Current control method, device, computer device, storage medium and product

Abstract

The application relates to the technical field of current compensation, in particular to a current control method and device, computer equipment, storage medium and product. The method comprises the following steps: extracting components of three-phase voltage of a to-be-processed grid-connected point to obtain a first negative sequence component in a fundamental wave, a second negative sequence component in a 5th harmonic wave and a positive sequence component in a 7th harmonic wave; compensating current backstepping is carried out according to the first negative sequence component, the second negative sequence component and the positive sequence component to obtain a compensating current corresponding to the to-be-processed grid-connected point; and a reference value obtained by superimposing the compensating current and grid-connected current of the to-be-processed grid-connected point is input to an inverter current inner loop controller to enable the inverter current inner loop controller to carry out current control according to the compensating current. The application realizes current control and current compensation for the grid-connected point, guarantees that the operation efficiency of power distribution equipment and the power utilization quality of users are not affected, and prevents the problem of three-phase voltage imbalance.

Description

Technical Field

[0001] This application relates to the field of current compensation technology, and in particular to a current control method, device, computer equipment, storage medium, and product. Background Technology

[0002] With the continuous development of distributed photovoltaic (PV) systems, their penetration rate in distribution areas continues to increase.

[0003] However, due to the uneven distribution of three-phase loads in residential areas and the high proportion of single-phase photovoltaic grid connection, three-phase voltage imbalance occurs at the grid connection point, affecting the operating efficiency of power distribution equipment and the quality of electricity for users. Summary of the Invention

[0004] Therefore, it is necessary to provide a current control method, device, computer equipment, storage medium, and product that can guarantee the power quality of users in response to the above-mentioned technical problems.

[0005] In a first aspect, this application provides a current control method. The method includes:

[0006] The three-phase voltage at the grid connection point to be processed is extracted to obtain the first negative sequence component in the fundamental wave, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic.

[0007] The compensation current corresponding to the grid connection point to be processed is obtained by back-calculating the compensation current based on the first negative sequence component, the second negative sequence component, and the positive sequence component.

[0008] The reference value obtained by superimposing the compensation current and the grid connection current of the grid connection point to be processed is input to the inverter current inner loop controller so that the inverter current inner loop controller can perform current control according to the compensation current.

[0009] In one embodiment, the component extraction of the three-phase voltage at the grid connection point to be processed to obtain the first negative-sequence component in the fundamental frequency, the second negative-sequence component in the 5th harmonic, and the positive-sequence component in the 7th harmonic includes:

[0010] The three-phase voltage of the grid connection point to be processed is converted into a reference voltage in a two-phase stationary coordinate system;

[0011] The reference voltage is subjected to component extraction to obtain the first negative sequence component in the fundamental frequency, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic.

[0012] In one embodiment, the component extraction of the reference voltage to obtain the first negative-sequence component of the fundamental frequency, the second negative-sequence component of the 5th harmonic, and the positive-sequence component of the 7th harmonic includes:

[0013] Based on the reference voltage, the fundamental signal pair, the 5th harmonic signal pair, and the 7th harmonic signal pair are determined;

[0014] Based on the fundamental wave signal pair, component extraction is performed to obtain the first negative sequence component in the fundamental wave;

[0015] Based on the 5th harmonic signal pair, the second negative sequence component in the 5th harmonic is obtained by component extraction.

[0016] Based on the 7th harmonic signal pair, component extraction is performed to obtain the positive sequence component of the 7th harmonic.

[0017] In one embodiment, the step of back-calculating the compensation current based on the first negative-sequence component, the second negative-sequence component, and the positive-sequence component to obtain the compensation current corresponding to the grid connection point to be processed includes:

[0018] The three-phase unbalance compensation current is determined based on the first negative sequence component;

[0019] The 5th harmonic compensation current is determined based on the second negative sequence component;

[0020] Based on the positive sequence components, determine the 7th harmonic compensation current;

[0021] The compensation current corresponding to the grid connection point to be processed is determined based on the three-phase unbalance compensation current, the 5th harmonic compensation current, and the 7th harmonic compensation current.

[0022] In one embodiment, determining the compensation depth coefficient includes:

[0023] The compensation depth coefficient is determined based on the inverter's rated current, the current active output current amplitude, and the required compensation current amplitude.

[0024] In one embodiment, determining the compensation depth coefficient includes:

[0025] The compensation depth coefficient is determined based on the inverter's rated current, the current active output current amplitude, and the required compensation current amplitude.

[0026] Secondly, this application also provides a current control device. The device includes:

[0027] The extraction module is used to extract the components of the three-phase voltage at the grid connection point to be processed, and obtain the first negative sequence component in the fundamental wave, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic.

[0028] The reverse calculation module is used to reverse calculate the compensation current based on the first negative sequence component, the second negative sequence component and the positive sequence component to obtain the compensation current corresponding to the grid connection point to be processed.

[0029] The control module is used to input the reference value of the superposition of the compensation current and the grid connection current of the grid connection point to be processed to the inverter current inner loop controller, so that the inverter current inner loop controller can perform current control according to the compensation current.

[0030] Thirdly, this application also provides a computer device. The computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to perform the following steps:

[0031] The three-phase voltage at the grid connection point to be processed is extracted to obtain the first negative sequence component in the fundamental wave, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic.

[0032] The compensation current corresponding to the grid connection point to be processed is obtained by back-calculating the compensation current based on the first negative sequence component, the second negative sequence component, and the positive sequence component.

[0033] The reference value obtained by superimposing the compensation current and the grid connection current of the grid connection point to be processed is input to the inverter current inner loop controller so that the inverter current inner loop controller can perform current control according to the compensation current.

[0034] Fourthly, this application also provides a computer-readable storage medium. The computer-readable storage medium stores a computer program thereon, which, when executed by a processor, performs the following steps:

[0035] The three-phase voltage at the grid connection point to be processed is extracted to obtain the first negative sequence component in the fundamental wave, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic.

[0036] The compensation current corresponding to the grid connection point to be processed is obtained by back-calculating the compensation current based on the first negative sequence component, the second negative sequence component, and the positive sequence component.

[0037] The reference value obtained by superimposing the compensation current and the grid connection current of the grid connection point to be processed is input to the inverter current inner loop controller so that the inverter current inner loop controller can perform current control according to the compensation current.

[0038] Fifthly, this application also provides a computer program product. The computer program product includes a computer program that, when executed by a processor, performs the following steps:

[0039] The three-phase voltage at the grid connection point to be processed is extracted to obtain the first negative sequence component in the fundamental wave, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic.

[0040] The compensation current corresponding to the grid connection point to be processed is obtained by back-calculating the compensation current based on the first negative sequence component, the second negative sequence component, and the positive sequence component.

[0041] The reference value obtained by superimposing the compensation current and the grid connection current of the grid connection point to be processed is input to the inverter current inner loop controller so that the inverter current inner loop controller can perform current control according to the compensation current.

[0042] The aforementioned current control method, device, computer equipment, storage medium, and product extract components from the three-phase voltage of the grid connection point to be processed, obtaining the first negative sequence component in the fundamental frequency, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic; based on the first negative sequence component, the second negative sequence component, and the positive sequence component, the compensation current is back-calculated to obtain the compensation current corresponding to the grid connection point to be processed; finally, the reference value obtained by superimposing the compensation current and the grid connection current of the grid connection point to be processed is input to the inverter current inner loop controller, so that the inverter current inner loop controller can perform current control according to the compensation current. As can be seen from the above, when current control is required, the grid connection point voltage can be separated into positive and negative sequences at multiple frequencies to obtain the first negative sequence component in the fundamental frequency, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic. This eliminates spectral leakage between frequencies and provides a data basis for subsequent accurate calculations. Furthermore, by determining the compensation current corresponding to the grid connection point to be processed, current control and current compensation for the grid connection point are achieved, ensuring that the operating efficiency of the power distribution equipment and the power quality of users are not affected, and preventing the problem of three-phase voltage imbalance. Attached Figure Description

[0043] Figure 1 An application environment diagram of a current control method provided in an embodiment of this application;

[0044] Figure 2 A flowchart illustrating the first current control method provided in this application embodiment;

[0045] Figure 3 A schematic flowchart illustrating the second current control method provided in this application embodiment;

[0046] Figure 4 A flowchart illustrating the third current control method provided in this application embodiment;

[0047] Figure 5 A flowchart illustrating the fourth current control method provided in this application embodiment;

[0048] Figure 6 A structural block diagram of a current control device provided in an embodiment of this application;

[0049] Figure 7This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0051] The current control method provided in this application embodiment can be applied to, for example... Figure 1 In the application environment shown, terminal 102 communicates with server 104 via a network. A data storage system can store the data that server 104 needs to process. The data storage system can be integrated onto server 104 or placed on the cloud or other network servers. By extracting components from the three-phase voltage of the grid connection point to be processed, the first negative-sequence component of the fundamental frequency, the second negative-sequence component of the 5th harmonic, and the positive-sequence component of the 7th harmonic are obtained. Based on the first negative-sequence component, the second negative-sequence component, and the positive-sequence component, the compensation current corresponding to the grid connection point to be processed is calculated. Finally, the reference value obtained by superimposing the compensation current and the grid connection current of the grid connection point to be processed is input to the inverter current inner loop controller. Terminal 102 can be, but is not limited to, various personal computers, laptops, smartphones, tablets, IoT devices, and portable wearable devices. IoT devices can be smart speakers, smart TVs, smart air conditioners, smart vehicle devices, etc. Portable wearable devices can be smartwatches, smart bracelets, head-mounted devices, etc. Server 104 can be implemented using a standalone server or a server cluster composed of multiple servers.

[0052] In one embodiment, such as Figure 2 As shown, a current control method is provided, which is applied to... Figure 1 Taking server 104 as an example, the following steps are included:

[0053] S201 extracts the components of the three-phase voltage at the grid connection point to be processed, obtaining the first negative sequence component in the fundamental wave, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic.

[0054] It should be noted that the three-phase voltage at the grid connection point to be processed can be separated into positive and negative sequences at multiple frequencies based on the multiple second-order generalized integrator (MSOGI), so as to obtain the first negative sequence component in the fundamental wave, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic.

[0055] In one embodiment of this application, when it is necessary to extract components from the three-phase voltage of the grid connection point to be processed to obtain the first negative sequence component in the fundamental frequency, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic, the following may be included: converting the three-phase voltage of the grid connection point to be processed into a reference voltage in a two-phase stationary coordinate system; extracting components from the reference voltage to obtain the first negative sequence component in the fundamental frequency, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic.

[0056] S202, the compensation current is back-calculated based on the first negative sequence component, the second negative sequence component and the positive sequence component to obtain the compensation current corresponding to the grid connection point to be processed.

[0057] It should be noted that when it is necessary to back-calculate the compensation current based on the first negative sequence component, the second negative sequence component, and the positive sequence component to obtain the compensation current corresponding to the grid connection point to be processed, the three-phase unbalance compensation current, the 5th harmonic compensation current, and the 7th harmonic compensation current can be determined by back-calculating the compensation current based on the first negative sequence component, the second negative sequence component, and the positive sequence component, respectively. Then, the compensation current corresponding to the grid connection point to be processed can be determined based on the three-phase unbalance compensation current, the 5th harmonic compensation current, and the 7th harmonic compensation current.

[0058] S203 inputs the reference value, which is the sum of the compensation current and the grid connection current of the point to be processed, to the inverter current inner loop controller so that the inverter current inner loop controller can perform current control according to the compensation current.

[0059] In one embodiment of this application, the original grid-connected current of the photovoltaic inverter is... (Generated by the Maximum Power Point Tracking (MPPT) and the DC bus voltage control loop) is superimposed with the aforementioned compensation current to form the final inverter output current reference value, which can be specifically shown below:

[0060] ;

[0061] in, This refers to compensating for the current; This refers to the grid-connected current; This refers to the current reference value.

[0062] The synthesized current reference value is fed into the inverter's inner current loop controller. As an example, a proportional resonant (PR) controller is used instead of a traditional PI controller to achieve zero steady-state error tracking of the fundamental and multiple harmonic currents. The transfer function of the PR controller is:

[0063] ;

[0064] Where Kp is the proportional gain, Krn is the nth resonant gain, ωcn is the bandwidth parameter of the resonant controller, and ω1 is the fundamental angular frequency. This controller has extremely high gain at the fundamental, 5th, and 7th harmonic frequencies, ensuring that the inverter can accurately track composite current commands containing multiple frequency components.

[0065] To further explain, the output of the current inner loop PR controller is essentially a voltage compensation quantity u. PR The physical meaning of this is the voltage deviation that the inverter needs to establish across the LC filter inductor to drive the actual output current to track the reference current. To obtain the complete modulated voltage reference required by the inverter bridge arm, a grid voltage feedforward component also needs to be added, i.e.:

[0066] ;

[0067] Among them, u abc PR This is the output voltage compensation amount for the PR controller, used to eliminate current tracking errors; u abc ff This is the feedforward quantity of the grid connection point voltage, usually taken as the measured voltage V at the grid connection point. abc pcc The value after low-pass filtering.

[0068] The aforementioned current control method extracts components from the three-phase voltage of the grid connection point to obtain the first negative-sequence component of the fundamental frequency, the second negative-sequence component of the 5th harmonic, and the positive-sequence component of the 7th harmonic. Based on these components, a compensation current is derived to obtain the corresponding compensation current for the grid connection point. Finally, the reference value obtained by superimposing the compensation current with the grid connection current of the grid connection point is input to the inverter's inner current loop controller, enabling the controller to perform current control based on the compensation current. As can be seen from the above, when current control is required, the grid connection point voltage can be separated into positive and negative sequences at multiple frequencies to obtain the first negative-sequence component of the fundamental frequency, the second negative-sequence component of the 5th harmonic, and the positive-sequence component of the 7th harmonic. This eliminates spectral leakage between frequencies, providing a data foundation for subsequent accurate calculations. Furthermore, by determining the compensation current corresponding to the grid connection point, current control and compensation for the grid connection point are achieved, ensuring that the operating efficiency of power distribution equipment and the power quality for users are not affected, and preventing three-phase voltage imbalance.

[0069] In one embodiment of this application, such as Figure 3 As shown, when it is necessary to extract components from the three-phase voltage at the grid connection point to obtain the first negative-sequence component of the fundamental frequency, the second negative-sequence component of the 5th harmonic, and the positive-sequence component of the 7th harmonic, the following can be included:

[0070] S301 converts the three-phase voltage of the grid connection point to be processed into a reference voltage in a two-phase stationary coordinate system.

[0071] In one embodiment of this application, the three-phase voltage of the grid connection point to be processed is converted into two-phase stationary coordinate system components by Clarke (Clarke Transformation) to obtain the reference voltage;

[0072] Specifically, ;

[0073] Among them, v α v β Reference voltage; v a v b v c It is a three-phase voltage.

[0074] S302 extracts components from the reference voltage to obtain the first negative sequence component in the fundamental frequency, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic.

[0075] In one embodiment of this application, when it is necessary to extract components from a reference voltage to obtain a first negative-sequence component in the fundamental frequency, a second negative-sequence component in the 5th harmonic, and a positive-sequence component in the 7th harmonic, the following steps may be included: determining a fundamental frequency signal pair, a 5th harmonic signal pair, and a 7th harmonic signal pair based on the reference voltage; performing component extraction based on the fundamental frequency signal pair to obtain the first negative-sequence component in the fundamental frequency; performing component extraction based on the 5th harmonic signal pair to obtain the second negative-sequence component in the 5th harmonic; wherein, performing component extraction based on the 7th harmonic signal pair to obtain the positive-sequence component in the 7th harmonic.

[0076] Specifically, after determining the reference voltage, v can be... α v β The signals are fed into their respective MSOGI (Multiple Second-Order Generalized Integrator) groups for processing. Each MSOGI group outputs in-phase and quadrature signal pairs at each frequency. The fundamental signal pair (v...) 1α ',qv 1α ') and (v 1β ',qv 1β '), 5th harmonic signal pair (v 5α ',qv 5α ') and (v 5β ',qv 5β '), 7th harmonic signal pair (v 7α ',qv 7α ') and (v 7β ',qv 7β ').

[0077] In one embodiment of this application, the fundamental orthogonal signal pairs output by SOGI are used to separate the fundamental positive-sequence and negative-sequence components through a positive-negative-sequence calculation module (PNSC) to obtain the first negative-sequence component in the fundamental. The α and β components of the fundamental positive-sequence and negative-sequence are calculated as follows:

[0078] ;

[0079] ;

[0080] The superscripts “+” and “-” represent the positive and negative order components, respectively.

[0081] In one embodiment of this application, the process of component extraction of the 5th harmonic signal pair is as follows:

[0082] ;

[0083] In one embodiment of this application, the process of component extraction of the 7th harmonic signal pair is as follows:

[0084] .

[0085] The aforementioned current control method converts the three-phase voltage of the grid connection point to be processed into a reference voltage in a two-phase stationary coordinate system. Then, it extracts components from the reference voltage to obtain the first negative-sequence component of the fundamental frequency, the second negative-sequence component of the 5th harmonic, and the positive-sequence component of the 7th harmonic. This provides a data foundation for subsequently determining the compensation current corresponding to the grid connection point to be processed, ensuring the smooth progress of subsequent processes.

[0086] In one embodiment, such as Figure 4 As shown, when it is necessary to back-calculate the compensation current based on the first negative sequence component, the second negative sequence component, and the positive sequence component to obtain the compensation current corresponding to the grid connection point to be processed, the following can be included:

[0087] S401, determine the three-phase unbalanced compensation current based on the first negative sequence component.

[0088] It should be noted that the compensation current to be injected into the power grid is derived by using the equivalent impedance model, so that the voltage drop generated by this current flowing through the line impedance can just offset the original voltage distortion and imbalance.

[0089] Furthermore, let the equivalent impedance of the line between the grid connection point and the common coupling point (PCC) of the transformer substation be Z. l =R l +jX l , where R l and X lThese represent the line resistance and reactance, respectively. For the voltage distortion component ΔV that needs compensation, the required injected compensation current I... comp It should meet the following requirements:

[0090] ;

[0091] After rearranging the above formula, we can obtain:

[0092] .

[0093] In one embodiment of this application, the three-phase unbalance compensation current can be determined according to the calculation formula of the compensation current as follows:

[0094] .

[0095] S402, determine the 5th harmonic compensation current based on the second negative sequence component.

[0096] In one embodiment of this application, at the 5th harmonic frequency, the line impedance needs to be recalculated according to the frequency: Z5=R l +j5X l (Ignoring the frequency change of resistance due to the skin effect), therefore, the 5th harmonic compensation current can be determined according to the calculation formula of the compensation current as follows:

[0097] ;

[0098] S403 determines the 7th harmonic compensation current based on the positive sequence component.

[0099] In one embodiment of this application, at the 7th harmonic frequency, the line impedance is Z7=R. l +j7X l Therefore, based on the calculation formula for the compensation current, the 7th harmonic compensation current can be determined as follows:

[0100] ;

[0101] S404. Based on the three-phase unbalance compensation current, the 5th harmonic compensation current, and the 7th harmonic compensation current, determine the compensation current corresponding to the grid connection point to be processed.

[0102] It should be noted that when it is necessary to determine the compensation current corresponding to the grid connection point to be processed based on the three-phase unbalance compensation current, the 5th harmonic compensation current, and the 7th harmonic compensation current, the following may be included: performing a three-phase natural coordinate system transformation on the three-phase unbalance compensation current, the 5th harmonic compensation current, and the 7th harmonic compensation current to determine the reference value of the three-phase compensation current; determining the compensation depth coefficient; and determining the compensation current corresponding to the grid connection point to be processed based on the compensation depth coefficient and the reference value of the three-phase compensation current.

[0103] Specifically, when it is necessary to determine the reference value of the three-phase compensation current, the three-phase unbalance compensation current, the 5th harmonic compensation current, and the 7th harmonic compensation current can be superimposed, as shown below:

[0104] ;

[0105] Furthermore, the superimposed currents are transformed into a three-phase natural coordinate system to determine the reference values ​​for the three-phase compensation currents:

[0106] ;

[0107] It should be noted that when it is necessary to determine the compensation current corresponding to the grid connection point to be processed based on the compensation depth coefficient and the reference value of the three-phase compensation current, the following formula can be used:

[0108] ;

[0109] To further explain, when it is necessary to determine the compensation depth coefficient, the following can be included: specifically, determine the compensation depth coefficient based on the inverter's rated current, the current active output current amplitude, and the required compensation current amplitude.

[0110] .

[0111] The aforementioned current control method determines the compensation current corresponding to the grid connection point to be processed by using three-phase unbalance compensation current, 5th harmonic compensation current, and 7th harmonic compensation current. This achieves current control and compensation for the grid connection point, ensuring that the operating efficiency of power distribution equipment and the power quality of users are not affected, and preventing the problem of three-phase voltage imbalance.

[0112] In one embodiment, such as Figure 5 As shown, when current control is required, the following may be included:

[0113] S501 converts the three-phase voltage of the grid connection point to be processed into a reference voltage in a two-phase stationary coordinate system.

[0114] S502 determines the fundamental signal pair, the 5th harmonic signal pair, and the 7th harmonic signal pair based on the reference voltage.

[0115] S503 extracts components from the fundamental signal to obtain the first negative sequence component in the fundamental signal.

[0116] S504 extracts components from the 5th harmonic signal to obtain the second negative-order component of the 5th harmonic.

[0117] S505 extracts components from the 7th harmonic signal to obtain the positive sequence component of the 7th harmonic.

[0118] S506, determine the three-phase unbalanced compensation current based on the first negative sequence component.

[0119] S507 determines the 5th harmonic compensation current based on the second negative sequence component.

[0120] S508 determines the 7th harmonic compensation current based on the positive sequence component.

[0121] S509 determines the compensation current corresponding to the grid connection point to be processed based on the three-phase unbalance compensation current, the 5th harmonic compensation current, and the 7th harmonic compensation current.

[0122] S510 inputs the reference value, which is the sum of the compensation current and the grid connection current of the point to be processed, to the inverter current inner loop controller so that the inverter current inner loop controller can perform current control according to the compensation current.

[0123] The aforementioned current control method extracts components from the three-phase voltage of the grid connection point to obtain the first negative-sequence component of the fundamental frequency, the second negative-sequence component of the 5th harmonic, and the positive-sequence component of the 7th harmonic. Based on these components, a compensation current is derived to obtain the corresponding compensation current for the grid connection point. Finally, the reference value obtained by superimposing the compensation current with the grid connection current of the grid connection point is input to the inverter's inner current loop controller, enabling the controller to perform current control based on the compensation current. As can be seen from the above, when current control is required, the grid connection point voltage can be separated into positive and negative sequences at multiple frequencies to obtain the first negative-sequence component of the fundamental frequency, the second negative-sequence component of the 5th harmonic, and the positive-sequence component of the 7th harmonic. This eliminates spectral leakage between frequencies, providing a data foundation for subsequent accurate calculations. Furthermore, by determining the compensation current corresponding to the grid connection point, current control and compensation for the grid connection point are achieved, ensuring that the operating efficiency of power distribution equipment and the power quality for users are not affected, and preventing three-phase voltage imbalance.

[0124] It should be understood that although the steps in the flowcharts of the above embodiments are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0125] Based on the same inventive concept, this application also provides a current control device for implementing the aforementioned current control method. The solution provided by this device is similar to the implementation described in the above method; therefore, the specific limitations in one or more current control device embodiments provided below can be found in the limitations of the current control method described above, and will not be repeated here.

[0126] In one embodiment, such as Figure 6 As shown, a current control device is provided, including: an extraction module 10, a reverse calculation module 20, and a control module 30, wherein:

[0127] Extraction module 10 is used to extract components of the three-phase voltage at the grid connection point to be processed, and obtain the first negative sequence component in the fundamental wave, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic.

[0128] The reverse calculation module 20 is used to reverse calculate the compensation current based on the first negative sequence component, the second negative sequence component and the positive sequence component, so as to obtain the compensation current corresponding to the grid connection point to be processed.

[0129] The control module 30 is used to input the reference value of the superposition of the compensation current and the grid connection current of the grid connection point to be processed to the inverter current inner loop controller, so that the inverter current inner loop controller can perform current control according to the compensation current.

[0130] In one embodiment, the three-phase voltage of the grid connection point to be processed is converted into a reference voltage in a two-phase stationary coordinate system;

[0131] The reference voltage is subjected to component extraction to obtain the first negative sequence component in the fundamental frequency, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic.

[0132] In one embodiment, the fundamental signal pair, the subharmonic signal pair, and the subharmonic signal pair are determined based on a reference voltage;

[0133] Based on the fundamental wave signal, the first negative sequence component in the fundamental wave is obtained by component extraction.

[0134] Based on the subharmonic signal, the second negative sequence component in the subharmonic is obtained by component extraction.

[0135] The positive-sequence component of the subharmonic is obtained by extracting components from the subharmonic signal.

[0136] In one embodiment, the three-phase unbalance compensation current is determined based on the first negative sequence component;

[0137] The 5th harmonic compensation current is determined based on the second negative sequence component.

[0138] The 7th harmonic compensation current is determined based on the positive sequence components.

[0139] Based on the three-phase unbalance compensation current, the 5th harmonic compensation current, and the 7th harmonic compensation current, determine the compensation current corresponding to the grid connection point to be processed.

[0140] In one embodiment, the three-phase unbalance compensation current, subharmonic compensation current and subharmonic compensation current are transformed into a three-phase natural coordinate system to determine the reference value of the three-phase compensation current.

[0141] Determine the compensation depth coefficient;

[0142] Based on the compensation depth coefficient and the reference value of the three-phase compensation current, determine the compensation current corresponding to the grid connection point to be processed.

[0143] In one embodiment, the compensation depth coefficient is determined based on the inverter's rated current, the current active output current amplitude, and the required compensation current amplitude.

[0144] The aforementioned current control device extracts components from the three-phase voltage of the grid connection point to be processed, obtaining the first negative-sequence component of the fundamental frequency, the second negative-sequence component of the 5th harmonic, and the positive-sequence component of the 7th harmonic. Based on these components, a compensation current is derived to obtain the compensation current corresponding to the grid connection point. Finally, the reference value obtained by superimposing the compensation current with the grid connection current of the grid connection point is input to the inverter's inner current loop controller, enabling the controller to perform current control based on the compensation current. As can be seen from the above, when current control is required, the grid connection point voltage can be separated into positive and negative sequences at multiple frequencies to obtain the first negative-sequence component of the fundamental frequency, the second negative-sequence component of the 5th harmonic, and the positive-sequence component of the 7th harmonic. This eliminates spectral leakage between frequencies, providing a data foundation for subsequent accurate calculations. Furthermore, by determining the compensation current corresponding to the grid connection point, current control and compensation for the grid connection point are achieved, ensuring that the operating efficiency of the power distribution equipment and the power quality for users are not affected, and preventing three-phase voltage imbalance.

[0145] Each module in the aforementioned current control device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the operations corresponding to each module.

[0146] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 7As shown, the computer device includes a processor, memory, input / output interface, communication interface, display unit, and input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interface. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The input / output interface is used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC (Near Field Communication), or other technologies. When the computer program is executed by the processor, it implements a current control method. The display unit is used to form a visually visible image and can be a display screen, projection device, or virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the computer device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the casing of the computer device, or external keyboards, touchpads, or mice, etc.

[0147] Those skilled in the art will understand that Figure 7 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0148] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to perform the following steps:

[0149] The three-phase voltage at the grid connection point to be processed is extracted to obtain the first negative sequence component in the fundamental wave, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic.

[0150] The compensation current is calculated by back-calculating the first negative sequence component, the second negative sequence component and the positive sequence component to obtain the compensation current corresponding to the grid connection point to be processed.

[0151] The reference value, which is the sum of the compensation current and the grid connection current of the point to be processed, is input to the inverter current inner loop controller so that the inverter current inner loop controller can perform current control based on the compensation current.

[0152] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0153] The three-phase voltage of the grid connection point to be processed is converted into a reference voltage in a two-phase stationary coordinate system;

[0154] The reference voltage is subjected to component extraction to obtain the first negative sequence component in the fundamental frequency, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic.

[0155] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0156] Based on the reference voltage, determine the fundamental signal pair, the 5th harmonic signal pair, and the 7th harmonic signal pair;

[0157] Based on the fundamental wave signal, the first negative sequence component in the fundamental wave is obtained by component extraction.

[0158] Based on the 5th harmonic signal, the second negative sequence component in the 5th harmonic is obtained by component extraction.

[0159] The positive-sequence component of the 7th harmonic is obtained by extracting components from the 7th harmonic signal.

[0160] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0161] The three-phase unbalance compensation current is determined based on the first negative sequence component.

[0162] The 5th harmonic compensation current is determined based on the second negative sequence component.

[0163] The 7th harmonic compensation current is determined based on the positive sequence components.

[0164] Based on the three-phase unbalance compensation current, the 5th harmonic compensation current, and the 7th harmonic compensation current, determine the compensation current corresponding to the grid connection point to be processed.

[0165] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0166] Three-phase natural coordinate system transformation is performed on the three-phase unbalance compensation current, the 5th harmonic compensation current and the 7th harmonic compensation current to determine the reference value of the three-phase compensation current;

[0167] Determine the compensation depth coefficient;

[0168] Based on the compensation depth coefficient and the reference value of the three-phase compensation current, determine the compensation current corresponding to the grid connection point to be processed.

[0169] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0170] The compensation depth coefficient is determined based on the inverter's rated current, the current active output current amplitude, and the required compensation current amplitude.

[0171] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, the computer program performing the following steps when executed by a processor:

[0172] The three-phase voltage at the grid connection point to be processed is extracted to obtain the first negative sequence component in the fundamental wave, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic.

[0173] The compensation current is calculated by back-calculating the first negative sequence component, the second negative sequence component and the positive sequence component to obtain the compensation current corresponding to the grid connection point to be processed.

[0174] The reference value, which is the sum of the compensation current and the grid connection current of the point to be processed, is input to the inverter current inner loop controller so that the inverter current inner loop controller can perform current control based on the compensation current.

[0175] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0176] The three-phase voltage of the grid connection point to be processed is converted into a reference voltage in a two-phase stationary coordinate system;

[0177] The reference voltage is subjected to component extraction to obtain the first negative sequence component in the fundamental frequency, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic.

[0178] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0179] Based on the reference voltage, determine the fundamental signal pair, the 5th harmonic signal pair, and the 7th harmonic signal pair;

[0180] Based on the fundamental wave signal, the first negative sequence component in the fundamental wave is obtained by component extraction.

[0181] Based on the 5th harmonic signal, the second negative sequence component in the 5th harmonic is obtained by component extraction.

[0182] The positive-sequence component of the 7th harmonic is obtained by extracting components from the 7th harmonic signal.

[0183] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0184] The three-phase unbalance compensation current is determined based on the first negative sequence component.

[0185] The 5th harmonic compensation current is determined based on the second negative sequence component.

[0186] The 7th harmonic compensation current is determined based on the positive sequence components.

[0187] Based on the three-phase unbalance compensation current, the 5th harmonic compensation current, and the 7th harmonic compensation current, determine the compensation current corresponding to the grid connection point to be processed.

[0188] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0189] Three-phase natural coordinate system transformation is performed on the three-phase unbalance compensation current, the 5th harmonic compensation current and the 7th harmonic compensation current to determine the reference value of the three-phase compensation current;

[0190] Determine the compensation depth coefficient;

[0191] Based on the compensation depth coefficient and the reference value of the three-phase compensation current, determine the compensation current corresponding to the grid connection point to be processed.

[0192] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0193] The compensation depth coefficient is determined based on the inverter's rated current, the current active output current amplitude, and the required compensation current amplitude.

[0194] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, performs the following steps:

[0195] The three-phase voltage at the grid connection point to be processed is extracted to obtain the first negative sequence component in the fundamental wave, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic.

[0196] The compensation current is calculated by back-calculating the first negative sequence component, the second negative sequence component and the positive sequence component to obtain the compensation current corresponding to the grid connection point to be processed.

[0197] The reference value, which is the sum of the compensation current and the grid connection current of the point to be processed, is input to the inverter current inner loop controller so that the inverter current inner loop controller can perform current control based on the compensation current.

[0198] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0199] The three-phase voltage of the grid connection point to be processed is converted into a reference voltage in a two-phase stationary coordinate system;

[0200] The reference voltage is subjected to component extraction to obtain the first negative sequence component in the fundamental frequency, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic.

[0201] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0202] Based on the reference voltage, determine the fundamental signal pair, the 5th harmonic signal pair, and the 7th harmonic signal pair;

[0203] Based on the fundamental wave signal, the first negative sequence component in the fundamental wave is obtained by component extraction.

[0204] Based on the 5th harmonic signal, the second negative sequence component in the 5th harmonic is obtained by component extraction.

[0205] The positive-sequence component of the 7th harmonic is obtained by extracting components from the 7th harmonic signal.

[0206] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0207] The three-phase unbalance compensation current is determined based on the first negative sequence component.

[0208] The 5th harmonic compensation current is determined based on the second negative sequence component.

[0209] The 7th harmonic compensation current is determined based on the positive sequence components.

[0210] Based on the three-phase unbalance compensation current, the 5th harmonic compensation current, and the 7th harmonic compensation current, determine the compensation current corresponding to the grid connection point to be processed.

[0211] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0212] Three-phase natural coordinate system transformation is performed on the three-phase unbalance compensation current, the 5th harmonic compensation current and the 7th harmonic compensation current to determine the reference value of the three-phase compensation current;

[0213] Determine the compensation depth coefficient;

[0214] Based on the compensation depth coefficient and the reference value of the three-phase compensation current, determine the compensation current corresponding to the grid connection point to be processed.

[0215] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0216] The compensation depth coefficient is determined based on the inverter's rated current, the current active output current amplitude, and the required compensation current amplitude.

[0217] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of related data must comply with the relevant laws, regulations and standards of the relevant countries and regions.

[0218] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0219] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0220] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A current control method, characterized in that, The method includes: The three-phase voltage at the grid connection point to be processed is extracted to obtain the first negative sequence component in the fundamental wave, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic. The compensation current corresponding to the grid connection point to be processed is obtained by back-calculating the compensation current based on the first negative sequence component, the second negative sequence component, and the positive sequence component. The reference value obtained by superimposing the compensation current and the grid connection current of the grid connection point to be processed is input to the inverter current inner loop controller so that the inverter current inner loop controller can perform current control according to the compensation current.

2. The method according to claim 1, characterized in that, The three-phase voltage of the grid connection point to be processed is extracted to obtain the first negative sequence component in the fundamental frequency, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic, including: The three-phase voltage of the grid connection point to be processed is converted into a reference voltage in a two-phase stationary coordinate system; The reference voltage is subjected to component extraction to obtain the first negative sequence component in the fundamental frequency, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic.

3. The method according to claim 2, characterized in that, The component extraction of the reference voltage to obtain the first negative-sequence component in the fundamental frequency, the second negative-sequence component in the 5th harmonic, and the positive-sequence component in the 7th harmonic includes: Based on the reference voltage, the fundamental signal pair, the 5th harmonic signal pair, and the 7th harmonic signal pair are determined; Based on the fundamental wave signal pair, component extraction is performed to obtain the first negative sequence component in the fundamental wave; Based on the 5th harmonic signal pair, the second negative sequence component in the 5th harmonic is obtained by component extraction. Based on the 7th harmonic signal pair, component extraction is performed to obtain the positive sequence component of the 7th harmonic.

4. The method according to claim 1, characterized in that, The step of back-calculating the compensation current based on the first negative sequence component, the second negative sequence component, and the positive sequence component to obtain the compensation current corresponding to the grid connection point to be processed includes: The three-phase unbalance compensation current is determined based on the first negative sequence component; The 5th harmonic compensation current is determined based on the second negative sequence component; Based on the positive sequence components, determine the 7th harmonic compensation current; The compensation current corresponding to the grid connection point to be processed is determined based on the three-phase unbalance compensation current, the 5th harmonic compensation current, and the 7th harmonic compensation current.

5. The method according to claim 4, characterized in that, The step of determining the compensation current corresponding to the grid connection point to be processed based on the three-phase imbalance compensation current, the 5th harmonic compensation current, and the 7th harmonic compensation current includes: The three-phase unbalanced compensation current, the 5th harmonic compensation current, and the 7th harmonic compensation current are transformed into a three-phase natural coordinate system to determine the reference value of the three-phase compensation current. Determine the compensation depth coefficient; The compensation current corresponding to the grid connection point to be processed is determined based on the compensation depth coefficient and the three-phase compensation current reference value.

6. The method according to claim 5, characterized in that, The determination of the compensation depth coefficient includes: The compensation depth coefficient is determined based on the inverter's rated current, the current active output current amplitude, and the required compensation current amplitude.

7. A current control device, characterized in that, The device includes: The extraction module is used to extract the components of the three-phase voltage at the grid connection point to be processed, and obtain the first negative sequence component in the fundamental wave, the second negative sequence component in the 5th harmonic, and the positive sequence component in the 7th harmonic. The reverse calculation module is used to reverse calculate the compensation current based on the first negative sequence component, the second negative sequence component and the positive sequence component to obtain the compensation current corresponding to the grid connection point to be processed. The control module is used to input the reference value of the superposition of the compensation current and the grid connection current of the grid connection point to be processed to the inverter current inner loop controller, so that the inverter current inner loop controller can perform current control according to the compensation current.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

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