Control method for suppressing subsynchronous oscillation of doubly-fed fan and related equipment

Abstract

The embodiment of the invention discloses a control method for suppressing subsynchronous oscillation of a doubly-fed fan and related equipment, relates to the technical field of stable control of a power system, and directly estimates subsynchronous frequency based on inherent parameters such as series compensation capacitance reactance, equivalent inductive reactance and power grid synchronous frequency. The influence of the power grid resistance parameter change on the sub-synchronous frequency estimation value is eliminated; quickly locking a spectrum analysis range based on the obtained subsynchronous frequency estimation value; according to the method, the oscillation frequency, namely the subsynchronous resonant frequency, is accurately locked through fast Fourier decomposition of the rotor current in combination with an amplitude comparison strategy in a preset spectral analysis range, and the subsynchronous resonant frequency in a doubly-fed fan rotor side control system is filtered out, so that oscillation suppression is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of stable control of power systems, and in particular to a control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine and related equipment. Background Art

[0002] As global demand for clean energy continues to grow, wind power, as a key component of renewable energy generation, presents a promising future. Wind farms are often located in remote areas, far from load centers. To address power transmission issues, series capacitor compensation technology is widely used in transmission lines to improve transmission capacity and stability. However, this technology also carries the potential risk of subsynchronous oscillations. Once subsynchronous oscillations occur, they can easily disrupt the normal operation of doubly-fed wind turbines. If effective mitigation measures are not implemented, they can cause wind turbine failure, resulting in extremely adverse impacts on the entire wind power transmission system. Summary of the Invention

[0003] In view of this, the present invention provides a control method and related equipment for suppressing subsynchronous oscillation of a doubly-fed wind turbine.

[0004] The specific technical solution of the first embodiment of the present invention is: a control method for suppressing subsynchronous oscillation of a doubly fed wind turbine, the method comprising: obtaining a subsynchronous frequency estimate of the doubly fed wind turbine in a three-phase coordinate system based on the series compensation capacitor reactance of the doubly fed wind turbine, the equivalent inductive reactance of the doubly fed wind turbine and the grid side, and the grid synchronous frequency; based on a stator voltage d-axis oriented vector control method, obtaining a rotor current on the rotor side of the doubly fed wind turbine based on the stator current of the doubly fed wind turbine and a preset relationship between the stator current and the rotor current; performing fast Fourier decomposition on the rotor current to obtain harmonic components of different frequencies of the rotor current in a dq coordinate system; converting a target harmonic component with a frequency of the subsynchronous frequency estimate into a frequency estimate of a subsynchronous resonance component of the rotor current in the dq coordinate system; comparing the amplitudes of various frequency components within a preset spectrum analysis range with the frequency estimate of the subsynchronous resonance component as the center on the spectrum; determining the frequency corresponding to the frequency component with the largest amplitude as the subsynchronous resonance frequency of the doubly fed wind turbine rotor side control system; and filtering out the subsynchronous resonance frequency in the doubly fed wind turbine rotor side control system.

[0005] Preferably, the subsynchronous frequency estimate is obtained using the following formula:

[0006] in, is the subsynchronous frequency estimate, is the series compensation capacitor reactance, is the equivalent inductive reactance of the doubly fed wind turbine and the grid side, is the grid synchronization frequency.

[0007] Preferably, filtering out the subsynchronous resonant frequency in the doubly fed wind turbine rotor side control system includes: designing a notch filter by taking the subsynchronous resonant frequency as the notch angular frequency in the transfer function of the notch filter; and using the notch filter to filter out the subsynchronous resonant component corresponding to the subsynchronous resonant frequency in the doubly fed wind turbine rotor side control system.

[0008] Preferably, the use of the notch filter to filter out the subsynchronous resonance component corresponding to the subsynchronous resonance frequency in the doubly fed wind turbine rotor side control system includes: connecting the notch filter to the current loop of the rotor side converter of the doubly fed wind turbine rotor side control system to filter out the subsynchronous resonance component.

[0009] Preferably, the relationship between the preset stator current and the rotor current is as follows:

[0010] in, is the mutual inductance between the stator and the rotor, is the stator inductance, is the d-axis component of the rotor current, is the d-axis component of the stator current, is the q-axis component of the rotor current, is the q-axis component of the stator current; the d-axis component of the rotor current and the q-axis component constitute the rotor current.

[0011] Preferably, the transfer function of the notch filter is obtained using the following formula:

[0012] in, is the transfer function, is the Laplace operator, is the subsynchronous resonant frequency, is the preset notch factor.

[0013] Preferably, the subsynchronous resonant frequency is obtained using the following formula:

[0014] in, is the subsynchronous resonant frequency, is the subsynchronous frequency estimate, is the grid synchronization frequency.

[0015] The specific technical solution of the second embodiment of the present invention is: a control system for suppressing subsynchronous oscillation of a doubly fed wind turbine, the system comprising: a subsynchronous frequency estimation value acquisition module, a rotor current acquisition module, a decomposition module, a frequency estimation value acquisition module, a comparison module, a subsynchronous resonant frequency acquisition module and a filtering module; the subsynchronous frequency estimation value acquisition module is used to obtain the subsynchronous frequency estimation value of the doubly fed wind turbine in a three-phase coordinate system based on the series compensation capacitor reactance of the doubly fed wind turbine, the equivalent inductive reactance of the doubly fed wind turbine and the grid side and the grid synchronous frequency; the rotor current acquisition module is used to obtain the rotor current of the rotor side of the doubly fed wind turbine based on the stator voltage d-axis oriented vector control method according to the relationship between the stator current and the rotor current of the doubly fed wind turbine and the preset stator current; The decomposition module is used to perform fast Fourier decomposition on the rotor current to obtain harmonic components of different frequencies of the rotor current in the dq coordinate system; the frequency estimation value acquisition module is used to convert the target harmonic component with the frequency of the subsynchronous frequency estimation value into the frequency estimation value of the subsynchronous resonance component of the rotor current in the dq coordinate system; the comparison module is used to compare the amplitudes of each frequency component within a preset spectrum analysis range with the frequency estimation value of the subsynchronous resonance component as the center on the spectrum; the subsynchronous resonance frequency acquisition module is used to determine the frequency corresponding to the frequency component with the largest amplitude as the subsynchronous resonance frequency of the doubly fed wind turbine rotor side control system; the filtering module is used to filter out the subsynchronous resonance frequency in the doubly fed wind turbine rotor side control system.

[0016] The specific technical solution of the third embodiment of the present invention is: a control device for suppressing subsynchronous oscillation of a doubly fed wind turbine, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method described in any one of the first embodiments of the present application.

[0017] The specific technical solution of the fourth embodiment of the present invention is: a computer-readable storage medium storing a computer program, which, when executed by a processor, enables the processor to perform the steps of the method described in any one of the first embodiments of the present application.

[0018] The implementation of the present invention will have the following beneficial effects: The present invention directly estimates the subsynchronous frequency based on inherent parameters such as series compensation capacitor reactance, equivalent inductive reactance and grid synchronous frequency, eliminating the influence of changes in grid resistance parameters on the subsynchronous frequency estimate; based on the subsynchronous frequency estimate obtained above, the spectrum analysis range is quickly locked; through fast Fourier decomposition of the rotor current and combined with an amplitude comparison strategy within a preset spectrum analysis range, the oscillation frequency, i.e., the subsynchronous resonant frequency, is accurately locked, and the subsynchronous resonant frequency in the rotor-side control system of the doubly fed wind turbine is filtered out, thereby achieving oscillation suppression. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] Figure 1 A flow chart of the steps of a control method for suppressing subsynchronous oscillation of a doubly fed wind turbine; Figure 2 This is a structural diagram of a doubly-fed wind turbine connected to the grid via series compensation; Figure 3 is a schematic diagram of the subsynchronous frequency equivalent circuit; Figure 4 This is the rotor side control block diagram of the doubly fed wind turbine; Figure 5 is the Bode plot of the notch filter; Figure 6 The d-axis current loop control block diagram of the doubly fed wind turbine rotor-side converter with the inner current loop connected to a notch filter; Figure 7 The q-axis current loop control block diagram of the doubly fed wind turbine rotor-side converter with the current inner loop connected to a notch filter; Figure 8 Schematic diagram of the control system for suppressing subsynchronous oscillation of a doubly fed wind turbine; Figure 9 A diagram of the internal structure of a computer device; Among them, 201 is a subsynchronous frequency estimation value acquisition module; 202 is a rotor current acquisition module; 203 is a decomposition module; 204 is a frequency estimation value acquisition module; 205 is a comparison module; 206 is a subsynchronous resonant frequency acquisition module; and 207 is a filtering module. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0022] The terms "first," "second," and the like in the specification, claims, and drawings of this application are used to distinguish between different objects, not to describe a particular order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or modules is not limited to the listed steps or modules but may optionally include steps or modules not listed, or may optionally include other steps or modules inherent to the process, method, product, or apparatus.

[0023] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0024] See also Figure 1 , is a flowchart of the steps of a control method for suppressing subsynchronous oscillation of a doubly fed wind turbine in the first embodiment of the present application, thereby suppressing oscillation, the method comprising: Step 101: Based on the series compensation capacitor reactance of the doubly fed wind turbine , equivalent inductive reactance of the doubly fed wind turbine and the grid side Synchronous frequency with the grid Obtain the subsynchronous frequency estimate of the doubly fed wind turbine in the three-phase coordinate system ; Step 102: Based on the stator voltage d-axis oriented vector control method, the rotor side of the doubly fed wind turbine obtains a rotor current according to the stator current of the doubly fed wind turbine and a preset relationship between the stator current and the rotor current; Step 103: Perform fast Fourier decomposition on the rotor current to obtain harmonic components of different frequencies of the rotor current in a dq coordinate system; Step 104: Set the frequency to the secondary synchronization frequency estimate The target harmonic component is converted into the frequency estimation value of the subsynchronous resonant component of the rotor current in the dq coordinate system ; Step 105: Calculate the frequency estimate of the subsynchronous resonance component on the spectrum. As the center, compare the amplitudes of each frequency component within the preset spectrum analysis range; Step 106: Determine the frequency corresponding to the frequency component with the largest amplitude as the subsynchronous resonant frequency of the doubly fed wind turbine rotor-side control system; Step 107: Filter out the subsynchronous resonant frequency in the doubly-fed wind turbine rotor-side control system.

[0025] Specifically, first obtain the series compensation capacitor reactance , equivalent inductive reactance of the doubly fed wind turbine and the grid side Synchronous frequency with the grid , where the series compensation capacitor reactance is The equivalent inductive reactance of the doubly fed wind turbine and the grid side can be obtained by direct measurement. The equivalent inductive reactance can be measured by injecting disturbance signals into the double-fed wind turbine; the grid synchronization frequency The commonly used setting is 50Hz. Based on the reactance of the series compensation capacitor connected to the DFIG, the equivalent inductive reactance between the DFIG and the grid, and the grid synchronous frequency, the subsynchronous frequency estimate of the DFIG in the three-phase coordinate system is calculated, providing key foundational data for subsequent analysis. Operating based on a stator voltage d-axis oriented vector control method, the DFIG rotor-side controller acquires stator current signals in real time. Based on a pre-defined relationship model between stator current and rotor current, established through extensive experimental and theoretical analysis, the required rotor current is accurately calculated, ensuring accurate and timely control. The calculated rotor current is subjected to fast Fourier decomposition. Using a high-performance digital signal processor, the harmonic components of the rotor current at different frequencies in the dq coordinate system are quickly obtained. The target harmonic component with a frequency equivalent to the subsynchronous frequency estimate is carefully selected and converted into a frequency estimate of the subsynchronous resonant component of the rotor current in the dq coordinate system. In the spectrum analysis phase, the amplitudes of the various frequency components are compared within a preset spectrum analysis range, centered around the frequency estimate of the subsynchronous resonant component using professional spectrum analysis software. After careful investigation, the frequency component with the largest amplitude was identified, and its corresponding frequency was determined to be the subsynchronous resonant frequency of the doubly fed wind turbine's rotor-side control system. Based on the identified subsynchronous resonant frequency, an appropriate filter was designed and implemented in the doubly fed wind turbine's rotor-side control system to filter out this subsynchronous resonant frequency, effectively suppressing the subsynchronous resonance phenomenon, ensuring stable and reliable operation of the doubly fed wind turbine and improving the wind farm's power generation efficiency and power quality.

[0026] Specifically, firstly, a simplified equivalent circuit of the subsynchronous frequency of the doubly fed wind turbine is established based on the doubly fed wind turbine connected to the grid through series compensation. The schematic diagram of the doubly fed wind turbine connected to the grid through series compensation is as follows: Figure 2 As shown in the figure, the simplified analysis of the double-fed wind turbine connected to the grid through series compensation system gives the simplified equivalent circuit of subsynchronous frequency, as shown in the figure. Figure 3 As shown, the subsynchronous frequency estimation value of the control system on the rotor side of the doubly fed wind turbine is estimated based on the equivalent circuit .in, Figure 3 Slip The calculation formula is: ,in, is the rotor speed frequency of the doubly fed wind turbine, generally ,so Based on the obtained Lock the FFT spectrum analysis range, perform fast Fourier decomposition on the rotor current in the dq coordinate system, and determine the subsynchronous resonant frequency. Figure 3 middle, is the slip rate at subsynchronous frequency; 、 are the rotor resistance and stator resistance of the doubly fed wind turbine respectively, is the equivalent resistance of the rotor-side converter, 、 are the rotor leakage reactance and stator leakage reactance at subsynchronous frequency, 、 They are the grid-side equivalent resistance, the grid-side reactance at subsynchronous frequency (including line reactance and transformer leakage reactance), is the equivalent impedance at subsynchronous frequency viewed from the grid side.

[0027] Specifically, FFT is based on the discrete Fourier transform (DFT) theory, which converts discrete time signals into discrete frequency signals, thereby extracting the various frequency components in the signal.

[0028] For a discrete signal of length N, its DFT is defined as:

[0029] in, Represents the complex amplitude of the kth frequency component, corresponding to the frequency , is the sampling frequency.

[0030] Fast Fourier transform (FFT) is an efficient algorithm for calculating DFT. Its basic idea is to decompose a DFT of length N into multiple DFTs of smaller lengths, thereby greatly reducing the amount of calculation.

[0031] According to the sampling frequency and number of sampling points N , calculate the frequency axis:

[0032] Calculate the amplitude of each frequency component in the spectrum, usually taking the modulus of the spectrum:

[0033] in, and The spectral components are The real and imaginary parts of .

[0034] When the three-phase rotor current of the doubly fed wind turbine is decomposed by fast Fourier transform, the frequency is Harmonic components When it is converted to the dq coordinate system, the frequency estimation value of the subsynchronous resonance component can be obtained. . With frequency as The component of is taken as the center, the amplitudes of the frequency components near it are compared, and the frequency corresponding to the frequency component with the largest amplitude is determined as the subsynchronous resonant frequency.

[0035] The method in this embodiment directly estimates the subsynchronous frequency based on inherent parameters such as series compensation capacitor reactance, equivalent inductive reactance, and grid synchronous frequency, eliminating the influence of changes in grid resistance parameters on the subsynchronous frequency estimate; based on the subsynchronous frequency estimate obtained above, the spectrum analysis range is quickly locked; through fast Fourier decomposition of the rotor current and combined with an amplitude comparison strategy within a preset spectrum analysis range, the oscillation frequency, i.e., the subsynchronous resonant frequency, is accurately locked, and the subsynchronous resonant frequency in the rotor-side control system of the doubly fed wind turbine is filtered out to suppress oscillation.

[0036] In a specific embodiment, the subsynchronous frequency estimate It is obtained using the following formula:

[0037] in, is the subsynchronous frequency estimate, is the series compensation capacitor reactance, is the equivalent inductive reactance of the doubly fed wind turbine and the grid side, is the grid synchronization frequency. Specifically, the formula is made clear by the series compensation capacitor reactance And the equivalent inductive reactance of the doubly fed wind turbine and the grid side Synchronous frequency with the grid The subsynchronous frequency estimate is calculated using the relationship Compared to some crude estimation methods, this embodiment comprehensively considers the electrical parameters of key components in the system, enabling more precise determination of the subsynchronous frequency, providing accurate basic data for subsequent analysis and treatment of subsynchronous resonance phenomena. For example, in an actual wind farm system, accurate subsynchronous frequency estimation helps accurately identify frequency points that may cause resonance, avoiding misjudgments or missed detections due to frequency estimation errors.

[0038] In a specific embodiment, filtering out the subsynchronous resonant frequency in the doubly fed wind turbine rotor-side control system includes: designing a notch filter using the subsynchronous resonant frequency as the notch angular frequency in the transfer function of the notch filter; and using the notch filter to filter out the subsynchronous resonant component corresponding to the subsynchronous resonant frequency in the doubly fed wind turbine rotor-side control system. Specifically, the determined subsynchronous resonant frequency is used as the notch angular frequency in the notch filter transfer function, so that the notch filter can be accurately designed for this specific frequency. In the doubly fed wind turbine rotor-side control system, the subsynchronous resonant component can have a serious impact on system stability and power quality. Through this precise design, the notch filter can effectively filter out the component corresponding to the subsynchronous resonant frequency, minimizing its adverse effects on the system.

[0039] In a specific embodiment, the use of the notch filter to filter out the subsynchronous resonance component corresponding to the subsynchronous resonance frequency in the doubly fed wind turbine rotor side control system includes: connecting the notch filter to the current loop of the rotor side converter of the doubly fed wind turbine rotor side control system to filter out the subsynchronous resonance component.

[0040] Specifically, based on the rotor-side control strategy, the adaptive notch filter connection position is determined. First, vector control based on the stator voltage d-axis orientation is adopted to obtain the relationship between the doubly fed wind turbine stator output power and the rotor dq-axis current;

[0041] in, and Represent the stator voltage and stator flux vector respectively. is the active power output by the stator, is the d-axis component of the rotor current, is the q-axis component of the rotor current, and Q is the reactive power output by the stator.

[0042] Active power and reactive power can be controlled by controlling the d-axis and q-axis components of the rotor current respectively. The rotor-side converter adopts double closed-loop control, with the outer loop being the power loop and the inner loop being the current loop. The control block diagram is shown in the figure below. Figure 4 shown.

[0043] According to the power outer loop, the reference values ​​of the d-axis and q-axis components of the corresponding rotor current can be obtained. The d-axis and q-axis components of the actual rotor current can be obtained through the current feedback link. The difference between the reference component and the actual component is passed through the PI controller, and the d-axis and q-axis rotor voltage coupling terms are added to obtain the d-axis and q-axis components of the rotor voltage. The actual rotor voltage can then be controlled by the converter to meet the grid operation requirements.

[0044] In a specific embodiment, the relationship between the preset stator current and the rotor current is as follows:

[0045] in, is the mutual inductance between the stator and the rotor, is the stator inductance, is the d-axis component of the rotor current, is the d-axis component of the stator current, is the q-axis component of the rotor current, is the q-axis component of the stator current; the d-axis component of the rotor current and the q-axis component constitute the rotor current.

[0046] In a specific embodiment, the transfer function of the notch filter is obtained using the following formula:

[0047] in, is the transfer function, is the Laplace operator, is the subsynchronous resonant frequency, is the preset notch factor.

[0048] In a specific embodiment, the subsynchronous resonant frequency is obtained using the following formula:

[0049] in, is the subsynchronous resonant frequency, is the subsynchronous frequency estimate, The notch factor of the notch filter can be adjusted to adjust the blocking bandwidth. The Bode diagram of the notch filter after adjusting the blocking bandwidth is as follows: Figure 5 shown.

[0050] like Figure 6 and Figure 7 As shown, the notch filter in the present invention is connected in series with the PI controller of the inner loop of the current control of the doubly fed wind turbine rotor-side converter, which can filter out the subsynchronous frequency component in the current error signal without amplitude attenuation and phase delay for the DC component, thereby effectively suppressing the subsynchronous oscillation of the grid-connected doubly fed wind farm and improving the stability of the grid operation.

[0051] In the specific embodiment, see Figure 8, is a structural diagram of a control system for suppressing subsynchronous oscillation of a doubly fed wind turbine in the second embodiment of the present application, the system comprising: a subsynchronous frequency estimation value acquisition module 201, a rotor current acquisition module 202, a decomposition module 203, a frequency estimation value acquisition module 204, a comparison module 205, a subsynchronous resonant frequency acquisition module 206 and a filtering module 207; the subsynchronous frequency estimation value acquisition module 201 is used to obtain the subsynchronous frequency estimation value of the doubly fed wind turbine in a three-phase coordinate system according to the series compensation capacitor reactance of the doubly fed wind turbine, the equivalent inductive reactance of the doubly fed wind turbine and the grid side, and the grid synchronization frequency; the rotor current acquisition module 202 is used to obtain the subsynchronous frequency estimation value of the doubly fed wind turbine in a three-phase coordinate system based on the stator voltage d-axis orientation vector control method, and the rotor side of the doubly fed wind turbine obtains the stator current of the doubly fed wind turbine according to the relationship between the stator current and the rotor current of the doubly fed wind turbine and the preset stator current. Rotor current; the decomposition module 203 is used to perform fast Fourier decomposition on the rotor current to obtain harmonic components of different frequencies of the rotor current in the dq coordinate system; the frequency estimation value acquisition module 204 is used to convert the target harmonic component with the frequency of the subsynchronous frequency estimation value into the frequency estimation value of the subsynchronous resonance component of the rotor current in the dq coordinate system; the comparison module 205 is used to compare the amplitudes of each frequency component within a preset spectrum analysis range with the frequency estimation value of the subsynchronous resonance component as the center on the spectrum; the subsynchronous resonance frequency acquisition module 206 is used to determine the frequency corresponding to the frequency component with the largest amplitude as the subsynchronous resonance frequency of the doubly fed wind turbine rotor side control system; the filtering module 207 is used to filter out the subsynchronous resonance frequency in the doubly fed wind turbine rotor side control system.

[0052] The system in this embodiment directly estimates the subsynchronous frequency based on inherent parameters such as series compensation capacitor reactance, equivalent inductive reactance, and grid synchronous frequency, eliminating the influence of changes in grid resistance parameters on the subsynchronous frequency estimate; based on the subsynchronous frequency estimate obtained above, the spectrum analysis range is quickly locked; through fast Fourier decomposition of the rotor current and combined with an amplitude comparison strategy within a preset spectrum analysis range, the oscillation frequency, i.e., the subsynchronous resonant frequency, is accurately locked, and the subsynchronous resonant frequency in the rotor-side control system of the doubly fed wind turbine is filtered out to suppress oscillation.

[0053] In a specific embodiment, the third embodiment of the present application provides a control device for suppressing subsynchronous oscillations of a doubly fed wind turbine, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method as described in any one of the first embodiments of the present application. The device in this embodiment directly estimates the subsynchronous frequency based on the inherent parameters such as the series compensation capacitor reactance, the equivalent inductive reactance and the grid synchronous frequency, thereby eliminating the influence of the change in the grid resistance parameter on the subsynchronous frequency estimate; based on the subsynchronous frequency estimate obtained above, the spectrum analysis range is quickly locked; by fast Fourier decomposition of the rotor current, and combining the amplitude comparison strategy within the preset spectrum analysis range, the oscillation frequency, i.e., the subsynchronous resonant frequency, is accurately locked, and the subsynchronous resonant frequency in the rotor side control system of the doubly fed wind turbine is filtered out to suppress oscillations. In a specific embodiment, the fourth embodiment of the present application is a computer-readable storage medium storing a computer program, characterized in that when the computer program is executed by a processor, the processor executes the steps of the method described in any one of the first embodiments of the present application. The storage medium in this embodiment directly estimates the subsynchronous frequency based on the inherent parameters such as the series compensation capacitor reactance, the equivalent inductive reactance and the grid synchronization frequency, eliminating the influence of the change of the grid resistance parameter on the subsynchronous frequency estimate; based on the subsynchronous frequency estimate obtained above, the spectrum analysis range is quickly locked; through the fast Fourier decomposition of the rotor current, and combined with the amplitude comparison strategy within the preset spectrum analysis range, the oscillation frequency, that is, the subsynchronous resonant frequency, is accurately locked, and the subsynchronous resonant frequency in the rotor side control system of the doubly fed wind turbine is filtered out to achieve oscillation suppression. Figure 9 The internal structure of a computer device in one embodiment is shown. The computer device can be a terminal or a server. Figure 9 The computer device includes a processor, a memory, etc. connected via a system bus. The memory includes a non-volatile storage medium and an internal memory. The non-volatile storage medium of the computer device stores an operating system and may also store a computer program. When the computer program is executed by the processor, the processor can implement the method of this embodiment. The internal memory may also store a computer program. When the computer program is executed by the processor, the processor can implement the method of this embodiment. It will be understood by those skilled in the art that Figure 9 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0054] The above embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0055] The above description is merely a preferred embodiment of the present invention and does not constitute any other form of limitation to the present invention. Any person skilled in the art may utilize the technical contents disclosed above to change or modify them into equivalent embodiments with equivalent changes for application in other fields. However, any simple modification, equivalent change, and modification of the above embodiments made in accordance with the technical essence of the present invention without departing from the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine, characterized in that: The method comprises: Obtain an estimated value of the subsynchronous frequency of the doubly fed wind turbine in a three-phase coordinate system according to the series compensation capacitor reactance of the doubly fed wind turbine, the equivalent inductive reactance of the doubly fed wind turbine and the grid side, and the grid synchronous frequency; Based on the stator voltage d-axis oriented vector control method, the rotor side of the doubly fed wind turbine obtains the rotor current according to the stator current of the doubly fed wind turbine and the relationship between the preset stator current and the rotor current; Performing fast Fourier decomposition on the rotor current to obtain harmonic components of different frequencies of the rotor current in a dq coordinate system; Converting a target harmonic component having a frequency of the subsynchronous frequency estimate value into a frequency estimate value of a subsynchronous resonant component of the rotor current in a dq coordinate system; Comparing the amplitudes of the frequency components within a preset spectrum analysis range with the frequency estimate of the subsynchronous resonance component as the center on the spectrum; The frequency corresponding to the frequency component with the largest amplitude is determined as the subsynchronous resonant frequency of the doubly fed wind turbine rotor side control system; The subsynchronous resonant frequency in the doubly-fed wind turbine rotor-side control system is filtered out.

2. The control method for suppressing subsynchronous oscillation of a doubly fed wind turbine according to claim 1, characterized in that: The subsynchronous frequency estimate is obtained using the following formula: in, is the subsynchronous frequency estimate, is the series compensation capacitor reactance, is the equivalent inductive reactance of the doubly fed wind turbine and the grid side, is the grid synchronization frequency.

3. The control method for suppressing subsynchronous oscillation of a doubly fed wind turbine according to claim 1, characterized in that: The filtering out the subsynchronous resonant frequency in the doubly-fed wind turbine rotor-side control system includes: Designing a notch filter by using the subsynchronous resonant frequency as a notch angular frequency in a transfer function of the notch filter; The notch filter is used to filter out the subsynchronous resonance component corresponding to the subsynchronous resonance frequency in the doubly fed wind turbine rotor side control system.

4. The control method for suppressing subsynchronous oscillation of a doubly fed wind turbine according to claim 3, characterized in that: The method of using the notch filter to filter out the subsynchronous resonance component corresponding to the subsynchronous resonance frequency in the doubly fed wind turbine rotor side control system includes: The notch filter is connected to the current loop of the rotor-side converter of the doubly-fed wind turbine rotor-side control system to filter out subsynchronous resonance components.

5. The control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine according to claim 1, characterized in that: The relationship between the preset stator current and the rotor current is as follows: in, is the mutual inductance between the stator and the rotor, is the stator inductance, is the d-axis component of the rotor current, is the d-axis component of the stator current, is the q-axis component of the rotor current, is the q-axis component of the stator current; the d-axis component of the rotor current and the q-axis component constitute the rotor current.

6. The control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine according to claim 3, characterized in that: The transfer function of the notch filter is obtained using the following formula: in, is the transfer function, is the Laplace operator, is the subsynchronous resonant frequency, is the preset notch factor.

7. The control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine according to claim 6, characterized in that: The subsynchronous resonant frequency is obtained using the following formula: in, is the subsynchronous resonant frequency, is the subsynchronous frequency estimate, is the grid synchronization frequency.

8. A control system for suppressing subsynchronous oscillation of a doubly-fed wind turbine, characterized in that: The system includes: a subsynchronous frequency estimation value acquisition module, a rotor current acquisition module, a decomposition module, a frequency estimation value acquisition module, a comparison module, a subsynchronous resonant frequency acquisition module and a filtering module; The sub-synchronous frequency estimation value acquisition module is used to obtain the sub-synchronous frequency estimation value of the doubly fed wind turbine in the three-phase coordinate system according to the series compensation capacitor reactance of the doubly fed wind turbine, the equivalent inductive reactance of the doubly fed wind turbine and the grid side, and the grid synchronous frequency; The rotor current acquisition module is used for a vector control method based on the stator voltage d-axis orientation, and the rotor side of the doubly fed wind turbine obtains the rotor current according to the stator current of the doubly fed wind turbine and a preset relationship between the stator current and the rotor current; The decomposition module is used to perform fast Fourier decomposition on the rotor current to obtain harmonic components of different frequencies of the rotor current in a dq coordinate system; The frequency estimation value acquisition module is used to convert the target harmonic component with a frequency of the subsynchronous frequency estimation value into a frequency estimation value of the subsynchronous resonance component of the rotor current in the dq coordinate system; The comparison module is used to compare the amplitudes of various frequency components within a preset spectrum analysis range with the frequency estimation value of the subsynchronous resonance component as the center on the spectrum; The subsynchronous resonance frequency acquisition module is used to determine the frequency corresponding to the frequency component with the largest amplitude as the subsynchronous resonance frequency of the doubly fed wind turbine rotor side control system; The filtering module is used to filter out the subsynchronous resonant frequency in the doubly-fed wind turbine rotor-side control system.

9. A control device for suppressing subsynchronous oscillation of a doubly-fed wind turbine, comprising a memory and a processor, characterized in that: The memory stores a computer program, and when the computer program is executed by the processor, the processor is caused to perform the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the processor is caused to perform the steps of the method according to any one of claims 1 to 7.

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