Subsynchronous oscillation suppression method of doubly-fed wind turbine generator and related equipment

Abstract

The invention discloses a subsynchronous oscillation suppression method of a doubly-fed wind turbine generator and related equipment, and belongs to the technical field of wind power generation, and the method comprises the steps: obtaining a voltage control signal of the doubly-fed wind turbine generator in a synchronous rotating coordinate system when the doubly-fed wind turbine generator is connected to a power grid through a series compensation capacitor; extracting a signal of the voltage control signal in a specified frequency band range by using a filter, and performing phase shift compensation on the signal extracted by the filter by using a phase shifter with the goal that the doubly-fed wind turbine generator set meets a positive impedance characteristic in the specified frequency band range; and performing Park inverse transformation on the voltage control signal after phase shift compensation, and controlling a three-phase alternating current output by the doubly-fed wind turbine generator by using the voltage control signal after Park inverse transformation. By means of the method, the technical problems that when subsynchronous oscillation suppression is conducted on the doubly-fed wind turbine generator at present, the needed cost is high, modeling is complex, and engineering application is not easy can be solved.

Description

Technical Field

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

[0002] A doubly-fed wind turbine is a power generation device widely used in wind power generation systems. Among them, the doubly-fed wind turbine includes components such as a doubly-fed induction generator (DFIG), a back-to-back converter, and a box-type transformer for the wind turbine. In practical applications, when the three-phase alternating current output by the doubly-fed wind turbine is incorporated into the power grid, series capacitors are usually connected in the transmission line of the doubly-fed wind turbine to improve the transmission capacity of the line. However, this compensation method also brings the risk of subsynchronous oscillation of the doubly-fed wind turbine, thus seriously affecting the safe and stable operation of the doubly-fed wind turbine.

[0003] In the prior art, usually two methods are used to suppress the subsynchronous oscillation generated by the doubly-fed wind turbine. One method is to deploy hardware devices at the grid end to suppress the subsynchronous oscillation. For example, a wide-frequency oscillation detection system, a synchronous condenser, a voltage regulator, etc. are deployed at the grid end. However, the cost of this suppression method is relatively high. Another method is to suppress the subsynchronous oscillation by optimizing the control parameters or adopting the method of adding virtual impedance at the unit end of the doubly-fed wind turbine. However, this method requires establishing a mathematical model to analyze the impedance reshaping characteristics of the doubly-fed wind turbine. Not only is the mathematical modeling process extremely complex, but also when optimizing the control parameters, it is necessary to rely on the time-domain simulation verification results, and the mathematical model lacks the analytical derivation of this process, so that the control parameters of the doubly-fed wind turbine cannot be more accurately quantified and analyzed, and it is not easy to be applied in engineering. Moreover, this method for suppressing subsynchronous oscillation does not consider the influence of factors such as the dynamic characteristics of the phase-locked loop and control delay in the system where the doubly-fed wind turbine is located during the mathematical modeling process, thus resulting in the suppression effect of the subsynchronous oscillation of the doubly-fed wind turbine falling short of expectations. Currently, there is no relatively effective solution to this technical problem. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method, device, equipment and medium for suppressing subsynchronous oscillation of a doubly-fed generator set, so as to solve the technical problems of high cost, complex modeling and not being easy to be applied in engineering when suppressing subsynchronous oscillation of a doubly-fed wind turbine in the prior art. The specific solutions are as follows:

[0005] To solve the above technical problems, the present invention provides a method for suppressing subsynchronous oscillation of a doubly-fed wind turbine, including:

[0006] When the doubly-fed wind turbine is connected to the power grid through a series compensation capacitor, the voltage control signal of the doubly-fed wind turbine in the synchronous rotating coordinate system is obtained to obtain the first voltage control signal;

[0007] A filter is used to extract the signal of the first voltage control signal within a specified frequency band range, and a phase shifter is used to perform phase shift compensation on the signal extracted by the filter with the goal that the doubly-fed wind turbine satisfies the positive impedance characteristic within the specified frequency band range, so as to obtain a second voltage control signal;

[0008] The Park inverse transformation is performed on the second voltage control signal to obtain a third voltage control signal, and the third voltage control signal is used to control the three-phase alternating current output by the doubly-fed wind turbine, so that the three-phase alternating current output by the doubly-fed wind turbine is incorporated into the power grid.

[0009] Preferably, the filter is specifically a second-order band-pass filter.

[0010] Preferably, the step of using a filter to extract the signal of the first voltage control signal within a specified frequency band range, and using a phase shifter to perform phase shift compensation on the signal extracted by the filter with the goal that the doubly-fed wind turbine satisfies the positive impedance characteristic within the specified frequency band range to obtain a second voltage control signal includes:

[0011] The second-order band-pass filter is used to extract the signal of the first voltage control signal within the specified frequency band range, and the phase shifter is used to perform phase shift compensation on the signal extracted by the second-order band-pass filter with the goal that the doubly-fed wind turbine satisfies the positive impedance characteristic within the specified frequency band range to obtain a target signal;

[0012] The target signal and the signal of the first voltage control signal outside the specified frequency band range are added together to obtain the second voltage control signal.

[0013] Preferably, it further includes:

[0014] Obtain the frequency response transfer functions corresponding to the second-order band-pass filter and the phase shifter;

[0015] The expression of the frequency response transfer function is:

[0016] ;

[0017] In the formula, is the frequency response transfer function, is the damping parameter of the second-order band-pass filter, is the characteristic frequency of the second-order band-pass filter, is the damping parameter of the phase shifter, is the Laplacian operator;

[0018] Determine the minimum value of the magnitude of the frequency response transfer function, and aim at the minimum value of the magnitude of the frequency response transfer function being less than a preset threshold, and for the damping parameter of the second-order band-pass filter, the characteristic frequency of the second-order band-pass filter and the damping parameter of the phase shifter

[0019] Preferably, the expression for the minimum value of the magnitude of the frequency response transfer function is:

[0020] .

[0021] Preferably, it further includes:

[0022] Based on the target model, adjust the damping parameter of the second-order band-pass filter, the characteristic frequency of the second-order band-pass filter and the damping parameter of the phase shifter

[0023] to avoid a 180° phase jump in the impedance phase-frequency characteristics of the second-order band-pass filter and the phase shifter;

[0024] .

[0025] Preferably, it further includes:

[0026] Based on the damping parameter of the second-order band-pass filter, the characteristic frequency of the second-order band-pass filter and the damping parameter of the phase shifter

[0027] To solve the above technical problems, the present invention also provides a subsynchronous oscillation suppression device for a doubly-fed wind turbine, including:

[0028] A signal acquisition module, configured to obtain a voltage control signal of the doubly-fed wind turbine in the synchronous rotating coordinate system to obtain a first voltage control signal when the doubly-fed wind turbine is connected to the power grid through a series compensation capacitor;

[0029] A phase-shifting compensation module is used to extract the signal of the first voltage control signal within a specified frequency band range by using a filter, and aiming at the positive impedance characteristic of the doubly-fed wind turbine within the specified frequency band range, a phase shifter is used to perform phase-shifting compensation on the signal extracted by the filter to obtain a second voltage control signal;

[0030] A signal control module is used to perform Park inverse transformation on the second voltage control signal to obtain a third voltage control signal, and use the third voltage control signal to control the three-phase alternating current output by the doubly-fed wind turbine, so that the three-phase alternating current output by the doubly-fed wind turbine is incorporated into the power grid.

[0031] To solve the above technical problems, the present invention also provides a subsynchronous oscillation suppression device for a doubly-fed wind turbine, including:

[0032] A memory for storing a computer program;

[0033] A processor for implementing the steps of a subsynchronous oscillation suppression method for a doubly-fed wind turbine as disclosed above when executing the computer program.

[0034] To solve the above technical problems, the present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of a subsynchronous oscillation suppression method for a doubly-fed wind turbine as disclosed above are implemented.

[0035] Beneficial effects: Compared with the prior art, since the method provided by the present invention only uses a filter and a phase shifter to perform frequency selection and phase shifting on the voltage control signal of the doubly-fed wind turbine in the synchronous rotating coordinate system, and when aiming at the positive impedance characteristic of the doubly-fed wind turbine within the specified frequency band range and using the phase shifter to perform phase-shifting compensation on the signal extracted by the filter, the purpose of adjusting and optimizing the impedance characteristic of the doubly-fed wind turbine within a specific frequency band can be achieved, so that the subsynchronous oscillation generated by the doubly-fed wind turbine can be suppressed. Obviously, since this subsynchronous oscillation suppression method does not require adding hardware devices on the grid side and does not require creating complex mathematical models, it can not only reduce the cost investment required for suppressing subsynchronous oscillation, but also reduce the operation complexity of suppressing subsynchronous oscillation. And, in this method, the control parameters of the filter and the phase shifter can be adjusted and optimized in real time according to actual needs, which is more convenient for engineering applications.

[0036] Correspondingly, a subsynchronous oscillation suppression device, equipment and medium for a doubly-fed wind turbine provided by the present invention also have the above beneficial effects. Description of the Drawings

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings.

[0038] Figure 1 It is a flowchart of a method for suppressing subsynchronous oscillation of a doubly-fed wind turbine provided by an embodiment of the present invention;

[0039] Figure 2 It is a control schematic diagram of adding a frequency-selective phase-shifting link to the machine-side converter when performing grid connection control on a doubly-fed wind turbine;

[0040] Figure 3 It is a control block diagram of the frequency-selective phase-shifting link;

[0041] Figure 4 It is an amplitude-frequency characteristic curve of the frequency input-output response of the frequency-selective phase-shifting link built with the parameters shown in Table 1;

[0042] Figure 5 It is a phase-frequency characteristic curve of the frequency input-output response of the frequency-selective phase-shifting link built with the parameters shown in Table 1;

[0043] Figure 6 It is a result diagram when testing the impedance amplitude-frequency characteristic of a doubly-fed wind turbine using a semi-physical simulation platform;

[0044] Figure 7 It is a result diagram when testing the impedance phase-frequency characteristic of a doubly-fed wind turbine using a semi-physical simulation platform;

[0045] Figure 8 It is a structural diagram of a device for suppressing subsynchronous oscillation of a doubly-fed wind turbine provided by an embodiment of the present invention;

[0046] Figure 9 It is a structural diagram of a device for suppressing subsynchronous oscillation of a doubly-fed wind turbine provided by an embodiment of the present invention. Specific embodiments

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0048] Please refer to Figure 1 ,Figure 1 The flowchart of a method for suppressing subsynchronous oscillation of a doubly-fed wind turbine provided by an embodiment of the present invention. The method includes:

[0049] Step S11: When the doubly-fed wind turbine is connected to the power grid through a series compensation capacitor, obtain the voltage control signal of the doubly-fed wind turbine in the synchronous rotating coordinate system to obtain a first voltage control signal;

[0050] Step S12: Use a filter to extract the signal of the first voltage control signal within a specified frequency band range, and use a phase shifter to perform phase shift compensation on the signal extracted by the filter with the goal of making the doubly-fed wind turbine satisfy the positive impedance characteristic within the specified frequency band range to obtain a second voltage control signal;

[0051] Step S13: Perform an inverse Park transformation on the second voltage control signal to obtain a third voltage control signal, and use the third voltage control signal to control the three-phase alternating current output by the doubly-fed wind turbine so that the three-phase alternating current output by the doubly-fed wind turbine is incorporated into the power grid.

[0052] In this embodiment, in order to suppress the subsynchronous oscillation generated by the doubly-fed wind turbine, first, obtain the voltage control signal of the doubly-fed wind turbine in the synchronous rotating coordinate system to obtain a first voltage control signal. Since the first voltage control signal contains control signals of other frequency bands that are irrelevant to the subsynchronous oscillation frequency band. Therefore, in order to adjust and optimize the impedance characteristic of the doubly-fed wind turbine in a specific frequency band, after obtaining the first voltage control signal, it is necessary to use a filter to extract the signal of the first voltage control signal within a specified frequency band range.

[0053] Specifically, in this embodiment, the double closed-loop control system of the machine-side converter of the doubly-fed wind turbine is used to obtain the voltage control signal of the doubly-fed wind turbine in the synchronous rotating coordinate system. Among them, the double closed-loop control system includes: a power loop, a current loop, and a phase-locked loop. That is, in this embodiment, the power loop, the current loop, and the phase-locked loop are used to obtain the voltage control signal of the doubly-fed wind turbine in the synchronous rotating coordinate system. And, according to the actual application requirements, in this embodiment, the specified frequency band range is set to 0~20Hz.

[0054] When using a filter to extract the signal of the first voltage control signal within a specified frequency band range, with the goal of making the doubly-fed wind turbine satisfy the positive impedance characteristic within the specified frequency band range, use a phase shifter to perform phase shift compensation on the signal extracted by the filter to obtain a second voltage control signal, and perform an inverse Park transformation on the second voltage control signal to obtain a third voltage control signal.

[0055] After obtaining the third voltage control signal, it is equivalent to obtaining the three-phase alternating voltage for regulating the doubly-fed wind turbine generator set. At this time, the third voltage control signal can be used to control the three-phase alternating current output by the doubly-fed wind turbine generator set, so that the three-phase alternating current output by the doubly-fed wind turbine generator set can be safely and stably incorporated into the power grid.

[0056] The sub-synchronous oscillation suppression method provided in this embodiment is equivalent to adding a frequency-selective phase-shifting link composed of a filter and a phase shifter at the current loop output end of the machine-side converter. The filter in the frequency-selective phase-shifting link can extract the voltage control signal of the doubly-fed wind turbine generator set within the specified frequency band range in the synchronous rotating coordinate system, and the phase shifter in the frequency-selective phase-shifting link can perform phase-shifting processing on the voltage control signal of the doubly-fed wind turbine generator set within the specified frequency band range, so as to achieve the purpose of adjusting and optimizing the impedance characteristics of the doubly-fed wind turbine generator set within the specified frequency band range.

[0057] To enable those skilled in the art to more clearly understand the implementation principle of this application, the control strategy of the doubly-fed wind turbine generator set involved in this application is briefly described here. Please refer to Figure 2 , Figure 2 is a control schematic diagram of adding a frequency-selective phase-shifting link to the machine-side converter when performing grid connection control on the doubly-fed wind turbine generator set. When the doubly-fed wind turbine generator set is connected to the power grid through a series capacitor, in order to incorporate the three-phase alternating current generated by the doubly-fed wind turbine generator set into the power grid, first, the double closed-loop control system of the machine-side converter is used to obtain the voltage control signal of the doubly-fed wind turbine generator set in the synchronous rotating coordinate system. Among them, the double closed-loop control system includes a power loop, a current loop, and a phase-locked loop. When the reference active power , reference reactive power , actual active power and actual reactive power of the doubly-fed induction wind turbine generator set pass through the power loop, the reference current and of the machine-side converter in the synchronous rotating coordinate system will be generated. The reference current and of the machine-side converter in the synchronous rotating coordinate system and the actual current and of the machine-side converter in the synchronous rotating coordinate system pass through the current loop, and the reference voltage of the machine-side converter in the synchronous rotating coordinate system will be generated. The reference voltage is the first voltage control signal.

[0058] The reference voltage After being processed by the frequency-selective phase-shifting link, the second voltage control signal will be obtained, and the second voltage control signal After the Park inverse transformation and the processing of the phase-locked loop, a three-phase AC voltage for regulating the doubly-fed wind turbine generator set is generated. The three-phase AC voltage is the third voltage control signal. Through the above closed-loop control process, the purpose of real-time regulation of the three-phase alternating current output by the doubly-fed wind turbine generator set can be achieved. Moreover, the sub-synchronous oscillation of the doubly-fed wind turbine generator set can be avoided.

[0059] Compared with the prior art, since the method provided by the present invention only uses a filter and a phase shifter to perform frequency selection and phase shift processing on the voltage control signal of the doubly-fed wind turbine generator set in the synchronous rotating coordinate system. At the same time, when the positive impedance characteristic of the doubly-fed wind turbine generator set within a specified frequency band range is used as the target, and the phase shifter is used to perform phase shift compensation on the signal extracted by the filter, the purpose of adjusting and optimizing the impedance characteristic of the doubly-fed wind turbine generator set within a specific frequency band can be achieved. In this way, the sub-synchronous oscillation generated by the doubly-fed wind turbine generator set can be suppressed. Obviously, since this sub-synchronous oscillation suppression method does not require adding hardware devices on the grid side and does not require creating complex mathematical models, it can not only reduce the cost investment required for suppressing sub-synchronous oscillation, but also reduce the operation complexity of suppressing sub-synchronous oscillation. Moreover, in this method, the control parameters of the filter and the phase shifter can be adjusted and optimized in real time according to actual needs, which makes it more convenient for engineering applications.

[0060] Based on the above embodiments, this embodiment further explains and optimizes the technical solution. As a preferred implementation manner, the filter is specifically a second-order band-pass filter.

[0061] Since the circuit structure of the second-order band-pass filter is simple and the manufacturing cost is low, and the center frequency of the second-order band-pass filter can be changed by adjusting the parameter values of the capacitor and the inductor, this working performance of the second-order band-pass filter enables it to adapt to different signal processing requirements, which can significantly improve the convenience of the sub-synchronous oscillation method described in this application in practical applications.

[0062] Specifically, the transfer function of the second-order band-pass filter is as follows:

[0063] Formula 1: ;

[0064] In the formula, is the transfer function of the second-order band-pass filter, is the damping parameter of the second-order band-pass filter, is the characteristic frequency of the second-order band-pass filter, is the Laplace operator.

[0065] As a preferred embodiment, the above steps: extracting the signal of the first voltage control signal within a specified frequency band range by using a filter, and taking the positive impedance characteristic of the doubly-fed wind turbine within the specified frequency band range as the target, and using a phase shifter to perform phase shift compensation on the signal extracted by the filter to obtain a second voltage control signal, including:

[0066] Extracting the signal of the first voltage control signal within a specified frequency band range by using a second-order band-pass filter, and taking the positive impedance characteristic of the doubly-fed wind turbine within the specified frequency band range as the target, and using a phase shifter to perform phase shift compensation on the signal extracted by the second-order band-pass filter to obtain a target signal;

[0067] Adding the target signal and the signal of the first voltage control signal outside the specified frequency band range to obtain a second voltage control signal.

[0068] In this embodiment, the transfer function of the phase shifter is:

[0069] Formula 2: ;

[0070] In the formula, is the transfer function of the second-order band-pass filter, is the damping parameter of the phase shifter, is the Laplace operator.

[0071] Combining the second-order band-pass filter and the phase shifter can obtain a frequency-selective phase-shifting link. Please refer to Figure 3 , Figure 3 is the control block diagram of the frequency-selective phase-shifting link. In Figure 3 , 101 represents the second-order band-pass filter, 102 represents the phase shifter, and 103 represents the frequency-selective phase-shifting link. When obtaining the second voltage control signal , first, the second-order band-pass filter 101 is used to extract the signal of the first voltage control signal within the specified frequency band range, and taking the positive impedance characteristic of the doubly-fed wind turbine within the specified frequency band range as the target, the phase shifter 102 is used to perform phase shift compensation on the signal extracted by the second-order band-pass filter 101 to obtain a target signal ; then, the target signal and the signal of the first voltage control signal outside the specified frequency band range are added to obtain the second voltage control signal .

[0072] Obviously, through the technical solution provided by this embodiment, the second voltage control signal can be accurately obtained.

[0073] As a preferred embodiment, the above subsynchronous oscillation suppression method further includes:

[0074] Obtain the frequency response transfer functions corresponding to the second-order band-pass filter and the phase shifter;

[0075] The expression of the frequency response transfer function is:

[0076] ;

[0077] In the formula, is the frequency response transfer function, is the damping parameter of the second-order band-pass filter, is the characteristic frequency of the second-order band-pass filter, is the damping parameter of the phase shifter, is the Laplace operator;

[0078] Determine the minimum value of the amplitude of the frequency response transfer function, and target that the minimum value of the amplitude of the frequency response transfer function is less than a preset threshold, and adjust the damping parameter of the second-order band-pass filter, the characteristic frequency of the second-order band-pass filter, and the damping parameter

[0079] In this application, since the frequency selection and phase shift link composed of the second-order band-pass filter and the phase shifter is added to the output end of the current loop of the machine-side converter of the doubly-fed wind turbine, therefore, the frequency selection and phase shift link will only increase or decrease the phase in the impedance characteristic curve of the doubly-fed wind turbine, and will not affect the overall change trend of the impedance characteristic curve of the doubly-fed wind turbine. Based on this attribute characteristic of the frequency selection and phase shift link, we can roughly infer the change law of the impedance characteristic curve of the doubly-fed wind turbine by analyzing the frequency selection and phase shift link.

[0080] In order to analyze the frequency selection and phase shift link composed of the second-order band-pass filter and the phase shifter, in this embodiment, first, obtain the frequency response transfer functions corresponding to the second-order band-pass filter and the phase shifter.

[0081] Among them, the expression of the frequency response transfer function is:

[0082] Formula 3: ;

[0083] In the formula, is the frequency response transfer function, is the damping parameter of the second-order band-pass filter, is the characteristic frequency of the second-order band-pass filter, is the damping parameter of the phase shifter, is the Laplace operator.

[0084] On the amplitude-frequency characteristic curve of the frequency response transfer function, a frequency selection and phase shift link will have a minimum amplitude value on the right side of the characteristic frequency of the second-order band-pass filter. As increases, the frequency at which the minimum amplitude value appears shifts to the right, and the corresponding value of the minimum decreases. As increases, the frequency at which the minimum amplitude value appears shifts to the left, and the corresponding value of the minimum increases. According to the relevant mathematical model, the angular frequency value corresponding to the minimum amplitude of the transfer function of the frequency selection and phase shift link can be calculated as:

[0085] Formula 4: ;

[0086] At this time, the expression corresponding to the minimum amplitude value is:

[0087] Formula 5: ;

[0088] In practical applications, in order to improve the suppression effect on subsynchronous oscillation, we need to ensure that the amplitude reduction of the frequency selection and phase shift link is relatively gentle and not too much. In this case, it is necessary to adjust the damping parameter of the second-order band-pass filter, the characteristic frequency of the second-order band-pass filter, and the damping parameter of the phase shifter with the goal that the minimum amplitude value of the frequency response transfer function is less than a preset threshold. Among them, the preset threshold is: the threshold set according to human experience to avoid subsynchronous oscillation of the doubly-fed wind turbine.

[0089] As a preferred implementation manner, the above-mentioned subsynchronous oscillation suppression method further includes:

[0090] Based on the target model, adjust the damping parameter of the second-order band-pass filter, the characteristic frequency of the second-order band-pass filter, and the damping parameter of the phase shifter to avoid a 180° phase jump in the impedance phase-frequency characteristics of the second-order band-pass filter and the phase shifter;

[0091] The expression of the target model is:

[0092] Formula 6: .

[0093] On the phase-frequency characteristic curve of the frequency selection and phase shift link, the starting frequency point where the frequency selection and phase shift link generates the phase-frequency adjustment characteristic effect is mainly affected by the characteristic frequency of the second-order band-pass filter and the damping parameter For the influence, the cut-off frequency point of the phase shift-down section will be affected by the combined action of the second-order band-pass filter and the phase shifter. When there is a 180° phase jump in the impedance phase-frequency characteristics of the second-order band-pass filter and the phase shifter, it means that the phase of the frequency-selective phase-shifting link will undergo a sharp reversal at certain frequencies. This will not only cause distortion and uncontrollability of the output signal, but also trigger strong oscillations. To avoid this phenomenon, it is necessary to be based on the target model to adjust the damping parameter of the second-order band-pass filter , the characteristic frequency of the second-order band-pass filter and the damping parameter of the phase shifter, and thereby avoid a 180° phase jump in the impedance phase-frequency characteristics of the second-order band-pass filter and the phase shifter.

[0094] Based on the above parameter design principle of the frequency-selective phase-shifting link, the damping parameter of the second-order band-pass filter , the characteristic frequency of the second-order band-pass filter and the damping parameter of the phase shifter can be adjusted. When the damping parameter of the second-order band-pass filter , the characteristic frequency of the second-order band-pass filter and the damping parameter of the phase shifter are adjusted, if the overall impedance characteristic of the system where the doubly-fed wind turbine is located falls within in the specified frequency band range, it can be determined that the doubly-fed wind turbine satisfies the positive impedance characteristic in the specified frequency band range.

[0095] Obviously, when using this method to suppress the subsynchronous oscillation of the doubly-fed wind turbine, since this method does not require adding hardware devices on the grid side, nor creating complex mathematical models, only by adjusting the set parameters of the second-order band-pass filter and the phase shifter in the frequency-selective phase-shifting link, the purpose of suppressing the subsynchronous oscillation can be achieved. This can not only reduce the cost investment required for suppressing the subsynchronous oscillation, but also reduce the operation complexity of suppressing the subsynchronous oscillation. Moreover, in this method, the control parameters of the second-order band-pass filter and the phase shifter can be adjusted and optimized in real time according to actual needs, which makes it more convenient for engineering applications.

[0096] As a preferred implementation manner, the above subsynchronous oscillation suppression method further includes:

[0097] Based on the damping parameter of the second-order band-pass filter , the characteristic frequency of the second-order band-pass filter and the damping parameter of the phase shifter Build a hardware-in-the-loop simulation platform corresponding to the doubly-fed wind turbine, and use the hardware-in-the-loop simulation platform to test the amplitude-frequency characteristics and phase-frequency characteristics of the doubly-fed wind turbine.

[0098] In this embodiment, in order to verify the effectiveness of the subsynchronous oscillation suppression method described in this application, the damping parameter of the second-order band-pass filter , the characteristic frequency of the second-order band-pass filter and the damping parameter of the phase shifter can also be used to build a hardware-in-the-loop simulation platform corresponding to the doubly-fed wind turbine, and use the hardware-in-the-loop simulation platform to test the amplitude-frequency characteristics and phase-frequency characteristics of the doubly-fed wind turbine.

[0099] Specifically, a real-time digital simulation system control cabinet, a wind power converter control simulation box, a wind turbine main controller, and a power amplifier for data interaction between the simulation model and the wind turbine main controller can be set in the hardware-in-the-loop simulation platform. Among them, the wind power converter control simulation box can control the start and stop of the wind turbine main controller through the upper computer and control the grid connection operation of the doubly-fed wind turbine and the power grid, so as to simulate the actual operating conditions of the doubly-fed wind turbine.

[0100] Here, a system in which a doubly-fed wind turbine in a wind farm is sent out through a series-compensated power grid is used as an example to specifically illustrate the subsynchronous oscillation method described in this application. After oscillation risk assessment and stability analysis, it is required that the phase of the impedance characteristic of the doubly-fed wind turbine satisfies the positive impedance characteristic in the frequency range of 0 to 20 Hz, that is, it is required that the overall impedance characteristic of the system where the doubly-fed wind turbine is located falls within in the frequency range of 0 to 20 Hz. After Park transformation, this frequency band will be converted into a frequency range of 30 to 50 Hz in the synchronous rotating coordinate system. Combining the foregoing mathematical model derivation and calculation, the setting parameters of the second-order band-pass filter and the phase shifter added at the output end of the machine-side converter current loop of the doubly-fed wind turbine are shown in Table 1.

[0101] Table 1

[0102]

[0103] According to Formula 4 and Formula 5, the minimum value of the impedance amplitude-frequency characteristic of the frequency-selective phase-shifting link can be calculated to be -10.0 dB, which appears at , and this parameter meets the requirements of Formula 6, that is, the impedance phase-frequency characteristic of the frequency-selective phase-shifting link will not produce a phenomenon of crossing 180°. Use the parameters shown in Table 1 to build the frequency-selective phase-shifting link in the hardware-in-the-loop simulation platform.

[0104] Please refer to Figure 4 and Figure 5 , Figure 4The figure is the amplitude-frequency characteristic curve of the frequency input and output response of the frequency selection and phase shift link built with the parameters shown in Table 1. Figure 5 The figure is the phase-frequency characteristic curve of the frequency input and output response of the frequency selection and phase shift link built with the parameters shown in Table 1. From Figure 4 and Figure 5 it can be seen that the minimum value of the amplitude-frequency of the impedance characteristic of the frequency selection and phase shift link and the frequency corresponding to the minimum value are consistent with the calculated values during parameter design, thus verifying the effectiveness of the transfer function of the frequency input and output response corresponding to the frequency selection and phase shift link.

[0105] After adding the frequency selection and phase shift link corresponding to the parameters shown in Table 1 to the output end of the current loop of the grid-side converter of the doubly-fed wind turbine generator set, the amplitude-frequency characteristic and phase-frequency characteristic of the doubly-fed wind turbine generator set can be tested using the semi-physical simulation platform. Please refer to Figure 6 and Figure 7 , Figure 6 The figure is the result graph when testing the impedance amplitude-frequency characteristic of the doubly-fed wind turbine generator set using the semi-physical simulation platform. Figure 7 The figure is the result graph when testing the impedance phase-frequency characteristic of the doubly-fed wind turbine generator set using the semi-physical simulation platform. In Figure 6 and Figure 7 , the blue curve is the impedance sweep curve of the doubly-fed wind turbine generator set when no frequency selection and phase shift link is added to the output end of the current loop of the grid-side converter of the doubly-fed wind turbine generator set; the red curve is the impedance sweep curve of the doubly-fed wind turbine generator set when a frequency selection and phase shift link is added to the output end of the current loop of the grid-side converter of the doubly-fed wind turbine generator set. From Figure 6 and Figure 7 it can be seen that when a frequency selection and phase shift link is added to the output end of the current loop of the grid-side converter of the doubly-fed wind turbine generator set, the impedance phase of the doubly-fed wind turbine generator set in the frequency range of 0 - 20 Hz can be reduced, and the negative impedance characteristic of the doubly-fed wind turbine generator set can be eliminated. The phase of the doubly-fed wind turbine generator set at 20 Hz is reduced from 106.9° to 80.54°, thus demonstrating the effectiveness of the sub-synchronous oscillation method described in this application.

[0106] Please refer to Figure 8 , Figure 8 The figure is the structural diagram of a sub-synchronous oscillation suppression device for a doubly-fed wind turbine generator set provided by an embodiment of the present invention. The device includes:

[0107] A signal acquisition module 21, configured to obtain the voltage control signal of the doubly-fed wind turbine generator set in the synchronous rotating coordinate system to obtain a first voltage control signal when the doubly-fed wind turbine generator set is connected to the power grid through a series compensation capacitor;

[0108] The phase-shifting compensation module 22 is configured to extract the signal of the first voltage control signal within a specified frequency band range by using a filter, and perform phase-shifting compensation on the signal extracted by the filter by using a phase shifter with the goal that the doubly-fed wind turbine satisfies the positive impedance characteristic within the specified frequency band range, so as to obtain a second voltage control signal;

[0109] The signal control module 23 is configured to perform Park inverse transformation on the second voltage control signal to obtain a third voltage control signal, and use the third voltage control signal to control the three-phase alternating current output by the doubly-fed wind turbine, so that the three-phase alternating current output by the doubly-fed wind turbine is incorporated into the power grid.

[0110] Preferably, the phase-shifting compensation module 22 includes:

[0111] The signal extraction unit is configured to extract the signal of the first voltage control signal within the specified frequency band range by using the second-order band-pass filter, and perform phase-shifting compensation on the signal extracted by the second-order band-pass filter by using the phase shifter with the goal that the doubly-fed wind turbine satisfies the positive impedance characteristic within the specified frequency band range, so as to obtain a target signal;

[0112] The signal addition unit is configured to add the target signal and the signal of the first voltage control signal outside the specified frequency band range to obtain the second voltage control signal.

[0113] Preferably, it further includes:

[0114] The function acquisition unit is configured to acquire the frequency response transfer functions corresponding to the second-order band-pass filter and the phase shifter;

[0115] The expression of the frequency response transfer function is:

[0116] ;

[0117] In the formula, is the frequency response transfer function, is the damping parameter of the second-order band-pass filter, is the characteristic frequency of the second-order band-pass filter, is the damping parameter of the phase shifter, is the Laplace operator;

[0118] The parameter adjustment unit is configured to determine the minimum value of the amplitude of the frequency response transfer function, and with the goal that the minimum value of the amplitude of the frequency response transfer function is less than a preset threshold, adjust the damping parameter of the second-order band-pass filter, the characteristic frequency of the second-order band-pass filter, and the damping parameter Make adjustments.

[0119] Preferably, it further includes:

[0120] A parameter readjustment unit for adjusting the damping parameter of the second-order band-pass filter, the characteristic frequency of the second-order band-pass filter, and the damping parameter of the phase shifter to avoid a 180° phase jump in the impedance phase-frequency characteristics of the second-order band-pass filter and the phase shifter;

[0121] The expression of the target model is:

[0122] .

[0123] Preferably, it further includes:

[0124] A performance test unit for building a semi-physical simulation platform corresponding to the doubly-fed wind turbine based on the damping parameter of the second-order band-pass filter, the characteristic frequency of the second-order band-pass filter, and the damping parameter of the phase shifter and using the semi-physical simulation platform to test the amplitude-frequency characteristics and phase-frequency characteristics of the doubly-fed wind turbine.

[0125] The sub-synchronous oscillation suppression device for a doubly-fed wind turbine provided by an embodiment of the present invention has the beneficial effects of the sub-synchronous oscillation suppression method for a doubly-fed wind turbine disclosed above.

[0126] Please refer to Figure 9 , Figure 9 which is the structural diagram of a sub-synchronous oscillation suppression device for a doubly-fed wind turbine provided by an embodiment of the present invention. The device includes:

[0127] A memory 31 for storing a computer program;

[0128] A processor 32 for implementing the steps of the sub-synchronous oscillation suppression method for a doubly-fed wind turbine as disclosed above when executing the computer program.

[0129] The sub-synchronous oscillation suppression device for a doubly-fed wind turbine provided by an embodiment of the present invention has the beneficial effects of the sub-synchronous oscillation suppression method for a doubly-fed wind turbine disclosed above.

[0130] Correspondingly, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of a method for suppressing subsynchronous oscillation of a doubly-fed wind turbine as disclosed above are implemented.

[0131] The computer-readable storage medium provided by the embodiment of the present invention has the beneficial effects of a method for suppressing subsynchronous oscillation of a doubly-fed wind turbine as disclosed above.

[0132] In this specification, the various embodiments are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple. For the relevant parts, reference can be made to the description of the method part.

[0133] Finally, it should also be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0134] The above has introduced in detail a method for suppressing subsynchronous oscillation of a doubly-fed wind turbine and related devices provided by the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A method for suppressing subsynchronous oscillation of a doubly-fed wind turbine, characterized in that, Including: When a doubly-fed wind turbine is connected to the power grid through a series compensation capacitor, obtain the voltage control signal of the doubly-fed wind turbine in the synchronous rotating coordinate system to obtain a first voltage control signal; Use a filter to extract the signal of the first voltage control signal within a specified frequency band range, and use a phase shifter to perform phase shift compensation on the signal extracted by the filter with the goal that the doubly-fed wind turbine satisfies the positive impedance characteristic within the specified frequency band range to obtain a second voltage control signal; Perform an inverse Park transformation on the second voltage control signal to obtain a third voltage control signal, and use the third voltage control signal to control the three-phase alternating current output by the doubly-fed wind turbine so that the three-phase alternating current output by the doubly-fed wind turbine is incorporated into the power grid.

2. The method for suppressing subsynchronous oscillation of a doubly-fed wind turbine set according to claim 1, characterized in that The filter is specifically a second-order band-pass filter.

3. The sub-synchronous oscillation suppression method for a doubly-fed wind turbine set according to claim 2, wherein The step of using a filter to extract the signal of the first voltage control signal within a specified frequency band range, and using a phase shifter to perform phase shift compensation on the signal extracted by the filter with the goal that the doubly-fed wind turbine satisfies the positive impedance characteristic within the specified frequency band range to obtain a second voltage control signal includes: Use the second-order band-pass filter to extract the signal of the first voltage control signal within the specified frequency band range, and use the phase shifter to perform phase shift compensation on the signal extracted by the second-order band-pass filter with the goal that the doubly-fed wind turbine satisfies the positive impedance characteristic within the specified frequency band range to obtain a target signal; Add the target signal and the signal of the first voltage control signal outside the specified frequency band range to obtain the second voltage control signal.

4. A method for suppressing subsynchronous oscillation of a doubly-fed wind turbine according to claim 3, characterized in that, Also including: Obtain the frequency response transfer functions corresponding to the second-order band-pass filter and the phase shifter; The expression of the frequency response transfer function is: ； In the formula, is the frequency response transfer function, is the damping parameter of the second-order band-pass filter, is the characteristic frequency of the second-order band-pass filter, is the damping parameter of the phase shifter, is the Laplace operator; Determine the minimum value of the magnitude of the frequency response transfer function, and aim at the minimum value of the magnitude of the frequency response transfer function being less than a preset threshold, and adjust the damping parameter of the second-order band-pass filter , the characteristic frequency of the second-order band-pass filter and the damping parameter of the phase shifter for adjustment.

5. A method for suppressing subsynchronous oscillation of a doubly-fed wind turbine according to claim 4, characterized in that, The expression of the minimum value of the amplitude of the frequency response transfer function is: 。 6. A method for suppressing subsynchronous oscillation of a doubly-fed wind turbine according to claim 4, characterized in that, Also including: Based on the target model, the damping parameter of the second-order band-pass filter , the characteristic frequency of the second-order band-pass filter and the damping parameter of the phase shifter are adjusted to avoid a 180° phase jump in the impedance phase-frequency characteristics of the second-order band-pass filter and the phase shifter; The expression of the target model is: 。 7. A method for suppressing subsynchronous oscillation of a doubly-fed wind turbine according to claim 6, characterized in that, Also including: Based on the damping parameter of the second-order band-pass filter , the characteristic frequency of the second-order band-pass filter and the damping parameter of the phase shifter Build a semi-physical simulation platform corresponding to the doubly-fed wind turbine, and use the semi-physical simulation platform to test the amplitude-frequency characteristics and phase-frequency characteristics of the doubly-fed wind turbine.

8. A subsynchronous oscillation suppression device for a doubly-fed wind turbine, characterized in that, Including: A signal acquisition module, configured to obtain the voltage control signal of the doubly-fed wind turbine in the synchronous rotating coordinate system to obtain a first voltage control signal when the doubly-fed wind turbine is connected to the power grid through a series compensation capacitor; A phase shift compensation module, configured to use a filter to extract the signal of the first voltage control signal within a specified frequency band range, and use a phase shifter to perform phase shift compensation on the signal extracted by the filter with the goal that the doubly-fed wind turbine satisfies the positive impedance characteristic within the specified frequency band range to obtain a second voltage control signal; A signal control module, configured to perform an inverse Park transformation on the second voltage control signal to obtain a third voltage control signal, and use the third voltage control signal to control the three-phase alternating current output by the doubly-fed wind turbine so that the three-phase alternating current output by the doubly-fed wind turbine is incorporated into the power grid.

9. A subsynchronous oscillation suppression device for a doubly-fed wind turbine, characterized in that Including: A memory, configured to store a computer program; A processor, configured to implement the steps of a method for suppressing subsynchronous oscillation of a doubly-fed wind turbine according to any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that, A computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the steps of a method for suppressing subsynchronous oscillation of a doubly-fed wind turbine set according to any one of claims 1 to 7 are implemented.

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