A voltage source converter cross-coupling feedforward compensation method and system

Abstract

The present invention discloses a voltage source converter cross-coupling feedforward compensation method and system thereof, comprising: obtaining a three-phase voltage d Axis components and q axis component; inputting and into the cross-coupled feedforward compensation controller after determining the parameters, outputting the feedforward compensation voltages and; respectively superimposing and with the original control output voltages and respectively and transmitting them to the valve control system; wherein, at least a compensator and a filter are included; by determining the parameters to eliminate the high-frequency negative damping effect of the voltage source converter or to make the high-frequency impedance angle or high-frequency equivalent resistance of the voltage source converter within the required range, the system includes: a sampling module and a cross-coupled feedforward compensation controller.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a voltage source converter cross-coupling feedforward compensation method and a system thereof. Background Art

[0002] Voltage source converters have been widely used in flexible DC transmission, new energy power generation and grid connection, microgrids and energy storage systems, power quality management, rail transit, ship propulsion, industrial transmission, mine systems and other fields, and have great development potential. However, voltage source converters use digital control systems, which have inherent link delays, resulting in high-frequency negative damping effects in the frequency range above 300Hz, especially for modular multi-level converters used in the field of flexible DC transmission. The link delay can be as high as hundreds of microseconds, which is very easy to induce high-frequency oscillations. If high-frequency oscillations are not effectively suppressed, it is easy to cause system shutdown and even breakdown of primary equipment, which seriously threatens the safe and stable operation of the system.

[0003] To this end, existing studies have proposed many suppression strategies for high-frequency oscillations, mainly including passive damping and additional control. Among them, since passive damping devices have the cost of increasing active power loss and reactive power compensation, increasing floor space, etc., resulting in higher investment costs, most of the existing high-frequency oscillation suppression strategies are carried out from the aspect of additional control, specifically including additional active damping control and voltage feedforward filtering. Additional active damping control selects a suitable damping controller to feed back the sampled voltage or current to the control system to suppress high-frequency oscillations, including virtual parallel impedance, virtual series impedance and other suppression strategies. This method selects reasonable damping controller parameters to reduce the high-frequency negative damping frequency range of the voltage source converter, but cannot completely eliminate the high-frequency negative damping. Voltage feedforward filtering is achieved by inserting different types of filters in the voltage feedforward path, including low-pass filters, band-pass filters, band-stop filters, and nonlinear filters. This method can change or weaken the impact of link delay, and then shift the high-frequency negative damping frequency range, but it also cannot completely eliminate the high-frequency negative damping. In summary, the existing high-frequency oscillation suppression strategies can suppress high-frequency oscillations to a certain extent, but most of them are difficult to completely eliminate high-frequency negative damping, and high-frequency oscillations cannot be fundamentally solved. Once the grid conditions change, the above suppression strategies may lose their due effect, and therefore cannot adapt to different grid conditions. Summary of the invention

[0004] In view of this, the present invention provides a voltage source converter cross-coupling feedforward compensation method and system thereof, which are used to at least solve the problem that the high-frequency oscillation suppression strategy in the prior art is difficult to adapt to various grid conditions.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A voltage source converter cross-coupling feedforward compensation method comprises the following steps:

[0007] Get three-phase voltage d Axis Component and q Axis Component ;

[0008] Will and Input to the parameterized cross-coupled feedforward compensation controller , Output feedforward compensation voltage and ;

[0009] Will and Respectively with the original control output voltage and The corresponding superposition is then delivered to the valve control system;

[0010] in, At least the compensator and filter , compensator The constraint condition is to make the high-frequency impedance of the voltage source converter inductive, that is, the high-frequency simplified positive sequence impedance of the voltage source converter is equal to , is the Laplace operator, is an imaginary number, is the fundamental angular frequency, is the equivalent inductance of the AC side of the voltage source converter, , and They are the leakage inductance of the converter transformer and the bridge arm inductance of the voltage source converter; the filter Used to filter out DC components;

[0011] Compensator based Constraints, Compensators The structure in the real number field is represented as:

[0012] In the formula, and They are d Transfer function on the axis channel; , , and They are q The transfer function on the axis channel; where d Each transfer function on the axis channel is related to qThe transfer functions on the axis channels are consistent or inconsistent;

[0013] By determining the compensator and filter The parameters of the compensator are used to eliminate the high-frequency negative damping effect of the voltage source converter or to make the high-frequency impedance angle or high-frequency equivalent resistance of the voltage source converter within the required range. The parameters include d The transfer function on the axis channel and q Transfer function on axis channel, filter The cut-off frequency.

[0014] Preferably, the three-phase voltage is obtained d Axis Component and q Axis Component The specific contents include: sampling the three-phase AC phase voltage, transforming the three-phase AC phase voltage through Park transformation to obtain d Axis Component and q Axis Component .

[0015] Preferably, the filter Specifically including: high-pass filter, band-pass filter or any other filter with the function of filtering out DC components.

[0016] Preferably, when Compensator only and filter hour, The specific structure is expressed as:

[0017]

[0018] when Including compensator and filter In addition, the cascade intermediate link is also included, wherein the cascade intermediate link is any structure whose influence on the high-frequency impedance characteristics of the voltage source converter is negligible.

[0019] Preferably, The parameter constraints include:

[0020] If the high-frequency impedance angle requirement range of the voltage source converter is Or the high frequency equivalent resistance requirement range is ,but The parameter constraints are expressed as or or ; To join The high-frequency equivalent resistance of the voltage source converter after To join The high frequency impedance angle of the voltage source converter after

[0021] in, It means eliminating the high frequency negative damping effect of voltage source converter;

[0022] It indicates that the high-frequency impedance angle of the voltage source converter is within the required range. It indicates that the high-frequency equivalent resistance of the voltage source converter is within the required range.

[0023] Preferably, determine the compensator The parameter methods include:

[0024] Adoption Analysis , , , , and The influence law of the high-frequency impedance characteristics of the voltage source converter is obtained to obtain the parameter range for eliminating the high-frequency negative damping effect of the voltage source converter, and then the parameters are determined by optimization;

[0025] filter The cut-off frequency is preferably a value that has little effect on the high-frequency impedance characteristics of the voltage source converter.

[0026] Preferably, determine the compensator The parameter methods include:

[0027] The high-frequency equivalent resistance and high-frequency impedance angle of the voltage source converter are expressed as:

[0028] in, To join The high-frequency equivalent resistance of the voltage source converter after To join The high-frequency impedance angle of the voltage source converter after and are function names, namely and and The correspondence between parameters;

[0029] The constraints of the high-frequency equivalent resistance or high-frequency impedance angle of the voltage source converter are:

[0030] in, and are the upper and lower limits of the high-frequency equivalent resistance of the voltage source converter, and The upper and lower limits of the high-frequency impedance angle of the voltage source converter;

[0031] (1) Obtain according to the above constraints The range of parameter variation, fix some of the parameters respectively, change any of the remaining parameters, and obtain the corresponding high-frequency impedance angle or high-frequency equivalent resistance;

[0032] (2) Determine whether the range set by the above constraints is met, and then obtain the value range of the changed parameter;

[0033] (3) Perform steps (1) to (2) for each parameter one by one until the value range of each parameter is obtained.

[0034] Preferably, the filter The cut-off frequency is preferably a value that has the least impact on the high-frequency impedance characteristics of the voltage source converter.

[0035] Preferably, Output feedforward compensation voltage and for:

[0036] Will and Respectively with the original control output voltage and The corresponding superposition output voltage is:

[0037] .

[0038] A voltage source converter cross-coupling feedforward compensation system, comprising: a sampling module and a cross-coupling feedforward compensation controller ;

[0039] Sampling module, used to obtain three-phase voltage d Axis Component and q Axis Component , and and Input to the parameterized cross-coupled feedforward compensation controller ;

[0040] Cross-coupled feedforward compensation controller , used to output feedforward compensation voltage and , and and Respectively with the original control output voltage and The corresponding superposition is then delivered to the valve control system;

[0041] in, At least the compensator and filter , compensator The constraint condition is to make the high-frequency impedance of the voltage source converter inductive, that is, the high-frequency simplified positive sequence impedance of the voltage source converter is equal to , is the Laplace operator, is an imaginary number, is the fundamental angular frequency, is the equivalent inductance of the AC side of the voltage source converter, , and They are the leakage inductance of the converter transformer and the bridge arm inductance of the voltage source converter; the filter Used to filter out DC components;

[0042] By determining Parameters can be used to eliminate the high-frequency negative damping effect of the voltage source converter or to make the high-frequency impedance angle or high-frequency equivalent resistance of the voltage source converter within the required range.

[0043] It can be seen from the above technical solution that, compared with the prior art, the present invention discloses a voltage source converter cross-coupled feedforward compensation method and system thereof, which has the following beneficial effects: the present invention uses a cross-coupled feedforward compensation controller to feedforward compensate the voltage in the original control, thereby effectively offsetting the adverse effects of link delay on the high-frequency impedance characteristics of the voltage source converter, reshaping the high-frequency impedance characteristics of the voltage source converter, and compensating for the high-frequency negative damping effect, which is suitable for practical engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 A schematic flow chart of a voltage source converter cross-coupling feedforward compensation method provided by the present invention;

[0046] Figure 2 This is a schematic diagram of a main circuit of a voltage source converter according to an embodiment of the present invention;

[0047] Figure 3 It is a schematic diagram of the structure of a cross-coupled feedforward compensation controller in an embodiment of the present invention;

[0048] Figure 4is a high-frequency impedance characteristic curve of a voltage source converter after adopting the proposed voltage source converter cross-coupling feedforward compensation method in an embodiment of the present invention; Figure 4 (a) is the positive sequence impedance characteristic curve, Figure 4 (b) is the negative sequence impedance characteristic curve. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] The present invention provides a voltage source converter cross-coupling feedforward compensation method, such as Figure 1 and Figure 2 As shown, the following steps are included:

[0051] Get three-phase voltage d Axis Component and q Axis Component ;

[0052] Will and Input to the parameterized cross-coupled feedforward compensation controller , Output feedforward compensation voltage and ;

[0053] Will and Respectively with the original control output voltage and The corresponding superposition is then delivered to the valve control system;

[0054] in, At least the compensator and filter , compensator The constraint condition is to make the high-frequency impedance of the voltage source converter inductive, that is, the high-frequency simplified positive sequence impedance of the voltage source converter is equal to , is the Laplace operator, is an imaginary number, is the fundamental angular frequency, is the equivalent inductance of the AC side of the voltage source converter, , and They are the leakage inductance of the converter transformer and the bridge arm inductance of the voltage source converter; the filter Used to filter out DC components;

[0055] Compensator based Constraints, Compensators The structure in the real number field is represented as:

[0056] In the formula, and They are d Transfer function on the axis channel; , , and They are q The transfer function on the axis channel; where d Each transfer function on the axis channel is related to q The transfer functions on the axis channels are consistent or inconsistent;

[0057] By determining the compensator and filter The parameters of the compensator are used to eliminate the high-frequency negative damping effect of the voltage source converter or to make the high-frequency impedance angle or high-frequency equivalent resistance of the voltage source converter within the required range. The parameters include d The transfer function on the axis channel and q Transfer function on axis channel, filter The cut-off frequency.

[0058] It should be noted that:

[0059] In this embodiment, the main circuit diagram of the voltage source converter is as follows: Figure 3 As shown in the figure is the transformer ratio; in addition, in this embodiment Including compensator and filter In addition to these two parts, any other links that have little impact on the high-frequency impedance characteristics of the voltage source converter can also be cascaded. and filter The two parts can be cascaded directly or through any intermediate link that has little influence on the high-frequency impedance characteristics of the voltage source converter. and filter The cascade between them has no requirements on the order. The idea of ​​using a cross-coupled feedforward compensation controller to compensate for the high-frequency negative damping effect of the voltage source converter is to weaken or eliminate the influence of link delay and try to make the high-frequency impedance of the voltage source converter purely inductive.

[0060] In order to further implement the above technical solution, obtain the three-phase voltage d Axis Component and q Axis Component The specific contents include: sampling the three-phase AC phase voltage at the common coupling point PCC, and transforming the three-phase AC phase voltage at the PCC point through Park transformation to obtain d Axis Component and q Axis Component .

[0061] It should be noted that:

[0062] The high-frequency simplified positive-sequence impedance of the voltage source converter in this example can be expressed as:

[0063] in, is the equivalent inductance of the AC side of the voltage source converter, is the leakage inductance of the converter transformer, is the bridge arm inductance of the voltage source converter, is the Laplace operator, is the link delay, is the current inner loop PI controller of the voltage source converter in this example, is the fundamental angular frequency, is a cross-coupled feedforward compensation controller. In order to satisfy the compensator Constraints, that is, to make the high-frequency impedance of the voltage source converter purely inductive, that is, the high-frequency simplified positive sequence impedance of the voltage source converter shown in the above formula is equal to , then

[0064]

[0065] According to the above formula, the expression of the cross-coupled feedforward compensation controller can be obtained as follows:

[0066]

[0067] Considering that the DC component cannot be introduced into the control system to avoid affecting the steady-state performance of the control system, it is also necessary to add a DC component isolation link, that is, a filter. In addition, the above formula is only a special form of the cross-coupled feedforward compensation controller, which needs to be further expanded to a general form. The general form uses a compensator In this example, the structure of the compensator in the complex domain can be expressed as:

[0068]

[0069] Based on the above formula, the structure of the compensator in the real number domain can be obtained.

[0070] and represents the transfer function and can be either real or complex. In addition, d Axis channel and q The above transfer functions on the axis channels do not need to be completely consistent, and different transfer functions can be used.

[0071] In order to further implement the above technical solution, the filter Specifically including: high-pass filter, band-pass filter or any other filter with the function of filtering out DC components.

[0072] It should be noted that:

[0073] DC component filtering A high-pass filter, a band-pass filter, or any other link that has the function of filtering out the DC component may be used; in this embodiment, a first-order high-pass filter is selected, and its transfer function can be expressed as:

[0074] in, is the Laplace operator, , is the cutoff frequency of the first-order high-pass filter.

[0075] In order to further implement the above technical solution, Compensator only and filter hour, The specific structure is expressed as:

[0076] when Including compensator and filter In addition, the cascade intermediate link is also included, wherein the cascade intermediate link is any structure whose influence on the high-frequency impedance characteristics of the voltage source converter is negligible.

[0077] In order to further implement the above technical solution, The parameter constraints include:

[0078] If the high-frequency impedance angle requirement range of the voltage source converter is Or the high frequency equivalent resistance requirement range is ,but The parameter constraints are expressed as or or ; To join The high-frequency equivalent resistance of the voltage source converter after To join The high frequency impedance angle of the voltage source converter after

[0079] in, It means eliminating the high frequency negative damping effect of voltage source converter;

[0080] It indicates that the high-frequency impedance angle of the voltage source converter is within the required range. It indicates that the high-frequency equivalent resistance of the voltage source converter is within the required range.

[0081] In order to further implement the above technical solution, determine the compensator The parameter methods include:

[0082] Adoption Analysis , , , , and The influence law of the high-frequency impedance characteristics of the voltage source converter is obtained to obtain the parameter range for eliminating the high-frequency negative damping effect of the voltage source converter, and then the parameters are determined by optimization;

[0083] filter The cut-off frequency is preferably a value that has little effect on the high-frequency impedance characteristics of the voltage source converter.

[0084] In order to further implement the above technical solution, determine the compensator The parameter methods include:

[0085] The high-frequency equivalent resistance and high-frequency impedance angle of the voltage source converter are expressed as:

[0086] in, To join The high-frequency equivalent resistance of the voltage source converter after To join The high-frequency impedance angle of the voltage source converter after and are function names, namely and and The correspondence between parameters;

[0087] The constraints of the high-frequency equivalent resistance or high-frequency impedance angle of the voltage source converter are:

[0088] in, and are the upper and lower limits of the high-frequency equivalent resistance of the voltage source converter, and The upper and lower limits of the high-frequency impedance angle of the voltage source converter;

[0089] (1) Obtain according to the above constraints The range of parameter variation, fix some of the parameters respectively, change any of the remaining parameters, and obtain the corresponding high-frequency impedance angle or high-frequency equivalent resistance;

[0090] (2) Determine whether the range set by the above constraints is met, and then obtain the value range of the changed parameter;

[0091] (3) Perform steps (1) to (2) for each parameter one by one until the value range of each parameter is obtained.

[0092] It should be noted that:

[0093] The parameters of the cross-coupled feedforward compensation controller need to be determined according to the impedance characteristics presented by the voltage source converter. The design principle of the relevant parameters is to give priority to eliminating the high-frequency negative damping effect of the voltage source converter, and then consider reshaping the low-frequency impedance to enhance the low-frequency damping performance. The parameters of the cross-coupled feedforward compensation controller can be obtained by drawing the impedance frequency response characteristic curve of the voltage source converter, analyzing its influence on the high-frequency impedance characteristics of the voltage source converter, obtaining the parameter range that can eliminate the high-frequency negative damping effect of the voltage source converter, and then optimizing the design of relevant parameters. It can also artificially set the required range of the high-frequency impedance angle or high-frequency equivalent resistance of the voltage source converter, and then traverse and calculate the high-frequency impedance angle or high-frequency equivalent resistance of the voltage source converter under different cross-coupled feedforward compensation controller parameters to find the parameter range that meets the high-frequency impedance angle or high-frequency equivalent resistance requirements of the voltage source converter, which is the two parallel methods described above.

[0094] In this embodiment, d Axis channel and q On the shaft channel and Set up consistently and use analytics and The influence law of the high-frequency impedance characteristics of the voltage source converter is obtained to obtain the parameter range that can eliminate the high-frequency negative damping effect of the voltage source converter, and then the design method of the parameters is determined by optimization. For example, in this embodiment, and The recommended options are 20, and .in, represents the fundamental angular frequency, , and are the leakage inductance of the converter transformer and the bridge arm inductance of the voltage source converter, is the proportional coefficient of the current inner loop PI controller of the voltage source converter. You can also use the method of changing parameters one by one: first fix and , and then change , find out the differences one by one The high-frequency impedance angle or high-frequency equivalent resistance at the time of The value range of .

[0095] The cutoff frequency of the first-order high-pass filter can be selected to have a value that has little impact on the high-frequency impedance characteristics of the voltage source converter. In this embodiment, the cutoff frequency of the first-order high-pass filter is recommended to be 10 Hz.

[0096] In order to further implement the above technical solution, the filter The cut-off frequency is preferably a value that has the least impact on the high-frequency impedance characteristics of the voltage source converter.

[0097] In order to further implement the above technical solution, Output feedforward compensation voltage and for:

[0098] Will and Respectively with the original control output voltage and The corresponding superposition output voltage is:

[0099] .

[0100] A voltage source converter cross-coupling feedforward compensation system, comprising: a sampling module and a cross-coupling feedforward compensation controller ;

[0101] Sampling module, used to obtain three-phase voltage d Axis Component and q Axis Component , and and Input to the parameterized cross-coupled feedforward compensation controller ;

[0102] Cross-coupled feedforward compensation controller , used to output feedforward compensation voltage and , and and Respectively with the original control output voltage and The corresponding superposition is then delivered to the valve control system;

[0103] in, At least the compensator and filter , compensator The constraint condition is to make the high-frequency impedance of the voltage source converter inductive, that is, the high-frequency simplified positive sequence impedance of the voltage source converter is equal to , is the Laplace operator, is an imaginary number, is the fundamental angular frequency, is the equivalent inductance of the AC side of the voltage source converter, , and They are the leakage inductance of the converter transformer and the bridge arm inductance of the voltage source converter; the filter Used to filter out DC components;

[0104] By determining Parameters are used to eliminate the high-frequency negative damping effect of the voltage source converter or to make the high-frequency impedance angle or high-frequency equivalent resistance of the voltage source converter within the required range.

[0105] The present invention is further described below by verifying the high-frequency impedance characteristics of a voltage source converter:

[0106] Under the selected parameters, the high-frequency impedance characteristic curve or high-frequency equivalent resistance of the voltage source converter is calculated to verify whether the high-frequency impedance angle or high-frequency equivalent resistance of the voltage source converter meets the requirements. Among them, the high-frequency impedance angle of the voltage source converter and the high-frequency equivalent resistance requirements can be set manually to make the system achieve high-frequency stability. If the requirements are not met, the cross-coupling feedforward compensation controller parameters can be adjusted appropriately; if the requirements are met, the cross-coupling feedforward compensation controller can be put into use. After the proposed voltage source converter cross-coupling feedforward compensation method is adopted in this embodiment, the high-frequency impedance characteristic curve of the voltage source converter is as follows Figure 1 As shown. In this example, the high-frequency impedance angle requirement of the voltage source converter is set to be less than 90°. In some systems, the high-frequency impedance angle requirement of the voltage source converter can even be relaxed to less than 90.5°. It can be seen that the proposed voltage source converter cross-coupling feedforward compensation method meets the high-frequency impedance angle requirement of the voltage source converter and can be put into use.

[0107] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A voltage source converter cross-coupling feedforward compensation method, characterized in that: The following steps are involved: Get three-phase voltage d Axis Component and q Axis Component ; Will and Input to the cross-coupled feedforward compensation controller , Output feedforward compensation voltage and ; Will and Respectively with the original control output voltage and The corresponding superposition is then delivered to the valve control system; in, At least the compensator and filter , compensator The constraint condition is to make the high-frequency impedance of the voltage source converter inductive, that is, the high-frequency simplified positive sequence impedance of the voltage source converter is equal to , is the Laplace operator, is an imaginary number, is the fundamental angular frequency, is the equivalent inductance of the AC side of the voltage source converter, , and They are the leakage inductance of the converter transformer and the bridge arm inductance of the voltage source converter; the filter Used to filter out DC components; Compensator based Constraints, Compensators The structure in the real number field is represented as: In the formula, and They are d Transfer function on the axis channel; , , and They are q The transfer function on the axis channel; where d Each transfer function on the axis channel is related to q The transfer functions on the axis channels are consistent or inconsistent; By determining the compensator and filter The parameters of the compensator are used to eliminate the high-frequency negative damping effect of the voltage source converter or to make the high-frequency impedance angle or high-frequency equivalent resistance of the voltage source converter within the required range. The parameters include d The transfer function on the axis channel and q Transfer function on axis channel, filter The cut-off frequency.

2. A voltage source converter cross-coupling feedforward compensation method according to claim 1, characterized in that: Get three-phase voltage d Axis Component and q Axis Component The specific contents include: sampling the three-phase AC phase voltage, transforming the three-phase AC phase voltage through Park transformation to obtain d Axis Component and q Axis Component .

3. A voltage source converter cross-coupling feedforward compensation method according to claim 1, characterized in that: filter Specifically including: high-pass filter, band-pass filter or any other filter with the function of filtering out DC components.

4. A voltage source converter cross-coupling feedforward compensation method according to claim 1, characterized in that: when Compensator only and filter hour, The specific structure is expressed as: when Including compensator and filter In addition, the cascade intermediate link is also included, wherein the cascade intermediate link is any structure whose influence on the high-frequency impedance characteristics of the voltage source converter is negligible.

5. A voltage source converter cross-coupling feedforward compensation method according to claim 3, characterized in that: The parameter constraints include: If the high-frequency impedance angle requirement range of the voltage source converter is Or the high frequency equivalent resistance requirement range is ,but The parameter constraints are expressed as or or ; To join The high-frequency equivalent resistance of the voltage source converter after To join The high frequency impedance angle of the voltage source converter after in, It means eliminating the high frequency negative damping effect of voltage source converter; It indicates that the high-frequency impedance angle of the voltage source converter is within the required range. It indicates that the high-frequency equivalent resistance of the voltage source converter is within the required range.

6. A voltage source converter cross-coupling feedforward compensation method according to claim 1, characterized in that: Determine the compensator The parameter methods include: Adoption Analysis , , , , and The influence law of the high-frequency impedance characteristics of the voltage source converter is studied, the parameter range for eliminating the high-frequency negative damping effect of the voltage source converter is obtained, and then the parameters are determined by optimization.

7. A voltage source converter cross-coupling feedforward compensation method according to claim 1, characterized in that: Determine the compensator The parameter methods include: The high-frequency equivalent resistance and high-frequency impedance angle of the voltage source converter are expressed as: in, To join The high-frequency equivalent resistance of the voltage source converter after To join The high-frequency impedance angle of the voltage source converter after and are function names, namely and and The correspondence between parameters; The constraints of the high-frequency equivalent resistance or high-frequency impedance angle of the voltage source converter are: in, and are the upper and lower limits of the high-frequency equivalent resistance of the voltage source converter, and The upper and lower limits of the high-frequency impedance angle of the voltage source converter; (1) Obtain according to the above constraints The range of parameter variation, fix some of the parameters respectively, change any of the remaining parameters, and obtain the corresponding high-frequency impedance angle or high-frequency equivalent resistance; (2) Determine whether the range set by the above constraints is met, and then obtain the value range of the changed parameter; (3) Perform steps (1) to (2) for each parameter one by one until the value range of each parameter is obtained.

8. A voltage source converter cross-coupling feedforward compensation method according to claim 1, characterized in that: filter The cut-off frequency is preferably a value that has the least impact on the high-frequency impedance characteristics of the voltage source converter.

9. A voltage source converter cross-coupling feedforward compensation method according to claim 1, characterized in that: Output feedforward compensation voltage and for: Will and Respectively with the original control output voltage and The corresponding superposition output voltage is: 。 10. A voltage source converter cross-coupling feedforward compensation system, characterized in that: include: Sampling Module and Cross-Coupled Feedforward Compensation Controller ; Sampling module, used to obtain three-phase voltage d Axis Component and q Axis Component , and and Input to the cross-coupled feedforward compensation controller ; Cross-coupled feedforward compensation controller , used to output feedforward compensation voltage and , and and Respectively with the original control output voltage and The corresponding superposition is then delivered to the valve control system; in, At least the compensator and filter , compensator The constraint condition is to make the high-frequency impedance of the voltage source converter purely inductive, that is, the high-frequency simplified positive and negative sequence impedance of the voltage source converter is equal to , is the Laplace operator, is an imaginary number, is the fundamental angular frequency, is the equivalent inductance of the AC side of the voltage source converter, , and They are the leakage inductance of the converter transformer and the bridge arm inductance of the voltage source converter; the filter Used to filter out DC components; Compensator based Constraints, Compensators The structure in the real number field is represented as: In the formula, and They are d Transfer function on the axis channel; , , and They are q The transfer function on the axis channel; where d Each transfer function on the axis channel is related to q The transfer functions on the axis channels are consistent or inconsistent; By determining The parameters of the compensator are used to eliminate the high-frequency negative damping effect of the voltage source converter or to make the high-frequency impedance angle or high-frequency equivalent resistance of the voltage source converter within the required range. The parameters include d The transfer function on the axis channel and q Transfer function on axis channel, filter The cut-off frequency.

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