A method and device for calculating design parameters of a multi-conversion station same-type transformer

Abstract

This application discloses a method and apparatus for calculating design parameters of identical transformers for multiple converter stations. The method includes: acquiring basic transformer data for the rectifier and inverter sides, and calculating the short-circuit impedance for the rectifier and inverter sides; determining the equivalent inductive voltage drop on the rectifier side and the equivalent inductive voltage drop on the inverter side based on the short-circuit impedance; calculating the ideal no-load voltage of the identical transformers; and calculating the design parameters of the identical transformers based on the ideal no-load voltage and the basic transformer data using the same transformer parameter calculation formula. By calculating the design parameters of identical transformers on the rectifier and inverter sides of the DC transmission system, and then setting identical transformers on the rectifier and inverter sides according to the obtained design parameters, the number of spare converter transformers can be reduced, the duplication of transformer design and testing can be avoided, and equipment investment can be reduced.

Description

Technical Field

[0001] This application relates to the field of transformer technology, and in particular to a method and apparatus for calculating design parameters of a transformer of the same type used in multiple converter stations. Background Technology

[0002] In conventional DC design, converter transformers are typically designed based on the natural power in one direction, taking into account the losses in DC transmission. The capacity of the inverter-side transformer is often lower than that of the rectifier-side transformer. In actual engineering, in order to ensure that the operating conditions of the rectifier and inverter sides are similar, the common practice is to design transformers separately according to the differences in operating conditions between the two converter stations. This results in different transformer types for each converter station, requiring separate design and type testing. The design and testing costs are relatively high, and it is also quite unfavorable for later operation and maintenance. Different spare parts need to be configured for the transformers, which also increases the cost. Summary of the Invention

[0003] This application provides a method and apparatus for calculating design parameters of the same type of transformer for multiple converter stations, which is used to solve the technical problem that the transformers of each converter station are of different types in the existing DC design, requiring separate design and different type tests, resulting in relatively high design and testing costs.

[0004] To solve the above-mentioned technical problems, the first aspect of this application provides a method for calculating design parameters of a multi-converter station type transformer, including:

[0005] Obtain the transformer basic data of the rectifier side and the inverter side, and calculate the short-circuit impedance of the rectifier side and the inverter side;

[0006] Based on the short-circuit impedance, determine the equivalent inductive voltage drop on the rectifier side and the equivalent inductive voltage drop on the inverter side;

[0007] Based on the equivalent inductive voltage drop on the rectifier side and the equivalent inductive voltage drop on the inverter side, and combined with the no-load voltage calculation formula, the ideal no-load voltage of the same type of transformer is calculated.

[0008] Based on the ideal no-load voltage and the transformer foundation data, the design parameters of the same type of transformer are calculated using the same type transformer parameter calculation formula, so as to set the transformers on the rectifier side and inverter side of the converter station according to the same type transformer design parameters.

[0009] Preferably, the transformer basic data specifically includes: transformer capacity, maximum short-circuit capacity of the AC system, rated DC current, and maximum short-circuit current that the converter station can withstand.

[0010] Preferably, the design parameters of the same type transformer specifically include: valve-side current, transformer capacity, rectifier-side transformer firing angle, and inverter-side transformer firing angle.

[0011] Preferably, the formula for calculating the no-load voltage is as follows:

[0012]

[0013]

[0014] U di0N =max(U di0NR U di0NI )

[0015] In the formula, U di0NR α is the rated no-load voltage of the rectifier-side converter transformer. N U is the rated firing angle of the rectifier-side transformer. dR I is the rated voltage of the converter station. dN For the rated current, D x R is the equivalent inductive voltage drop on the rectifier side. r U is the equivalent resistive voltage drop on the rectifier side. di0NI γ is the rated no-load voltage of the inverter-side converter transformer. N R is the rated firing angle of the inverter-side transformer, R is the DC resistance between the rectifier side and the inverter side, and X is the rated firing angle of the inverter-side transformer. I R is the equivalent inductive voltage drop on the inverter side. I U is the equivalent resistive voltage drop on the inverter side. di0N This is the ideal no-load voltage for transformers of the same type.

[0016] Preferably, the formula for calculating the parameters of the same type of transformer is as follows:

[0017]

[0018]

[0019]

[0020]

[0021] In the formula, U di0N I is the ideal no-load voltage of the same type of transformer. dN For the rated current, U dR D is the rated voltage of the converter station. x R is the equivalent inductive voltage drop on the rectifier side. r For the equivalent resistive voltage drop on the rectifier side, α' N γ' is the firing angle of the rectifier-side transformer. N X is the firing angle of the inverter-side transformer.I R is the equivalent inductive voltage drop on the inverter side. I I is the equivalent resistive voltage drop on the inverter side, R is the DC resistance between the rectifier side and the inverter side, and I is the DC resistance between the rectifier side and the inverter side. vN The valve current is measured, and S is the transformer capacity.

[0022] The second aspect of this application provides a device for calculating design parameters of a multi-converter station type transformer, including:

[0023] The short-circuit impedance calculation unit is used to obtain the transformer basic data of the rectifier side and the inverter side, and to calculate the short-circuit impedance of the rectifier side and the inverter side.

[0024] The inductive voltage drop calculation unit is used to determine the equivalent inductive voltage drop on the rectifier side and the equivalent inductive voltage drop on the inverter side based on the short-circuit impedance.

[0025] The ideal no-load voltage calculation unit is used to calculate the ideal no-load voltage of the same type of transformer based on the equivalent inductive voltage drop on the rectifier side and the equivalent inductive voltage drop on the inverter side, combined with the no-load voltage calculation formula.

[0026] The same-type design parameter calculation unit is used to calculate the same-type transformer design parameters based on the ideal no-load voltage and the transformer foundation data, using the same-type transformer parameter calculation formula, so as to set the transformers on the rectifier side and inverter side of the converter station according to the same-type transformer design parameters.

[0027] Preferably, the transformer basic data specifically includes: transformer capacity, maximum short-circuit capacity of the AC system, rated DC current, and maximum short-circuit current that the converter station can withstand.

[0028] Preferably, the design parameters of the same type transformer specifically include: valve-side current, transformer capacity, rectifier-side transformer firing angle, and inverter-side transformer firing angle.

[0029] Preferably, the formula for calculating the no-load voltage is as follows:

[0030]

[0031]

[0032] U di0N =max(U di0NR U di0NI )

[0033] In the formula, U di0NR α is the rated no-load voltage of the rectifier-side converter transformer. N U is the rated firing angle of the rectifier-side transformer. dR I is the rated voltage of the converter station. dN For the rated current, Dx R is the equivalent inductive voltage drop on the rectifier side. r U is the equivalent resistive voltage drop on the rectifier side. di0NI γ is the rated no-load voltage of the inverter-side converter transformer. N R is the rated firing angle of the inverter-side transformer, R is the DC resistance between the rectifier side and the inverter side, and X is the rated firing angle of the inverter-side transformer. I R is the equivalent inductive voltage drop on the inverter side. I U is the equivalent resistive voltage drop on the inverter side. di0N This is the ideal no-load voltage for transformers of the same type.

[0034] Preferably, the formula for calculating the parameters of the same type of transformer is as follows:

[0035]

[0036]

[0037]

[0038]

[0039] In the formula, U di0N I is the ideal no-load voltage of the same type of transformer. dN For the rated current, U dR D is the rated voltage of the converter station. x R is the equivalent inductive voltage drop on the rectifier side. r For the equivalent resistive voltage drop on the rectifier side, α' N γ' is the firing angle of the rectifier-side transformer. N X is the firing angle of the inverter-side transformer. I R is the equivalent inductive voltage drop on the inverter side. I I is the equivalent resistive voltage drop on the inverter side, R is the DC resistance between the rectifier side and the inverter side, and I is the DC resistance between the rectifier side and the inverter side. vN The valve current is measured, and S is the transformer capacity.

[0040] As can be seen from the above technical solutions, the embodiments of this application have the following advantages:

[0041] The solution provided in this application calculates the design parameters of identical transformers on the rectifier and inverter sides of a DC transmission system. Then, based on the obtained design parameters, identical transformers are set on both the rectifier and inverter sides. This reduces the need for spare converter transformers, avoids redundant transformer design and testing, and lowers equipment investment. It also solves the technical problem in existing DC designs where each converter station has a different transformer type, requiring separate design and testing, resulting in high design and testing costs. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a flowchart illustrating an embodiment of a method for calculating design parameters of a multi-converter station identical transformer provided in this application.

[0044] Figure 2 This is a schematic diagram of an embodiment of a device for calculating design parameters of a multi-converter station type transformer provided in this application. Detailed Implementation

[0045] This application provides a method and apparatus for calculating design parameters of the same type of transformer for multiple converter stations, which solves the technical problem that the transformers of each converter station are of different types in the existing DC design, requiring separate design and different type tests, resulting in relatively high design and testing costs.

[0046] To make the inventive objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0047] Please see Figure 1 The first embodiment of this application provides a method for calculating design parameters of a multi-converter station type transformer, including:

[0048] Step 101: Obtain the transformer foundation data of the rectifier side and inverter side, and calculate the short-circuit impedance of the rectifier side and inverter side.

[0049] More specifically, the transformer basic data mentioned in this step includes: transformer capacity, maximum short-circuit capacity of the AC system, rated DC current, and maximum short-circuit current that the converter station can withstand.

[0050] In step 101, calculate the short-circuit impedance of the transformers on both the rectifier and inverter sides:

[0051]

[0052] Wherein, the subscript R represents the rectifier side, I represents the inverter side, and S represents the inverter side. nThis refers to the original capacity of the transformer, typically calculated using traditional design methods for different types of transformers, S. kmax For the maximum short-circuit capacity of the AC system, I dN For the rated DC current, I kmax This is the maximum short-circuit current that the converter station can withstand.

[0053] The short-circuit impedances on the rectifier and inverter sides are calculated using the above formulas, and the final short-circuit impedance is determined using the following formula:

[0054] X r =max(X rR X rI )

[0055] Step 102: Determine the equivalent inductive voltage drop on the rectifier side and the equivalent inductive voltage drop on the inverter side based on the short-circuit impedance.

[0056] Step 103: Based on the equivalent inductive voltage drop on the rectifier side and the equivalent inductive voltage drop on the inverter side, and combined with the no-load voltage calculation formula, calculate the ideal no-load voltage of the same type of transformer.

[0057] It should be noted that the formula for calculating the rated no-load voltage of the rectifier-side transformer is as follows:

[0058]

[0059] Among them U di0NR U is the rated no-load voltage of the rectifier-side converter transformer, α is the rated firing angle of the rectifier-side converter transformer, and U is the rated firing angle of the rectifier-side converter transformer. dR I is the rated voltage on the rectifier side. dN For the rated current, D x The equivalent inductive voltage drop on the rectifier side is typically half the short-circuit impedance, i.e., X. r / 2,R r This is the equivalent resistive voltage drop on the rectifier side, which is generally a fixed value.

[0060] The rated no-load voltage of the inverter-side transformer is calculated using the following formula:

[0061]

[0062] Among them U di0NI U is the rated no-load voltage of the inverter-side converter transformer, γ is the rated firing angle, and U is the rated firing angle. dR I is the rated voltage on the rectifier side. dN R is the rated current, R is the DC resistance between the rectifier side and the inverter side, and X is the rated current. I R is the equivalent inductive voltage drop on the inverter side, which is generally equal to the equivalent inductive voltage drop on the rectifier side. I This is the equivalent resistive voltage drop on the inverter side, which is generally a fixed value.

[0063] Next, compare U di0NR with U di0NI Take the larger value U di0N This value serves as the ideal no-load voltage for transformers of the same type.

[0064] U di0N =max(U di0NR U di0NI )

[0065] Step 104: Based on the ideal no-load voltage and combined with the transformer foundation data, calculate the design parameters of the same type of transformer using the same type transformer parameter calculation formula, so as to set the transformers on the rectifier side and inverter side of the converter station according to the same type transformer design parameters.

[0066] More specifically, the design parameters for the same type of transformer include: valve-side current, transformer capacity, rectifier-side transformer firing angle, and inverter-side transformer firing angle.

[0067] In step 104, the valve-side current and transformer capacity of the converter transformer are calculated using the following formulas:

[0068]

[0069]

[0070] The aforementioned valve-side current I vN The transformer capacity S is the design parameter for the same type of transformer.

[0071] Meanwhile, considering that using the same type of converter transformer will affect the rated angle of the two stations, it is necessary to go back and recalculate the rated firing angle.

[0072] Specifically, the final firing angles of the rectifier and inverter sides can be calculated using the following formula.

[0073]

[0074]

[0075] In the formula, U di0N I is the ideal no-load voltage of the same type of transformer. dN For the rated current, U dR D is the rated voltage of the converter station. x R is the equivalent inductive voltage drop on the rectifier side. r For the equivalent resistive voltage drop on the rectifier side, α' N γ' is the firing angle of the rectifier-side transformer. N X is the firing angle of the inverter-side transformer. I R is the equivalent inductive voltage drop on the inverter side. IR is the equivalent resistive voltage drop on the inverter side, and R is the DC resistance between the rectifier side and the inverter side.

[0076] The above content is a detailed description of an embodiment of a method for calculating design parameters of a transformer of the same type for multiple converter stations provided in this application. The following is a detailed description of an embodiment of a device for calculating design parameters of a transformer of the same type for multiple converter stations provided in this application.

[0077] Please see Figure 2 The second embodiment of this application provides a device for calculating design parameters of a multi-converter station type transformer, including:

[0078] The short-circuit impedance calculation unit 201 is used to obtain the transformer basic data of the rectifier side and the inverter side, and to calculate the short-circuit impedance of the rectifier side and the inverter side.

[0079] The inductive voltage drop calculation unit 202 is used to determine the equivalent inductive voltage drop on the rectifier side and the equivalent inductive voltage drop on the inverter side based on the short-circuit impedance.

[0080] The ideal no-load voltage calculation unit 203 is used to calculate the ideal no-load voltage of the same type of transformer based on the equivalent inductive voltage drop on the rectifier side and the equivalent inductive voltage drop on the inverter side, combined with the no-load voltage calculation formula.

[0081] The same-type design parameter calculation unit 204 is used to calculate the same-type transformer design parameters based on the ideal no-load voltage and the transformer foundation data, using the same-type transformer parameter calculation formula, so as to set the transformers on the rectifier side and inverter side of the converter station according to the same-type transformer design parameters.

[0082] Furthermore, the basic transformer data specifically includes: transformer capacity, maximum short-circuit capacity of the AC system, rated DC current, and maximum short-circuit current that the converter station can withstand.

[0083] Furthermore, the specific design parameters for the same type of transformer include: valve-side current, transformer capacity, rectifier-side transformer firing angle, and inverter-side transformer firing angle.

[0084] Furthermore, the specific formula for calculating the no-load voltage is as follows:

[0085]

[0086]

[0087] U di0N =max(U di0NR U di0NI )

[0088] In the formula, U di0NR U is the rated no-load voltage of the rectifier-side converter transformer, α is the rated firing angle of the rectifier-side transformer, and U is the rated firing angle of the rectifier-side transformer. dRI is the rated voltage of the converter station. dN For the rated current, D x R is the equivalent inductive voltage drop on the rectifier side. r U is the equivalent resistive voltage drop on the rectifier side. di0NI X is the rated no-load voltage of the inverter-side converter transformer, γ is the rated firing angle of the inverter-side transformer, R is the DC resistance between the rectifier side and the inverter side, and X is the rated no-load voltage of the inverter-side converter transformer. I R is the equivalent inductive voltage drop on the inverter side. I U is the equivalent resistive voltage drop on the inverter side. di0N This is the ideal no-load voltage for transformers of the same type.

[0089] Furthermore, the specific formula for calculating the parameters of the same type of transformer is as follows:

[0090]

[0091]

[0092]

[0093]

[0094] In the formula, U di0N I is the ideal no-load voltage of the same type of transformer. dN For the rated current, U dR D is the rated voltage of the converter station. x R is the equivalent inductive voltage drop on the rectifier side. r For the equivalent resistive voltage drop on the rectifier side, α' N γ' is the firing angle of the rectifier-side transformer. N X is the firing angle of the inverter-side transformer. I R is the equivalent inductive voltage drop on the inverter side. I R is the equivalent resistive voltage drop on the inverter side, and R is the DC resistance between the rectifier side and the inverter side.

[0095] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the terminals, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0096] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0097] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application 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 embodiments of the application described herein can be implemented, for example, 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.

[0098] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0099] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0100] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0101] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for calculating design parameters of a transformer of the same type used in multiple converter stations, characterized in that, include: Obtain the transformer basic data of the rectifier side and the inverter side, and calculate the short-circuit impedance of the rectifier side and the inverter side. The transformer basic data specifically includes: transformer capacity, maximum short-circuit capacity of AC system, rated DC current and maximum short-circuit current that converter station can withstand. Based on the short-circuit impedance, determine the equivalent inductive voltage drop on the rectifier side and the equivalent inductive voltage drop on the inverter side; Based on the equivalent inductive voltage drop on the rectifier side and the equivalent inductive voltage drop on the inverter side, and combined with the no-load voltage calculation formula, the ideal no-load voltage of the same type of transformer is calculated. Based on the ideal no-load voltage and the transformer foundation data, the design parameters of the same type of transformer are calculated using the same type transformer parameter calculation formula. In order to set the transformers on the rectifier side and inverter side of the converter station according to the same type transformer design parameters, the same type transformer design parameters specifically include: valve side current, transformer capacity, rectifier side transformer firing angle and inverter side transformer firing angle.

2. The method for calculating design parameters of a multi-converter station identical transformer according to claim 1, characterized in that, The specific formula for calculating the no-load voltage is as follows: In the formula, U di0NR α is the rated no-load voltage of the rectifier-side converter transformer. N U is the rated firing angle of the rectifier-side transformer. dR I is the rated voltage of the converter station. dN For the rated current, D x R is the equivalent inductive voltage drop on the rectifier side. r U is the equivalent resistive voltage drop on the rectifier side. di0NI γ is the rated no-load voltage of the inverter-side converter transformer. N R is the rated firing angle of the inverter-side transformer, R is the DC resistance between the rectifier side and the inverter side, and X is the rated firing angle of the inverter-side transformer. I R is the equivalent inductive voltage drop on the inverter side. I This is the equivalent resistive voltage drop on the inverter side. This is the ideal no-load voltage for transformers of the same type.

3. The method for calculating design parameters of a multi-converter station identical transformer according to claim 1, characterized in that, The specific formula for calculating the parameters of the same type of transformer is as follows: In the formula, I is the ideal no-load voltage of the same type of transformer. dN For the rated current, U dR D is the rated voltage of the converter station. x R is the equivalent inductive voltage drop on the rectifier side. r The equivalent resistive voltage drop on the rectifier side. The firing angle of the rectifier-side transformer. X is the firing angle of the inverter-side transformer. I R is the equivalent inductive voltage drop on the inverter side. I I is the equivalent resistive voltage drop on the inverter side, R is the DC resistance between the rectifier side and the inverter side, and I is the DC resistance between the rectifier side and the inverter side. vN The valve current is measured, and S is the transformer capacity.

4. A device for calculating design parameters of a transformer of the same type used in multiple converter stations, characterized in that, include: Obtain the transformer basic data of the rectifier side and the inverter side, and calculate the short-circuit impedance of the rectifier side and the inverter side. The transformer basic data specifically includes: transformer capacity, maximum short-circuit capacity of AC system, rated DC current and maximum short-circuit current that converter station can withstand. Based on the short-circuit impedance, determine the equivalent inductive voltage drop on the rectifier side and the equivalent inductive voltage drop on the inverter side; Based on the equivalent inductive voltage drop on the rectifier side and the equivalent inductive voltage drop on the inverter side, and combined with the no-load voltage calculation formula, the ideal no-load voltage of the same type of transformer is calculated. Based on the ideal no-load voltage and the transformer foundation data, the design parameters of the same type of transformer are calculated using the same type transformer parameter calculation formula. In order to set the transformers on the rectifier side and inverter side of the converter station according to the same type transformer design parameters, the same type transformer design parameters specifically include: valve side current, transformer capacity, rectifier side transformer firing angle and inverter side transformer firing angle.

5. The device for calculating design parameters of a multi-converter station type transformer according to claim 4, characterized in that, The specific formula for calculating the no-load voltage is as follows: In the formula, U di0NR α is the rated no-load voltage of the rectifier-side converter transformer. N U is the rated firing angle of the rectifier-side transformer. dR I is the rated voltage of the converter station. dN For the rated current, D x R is the equivalent inductive voltage drop on the rectifier side. r U is the equivalent resistive voltage drop on the rectifier side. di0NI γ is the rated no-load voltage of the inverter-side converter transformer. N R is the rated firing angle of the inverter-side transformer, R is the DC resistance between the rectifier side and the inverter side, and X is the rated firing angle of the inverter-side transformer. I R is the equivalent inductive voltage drop on the inverter side. I This is the equivalent resistive voltage drop on the inverter side. This is the ideal no-load voltage for transformers of the same type.

6. The device for calculating design parameters of a multi-converter station type transformer according to claim 4, characterized in that, The specific formula for calculating the parameters of the same type of transformer is as follows: In the formula, I is the ideal no-load voltage of the same type of transformer. dN For the rated current, U dR D is the rated voltage of the converter station. x R is the equivalent inductive voltage drop on the rectifier side. r The equivalent resistive voltage drop on the rectifier side. The firing angle of the rectifier-side transformer. X is the firing angle of the inverter-side transformer. I R is the equivalent inductive voltage drop on the inverter side. I I is the equivalent resistive voltage drop on the inverter side, R is the DC resistance between the rectifier side and the inverter side, and I is the DC resistance between the rectifier side and the inverter side. vN The valve current is measured, and S is the transformer capacity.

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