A control method and device of a SWISS rectifier under power grid unbalanced conditions, equipment and medium

Abstract

This invention discloses a control method, apparatus, device, and medium for a SWISS rectifier under grid imbalance conditions. The control method includes: acquiring initial buck circuit duty cycle information; determining buck circuit control conductance parameters based on the initial buck circuit duty cycle information, target output DC current, and grid source-side voltage information; determining the relationship between grid source-side current information, buck circuit current information, and filter capacitor current to determine a transformation matrix based on the sum of the buck circuit control conductance parameters and filter capacitor impedance parameters; and correcting the initial buck circuit duty cycle information to adjust the transformation matrix to reflect the buck circuit control conductance parameters. This solution, under grid imbalance and considering the filter condition, avoids the generation of additional reactive power on the grid side and prevents second-harmonic frequency fluctuations in the output voltage and current.

Description

Technical Field

[0001] This invention relates to the field of SWISS rectifier technology, and in particular to a control method, device, equipment and medium for SWISS rectifiers under power grid imbalance conditions. Background Technology

[0002] In recent years, the escalating global environmental pollution, energy crisis, and global warming have led to the increasingly widespread application of hydrogen production technology. Conventional hydrogen production processes require direct current (DC), therefore, hydrogen production power supplies typically need to include AC / DC conversion circuits to rectify AC power into DC power.

[0003] The SWISS rectifier is a step-down single-stage rectifier topology that has an efficiency advantage over traditional two-stage rectifier topologies. It can achieve input-side power factor correction and output-side current and power control requirements at the single-stage circuit level, perfectly matching the needs of hydrogen production power supplies and representing a potential topology for hydrogen production power supplies.

[0004] By precisely locking the amplitude and phase of the positive and negative sequence voltages of the grid using a phase-locked loop (PLL), the IVS circuit can be controlled to correctly distribute the three-phase voltage. The duty cycle of the switching transistors can be calculated based on instantaneous power theory, thereby achieving a stable output voltage and current of the SWISS rectifier. When designing the above control strategy, the influence of the input filter is usually ignored. However, the existence of the input filter itself causes topological node separation between the grid voltage and the rectifier terminal voltage, resulting in a difference between the grid voltage and current and the terminal voltage and current. This difference causes additional reactive power to be generated on the grid side when the above control strategy is actually applied. When the source-side voltage is unbalanced, it will further cause the output voltage and current to fluctuate at twice the frequency. Summary of the Invention

[0005] This invention provides a control method, device, equipment, and medium for a SWISS rectifier under grid imbalance conditions, so as to avoid the generation of additional reactive power on the grid side and avoid the second harmonic fluctuation of the output voltage and current under grid imbalance and filter consideration conditions.

[0006] To achieve the above objectives, in a first aspect, embodiments of the present invention provide a control method for a SWISS rectifier under grid imbalance conditions, the control method comprising: Obtain the initial duty cycle information of the buck converter; The control conductance parameters of the buck circuit are determined based on the initial buck circuit duty cycle information, the target output DC current, and the grid source-side voltage information. The relationship between the grid source-side current information, the buck circuit current information, and the filter capacitor current is determined so as to determine the transformation matrix based on the sum of the buck circuit control conductance parameters and the filter capacitor impedance parameters; The initial duty cycle information of the buck circuit is corrected so that the transformation matrix is ​​adjusted to the control conductance parameters of the buck circuit.

[0007] Optionally, the control conductance parameters of the buck circuit are determined based on the initial buck circuit duty cycle information, the target output DC current, and the grid source-side voltage information, including: Based on the relationship between the grid source-side voltage information, the generator terminal current information, and the initial buck circuit duty cycle information, and in conjunction with the grid source-side voltage information, the buck circuit control conductance matrix is ​​determined. Based on the buck circuit control conductance matrix, the buck circuit control conductance parameters are determined according to the initial buck circuit duty cycle information, the target output DC current, and the grid source-side voltage information.

[0008] Optionally, the relationship between the grid source-side current information, the buck circuit current information, and the filter capacitor current is determined, specifically as follows: Among them, I src,12 This refers to the power grid source-side current information; U src,12 This refers to the source-side voltage information of the power grid; Z c Here, G represents the filter capacitor impedance parameter; G is the control conductance matrix of the buck circuit; GU src,12 For the current information of the buck circuit; Z c -1 U src,12 The current is the filter capacitor current.

[0009] Optionally, the initial buck circuit duty cycle information is corrected so that the transformation matrix is ​​adjusted to the control conductance parameters of the buck circuit; The first q-axis correction factor for the duty cycle of the buck circuit is determined based on the filter capacitor impedance parameters, DC output voltage information, and grid source-side current information. The second q-axis correction factor for the duty cycle of the buck circuit is determined based on the filter capacitor impedance parameters, DC output voltage information, and grid source-side current information. The first q-axis duty cycle information in the initial buck circuit duty cycle information is corrected according to the first q-axis correction factor of the buck circuit duty cycle; The second q-axis duty cycle information in the initial buck circuit duty cycle information is corrected according to the second q-axis correction factor of the buck circuit duty cycle.

[0010] Optionally, obtain the initial buck circuit duty cycle information, including: The voltage information on the power grid source side is converted from positive to negative sequence to output the positive sequence voltage amplitude, positive sequence phase, negative sequence voltage amplitude, and negative sequence phase; The modulation parameters are determined based on the target output reference voltage and the positive sequence voltage amplitude. The unbalance parameters are determined based on the positive-sequence voltage amplitude and the negative-sequence voltage amplitude. The first d-axis duty cycle information in the initial buck circuit duty cycle information under the rotating coordinate system is determined according to the modulation parameter and the unbalance parameter, and the second d-axis duty cycle information is determined according to the unbalance parameter and the first d-axis duty cycle information. The first q-axis duty cycle information and the second q-axis duty cycle information of the buck circuit are determined based on the target output reference reactive power, the unbalance parameter, the target output DC current, the filter capacitor impedance parameter, and the positive sequence voltage amplitude.

[0011] Optionally, the method further includes: outputting a target output reference voltage based on the real-time output voltage and the target output voltage.

[0012] Secondly, embodiments of the present invention also provide a control device for a SWISS rectifier under grid imbalance conditions, the device comprising: The acquisition module is used to acquire the initial duty cycle information of the buck circuit; The first determining module is used to determine the control conductance parameters of the buck circuit based on the initial buck circuit duty cycle information, the target output DC current and the grid source-side voltage information. The third determining module is used to determine the relationship between the grid source-side current information, the buck circuit current information, and the filter capacitor current based on the instantaneous power model, so as to determine the transformation matrix according to the sum of the buck circuit control conductance parameters and the filter capacitor impedance parameters. The correction module is used to correct the initial buck circuit duty cycle information so that the transformation matrix is ​​adjusted to the control conductance parameters of the buck circuit.

[0013] Optionally, the correction module includes: The first determining unit is used to determine the q-axis correction factor of the duty cycle of the first buck circuit based on the filter capacitor impedance parameters, DC output voltage information and grid source-side current information. The second determining unit is used to determine the duty cycle q-axis correction factor of the second buck circuit based on the filter capacitor impedance parameters, DC output voltage information and grid source-side current information. The first correction unit is used to correct the first q-axis duty cycle information in the initial buck circuit duty cycle information according to the first buck circuit duty cycle q-axis correction factor. The second correction unit is used to correct the second q-axis duty cycle information in the initial buck circuit duty cycle information according to the second buck circuit duty cycle q-axis correction factor, so as to correct the initial buck circuit duty cycle information.

[0014] Thirdly, embodiments of the present invention also provide a control device for a SWISS rectifier under grid imbalance conditions. The device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the control method for the SWISS rectifier under grid imbalance conditions as described in the first aspect.

[0015] Fourthly, embodiments of the present invention also provide a storage medium containing computer-executable instructions, which, when executed by a computer processor, are used to perform the control method for a SWISS rectifier under grid imbalance conditions as described in the first aspect.

[0016] In this embodiment of the invention, the initial buck circuit duty cycle information is obtained; the buck circuit control conductance parameters are determined based on the initial buck circuit duty cycle information, the target output DC current, and the grid source-side voltage information; based on the instantaneous power model, the relationship between the grid source-side current information, the buck circuit current information, and the filter capacitor current is determined, and the transformation matrix is ​​determined based on the sum of the buck circuit control conductance parameters and the filter capacitor impedance parameters; the initial buck circuit duty cycle information is corrected so that the transformation matrix is ​​adjusted to the buck circuit control conductance parameters. In this way, by correcting the initial buck circuit duty cycle information, additional reactive power is avoided on the grid side under grid imbalance and filter consideration conditions, and second harmonic fluctuations in the output voltage and current are avoided.

[0017] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating a control method for a SWISS rectifier under power grid imbalance conditions provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of a SWISS rectifier in the prior art; Figure 3 This is a flowchart illustrating another control method for a SWISS rectifier under power grid imbalance conditions provided in an embodiment of the present invention. Figure 4 This is a flowchart illustrating another control method for a SWISS rectifier under power grid imbalance conditions provided in an embodiment of the present invention. Figure 5 This is a schematic diagram of the structure of a control device for a SWISS rectifier under power grid imbalance conditions provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0021] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0022] Figure 1This is a flowchart illustrating a control method for a SWISS rectifier under grid imbalance conditions, provided by an embodiment of the present invention. This embodiment can control the step-down switching circuit of the SWISS rectifier under grid imbalance conditions. The method can be executed by a control device for the SWISS rectifier under grid imbalance conditions. This control device can be implemented by software and / or hardware and can be configured within the control equipment of the SWISS rectifier under grid imbalance conditions. Optionally, the control equipment for the SWISS rectifier under grid imbalance conditions can be an electronic device, such as a microcomputer and microprocessor chip; this embodiment of the present invention does not impose limitations on this. Figure 1 As shown, the control method specifically includes the following steps: S110, Obtain the initial duty cycle information of the buck circuit.

[0023] This control method is applicable to SWISS rectifiers; Figure 2 This is a schematic diagram of the structure of a SWISS rectifier in the prior art; for example... Figure 2 As shown, the SWISS rectifier includes: a three-phase uncontrolled rectifier bridge 10, a filter 20, a harmonic injection circuit (IVS circuit) 30, and a DC-DC buck circuit 40. The three-phase uncontrolled rectifier bridge 10 includes diodes Dax / Dbx / Dcx in the upper arm and diodes Daz / Dbz / Dcz in the lower arm; it provides a rectification path, clamps the voltage, protects the bidirectional switches in the IVS circuit, and assists in current freewheeling, ensuring the safe operation of the IVS circuit. The filter 20 includes three-phase filter inductors 21 (La / Lb / Lc) and three-phase filter capacitors 22 (Cx / Cy / Cz); the filter can filter the input grid voltage. The IVS circuit 30 consists of three bidirectional switches Say / Sby / Scy, which achieve active high-frequency commutation by controlling the on / off combination of the three bidirectional switches. The DC-DC buck circuit 40 includes Sp / Sn. Composed of two switching transistors, diodes Dp / Dn, inductors Lp / Ln, and capacitor Cpn, this is a bipolar output DC-DC converter that converts the current ix / iy / iz output from the IVS circuit into a bipolar DC voltage Upn to supply the downstream load. The initial buck circuit duty cycle information is the duty cycle information of the SWISS rectifier without considering the filter, which can guarantee no fluctuation in output voltage and current. Since the filter 10 itself exists, the DC-DC buck circuit 40 still operates according to the initial buck circuit duty cycle information, which will cause additional reactive power to be generated on the grid side. At the same time, when the grid is unbalanced, the bipolar DC voltage Upn will further fluctuate at twice the frequency, and the output voltage and current will also fluctuate. This embodiment can first obtain the initial duty cycle information of the buck circuit, and then correct the initial duty cycle information of the buck circuit, thereby avoiding the generation of additional reactive power on the grid side and avoiding output voltage and current fluctuations.

[0024] S120. Determine the control conductance parameters of the buck circuit based on the initial buck circuit duty cycle information, the target output DC current, and the grid source side voltage information.

[0025] Specifically, the target output DC current I can be determined. DC and grid source-side voltage information U src The ratio of the initial duty cycle information DpDn to the control conductance parameter of the buck circuit can be determined by multiplying this ratio with the initial duty cycle information DpDn of the buck circuit. Thus, the control conductance parameter of the buck circuit can reflect the equivalent conductance and current carrying capacity of the DC-DC buck circuit.

[0026] S130. Based on the filter capacitor parameters and the buck circuit control conductance parameters, determine the current balance relationship between the grid source side current information, the buck circuit current information and the filter capacitor current. Based on the current balance formula, determine the transformation matrix according to the buck circuit control conductance parameters and the filter capacitor impedance parameters. According to the current balance principle, the relationship between the grid source-side current information, the buck circuit current information, and the filter capacitor current is as follows: the grid source-side current information is the sum of the buck circuit current information and the filter capacitor current; the filter capacitor parameters and the grid source-side voltage information U... src The filter capacitor current can be determined; based on the control conductance parameters of the buck circuit and the source-side voltage information U... src The current information of the buck converter circuit can be determined; thus, the source-side voltage information U of the power grid can be established. src The transformation matrix between the current information on the power grid source side and the current information on the grid source side; that is, the transformation matrix can be determined based on the sum of the control conductance parameters of the step-down circuit and the impedance parameters of the filter capacitor.

[0027] S140. Correct the initial duty cycle information of the buck circuit so that the transformation matrix is ​​adjusted to the control conductance parameters of the buck circuit.

[0028] Specifically, the control conductance parameters of the buck circuit are determined based on the initial duty cycle information of the buck circuit. Then, based on the control conductance parameters of the buck circuit and the grid source-side voltage information U... src Determine the current information of the buck converter circuit, while simultaneously considering the filter inductor and capacitor parameters and the mains voltage information U. src The filter capacitor current is determined, and the grid source-side current information is obtained by taking the filter capacitor current into account. This will result in a second harmonic frequency fluctuation, causing voltage and current fluctuations in the output. At the same time, it will also cause additional reactive power to be generated on the grid side. To avoid fluctuations in output voltage and current, and to prevent additional reactive power generation on the grid side, the initial buck circuit duty cycle information can be corrected. This corrected buck circuit control conductance parameter is then determined, ensuring that the sum of the corrected buck circuit control conductance parameter and the filter capacitor impedance parameter remains the same as the buck circuit control conductance parameter determined by the initial buck circuit duty cycle information. This is equivalent to not considering the filter capacitor current in the grid source-side current information, thus avoiding output second harmonic fluctuations, output voltage and current fluctuations, and preventing additional reactive power generation on the grid side. In this embodiment of the invention, the initial buck circuit duty cycle information is obtained; the buck circuit control conductance parameters are determined based on the initial buck circuit duty cycle information, the target output DC current, and the grid source-side voltage information; based on the buck circuit control conductance parameters and the filter capacitor impedance parameters, the relationship between the grid source-side current information, the buck circuit current information, and the filter capacitor current is determined, and the transformation matrix is ​​determined based on the sum of the buck circuit control conductance parameters and the filter capacitor impedance parameters; the initial buck circuit duty cycle information is corrected so that the transformation matrix is ​​adjusted to the buck circuit control conductance parameters. In this way, by correcting the initial buck circuit duty cycle information, additional reactive power is avoided on the grid side under grid imbalance and filter consideration conditions, and second harmonic fluctuations in the output voltage and current are avoided.

[0029] Optionally, based on the above embodiments, steps S120 and S130 can be further refined. Figure 3 This is a schematic diagram of the control process of a SWISS rectifier under another grid imbalance condition provided by an embodiment of the present invention; as shown. Figure 3 As shown, the control method specifically includes the following steps: S210, Obtain the initial duty cycle information of the buck circuit.

[0030] S220. Based on the relationship between the grid source-side voltage information, the generator terminal current information and the initial buck circuit duty cycle information, and combined with the grid source-side voltage information, determine the buck circuit control conductance matrix.

[0031] Specifically, the relationship between the generator terminal current information, the target output DC current information, and the duty cycle information of the buck converter is determined, and the control conductance expression of the buck converter is determined in conjunction with the grid source-side voltage information, including: 1) Transfer the grid source-side voltage information U src Perform positive and negative sequence transformation to determine positive and negative sequence phase. , and its amplitude and For ease of analysis, the positive sequence voltage amplitude is used as the basis. The voltage is normalized to a per-unit value, and the modulation index is used. Measure the output reference voltage size, Measuring the current degree of imbalance in the power grid; specifically: (1) (2) Power grid source-side voltage information U src The voltage space vector satisfies the following equation: (3) in, For positive and negative order rotation operators, This is the complex amplitude vector of the source-side voltage of the power grid; it can be used in the following text. U represents the source-side voltage information of the power grid src。

[0032] 2) Ignoring the rectifier transmission impedance, the terminal current information, the target output DC current information, and the buck circuit duty cycle information satisfy the following formula: (4) in, The three-phase components are formed by the duty cycles of the two switches in the step-down circuit; I DC The target output DC current; ix, iy, and iz are the terminal current information; 3) Perform coordinate system transformation on the terminal current information and the duty cycle information of the step-down circuit; and perform coordinate system transformation based on phasor method and positive and negative sequence phase. , Establish the terminal current information after the rotational coordinate system transformation, the duty cycle information of the step-down circuit after the rotational coordinate system transformation, and the target output DC current information I. DC The expression between them; specifically: (5) Among them, I gen,12 It also provides terminal current information; The three-phase component consisting of the duty cycles of the two switches in the step-down circuit. Component form in a dual synchronous rotating coordinate system.

[0033] 4) Establish the relationship between the generator terminal current information and the grid source-side voltage information based on expression (5) and the grid source-side voltage information after positive and negative sequence transformation; specifically: (6) 5) Determine the control conductance expression for the buck converter based on the relationship between the generator terminal current information and the grid source-side voltage information; specifically: (7) S230. Based on the buck circuit control conductance matrix, determine the buck circuit control conductance parameters according to the initial buck circuit duty cycle information, the target output DC current and the grid source side voltage information.

[0034] Specifically, the duty cycle information of the buck circuit dd1 / dd2 / dq1 / dq2 and the target output DC current I are used. DC and the positive sequence voltage amplitude in the power grid source-side voltage information Substituting into equation (7) above, the control conductance parameter G of the step-down circuit can be determined.

[0035] S240. Determine the relationship between the grid source-side current information, the buck circuit current information, and the filter capacitor current, and determine the transformation matrix based on the sum of the buck circuit control conductance parameters and the filter capacitor impedance parameters. Specifically, determining the relationship between the grid source-side current information, the buck circuit current information, and the filter capacitor current involves: (8) Where Isrc,12 represents the grid source-side current information; Usrc,12 represents the grid source-side voltage information; Z c Here are the filter capacitor impedance parameters; G is the buck circuit control conductance matrix; GUsrc,12 is the buck circuit current information; Z c -1 Usrc,12 represents the filter capacitor current. According to the phasor method, Z... c for: (9) Based on the above expression (8), the transformation matrix is ​​determined according to the sum of the control conductance parameter (7) of the step-down circuit and the impedance parameter (9) of the filter capacitor, specifically as follows: (10) S250. Correct the initial duty cycle information of the buck circuit so that the transformation matrix is ​​adjusted to the control conductance parameters of the buck circuit.

[0036] Specifically, the initial buck circuit duty cycle information is corrected. This correction ensures that the sum of the corrected buck circuit control conductance parameter and the filter capacitor impedance parameter remains the same as the initial buck circuit duty cycle information used to determine the buck circuit control conductance parameter. This is equivalent to excluding the filter capacitor current from the grid source-side current information, thus avoiding output second harmonic fluctuations and output voltage and current fluctuations. Simultaneously, it prevents the generation of additional reactive power on the grid side. In this embodiment of the invention, the relationship between the grid source-side current information, the generator terminal current information, and the buck circuit duty cycle information is specifically determined, and the buck circuit control conductance expression is determined in conjunction with the grid source-side voltage information. Based on the buck circuit control conductance matrix, the buck circuit control conductance parameters are determined according to the initial buck circuit duty cycle information, the target output DC current, and the grid source-side voltage information. In this way, the initial buck circuit duty cycle information is corrected so that the transformation matrix is ​​adjusted to the buck circuit control conductance parameters. This achieves the avoidance of additional reactive power generation on the grid side and the avoidance of second harmonic fluctuations in the output voltage and current under grid imbalance and filter consideration conditions.

[0037] Optionally, based on the above embodiments, steps S210 and S250 can be further refined. Figure 4 This is a flowchart illustrating another commutation control method for a SWISS rectifier IVS circuit provided in an embodiment of the present invention; as shown below. Figure 4 As shown, the control method specifically includes the following steps: S310: Obtain the initial duty cycle information of the buck converter circuit.

[0038] Specifically, the determination of the initial duty cycle information of the buck circuit is as follows: 1) Transfer the grid source-side voltage information U src Perform positive and negative sequence transformation to determine positive and negative sequence phase. , and its amplitude and For ease of analysis, the positive sequence voltage amplitude is used as the basis. The voltage is normalized to a per-unit value, and the modulation index is used. Measure the output reference voltage size, To measure the current degree of imbalance in the power grid; as shown in equations (1) and (2) above. 2) Ignoring the rectifier transmission impedance, based on the grid voltage orientation principle and instantaneous power theory, when the influence of the input filter is not considered and the grid voltage and the generator terminal voltage are regarded as the same voltage, the complex amplitude vector of the generator terminal current satisfies the following formula: (11) Combining positive and negative magnitude values and That is, as shown in the following formula: (12) Correspondingly, the rectifier transmission power is: (13) For active power, its DC component needs to be controlled while its second harmonic fluctuation component is suppressed, so that P1 and P2 are zero and P0 is maintained at Pref. For reactive power, only its DC component Q0 is considered in order to control the power factor on the grid side. Therefore, the control of the SWISS rectifier can be specifically as follows: (14) Considering that the terminal current information, the target output DC current information, and the duty cycle information of the step-down circuit satisfy the following formula: i.e., the above formula (4): (4) Simultaneously considering power conservation, specifically: (15) Then we can get: (16) At this point, from the above equation (16), we can obtain: no reference value for transmission power is required; only a reference value for the output voltage is needed to achieve open-loop control. The duty cycle component is calculated according to the following formula: (17) Specifically, according to the above formula (17): obtaining the initial buck circuit duty cycle information includes: converting the grid source-side voltage information into positive and negative sequence to output the positive sequence voltage amplitude U. src,1m Positive sequence phase, negative sequence voltage amplitude U src,2m and negative sequence phase; based on the target output reference voltage Uref (the target output reference voltage Uref can be based on the real-time output voltage and the target output voltage) and the positive sequence voltage amplitude U src,1m Determine the modulation parameter M; based on the positive sequence voltage amplitude U src,1m and negative sequence voltage amplitude U src,2m Determine the unbalance parameters Based on the modulation parameter M and the imbalance parameter Determine the first d-axis duty cycle information d in the initial buck circuit duty cycle information under the rotating coordinate system. d1 And based on the unbalance parameter The duty cycle information of the first d-axis is used to determine the duty cycle information of the second d-axis. d2 Based on the target output reference reactive power Qref and the unbalance parameter. Target output DC current I DC Filter capacitor impedance parameter Z C and positive sequence voltage amplitude U src,1m Determine the first q-axis duty cycle information d of the buck circuit q1 and the second q-axis duty cycle information d q2 .

[0039] S320. Based on the relationship between the grid source-side voltage information, the generator terminal current information, and the initial buck circuit duty cycle information, and combined with the grid source-side voltage information, determine the buck circuit control conductance matrix.

[0040] S330. Based on the buck circuit control conductance matrix, determine the buck circuit control conductance parameters according to the initial buck circuit duty cycle information, the target output DC current and the grid source side voltage information.

[0041] S340. Determine the relationship between the grid source-side current information, the buck circuit current information, and the filter capacitor current, and determine the transformation matrix based on the sum of the buck circuit control conductance parameters and the filter capacitor impedance parameters.

[0042] S350: Correct the initial duty cycle information of the buck circuit and output different q-axis correction factors so that the transformation matrix is ​​adjusted to the control conductance parameters of the buck circuit.

[0043] Specifically, the grid source-side current information is determined based on the initial buck circuit duty cycle information and the filter capacitor impedance parameters; that is: (18) Correspondingly, combining equations (4) and (10) above, we can obtain: (19) The instantaneous power formula was used to calculate the voltage and current of the current power grid, and the following results were obtained: (20) Analyzing equation (20) above, it can be seen that due to the influence of the input filter, The value is no longer zero, meaning the rectifier's transmitted power exhibits second-harmonic fluctuations, and the output voltage and current also fluctuate. Simultaneously, the reactive power on the grid side... Leading bias component appears . , All of these are only related to grid parameters and input filter capacitors. Therefore, the lighter the load condition, the greater the proportion of the above fluctuations and reactive power.

[0044] To quantitatively correct the initial duty cycle information of the buck converter, a bias phase can be added to the positive and negative sequence quadrature axis components of the duty cycle to counteract the influence of the filter capacitor. To completely suppress its fluctuations, the bias terms of the positive and negative sequence quadrature axis components must respectively satisfy the following relationship: (twenty one) From the above formula, it can be seen that: the quantitative correction of the initial buck circuit duty cycle information is specifically based on the filter capacitor impedance parameter Z. C DC output voltage information I DC and the positive sequence voltage amplitude U in the power grid source-side current information src,1mDetermine the first q-axis correction factor for the duty cycle of the buck converter. dq1; Specifically, it refers to: transferring the grid source-side voltage information U src Perform positive-to-negative sequence conversion to output positive-sequence voltage amplitude U src,1m and negative sequence voltage amplitude U src,2m According to the filter capacitance impedance parameter Z C and positive sequence voltage amplitude U src,1m The conversion factor is determined by the product of the conversion factor and the DC output voltage information I. DC The ratio is used to determine the first q-axis correction factor for the duty cycle of the step-down circuit, and the negative value is taken.

[0045] Based on the filter capacitance and impedance parameter Z C DC output voltage information I DC The second q-axis correction factor for the duty cycle of the step-down circuit is determined based on the grid source-side current information. dq2; Specifically, it involves converting the voltage information from the grid source side into positive and negative sequences to output the positive sequence voltage amplitude U. src,1m and negative sequence voltage amplitude U src,2m According to the filter capacitance impedance parameter Z C and positive sequence voltage amplitude U src,1m The product determines the conversion factor; the ratio of the conversion factor to the DC output voltage information determines the second q-axis correction factor for the buck circuit duty cycle. dq2.

[0046] Based on the first q-axis correction factor of the buck circuit duty cycle dq1 corrects the first q-axis duty cycle information in the initial buck circuit duty cycle information; specifically... (twenty two) Based on the second q-axis correction factor of the buck circuit duty cycle dq2 corrects the second q-axis duty cycle information in the initial buck circuit duty cycle information to correct the initial buck circuit duty cycle information.

[0047] (twenty three) It is understandable that the first d-axis duty cycle information of the buck circuit is d d1 and the second d-axis duty cycle information d d2 The duty cycle remains unchanged; that is, the corrected duty cycle of the buck converter is: (twenty four) In this embodiment of the invention, the initial buck circuit duty cycle information is obtained; the control conductance parameters of the buck circuit are determined based on the initial buck circuit duty cycle information, the target output DC current, and the grid source-side voltage information; based on the instantaneous power model, a relationship table is determined between the grid source-side current information, the buck circuit current information, and the filter capacitor current, and the transformation matrix is ​​determined based on the sum of the buck circuit control conductance parameters and the filter capacitor impedance parameters; specifically, the initial buck circuit duty cycle information is corrected so that the transformation matrix is ​​adjusted to the buck circuit control conductance parameters. In this way, by correcting the initial buck circuit duty cycle information, under the conditions of grid imbalance and considering the filter, the generation of additional reactive power on the grid side is avoided, and the second harmonic fluctuation of the output voltage and current is avoided.

[0048] This invention also provides a control device for a SWISS rectifier under grid imbalance conditions. This control device can execute the control method for a SWISS rectifier under grid imbalance conditions provided in any embodiment of this invention, and has the corresponding functional modules and beneficial effects of the method. Figure 5 This is a schematic diagram of the structure of a control device for a SWISS rectifier under power grid imbalance conditions provided in an embodiment of the present invention; as shown. Figure 5 As shown, the control device for the SWISS rectifier under the condition of power grid imbalance includes: Module 100 is used to acquire the initial duty cycle information of the buck circuit; The first determining module 200 is used to determine the control conductance parameters of the buck circuit based on the initial buck circuit duty cycle information, the target output DC current and the grid source side voltage information. The second determining module 300 is used to determine the relationship between the grid source-side current information, the buck circuit current information and the filter capacitor current, so as to determine the transformation matrix based on the sum of the buck circuit control conductance parameters and the filter capacitor impedance parameters. The correction module is used to correct the initial duty cycle information of the buck circuit so that the transformation matrix is ​​adjusted to the control conductance parameters of the buck circuit.

[0049] Optionally, the first determined module 200 is as follows: Based on the relationship between grid source-side voltage information, generator terminal current information and initial buck circuit duty cycle information, and combined with grid source-side voltage information, the buck circuit control conductance matrix is ​​determined; Based on the buck circuit control conductance matrix, the buck circuit control conductance parameters are determined according to the initial buck circuit duty cycle information, the target output DC current, and the grid source-side voltage information.

[0050] Optionally, the second determining module 300 is as follows: Among them, I src,12 For grid source-side current information; U src,12 For grid source-side voltage information; Z c Here, G represents the filter capacitor impedance parameter; G is the control conductance matrix of the buck circuit; GU src,12 For buck circuit current information; Z c -1 U src,12 This represents the filter capacitor current.

[0051] Optional, the correction module includes; The first determining unit is used to determine the first q-axis correction factor of the buck circuit duty cycle based on the filter capacitor impedance parameters, DC output voltage information and grid source-side current information. The second determining unit is used to determine the second q-axis correction factor of the buck circuit duty cycle based on the filter capacitor impedance parameters, DC output voltage information and grid source-side current information. The first correction unit is used to correct the first q-axis duty cycle information in the initial buck circuit duty cycle information according to the first q-axis correction factor of the buck circuit duty cycle; The second correction unit is used to correct the second q-axis duty cycle information in the initial buck circuit duty cycle information according to the second q-axis correction factor of the buck circuit duty cycle, so as to correct the initial buck circuit duty cycle information.

[0052] Optionally, obtain module 100, specifically: The voltage information from the power grid source side is converted into positive and negative sequences to output the positive sequence voltage amplitude, positive sequence phase, negative sequence voltage amplitude, and negative sequence phase. Determine the modulation parameters based on the target output reference voltage and the positive sequence voltage amplitude; The unbalance parameters are determined based on the positive-sequence voltage amplitude and the negative-sequence voltage amplitude. Based on the modulation parameters and unbalance parameters, the first d-axis duty cycle information in the initial buck circuit duty cycle information under the rotating coordinate system is determined, and the second d-axis duty cycle information is determined based on the unbalance parameters and the first d-axis duty cycle information.

[0053] The first q-axis duty cycle and the second q-axis duty cycle of the buck converter are determined based on the target output reference reactive power, unbalance parameters, target output DC current, filter capacitor impedance parameters, and positive sequence voltage amplitude.

[0054] Optionally, the device further includes a third determining module for outputting a target output reference voltage based on the real-time output voltage and the target output voltage.

[0055] This invention also provides an electronic device. Figure 6This is a schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. The electronic device is intended to represent various forms of digital computers, such as embedded computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices (such as helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the invention described and / or claimed herein.

[0056] like Figure 6 As shown, electronic device 011 includes at least one processor 11 and a memory, such as a read-only memory (ROM) 12 or a random access memory (RAM) 13, communicatively connected to the at least one processor 11. The memory stores computer programs executable by the at least one processor. The processor 11 can perform various appropriate actions and processes based on the computer program stored in the ROM 12 or loaded into the RAM 13 from storage unit 18. The RAM 13 can also store various programs and data required for the operation of electronic device 011. The processor 11, ROM 12, and RAM 13 are interconnected via a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0057] Multiple components in electronic device 011 are connected to I / O interface 15, including: input unit 16, such as keyboard, mouse, etc.; output unit 17, such as various types of displays, speakers, etc.; storage unit 18, such as disk, optical disk, etc.; and communication unit 19, such as network card, modem, wireless transceiver, etc. Communication unit 19 allows electronic device 011 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0058] Processor 11 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. Processor 11 performs the various methods and processes described above, such as a control method for a SWISS rectifier under grid imbalance conditions.

[0059] In some embodiments, a control method for a SWISS rectifier under grid imbalance conditions can be implemented as a computer program tangibly contained in a computer-readable storage medium, such as storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed on electronic device 011 via ROM 12 and / or communication unit 19. When the computer program is loaded into RAM 13 and executed by processor 11, one or more steps of the control method for a SWISS rectifier under grid imbalance conditions described above can be performed. Alternatively, in other embodiments, processor 11 can be configured to perform a control method for a SWISS rectifier under grid imbalance conditions by any other suitable means (e.g., by means of firmware).

[0060] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), payload-programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.

[0061] Computer programs used to implement the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the processor, the computer programs cause the functions / operations specified in the flowcharts and / or block diagrams to be performed. The computer programs may be executed entirely on a machine, partially on a machine, or as a standalone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0062] In the context of this invention, a computer-readable storage medium can be a tangible medium that may contain or store a computer program for use by or in conjunction with an instruction execution system, apparatus, or device. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination thereof. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0063] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).

[0064] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as data servers), or middleware components (e.g., application servers), or frontend components (e.g., user computers with graphical user interfaces or web browsers through which users can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., communication networks). Examples of communication networks include local area networks (LANs), wide area networks (WANs), blockchain networks, and the Internet.

[0065] A computing system can include clients and servers. Clients and servers are generally located far apart and typically interact through communication networks. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or cloud host, which is a hosting product within the cloud computing service system to address the shortcomings of traditional physical hosts and VPS services, such as high management difficulty and weak business scalability.

[0066] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0067] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

[0068] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A control method for a SWISS rectifier under power grid imbalance conditions, characterized in that, include: Obtain the initial duty cycle information of the buck converter; The control conductance parameters of the buck circuit are determined based on the initial buck circuit duty cycle information, the target output DC current, and the grid source-side voltage information. The relationship between the grid source-side current information, the buck circuit current information, and the filter capacitor current is determined so as to determine the transformation matrix based on the sum of the buck circuit control conductance parameters and the filter capacitor impedance parameters; The initial duty cycle information of the buck circuit is corrected so that the transformation matrix is ​​adjusted to the control conductance parameters of the buck circuit.

2. The control method for a SWISS rectifier under power grid imbalance conditions according to claim 1, characterized in that, The control conductance parameters of the buck circuit are determined based on the initial buck circuit duty cycle information, the target output DC current, and the grid source-side voltage information, including: Based on the relationship between the grid source-side voltage information, the generator terminal current information, and the initial buck circuit duty cycle information, and in conjunction with the grid source-side voltage information, the buck circuit control conductance matrix is ​​determined. Based on the buck circuit control conductance matrix, the buck circuit control conductance parameters are determined according to the initial buck circuit duty cycle information, the target output DC current, and the grid source-side voltage information.

3. The control method for a SWISS rectifier under power grid imbalance conditions according to claim 1, characterized in that, The relationship between the grid source-side current information, the buck circuit current information, and the filter capacitor current is determined as follows: Among them, I src,12 This refers to the power grid source-side current information; U src,12 This refers to the source-side voltage information of the power grid; Z c Here, G represents the filter capacitor impedance parameter; G is the control conductance matrix of the buck circuit; GU src,12 For the current information of the buck circuit; Z c -1 U src,12 The current is the filter capacitor current.

4. The control method for a SWISS rectifier under power grid imbalance conditions according to claim 1, characterized in that, The initial duty cycle information of the buck circuit is corrected so that the transformation matrix is ​​adjusted to the control conductance parameters of the buck circuit; The first q-axis correction factor for the duty cycle of the buck circuit is determined based on the filter capacitor impedance parameters, DC output voltage information, and grid source-side current information. The second q-axis correction factor for the duty cycle of the buck circuit is determined based on the filter capacitor impedance parameters, DC output voltage information, and grid source-side current information. The first q-axis duty cycle information in the initial buck circuit duty cycle information is corrected according to the first q-axis correction factor of the buck circuit duty cycle; The second q-axis duty cycle information in the initial buck circuit duty cycle information is corrected according to the second q-axis correction factor of the buck circuit duty cycle.

5. The control method for a SWISS rectifier under power grid imbalance conditions according to claim 1, characterized in that, Obtain the initial duty cycle information of the buck converter, including: The voltage information on the power grid source side is converted from positive to negative sequence to output the positive sequence voltage amplitude, positive sequence phase, negative sequence voltage amplitude, and negative sequence phase; The modulation parameters are determined based on the target output reference voltage and the positive sequence voltage amplitude. The unbalance parameters are determined based on the positive-sequence voltage amplitude and the negative-sequence voltage amplitude. The first d-axis duty cycle information in the initial buck circuit duty cycle information under the rotating coordinate system is determined according to the modulation parameter and the unbalance parameter, and the second d-axis duty cycle information is determined according to the unbalance parameter and the first d-axis duty cycle information. The first q-axis duty cycle information and the second q-axis duty cycle information of the buck circuit are determined based on the target output reference reactive power, the unbalance parameter, the target output DC current, the filter capacitor impedance parameter, and the positive sequence voltage amplitude.

6. The control method for a SWISS rectifier under power grid imbalance conditions according to claim 5, characterized in that, Also includes: The target output reference voltage is output based on the real-time output voltage and the target output voltage.

7. A control device for a SWISS rectifier under power grid imbalance conditions, characterized in that, include: The acquisition module is used to acquire the initial duty cycle information of the buck circuit; The first determining module is used to determine the control conductance parameters of the buck circuit based on the initial buck circuit duty cycle information, the target output DC current and the grid source-side voltage information. The third determining module is used to determine the relationship between the grid source-side current information, the buck circuit current information, and the filter capacitor current based on the instantaneous power model, so as to determine the transformation matrix according to the sum of the buck circuit control conductance parameters and the filter capacitor impedance parameters. The correction module is used to correct the initial buck circuit duty cycle information so that the transformation matrix is ​​adjusted to the control conductance parameters of the buck circuit.

8. The control device for a SWISS rectifier under power grid imbalance conditions according to claim 7, characterized in that, The correction module includes: The first determining unit is used to determine the q-axis correction factor of the duty cycle of the first buck circuit based on the filter capacitor impedance parameters, DC output voltage information and grid source-side current information. The second determining unit is used to determine the duty cycle q-axis correction factor of the second buck circuit based on the filter capacitor impedance parameters, DC output voltage information and grid source-side current information. The first correction unit is used to correct the first q-axis duty cycle information in the initial buck circuit duty cycle information according to the first buck circuit duty cycle q-axis correction factor. The second correction unit is used to correct the second q-axis duty cycle information in the initial buck circuit duty cycle information according to the second buck circuit duty cycle q-axis correction factor, so as to correct the initial buck circuit duty cycle information.

9. A control device for a SWISS rectifier under power grid imbalance conditions, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the control method for the SWISS rectifier under power grid imbalance conditions as described in any one of claims 1-6.

10. A storage medium containing computer-executable instructions, characterized in that, The computer-executable instructions, when executed by a computer processor, are used to perform the control method for the SWISS rectifier under power grid imbalance conditions as described in any one of claims 1-6.

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