of the influence of the change of the active power output of the wind turbines on the interactive stability of the twelve-pulse uncontrolled rectifier and the offshore wind farm, and the curve graph of the influence of the change of the reactive compensation capacity of the offshore wind farm on the stability of the system, it is analyzed that when the output power of all wind turbines is the same, the offshore wind power diode rectifier transmission system has no high-frequency oscillation risk. See Figure 6 , Figure 7 and Figure 8 , Figure 6A curve showing the influence of the change in wind turbine output active power on the interaction stability between the twelve-pulse uncontrolled rectifier and the offshore wind farm in a resonance control method of an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention Figure 1 ; Figure 6 It is a graph showing the change in active output of random groups of the real part of the loop impedance of nodes 1 and 2; Figure 7 A curve showing the influence of the change in wind turbine output active power on the interaction stability between the twelve-pulse uncontrolled rectifier and the offshore wind farm in a resonance control method of an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention Figure 2 ; Figure 7 It is a graph showing the change in active output of random groups of the real part of the loop impedance of nodes 3 and 4; Figure 8 A curve showing the influence of the change in wind turbine output active power on the interaction stability between the twelve-pulse uncontrolled rectifier and the offshore wind farm in a resonance control method of an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention Figure 3 ; Figure 8 It is a curve diagram of the real part of the loop impedance of node 5 and the change of the active output of the random group; by comparison, it can be seen that the real part of the loop impedance of node 5 (PCC point) is the smallest, and it decreases with the decrease of active output, that is, the stability of the system decreases with the decrease of output; see Fig. 9 , Fig.10 and Fig.11 , Fig. 9 A curve showing the influence of the change of reactive power compensation capacity of an offshore wind farm on the system stability of a resonance control method of an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention Figure 1 ; Fig. 9 It is a curve diagram showing the real part of the loop impedance of nodes 1 and 2 changing with the reactive compensation capacity of the offshore wind farm; Fig.10 A curve showing the influence of the change of reactive power compensation capacity of an offshore wind farm on the system stability of a resonance control method of an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention Figure 2 ; Fig.10 It is a curve diagram showing the real part of the loop impedance of nodes 3 and 4 changing with the reactive compensation capacity of the offshore wind farm; Fig.11 A curve showing the influence of the change of reactive power compensation capacity of an offshore wind farm on the system stability of a resonance control method of an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention Figure 3 ; Fig.11It is a curve of the real part of the loop impedance of node 5 and the change of the reactive compensation capacity of the offshore wind farm. By comparison, it can be seen that the real part of the loop impedance of node 5 (PCC point) is the smallest, but it is basically not affected by the change of reactive compensation of the system; therefore, on the basis of the consistent output of each wind turbine, the stability of the system mainly depends on the interaction between the unit and the DRU, because the PCC point has the smallest loop resistance under this condition. And the system has no high-frequency oscillation risk, because the resistance in the high-frequency band is greater than 0.

[0136] When the output power of all wind turbines is different (the second interaction condition is preset), the loop impedance change of each node in the system is simulated to obtain a curve chart showing the influence of different turbine output on system stability. According to the curve chart showing the influence of different turbine output on system stability, it is analyzed that when the output power of all wind turbines is different, there is a risk of instability in the offshore wind power diode rectifier transmission system. Fig.12 , Fig.12 A schematic diagram of the influence of different unit outputs on system stability in a resonance control method of an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention; Fig.12 (a) is a graph showing the change of the positive sequence loop impedance of each node in the system with the random group output. Fig.12 (b) is a graph showing the change of the negative sequence loop impedance of each node of the system with the random group output. By comparison, it can be seen that the outputs of nodes 1-4 are 1p.u., 0.5pu, 0.25pu and 0p.u. respectively. Therefore, the loop impedance of node 4 (unloaded unit) is the smallest, and there is an unstable resonance point of 96.7Hz. Therefore, for the offshore wind power transmission system based on the grid control unit, the main instability risk is the unit interaction instability.

[0137] Step 104: based on the interactive stability analysis result, adjust the control parameters of the offshore wind power diode rectification and transmission system.

[0138] As an example of this embodiment, based on the first interactive stability analysis result of the wind turbine and the twelve-pulse uncontrolled rectifier and the second interactive stability analysis result between the wind turbines, the node with the smallest loop impedance in the system is obtained, and the node with the smallest loop impedance in the system is set as the target node; based on the target node, the key control parameters affecting the loop resistance of the target node are optimized and controlled to adjust the control parameters of the offshore wind power diode rectifier transmission system.

[0139] A specific implementation method is to obtain the node with the smallest loop impedance in the system according to the curve diagram of the influence of different unit outputs on system stability, and the node with the smallest loop impedance is called the target node; the key control parameters affecting the loop resistance of the target node are optimized and controlled so that the real parts of the positive and negative sequence loop impedances of the node are both greater than 0 to eliminate the risk of interactive oscillation between wind turbines. The key control parameters affecting the loop resistance of the target node include the DC voltage loop bandwidth and the AC voltage loop damping; in order to enhance the interactive stability of the system units, the key control parameters affecting the loop resistance of node 4 in the oscillation frequency band are first analyzed, such as Fig.13 As shown, Fig.13 A schematic diagram of the sensitivity of loop resistance parameters in the oscillation frequency band of a resonance control method for an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention; it is found that the DC voltage loop bandwidth and the AC voltage loop damping are key parameters affecting the stability of the system. By optimizing these two key parameters affecting the stability of the system, the real parts of the positive and negative sequence loop impedances of the no-load node are both greater than 0, eliminating the risk of mutual oscillation between units, such as Fig.14 , 15 shown. Fig.14 A schematic diagram of a control optimization feasible domain of key parameters affecting system stability of a resonance control method for an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention; Fig.15 A schematic diagram of changes in system positive and negative sequence loop impedances after optimization of key parameters affecting system stability in a resonance control method for an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention;

[0140] A resonance control method for an offshore wind power diode rectifier transmission system proposed in an embodiment of the present invention constructs a wind turbine disturbance impedance model and a twelve-pulse uncontrolled rectifier disturbance impedance model, resonates the interaction stability between the wind turbine and the uncontrolled rectifier and the interaction stability between the wind turbines, adjusts the control parameters of the offshore wind power diode rectifier transmission system, and improves the operation stability of the offshore wind power diode rectifier transmission system; constructs a wind turbine disturbance impedance model by acquiring the topological control structure, control and location of each electrical quantity of the reactive self-synchronous wind turbine, and derives a twelve-pulse uncontrolled rectifier disturbance impedance model using the AC dynamic characteristics of a six-pulse uncontrolled rectifier bridge, thereby analyzing the interaction stability between the wind turbine and the twelve-pulse uncontrolled rectifier and the interaction stability between the wind turbines; finally, optimizes and controls the key control parameters that affect the target node loop resistance, so as to adjust the control parameters of the offshore wind power diode rectifier transmission system, eliminate the risk of interactive oscillation between wind turbines, and reduce the interactive instability of the units, so as to improve the operation stability of the offshore wind power diode rectifier transmission system.

[0141] Example 2

[0142] See also Fig.16 , Fig.16 A schematic diagram of the module structure of a resonance control device for an offshore wind power diode rectifier transmission system provided by an embodiment of the present invention. Fig.16 As shown, the embodiment of the present invention proposes a resonance control device for an offshore wind power diode rectifier transmission system, comprising: a first impedance model construction module 1601, a second impedance model construction module 1602, a stability analysis module 1603, and a system control module 1604; the first impedance model construction module 1601 is used to construct a wind turbine disturbance impedance model based on a topological control structure of the wind turbine; the second impedance model construction module 1602 is used to construct a twelve-pulse uncontrolled rectifier disturbance impedance model based on a preset six-pulse uncontrolled rectifier mathematical model; the stability analysis module 1603 is used to perform an interactive resonance analysis on the wind turbine and the twelve-pulse uncontrolled rectifier based on the wind turbine disturbance impedance model and the twelve-pulse uncontrolled rectifier disturbance impedance model to obtain an interactive stability analysis result; the system control module 1604 is used to adjust the control parameters of the offshore wind power diode rectifier transmission system based on the interactive stability analysis result.

[0143] A resonant control device for an offshore wind power diode rectifier transmission system proposed in an embodiment of the present invention constructs a disturbance impedance model of the wind turbine by acquiring the topological control structure, control and location of each electrical quantity of a reactive self-synchronous wind turbine. The AC dynamic characteristics of a six-pulse uncontrolled rectifier bridge are used to deduce a disturbance impedance model of a twelve-pulse uncontrolled rectifier. The interactive stability between the wind turbine and the twelve-pulse uncontrolled rectifier, as well as the interactive stability between wind turbines are analyzed. Finally, key control parameters affecting the loop resistance of a target node are optimized and controlled to adjust the control parameters of the offshore wind power diode rectifier transmission system to eliminate the risk of interactive oscillation between wind turbines and reduce the interactive instability of the wind turbines, so as to improve the operating stability of the offshore wind power diode rectifier transmission system.

[0144] The above is only a preferred embodiment of the present invention. It should be noted that for ordinary technicians in the technical field, several improvements and variations can be made without departing from the technical principles of the present invention, and these improvements and variations should also be regarded as the protection scope of the present invention. In the description of this specification, the description of the reference terms "one embodiment", "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 application. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, in the absence of mutual contradiction, the technical personnel in this field can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

Claims

1. A resonance control method for an offshore wind power diode rectifier transmission system, characterized in that: include: Based on the topological control structure of wind turbines, a disturbance impedance model of wind turbines is constructed; Based on the preset six-pulse uncontrolled rectifier mathematical model, a twelve-pulse uncontrolled rectifier disturbance impedance model is constructed; Based on the disturbance impedance model of the wind turbine generator set and the disturbance impedance model of the twelve-pulse uncontrolled rectifier, an interactive resonance analysis is performed on the wind turbine generator set and the twelve-pulse uncontrolled rectifier to obtain an interactive stability analysis result; Based on the interactive stability analysis results, control parameters of the offshore wind power diode rectification and transmission system are adjusted.

2. A resonance control method for an offshore wind power diode rectifier transmission system as claimed in claim 1, characterized in that: The wind turbine generator system disturbance impedance model is constructed based on the topological control structure of the wind turbine generator system, including: Obtain the topological control structure of reactive self-synchronous wind turbines; Based on the topological control structure of the reactive self-synchronous wind turbine generator set, a dynamic equation of a machine-side passive filter is constructed through the AC output modulation voltage and the DC dynamic voltage; Based on the dynamic equation of the machine-end passive filter, the AC output modulation voltage and the DC dynamic voltage are dynamically represented by the filter capacitor voltage and the filter inductor current on the AC side to construct a disturbance impedance model of the wind turbine.

3. A resonance control method for an offshore wind power diode rectifier transmission system as claimed in claim 2, characterized in that: Based on the dynamic equation of the machine-side passive filter, the AC output modulation voltage and the DC dynamic voltage are dynamically represented by the filter capacitor voltage and the filter inductor current on the AC side to construct a disturbance impedance model of the wind turbine, including: Input the current and voltage loop control dynamics of the system into the dynamic equation of the machine-side passive filter, and output a first dynamic equation; Modeling the control dynamics of the wind turbine phase-locked loop to obtain the second dynamic equation; constructing a third dynamic equation based on the first dynamic equation and the second dynamic equation; Based on the filter capacitor voltage and filter inductor current on the AC side, the AC output modulation voltage and the DC dynamic voltage are dynamically represented by the third dynamic equation to obtain the disturbance impedance model of the wind turbine.

4. A resonance control method for an offshore wind power diode rectifier transmission system as claimed in claim 1, characterized in that: The method of constructing a disturbance impedance model of a twelve-pulse uncontrolled rectifier based on a preset six-pulse uncontrolled rectifier mathematical model includes: Based on the AC side dq axis voltage, DC current, AC measured dq axis current and DC voltage, a preset six-pulse uncontrolled rectifier mathematical model is constructed; Based on the preset six-pulse uncontrolled rectifier mathematical model, the dq axis impedance of the six-pulse uncontrolled rectifier is mapped to obtain the relationship between the dq axis impedance of the six-pulse uncontrolled rectifier and the preset six-pulse uncontrolled rectifier mathematical model; According to the relationship between the dq axis impedance of the six-pulse uncontrolled rectifier and the preset mathematical model of the six-pulse uncontrolled rectifier, the coefficient analytical expression of the six-pulse uncontrolled rectifier is calculated; Based on the coefficient analytical expression of the six-pulse uncontrolled rectifier, the preset six-pulse uncontrolled rectifier mathematical model is deduced to obtain the disturbance impedance model of the twelve-pulse uncontrolled rectifier.

5. A resonance control method for an offshore wind power diode rectifier transmission system as claimed in claim 4, characterized in that: The calculation of the coefficient analytical expression of the six-pulse uncontrolled rectifier according to the relationship between the dq axis impedance of the six-pulse uncontrolled rectifier and the preset six-pulse uncontrolled rectifier mathematical model includes: Based on the relationship between the dq axis impedance of the six-pulse uncontrolled rectifier and the preset mathematical model of the six-pulse uncontrolled rectifier, the coefficient of the six-pulse uncontrolled rectifier is obtained; Based on the preset pulse wave interval, the current and voltage in the commutation state and the current and voltage in the non-commutation state are obtained; Averaging the current and voltage in the commutation state and the current and voltage in the non-commutation state, and calculating the coefficient analytical expression of the first six-pulse uncontrolled rectifier through dq components; Performing park transformation and linearization on the current and voltage in the commutation state and the current and voltage in the non-commutation state, and calculating the coefficient analytical expression of the second six-pulse uncontrolled rectifier and the coefficient analytical expression of the third six-pulse uncontrolled rectifier through dq components; Based on the coefficient analytical expression of the first six-pulse uncontrolled rectifier, the coefficient analytical expression of the second six-pulse uncontrolled rectifier and the coefficient analytical expression of the third six-pulse uncontrolled rectifier, the coefficient analytical expression of the six-pulse uncontrolled rectifier is constructed.

6. A resonance control method for an offshore wind power diode rectifier transmission system as claimed in claim 5, characterized in that: Based on the coefficient analytical expression of the six-pulse uncontrolled rectifier, the preset six-pulse uncontrolled rectifier mathematical model is deduced to obtain the disturbance impedance model of the twelve-pulse uncontrolled rectifier, including: Based on the coefficient analytical expression of the six-pulse uncontrolled rectifier, a K matrix of a preset six-pulse uncontrolled rectifier mathematical model is constructed; Obtain the number of six-pulse uncontrolled rectifiers for constructing a twelve-pulse uncontrolled rectifier, and obtain a derivation coefficient; The K matrix of the preset six-pulse uncontrolled rectifier mathematical model is multiplied by the deduction coefficient to obtain the disturbance impedance model of the twelve-pulse uncontrolled rectifier.

7. A resonance control method for an offshore wind power diode rectifier transmission system as claimed in claim 1, characterized in that: Based on the wind turbine disturbance impedance model and the twelve-pulse uncontrolled rectifier disturbance impedance model, an interactive resonance analysis is performed on the wind turbine and the twelve-pulse uncontrolled rectifier to obtain interactive stability analysis results, including: Based on the preset first interactive condition, the wind turbine disturbance impedance model and the twelve-pulse uncontrolled rectifier disturbance impedance model are used to simulate the change of loop impedance of each node in the system when the active power output of the wind turbine changes, and the change of loop impedance of each node when the reactive compensation capacity of the offshore wind farm changes, to obtain a plurality of first simulated interactive stability analysis curves; Based on the first plurality of simulated interactive stability analysis curve diagrams, interactive resonance analysis is performed on the wind turbine generator set and the twelve-pulse uncontrolled rectifier to obtain a first interactive stability analysis result of the wind turbine generator set and the twelve-pulse uncontrolled rectifier.

8. A resonance control method for an offshore wind power diode rectifier transmission system as claimed in claim 7, characterized in that: Also includes: Based on the second preset interaction condition, the loop impedance change of each node in the system is simulated by the wind turbine disturbance impedance model to obtain a second simulated interaction stability analysis curve graph; Based on the second simulated interactive stability analysis curve graph, a second interactive stability analysis result between wind turbines is obtained.

9. A resonance control method for an offshore wind power diode rectifier transmission system as claimed in claim 8, characterized in that: Based on the interactive stability analysis results, the control parameters of the offshore wind power diode rectifier transmission system are adjusted, including: Based on the first interactive stability analysis result between the wind turbine generator set and the twelve-pulse uncontrolled rectifier and the second interactive stability analysis result between the wind turbine generator sets, obtaining a node with the smallest loop impedance in the system, and setting the node with the smallest loop impedance in the system as a target node; Based on the target node, key control parameters that affect the loop resistance of the target node are optimized and controlled to adjust the control parameters of the offshore wind power diode rectification and transmission system.

10. A resonance control device for an offshore wind power diode rectifier transmission system, characterized in that: A resonance control method for an offshore wind power diode rectifier transmission system according to any one of claims 1 to 9 is implemented, comprising: A first impedance model construction module, a second impedance model construction module, a stability analysis module, and a system control module; The first impedance model building module is used to build a disturbance impedance model of the wind turbine generator set based on the topological control structure of the wind turbine generator set; The second impedance model building module is used to build a disturbance impedance model of a twelve-pulse uncontrolled rectifier based on a preset six-pulse uncontrolled rectifier mathematical model; The stability analysis module is used to perform an interactive resonance analysis on the wind turbine and the twelve-pulse uncontrolled rectifier based on the wind turbine disturbance impedance model and the twelve-pulse uncontrolled rectifier disturbance impedance model to obtain an interactive stability analysis result; The system control module is used to adjust the control parameters of the offshore wind power diode rectification and transmission system based on the interactive stability analysis result.

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