Voltage and current harmonic coordination suppression method and system based on power electronic converter

Abstract

The invention provides a voltage and current harmonic coordinated suppression method and system based on a power electronic converter, the method works in a typical scene of distributed power supply network construction and network-following hybrid control, and the method comprises the following steps: using extracted load current harmonic as a network-following converter harmonic control instruction to suppress load harmonic current; a harmonic virtual impedance method is adopted to adjust the grid-connected harmonic voltage of the grid-forming converter, so that the harmonic content of voltage and current is inhibited in a coordinated manner. According to the method, the equivalent power supply characteristics of network construction and network following are fully utilized, comprehensive treatment of the background harmonic voltage and harmonic current of the power grid is realized, and the network access electric energy quality of the grid-connected system under the weak network is improved.

Description

Technical Field

[0001] The present invention relates to the application field of harmonic suppression in distribution network substations, and in particular to a voltage and current harmonic coordination suppression method and system based on a power electronic converter. Background Art

[0002] With the vigorous promotion and construction of new distribution systems, more and more distributed renewable energy and local loads are connected to the substation through power electronic converters, resulting in an increase in the harmonic content of the grid voltage. In addition, due to the influence of line impedance, the grid voltage waveform at the point of common coupling (PCC) of the renewable energy grid-connected system is seriously distorted. At the same time, the local load in the low-voltage distribution network usually exhibits three-phase imbalance and nonlinear characteristics, resulting in poor quality of the grid-connected system's current, which will not meet the requirements of relevant national standards for the voltage at the PCC point of renewable energy grid-connected and the harmonic distortion rate of the grid-connected grid to be less than 5%. The traditional harmonic suppression method is to achieve passive control through power quality compensation devices such as active power filters (APF), but it will increase the system operation and maintenance costs. Summary of the invention

[0003] In order to solve the problem that the traditional harmonic suppression method in the prior art is to achieve passive governance through power quality compensation devices such as active power filters (APF), but this will increase the system operation and maintenance costs, the present invention proposes a voltage and current harmonic coordination suppression method based on power electronic converters. The method works in a typical scenario of distributed power grid construction and grid hybrid control. The method includes:

[0004] The extracted load current harmonics are used as harmonic control instructions for the grid-following converter to suppress the load harmonic current;

[0005] The harmonic virtual impedance method is used to adjust the grid-connected harmonic voltage of the grid-connected converter, thereby achieving coordinated suppression of the voltage and current harmonic content.

[0006] Optionally, the adopting of the harmonic virtual impedance method to adjust the grid-connected harmonic voltage of the grid-connected converter, thereby achieving coordinated suppression of voltage and current harmonic content includes:

[0007] Based on typical grid conditions, the harmonic virtual impedance is determined using simulation results;

[0008] Based on the grid operation conditions, the harmonic virtual impedance is determined in real time through control methods;

[0009] The grid-connected harmonic voltage of the grid-connected converter is adjusted based on the harmonic virtual impedance.

[0010] Optionally, determining harmonic virtual impedance by a control method based on the operating condition of the power grid includes:

[0011] Based on the acceptable upper limit of each harmonic content, the fundamental voltage content at the grid connection point and the grid-connected harmonic voltage, a control method is used to determine the value of each harmonic virtual impedance;

[0012] Or based on the total harmonic voltage distortion rate and the total harmonic distortion rate of the PCC point voltage specified in the standard, a control method is used to determine the value of the harmonic virtual impedance;

[0013] The control method includes: a negative feedback closed-loop control method.

[0014] Optionally, the control method is used to determine the value of each harmonic virtual impedance based on the acceptable upper limit of each harmonic content, the grid-connected point fundamental voltage content and the grid-connected harmonic voltage, including:

[0015] Determine the reference value of harmonic voltage relative to fundamental content based on the acceptable upper limit of each harmonic content, the harmonic distortion rate of the grid-connected current and the harmonic distortion rate of the grid-connected voltage;

[0016] The value of each harmonic virtual impedance is determined based on the reference value of the harmonic voltage relative to the fundamental content, the fundamental voltage content of the PCC grid-connected point and the grid-connected harmonic voltage.

[0017] Optionally, determining the reference value of the harmonic voltage relative to the fundamental content based on the acceptable upper limit of each harmonic content, the harmonic distortion rate of the grid-connected current, and the harmonic distortion rate of the grid-connected voltage includes:

[0018] Step 1: Detect the harmonic distortion rate of the grid-connected current and the grid-connected voltage. If the harmonic distortion rate of the grid-connected current is greater than the set threshold, proceed to step 2, otherwise proceed to step 1;

[0019] Step 2: Set the hth harmonic voltage relative to the fundamental content reference value as the upper limit of the acceptable content of each harmonic, so that the harmonic current can be suppressed to the greatest extent, and then proceed to step 3;

[0020] Step 3: Detect the harmonic distortion rate of the grid-connected current and the grid-connected voltage. If the harmonic distortion rate of the grid-connected current is greater than the set threshold, it is necessary to add an additional power quality compensation device and proceed to step 5. Otherwise, calculate the sum of the harmonic distortion rates of the grid-connected current and the grid-connected voltage to obtain the sum of the harmonic distortion rates and proceed to step 4.

[0021] Step 4: Determine whether the sum of harmonic distortion rates is greater than the sum of harmonic distortion rates at the previous moment. If so, subtract the set step size from the h-th harmonic voltage relative to the fundamental content reference value as the h-th harmonic voltage relative to the fundamental content reference value, and return to step 3. Otherwise, add the set step size from the h-th harmonic voltage relative to the fundamental content reference value as the h-th harmonic voltage relative to the fundamental content reference value, and return to step 3.

[0022] Step 5: Determine the hth harmonic voltage relative to the fundamental content reference value corresponding to the harmonic distortion rate and the minimum value as the hth harmonic voltage relative to the fundamental content reference value.

[0023] Optionally, the control method is used to determine the value of the harmonic virtual impedance based on the total harmonic voltage distortion rate and the total harmonic distortion rate of the PCC point voltage specified in the standard, including:

[0024] Determine the reference value of the total harmonic voltage distortion rate based on the total harmonic voltage distortion rate, the harmonic distortion rate of the grid-connected current and the harmonic distortion rate of the grid-connected voltage specified in the standard;

[0025] The value of the harmonic virtual impedance is determined based on the total harmonic voltage distortion rate reference value and the total harmonic distortion rate of the PCC point voltage.

[0026] Optionally, determining the reference value of the total harmonic voltage distortion rate based on the total harmonic voltage distortion rate specified in the standard, the harmonic distortion rate of the grid-connected current, and the harmonic distortion rate of the grid-connected voltage includes:

[0027] Step I: Detect the harmonic distortion rate of the grid-connected current and the grid-connected voltage. If the harmonic distortion rate of the grid-connected current is greater than the set threshold, enter step II, otherwise enter step I;

[0028] Step II: Set the reference value of the harmonic distortion rate of the grid-connected current to the standard total harmonic voltage distortion rate, suppress it to the maximum extent, and proceed to step III;

[0029] Step III: Detect the harmonic distortion rate of the grid-connected current and the grid-connected voltage. If the harmonic distortion rate of the grid-connected current is greater than the set threshold, an additional power quality compensation device is added to terminate the operation. Otherwise, the sum of the harmonic distortion rates of the grid-connected current and the grid-connected voltage is calculated to obtain the distortion rate sum, and then enter step IV.

[0030] Step IV: determine whether the sum of the distortion rates is greater than the sum of the distortion rates at the previous moment. If so, subtract the set step length from the reference value of the total harmonic distortion rate of the PCC point voltage as the reference value of the total harmonic distortion rate of the PCC point voltage, return to step III, add the set step length to the reference value of the total harmonic distortion rate of the PCC point voltage as the reference value of the total harmonic distortion rate of the PCC point voltage, and return to step III;

[0031] Step V: Determine the total harmonic distortion rate reference value of the PCC point voltage corresponding to the harmonic distortion rate and the minimum value as the total harmonic distortion rate reference value of the PCC point voltage, and end.

[0032] Optionally, the set threshold value is 5%.

[0033] Optionally, adjusting the grid-connected harmonic voltage of the grid-connected converter based on the harmonic virtual impedance includes:

[0034] Calculate the harmonic virtual impedance and multiply it by the grid-connected harmonic current to get the virtual voltage;

[0035] The adjusted grid-connected harmonic voltage is obtained by subtracting the virtual voltage from the grid-connected harmonic voltage.

[0036] On the other hand, the present invention also provides a voltage and current harmonic coordination suppression system based on a power electronic converter, comprising:

[0037] The grid-following suppression module is used to suppress the load harmonic current by using the extracted load current harmonics as the harmonic control instructions of the grid-following converter in the typical scenario of distributed power grid-following hybrid control;

[0038] The grid suppression module is used to adjust the grid-connected harmonic voltage of the grid-connected converter by using the harmonic virtual impedance method in the typical scenario of distributed power grid-connected hybrid control, thereby achieving coordinated suppression of the voltage and current harmonic content.

[0039] Optionally, the network building suppression module includes:

[0040] The simulation submodule determines the harmonic virtual impedance using simulation results based on typical power grid conditions;

[0041] The dynamic submodule is used for the grid operation condition and determines the harmonic virtual impedance through the control method;

[0042] The regulating submodule regulates the grid-connected harmonic voltage of the grid-connected converter based on the harmonic virtual impedance.

[0043] Optionally, the dynamic submodule includes:

[0044] An accurate calculation unit, used to determine the value of each harmonic virtual impedance by a control method based on the acceptable upper limit of each harmonic content, the grid-connected point fundamental voltage content and the grid-connected harmonic voltage;

[0045] A simplified calculation unit is used to determine the value of harmonic virtual impedance by using a control method based on the total harmonic voltage distortion rate and the total harmonic distortion rate of the PCC point voltage specified in the standard;

[0046] The control method is a negative feedback closed-loop control method.

[0047] Optionally, the precise calculation unit includes:

[0048] The first calculation subunit is used to determine the reference value of the harmonic voltage relative to the fundamental wave content based on the acceptable upper limit of each harmonic content, the harmonic distortion rate of the grid-connected current and the harmonic distortion rate of the grid-connected voltage;

[0049] The second calculation subunit is used to determine the value of each harmonic virtual impedance based on the harmonic voltage relative to the fundamental content reference value, the fundamental voltage content of the PCC grid connection point and the grid-connected harmonic voltage;

[0050] The control method is a negative feedback closed-loop control method.

[0051] Optionally, the first computing subunit is specifically configured to:

[0052] Step 1: Detect the harmonic distortion rate of the grid-connected current and the grid-connected voltage. If the harmonic distortion rate of the grid-connected current is greater than the set threshold, proceed to step 2, otherwise proceed to step 1;

[0053] Step 2: Set the hth harmonic voltage relative to the fundamental content reference value as the upper limit of the acceptable content of each harmonic, so that the harmonic current can be suppressed to the greatest extent, and then proceed to step 3;

[0054] Step 3: Detect the harmonic distortion rate of the grid-connected current and the grid-connected voltage. If the harmonic distortion rate of the grid-connected current is greater than the set threshold, it is necessary to add an additional power quality compensation device and proceed to step 5. Otherwise, calculate the sum of the harmonic distortion rates of the grid-connected current and the grid-connected voltage to obtain the sum of the harmonic distortion rates and proceed to step 4.

[0055] Step 4: Determine whether the sum of harmonic distortion rates is greater than the sum of harmonic distortion rates at the previous moment. If so, subtract the set step size from the h-th harmonic voltage relative to the fundamental content reference value as the h-th harmonic voltage relative to the fundamental content reference value, and return to step 3. Otherwise, add the set step size from the h-th harmonic voltage relative to the fundamental content reference value as the h-th harmonic voltage relative to the fundamental content reference value, and return to step 3.

[0056] Step 5: Determine the hth harmonic voltage relative to the fundamental content reference value corresponding to the harmonic distortion rate and the minimum value as the hth harmonic voltage relative to the fundamental content reference value.

[0057] Optionally, the simplified calculation submodule is specifically used for:

[0058] Determine the reference value of the total harmonic voltage distortion rate based on the total harmonic voltage distortion rate, the harmonic distortion rate of the grid-connected current and the harmonic distortion rate of the grid-connected voltage specified in the standard;

[0059] The value of the harmonic virtual impedance is determined based on the total harmonic voltage distortion rate reference value and the total harmonic distortion rate of the PCC point voltage.

[0060] Optionally, the specific implementation steps of determining the reference value of the total harmonic voltage distortion rate based on the total harmonic voltage distortion rate, the harmonic distortion rate of the grid-connected current and the harmonic distortion rate of the grid-connected voltage specified in the standard in the simplified calculation submodule include:

[0061] Step I: Detect the harmonic distortion rate of the grid-connected current and the grid-connected voltage. If the harmonic distortion rate of the grid-connected current is greater than the set threshold, enter step II, otherwise enter step I;

[0062] Step II: Set the reference value of the harmonic distortion rate of the grid-connected current to the standard total harmonic voltage distortion rate, suppress it to the maximum extent, and proceed to step III;

[0063] Step III: Detect the harmonic distortion rate of the grid-connected current and the grid-connected voltage. If the harmonic distortion rate of the grid-connected current is greater than the set threshold, an additional power quality compensation device is added to terminate the operation. Otherwise, the sum of the harmonic distortion rates of the grid-connected current and the grid-connected voltage is calculated to obtain the distortion rate sum, and then enter step IV.

[0064] Step IV: determine whether the sum of the distortion rates is greater than the sum of the distortion rates at the previous moment. If so, subtract the set step length from the reference value of the total harmonic distortion rate of the PCC point voltage as the reference value of the total harmonic distortion rate of the PCC point voltage, return to step III, add the set step length to the reference value of the total harmonic distortion rate of the PCC point voltage as the reference value of the total harmonic distortion rate of the PCC point voltage, and return to step III;

[0065] Step V: Determine the total harmonic distortion rate reference value of the PCC point voltage corresponding to the harmonic distortion rate and the minimum value as the total harmonic distortion rate reference value of the PCC point voltage, and end.

[0066] Optionally, the set threshold value is 5%.

[0067] Optionally, the regulating submodule is specifically used to:

[0068] Calculate the harmonic virtual impedance and multiply it by the grid-connected harmonic current to get the virtual voltage;

[0069] The adjusted grid-connected harmonic voltage is obtained by subtracting the virtual voltage from the grid-connected harmonic voltage.

[0070] In another aspect, the present application further provides an electronic device, comprising: at least one processor and a memory; the memory and the processor are connected via a bus;

[0071] The memory is used to store one or more programs;

[0072] When the one or more programs are executed by the at least one processor, the voltage and current harmonic coordination suppression method based on the power electronic converter as described above is implemented.

[0073] On the other hand, the present application further provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed, the voltage and current harmonic coordination suppression method based on a power electronic converter as described above is implemented.

[0074] Compared with the prior art, the present invention has the following beneficial effects:

[0075] The present invention provides a method for coordinated suppression of voltage and current harmonics based on a power electronic converter. The method works in a typical scenario of hybrid control of distributed power grid construction and grid following. The method includes: using the extracted load current harmonics as harmonic control instructions for the grid following converter to suppress the load harmonic current; using the harmonic virtual impedance method to adjust the grid-connected harmonic voltage of the grid-connected converter, thereby achieving coordinated suppression of the voltage and current harmonic content. The present invention makes full use of the equivalent power supply characteristics of the grid construction and grid following, realizes the comprehensive management of the background harmonic voltage and harmonic current of the power grid, and improves the grid-connected power quality of the hybrid control type grid-connected system. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 This is a flow chart of a method for coordinated suppression of voltage and current harmonics based on a power electronic converter of the present invention;

[0077] Figure 2 It is a schematic diagram of the structure of a multi-module complex filter of the present invention;

[0078] Figure 3 It is a typical structural schematic diagram of the HCL grid-connected system of the present invention;

[0079] Figure 4 Schematic diagram of an equivalent circuit model of the PLL-GFL of the present invention;

[0080] Figure 5 Schematic diagram of an equivalent circuit model of the VSG-GFM of the present invention;

[0081] Figure 6 It is a schematic diagram of the harmonic equivalent model of the HCL grid-connected system of the present invention;

[0082] Figure 7 It is a principle diagram of the harmonic coordination suppression strategy based on impedance regulation of the present invention;

[0083] Figure 8 It is a schematic diagram of the control structure of the PLL-GFL converter of the present invention;

[0084] Fig. 9It is a schematic diagram of the control structure of the VSG-GFM converter when the virtual impedances of each harmonic are independently adjusted according to the present invention;

[0085] Fig.10 It is a schematic diagram of the h-th harmonic virtual impedance control structure of the present invention;

[0086] Fig.11 The flowchart of the algorithm for selecting the voltage harmonic content reference value of the present invention;

[0087] Fig.12 This is a schematic diagram of the main circuit control structure of the VSG-GFM when the virtual impedances of the harmonics of the present invention are the same;

[0088] Fig.13 It is a schematic diagram of the harmonic virtual impedance control structure of the present invention;

[0089] Fig.14 The flowchart of the algorithm for selecting the voltage harmonic content reference value of the present invention;

[0090] Fig.15 The figure is a schematic diagram of the structure of an electronic device of the present invention. DETAILED DESCRIPTION

[0091] The present invention provides a method for coordinated suppression of voltage and current harmonics based on a power electronic converter. In a typical scenario of distributed power source grid-forming and grid-following hybrid control (HCL), the equivalent power supply characteristics of grid-forming (GFM) and grid-following (GFL) are fully utilized to comprehensively adjust the voltage and current harmonic content and improve the power quality of the grid-connected system.

[0092] In order to better understand the present invention, the content of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0093] Example 1

[0094] A voltage and current harmonic coordination suppression method based on power electronic converter, such as Figure 1 As shown, the method works in a typical scenario of distributed power grid construction and grid hybrid control, and the method includes:

[0095] Step S1: using the extracted load current harmonics as harmonic control instructions for the grid-following converter to suppress the load harmonic current;

[0096] Step S2: The harmonic virtual impedance method is used to adjust the grid-connected harmonic voltage of the grid-connected converter, thereby achieving coordinated suppression of the voltage and current harmonic content.

[0097] The present invention discloses a voltage and current harmonic coordination suppression method based on a power electronic converter, and each step is further introduced below:

[0098] Step S1: using the extracted load current harmonics as the harmonic control instructions of the grid-following converter to suppress the load harmonic current, including:

[0099] This embodiment uses multiple complex coefficient filters (MCCF) to extract harmonic components in voltage and current as reference values ​​for power quality management, changes the PLL-GFL control strategy to enable it to have harmonic current compensation capabilities, and at the same time, cooperates with the VSG-GFM output harmonic impedance reshaping technology to achieve coordinated suppression of power quality problems between grid-connected voltage and grid-connected current.

[0100] Extraction of negative sequence and harmonic components based on MCCF: MCCF is composed of multiple complex band-pass filter (CBF) sub-modules. Taking the extraction of load harmonic current as an example, its control structure is as follows: Figure 2 As shown in the figure, I Labc is the harmonic current component, I Lαβ For I Labc The fundamental current component in the αβ coordinate system is: is the hth harmonic current component, and Represents the positive and negative sequence components of the load fundamental current in the αβ coordinate system, is the component of the load harmonic current in the αβ coordinate system, ω 1 is the fundamental angular frequency, ω h is the hth harmonic angular frequency, ω c is the fundamental cutoff frequency, ω hc is the harmonic cutoff frequency, and s is a complex frequency domain variable.

[0101] Taking compensation of fundamental negative sequence and 5th, 7th, 11th, 13th, 17th harmonic current as an example, MCCF should include CBF +1 CBF -1 CBF -5 CBF +7 CBF -11 CBF +13 CBF +17 There are 7 filter modules in total.

[0102] Before introducing step S2, the coupling characteristics of the grid-connected harmonic voltage and grid-connected harmonic current are analyzed first, and then the voltage and current harmonic coordination suppression strategy is obtained:

[0103] The typical structure of HCL grid-connected system is as follows: Figure 3 As shown in the figure, U s is the grid power supply, U dc is a DC voltage source, L 1 , L 2 is the filter inductor, R C is the damping resistor, C 1 is the filter capacitor, Z g is the line impedance, I s1 ,I s2 are the inverter output currents of GFL and GFM, I 01 ,I 02 are the actual output currents of GFL and GFM, I g is the grid current of HCL, I L is the load current, Load1 is a nonlinear rectifier load, and Load2 is a linear load.

[0104] In order to analyze the coupling characteristics of grid-connected harmonic voltage and grid-connected harmonic current, the equivalent circuit models of PLL-GFL and VSG-GFM are established respectively, and PLL-GFL is equivalent to a controlled current source parallel output impedance Z GFL , VSG-GFM is equivalent to a controlled voltage source with a series output impedance Z GFM ,like Figure 4 and Figure 5 As shown in the figure is an equivalent current source, i o is the port output current, u o is the port voltage, is the equivalent voltage source, G cs (s) is the equivalent current source gain function, G vs (s) is the equivalent voltage source gain transfer function.

[0105] Since the two control strategies are usually mainly aimed at the control of the fundamental frequency, the modulation signal mainly includes the fundamental signal. Therefore, in the harmonic frequency band, the controlled current source can be regarded as an open circuit, the controlled voltage source can be regarded as a short circuit, and both inverters can be equivalent to output impedance. Finally, the harmonic equivalent model of the hybrid control grid-connected system is established as follows: Figure 6 As shown in the figure, U sh is the grid harmonic voltage, U pcch is the grid-connected harmonic voltage, I Lh is the nonlinear load harmonic current, I gh is the grid-connected harmonic current, Z GFL With Z GFM are the equivalent harmonic impedances of PLL-GFL and VSG-GFM, Z gh is the line harmonic impedance.

[0106] according to Figure 6The relationship is as follows:

[0107]

[0108] It can be seen that the existence of nonlinear loads and grid distortion voltage will seriously affect the grid-connected harmonic voltage U pcch And the grid-connected harmonic current I gh The harmonic content of the power supply does not meet the national power quality standard (THD ≤ 5%). pcch with I gh There is a coupling relationship. When the grid harmonic voltage U sh When it is larger, the grid-connected harmonic voltage U pcch And the grid-connected harmonic current I gh Therefore, it is necessary to study the coordinated suppression strategy of grid-connected voltage and grid-connected current harmonics when the background harmonics of the power grid are large, so as to improve the grid-connected power quality of the hybrid control grid-connected system.

[0109] The present invention provides a voltage and current harmonic coordination suppression method based on a power electronic converter. The PLL-GFL uses the load current harmonics extracted by the multi-complex filter (MCCF) as the harmonic control instruction to suppress the load harmonic current. At the same time, by adjusting the impedance of the VSG-GFM in the harmonic frequency band, the comprehensive control of the background harmonic voltage and harmonic current of the power grid is achieved. Figure 8 As shown, where U pcc is the voltage at PCC point, I 1dref is the d-axis reference current of the grid-following converter, I 1qref is the q-axis reference current of the grid-following converter, I s1 is the grid-following converter output current, I 1αβref is the reference current of the grid-following converter in αβ coordinates, I s1αβ is the αβ coordinate output current of the grid-following converter, QPR is the proportional resonant regulator, u m1 For the modulated wave.

[0110] Step S2: using a harmonic virtual impedance method to adjust the grid-connected harmonic voltage of the grid-connected converter, thereby achieving coordinated suppression of voltage and current harmonic content, including:

[0111] Based on the typical working conditions of the power grid, the simulation results are used to determine the harmonic virtual impedance. The typical working conditions of the power grid can be understood as representative working conditions, such as the maximum load operating conditions and the steady-state operating conditions.

[0112] Based on the grid operation conditions, the harmonic virtual impedance is determined in real time through control methods;

[0113] The grid-connected harmonic voltage of the grid-connected converter is adjusted based on the harmonic virtual impedance.

[0114] Step S2 is specific:

[0115] There are generally two methods for determining harmonic virtual impedance:

[0116] 1. Determine harmonic virtual impedance through simulation results. Simulation can only model typical application conditions offline. The virtual impedance is selected by testing the effect of different virtual impedances on power quality regulation. The virtual impedance is then preset in the control of the device. It is a preset fixed value and is simple to implement, but its control effect directly depends on the accuracy of the condition model. At the same time, when the grid condition changes, its governance effect will also be affected to a certain extent.

[0117] 2. Dynamically select harmonic virtual impedance through control methods. This method can dynamically adjust the virtual impedance in real time according to the operation status of the power grid in order to achieve the best governance effect. The implementation process is more complicated than the preset fixed value of the simulation, but its governance effect is not affected by the operation conditions of the power grid. Among them, the control method is a negative feedback closed-loop control method, and the regulator includes but is not limited to: proportional integral control, hysteresis control or repetitive control.

[0118] There are two types of harmonic virtual impedance:

[0119] 2.1. Each frequency can be adjusted independently. If the 2nd harmonic needs to be adjusted, the corresponding 2nd harmonic virtual impedance needs to be adjusted; when adjusting the 2nd, 3rd, and 4th harmonics, the 2nd, 3rd, and 4th harmonic virtual impedances need to be added (a total of three virtual impedances), and so on. The more frequencies are adjusted, the more virtual impedances there are, and the implementation is more complicated.

[0120] 2.2. In order to simplify this process, the nonlinear deviation of the impedance at each frequency can be ignored, and the impedance at all frequencies is considered to be the same, so the virtual impedance at each frequency is approximately the same. At this time, multiple virtual impedances Z under each harmonic can be h The solution simplifies to solving for a single virtual impedance Z.

[0121] In this embodiment, a virtual impedance Z is introduced to realize the output harmonic impedance Z of VSG-GFM. GFM Reshape to achieve the purpose of coordinated suppression between grid-connected voltage and grid-connected current. Here, the reshape of harmonic impedance is achieved by subtracting the grid-connected harmonic current from the grid-connected point harmonic voltage multiplied by the virtual impedance to obtain the grid-connected point harmonic voltage control command for control. This implementation process, from the impedance perspective, is equivalent to adjusting Figure 7 Z GFM , which also corresponds to Z GFM Harmonic impedance reshaping, where U VSG is the equivalent voltage source of the grid converter, I GFL is the equivalent current source of the grid-connected converter. The virtual impedance Z here includes the virtual impedance Z of each harmonich , the specific control structure is as follows Fig. 9 As shown, where U 02 is the grid converter output voltage, I o2 is the grid converter output current, U oαβ2 is the grid converter αβ coordinate output voltage, I oαβ2 is the grid-connected converter output current in αβ coordinates, E m is the potential amplitude in the grid converter, E αβ is the potential in the grid converter αβ coordinates, θ m is the potential phase in the grid converter, U vα is the virtual impedance of the equivalent stator resistance and inductance, α-axis voltage drop, U vβ is the virtual impedance β-axis voltage drop of the equivalent stator resistance reactance, I oα2 is the grid converter α-axis output current, I oβ2 is the β-axis output current of the grid converter, R v is the equivalent stator resistance, L v is the equivalent stator inductance, ω 1 is the power frequency angular frequency, E αβ is the potential in the αβ coordinate of the grid converter, QPR is the proportional resonant control regulator, I gh is the grid harmonic current, Z h is the configured virtual harmonic impedance, u m2 Control the modulated wave for network construction.

[0122] Harmonic virtual impedance Z h The value of directly affects the effect of harmonic coordination control. In the first embodiment, it can be reasonably selected according to the simulation results, and Z can be set in the control algorithm. h Preset to a fixed value in advance. The simulation here can only model typical application conditions offline. The virtual impedance is selected by testing the effect of different virtual impedances on power quality regulation. The virtual impedance is then preset in the control of the device. It is a preset fixed value and is simple to implement, but its control effect directly depends on the accuracy of the condition model. At the same time, when the grid condition changes, its governance effect will also be affected to a certain extent.

[0123] Harmonic virtual impedance Z h It is also possible to dynamically select virtual impedance through control methods. This method can dynamically adjust the damping impedance in real time according to the operation status of the power grid in order to achieve the best governance effect. The implementation process is more complicated than the preset fixed value of the simulation, but its governance effect is not affected by the operation conditions of the power grid. The dynamic control method here is a negative feedback closed-loop control method, and the regulator includes but is not limited to: proportional integral control regulator, hysteresis control regulator or repetitive control regulator.

[0124] This embodiment takes the proportional integral control regulator as an example to introduce:

[0125] By adopting a closed-loop proportional-integral control structure, the virtual impedance Z of each harmonic is realized. h to avoid the fixed Z h It is difficult to adapt to dynamically changing working conditions, such as Fig. 9 and Fig.10 It should be noted that the PI closed-loop control here is just an example, and other control methods such as hysteresis control and repetitive control can also be used. is the reference value of the harmonic voltage of order h relative to the fundamental content, U pcc1 is the fundamental voltage content at the PCC grid connection point, U pcch is the grid-connected harmonic voltage.

[0126] In order to achieve coordinated suppression of voltage and current harmonic content, it is necessary to Make reasonable selection. Specific selection methods are as follows Fig.11 shown.

[0127] First, the harmonic distortion rate THD (I g ), when THD(I g )>5%, the algorithm runs, otherwise it does not run;

[0128] Then, set The value is U pcch_lim (U pcch_lim The upper limit of each harmonic content is acceptable), so that the harmonic current is suppressed to the maximum extent, and THD (I g ) and THD(U pcc ), if THD(I g ) is still greater than 5%, indicating that additional power quality compensation devices are needed to achieve suppression, and the algorithm ends. g )≤5%, indicating that the harmonic components of the grid-connected current are effectively suppressed, and the distortion rate and x=THD(I g )+THD(U pcc ), where THD(U pcc ) is the total harmonic distortion rate of the PCC point voltage. The algorithm continues to run. In the figure, k represents the step size of iterative polling, and x k It represents the sum of the voltage distortion rate of the grid connection point and the current distortion rate of the grid at the current moment;

[0129] Next, according to THD (I g ) to continuously adjust the hth harmonic voltage relative to the fundamental content reference value The value of The change step size d is used to continuously search for the optimal value, and finally the output makes the distortion rate and x take the minimum value The selected algorithm can be executed periodically according to actual needs, without the need for real-time execution. g ) is determined by judging whether the sum of the harmonic distortion rates is greater than the sum of the harmonic distortion rates at the previous moment.

[0130] In this embodiment, each frequency can be adjusted independently. If the 2nd harmonic needs to be adjusted, the corresponding 2nd harmonic virtual impedance needs to be adjusted. When adjusting the 2nd, 3rd, and 4th harmonics, the 2nd, 3rd, and 4th harmonic virtual impedances need to be added (a total of three virtual impedances). The more frequencies are adjusted, the more virtual impedances there are, and the implementation is more complicated.

[0131] In another embodiment, in order to simplify this process, it is considered to independently adjust the virtual impedance Z of each harmonic h To reduce the difficulty of implementation, the nonlinear deviation of impedance at each frequency can be ignored, and it is assumed that the impedance at all frequencies is the same, so the virtual impedance at each frequency is approximately the same. At this time, multiple virtual impedances Z under each harmonic can be h The solution is simplified to solving a single harmonic virtual impedance Z. At this time, the control structure of VSG-GFM is as follows: Fig.12 shown.

[0132] The value of the harmonic virtual impedance Z directly affects the effect of harmonic coordination and control. In the first embodiment, a reasonable choice can be made based on the simulation results, and Z can be preset in advance as a fixed value in the control algorithm.

[0133] A single harmonic virtual impedance Z can also be flexibly set to each harmonic impedance Z by adopting a negative feedback closed-loop control structure to avoid the difficulty of fixed Z in adapting to dynamically changing working conditions. Fig.13 It should be noted that the PI closed-loop control here is just an example, and other control methods such as hysteresis control and repetitive control can also be used. In the figure, THD (U pcc )* is the reference value of total harmonic distortion rate of PCC point voltage.

[0134] In order to achieve coordinated suppression of voltage and current harmonic content, it is necessary to set the reference value of total harmonic distortion rate THD (U pcc )* Make reasonable selection. Specific selection methods are as follows Fig.14 shown.

[0135] First, the harmonic distortion rate THD (I g ), when THD(I g )>5%, the algorithm runs, otherwise it does not run;

[0136] Then, set THD(U pcc )* is set to 5 (the total harmonic voltage distortion rate of the 0.38kV system in the national standard is ≤5%), so that the harmonic current is suppressed to the greatest extent, and the THD (I g ) and THD(U pcc ), if THD(I g ) is still greater than 5%, indicating that additional power quality compensation devices are needed to achieve suppression, and the algorithm ends. g )≤5%, indicating that the harmonic components of the grid-connected current are effectively suppressed, and the distortion rate and x=THD(I g )+THD(U pcc ), the algorithm continues to run;

[0137] Next, according to THD (I g ) to continuously adjust the THD(U pcc )* value, by setting THD(U pcc )* changes the step size d to continuously find the optimal value,

[0138] Finally, the output is THD (U pcc )*.THD(U pcc )*The selected algorithm can be executed periodically according to actual needs, without the need for real-time execution.

[0139] Example 2

[0140] The present invention based on the same inventive concept also provides a voltage and current harmonic coordination suppression system based on a power electronic converter, comprising:

[0141] The grid-following suppression module is used to suppress the load harmonic current by using the extracted load current harmonics as the harmonic control instructions of the grid-following converter in the typical scenario of distributed power grid-following hybrid control;

[0142] The grid suppression module is used to adjust the grid-connected harmonic voltage of the grid-connected converter by using the harmonic virtual impedance method in the typical scenario of distributed power grid-connected hybrid control, thereby achieving coordinated suppression of the voltage and current harmonic content.

[0143] Optionally, the method further includes a virtual impedance determination module, comprising:

[0144] A simulation submodule determines harmonic virtual impedance based on simulation results of typical grid operating conditions;

[0145] The dynamic submodule determines the harmonic virtual impedance in real time through a control method based on the grid operation conditions;

[0146] The grid-connected harmonic voltage of the grid-connected converter is adjusted based on the harmonic virtual impedance.

[0147] Optionally, the dynamic submodule includes:

[0148] An accurate calculation unit, used to determine the value of each harmonic virtual impedance by a control method based on the acceptable upper limit of each harmonic content, the grid-connected point fundamental voltage content and the grid-connected harmonic voltage;

[0149] A simplified calculation unit is used to determine the value of harmonic virtual impedance by using a control method based on the total harmonic voltage distortion rate and the total harmonic distortion rate of the PCC point voltage specified in the standard;

[0150] The control method is a closed-loop negative feedback control method, and the regulator includes but is not limited to: proportional integral control, hysteresis control, and repetitive control.

[0151] Optionally, the precise calculation unit includes:

[0152] The first calculation subunit is used to determine the value of each harmonic virtual impedance by a control method based on the acceptable upper limit of each harmonic content, the grid-connected point fundamental voltage content and the grid-connected harmonic voltage;

[0153] The second calculation subunit is used to determine the value of the harmonic virtual impedance by using a control method based on the total harmonic voltage distortion rate and the total harmonic distortion rate of the PCC point voltage specified in the standard;

[0154] The control method is a closed-loop negative feedback control method, and the regulator includes but is not limited to: proportional integral control, hysteresis control, and repetitive control.

[0155] Optionally, the first computing subunit is specifically configured to:

[0156] Step 1: Detect the harmonic distortion rate of the grid-connected current and the grid-connected voltage. If the harmonic distortion rate of the grid-connected current is greater than the set threshold, proceed to step 2, otherwise proceed to step 1;

[0157] Step 2: Set the hth harmonic voltage relative to the fundamental content reference value as the upper limit of the acceptable content of each harmonic, so that the harmonic current can be suppressed to the greatest extent, and then proceed to step 3;

[0158] Step 3: Detect the harmonic distortion rate of the grid-connected current and the grid-connected voltage. If the harmonic distortion rate of the grid-connected current is greater than the set threshold, it is necessary to add an additional power quality compensation device and proceed to step 5. Otherwise, calculate the sum of the harmonic distortion rates of the grid-connected current and the grid-connected voltage to obtain the sum of the harmonic distortion rates and proceed to step 4.

[0159] Step 4: Determine whether the sum of harmonic distortion rates is greater than the sum of harmonic distortion rates at the previous moment. If so, subtract the set step size from the h-th harmonic voltage relative to the fundamental content reference value as the h-th harmonic voltage relative to the fundamental content reference value, and return to step 3. Otherwise, add the set step size from the h-th harmonic voltage relative to the fundamental content reference value as the h-th harmonic voltage relative to the fundamental content reference value, and return to step 3.

[0160] Step 5: Determine the hth harmonic voltage relative to the fundamental content reference value corresponding to the harmonic distortion rate and the minimum value as the hth harmonic voltage relative to the fundamental content reference value.

[0161] Optionally, the simplified calculation submodule is specifically used for:

[0162] Determine the reference value of the total harmonic voltage distortion rate based on the total harmonic voltage distortion rate, the harmonic distortion rate of the grid-connected current and the harmonic distortion rate of the grid-connected voltage specified in the standard;

[0163] The value of the harmonic virtual impedance is determined based on the total harmonic voltage distortion rate reference value and the total harmonic distortion rate of the PCC point voltage.

[0164] Optionally, the specific implementation steps of determining the reference value of the total harmonic voltage distortion rate based on the total harmonic voltage distortion rate, the harmonic distortion rate of the grid-connected current and the harmonic distortion rate of the grid-connected voltage specified by the standard in the second calculation subunit include:

[0165] Step I: Detect the harmonic distortion rate of the grid-connected current and the grid-connected voltage. If the harmonic distortion rate of the grid-connected current is greater than the set threshold, enter step II, otherwise enter step I;

[0166] Step II: Set the reference value of the harmonic distortion rate of the grid-connected current to the standard total harmonic voltage distortion rate, suppress it to the maximum extent, and proceed to step III;

[0167] Step III: Detect the harmonic distortion rate of the grid-connected current and the grid-connected voltage. If the harmonic distortion rate of the grid-connected current is greater than the set threshold, an additional power quality compensation device is added to terminate the operation. Otherwise, the sum of the harmonic distortion rates of the grid-connected current and the grid-connected voltage is calculated to obtain the distortion rate sum, and then enter step IV.

[0168] Step IV: determine whether the sum of the distortion rates is greater than the sum of the distortion rates at the previous moment. If so, subtract the set step length from the reference value of the total harmonic distortion rate of the PCC point voltage as the reference value of the total harmonic distortion rate of the PCC point voltage, return to step III, add the set step length to the reference value of the total harmonic distortion rate of the PCC point voltage as the reference value of the total harmonic distortion rate of the PCC point voltage, and return to step III;

[0169] Step V: Determine the total harmonic distortion rate reference value of the PCC point voltage corresponding to the harmonic distortion rate and the minimum value as the total harmonic distortion rate reference value of the PCC point voltage, and end.

[0170] Optionally, the set threshold value is 5%.

[0171] Optionally, the regulating submodule is specifically used to:

[0172] Calculate the harmonic virtual impedance and multiply it by the grid-connected harmonic current to get the virtual voltage;

[0173] The adjusted grid-connected harmonic voltage is obtained by subtracting the virtual voltage from the grid-connected harmonic voltage.

[0174] Example 3

[0175] like Fig.15 As shown, the present invention also provides an electronic device, which may be a computer device, a single-chip device, an intelligent mobile device, etc. The electronic device in this embodiment may include a processor, a memory, a transceiver component, etc. The memory, the processor, and the transceiver component are connected via a bus; the memory may be used to store an execution program, and an exemplary execution program may include instructions; the processor is used to execute the instructions stored in the memory. The memory may also be used to store data, which may be called and / or modified when the instructions are executed.

[0176] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in a storage medium to implement the corresponding method flow or corresponding functions, so as to implement the steps of a voltage and current harmonic coordination suppression method based on a power electronic converter in the above-mentioned embodiment.

[0177] Example 4

[0178] Based on the same inventive concept, the present invention also provides a readable storage medium, specifically an electronic device readable storage medium (Memory), which is a memory device in the electronic device for storing programs and data. It can be understood that the storage medium here can include both the built-in storage medium in the electronic device and the extended storage medium supported by the electronic device. The storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and these instructions can be one or more execution programs (including program codes). It should be noted that the storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor loads and executes one or more instructions stored in the storage medium, which can implement the steps of a voltage and current harmonic coordination suppression method based on a power electronic converter in the above embodiment.

[0179] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0180] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0181] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1A function specified in one or more boxes.

[0182] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0183] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A voltage and current harmonic coordination suppression method based on a power electronic converter, characterized in that: The method works in a typical scenario of distributed power grid construction and grid hybrid control, and the method includes: The extracted load current harmonics are used as harmonic control instructions for the grid-following converter to suppress the load harmonic current; The harmonic virtual impedance method is used to adjust the grid-connected harmonic voltage of the grid-connected converter, thereby achieving coordinated suppression of the voltage and current harmonic content.

2. The method according to claim 1, characterized in that The harmonic virtual impedance method is used to adjust the grid-connected harmonic voltage of the grid-connected converter, thereby achieving coordinated suppression of the voltage and current harmonic content, including: Based on typical grid conditions, the harmonic virtual impedance is determined using simulation results; Based on the grid operation conditions, the harmonic virtual impedance is determined in real time through control methods; The grid-connected harmonic voltage of the grid-connected converter is adjusted based on the harmonic virtual impedance.

3. The method according to claim 2, characterized in that The method of determining harmonic virtual impedance in real time by a control method based on the operating condition of the power grid includes: Based on the acceptable upper limit of each harmonic content, the fundamental voltage content at the grid connection point and the grid-connected harmonic voltage, a control method is used to determine the value of each harmonic virtual impedance; Or based on the total harmonic voltage distortion rate and the total harmonic distortion rate of the PCC point voltage specified in the standard, a control method is used to determine the value of the harmonic virtual impedance; The control method includes: a negative feedback closed-loop control method.

4. The method according to claim 3, characterized in that The control method is used to determine the value of each harmonic virtual impedance based on the acceptable upper limit of each harmonic content, the grid-connected point fundamental voltage content and the grid-connected harmonic voltage, including: Determine the reference value of harmonic voltage relative to fundamental content based on the acceptable upper limit of each harmonic content, the harmonic distortion rate of the grid-connected current and the harmonic distortion rate of the grid-connected voltage; The value of each harmonic virtual impedance is determined based on the reference value of the harmonic voltage relative to the fundamental content, the fundamental voltage content of the PCC grid-connected point and the grid-connected harmonic voltage.

5. The method according to claim 4, characterized in that The method of determining the reference value of the harmonic voltage relative to the fundamental wave content based on the acceptable upper limit of each harmonic content, the harmonic distortion rate of the grid-connected current and the harmonic distortion rate of the grid-connected voltage includes: Step 1: Detect the harmonic distortion rate of the grid-connected current and the grid-connected voltage. If the harmonic distortion rate of the grid-connected current is greater than the set threshold, proceed to step 2, otherwise proceed to step 1; Step 2: Set the hth harmonic voltage relative to the fundamental content reference value as the upper limit of the acceptable content of each harmonic, so that the harmonic current can be suppressed to the greatest extent, and then proceed to step 3; Step 3: Detect the harmonic distortion rate of the grid-connected current and the grid-connected voltage. If the harmonic distortion rate of the grid-connected current is greater than the set threshold, it is necessary to add an additional power quality compensation device and proceed to step 5. Otherwise, calculate the sum of the harmonic distortion rates of the grid-connected current and the grid-connected voltage to obtain the sum of the harmonic distortion rates and proceed to step 4. Step 4: Determine whether the sum of harmonic distortion rates is greater than the sum of harmonic distortion rates at the previous moment. If so, subtract the set step size from the h-th harmonic voltage relative to the fundamental content reference value as the h-th harmonic voltage relative to the fundamental content reference value, and return to step 3. Otherwise, add the set step size from the h-th harmonic voltage relative to the fundamental content reference value as the h-th harmonic voltage relative to the fundamental content reference value, and return to step 3. Step 5: Determine the hth harmonic voltage relative to the fundamental content reference value corresponding to the harmonic distortion rate and the minimum value as the hth harmonic voltage relative to the fundamental content reference value.

6. The method according to claim 3, characterized in that The control method is used to determine the value of the harmonic virtual impedance based on the total harmonic voltage distortion rate and the total harmonic distortion rate of the PCC point voltage specified in the standard, including: Determine the reference value of the total harmonic voltage distortion rate based on the total harmonic voltage distortion rate, the harmonic distortion rate of the grid-connected current and the harmonic distortion rate of the grid-connected voltage specified in the standard; The value of the harmonic virtual impedance is determined based on the total harmonic voltage distortion rate reference value and the total harmonic distortion rate of the PCC point voltage.

7. The method according to claim 6, characterized in that The determining of the reference value of the total harmonic voltage distortion rate based on the total harmonic voltage distortion rate specified in the standard, the harmonic distortion rate of the grid-connected current and the harmonic distortion rate of the grid-connected voltage includes: Step I: Detect the harmonic distortion rate of the grid-connected current and the grid-connected voltage. If the harmonic distortion rate of the grid-connected current is greater than the set threshold, enter step II, otherwise enter step I; Step II: Set the reference value of the harmonic distortion rate of the grid-connected current to the standard total harmonic voltage distortion rate, suppress it to the maximum extent, and proceed to step III; Step III: Detect the harmonic distortion rate of the grid-connected current and the grid-connected voltage. If the harmonic distortion rate of the grid-connected current is greater than the set threshold, an additional power quality compensation device is added to terminate the operation. Otherwise, the sum of the harmonic distortion rates of the grid-connected current and the grid-connected voltage is calculated to obtain the distortion rate sum, and then enter step IV. Step IV: determine whether the sum of the distortion rates is greater than the sum of the distortion rates at the previous moment. If so, subtract the set step length from the reference value of the total harmonic distortion rate of the PCC point voltage as the reference value of the total harmonic distortion rate of the PCC point voltage, return to step III, add the set step length to the reference value of the total harmonic distortion rate of the PCC point voltage as the reference value of the total harmonic distortion rate of the PCC point voltage, and return to step III; Step V: Determine the total harmonic distortion rate reference value of the PCC point voltage corresponding to the harmonic distortion rate and the minimum value as the total harmonic distortion rate reference value of the PCC point voltage, and end.

8. The method according to any one of claims 5 or 7, characterized in that: The set threshold value is 5%.

9. The method according to claim 2, characterized in that The method of adjusting the grid-connected harmonic voltage of the grid-connected converter based on the harmonic virtual impedance includes: Calculate the harmonic virtual impedance and multiply it by the grid-connected harmonic current to get the virtual voltage; The adjusted grid-connected harmonic voltage is obtained by subtracting the virtual voltage from the grid-connected harmonic voltage.

10. A voltage and current harmonic coordination suppression system based on power electronic converter, characterized in that: include: The grid-following suppression module is used to suppress the load harmonic current by using the extracted load current harmonics as the harmonic control instructions of the grid-following converter in the typical scenario of distributed power grid-following hybrid control; The grid suppression module is used to adjust the grid-connected harmonic voltage of the grid-connected converter by using the harmonic virtual impedance method in the typical scenario of distributed power grid-connected hybrid control, thereby achieving coordinated suppression of the voltage and current harmonic content.

11. The system according to claim 10, characterized in that The network construction suppression module includes a virtual impedance determination module, including: The simulation submodule determines the harmonic virtual impedance using simulation results based on typical grid operating conditions; The dynamic submodule determines the harmonic virtual impedance in real time through control methods based on the grid operation conditions; The regulating submodule regulates the grid-connected harmonic voltage of the grid-connected converter based on the harmonic virtual impedance.

12. The system according to claim 11, characterized in that The dynamic submodule includes: The accurate calculation submodule is used to determine the value of each harmonic virtual impedance by using a control method based on the acceptable upper limit of each harmonic content, the grid-connected point fundamental voltage content and the grid-connected harmonic voltage; A simplified calculation submodule is used to determine the value of harmonic virtual impedance by using a control method based on the total harmonic voltage distortion rate and the total harmonic distortion rate of the PCC point voltage specified in the standard; The control method includes: a negative feedback closed-loop control method.

13. An electronic device, characterized in that: include: at least one processor and memory; The memory and the processor are connected via a bus; The memory is used to store one or more programs; When the one or more programs are executed by the at least one processor, a voltage and current harmonic coordination suppression method based on a power electronic converter as claimed in any one of claims 1 to 9 is implemented.

14. A readable storage medium, characterized in that: An execution program is stored thereon, and when the execution program is executed, a voltage and current harmonic coordination suppression method based on a power electronic converter as described in any one of claims 1 to 9 is implemented.

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