Converter adaptive harmonic suppression method and system under complex background harmonic scenario

Abstract

The present application belongs to the field of harmonic processing, and provides a converter adaptive harmonic suppression method and system under a complex background harmonic scene, which compensates for the grid modulation voltage by using a method for voltage source type background harmonics, quickly identifies the background harmonics in the grid-connected current based on a method for current source type background harmonics, quickly identifies the optimal compensation phase and optimal compensation amplitude of the harmonic component exceeding the threshold, and compensates for the converter current reference instruction. The present application realizes efficient management of power quality problems in the complex scene of comprehensive voltage source type and current source type background harmonics.

Description

Technical Field

[0001] This invention belongs to the field of harmonic suppression, specifically relating to an adaptive harmonic suppression method and system for converters in complex background harmonic scenarios. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Unlike traditional power generation resources that achieve energy conversion through synchronous generators, new energy sources, such as wind power and photovoltaics, use converters as a medium to achieve AC / DC power conversion based on sinusoidal pulse width modulation (SPWM). Due to the non-ideal characteristics of the modulation stage, this process injects harmonic pollution into the power grid, reducing the grid's ability to maintain a standard power frequency sinusoidal waveform and resulting in voltage-source background harmonics. Furthermore, the presence of numerous nonlinear loads on the load side, such as household loads and electric vehicle charging stations, also contributes to current-source background harmonics. In summary, this complex background harmonic scenario degrades power quality, increases line losses, and raises the risk of equipment burnout.

[0004] Traditional harmonic suppression algorithms actively suppress background harmonics by adjusting the equivalent impedance of the converter. However, different background harmonic scenarios require different impedance amplitudes. For voltage-source background harmonics, the virtual impedance needs to be increased to enhance the damping effect, while for current-source background harmonics, the virtual impedance needs to be decreased to avoid their impact on external devices. Therefore, in complex scenarios where both voltage-source and current-source background harmonics coexist, traditional virtual impedance algorithms face a dilemma. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes an adaptive harmonic suppression method and system for converters in complex background harmonic scenarios. This invention achieves efficient management of power quality issues in complex scenarios involving both voltage source and current source background harmonics.

[0006] According to some embodiments, the present invention adopts the following technical solution: An adaptive harmonic suppression method for converters in complex background harmonic scenarios, targeting current source type background harmonics, includes the following steps: Calculate the typical harmonic content in the grid-connected current at the point of common coupling and compare it with a given threshold. If the typical harmonic content is less than or equal to the given threshold, the adaptive harmonic suppression process is not entered. Otherwise, the optimal compensation phase of the harmonic current is obtained based on the hill-climbing algorithm, and then the optimal compensation amplitude of the harmonic current is calculated. The harmonic current signal with the optimal compensation phase and the optimal compensation amplitude is injected into the converter control command signal to achieve adaptive harmonic suppression of current source background harmonics.

[0007] As an alternative implementation, the process of calculating the typical harmonic content in the grid-connected current at the point of common coupling includes: generating a set of discrete time series containing multiple data points based on the current sampling frequency; generating multiple sets of orthogonal discrete triangular signal sequences based on the discrete time series; extracting discrete sequences containing several data points from the current sampling data; and performing convolution and mean filtering operations on each sequence to obtain the harmonic content of each harmonic in the grid-connected current of the converter.

[0008] As a further defined implementation, the process of calculating and generating a discrete-time series containing multiple data points based on the current sampling frequency includes:

[0009] In the formula, T dis Represents a set of discrete time series. N This represents the number of data points in the discrete time series. f sam Indicates the sampling frequency of the signal. f 0 represents the fundamental frequency of the grid voltage; The process of generating multiple sets of orthogonal discrete triangular signal sequences based on the discrete time series includes:

[0010] In the formula, s h Represents a set of discrete sinusoidal sequences. c h Represents a set of discrete cosine sequences. f h Indicates harmonic frequency, subscript h Indicates the harmonic order.

[0011] As a further defined implementation, the process of performing convolution and mean filtering operations on each sequence to obtain the harmonic content of the converter grid-connected current includes:

[0012] In the formula, I h The amplitude of the h-th harmonic current is represented by s. h (n) and c h (n) represents the nth number in the sine discrete sequence and the cosine discrete sequence, respectively. dis (n)c ) represents the nth digit in the discrete sequence obtained from current sampling. c Number, k Indicates the sampling calculation coefficients. N Representing discrete time series T dis Number of data points N s This indicates the number of data points extracted from the current sampling data.

[0013] As an alternative implementation method, the process of obtaining the optimal compensation phase of harmonic current based on the hill-climbing algorithm includes: pre-setting the harmonic current compensation amplitude; determining the initial harmonic current compensation phase according to different optimization steps; generating a harmonic current compensation signal by combining the harmonic current compensation amplitude and the initial harmonic current compensation phase; injecting the harmonic current compensation signal into the grid-connected converter current reference command; comparing the magnitude of each harmonic content under the two initial harmonic current compensation phases to determine the direction of the optimization step size change; executing the optimization iteration process until the termination iteration condition is met; and recording the harmonic current compensation phase at the latest iteration number as the optimal harmonic current compensation phase.

[0014] As a further defined implementation, the process of generating a harmonic current compensation signal by combining the harmonic current compensation amplitude and the initial harmonic current compensation phase, and injecting the harmonic current compensation signal into the grid-connected converter current reference command includes: The initial harmonic current compensation phase is:

[0015] In the formula, the subscript m represents the number of optimization steps. step phase Indicates the phase optimization step size; The harmonic current compensation signal is:

[0016] In the formula, t Indicates time, h Indicates the harmonic order. f 0 represents the fundamental frequency of the grid voltage;

[0017] In the formula, i ref This is the original current reference command for the GFL converter. i refm 'This is the current reference command after the injection of harmonic current signal.'

[0018] As a further defined implementation, the process of comparing the magnitudes of each harmonic content under two initial harmonic current compensation phases to determine the transformation direction of the optimization step size includes: Comparison of harmonic content under two initial harmonic current compensation phases I h The magnitude of is used to determine the transformation direction of the optimization step size. If m=1, then... I h If the value is relatively small, then the following optimization iteration is performed:

[0019] It is a reverse optimization algorithm used for scenarios where the optimal harmonic current compensation phase is between -180 and 0 degrees. P chm This represents the harmonic current compensation phase at the m-th iteration, where the subscript m indicates the optimization step number. step phase Indicates the phase optimization step size; If m=2 I h If the value is relatively small, then the following optimization iteration is performed:

[0020] It is a forward optimization algorithm used for scenarios where the optimal harmonic current compensation phase is between 0 and 180 degrees.

[0021] As a further defined implementation, the process of performing an optimization iteration until the termination iteration condition is met includes: comparing and judging the harmonic content after the m-th and m+1-th compensations. I h The size, if the value after the m-th iteration I h Less than the result of the (m+1)th iteration I h Terminate the iteration process and record the value at the m-th iteration. P chm As the optimal harmonic current compensation phase P ch , P chm This represents the harmonic current compensation phase at the m-th iteration.

[0022] As an alternative implementation, the process of injecting a harmonic current signal with optimal compensation phase and optimal compensation amplitude into the converter control command signal includes: The compensation amplitude of the harmonic current is optimized through iterative optimization, i.e.:

[0023] The subscript m indicates the number of optimization steps. step amp This indicates the step size for amplitude optimization. I chmThis represents the harmonic current compensation amplitude at the m-th iteration; Calculate the harmonic current compensation signal:

[0024] t Indicates time, h Indicates the harmonic order. f 0 represents the fundamental frequency of the grid voltage. P ch Indicates the optimal compensation phase for harmonic current; Compare and judge the compensation after the m-th and m+1-th times. I h The size, if the value after the m-th iteration I h Less than the result of the (m+1)th iteration I h Terminate the iteration process and record the value at the m-th iteration. I chm As the optimal harmonic current compensation amplitude I ch Conversely, continue the iterative process; comprehensive P ch and I ch Obtain the optimal harmonic current compensation signal:

[0025] In the formula, i ch This is the optimal harmonic current compensation signal.

[0026] An adaptive harmonic suppression system for converters in complex background harmonic scenarios, targeting current source-type background harmonics, includes: The trigger module is configured to calculate the typical harmonic content in the grid-connected current at the point of common coupling and compare it with a given threshold. If the typical harmonic content is less than or equal to the given threshold, the adaptive harmonic suppression module is not invoked; otherwise, the adaptive harmonic suppression module is invoked. The adaptive harmonic suppression module is configured to obtain the optimal compensation phase of the harmonic current based on the hill-climbing algorithm, and then calculate the optimal compensation amplitude of the harmonic current. The harmonic current signal with the optimal compensation phase and the optimal compensation amplitude is injected into the converter control command signal to achieve adaptive harmonic suppression of current source background harmonics.

[0027] An adaptive harmonic suppression method for converters in complex background harmonic scenarios, targeting voltage source type background harmonics, includes the following steps: By adding a multi-proportional resonant controller between the current feedback signal and the voltage modulation signal, the compensation amount of the voltage modulation signal is calculated based on the transfer function of the multi-proportional resonant controller and the current feedback signal. The modulation voltage is then corrected based on the compensation amount, thereby achieving active suppression of voltage source background harmonics.

[0028] As an alternative implementation, the process of calculating the compensation amount of the voltage modulation signal based on the transfer function of the multi-proportional resonant controller and the current feedback signal, and correcting the modulation voltage based on the compensation amount, includes: The transfer function of the multi-proportional resonant controller is:

[0029] In the formula, K p The resonant peak of the multi-proportional resonant controller is selected based on the phase margin of the control system, and ζ is the damping ratio, selected according to the actual engineering requirements. ω n The angular velocity of the fundamental voltage wave of the power grid; Compensation amount U MC for:

[0030]

[0031] In the formula, I feed For current feedback signal, U M To compensate for the voltage modulation signal of the pre-converter. U M 'This is the voltage modulation signal for the compensated converter.'

[0032] An adaptive harmonic suppression system for converters in complex background harmonic scenarios, targeting voltage source background harmonics, includes: A multi-ratio resonant controller is positioned between the current feedback signal and the voltage modulation signal; The active suppression module is configured to calculate the compensation amount of the voltage modulation signal based on the transfer function of the multi-proportional resonant controller and the current feedback signal, and to correct the modulation voltage based on the compensation amount, thereby achieving active suppression of voltage source background harmonics.

[0033] An adaptive harmonic suppression method for converters in complex background harmonic scenarios includes the two methods mentioned above. The method compensates for grid modulation voltage using a method targeting voltage source background harmonics, and suppresses background harmonics in the grid-connected current using a method targeting current source background harmonics. I h Perform rapid identification, and identify those exceeding the threshold.I thr The harmonic components, and the optimal compensation phase for these harmonic components. P ch With the optimal compensation amplitude I ch Perform rapid identification of the converter current reference command. i ref Compensation will be provided.

[0034] An adaptive harmonic suppression system for converters in complex background harmonic scenarios includes the two systems mentioned above.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention enables effective management of power quality in complex background harmonic scenarios and has strong adaptability and versatility in new power system scenarios with high proportions of new energy and high proportions of electronic components.

[0036] The harmonic suppression algorithm employed in this invention identifies the optimal compensation amplitude and phase based on the optimization concept, exhibiting high robustness and strong anti-interference capability for different governance scenarios. Furthermore, it requires no additional passive components, effectively improving the distortion of grid-connected current waveforms under complex and distorted power grids solely through the converter algorithm level, demonstrating significant economic advantages and providing strong support for improving power management in distribution systems under new power system scenarios.

[0037] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0038] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0039] Figure 1 This is a flowchart of the adaptive harmonic suppression algorithm for GFL converters targeting current source background harmonics in Embodiment 1 of the present invention.

[0040] Figure 2 This is a flowchart of the adaptive harmonic suppression algorithm for GFL converters in complex background harmonic scenarios, as described in Embodiment 2 of the present invention.

[0041] Figure 3 This describes the relationship between Embodiment 1 and Embodiment 2 of the present invention.

[0042] Figure 4 This is a schematic diagram of the GFL converter adaptive harmonic suppression algorithm topology in a complex background harmonic scenario according to Embodiment 2 of the present invention. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0044] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0045] It should be noted that the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of methods and systems according to various embodiments of this disclosure. It should be noted that each block in a flowchart or block diagram may represent a module, segment, or portion of code, which may include one or more executable instructions for implementing the logical functions specified in the various embodiments. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than that shown in the drawings. For example, two consecutively represented blocks may actually be executed substantially in parallel, or they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the flowcharts and / or block diagrams, and combinations of blocks in the flowcharts and / or block diagrams, may be implemented using a dedicated hardware-based system that performs the specified functions or operations, or using a combination of dedicated hardware and computer instructions.

[0046] Example 1 like Figure 1 As shown, this embodiment provides an adaptive harmonic suppression algorithm for GFL converters targeting current-source background harmonics. This embodiment uses the application of this method to a server as an example for illustration. It is understood that this method can also be applied to terminals, and can also be applied to systems including terminals, servers, and other components, and implemented through interaction between the terminal and the server. The server can be a standalone physical server, a server cluster or distributed system composed of multiple physical servers, or a cloud server providing basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network servers, cloud communication, middleware services, domain name services, CDN security services, and big data and artificial intelligence platforms. The terminal can be a smartphone, tablet, laptop, desktop computer, etc., but is not limited to these. The terminal and server can be directly or indirectly connected via wired or wireless communication, which is not limited herein. In this embodiment, the method includes the following steps: Step 1: Obtain the harmonic components in the grid-connected current by processing the data at the point of common coupling. I h ;like Ih Greater than a given threshold I thr If so, the subsequent adaptive harmonic suppression algorithm will be executed.

[0047] Step 2: Obtain the optimal compensation phase of harmonic current based on hill-climbing algorithm P ch .

[0048] Step 3: Obtain the optimal compensation amplitude of harmonic current based on hill climbing algorithm I ch The optimal compensation harmonic current signal is injected into the converter control command signal to achieve adaptive harmonic suppression of current source background harmonics.

[0049] In some embodiments, the implementation steps of step 1 (obtaining the harmonic components in the grid-connected current) include: (1) Based on the current sampling frequency f sam Calculate and generate a set of discrete time series containing N data points. T dis As shown in equation (1).

[0050] (1) In the formula, T dis Represents a set of discrete time series. N This represents the number of data points in the discrete time series. f sam This indicates the sampling frequency of the signal. f 0 represents the fundamental frequency of the grid voltage.

[0051] (2) Based on T dis generate N h The orthogonal discrete triangular signal sequence is shown in Equation (2), which is used to calculate the harmonic content of the converter grid-connected current.

[0052] (2) In the formula, s h Represents a set of discrete sinusoidal sequences. c h Represents a set of discrete cosine sequences. f h Indicates harmonic frequency, subscript h This indicates the harmonic order, typically ranging from 3 to 20.

[0053] (3) Then extract the data containing current sampling data. N sDiscrete sequence of data points S dis , N s The calculation method is shown in equation (3).

[0054] (3) In the formula, N s This indicates the number of data points extracted from the current sampling data. k This represents the sampling calculation coefficient, which is a positive integer. The larger the value, the stronger the algorithm's anti-interference ability; the smaller the value, the better the algorithm's dynamic response performance. It should be selected according to the actual engineering needs, and is generally selected as 5.

[0055] (4) Furthermore, s h , c h , S dis Perform convolution, mean filtering, and other operations to obtain the harmonic content of the converter grid-connected current. I h As shown in equation (4).

[0056] (4) In the formula, I h The amplitude of the h-th harmonic current is represented by s. h (n) and c h (n) represents the nth number in the sine discrete sequence and the cosine discrete sequence, respectively. dis (n) c ) represents the nth digit in the discrete sequence obtained from current sampling. c Number. k Indicates the sampling calculation coefficients. N Representing discrete time series T dis Number of data points N s This indicates the number of data points extracted from the current sampling data.

[0057] (5) Finally, I h With a given threshold I thr In comparison, when I h Greater than I thr When the time comes, the adaptive harmonic suppression algorithm is activated.

[0058] In some embodiments, the implementation steps of step 2 (obtaining the optimal compensation phase of the harmonic current) include: (1) Given a harmonic current compensation amplitude I ch0 Two initial harmonic current compensation phases are selected. P chm As shown in equation (5).

[0059] (5) In the formula, the subscript m represents the number of optimization steps. step phase This represents the phase optimization step size. The larger the step size, the fewer steps are required for optimization; the smaller the step size, the higher the optimization accuracy.

[0060] (2) Combination I ch0 and P chn The harmonic current compensation signal is generated as shown in Equation (6), and then the harmonic current compensation signal is injected into the GFL converter current reference command as shown in Equation (7).

[0061] (6) In the formula, t Indicates time, h Indicates the harmonic order. f 0 represents the fundamental frequency of the grid voltage.

[0062] (7) In the formula, i ref This is the original current reference command for the GFL converter. i refm 'This is the current reference command after the injection of harmonic current signal.'

[0063] (3) Then compare the two initial harmonic current compensation phases. I h The magnitude of is used to determine the transformation direction of the optimization step size. If m=1, then... I h If the value is small, then perform the optimization iteration as shown in equation (8). If m=2 I h If the value is small, then perform optimization iteration as shown in equation (9).

[0064] (8) Equation 8 shows the reverse optimization algorithm, which is used for scenarios where the optimal harmonic current compensation phase is between -180 and 0 degrees. P chm This represents the harmonic current compensation phase at the m-th iteration.

[0065] (9) Equation 9 shows the forward optimization algorithm, which is used for scenarios where the optimal harmonic current compensation phase is between 0 and 180 degrees.

[0066] (4) Compare and judge the compensation after the mth and (m+1)th times. I h The size, if the value after the m-th iteration I h Less than the result of the (m+1)th iteration I h Terminate the iteration process and record the value at the m-th iteration. P chm As the optimal harmonic current compensation phase P ch Conversely, if the result is not satisfactory, the iterative process continues.

[0067] In some embodiments, the implementation steps of step 3 (achieving adaptive harmonic suppression of current source background harmonics) include: (1) First, the compensation amplitude of the harmonic current is optimized and iterated as shown in (10).

[0068] (10) In the formula, the subscript m represents the number of optimization steps. step amp This represents the step size for amplitude optimization. The larger the step size, the fewer steps are required for optimization; the smaller the step size, the higher the optimization accuracy. I chm This represents the harmonic current compensation amplitude at the m-th iteration.

[0069] (2) Then, substitute into equation (11) to calculate the harmonic current compensation signal, and compare and judge the compensation after the mth and (m+1)th harmonics. I h The size, if the value after the m-th iteration I h Less than the result of the (m+1)th iteration I h Terminate the iteration process and record the value at the m-th iteration. I chm As the optimal harmonic current compensation amplitude I ch Conversely, if the result is not satisfactory, the iterative process continues.

[0070] (11) In the formula, t Indicates time, h Indicates the harmonic order. f 0 represents the fundamental frequency of the grid voltage. P chThis indicates the optimal compensation phase for harmonic currents.

[0071] (3) Comprehensive P ch and I ch The optimal harmonic current compensation signal is obtained as shown in Equation (12), and it is injected into the GFL converter current reference command to realize adaptive harmonic suppression of current source background harmonics.

[0072] (12) In the formula, i ch This is the optimal harmonic current compensation signal.

[0073] Example 2 like Figure 2 As shown, this embodiment provides an adaptive harmonic suppression algorithm for GFL converters in complex background harmonic scenarios. Based on Embodiment 1, the adaptive harmonic suppression algorithm for GFL converters is extended from scenarios with a single current source type background harmonic to complex scenarios that simultaneously include voltage source type and current source type background harmonics. In this embodiment, the method includes the following steps: Step 1: By adding a multi-proportional resonant controller between the current feedback signal and the voltage modulation signal, and adjusting the control parameters of the multi-proportional resonant controller according to the phase margin of the control system, active suppression of voltage source background harmonics is achieved.

[0074] Step 2: Combining the two suppression algorithms mentioned above, which target current-source background harmonics and voltage-source background harmonics respectively, to achieve adaptive harmonic suppression of GFL converters in complex background harmonic scenarios.

[0075] In some embodiments, the implementation steps of step 1 (completing the active suppression of voltage source background harmonics) include: (1) First, according to the multi-proportional resonant controller transfer function G shown in equation (13), PR ( s ), combined with current feedback signal I feed Calculate the compensation amount of the voltage modulation signal. U MC As shown in equation (14).

[0076] (13) In the formula, K pThe resonant peak of the multi-proportional resonant controller is ζ. A larger value indicates stronger suppression of voltage source harmonics, but it may decrease the system's stability under small disturbances. ζ is generally selected based on the phase margin of the control system. ζ is the damping ratio, selected according to the specific engineering requirements. ω n This is the angular velocity of the fundamental voltage of the power grid (typically about 314.15 rad / s).

[0077] (14) (2) Furthermore, in combination U MC The modulation voltage is modified as shown in equation (15). This achieves active suppression of voltage source background harmonics.

[0078] (15) In the formula, U M To compensate for the voltage modulation signal of the previous GFL converter, U M 'This is the voltage modulation signal for the compensated GFL converter.'

[0079] In some embodiments, step 2 (implementing adaptive harmonic suppression of GFL converters in complex background harmonic scenarios) includes the following steps: (1) First, select a suitable multi-proportional resonant controller and modulate the grid voltage based on equations (14) and (15). U M Compensation is performed, and then, based on equation (4), the background harmonics in the grid-connected current are... I h Perform rapid identification, and identify those exceeding the threshold. I thr The harmonic components, based on the optimal compensation phase of equations (8)-(10) for the harmonic components. P ch With the optimal compensation amplitude I ch After rapid identification, the current reference command for the converter is finally substituted into equations (7) and (12). i ref Compensation is performed to proactively improve power quality in complex background harmonic scenarios.

[0080] The relationship between Examples 1 and 2 is as follows: Figure 3 As shown, Embodiment 2 is based on Embodiment 1, and further supplements the virtual impedance algorithm, thereby expanding the application scenarios.

[0081] The schematic diagram of the control structure used in Example 2 is shown below. Figure 4 As shown, by respectively...i ref and U M Compensation is performed to proactively improve the power quality of the power grid under complex background harmonic scenarios.

[0082] Example 3 An adaptive harmonic suppression method for converters in complex background harmonic scenarios, targeting voltage source type background harmonics, includes the following steps: By adding a multi-proportional resonant controller between the current feedback signal and the voltage modulation signal, the compensation amount of the voltage modulation signal is calculated based on the transfer function of the multi-proportional resonant controller and the current feedback signal. The modulation voltage is then corrected based on the compensation amount, thereby achieving active suppression of voltage source background harmonics.

[0083] The process of calculating the compensation amount of the voltage modulation signal based on the transfer function of the multi-proportional resonant controller and the current feedback signal, and then correcting the modulation voltage based on the compensation amount, includes: The transfer function of the multi-proportional resonant controller is:

[0084] In the formula, K p The resonant peak of the multi-proportional resonant controller is selected based on the phase margin of the control system, and ζ is the damping ratio, selected according to the actual engineering requirements. ω n The angular velocity of the fundamental voltage wave of the power grid; Compensation amount U MC for:

[0085]

[0086] In the formula, I feed For current feedback signal, U M To compensate for the voltage modulation signal of the pre-converter. U M 'This is the voltage modulation signal for the compensated converter.'

[0087] Example 4 An adaptive harmonic suppression system for converters in complex background harmonic scenarios, targeting current source-type background harmonics, includes: The trigger module is configured to calculate the typical harmonic content in the grid-connected current at the point of common coupling, compare it with a given threshold, and if the typical harmonic content is less than or equal to the given threshold, recalculate the typical harmonic content and compare it again; otherwise, call the adaptive harmonic suppression module. The adaptive harmonic suppression module is configured to obtain the optimal compensation phase of the harmonic current based on the hill-climbing algorithm, and then calculate the optimal compensation amplitude of the harmonic current. The harmonic current signal with the optimal compensation phase and the optimal compensation amplitude is injected into the converter control command signal to achieve adaptive harmonic suppression of current source background harmonics.

[0088] Example 5 An adaptive harmonic suppression system for converters in complex background harmonic scenarios, targeting voltage source background harmonics, includes: A multi-ratio resonant controller is positioned between the current feedback signal and the voltage modulation signal; The active suppression module is configured to calculate the compensation amount of the voltage modulation signal based on the transfer function of the multi-proportional resonant controller and the current feedback signal, and to correct the modulation voltage based on the compensation amount, thereby achieving active suppression of voltage source background harmonics.

[0089] Example 6 An adaptive harmonic suppression system for converters in complex background harmonic scenarios includes: A multi-ratio resonant controller is positioned between the current feedback signal and the voltage modulation signal; The active suppression module is configured to calculate the compensation amount of the voltage modulation signal based on the transfer function of the multi-proportional resonant controller and the current feedback signal, and to correct the modulation voltage based on the compensation amount, thereby achieving active suppression of voltage source background harmonics. The trigger module is configured to calculate the typical harmonic content in the grid-connected current at the point of common coupling, compare it with a given threshold, and if the typical harmonic content is less than or equal to the given threshold, recalculate the typical harmonic content and compare it again; otherwise, call the adaptive harmonic suppression module. The adaptive harmonic suppression module is configured to obtain the optimal compensation phase of the harmonic current based on the hill-climbing algorithm, and then calculate the optimal compensation amplitude of the harmonic current. The harmonic current signal with the optimal compensation phase and the optimal compensation amplitude is injected into the converter control command signal to achieve adaptive harmonic suppression of current source background harmonics.

[0090] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of hardware embodiments, software embodiments, or embodiments combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0091] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0092] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0093] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0094] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0095] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An adaptive harmonic suppression method for converters under complex background harmonic scenarios, specifically targeting current source type background harmonics, characterized in that... Includes the following steps: Calculate the typical harmonic content in the grid-connected current at the point of common coupling and compare it with a given threshold. If the typical harmonic content is less than or equal to the given threshold, the adaptive harmonic suppression process is not entered. Otherwise, the optimal compensation phase of the harmonic current is obtained based on the hill-climbing algorithm, and then the optimal compensation amplitude of the harmonic current is calculated. The harmonic current signal with the optimal compensation phase and the optimal compensation amplitude is injected into the converter control command signal to achieve adaptive harmonic suppression of current source background harmonics.

2. The adaptive harmonic suppression method for converters in complex background harmonic scenarios as described in claim 1, characterized in that, The process of obtaining the optimal harmonic current compensation phase based on the hill-climbing algorithm includes: pre-setting the harmonic current compensation amplitude; determining the initial harmonic current compensation phase according to different optimization steps; generating a harmonic current compensation signal by combining the harmonic current compensation amplitude and the initial harmonic current compensation phase; injecting the harmonic current compensation signal into the grid-connected converter current reference command; comparing the magnitude of each harmonic content under the two initial harmonic current compensation phases to determine the direction of the optimization step size change; executing the optimization iteration process until the termination iteration condition is met; and recording the harmonic current compensation phase at the latest iteration number as the optimal harmonic current compensation phase.

3. The adaptive harmonic suppression method for converters in complex background harmonic scenarios as described in claim 2, characterized in that, The process of comparing the magnitudes of each harmonic content under two initial harmonic current compensation phases to determine the transformation direction of the optimization step size includes: Comparison of harmonic content under two initial harmonic current compensation phases I h The magnitude of is used to determine the transformation direction of the optimization step size. If m=1, then... I h If the value is relatively small, then the following optimization iteration is performed: It is a reverse optimization algorithm used for scenarios where the optimal harmonic current compensation phase is between -180 and 0 degrees. P chm This represents the harmonic current compensation phase at the m-th iteration, where the subscript m indicates the optimization step number. step phase Indicates the phase optimization step size; If m=2 I h If the value is relatively small, then the following optimization iteration is performed: It is a forward optimization algorithm used for scenarios where the optimal harmonic current compensation phase is between 0 and 180 degrees.

4. The adaptive harmonic suppression method for converters in complex background harmonic scenarios as described in claim 1, characterized in that, The process of injecting a harmonic current signal with optimal compensation phase and optimal compensation amplitude into the converter control command signal includes: The compensation amplitude of the harmonic current is optimized through iterative optimization, i.e.: The subscript m indicates the number of optimization steps. step amp This indicates the step size for amplitude optimization. I chm This represents the harmonic current compensation amplitude at the m-th iteration; Calculate the harmonic current compensation signal: t Indicates time, h Indicates the harmonic order. f 0 represents the fundamental frequency of the grid voltage. P ch Indicates the optimal compensation phase for harmonic current; Compare and judge the compensation after the m-th and m+1-th times. I h The size, if the value after the m-th iteration I h Less than the result of the (m+1)th iteration I h Terminate the iteration process and record the value at the m-th iteration. I chm As the optimal harmonic current compensation amplitude I ch Conversely, continue the iterative process; comprehensive P ch and I ch Obtain the optimal harmonic current compensation signal: In the formula, i ch This is the optimal harmonic current compensation signal.

5. An adaptive harmonic suppression system for converters in complex background harmonic scenarios, specifically targeting current source-type background harmonics, characterized in that... include: The trigger module is configured to calculate the typical harmonic content in the grid-connected current at the point of common coupling and compare it with a given threshold. If the typical harmonic content is less than or equal to the given threshold, the adaptive harmonic suppression module is not invoked; otherwise, the adaptive harmonic suppression module is invoked. The adaptive harmonic suppression module is configured to obtain the optimal compensation phase of the harmonic current based on the hill-climbing algorithm, and then calculate the optimal compensation amplitude of the harmonic current. The harmonic current signal with the optimal compensation phase and the optimal compensation amplitude is injected into the converter control command signal to achieve adaptive harmonic suppression of current source background harmonics.

6. An adaptive harmonic suppression method for converters under complex background harmonic scenarios, specifically targeting voltage source type background harmonics, characterized in that... Includes the following steps: By adding a multi-proportional resonant controller between the current feedback signal and the voltage modulation signal, the compensation amount of the voltage modulation signal is calculated based on the transfer function of the multi-proportional resonant controller and the current feedback signal. The modulation voltage is then corrected based on the compensation amount, thereby achieving active suppression of voltage source background harmonics.

7. The adaptive harmonic suppression method for converters in complex background harmonic scenarios as described in claim 6, characterized in that, The process of calculating the compensation amount of the voltage modulation signal based on the transfer function of the multi-proportional resonant controller and the current feedback signal, and then correcting the modulation voltage based on the compensation amount, includes: The transfer function of the multi-proportional resonant controller is: In the formula, K p The resonant peak of the multi-proportional resonant controller is selected based on the phase margin of the control system, and ζ is the damping ratio, selected according to the actual engineering requirements. ω n The angular velocity of the fundamental voltage wave of the power grid; Compensation amount U MC for: In the formula, I feed For current feedback signal, U M To compensate for the voltage modulation signal of the pre-converter. U M 'This is the voltage modulation signal for the compensated converter.' 8. An adaptive harmonic suppression system for converters in complex background harmonic scenarios, targeting voltage source type background harmonics, characterized by comprising: A multi-ratio resonant controller is positioned between the current feedback signal and the voltage modulation signal; The active suppression module is configured to calculate the compensation amount of the voltage modulation signal based on the transfer function of the multi-proportional resonant controller and the current feedback signal, and to correct the modulation voltage based on the compensation amount, thereby achieving active suppression of voltage source background harmonics.

9. An adaptive harmonic suppression method for converters under complex background harmonic scenarios, characterized in that, Including the methods described in claims 1-5 and claims 7 and 8, the method described in claims 7 and 8 is used to compensate for the modulated voltage of the power grid, and the method described in claims 1-5 is used to reduce background harmonics in the grid-connected current. I h Perform rapid identification, and identify those exceeding the threshold. I thr The harmonic components, and the optimal compensation phase for these harmonic components. P ch With the optimal compensation amplitude I ch Perform rapid identification of the converter current reference command. i ref Compensation will be provided.

10. An adaptive harmonic suppression system for converters under complex background harmonic scenarios, characterized in that it includes: A multi-ratio resonant controller is positioned between the current feedback signal and the voltage modulation signal; The active suppression module is configured to calculate the compensation amount of the voltage modulation signal based on the transfer function of the multi-proportional resonant controller and the current feedback signal, and to correct the modulation voltage based on the compensation amount, thereby achieving active suppression of voltage source background harmonics. The trigger module is configured to calculate the typical harmonic content in the grid-connected current at the point of common coupling and compare it with a given threshold. If the typical harmonic content is less than or equal to the given threshold, the adaptive harmonic suppression module is not invoked; otherwise, the adaptive harmonic suppression module is invoked. The adaptive harmonic suppression module is configured to obtain the optimal compensation phase of the harmonic current based on the hill-climbing algorithm, and then calculate the optimal compensation amplitude of the harmonic current. The harmonic current signal with the optimal compensation phase and the optimal compensation amplitude is injected into the converter control command signal to achieve adaptive harmonic suppression of current source background harmonics.

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