阅读说明：本技术 一种阻抗平衡的多绕组变压器供电系统 (Multi-winding transformer power supply system with balanced impedance ) 是由 陆亦辰 赵道德 李哲 陈林 张秀娟 陈邦栋 谢伟 葛洲 杨莹冰 于 2021-08-10 设计创作，主要内容包括：本发明属于电力设备的技术领域,公开了一种阻抗平衡的多绕组变压器供电系统,应用于城市轨道交通地铁,包括两台结构相同的多绕组变压器,它们并联在一起,其高压端连接外部电网,其中一台多绕组变压器低压端通过整流模块连接至为地铁供电的低压电网,其能馈绕组空置不用或者由绝缘支撑件替代,另一台多绕组变压器低压端分接整流模块和能馈模块连接至为地铁供电的低压电网。本发明的整体结构简单,实现方便,成本低廉。(The invention belongs to the technical field of power equipment, and discloses an impedance-balanced multi-winding transformer power supply system, which is applied to urban rail transit subways and comprises two multi-winding transformers with the same structure, wherein the multi-winding transformers are connected in parallel, the high-voltage ends of the multi-winding transformers are connected with an external power grid, the low-voltage end of one multi-winding transformer is connected to a low-voltage power grid for supplying power to the subways through a rectifier module, a feed winding of the multi-winding transformer is not used or is replaced by an insulating support piece, and the low-voltage end of the other multi-winding transformer is connected with a tapping rectifier module and a feed module and is connected to the low-voltage power grid for supplying power to the subways. The invention has simple integral structure, convenient realization and low cost.)

1. An impedance balanced multi-winding transformer power supply system, characterized by: the low-voltage end of one multi-winding transformer is connected with a low-voltage power grid supplying power to the subway through a rectification module, a feed winding of the multi-winding transformer is not used or is replaced by an insulating support piece, and the low-voltage end of the other multi-winding transformer is connected with the low-voltage power grid supplying power to the subway through the rectification module and the feed module respectively.

2. The impedance-balanced, multi-winding transformer power supply system of claim 1, wherein: the two multi-winding transformers are respectively marked as T₁And T₂In which a multi-winding transformer T₁Comprising a high-voltage side winding, two low-voltage side windings and a free energy-feeding winding, or a high-voltage side winding, two low-voltage side windings andan insulating support member; multi-winding transformer T₂The high-voltage side winding and the low-voltage side winding are connected with the energy feed winding.

3. The impedance-balanced, multi-winding transformer power supply system of claim 2, wherein: the energy feed winding adopts an angle connection or star connection structure.

Technical Field

The invention relates to the technical field of electrical equipment, in particular to a multi-winding transformer power supply system with balanced impedance.

Background

In the field of subway traction power supply, two 12-phase rectifier transformers with 30-degree phase shift are generally adopted to step down and supply power to a traction rectifier, an equivalent 24-pulse direct current power supply system is formed after rectification, the capacities and the structural types of primary and secondary windings of the two transformers are identical, the difference is that the phase shift angles of the primary winding are respectively +7.5 degrees and-7.5 degrees, the number of turns of the phase shift windings of the two rectifier transformers is also identical, and the impedance voltage of the transformer is determined by the number of turns of the windings and the structural size, so that the impedance voltage of the two rectifier transformers can be kept identical.

In order to meet the requirement of train braking energy recovery, a new multi-winding transformer needs to add an energy feed winding on the basis of the original 12-phase rectifier transformer with the same capacity, and after the energy feed winding is added, the overall structure of the transformer is changed, the impedance of the rectifier winding of the multi-winding transformer is difficult to keep the same as that of the original 12-phase rectifier transformer, and in some occasions, the multi-winding transformer and the 12-phase rectifier transformer need to be connected into the rectifier and then connected in parallel for power supply, so that the output power of two groups of power supplies after rectification is unbalanced.

Disclosure of Invention

The invention provides an impedance-balanced multi-winding transformer power supply system, which solves the problems of unbalanced output power and the like caused by different structures of two transformers in the conventional power supply system.

The invention can be realized by the following technical scheme:

the utility model provides an impedance balance's multi-winding transformer power supply system, is applied to urban rail transit subway, includes two multi-winding transformers that the structure is the same, and they connect together in parallel, and its high-voltage terminal connects external electric wire netting, and wherein the low-voltage terminal of one of them multi-winding transformer is connected to the low-voltage electric wire netting for subway power supply through rectifier module, and it can feed the winding and do not leave the vacancy or replace by insulating support piece, and the low-voltage terminal of another multi-winding transformer is connected to the low-voltage electric wire netting for subway power supply through rectifier module and can feed the module respectively.

Further, two of the combined transformers are respectively marked as T₁And T₂In which a multi-winding transformer T₁The transformer comprises a high-voltage side winding, two low-voltage side windings and a vacant energy feed winding, or the high-voltage side winding, the two low-voltage side windings and an insulating support; multi-winding transformer T₂The high-voltage side winding and the low-voltage side winding are connected with the energy feed winding.

Furthermore, the energy feed winding adopts an angle connection or star connection structure.

The beneficial technical effects of the invention are as follows:

the 12-phase rectifier transformer is designed to be completely the same as the multi-winding transformer or the insulating support member is used for replacing an energy feed winding which is lacked in the 12-phase rectifier transformer and is compared with the multi-winding transformer, so that the overall structures of the two transformers can be ensured to be the same, the impedance balance between the two transformers is further ensured, and the problem of unbalanced impedance of the rectifier winding caused by the additional arrangement of the energy feed winding is solved. The invention can be popularized to transformer power supply systems with different winding numbers and balanced main winding impedance.

Drawings

FIG. 1 is a schematic diagram of a 24-pulse rectification power supply system in the prior art;

FIG. 2 is a schematic diagram of a prior art power supply system with a 12-phase rectifier transformer and a multi-winding transformer connected in parallel;

FIG. 3 is a schematic cross-sectional view of a transformer winding configuration for calculating the relative impedance of a split transformer;

FIG. 4 is the transformer T in FIG. 2₁A schematic cross-sectional view of a winding structure;

FIG. 5 is the transformer T in FIG. 2₂A schematic cross-sectional view of a winding structure;

fig. 6 is a schematic diagram of a power supply system according to a first embodiment of the present invention;

FIG. 7 shows a transformer T according to a second embodiment of the present invention₁And the cross section of the winding structure is schematic.

Detailed Description

The following detailed description of the preferred embodiments will be made with reference to the accompanying drawings.

In the field of subway traction power supply, two 12-phase wave rectifier transformers T are generally adopted as shown in figure 1₁、T₂The step-down power supply forms an equivalent 24-pulse direct current power supply system for a traction rectifier, and a transformer in a subway traction power supply system usually adopts a split transformer structure, wherein X is₁Is a high-voltage side winding, X₂、X₃Is a low voltage side winding. In order to meet the requirement of train braking energy recovery, a novel multi-winding transformer T is shown in figure 2₂An energy feed winding needs to be added on the basis of the original 12-phase rectifier transformer with the same capacity, namely X in figure 2₄Winding, X₄The windings can be connected in an angle or star connection mode.

The proportion of the reactance component in the impedance of the transformer is large, and as the capacity of the transformer increases, the proportion increases. In large transformers, it is quite possible to replace the impedance value with a reactance value, and the reactance calculation formula of the split transformer will be described below by taking fig. 3 as an example.

As shown in FIG. 3, X₁、X₂Is a high-voltage side winding, X₃、X₄Is a low voltage side winding, B_q1、B_q2、B_q3、B_q4The radial dimension of each coil, A₁₃、A₂₄For the main gap dimension between each pair of coils, H_kIs average reactance height, λ is leakage width, R_p1、R_p2、R_p3、R_p4Is the average radius of each coil, R_p13、R_p24Is the mean radius of each main channel, D₀Is the core diameter and s' is the distance from the core to the low voltage winding.

The reactance height expression is then:

the magnetic leakage width expression is as follows:

λ＝λ₁₃＝λ₂₄＝B_q1+A₁₃+B_q3 (3)

λ_s12＝B_q1＝B_q2 (4)

λ_s34＝B_q3＝B_q4 (5)

the expression of the Rockwell coefficient is as follows:

in formulae (6) to (9), u_s12＝λ_s12/H_k12，u_s34＝λ_s34/H_k34，v₁₂＝(s'+D₀+B_q3+A₁₃)/H_k12，v₃₄＝(s'+D₀)/H_k34，u₁₃＝u₂₄＝H_k13/λ₁₃＝H_k24/λ₂₄，u＝H_k/λ。

Then the transformerEquivalent total area sigma D of leakage flux_RThe expression of (a) is:

when the number of turns of the line segment and the oil passages between the segments are uniformly distributed:

wherein, B_t1、B_t2、B_t3、B_t4Is the height of the high voltage 1, 2 and the low voltage 3, 4 line segments, n_g1、n_g2、n_g3、n_g4High voltage 1, 2 and low voltage 3, 4 line segment numbers, h_dy1、h_dy2、h_dy3、h_dy4Oil passages between high pressure 1, 2 and low pressure 3, 4 line sections.

The reactance of each pair of windings is expressed as:

wherein f is the rated frequency, I₁W₁、I₂W₂For each ampere turn of the phase to be tapped, K_xAs a reactance correction factor, e_tFor each turn of potential.

When two low-voltage windings are connected in parallel, the short-circuit reactance between the high-voltage winding and the low-voltage winding is throughThe more reactance X_k%, its expression is:

when one of the two low-voltage windings is open-circuited, the other low-voltage winding has a half-through reactance X to the short-circuit reactance between the high-voltage windings_B%, its expression is:

from the combination of the equations (1) to (17), it can be seen that when the current, the number of winding turns, and the coil parameters are the same, the short-circuit reactance X between the high and low voltage windings of the transformer is the same_k％、X_B% is related only to the winding structure size.

For the power supply system with energy recovery function as shown in fig. 2, the transformer T₁The winding structure of a 12-phase rectifier transformer is shown in fig. 4, and compared with the example of fig. 3 for calculating the relevant reactance of the transformer, the difference of fig. 4 is that a lead wire for showing the wiring mode of the winding is added, and X in fig. 4_{1_1}And X_{1_2}Parallel connection constitutes the transformer T in FIG. 2₁High-voltage side winding X₁，X₂And X₃Two low voltage side windings. From the transformer structure point of view, X in FIG. 4_{1_1}Corresponding to X in FIG. 3₁X in FIG. 4_{1_2}Corresponding to X in FIG. 3₂X in FIG. 4₂Corresponding to X in FIG. 3₃X in FIG. 4₃Corresponding to X in FIG. 3₄. Transformer T₂The winding structure of the multi-winding transformer with the energy-fed windings is shown in figure 5. As can be seen from FIGS. 4 and 5, due to the transformer T₂An energy feed winding X is added₄(X₄The windings can be connected in angle or star), so that the transformer T can be connected₂Winding X of₂、X₃Distance to core compared to transformer T₁Changed due to the difference of winding structures, the transformer T₁、T₂Is difficult to balance, and the impedance is difficult to balance in practical applicationThe unbalance degree is more than or equal to 10 percent, which causes the unbalance of the output power of the two groups of power supplies after rectification.

The invention provides an impedance-balanced multi-winding transformer power supply system, which comprises two multi-winding transformers with the same structure, wherein the two multi-winding transformers are connected in parallel, the high-voltage ends of the two multi-winding transformers are connected with an external power grid, the low-voltage end of one multi-winding transformer is connected to a low-voltage power grid for supplying power to a subway through a rectifying module, a feed winding of the multi-winding transformer is not vacant or is replaced by an insulating support piece, and the low-voltage end of the other multi-winding transformer is connected to the low-voltage power grid for supplying power to the subway through the rectifying module and the feed module respectively. The method can be realized by the following technical scheme:

the first scheme is as follows: transformer T in fig. 2₁Designed to be connected to a transformer T₂The same multi-winding transformer, as shown in FIG. 6, is transformer T in operation₁Energy-fed winding X₄(X₄The windings can be connected in an angle or star connection) and are not used. Transformer T in FIG. 6₁、T₂The main winding impedance of the two transformers can be kept consistent because the main winding impedance of the transformers is determined by the number of winding turns and the structural size. The scheme is simple and easy to implement, and has the defect that the energy feed winding is vacant without waste.

Scheme II: transformer T in fig. 2₁The design is to use an insulating support to replace the energy feeding winding, the winding structure is shown in fig. 7, the original energy feeding winding is replaced by the insulating support, as shown by the shaded part in fig. 7, and the transformer T₂The winding structure shown in fig. 5 is still used.

Because the transformer is a concentric structure with the iron core in the middle and the other windings wound around the iron core from inside to outside in sequence, the calculation of the impedance of the transformer shows that when the flowing current, the number of turns of the windings and the coil parameters are the same, the short-circuit reactance between the high-voltage windings and the low-voltage windings of the transformer is only related to the size of the winding structure. The definition of the insulating support in fig. 7 is therefore required to guarantee the iron core to X in fig. 7₂、X₃Distance of winding from iron core to X in FIG. 5₂、X₃The distance of the windings being the same, i.e. d in FIG. 7_core23And d in FIG. 5_core23Are identical to each other。

Due to the transformer T₁And T₂X of (2)₁～X₃The winding structure is of the same size, so long as d in FIG. 7 is guaranteed_core23And d in FIG. 5_core23In the same way, the transformer T having the structure shown in FIG. 7 can be ensured₁And a transformer T having a structure as shown in FIG. 5₂The winding structure is the same size. When some occasions need to use the multi-winding transformer T₂And 12-phase rectifier transformer T₁When the two transformers are connected in parallel for power supply after rectification, the number of turns and the structure of the windings of the two transformers in the connected system are the same, so that the impedance balance between the two transformers is ensured, and the problem of unbalanced impedance of the rectification windings caused by the arrangement of the energy feedback windings is solved.

Although specific embodiments of the present invention have been described above, it will be appreciated by those skilled in the art that these are merely examples and that many variations or modifications may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is therefore defined by the appended claims.