Broadband power grid harmonic wave tracking suppression method

Abstract

The invention discloses a broadband power grid harmonic tracking suppression method, which comprises the following steps of: applying an adaptive phase-locked loop module to a cascaded double-second-order generalized integrator, and constructing an adaptive cascaded double-second-order generalized integrator phase-locked loop model; inputting the broadband power grid voltage into an adaptive cascade dual-second-order generalized integrator phase-locked loop model, correcting parameters in an adaptive phase-locked loop module in real time based on the fundamental frequency of the broadband power grid voltage, and adaptively changing the bandwidth of a phase-locked loop to obtain a power grid adaptive frequency changing along with the broadband power grid frequency; based on the self-adaptive frequency of the power grid, a self-adaptive cascade double-second-order generalized integrator phase-locked loop model extracts an orthogonal component and positive and negative sequence components of a harmonic frequency changing along with the frequency of the broadband power grid from the harmonic wave of the voltage of the broadband power grid; and the extracted orthogonal component is fed back to the harmonic subtraction module to suppress the harmonic in the broadband power grid voltage, so that a relatively good harmonic extraction suppression effect is achieved.

Description

Technical Field

[0001] The present invention relates to the field of new energy power technology, and in particular to a broadband power grid harmonic tracking and suppression method. Background Art

[0002] With the development of new energy technologies, the proportion of renewable energy such as wind energy and solar energy in the global energy structure continues to rise. These new energy power generation systems mostly use power electronic devices such as inverters for energy conversion, which improves energy utilization efficiency while also bringing about the problem of harmonic pollution in the power grid. Harmonics are a common power quality problem in power systems, which can lead to a series of problems such as reduced energy efficiency, equipment overheating, and malfunction of protection devices. Therefore, in a wide-band power grid accompanied by harmonic interference, it is of great significance to accurately estimate the power grid voltage information and further accurately extract and suppress the power grid harmonics for the power grid quality and the reliability of the electrical system. The cascaded dual second-order generalized integrator phase-locked loop method has good performance for harmonic extraction under the industrial frequency power grid. The wide band has a wide frequency variation range. If the frequency variation falls outside the range of the phase-locked loop, the system becomes unstable and the power grid voltage information cannot be estimated, which significantly reduces the performance of the harmonic extraction method in the wide-band power grid, resulting in unstable oscillations, which in turn affects the extraction and suppression of harmonics. Summary of the invention

[0003] In order to overcome the shortcomings of the prior art, the present invention provides a wide-band power grid harmonic tracking and suppression method, which can accurately track the frequency and positive and negative sequence components in a wide-band power grid and accompanied by harmonics, accurately extract the positive and negative sequence components of each harmonic, and has a good harmonic suppression effect.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: to provide a broadband power grid harmonic tracking and suppression method, which comprises the following steps:

[0005] The adaptive phase-locked loop module is applied to the cascaded biquad generalized integrator to construct an adaptive cascaded biquad generalized integrator phase-locked loop model;

[0006] The broadband grid voltage is input into an adaptive cascaded dual second-order generalized integrator phase-locked loop model, and the parameters in the adaptive phase-locked loop module are modified based on the fundamental frequency of the broadband grid voltage to obtain a grid adaptive frequency that follows the broadband grid frequency.

[0007] Based on the grid adaptive frequency, an adaptive cascaded dual second-order generalized integrator phase-locked loop model extracts the orthogonal components and positive and negative sequence components of the harmonic frequencies that vary with the broadband grid frequency from the harmonics of the broadband grid voltage.

[0008] Preferably, the method of applying the adaptive phase-locked loop module to a cascaded biquad generalized integrator to construct an adaptive cascaded biquad generalized integrator phase-locked loop model specifically includes:

[0009] Constructing a cascaded biquad generalized integrator, wherein the cascaded biquad generalized integrator comprises at least two biquad generalized integrators connected in parallel;

[0010] The adaptive phase-locked loop module is applied to the cascaded dual second-order generalized integrator, so that the feedback end of the adaptive phase-locked loop module is connected with the input end of the cascaded dual second-order generalized integrator to form an adaptive cascaded dual second-order generalized integrator phase-locked loop model.

[0011] Preferably, the cascaded biquad generalized integrator includes a fundamental biquad generalized integrator and at least one harmonic biquad generalized integrator.

[0012] Preferably, the method of modifying the parameters in the adaptive phase-locked loop module based on the fundamental frequency of the broadband grid voltage to obtain a grid adaptive frequency that follows the broadband grid frequency changes, specifically includes:

[0013] Input the broadband grid voltage into the fundamental biquad generalized integrator to obtain the orthogonal signal of the fundamental frequency;

[0014] The orthogonal signal of the fundamental frequency is fed back to the adaptive phase-locked loop module to modify the parameters of the adaptive phase-locked loop module, so that the adaptive phase-locked loop module outputs a grid adaptive frequency that follows the fundamental frequency.

[0015] Preferably, according to the grid adaptive frequency, the cascaded double second-order generalized integrator extracts the harmonic quadrature components and positive and negative sequence components that vary with the wide-band grid frequency from the harmonics of the wide-band grid voltage; specifically includes:

[0016] Feeding back the grid adaptive frequency to the fundamental wave biquad generalized integrator to output the positive and negative sequence components of the grid adaptive frequency;

[0017] The positive and negative sequence components of the grid adaptive frequency are fed back to the harmonic biquad generalized integrator to extract the harmonic orthogonal components and positive and negative sequence components that vary with the wide-band grid frequency.

[0018] Preferably, before inputting the wideband grid voltage into the fundamental biquad generalized integrator, the coordinates of the wideband grid voltage need to be converted, that is, the three-phase wideband grid voltage is converted from a three-phase stationary coordinate system to a grid voltage component in a two-phase stationary coordinate system.

[0019] Preferably, when the harmonic content in the broadband power grid increases, the cascaded biquad generalized integrator includes a plurality of harmonic biquad generalized integrators.

[0020] Preferably, when the harmonic content in the broadband power grid increases, the operating frequency of the harmonic biquad generalized integrator is set to the power grid frequency multiplied by the corresponding harmonic order; and the k value in the biquad generalized integrator module is divided by the corresponding harmonic order.

[0021] Preferably, the output end of each biquad generalized integrator in the cascaded biquad generalized integrator is connected to the positive / negative sequence component calculation module.

[0022] Preferably, the input end of each of the cascaded biquad generalized integrators is provided with a coordinate conversion module and a harmonic subtraction module, wherein:

[0023] The coordinate conversion module is used to convert the three-phase broadband power grid voltage from the three-phase stationary coordinate system to the broadband power grid voltage component in the two-phase stationary coordinate system;

[0024] The forward input end of the harmonic subtraction module is connected to the output end of the coordinate conversion module, the reverse input end of the harmonic subtraction module is connected to the orthogonal component output ends of other biquad generalized integrators except the current biquad generalized integrator; the output end of the harmonic subtraction module is connected to the current biquad generalized integrator.

[0025] The beneficial effects of the present invention are:

[0026] The invention provides a method for tracking and suppressing harmonics in a wide-band power grid, which feeds back the fundamental frequency of the wide-band power grid voltage to an adaptive phase-locked loop module, so that the control parameters of the adaptive phase-locked loop module are corrected in real time as the fundamental frequency changes, and the bandwidth of the phase-locked loop is adaptively changed, so that it can be more adaptable to the frequency change of the wide-band power grid and has a better frequency tracking effect; then the power grid adaptive frequency output by the adaptive phase-locked loop module is fed back to a cascaded double second-order generalized integrator, so that the operating frequency in the cascaded double second-order generalized integrator changes as the power grid adaptive frequency changes, and then the positive and negative sequence components of the harmonics can be accurately extracted and suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a model structure diagram of the adaptive cascaded dual second-order generalized integrator phase-locked loop model described in an embodiment of the present invention.

[0028] Figure 2 It is a model structure diagram of the biquadric generalized integrator described in an embodiment of the present invention.

[0029] Figure 3 It is a model structure diagram of the adaptive phase-locked loop described in an embodiment of the present invention.

[0030] Figure 4The adaptive cascaded biquad generalized integrator phase-locked loop model and the cascaded biquad generalized integrator phase-locked loop model described in the embodiments of the present invention are the frequency estimation experimental results of a small frequency jump of 450-460Hz in a wide-band power grid and accompanied by harmonics at 460Hz.

[0031] Figure 5 The adaptive cascaded dual-quad generalized integrator phase-locked loop model and the cascaded dual-quad generalized integrator phase-locked loop model described in the embodiments of the present invention are frequency estimation experimental results of a large frequency jump of 450-600Hz in a wide-band power grid and accompanied by harmonics at 600Hz.

[0032] Figure 6 The adaptive cascaded dual-quad generalized integrator phase-locked loop model and the cascaded dual-quad generalized integrator phase-locked loop model described in the embodiments of the present invention are experimental results of positive and negative sequence component state estimation with a small frequency jump of 450-460Hz and accompanied by harmonics at 460Hz in a wide-band power grid.

[0033] Figure 7 The adaptive cascaded dual-second-order generalized integrator phase-locked loop model and the cascaded dual-second-order generalized integrator phase-locked loop model described in the embodiments of the present invention are experimental results of state estimation of positive and negative sequence components with large frequency jumps of 450-600Hz and accompanied by harmonics at 600Hz in a wide-band power grid. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0035] In the grid-connected converter, ensuring that the correct positive and negative sequence components of the current frequency can be accurately controlled and injected is the core of achieving efficient and stable synchronization with the grid; therefore, the grid synchronization system needs to be able to accurately track the positive and negative sequence components of the grid voltage at the grid access point, which is crucial to ensuring system stability and improving power quality. Therefore, in a wide-band grid accompanied by harmonics, accurately tracking the frequency and positive and negative sequence components, and accurately extracting the positive and negative sequence components of each harmonic, can produce a good harmonic suppression effect; and it has important practical significance for improving power quality, protecting grid equipment, and promoting the better integration of new energy into the grid.

[0036] Based on this, an embodiment of the present invention provides a broadband power grid harmonic tracking and suppression method, which includes the following steps:

[0037] S1. Apply the adaptive phase-locked loop module to the cascaded dual second-order generalized integrator to construct an adaptive cascaded dual second-order generalized integrator phase-locked loop model;

[0038] S2, inputting the broadband grid voltage into the adaptive cascaded dual second-order generalized integrator phase-locked loop model, and modifying the parameters in the adaptive phase-locked loop module based on the fundamental frequency of the broadband grid voltage to obtain a grid adaptive frequency that follows the broadband grid frequency;

[0039] S3. Based on the grid adaptive frequency, the adaptive cascaded dual second-order generalized integrator phase-locked loop model extracts the orthogonal components and positive and negative sequence components of the harmonic frequency that changes with the wide-band grid frequency from the harmonics of the wide-band grid voltage.

[0040] That is, the fundamental frequency of the wide-band grid voltage is fed back to the adaptive phase-locked loop module, so that the control parameters of the adaptive phase-locked loop module are corrected in real time with the change of the fundamental frequency, and the bandwidth of the phase-locked loop is adaptively changed, so that it can be more adaptable to the change of the wide-band grid frequency and have a better frequency tracking effect; then the grid adaptive frequency output by the adaptive phase-locked loop module is fed back to the cascaded double second-order generalized integrator, so that the resonant frequency in the cascaded double second-order generalized integrator changes with the change of the grid adaptive frequency, and then the positive and negative sequence components of the harmonics can be accurately extracted and suppressed.

[0041] Specifically, the construction method of the adaptive cascaded dual-quadrant generalized integrator phase-locked loop model is as follows:

[0042] A cascaded dual second-order generalized integrator is constructed, and an adaptive phase-locked loop module is applied to the cascaded dual second-order generalized integrator, so that the feedback end of the adaptive phase-locked loop module is connected to the input end of the cascaded dual second-order generalized integrator to form an adaptive cascaded dual second-order generalized integrator phase-locked loop model. The cascaded dual second-order generalized integrator includes at least two parallel dual second-order generalized integrators. Specifically, the cascaded dual second-order generalized integrator includes a fundamental dual second-order generalized integrator and at least one harmonic dual second-order generalized integrator. The cascaded dual second-order generalized integrator decomposes the fundamental and harmonics of the broadband power grid voltage through the fundamental dual second-order generalized integrator and the harmonic dual second-order generalized integrator.

[0043] like Figure 1 As shown, the input end of each of the cascaded dual second-order generalized integrators is provided with a coordinate conversion module and a harmonic subtraction module; the coordinate conversion module is used to convert the three-phase broadband power grid voltage from a three-phase stationary coordinate system to a broadband power grid voltage component under a two-phase stationary coordinate system. The positive input end of the harmonic subtraction module is connected to the output end of the coordinate conversion module, and the reverse input end of the harmonic subtraction module is connected to the orthogonal component output end of other dual second-order generalized integrators except the current dual second-order generalized integrator; the output end of the harmonic subtraction module is connected to the current dual second-order generalized integrator.

[0044] At the same time, if Figure 1As shown, the output end of each dual second-order generalized integrator is connected to a positive / negative sequence component calculation module (PNSC). The fundamental dual second-order generalized integrator phase-locked loop structure combined with the positive / negative sequence component calculation module can extract the positive and negative sequence components of the fundamental frequency of the broadband power grid; the harmonic dual second-order generalized integrator phase-locked loop structure combined with the positive / negative sequence component calculation module can extract the positive and negative sequence components of the harmonic frequency of the broadband power grid.

[0045] The model structure diagram of the adaptive cascaded dual second-order generalized integrator phase-locked loop method is as follows: Figure 1 After the adaptive cascaded dual second-order generalized integrator phase-locked loop model is constructed, the wide-band grid voltage is input into the adaptive cascaded dual second-order generalized integrator phase-locked loop model, and the orthogonal components of the fundamental frequency are obtained from the fundamental dual second-order generalized integrator output; and the orthogonal components of the fundamental frequency are fed back to the adaptive phase-locked loop module, and the parameters of the adaptive phase-locked loop module are corrected; so that the adaptive phase-locked loop module outputs a grid adaptive frequency that follows the changes of the fundamental frequency.

[0046] However, since the broadband grid voltage is a three-phase voltage, in a three-phase power system, the asymmetric coordinates of the three-phase voltage will not only affect the system efficiency, but also the grid quality. In order to effectively analyze and deal with this asymmetry phenomenon, the symmetrical component method is used to convert the voltage v abc In the case of asymmetry, the instantaneous positive sequence, negative sequence and zero sequence are decomposed, that is, The specific formula is as follows:

[0047] (1)

[0048] (2)

[0049] (3)

[0050] In formula (1), (2) and (3), v abc is the three-phase grid voltage, the superscripts +, -, and 0 represent the positive sequence, negative sequence, and zero sequence components of the voltage vector v, respectively. + ] is the positive sequence transformation matrix, [T - ] is the negative sequence transformation matrix, [T0] is the zero sequence transformation matrix, and a is a special form of the Fortescue operator, which means adding a 120° phase shift of the fundamental frequency to the instantaneous sinusoidal input signal.

[0051] Then, in the stationary αβ reference coordinate system, the positive and negative sequence components of the fundamental frequency and harmonic frequency of the broadband grid voltage can be calculated and obtained by further mathematical processing;

[0052] (4)

[0053] (5)

[0054] In formula (4) and (5), and is the two-phase grid voltage The positive and negative sequence voltage component vectors, is the transformation matrix from the abc three-phase coordinate system to the two-phase αβ coordinate system, yes The inverse transformation of the matrix, [T + ] is the positive sequence transformation matrix, [T - ] is the negative sequence transformation matrix, q (q=e-jπ / 2) is a 90° lagging shift operation. Applying it in the time domain can obtain the quadrature axis component of the input waveform. Figure 2 is the model structure diagram of the biquadric generalized integrator, such as Figure 2 As shown, in the structure of the biquad generalized integrator, the input grid voltage v α and v β Through the biquad generalized integrator-quadrature signal generator, direct-axis and quadrature-axis signals are generated respectively, for example , , and Then, the positive and negative sequence components of the grid frequency are extracted from the above signal by the positive / negative sequence component calculation module, and the calculation formula is given by equation (4) and equation (5). The gain of the biquadruple generalized integrator-orthogonal signal generator is k=1.414.

[0055] Therefore, after the broadband grid voltage is input into the adaptive cascaded dual second-order generalized integrator phase-locked loop model, the coordinates of the broadband grid voltage must be transformed first, that is, the three-phase broadband grid voltage By Clark transformation, the three-phase stationary coordinate system v abc Converted into the broadband grid voltage component v in the two-phase stationary coordinate system αβ Then the converted broadband grid voltage component v αβ As the input signal of the harmonic subtraction module (HDN).

[0056] like Figure 1 As shown, the positive input end of the harmonic subtraction module is connected to the output end of the coordinate conversion module, and the negative input end of the harmonic subtraction module is connected to the orthogonal component output end of other biquad generalized integrators except the current biquad generalized integrator; therefore, the converted broadband grid voltage component v αβAfter inputting into the harmonic subtraction module, the v' in the fundamental frequency quadrature component of the broadband grid voltage extracted by other biquad generalized integrators and the v' in the harmonic frequency quadrature component are subtracted in the harmonic subtraction module, so that a single frequency signal is output after passing through the harmonic subtraction module. The single frequency signal output by the harmonic subtraction module is input into the fundamental biquad generalized integrator, and the quadrature signal of the fundamental frequency of the broadband grid voltage is output. and .

[0057] PI parameters in phase-locked loop and wide-band power grid frequency The coupling relationship between them is as follows:

[0058] (6)

[0059] (7)

[0060] Based on PI parameters in phase-locked loop and wide-band power grid frequency The coupling relationship between them is used to construct an adaptive phase-locked loop module (APLL). The model structure diagram of the adaptive phase-locked loop module is shown in Figure 3 As shown. The generated grid frequency signal is input into the adaptive phase-locked loop module to correct the PI parameters of the adaptive phase-locked loop module in real time. That is, the orthogonal component of the fundamental frequency output by the dual second-order generalized integrator is fed back to the parameter k of the PI controller of the adaptive phase-locked loop module. p and k i In the process, the parameters of the PI controller are modified in real time with the change of the fundamental frequency, and the bandwidth of the phase-locked loop is adaptively changed. The adaptive phase-locked loop module outputs the grid adaptive frequency that follows the change of the fundamental frequency. The grid adaptive frequency can be more adaptable to the change of the wide-band grid frequency, accurately track the wide-band grid frequency, and provide accurate grid frequency information for the input of the harmonic biquad generalized integrator.

[0061] After obtaining the grid adaptive frequency, the grid adaptive frequency is fed back to the fundamental double second-order generalized integrator to output the positive and negative sequence components of the grid adaptive frequency; finally, the grid adaptive frequency is fed back to the harmonic double second-order generalized integrator to extract the harmonic orthogonal components and positive and negative sequence components that change with the wide-band grid frequency, and then the extracted harmonic orthogonal components are fed back to the HDN module for subtraction, which can effectively eliminate the harmonics in the wide-band grid.

[0062] Specifically, the grid adaptive frequency output by the adaptive phase-locked loop module is fed back to the fundamental dual second-order generalized integrator again, and the positive and negative sequence components of the grid adaptive frequency are extracted by combining the fundamental dual second-order generalized integrator with the positive / negative sequence component calculation module. Then the orthogonal components of the grid adaptive frequency are fed back to the harmonic subtraction module at the input end of the harmonic dual second-order generalized integrator, and subtracted from the harmonic frequency of the wide-band grid voltage in the harmonic subtraction module; according to the real-time correction of the harmonic frequency by the adaptive phase-locked loop module, the resonant frequency in the harmonic dual second-order generalized integrator changes with the change of the wide-band grid frequency, and finally the positive and negative sequence components of the wide-band harmonic frequency are extracted by combining the harmonic dual second-order generalized integrator with the positive / negative sequence component calculation module, so that the positive and negative sequence components of the harmonics can be accurately extracted and suppressed.

[0063] In addition, when the harmonic content in the broadband power grid increases, the cascaded dual second-order generalized integrator may include multiple parallel harmonic dual second-order generalized integrators to improve the processing capability of the system, so that the model can not only accurately obtain the grid frequency information, but also identify and extract the positive and negative sequence components of each harmonic in the broadband power grid, thereby effectively eliminating the harmonics in the broadband power grid. Specifically, when the cascaded dual second-order generalized integrator includes multiple parallel harmonic dual second-order generalized integrators, the operating frequency of the harmonic dual second-order generalized integrator is set to the grid frequency multiplied by the corresponding harmonic order; and the k value in the dual second-order generalized integrator module is divided by the corresponding harmonic order.

[0064] The wideband power grid harmonic tracking and suppression method proposed in the embodiment of the present invention feeds back the power grid frequency output by the dual second-order generalized integrator phase-locked loop to the adaptive phase-locked loop module, so that the PI parameters in the adaptive phase-locked loop module are corrected in real time as the power grid frequency changes, and the bandwidth of the phase-locked loop is adaptively changed, so that the resonant frequency changes as the power grid frequency changes, and then the positive and negative sequence components of the harmonics are accurately extracted and suppressed, thereby achieving a better harmonic extraction and suppression effect.

[0065] In order to verify the effectiveness of the harmonic extraction and suppression method proposed in the present invention for broadband power grid harmonic tracking and suppression under broadband power grid accompanying harmonic conditions, the performance of the adaptive cascaded dual second-order generalized integrator phase-locked loop model (AMDSOGI-PLL) and the cascaded dual second-order generalized integrator phase-locked loop model (MDSOGI-PLL) adopted by the broadband power grid harmonic tracking and suppression method of the present invention under different power grid conditions are compared experimentally. Among them, the coefficient k of the PI controller in the cascaded dual second-order generalized integrator phase-locked loop model (MDSOGI-PLL) is p =222.1, k i =11974.

[0066] like Figure 4 and Figure 6 As shown in the figure, the experimental results of two phase-locked loop models with a small frequency jump and accompanying harmonics in a wide-band power grid are shown. The wide-band power grid frequency jumps from 450Hz to 460Hz, and is accompanied by harmonics at 460Hz. The harmonic components contain 5th and 7th harmonics, where V5=0.1 and V7=0.05. The proposed AMDSOGI-PLL can accurately estimate the wide-band power grid frequency within 4ms, and its dynamic speed is faster than MDSOGI-PLL. In addition, both AMDSOGI-PLL and MDSOGI-PLL can accurately extract the positive and negative sequence components of the wide-band power grid frequency and harmonics under small frequency jumps. When extracting the negative sequence component, AMDSOGI-PLL is faster than MDSOGI-PLL. It can be seen that AMDSOGI-PLL has a shorter adjustment time and higher stability.

[0067] Figure 5 and Figure 7 The experimental results of two phase-locked loops with a large frequency jump and accompanying harmonics in a wide-band power grid are shown. The wide-band power grid frequency jumps from 450Hz to 600Hz, and is accompanied by harmonics at 600Hz. The harmonic components contain 5th and 7th harmonics, where V5=0.1 and V7=0.05. The proposed AMDSOGI-PLL can accurately estimate the power grid frequency within 6ms, and its dynamic speed is faster than MDSOGI-PLL. MDSOGI-PLL will oscillate under large frequency jumps and cannot estimate the wide-band power grid frequency. By comparison, it can be seen that AMDSOGI-PLL has better stability. In addition, AMDSOGI-PLL can accurately extract the positive and negative sequence components of the wide-band power grid frequency and harmonics at large frequencies. The amplitude of the positive sequence component of the frequency estimated by MDSOGI-PLL becomes smaller, and the estimation is inaccurate. In other cases, continuous oscillation occurs, making the system unstable. By comparison, it can be seen that AMDSOGI-PLL can more accurately track the positive and negative sequence components of the wide-band grid frequency and harmonics under the conditions of wide-band grid accompanied by harmonics. At the same time, it can more accurately extract the positive and negative sequence components of harmonics and has a better suppression effect on harmonics.

[0068] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0069] Those of ordinary skill in the art will appreciate that the modules, units and / or method steps of the various embodiments described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0070] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A broadband power grid harmonic tracking and suppression method, characterized in that: The steps include: The adaptive phase-locked loop module is applied to the cascaded biquad generalized integrator to construct an adaptive cascaded biquad generalized integrator phase-locked loop model; The broadband grid voltage is input into an adaptive cascaded dual second-order generalized integrator phase-locked loop model, and the parameters in the adaptive phase-locked loop module are modified based on the fundamental frequency of the broadband grid voltage to obtain a grid adaptive frequency that follows the broadband grid frequency. Based on the grid adaptive frequency, an adaptive cascaded dual second-order generalized integrator phase-locked loop model extracts the orthogonal components and positive and negative sequence components of the harmonic frequencies that vary with the broadband grid frequency from the harmonics of the broadband grid voltage.

2. The broadband power grid harmonic tracking and suppression method according to claim 1, characterized in that: The method of applying the adaptive phase-locked loop module to the cascaded biquad generalized integrator to construct an adaptive cascaded biquad generalized integrator phase-locked loop model specifically includes: Constructing a cascaded biquad generalized integrator, wherein the cascaded biquad generalized integrator comprises at least two biquad generalized integrators connected in parallel; The adaptive phase-locked loop module is applied to the cascaded dual second-order generalized integrator, so that the feedback end of the adaptive phase-locked loop module is connected with the input end of the cascaded dual second-order generalized integrator to form an adaptive cascaded dual second-order generalized integrator phase-locked loop model.

3. The broadband power grid harmonic tracking and suppression method according to claim 2, characterized in that: The cascaded biquad generalized integrator includes a fundamental biquad generalized integrator and at least one harmonic biquad generalized integrator.

4. The broadband power grid harmonic tracking and suppression method according to claim 3 is characterized in that: The method of modifying the parameters in the adaptive phase-locked loop module based on the fundamental frequency of the broadband grid voltage to obtain a grid adaptive frequency that follows the broadband grid frequency changes, specifically includes: Input the broadband grid voltage into the fundamental biquad generalized integrator to obtain the orthogonal signal of the fundamental frequency; The orthogonal signal of the fundamental frequency is fed back to the adaptive phase-locked loop module to modify the parameters of the adaptive phase-locked loop module, so that the adaptive phase-locked loop module outputs a grid adaptive frequency that follows the fundamental frequency.

5. The broadband power grid harmonic tracking and suppression method according to claim 3 is characterized in that: The adaptive cascaded dual second-order generalized integrator phase-locked loop model based on the grid adaptive frequency extracts the orthogonal components and positive and negative sequence components of the harmonic frequency that changes with the broadband grid frequency from the harmonics of the broadband grid voltage; specifically includes: Feeding back the grid adaptive frequency to the fundamental wave biquad generalized integrator to output the positive and negative sequence components of the grid adaptive frequency; The positive and negative sequence components of the grid adaptive frequency are fed back to the harmonic biquad generalized integrator to extract the harmonic orthogonal components and positive and negative sequence components that vary with the wide-band grid frequency.

6. The broadband power grid harmonic tracking and suppression method according to claim 3, characterized in that: Before inputting the wideband grid voltage into the fundamental biquad generalized integrator, the coordinates of the wideband grid voltage need to be converted, that is, the three-phase wideband grid voltage is converted from a three-phase stationary coordinate system to a grid voltage component under a two-phase stationary coordinate system.

7. The broadband power grid harmonic tracking and suppression method according to claim 3, characterized in that: When the harmonic content in the broadband power grid increases, the cascaded biquad generalized integrator includes a plurality of harmonic biquad generalized integrators.

8. The broadband power grid harmonic tracking and suppression method according to claim 7, characterized in that: When the harmonic content in the broadband power grid increases, the operating frequency of the harmonic biquad generalized integrator is set to the grid frequency multiplied by the corresponding harmonic order; k The value is divided by the corresponding harmonic order.

9. The broadband power grid harmonic tracking and suppression method according to claim 2, characterized in that: The output end of each biquad generalized integrator in the cascaded biquad generalized integrator is connected to the positive / negative sequence component calculation module.

10. The broadband power grid harmonic tracking and suppression method according to claim 2, characterized in that: The input end of each biquad generalized integrator in the cascaded biquad generalized integrator is provided with a coordinate conversion module and a harmonic subtraction module, wherein: The coordinate conversion module is used to convert the three-phase broadband power grid voltage from the three-phase stationary coordinate system to the broadband power grid voltage component in the two-phase stationary coordinate system; The forward input end of the harmonic subtraction module is connected to the output end of the coordinate conversion module, the reverse input end of the harmonic subtraction module is connected to the orthogonal component output ends of other biquad generalized integrators except the current biquad generalized integrator; the output end of the harmonic subtraction module is connected to the current biquad generalized integrator.

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