CN105225805A - T wiring balancing transformer - Google Patents

Abstract

The invention provides a kind of T wiring balancing transformer, this transformer comprises a T wiring transformer and a step-up auto-transformer, and it is characterized in that T wiring transformer first side winding adopts the wiring of Y type, its neutral point allows ground connection, and the first side winding number of turn is W ₁; In secondary side winding, A phase winding is made up of ao, ob two windings, and B, C phase winding is respectively bc, ca winding; Bc and ca umber of turn is W ₂, ao and ob umber of turn is 0.5W ₂, ao and ob winding is that points of common connection connects into ab winding with o, and ab, bc and ca winding is connected into triangle.C with o is connected a no-load voltage ratio step-up auto-transformer, form T wiring balancing transformer.Output voltage U _ab, U _fheffective value is equal, and phase 90 °.T wiring balancing transformer winding construction is simple, capacity utilization and stock utilization high, manufacture difficulty is low.

Description

T wiring balancing transformer

Technical field

The invention belongs to balancing transformer technical field, relate to a kind of three-phase to two phase balance transformer.

Background technology

What the electric power system of China adopted is three-phase alternating current system, but some special user needs two-phase or single phase power supply power supply, and this can cause the asymmetric operation of three-phase system and serious negative phase-sequence problem.Electric railway traction power supply system is exactly special two-phase electric power system, and the method solving tractive power supply system negative phase-sequence problem is at present that traction transformer adopts the three-phase to two phase balance mode of connection.Current equilibrium at home and abroad transformer connection mode mainly contains Scott wiring, LeBlanc wiring or Woodbridge wiring three kinds of citation forms.

Scott wiring transformer high-pressure side can not be drawn neutral ground and be run, and stock utilization and capacity utilization are not high, and low-pressure side does not have triangle loop yet, therefore contains third-harmonic component in voltage, causes serious Communication Jamming.

LeBlanc wiring transformer primary side is connected into triangle, eliminate the impact of third-harmonic flux, but high-pressure side does not have neutral point, need to design by all insulation, add cost, when powering for electric railway AT, because low-pressure side two-phase does not have common point, need increase by two capacity to be the autotransformer of main transformer capacity half, overall investment increases.

Woodbridge wiring transformer neutral point can direct ground connection, and high pressure winding can design by graded insulation, has triangle loop in low-pressure side, but low-pressure side two-phase occurs without common point, needs two autotransformers, and this is also larger adds equipment investment.

Domestic balancing transformer mainly balanced impedance matching transformer, balanced impedance matching transformer high-pressure side neutral point can direct ground connection, and low-pressure side has triangle loop, and two-phase outlet has common point to draw to connect rail.But the winding impedance of balanced impedance matching transformer coupling is more difficult, need artificially a phase (or c phase) low pressure winding to be split, to meet the matching relationship of equivalent impedance, b phase two prolongs limit low pressure winding need do arranged crosswise, and require that coupling closely, to reduce influencing each other of two limit windings, therefore winding construction is complicated.If for AT power-supply service, then in b phase iron core column by layout 7 windings, i.e. a high pressure winding, 6 low pressure windings.All to make arranged crosswise for 4 in low pressure winding, make design to be difficult to realize.So balanced impedance matching transformer can only be used for direct-furnish and BT supply power mode.

The main flow supply power mode of current electric railway traction power supply system is AT supply power mode, and requires two-phase or three-phase windings symmetry for balancing transformer, and this brings difficulty to production enforcement.

Summary of the invention

Technical problem to be solved by this invention proposes a kind of wiring simply, the three-phase to two phase balance transformer mode of connection that winding symmetry is good.This mode of connection structure is simple, and stock utilization is high, and it is little that difficulty is implemented in production, and be applicable to AT power supply system of electrified railway.

Technical scheme of the present invention is as follows:

A kind of T wiring balancing transformer, comprises a T wiring three phase transformation two-phase transformer and a no-load voltage ratio is step-up auto-transformer, in T wiring three phase transformation two-phase Circuit Fault on Secondary Transformer two-phase one is connected step-up auto-transformer.Wherein the mode of connection of T wiring three phase transformation two-phase transformer is core of the present invention, and T wiring three phase transformation two-phase transformer comprises iron core, first side winding and secondary side winding.Iron core is three-phase pillar iron core or three-phase shell type core.First side winding adopts the wiring of Y type, and neutral point N allows ground connection, and the first side winding number of turn is W ₁.

Secondary side winding is delta connection.A phase winding is made up of ao and ob two windings, and B phase winding is bc winding, and C phase winding is ca winding.Ao and ob umber of turn is 0.5W ₂, bc and ca umber of turn is W ₂.Two winding ao and ob of A phase are points of common connection with o, are connected to become ab winding.Ab, bc and ca tri-windings respectively with a, b, c for points of common connection is connected into triangle, draw a, b, c, o tetra-voltage output ends.Wherein a, b output output voltage U _ab, c, o output output voltage U _co.The mode of connection described above forms the mode of connection of T wiring three phase transformation two-phase transformer.Export two phase voltages of phase 90 °, and output voltage effective value relation is shown below:

$U_{\mathrm{co}}=\frac{\sqrt{3}}{2}{U}_{\mathrm{ab}}---\left(1\right)$

The two-phase voltage effective value that T wiring three phase transformation two-phase transformer exports varies in size, therefore U _coneed through a no-load voltage ratio be step-up auto-transformer voltage is risen to and U _abeffective value size is identical.Output voltage after boosting is as U _α, U _abas output voltage U _β.

According to different application scenarios, autotransformer can carry out suitable selection.Select common autotransformer under general application scenario, common autotransformer one secondary side has a common port, and a secondary side has common winding part.For being applicable to the feature of AT power supply system of electrified railway, the present invention includes a kind of step-up auto-transformer, its concrete feature and the mode of connection are summarized as follows:

Autotransformer first side winding is de, and secondary side winding is fh.De umber of turn is fh umber of turn is 2W ₀.Wherein fe is a secondary side common winding, and the number of turn is W ₀.Autotransformer e holds the mid point for fh winding, holds be connected with the o of T wiring three phase transformation two-phase transformer, and autotransformer d end is held with T wiring three phase transformation two-phase transformer c and is connected.

T wiring three phase transformation two-phase transformer output voltage U _abas U _β, autotransformer output voltage U _fhas U _α.T wiring balancing transformer output voltage U _α, U _βthe traction power supply net both sides be respectively in electric railway AT supply power mode power, and T wiring three phase transformation two-phase transformer o end is held with autotransformer e and can be connected rail and ground network.

T wiring three phase transformation two-phase Circuit Fault on Secondary Transformer winding need meet simple impedance relationship, and impedance relationship is shown below:

$\left\{\begin{array}{c}{Z}_{\mathrm{ao}}+Z_{\mathrm{ob}}=Z_{\mathrm{bc}}=Z_{\mathrm{ca}}\\ Z_{\mathrm{ao}}=Z_{\mathrm{ob}}\end{array}\right.---\left(2\right)$

Beneficial effect:

T wiring balancing transformer primary side neutral point of the present invention can ground connection, and secondary side is connected into triangle and is conducive to triple-frequency harmonics circulation, and has simple for structure, and wiring is simple, capacity utilization and copper product utilance advantages of higher.T wiring three phase transformation two-phase Transformer Winding is few, and three-phase windings total number of turns is equal, and do not need to carry out special arrangement to winding, Design and manufacture difficulty is low.The present invention is especially suitable for use as the traction substation main transformer in electric railway AT supply power mode.

Accompanying drawing explanation

Fig. 1 is T wiring balancing transformer winding connection schematic diagram

Fig. 2 is T wiring three phase transformation two-phase transformer voltage phasor diagram

Fig. 3 is that T wiring three phase transformation two-phase transformer adopts three-phase pillar core structure to implement schematic diagram

Embodiment

Below with reference to the drawings and specific embodiments, the present invention is described in further details:

Embodiment:

As shown in Figure 1, T wiring balancing transformer is made up of T wiring three phase transformation two-phase transformer and step-up auto-transformer (AT), and T wiring three phase transformation two-phase transformer first side winding is made up of three-phase windings AN, BN and CN, adopts star-star connection; Secondary side winding is by A phase winding ao and ob, and B phase winding bc, C phase winding ca form.Wherein ao and ob is that points of common connection connects into ab winding with o, and ab, bc, ca connect into closed triangle, forms the path of triple harmonic current.Primary side A, B and C form three-phase system, and its neutral point N allows ground connection; Secondary side a, b and c, o form binary system.The number of turn of three phases winding at primary side is W ₁, the number of turn of secondary side winding bc and ca is W ₂, the number of turn of ao and ob is 0.5W ₂.

In Fig. 2, each length of side had both represented the number of turn of winding, also represented the size of winding floating voltage.As seen from Figure 2, ab and co is vertical, and $U_{\mathrm{co}}=(\sqrt{3}/2)U_{\mathrm{ab}}.$

As shown in Figure 1, secondary side c, o voltage output end connects a step-up auto-transformer.Autotransformer first side winding is de, and secondary side winding is fh.De umber of turn is fh umber of turn is 2W ₀.Wherein fe is a secondary side common winding, and the number of turn is W ₀.Autotransformer e holds the mid point for fh winding, holds be connected with the o of T wiring three phase transformation two-phase transformer; Autotransformer d end is held with T wiring three phase transformation two-phase transformer c and is connected.Autotransformer secondary side f, h export and U _absize is identical, the voltage U of phase 90 ° _fh.T wiring balancing transformer exports two-phase voltage U _α=U _ab, U _β=U _fh.

Fig. 3 is the embodiment that T wiring three phase transformation two-phase transformer adopts three-phase pillar core structure.In the present embodiment, adopt three-phase pillar iron core, two windings of B phase and C phase are arranged on the stem stem on iron core both sides, and 3 windings of A phase are arranged on middle stem stem; First side winding AN, BN, CN are outside stem stem.Secondary side winding ao, ob near stem stem, and arrange up and down about winding AN, and winding bc and ca is near stem stem.

For the three-phase pole structure transformer shown in Fig. 3, for meeting the impedance relationship shown in formula (2), can opposing connection packet size and mutual alignment suitably adjust.Concrete implementation step is as follows:

(1) according to insulating requirements determination secondary side winding ao, distance between ob, bc and ca and stem stem.

(2) adjust the radial direction between winding or axial distance (coil axial height or radial thickness can be changed if desired), make the equivalent impedance of each winding meet formula (2).The feature invariant of Fig. 3 is kept during adjustment.

Claims (3)

1. a T wiring balancing transformer, comprise a T wiring three phase transformation two-phase transformer and a step-up auto-transformer, wherein T wiring three phase transformation two-phase transformer comprises iron core, first side winding and secondary side winding, it is characterized in that T wiring three phase transformation two-phase transformer first side winding adopts the wiring of Y type, its neutral point allows ground connection, and the first side winding number of turn is W ₁;

In secondary side winding, A phase winding is made up of ao and ob two windings, and B phase winding is bc winding, and C phase winding is ca winding;

The number of turn of bc and ca winding is W ₂, the number of turn of ao and ob winding is 0.5W ₂;

Ao and ob winding with o point for common point connects into ab winding, ab, bc and ca winding respectively with a, b, c for points of common connection is connected into triangle;

Secondary side ab output output voltage U _ab, co output output voltage U _co, and phase 90 °;

Secondary side co output connects a step-up auto-transformer, and step-up auto-transformer no-load voltage ratio is first side winding is de, and to be fh, de umber of turn be secondary side winding fh umber of turn is 2W ₀, fe is a secondary side common winding, and the number of turn is W ₀, autotransformer primary side e holds the mid point for fh winding, and e end is held with the o of T wiring three phase transformation two-phase transformer and is connected, and d end is held with T wiring three phase transformation two-phase transformer c and is connected.

2. T wiring balancing transformer according to claim 1, is characterized in that, described T wiring three phase transformation two-phase transformer core is three-phase pillar iron core or three-phase shell type core.

3. T wiring balancing transformer according to claim 1, is characterized in that, described T wiring three phase transformation two-phase transformer o end is held with step-up auto-transformer e and can be connected rail and ground network.