A method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator system and related equipment

Abstract

The present application discloses a method for suppressing subsynchronous oscillations of a doubly-fed wind turbine and related equipment, belonging to the field of wind power generation technology. The method comprises: when the doubly-fed wind turbine is connected to the power grid via a series compensation capacitor, obtaining a voltage control signal of the doubly-fed wind turbine in a synchronous rotating coordinate system; using a filter to extract the voltage control signal within a specified frequency band, and using a phase shifter to perform phase shift compensation on the signal extracted by the filter with the goal of ensuring that the doubly-fed wind turbine satisfies the positive impedance characteristic within the specified frequency band; performing an inverse Park transform on the voltage control signal after phase shift compensation, and using the voltage control signal after the inverse Park transform to control the three-phase AC power output by the doubly-fed wind turbine. This method can solve the current technical problems of high cost, complex modeling, and difficulty in engineering application when suppressing subsynchronous oscillations of doubly-fed wind turbines.

Description

Technical Field

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

[0002] Doubly-fed wind turbines are widely used in wind power generation systems. They consist of components such as a doubly-fed induction generator (DFIG), a back-to-back converter, and a wind turbine box transformer. In practical applications, when the three-phase AC power output by a DFIG is fed into the grid, capacitors are typically connected in series with the DFIG's transmission line to improve transmission capacity. However, this compensation method also carries the risk of subsynchronous oscillations in the DFIG, seriously impacting the safe and stable operation of the DFIG.

[0003] In the prior art, two methods are commonly used to suppress subsynchronous oscillations generated by doubly-fed wind turbines. One method involves deploying hardware equipment at the grid end to suppress subsynchronous oscillations, such as broadband oscillation detection systems, phase regulators, and voltage regulators. However, this method is relatively expensive. Another method involves optimizing control parameters or employing additional virtual impedances at the turbine end of the doubly-fed wind turbine. However, this method requires the development of a mathematical model to analyze the impedance reshaping characteristics of the doubly-fed wind turbine. This mathematical modeling process is extremely complex, and control parameter optimization relies on time-domain simulation results. The mathematical model lacks analytical derivation for this process, making it impossible to more accurately quantify and analyze the control parameters of the doubly-fed wind turbine, hindering engineering application. Furthermore, this subsynchronous oscillation suppression method fails to consider the dynamic characteristics of the phase-locked loop (PLL) and control delay in the system in which the doubly-fed wind turbine resides during the mathematical modeling process, resulting in subsynchronous oscillation suppression effectiveness in the doubly-fed wind turbine that is less than expected. At present, there is no more effective solution to this technical problem. Summary of the Invention

[0004] In view of this, the present invention aims to provide a method, device, equipment, and medium for suppressing subsynchronous oscillations of a doubly-fed wind turbine generator set, in order to address the technical problems in the prior art of suppressing subsynchronous oscillations of doubly-fed wind turbines, such as high cost, complex modeling, and difficulty in engineering application. The specific solution is as follows:

[0005] In order to solve the above technical problems, the present invention provides a method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator system, comprising:

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

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

[0008] Performing a Park inverse transform on the second voltage control signal to obtain a third voltage control signal, and using the third voltage control signal to control the three-phase AC power output by the doubly fed wind turbine generator set so that the three-phase AC power output by the doubly fed wind turbine generator set is incorporated into the power grid.

[0009] Preferably, the filter is a second-order bandpass filter.

[0010] Preferably, the method of extracting the first voltage control signal within a specified frequency band by using a filter, and taking the doubly-fed wind turbine generator set satisfying a positive impedance characteristic within the specified frequency band as a goal, and performing phase shift compensation on the signal extracted by the filter by using a phase shifter to obtain the second voltage control signal includes:

[0011] Extracting a signal of the first voltage control signal within the specified frequency band using the second-order bandpass filter, and aiming at the doubly-fed wind turbine generator set satisfying a positive impedance characteristic within the specified frequency band, performing phase shift compensation on the signal extracted by the second-order bandpass filter using the phase shifter to obtain a target signal;

[0012] The target signal and the first voltage control signal are added together except for the designated frequency band to obtain the second voltage control signal.

[0013] Preferably, it also includes:

[0014] Obtaining frequency response transfer functions corresponding to the second-order bandpass filter and the phase shifter;

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

[0016] ;

[0017] Where, is the frequency response transfer function, is the damping parameter of the second-order bandpass filter, is the characteristic frequency of the second-order bandpass filter, is the damping parameter of the phase shifter, is the Laplace operator;

[0018] Determine the amplitude minimum of the frequency response transfer function, and with the amplitude minimum of the frequency response transfer function being less than a preset threshold as the goal, adjust the damping parameter of the second-order bandpass filter. , the characteristic frequency of the second-order bandpass filter and the damping parameters of the phase shifter Make adjustments.

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

[0020] .

[0021] Preferably, it also includes:

[0022] The damping parameters of the second-order bandpass filter based on the target model , the characteristic frequency of the second-order bandpass filter and the damping parameters of the phase shifter Adjusting to avoid a 180° phase jump in the impedance phase-frequency characteristics of the second-order bandpass filter and the phase shifter;

[0023] The expression of the target model is:

[0024] .

[0025] Preferably, it also includes:

[0026] Based on the damping parameters of the second-order bandpass filter , the characteristic frequency of the second-order bandpass filter and the damping parameters of the phase shifter A semi-physical simulation platform corresponding to the doubly-fed wind turbine generator set is built, and the amplitude-frequency characteristics and phase-frequency characteristics of the doubly-fed wind turbine generator set are tested using the semi-physical simulation platform.

[0027] In order to solve the above technical problems, the present invention further provides a subsynchronous oscillation suppression device for a doubly-fed wind turbine generator system, comprising:

[0028] a signal acquisition module, configured to acquire a voltage control signal of the doubly-fed wind turbine generator set in a synchronously rotating coordinate system when the doubly-fed wind turbine generator set is connected to a power grid via a series compensation capacitor, thereby obtaining a first voltage control signal;

[0029] a phase shift compensation module, configured to extract a signal of the first voltage control signal within a specified frequency band using a filter, and with the goal of ensuring that the doubly-fed wind turbine generator system satisfies a positive impedance characteristic within the specified frequency band, perform phase shift compensation on the signal extracted by the filter using a phase shifter to obtain a second voltage control signal;

[0030] A signal control module is used to perform a Park inverse transform 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 AC power output by the doubly fed wind turbine generator set so that the three-phase AC power output by the doubly fed wind turbine generator set is integrated into the power grid.

[0031] In order to solve the above technical problems, the present invention further provides a subsynchronous oscillation suppression device for a doubly-fed wind turbine generator system, comprising:

[0032] memory for storing computer programs;

[0033] The processor is configured to implement the steps of the method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator system disclosed above when executing the computer program.

[0034] In order to solve the above technical problems, the present invention also 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 the subsynchronous oscillation suppression method of a doubly-fed wind turbine generator system disclosed above are implemented.

[0035] Beneficial Effects: Compared to the prior art, the method provided by the present invention utilizes only filters and phase shifters to perform frequency selection and phase shifting on the voltage control signal of a doubly-fed wind turbine generator set in a synchronously rotating coordinate system. Furthermore, when the phase shifter is used to compensate for the phase shift of the signal extracted by the filter, with the goal of ensuring that the doubly-fed wind turbine generator set meets the positive impedance characteristic within a specified frequency band, the impedance characteristics of the doubly-fed wind turbine generator set within a specific frequency band can be adjusted and optimized, thereby suppressing the subsynchronous oscillations generated by the doubly-fed wind turbine generator set. Obviously, since this subsynchronous oscillation suppression method does not require the addition of hardware equipment on the grid side or the creation of complex mathematical models, it not only reduces the cost investment required to suppress subsynchronous oscillations, but also reduces the operational complexity of suppressing subsynchronous oscillations. Furthermore, in this method, the control parameters of the filter and phase shifter can be adjusted and optimized in real time according to actual needs, making it more convenient for engineering applications.

[0036] Correspondingly, the subsynchronous oscillation suppression device, equipment and medium of a doubly-fed wind turbine generator provided by the present invention also have the above-mentioned beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention 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 merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0038] Figure 1 A flow chart of a method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator system provided by an embodiment of the present invention;

[0039] Figure 2 This is a control diagram of adding a frequency selection and phase shifting link to the machine-side converter when controlling the grid connection of a doubly-fed wind turbine generator set;

[0040] Figure 3 This is the control block diagram of the frequency selection and phase shift link;

[0041] Figure 4 The frequency input and output response amplitude-frequency characteristic curve of the frequency selection and phase shifting link constructed using the parameters shown in Table 1;

[0042] Figure 5 The frequency input-output response phase-frequency characteristic curve of the frequency selection and phase shifting link constructed using the parameters shown in Table 1;

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

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

[0045] Figure 8 A structural diagram of a subsynchronous oscillation suppression device for a doubly-fed wind turbine generator system provided by an embodiment of the present invention;

[0046] Figure 9 This is a structural diagram of a subsynchronous oscillation suppression device for a doubly-fed wind turbine generator system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0048] See Figure 1 , Figure 1 A flowchart of a method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator system provided by an embodiment of the present invention includes:

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

[0050] Step S12: using a filter to extract a signal of the first voltage control signal within a specified frequency band, and with the goal of ensuring that the doubly-fed wind turbine generator system satisfies a positive impedance characteristic within the specified frequency band, using a phase shifter to perform phase shift compensation on the signal extracted by the filter to obtain a second voltage control signal;

[0051] Step S13: performing a Park inverse transform on the second voltage control signal to obtain a third voltage control signal, and using the third voltage control signal to control the three-phase AC power output by the doubly fed wind turbine generator set so that the three-phase AC power output by the doubly fed wind turbine generator set is integrated into the power grid.

[0052] In this embodiment, to suppress the subsynchronous oscillations generated by a doubly-fed wind turbine, the voltage control signal of the doubly-fed wind turbine in a synchronously rotating coordinate system is first acquired to obtain a first voltage control signal. Because the first voltage control signal includes control signals for other frequency bands unrelated to the subsynchronous oscillation frequency band, in order to adjust and optimize the impedance characteristics of the doubly-fed wind turbine in a specific frequency band, after obtaining the first voltage control signal, a filter is required to extract the first voltage control signal within the specified frequency band.

[0053] Specifically, in this embodiment, the dual closed-loop control system of the doubly-fed wind turbine generator's side converter is used to obtain the voltage control signal for the doubly-fed wind turbine generator in a synchronously rotating coordinate system. The dual closed-loop control system includes a power loop, a current loop, and a phase-locked loop (PLL). In other words, in this embodiment, the power loop, current loop, and PLL are used to obtain the voltage control signal for the doubly-fed wind turbine generator in a synchronously rotating coordinate system. Furthermore, based on actual application requirements, in this embodiment, the designated frequency band is set to 0–20 Hz.

[0054] When a filter is used to extract a signal of the first voltage control signal within a specified frequency band, a phase shifter is used to perform phase shift compensation on the signal extracted by the filter with the goal of ensuring that the doubly-fed wind turbine generator system satisfies the positive impedance characteristic within the specified frequency band to obtain a second voltage control signal, and a Park inverse transform is performed 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 AC 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 AC power output by the doubly fed wind turbine generator set, so that the three-phase AC power output by the doubly fed wind turbine generator set can be safely and stably integrated into the power grid.

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

[0057] In order 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 system involved in this application is briefly described here. Figure 2 , Figure 2 This is a control diagram for adding a frequency selection and phase shifting link to the machine-side converter when controlling the grid connection of a doubly fed wind turbine. When a doubly fed wind turbine is connected to the grid through a series capacitor, in order to allow the three-phase AC power generated by the doubly fed wind turbine to be connected to the grid, the first step is to use the double closed-loop control system of the machine-side converter 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. When the reference active power of the machine-side converter of the doubly fed induction wind turbine is , reference reactive power , actual active power and actual reactive power When passing through the power loop, a reference current of the machine-side converter in the synchronous rotating coordinate system is generated. and The reference current of the machine-side converter in the synchronous rotating coordinate system is and The actual current of the generator-side converter in the synchronous rotating coordinate system and When passing through the current loop, the reference voltage of the machine-side converter in the synchronous rotating coordinate system will be generated. , reference voltage That is the first voltage control signal.

[0058] Reference voltage After being processed by the frequency selection and phase shifting link, the second voltage control signal will be obtained , and the second voltage control signal After the Park inverse transformation and the phase-locked loop processing, a three-phase AC voltage is generated to regulate the doubly fed wind turbine. , three-phase AC voltage That is the third voltage control signal. Through the above closed-loop control process, the purpose of real-time regulation of the three-phase AC power output by the doubly-fed wind turbine generator set can be achieved, and subsynchronous oscillation of the doubly-fed wind turbine generator set can also be avoided.

[0059] Compared to the prior art, the method provided by the present invention utilizes only filters and phase shifters to perform frequency selection and phase shifting on the voltage control signal of a doubly-fed wind turbine generator set in a synchronously rotating coordinate system. Furthermore, when the phase shifter is used to compensate for the phase shift of the signal extracted by the filter, with the goal of ensuring that the doubly-fed wind turbine generator set meets the positive impedance characteristic within a specified frequency band, the impedance characteristics of the doubly-fed wind turbine generator set within the specified frequency band can be adjusted and optimized, thereby suppressing the subsynchronous oscillations generated by the doubly-fed wind turbine generator set. Obviously, since this subsynchronous oscillation suppression method does not require the addition of hardware equipment on the grid side or the creation of complex mathematical models, it not only reduces the cost investment required to suppress subsynchronous oscillations, but also reduces the operational complexity of suppressing subsynchronous oscillations. Furthermore, the control parameters of the filter and phase shifter can be adjusted and optimized in real time according to actual needs, making it more convenient for engineering applications.

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

[0061] Since the second-order bandpass filter has a simple circuit structure and low manufacturing cost, and the center frequency of the second-order bandpass filter can be changed by adjusting the parameter values ​​of the capacitor and inductor, this working performance of the second-order bandpass filter enables the second-order bandpass filter to adapt to different signal processing requirements, thereby significantly improving the convenience of the subsynchronous oscillation method described in this application in practical applications.

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

[0063] Formula 1: ;

[0064] Where, is the transfer function of the second-order bandpass filter, is the damping parameter of the second-order bandpass filter, is the characteristic frequency of the second-order bandpass filter, is the Laplace operator.

[0065] As a preferred embodiment, the above step of extracting the first voltage control signal within a specified frequency band using a filter, and using a phase shifter to perform phase shift compensation on the signal extracted by the filter with the goal of ensuring that the doubly-fed wind turbine generator system satisfies the positive impedance characteristic within the specified frequency band to obtain the second voltage control signal includes:

[0066] A second-order bandpass filter is used to extract the signal of the first voltage control signal within the specified frequency band, and with the goal of ensuring that the doubly-fed wind turbine generator system satisfies the positive impedance characteristic within the specified frequency band, a phase shifter is used to perform phase shift compensation on the signal extracted by the second-order bandpass filter to obtain a target signal;

[0067] The target signal and the first voltage control signal are added together except for the specified frequency band to obtain a second voltage control signal.

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

[0069] Formula 2: ;

[0070] Where, is the transfer function of the second-order bandpass filter, is the damping parameter of the phase shifter, is the Laplace operator.

[0071] Combining a second-order bandpass filter with a phase shifter can produce a frequency-selective phase shifter. Figure 3 , Figure 3 This is the control block diagram of the frequency selection and phase shift link. Figure 3 In the figure, 101 represents a second-order bandpass filter, 102 represents a phase shifter, and 103 represents a frequency selection phase shifting link. When the first voltage control signal is extracted by using the second-order bandpass filter 101 The signal within the specified frequency band is obtained by using the phase shifter 102 to compensate the phase of the signal extracted by the second-order bandpass filter 101, and the target signal is obtained by taking the double-fed wind turbine generator set satisfying the positive impedance characteristic within the specified frequency band as the goal. ; Then, the target signal and the first voltage control signal Remove the signal within the specified frequency band Add together to get 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 implementation, the above subsynchronous oscillation suppression method further includes:

[0074] Obtain the frequency response transfer function corresponding to the second-order bandpass filter and phase shifter;

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

[0076] ;

[0077] Where, is the frequency response transfer function, is the damping parameter of the second-order bandpass filter, is the characteristic frequency of the second-order bandpass filter, is the damping parameter of the phase shifter, is the Laplace operator;

[0078] Determine the amplitude minimum of the frequency response transfer function, and take the amplitude minimum of the frequency response transfer function as the goal to be less than the preset threshold, and adjust the damping parameters of the second-order bandpass filter. , the characteristic frequency of the second-order bandpass filter and the damping parameters of the phase shifter Make adjustments.

[0079] In this application, a frequency-selective phase-shifting link consisting of a second-order bandpass filter and a phase shifter is added to the output of the current loop of the doubly-fed wind turbine generator-side converter. Therefore, this link only increases or decreases the phase in the doubly-fed wind turbine generator's impedance characteristic curve without affecting the overall change trend of the doubly-fed wind turbine generator's impedance characteristic curve. Based on this characteristic of the frequency-selective phase-shifting link, we can roughly infer the change pattern of the doubly-fed wind turbine generator's impedance characteristic curve by analyzing the frequency-selective phase-shifting link.

[0080] In order to analyze the frequency selection and phase shifting link composed of the second-order bandpass filter and the phase shifter, in this embodiment, the frequency response transfer functions corresponding to the second-order bandpass filter and the phase shifter are first obtained.

[0081] The frequency response transfer function is expressed as:

[0082] Formula 3: ;

[0083] Where, is the frequency response transfer function, is the damping parameter of the second-order bandpass filter, is the characteristic frequency of the second-order bandpass 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, the frequency-selective phase shift link will have an amplitude minimum on the right side of the characteristic frequency of the second-order bandpass filter. As the value of the minimum amplitude increases, the frequency of the minimum amplitude shifts to the right, and the value corresponding to the minimum amplitude decreases. As the amplitude of the minimum value increases, the frequency of the amplitude minimum shifts to the left, and the value corresponding to the minimum value increases. According to the relevant mathematical model, the angular frequency corresponding to the minimum amplitude-frequency transfer function of the frequency-selective phase shift link can be calculated:

[0085] Formula 4: ;

[0086] The expression corresponding to the minimum amplitude at this time is:

[0087] Formula 5: ;

[0088] In practical applications, in order to improve the suppression effect of subsynchronous oscillation, we need to ensure that the amplitude-frequency reduction of the frequency-selective phase shifting link is relatively gentle, and the amplitude-frequency reduction of the frequency-selective phase shifting link cannot be too large. In this case, it is necessary to adjust the damping parameter of the second-order bandpass filter with the goal of making the minimum value of the amplitude of the frequency response transfer function less than the preset threshold. , the characteristic frequency of the second-order bandpass filter and the damping parameters of the phase shifter The preset threshold is a threshold set based on human experience to avoid subsynchronous oscillation of the doubly-fed wind turbine generator system.

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

[0090] Damping parameters of second-order bandpass filter based on target model , the characteristic frequency of the second-order bandpass filter and the damping parameters of the phase shifter Adjustments are made to avoid a 180° phase jump in the impedance-frequency characteristics of the second-order bandpass filter and phase shifter;

[0091] The expression of the target model is:

[0092] Formula 6: .

[0093] On the phase-frequency characteristic curve of the frequency-selective phase-shift link, the starting frequency point where the frequency-selective phase-shift link produces the phase-frequency adjustment characteristic is mainly affected by the characteristic frequency of the second-order bandpass filter. and damping parameters The cutoff frequency of the phase downshift section will be affected by the combined effect of the second-order bandpass filter and the phase shifter. When the impedance phase-frequency characteristics of the second-order bandpass filter and the phase shifter show a 180° phase jump, it means that the phase of the frequency selection phase shift link will be sharply reversed at certain frequencies, which will not only cause the output signal to be distorted and uncontrollable, but also cause strong oscillation. In order to avoid this phenomenon, it is necessary to use the target model to calculate the phase of the frequency selection phase shifter. To adjust the damping parameters of the second-order bandpass filter , the characteristic frequency of the second-order bandpass filter The damping parameters of the phase shifter are adjusted to avoid a 180° phase jump in the impedance phase-frequency characteristics of the second-order bandpass filter and the phase shifter.

[0094] Based on the above parameter design principles of the frequency selection and phase shifting link, the damping parameters of the second-order bandpass filter can be , the characteristic frequency of the second-order bandpass filter and the damping parameters of the phase shifter When adjusting the damping parameters of the second-order bandpass filter , the characteristic frequency of the second-order bandpass filter and the damping parameters of the phase shifter After adjustment, if the overall impedance characteristics of the system where the doubly fed wind turbine generator system is located within the specified frequency range, It can be determined that the doubly fed wind turbine meets the positive impedance characteristics within the specified frequency band.

[0095] Obviously, when using this method to suppress subsynchronous oscillations in doubly-fed wind turbines, since this method does not require the addition of hardware equipment on the grid side or the creation of complex mathematical models, it only requires adjusting the setting parameters of the second-order bandpass filter and phase shifter in the frequency selection and phase shifting link to achieve the purpose of suppressing subsynchronous oscillations. This not only reduces the cost investment required for suppressing subsynchronous oscillations, but also reduces the operational complexity of suppressing subsynchronous oscillations. In addition, in this method, the control parameters of the second-order bandpass filter and 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, the above subsynchronous oscillation suppression method further includes:

[0097] Damping parameters based on second-order bandpass filter , the characteristic frequency of the second-order bandpass filter and the damping parameters of the phase shifter A semi-physical simulation platform corresponding to the doubly-fed wind turbine generator set is built, and the amplitude-frequency characteristics and phase-frequency characteristics of the doubly-fed wind turbine generator set are tested using the semi-physical simulation platform.

[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 bandpass filter can also be used. , the characteristic frequency of the second-order bandpass filter and the damping parameters of the phase shifter To build a semi-physical simulation platform corresponding to the doubly fed wind turbine generator set, and use the semi-physical simulation platform to test the amplitude-frequency characteristics and phase-frequency characteristics of the doubly fed wind turbine generator set.

[0099] Specifically, the semi-physical simulation platform can be equipped with a real-time digital simulation system control cabinet, a wind turbine converter control simulation box, a wind turbine main controller, and a power amplifier for data exchange between the simulation model and the wind turbine main controller. The wind turbine converter control simulation box can control the start and stop of the wind turbine main controller and the grid connection of the doubly-fed wind turbine generator set through the host computer, thereby simulating the actual operating conditions of the doubly-fed wind turbine generator set.

[0100] Here, the subsynchronous oscillation method described in this application is specifically described by taking a certain wind farm doubly fed wind turbine generator system through a series compensation grid transmission system as an example. After oscillation risk assessment and stability analysis, it is required that the phase of the impedance characteristics of the doubly fed wind turbine generator system in the 0~20Hz frequency band satisfies the positive impedance characteristics, that is, the overall impedance characteristics of the system in which the doubly fed wind turbine generator system is located in the 0~20Hz frequency band is required to fall within the range of 0~20Hz. After the Park transform, this frequency band is converted to a frequency range of 30-50 Hz in a synchronously rotating coordinate system. Based on the aforementioned mathematical model derivation and calculations, the setting parameters for the second-order bandpass filter and phase shifter added to the output of the current loop of the doubly-fed wind turbine generator-side converter are shown in Table 1.

[0101] Table 1

[0102]

[0103] According to formula 4 and formula 5, it can be calculated that the minimum value of the impedance amplitude-frequency characteristic of the frequency selection and phase shifting link is -10.0dB. The impedance phase-frequency characteristic of the frequency-selective phase-shifting link does not cross 180°. The parameters shown in Table 1 are used to build the frequency-selective phase-shifting link in the hardware-in-the-loop simulation platform.

[0104] See Figure 4 and Figure 5 , Figure 4The frequency input and output response amplitude-frequency characteristic curve of the frequency selection and phase shifting link constructed using the parameters shown in Table 1 is as follows: Figure 5 The frequency input and output response phase-frequency characteristic curve of the frequency selection and phase shifting link is constructed using the parameters shown in Table 1. Figure 4 and Figure 5 It can be seen that the amplitude-frequency minimum value of the impedance characteristic of the frequency-selective phase-shift link and the frequency corresponding to the minimum value are consistent with the calculated value during parameter design, which verifies the validity of the frequency input-output response transfer function corresponding to the frequency-selective phase-shift link.

[0105] After adding the frequency selection and phase shifting link corresponding to the parameters described in Table 1 at the output end of the current loop of the DFIG wind turbine generator side converter, the amplitude-frequency and phase-frequency characteristics of the DFIG wind turbine generator can be tested using the semi-physical simulation platform. Figure 6 and Figure 7 , Figure 6 This is the result diagram of the impedance amplitude-frequency characteristics of the doubly fed wind turbine generator system tested using the semi-physical simulation platform. Figure 7 This is the result diagram of testing the impedance phase-frequency characteristics of the doubly fed wind turbine using a semi-physical simulation platform. Figure 6 and Figure 7 In the figure, the blue curve is the impedance sweep curve of the doubly fed wind turbine when the frequency selection and phase shift link is not added to the output end of the current loop of the doubly fed wind turbine machine side converter; the red curve is the impedance sweep curve of the doubly fed wind turbine when the frequency selection and phase shift link is added to the output end of the current loop of the doubly fed wind turbine machine side converter. Figure 6 and Figure 7 It can be seen that after adding a frequency-selective phase-shifting link at the output end of the current loop of the machine-side converter of the doubly fed wind turbine generator set, the impedance phase of the doubly fed wind turbine generator set in the frequency band of 0~20Hz can be reduced, and the negative impedance characteristics of the doubly fed wind turbine generator set can be eliminated. The phase of the doubly fed wind turbine generator set at a frequency of 20Hz is reduced from 106.9° to 80.54°, which illustrates the effectiveness of the subsynchronous oscillation method described in this application.

[0106] See Figure 8 , Figure 8 This is a structural diagram of a subsynchronous oscillation suppression device for a doubly-fed wind turbine generator system provided by an embodiment of the present invention, the device comprising:

[0107] a signal acquisition module 21 for acquiring a voltage control signal of the doubly-fed wind turbine generator set in a synchronously rotating coordinate system when the doubly-fed wind turbine generator set is connected to the power grid via a series compensation capacitor, thereby obtaining a first voltage control signal;

[0108] a phase compensation module 22 configured to extract a signal of the first voltage control signal within a specified frequency band using a filter, and to perform phase compensation on the signal extracted by the filter using a phase shifter with the goal of ensuring that the doubly-fed wind turbine generator system satisfies a positive impedance characteristic within the specified frequency band, thereby obtaining a second voltage control signal;

[0109] The signal control module 23 is used to perform a Park inverse transform 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 AC power output by the doubly fed wind turbine generator set so that the three-phase AC power output by the doubly fed wind turbine generator set is integrated into the power grid.

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

[0111] a signal extraction unit, configured to extract a signal of the first voltage control signal within the specified frequency band using the second-order bandpass filter, and to perform phase shift compensation on the signal extracted by the second-order bandpass filter using the phase shifter with the goal of the doubly-fed wind turbine generator set satisfying a positive impedance characteristic within the specified frequency band, thereby obtaining a target signal;

[0112] A signal adding unit is configured to add the target signal and the first voltage control signal except for the specified frequency band to obtain the second voltage control signal.

[0113] Preferably, it also includes:

[0114] A function acquisition unit, configured to acquire frequency response transfer functions corresponding to the second-order bandpass filter and the phase shifter;

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

[0116] ;

[0117] Where, is the frequency response transfer function, is the damping parameter of the second-order bandpass filter, is the characteristic frequency of the second-order bandpass filter, is the damping parameter of the phase shifter, is the Laplace operator;

[0118] The parameter adjustment unit is used to determine the amplitude minimum of the frequency response transfer function, and adjust the damping parameter of the second-order bandpass filter with the goal of making the amplitude minimum of the frequency response transfer function less than a preset threshold. , the characteristic frequency of the second-order bandpass filter and the damping parameters of the phase shifter Make adjustments.

[0119] Preferably, it also includes:

[0120] A parameter re-adjustment unit for adjusting the damping parameters of the second-order bandpass filter based on the target model , the characteristic frequency of the second-order bandpass filter and the damping parameters of the phase shifter Adjusting to avoid a 180° phase jump in the impedance phase-frequency characteristics of the second-order bandpass filter and the phase shifter;

[0121] The expression of the target model is:

[0122] .

[0123] Preferably, it also includes:

[0124] Performance testing unit for the damping parameters of the second-order bandpass filter based on , the characteristic frequency of the second-order bandpass filter and the damping parameters of the phase shifter A semi-physical simulation platform corresponding to the doubly-fed wind turbine generator set is built, and the amplitude-frequency characteristics and phase-frequency characteristics of the doubly-fed wind turbine generator set are tested using the semi-physical simulation platform.

[0125] An embodiment of the present invention provides a device for suppressing subsynchronous oscillations of a doubly-fed wind turbine generator set, which has the beneficial effects of the aforementioned method for suppressing subsynchronous oscillations of a doubly-fed wind turbine generator set.

[0126] See Figure 9 , Figure 9 This is a structural diagram of a subsynchronous oscillation suppression device for a doubly-fed wind turbine generator system provided by an embodiment of the present invention, the device comprising:

[0127] Memory 31, for storing computer programs;

[0128] The processor 32 is configured to implement the steps of the method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator system disclosed above when executing the computer program.

[0129] The subsynchronous oscillation suppression device of a doubly-fed wind turbine generator system provided in an embodiment of the present invention has the beneficial effects of the subsynchronous oscillation suppression method of the doubly-fed wind turbine generator system disclosed above.

[0130] Accordingly, 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 the subsynchronous oscillation suppression method of a doubly-fed wind turbine generator system disclosed above are implemented.

[0131] A computer-readable storage medium provided by an embodiment of the present invention has the beneficial effects of the aforementioned method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator system.

[0132] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. Reference can be made to the descriptions of the identical or similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and the relevant parts can be referred to the descriptions of the methods.

[0133] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only 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 terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0134] The above is a detailed introduction to the subsynchronous oscillation suppression method and related equipment of a doubly fed wind turbine provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for general technical personnel in this field, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator system, characterized in that: include: When the doubly-fed wind turbine generator set is connected to the power grid through the series compensation capacitor, a voltage control signal of the doubly-fed wind turbine generator set in a synchronous rotating coordinate system is obtained to obtain a first voltage control signal; A filter is used to extract a signal of the first voltage control signal within a specified frequency band, and with the goal of ensuring that the doubly-fed wind turbine generator system satisfies a positive impedance characteristic within the specified frequency band, a phase shifter is used to perform phase shift compensation on the signal extracted by the filter to obtain a second voltage control signal; Performing a Park inverse transform on the second voltage control signal to obtain a third voltage control signal, and using the third voltage control signal 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 is incorporated into the power grid; The filter is specifically a second-order bandpass filter; The method of extracting a signal of the first voltage control signal within a specified frequency band by using a filter, and taking the doubly-fed wind turbine generator set satisfying a positive impedance characteristic within the specified frequency band as a goal, and performing phase shift compensation on the signal extracted by the filter by using a phase shifter to obtain a second voltage control signal includes: Extracting a signal of the first voltage control signal within the specified frequency band using the second-order bandpass filter, and aiming at the doubly-fed wind turbine generator set satisfying a positive impedance characteristic within the specified frequency band, performing phase shift compensation on the signal extracted by the second-order bandpass filter using the phase shifter to obtain a target signal; Adding the target signal and the first voltage control signal except for the specified frequency band to obtain the second voltage control signal; Also includes: Obtaining frequency response transfer functions corresponding to the second-order bandpass filter and the phase shifter; The expression of the frequency response transfer function is: ； Where, is the frequency response transfer function, is the damping parameter of the second-order bandpass filter, is the characteristic frequency of the second-order bandpass filter, is the damping parameter of the phase shifter, is the Laplace operator; Determine the amplitude minimum of the frequency response transfer function, and with the amplitude minimum of the frequency response transfer function being less than a preset threshold as the goal, adjust the damping parameter of the second-order bandpass filter. , the characteristic frequency of the second-order bandpass filter and the damping parameters of the phase shifter Make adjustments.

2. The method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator system according to claim 1, characterized in that: The expression for the amplitude minimum of the frequency response transfer function is: 。 3. The method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator system according to claim 1, characterized in that: Also includes: The damping parameters of the second-order bandpass filter based on the target model , the characteristic frequency of the second-order bandpass filter and the damping parameters of the phase shifter Adjusting to avoid a 180° phase jump in the impedance phase-frequency characteristics of the second-order bandpass filter and the phase shifter; The expression of the target model is: 。 4. The method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator system according to claim 3, characterized in that: Also includes: Based on the damping parameters of the second-order bandpass filter , the characteristic frequency of the second-order bandpass filter and the damping parameters of the phase shifter A semi-physical simulation platform corresponding to the doubly-fed wind turbine generator set is built, and the amplitude-frequency characteristics and phase-frequency characteristics of the doubly-fed wind turbine generator set are tested using the semi-physical simulation platform.

5. A subsynchronous oscillation suppression device for a doubly-fed wind turbine generator system, characterized in that: include: a signal acquisition module, configured to acquire a voltage control signal of the doubly-fed wind turbine generator set in a synchronously rotating coordinate system when the doubly-fed wind turbine generator set is connected to a power grid via a series compensation capacitor, thereby obtaining a first voltage control signal; a phase shift compensation module, configured to extract a signal of the first voltage control signal within a specified frequency band using a filter, and with the goal of ensuring that the doubly-fed wind turbine generator system satisfies a positive impedance characteristic within the specified frequency band, perform phase shift compensation on the signal extracted by the filter using a phase shifter to obtain a second voltage control signal; a signal control module, configured to perform an inverse Park transform 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 generator set so that the three-phase alternating current output by the doubly-fed wind turbine generator set is incorporated into the power grid; The filter is specifically a second-order bandpass filter; The phase compensation module is specifically configured to: extract the signal of the first voltage control signal within the specified frequency band using the second-order bandpass filter, and with the goal of the doubly-fed wind turbine generator set satisfying the positive impedance characteristic within the specified frequency band, perform phase compensation on the signal extracted by the second-order bandpass filter using the phase shifter to obtain a target signal; and add the target signal and the signal of the first voltage control signal excluding the specified frequency band to obtain the second voltage control signal; The subsynchronous oscillation suppression device of the doubly-fed wind turbine generator set is further used to: obtain the frequency response transfer function corresponding to the second-order bandpass filter and the phase shifter; The expression of the frequency response transfer function is: ； Where, is the frequency response transfer function, is the damping parameter of the second-order bandpass filter, is the characteristic frequency of the second-order bandpass filter, is the damping parameter of the phase shifter, is the Laplace operator; Determine the amplitude minimum of the frequency response transfer function, and with the amplitude minimum of the frequency response transfer function being less than a preset threshold as the goal, adjust the damping parameter of the second-order bandpass filter. , the characteristic frequency of the second-order bandpass filter and the damping parameters of the phase shifter Make adjustments.

6. A subsynchronous oscillation suppression device for a doubly-fed wind turbine generator system, characterized in that: include: memory for storing computer programs; A processor is configured to implement the steps of the method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator set as claimed in any one of claims 1 to 4 when executing the computer program.

7. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator set according to any one of claims 1 to 4 are implemented.

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