Equivalent circuit parameter calculation method of double-current multi-winding traction transformer

Abstract

The invention discloses a method for calculating equivalent circuit parameters of a double-current-system multi-winding traction transformer, which comprises the following steps of: constructing a full-size equal-scale model of the double-current-system multi-winding traction transformer, and establishing a finite element calculation model; according to the finite element calculation model, inductance matrixes formed among the I-type winding, the II-type winding and the III-type winding under the two power supply modes of 25kV / 50Hz and 15kV / 16.7 Hz are calculated respectively; based on the formed inductance matrix, establishing a transformer multi-winding equivalent model, and considering circulating current influence caused by internal parallel connection of the I-type winding to obtain actual current sequences of the windings under short-circuit tests between the I-type winding and the III-type winding, between the I-type winding and the II-type winding and between the II-type winding and the III-type winding; according to the obtained actual current sequence of each winding, the short-circuit impedance between the I-type winding and the III-type winding, the short-circuit impedance between the I-type winding and the II-type winding and the short-circuit impedance between the II-type winding and the III-type winding are calculated through an energy method; and obtaining equivalent circuit parameters of the transformer according to the obtained short-circuit impedance value.

Description

Technical Field

[0001] The present invention relates to the field of rail transit, and in particular to a method for calculating equivalent circuit parameters of a double-current multi-winding traction transformer. Background Art

[0002] At present, my country's transportation and railway are developing rapidly, but there are multiple traction power supply systems coexisting and interconnecting in rail transportation around the world, which puts forward new requirements for my country's ability to develop multi-current electric locomotives that can realize cross-system operation. Due to the existence of different power supply systems in different regions, the emergence of multi-current electric locomotives can meet the needs of rail passenger and freight transportation across countries, regions and systems, and it is more economical in transfer costs and avoids waste of resources. As one of the core equipment of multi-current electric locomotives, the traction transformer has a large weight and occupies a large space; therefore, in the implementation of engineering applications, the traction transformer must simultaneously meet the parameter requirements of multiple traction power supply systems. In the AC power supply system, the transformer taps are set to adapt to different AC voltage levels, and in the DC power supply system, the winding connection method is changed to reuse as a DC filter inductor. Therefore, it is very important to master the operating characteristics of the dual-current traction transformer. For this dual-current traction transformer, it has technical characteristics such as multiple windings, high impedance and multiple ports, so the calculation of its equivalent impedance and its equivalent circuit parameters is large and the process is complicated.

[0003] At present, the main methods for calculating the equivalent circuit parameters of multi-winding transformers include the energy method, the magnetic circuit method, and the magnetic field-circuit coupling method. Among them, the energy method calculates the inductance parameters by the magnetic field energy generated between the windings. However, for the special multi-winding situation of the double-current multi-winding traction transformer, its four Class I windings are connected in parallel internally. The size of the internal circulating current of the Class I winding cannot be determined during the calculation process using the energy method, which leads to certain calculation errors. Summary of the invention

[0004] As one of the key equipment of electric locomotive, it is very important to master the operating characteristics of the dual-current multi-winding traction transformer. The purpose of the embodiment of the present invention is to provide an equivalent circuit parameter calculation method for the dual-current multi-winding traction transformer, accurately establish an equivalent circuit model of the dual-current multi-winding traction transformer to accurately simulate and calculate the transformer response, and the model takes into account the influence of the internal circulating current of the winding to more accurately simulate the operating characteristics of the dual-current multi-winding traction transformer.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A method for calculating equivalent circuit parameters of a double-current multi-winding traction transformer, characterized in that it comprises the following steps:

[0007] Step 1: Full-scale proportional modeling of the dual-current multi-winding traction transformer is performed, and a finite element calculation model of the dual-current multi-winding traction transformer under two power supply systems of 25kV / 50Hz and 15kV / 16.7Hz is established;

[0008] Step 2: According to the finite element model, respectively calculate the 50 Hz inductance matrix and the 16.7 Hz inductance matrix formed between the class I winding coil1, the class II winding coil2 and the class III winding coil3 under the two power supply modes;

[0009] Step 3: Establish a 50Hz transformer multi-winding equivalent model and a 16.7Hz transformer multi-winding equivalent model based on the inductance matrix formed between the class I winding coil1, the class II winding coil2 and the class III winding coil3 under the two power supply modes;

[0010] Step 4: Considering the influence of the circulating current caused by the internal parallel connection of the Class I winding coil1, based on the 50Hz transformer multi-winding equivalent model and the 16.7Hz transformer multi-winding equivalent model, obtain the actual current sequence of each winding considering the circulating current under the short-circuit test between the Class I winding coil1 and the Class III winding coil3, between the Class I winding coil1 and the Class II winding coil2, and between the Class II winding coil2 and the Class III winding coil3 under two power supply systems;

[0011] Step 5: According to the actual current sequence of each winding, the short-circuit impedance between the Class I winding coil1 and the Class III winding coil3, between the Class I winding coil1 and the Class II winding coil2, and between the Class II winding coil2 and the Class III winding is calculated by the energy method, and the equivalent circuit parameters of the traction transformer are obtained.

[0012] In a preferred embodiment of the present invention, it also includes: the double-current multi-winding traction transformer; the double-current multi-winding traction transformer includes a Class I winding coil1, a Class II winding coil2 and a Class III winding coil3, wherein:

[0013] The double-current multi-winding traction transformer is composed of double-column 16 windings, which are class I winding coil1-1, class III winding coil3-1, class II winding coil2-11 and class II winding coil2-12 on the upper side of the left core column, class I winding coil1-2, class III winding coil3-2, class II winding coil2-21 and class II winding coil2-22 on the lower side of the left core column, class I winding coil1-3, class III winding coil3-3, class II winding coil2-31 and class II winding coil2-32 on the upper side of the right core column, class I winding coil1-4, class III winding coil3-4, class II winding coil2-41 and class II winding coil2-42 on the lower side of the right core column;

[0014] The class I winding coil1 consists of four windings connected in parallel and is used to connect to the grid side;

[0015] The class II winding coil2 is mainly divided into a 15kV class II winding coil2-a and a 25kV class II winding coil2-b, which are used to connect and feed to an AC-DC converter;

[0016] The 25kV Class II winding coil2-a is mainly composed of the Class II winding coil2-12, the Class II winding coil2-22, the Class II winding coil2-32 and the Class II winding coil2-42 close to the core, and are independent of each other.

[0017] The 15kV Class II winding coil2-b is mainly composed of the Class II winding coil2-11 and the Class II winding coil2-12 connected in series, the Class II winding coil2-21 and the Class II winding coil2-22 connected in series, the Class II winding coil2-31 and the Class II winding coil2-32 connected in series, and the Class II winding coil2-41 and the Class II winding coil2-42 connected in series, and they are independent of each other.

[0018] The class III winding coil3 consists of four windings connected in series, and is used to prevent class II side harmonics from entering the grid side.

[0019] In a preferred embodiment of the present invention, the 50 Hz inductance matrix and the 16.7 Hz inductance matrix are specifically: the matrix equation formula (1) between the current and flux linkage at 50 Hz through the transformer,

[0020]

[0021] Among them, ia(i=1,2,…,n) is the magnetic flux generated by each winding, and the diagonal element l ii (i=1,2,…,n) is the self-inductance of the i-th winding; the other off-diagonal elements represent the mutual inductance between two single windings;

[0022] The 50Hz inductance matrix formula of the double-current multi-winding traction transformer is obtained (2):

[0023]

[0024] Among them, M a is the transformer 50Hz inductance matrix, the diagonal element L ii (i=1,2,…,n) is the self-inductance of the i-th winding; the other off-diagonal elements represent the mutual inductance between two single windings;

[0025] Through the matrix equation formula (3) between current and flux linkage of double-current multi-winding traction transformer at 16.7Hz,

[0026]

[0027] Among them, ib (i=1,2,…,n) is the magnetic flux generated by each winding, and the diagonal element l ii (i=1,2,…,n) is the self-inductance of the i-th winding; the other off-diagonal elements represent the mutual inductance between two single windings;

[0028] The 16.7Hz inductance matrix formula of the double-current multi-winding traction transformer is obtained (4):

[0029]

[0030] Among them, M b is the transformer 16.7Hz inductance matrix, the diagonal element L ii (i=1, 2, ..., n) is the self-inductance of the i-th winding; the other non-diagonal elements represent the mutual inductance between two single windings.

[0031] In a preferred embodiment of the present invention, the 50Hz inductance matrix and the 16.7Hz inductance matrix are used to establish the 50Hz transformer multi-winding equivalent model and the 16.7Hz multi-winding equivalent model. Specifically,

[0032] Establishing a 50Hz multi-winding mutual inductance transformer model based on the 50Hz inductance matrix;

[0033] A 16.7 Hz multi-winding mutual inductance transformer model is established based on the 16.7 Hz inductance matrix.

[0034] In a preferred embodiment of the present invention, the 50Hz transformer multi-winding equivalent model and the 16.7Hz multi-winding equivalent model obtain the actual current sequence of the transformer considering the circulating current. Specifically, based on the 50Hz transformer multi-winding equivalent model, the class I winding coil1 is excited, the 25kV class II winding coil2-a is short-circuited separately, and the class III winding coil3 is open-circuited, and the 25kV class I to class II short-circuit current sequence is obtained:

[0035] [I coil1-1 ,I coil1-2 ,I coil1-3 ,I coil1-4 ,0,0,0,0,I coil2-a1 ,I coil2-a2 ,I coil2-a3 ,I coil2-a4 ]

[0036] Excitation is applied to the class I winding coil1, the class III winding coil3 is short-circuited, and the 25kV class II winding coil2-a is open-circuited, and a 25kV class I to class III short-circuit current sequence is obtained:

[0037] [I coil1-1 ,I coil1-2 ,I coil1-3 ,I coil1-4 ,I coil3 ,I coil3 ,I coil3 ,I coil3 ,0,0,0,0]

[0038] Excitation is applied to the class III winding coil3, the 25kV class II winding coil2-a is short-circuited individually, and the class I winding is connected in parallel without excitation, and the 25kV class III to class II short-circuit current sequence is obtained:

[0039] [I coil1-1 ,I coil1-2 ,I coil1-3 ,I coil1-4 ,I coil3 ,I coil3 ,I coil3 ,I coil3 ,I coil2-a1 ,I coil2-a2 ,I coil2-a3 ,I coil2-a4 ]

[0040] Based on the 16.7Hz transformer multi-winding equivalent model, the class I winding coil1 is excited, and the 25kV class II winding coil2-a is short-circuited separately, and the 15kV class I to class II short-circuit current sequence is obtained:

[0041] [I coil1-1 ,I coil1-2 ,I coil1-3 ,I coil1-4 ,0,0,0,0,I coil2-b1 ,I coil2-b2 ,I coil2-b3 ,I coil2-b4 ]

[0042] Excitation is applied to the class I winding coil1, and the class III winding coil3 is short-circuited, to obtain a 15 kV class I to class III short-circuit current sequence:

[0043] [I coil1-1 ,I coil1-2 ,I coil1-3 ,I coil1-4 ,I coil3 ,I coil3 ,I coil3 ,I coil3 ,0,0,0,0]

[0044] Excitation is applied to the class III winding coil3, and the 25kV class II winding coil2-a is short-circuited individually, to obtain a 15kV class III to class II short-circuit current sequence:

[0045] [I coil1-1 ,I coil1-2 ,I coil1-3 ,I coil1-4 ,I coil3 ,I coil3 ,I coil3 ,I coil3 ,I coil2-b1 ,I coil2-b2 ,I coil2-b3 ,I coil2-b4 ].

[0046] In a preferred embodiment of the present invention, the transformer takes into account the actual current sequence of the circulating current, and obtains the short-circuit impedance value between various windings of the transformer as follows:

[0047] The Class I winding coil1 is in parallel state at 25kV and 15kV. When excitation is applied on either side, there is a circulating current inside the Class I winding coil1, so that the current flowing through the Class I winding coil1-1, the Class I winding coil1-2, the Class I winding coil1-3 and the Class I winding coil1-4 inside the Class I winding coil1 is not balanced. The 25kV Class I to Class II short-circuit current sequence, the 25kV Class I to Class III short-circuit current sequence, and the 25kV Class III to Class II short-circuit current sequence are respectively substituted into the 25kV / 50Hz finite element calculation model of the traction transformer, and the 25kV Class I to Class II short-circuit impedance value Z is calculated using the back-substitution energy method. 12-25k , 25kV Class I to Class III short-circuit impedance value Z 13-25k And 25kV Class III to Class II short-circuit impedance value Z 32-25k The 15kV Class I to Class II short-circuit current sequence, the 15kV Class I to Class III short-circuit current sequence, and the 15kV Class III to Class II short-circuit current sequence are respectively substituted into the 15kV / 16.70Hz finite element calculation model of the traction transformer, and the 15kV Class I to Class II short-circuit impedance value Z is calculated by back substitution energy method. 12-15k , 15kV Class I to Class III short-circuit impedance value Z 13-15k And 15kV Class III to Class II short-circuit impedance value Z 32-15k .

[0048] In a preferred embodiment of the present invention, according to the relationship between the transformer equivalent circuit parameter and the short-circuit impedance value, it can be obtained that:

[0049] The equivalent circuit parameters of 25kV transformer are:

[0050]

[0051]

[0052]

[0053] Among them, Z 1-25k is the equivalent circuit parameter of Class I winding side of 25kV transformer multi-winding equivalent model; Z 3-25k is the equivalent circuit parameter of Class III winding side of 25kV transformer multi-winding equivalent model; Z 2-25k Equivalent circuit parameters of Class II winding side of 25kV transformer multi-winding equivalent model;

[0054] The equivalent circuit parameters of 15kV transformer are:

[0055]

[0056]

[0057]

[0058] Among them, Z 1-15k is the equivalent circuit parameter of Class I winding side of 15kV transformer multi-winding equivalent model; Z 3-15k is the equivalent circuit parameter of the Class III winding side of the 15kV transformer multi-winding equivalent model; Z 2-15k These are the equivalent circuit parameters of the Class II winding side of the 15kV transformer multi-winding equivalent model.

[0059] In a preferred embodiment of the present invention, the back-substitution energy method takes into account the influence of the internal circulating current of the Class I winding, and calculates the transformer equivalent circuit parameters by the energy method by solving the current distribution of the Class I winding and back-substituting it into the transformer finite element model.

[0060] The beneficial effects of the present invention are as follows

[0061] The present invention provides a method for calculating the equivalent circuit parameters of a dual-current multi-winding traction transformer, which can effectively solve the problem of insufficient accuracy and complex model of the equivalent circuit of the dual-current multi-winding traction transformer under different power supply systems. The modeling method fully considers the influence of the circulating current inside the winding, can simulate the operating characteristics of the transformer under different power supply systems, has wider applicability, is simple and effective, and has important guiding significance for transformer system simulation analysis and filter design. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 A flow chart of a method for calculating equivalent circuit parameters of a double-current multi-winding traction transformer provided by an embodiment of the present invention;

[0063] Figure 2 A schematic diagram of the winding arrangement of a double-current multi-winding traction transformer provided in an embodiment of the present invention;

[0064] Figure 3 A schematic diagram of an equivalent circuit model of a transformer in a method for calculating equivalent circuit parameters of a double-current multi-winding traction transformer provided in an embodiment of the present invention;

[0065] Explanation of symbols: Us-grid voltage, Z0-power supply side internal resistance, Z1-I type winding equivalent impedance, Z2-II type winding equivalent impedance, Z3-III type winding equivalent impedance, U S1 , U S2 , U S3 , U S4 - Four Class II winding output voltages. DETAILED DESCRIPTION

[0066] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0067] The present invention proposes a method for calculating equivalent circuit parameters of a double-current multi-winding traction transformer. The flow chart of the method is as follows: Figure 1 As shown, the following steps are included:

[0068] Step 1: Full-scale proportional modeling of a dual-current multi-winding traction transformer is performed, and a finite element calculation model of the traction transformer under two power supply systems of 25 kV / 50 Hz and 15 kV / 16.7 Hz is established;

[0069] Step 2, according to the finite element model, respectively calculating the 50 Hz inductance matrix and the 16.7 Hz inductance matrix formed between the class I winding coil1, the class II winding coil2 and the class III winding coil3 at 50 Hz and 16.7 Hz;

[0070] Step 3, establishing a 50Hz transformer multi-winding equivalent model and a 16.7Hz transformer multi-winding equivalent model based on the inductance matrix formed between the class I winding coil1, the class II winding coil2 and the class III winding coil3 at 50Hz and 16.7Hz;

[0071] Step 4, considering the influence of the circulating current caused by the internal parallel connection of the Class I winding coil1, based on the 50Hz transformer multi-winding equivalent model and the 16.7Hz transformer multi-winding equivalent model, the actual current sequence of each winding under the short-circuit test between the Class I winding coil1 and the Class III winding coil3, between the Class I winding coil1 and the Class II winding coil2, and between the Class II winding coil2 and the Class III winding under two power supply systems is obtained;

[0072] Step 5. According to the actual current values ​​of each winding, the energy method is used to calculate the short-circuit impedance between the Class I winding coil1 and the Class III winding, between the Class I winding coil1 and the Class II winding coil2, and between the Class II winding coil2 and the Class III winding coil3, and the equivalent circuit parameters of the dual-current multi-winding traction transformer are obtained according to the desired short-circuit impedance values.

[0073] Specifically, in step 1, the double-current multi-winding traction transformer is composed of a double-column twelve-winding, such as Figure 2As shown, they are Class I winding coil1-1, Class III winding coil3-1, Class II winding coil2-11 and Class II winding coil2-12 on the upper side of the left core column, Class I winding coil1-2, Class III winding coil3-2, Class II winding coil2-21 and Class II winding coil2-22 on the lower side of the left core column, Class I winding coil1-3, Class III winding coil3-3, Class II winding coil2-31 and Class II winding coil2-32 on the upper side of the right core column, and Class I winding coil1-4, Class III winding coil3-4, Class II winding coil2-41 and Class II winding coil2-42 on the lower side of the right core column.

[0074] Specifically, see Figure 2 , Figure 2 It is a schematic diagram of a double-column cross-section of a transformer structure in a method for calculating equivalent circuit parameters of a double-current multi-winding traction transformer provided in an embodiment of the present invention, wherein the Class I winding coil1 is composed of four windings, namely, the Class I winding coil1-1, the Class I winding coil1-2, the Class I winding coil1-3 and the Class I winding coil1-4, connected in parallel for connection to a power grid side;

[0075] The class II winding coil2 is mainly divided into a 15kV class II winding coil2-a and a 25kV class II winding coil2-b, which are used to connect and feed to an AC-DC converter;

[0076] The 25kV Class II winding coil2-a is mainly composed of the Class II winding coil2-12 close to the iron core, the Class II winding coil2-22, the Class II winding coil2-32 and the Class II winding coil2-42, and are independent of each other.

[0077] The 15kV Class II winding coil2-b is mainly composed of the Class II winding coil2-11 and the Class II winding coil2-12 connected in series, the Class II winding coil2-21 and the Class II winding coil2-22 connected in series, the Class II winding coil2-31 and the Class II winding coil2-32 connected in series, and the Class II winding coil2-41 and the Class II winding coil2-42 connected in series, and they are independent of each other.

[0078] The Class III winding consists of four windings connected in series, and is used to prevent Class II side harmonics from entering the grid side;

[0079] Specifically, in step 2, the 50 Hz inductance matrix and the 16.7 Hz inductance matrix are calculated, where:

[0080] The 50Hz inductance matrix is ​​obtained by the matrix equation between the current and flux linkage of the transformer at 50Hz.

[0081]

[0082] The transformer 50Hz inductance matrix formula (2) is obtained:

[0083]

[0084] The 16.7Hz inductance matrix is ​​obtained by the matrix equation between the current and flux linkage of the transformer at 16.7Hz.

[0085]

[0086] The transformer 16.7Hz inductance matrix formula (4) is obtained:

[0087]

[0088] Specifically, in step 4, the actual current sequence of the internal circulating current of the winding is considered, wherein,

[0089] A 50Hz multi-winding mutual inductance transformer model is established based on the 50Hz inductance matrix, and the class I winding coil1 is excited. The 25kV class II winding coil2-a is short-circuited separately, and the class III winding coil3 is open-circuited, and the 25kV class I to class II short-circuit current sequence is obtained:

[0090] [I coil1-1 ,I coil1-2 ,I coil1-3 ,I coil1-4 ,0,0,0,0,I coil2-a1 ,I coil2-a2 ,I coil2-a3 ,I coil2-a4 ]

[0091] Excitation is applied to the class I winding coil1, the class III winding coil3 is short-circuited, and the 25kV class II winding coil2-a is open-circuited, and a 25kV class I to class III short-circuit current sequence is obtained:

[0092] [I coil1-1 ,I coil1-2 ,I coil1-3 ,I coil1-4 ,I coil3 ,I coil3 ,I coil3 ,I coil3 ,0,0,0,0]

[0093] Excitation is applied to the Class III winding F, the 25kV Class II winding coil2-a is short-circuited individually, and the Class I winding is connected in parallel without excitation, and the 25kV Class III to Class II short-circuit current sequence is obtained:

[0094] [I coil1-1 ,I coil1-2 ,I coil1-3 ,I coil1-4 ,I coil3 ,I coil3 ,I coil3 ,I coil3 ,I coil2-a1 ,I coil2-a2 ,I coil2-a3 ,I coil2-a4 ]

[0095] A 16.7 Hz multi-winding mutual inductance transformer model is established based on the 16.7 Hz inductance matrix, and the class I winding coil1 is excited. The 25 kV class II winding coil2-a is short-circuited separately to obtain a 15 kV class I to class II short-circuit current sequence:

[0096] [I coil1-1 ,I coil1-2 ,I coil1-3 ,I coil1-4 ,0,0,0,0,I coil2-b1 ,I coil2-b2 ,I coil2-b3 ,I coil2-b4 ]

[0097] Excitation is applied to the class I winding coil1, and the class III winding coil3 is short-circuited, to obtain a 15 kV class I to class III short-circuit current sequence:

[0098] [I coil1-1 ,I coil1-2 ,I coil1-3 ,I coil1-4 ,I coil3 ,I coil3 ,I coil3 ,I coil3 ,0,0,0,0]

[0099] The class III winding coil3 is excited, and the 25kV class II winding coil2-a is short-circuited separately, and a 15kV class III to class II short-circuit current sequence is obtained:

[0100] [I coil1-1 ,I coil1-2 ,I coil1-3 ,I coil1-4 ,I coil3 ,I coil3,I coil3 ,I coil3 ,I coil2-b1 ,I coil2-b2 ,I coil2-b3 ,I coil2-b4 ]

[0101] The Class I winding coil1 is in parallel state at 25kV and 15kV. When excitation is applied on either side, there is a circulating current inside the Class I winding coil1, so that the current flowing through the Class I winding 1, the Class I winding 2, the Class I winding 3 and the Class I winding 4 inside the Class I winding coil1 is not balanced. The 25kV Class I to Class II short-circuit current sequence, the 25kV Class I to Class III short-circuit current sequence, and the 25kV Class III to Class II short-circuit current sequence are respectively substituted into the 25kV / 50Hz finite element calculation model of the traction transformer, and the 25kV Class I to Class II short-circuit impedance value Z is calculated using the back-substitution energy method. 12-25k , 25kV Class I to Class III short-circuit impedance value Z 13-25k And 25kV Class III to Class II short-circuit impedance value Z 32-25k The 15kV Class I to Class II short-circuit current sequence, the 15kV Class I to Class III short-circuit current sequence, and the 15kV Class III to Class II short-circuit current sequence are respectively substituted into the 15kV / 16.70Hz finite element calculation model of the traction transformer, and the 15kV Class I to Class II short-circuit impedance value Z is calculated by back substitution energy method. 12-15k , 15kV Class I to Class III short-circuit impedance value Z 13-15k And 15kV Class III to Class II short-circuit impedance value Z 32-15k .

[0102] Specifically, in step 5, further, the transformer equivalent circuit parameters, wherein,

[0103] The equivalent circuit parameters of 25kV transformer are:

[0104]

[0105]

[0106]

[0107] Among them, Z 1-25k is the equivalent circuit parameter of Class I winding side of 25kV transformer multi-winding equivalent model; Z 3-25k is the equivalent circuit parameter of Class III winding side of 25kV transformer multi-winding equivalent model; Z 2-25k These are the equivalent circuit parameters of the Class II winding side of the multi-winding equivalent model of a 25kV transformer.

[0108] The equivalent circuit parameters of 15kV transformer are:

[0109]

[0110]

[0111]

[0112] Among them, Z 1-15k is the equivalent circuit parameter of Class I winding side of 15kV transformer multi-winding equivalent model; Z 3-15k is the equivalent circuit parameter of the Class III winding side of the 15kV transformer multi-winding equivalent model; Z 2-15k These are the equivalent circuit parameters of the Class II winding side of the 15kV transformer multi-winding equivalent model.

[0113] Thus, the equivalent circuit model of the double-current multi-winding transformer can be obtained, as shown in Figure 3 As shown in the figure, Z1 is the equivalent impedance of Class I winding, which is equal to Z under 25kV / 50Hz and 15kV / 16.7Hz traction power supply system respectively. 1-25k With Z 1-15k ; Z2 is the equivalent impedance of Class II winding, which is equal to Z under 25kV / 50Hz and 15kV / 16.7Hz traction power supply system respectively. 2-25k With Z 2-15k ; Z3 is the equivalent impedance of Class III winding, which is equal to Z under 25kV / 50Hz and 15kV / 16.7Hz traction power supply system respectively. 3-25k With Z 3-15k .

[0114] The present invention provides a method for calculating the equivalent circuit parameters of a dual-current multi-winding traction transformer, which can effectively solve the problem of insufficient accuracy and complex model of the equivalent circuit model of the dual-current multi-winding traction transformer under different power supply systems. The modeling method fully considers the influence of the circulating current inside the winding, can simulate the operating characteristics of the transformer under different power supply systems, has a wider applicability, avoids the complexity of model replacement, is simple and effective, and has important guiding significance for transformer electromagnetic transient analysis and filter design.

[0115] The above is only a description of the preferred implementation of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. Those skilled in the art of the present invention may make various modifications or supplements to the specific embodiments described or replace them in a similar manner without departing from the spirit and principle of the present invention, which shall be deemed as the protection scope of the present invention.

Claims

1. A method for calculating equivalent circuit parameters of a double-current multi-winding traction transformer, characterized in that: The steps include: Step 1: Full-scale proportional modeling of the dual-current multi-winding traction transformer is performed, and a finite element calculation model of the dual-current multi-winding traction transformer under two power supply systems of 25kV / 50Hz and 15kV / 16.7Hz is established; Step 2: According to the finite element model, the 50Hz inductance matrix and the 16.7Hz inductance matrix formed between the class I winding coil1, the class II winding coil2 and the class III winding coil3 under the two power supply systems are calculated respectively, and a 50Hz transformer multi-winding equivalent model and a 16.7Hz transformer multi-winding equivalent model are established; Step 3: Considering the influence of the circulating current caused by the internal parallel connection of the Class I winding coil1, based on the 50Hz transformer multi-winding equivalent model and the 16.7Hz transformer multi-winding equivalent model, obtain the actual current sequence of each winding considering the circulating current under the short-circuit test between the Class I winding coil1 and the Class III winding coil3, between the Class I winding coil1 and the Class II winding coil2, and between the Class II winding coil2 and the Class III winding coil3 under two power supply systems; Step 4: According to the actual current sequence of each winding, the short-circuit impedance between the Class I winding coil1 and the Class III winding coil3, between the Class I winding coil1 and the Class II winding coil2, and between the Class II winding coil2 and the Class III winding is calculated by the energy method, and the equivalent circuit parameters of the traction transformer are obtained.

2. The method for calculating equivalent circuit parameters of a double-current multi-winding traction transformer according to claim 1 is characterized in that: include: The double-current multi-winding traction transformer; the double-current multi-winding traction transformer includes a Class I winding coil1, a Class II winding coil2 and a Class III winding coil3, wherein: The double-current multi-winding traction transformer is composed of double-column 16 windings, which are class I winding coil1-1, class III winding coil3-1, class II winding coil2-11 and class II winding coil2-12 on the upper side of the left core column, class I winding coil1-2, class III winding coil3-2, class II winding coil2-21 and class II winding coil2-22 on the lower side of the left core column, class I winding coil1-3, class III winding coil3-3, class II winding coil2-31 and class II winding coil2-32 on the upper side of the right core column, class I winding coil1-4, class III winding coil3-4, class II winding coil2-41 and class II winding coil2-42 on the lower side of the right core column; The class I winding coil1 consists of four windings connected in parallel and is used to connect to the grid side; The class II winding coil2 is mainly divided into a 15k class VII winding coil2-a and a 25k class VII winding coil2-b, which are used to connect and feed to an AC-DC converter; Among them, the 25k Class VII winding coil2-a is mainly composed of the Class II winding coil2-12 close to the core, the Class II winding coil2-22, the Class II winding coil2-32 and the Class II winding coil2-42, and are independent of each other; The 15kVII class winding coil2-b is mainly composed of the class II winding coil2-11 and the class II winding coil2-12 connected in series, the class II winding coil2-21 and the class II winding coil2-22 connected in series, the class II winding coil2-31 and the class II winding coil2-32 connected in series, and the class II winding coil2-41 and the class II winding coil2-42 connected in series, and they are independent of each other. The class III winding coil3 consists of four windings connected in series, and is used to prevent class II side harmonics from entering the grid side.

3. The method for calculating equivalent circuit parameters of a double-current multi-winding traction transformer according to claim 2 is characterized in that: The 50Hz inductance matrix and the 16.7Hz inductance matrix are specifically: the matrix equation formula (1) between the current and flux linkage at 50Hz through the transformer, Among them, ia (i=1,2,…,n) is the magnetic flux generated by each winding, and the diagonal element l ii (i=1,2,…,n) is the self-inductance of the i-th winding; the other off-diagonal elements represent the mutual inductance between two single windings; The 50Hz inductance matrix formula of the double-current multi-winding traction transformer is obtained (2): Among them, M a is the transformer 50Hz inductance matrix, the diagonal element L ii (i=1,2,…,n) is the self-inductance of the i-th winding; the other off-diagonal elements represent the mutual inductance between two single windings; Through the matrix equation formula (3) between current and flux linkage of double-current multi-winding traction transformer at 16.7Hz, Among them, ib (i=1,2,…,n) is the magnetic flux generated by each winding, and the diagonal element l ii (i=1,2,…,n) is the self-inductance of the i-th winding; the other off-diagonal elements represent the mutual inductance between two single windings; The 16.7Hz inductance matrix formula of the double-current multi-winding traction transformer is obtained (4): Among them, M b is the transformer 16.7Hz inductance matrix, the diagonal element L ii (i=1, 2, ..., n) is the self-inductance of the i-th winding; the other non-diagonal elements represent the mutual inductance between two single windings.

4. The method for calculating equivalent circuit parameters of a double-current multi-winding traction transformer according to claim 3 is characterized in that: The 50Hz inductance matrix and the 16.7Hz inductance matrix are used to establish the 50Hz transformer multi-winding equivalent model and the 16.7Hz transformer multi-winding equivalent model. Specifically, the 50Hz transformer multi-winding equivalent model and the 16.7Hz transformer multi-winding equivalent model are: A 50Hz multi-winding mutual inductance transformer model is established based on the 50Hz inductance matrix, and the class I winding coil1 is excited. The 25k class VII winding coil2-a is short-circuited separately, and the class III winding coil3 is open-circuited, and the 25k class Vl to class II short-circuit current sequence is obtained: [I coil1-1 ,I coil1-2 ,I coil1-3 ,I coil1-4 ,0,0,0,0,I coil2-a1 ,I coil2-a2 ,I coil2-a3 ,I coil2-a4 ] Excitation is applied to the class I winding coil1, the class III winding coil3 is short-circuited, and the 25k class VII winding coil2-a is open-circuited, and the 25k class VI to class III short-circuit current sequence is obtained: [I coil1-1 ,I coil1-2 ,I coil1-3 ,I coil1-4 ,I coil3 ,I coil3 ,I coil3 ,I coil3 ,0,0,0,0] Excitation is applied to the Class III winding coil3, the 25kV Class VII winding coil2-a is short-circuited individually, and the Class I winding is connected in parallel without excitation, and the 25kV Class III to Class II short-circuit current sequence is obtained: [I coil1-1 ,I coil1-2 ,I coil1-3 ,I coil1-4 ,I coil3 ,I coil3 ,I coil3 ,I coil3 ,I coil2-a1 ,I coil2-a2 ,I coil2-a3 ,I coil2-a4 ] A 16.7Hz multi-winding mutual inductance transformer model is established based on the 16.7Hz inductance matrix, and the class I winding coil1 is excited. The 25k class VII winding coil2-a is short-circuited separately, and the 15k class VI to class II short-circuit current sequence is obtained: [I coil1-1 ,I coil1-2 ,I coil1-3 ,I coil1-4 ,0,0,0,0,I coil2-b1 ,I coil2-b2 ,I coil2-b3 ,I coil2-b4 ] Excitation is applied to the class I winding coil1, and the class III winding coil3 is short-circuited, to obtain a 15kV class I to class III short-circuit current sequence: [I coil1-1 ,I coil1-2 ,I coil1-3 ,I coil1-4 ,I coil3 ,I coil3 ,I coil3 ,I coil3 ,0,0,0,0] Excitation is applied to the Class III winding coil3, and the 25kV Class VII winding coil2-a is short-circuited individually, to obtain a 15kV Class III to Class II short-circuit current sequence:

5. The method for calculating equivalent circuit parameters of a double-current multi-winding traction transformer according to claim 4 is characterized in that: The actual current sequence of the transformer considering the circulating current is obtained by using the 50Hz transformer multi-winding equivalent model and the 16.7Hz transformer multi-winding equivalent model: The Class I winding coil1 is in parallel state at 25kV and 15kV. When excitation is applied on either side, there is a circulating current inside the Class I winding coil1, so that the current flowing through the Class I winding coil1-1, the Class I winding coil1-2, the Class I winding coil1-3 and the Class I winding coil1-4 inside the Class I winding coil1 is not balanced. The 25kV Class I to Class II short-circuit current sequence, the 25kV Class I to Class III short-circuit current sequence, and the 25kV Class III to Class II short-circuit current sequence are respectively substituted into the 25kV / 50Hz finite element calculation model of the traction transformer, and the back-substitution energy method is used to calculate the 25kV Class I to Class II short-circuit impedance value Z 12-25k 、25kV Class VI to Class III short-circuit impedance value Z 13-25k And 25kV Class III to Class II short-circuit impedance value Z 32-25k Substitute the 15kV class VI to class II short-circuit current sequence, the 15kV class VI to class III short-circuit current sequence, and the 15kV class III to class II short-circuit current sequence into the traction transformer 15kV / 16.70Hz finite element calculation model, and use the back substitution energy method to calculate the 15kV class VI to class II short-circuit impedance value Z 12-15k 、15kV Class VI to Class III short-circuit impedance value Z 13-15k And 15kV Class III to Class II short-circuit impedance value Z 32-15k .

6. The method for calculating equivalent circuit parameters of a dual-current multi-winding traction transformer according to claim 5 is characterized in that: According to the relationship between the transformer equivalent circuit parameters and the short-circuit impedance value, we can get: The equivalent circuit parameters of 25kV transformer are: Among them, Z 1-25k is the equivalent circuit parameter of Class I winding side of 25kV transformer multi-winding equivalent model; Z 3-25k is the equivalent circuit parameter of Class III winding side of 25kV transformer multi-winding equivalent model; Z 2-25k Equivalent circuit parameters of Class II winding side of 25kV transformer multi-winding equivalent model; The equivalent circuit parameters of 15kV transformer are: Among them, Z 1-15k is the equivalent circuit parameter of Class I winding side of 15kV transformer multi-winding equivalent model; Z 3-15k is the equivalent circuit parameter of the Class III winding side of the 15kV transformer multi-winding equivalent model; Z 2-15k These are the equivalent circuit parameters of the Class II winding side of the 15kV transformer multi-winding equivalent model.

7. The method for calculating equivalent circuit parameters of a dual-current multi-winding traction transformer according to claim 6 is characterized in that: The back-substitution energy method considers the influence of the internal circulating current of the Class I winding, and calculates the transformer equivalent circuit parameters by the energy method by solving the current distribution of the Class I winding and back-substituting it into the transformer finite element model.

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