CN1031433C - Balanced impedance matching transformer - Google Patents

Abstract

The present invention relates to an impedance matching balanced transformer which comprises an iron core, three groups of windings A, B and C, etc. The present invention is characterized in that the arrangement of phase windings of A and C are the same and both have three windings; the winding ax (or cz) is divided into two windings which are connected in series, and the middle-phase winding has four windings; electromagnetic capacities of three phases of A, B and C are the same, and the number of ampere-turns are respectively balanced. The equivalent impedance of all windings of the three phases of A, B and C has the relation that ZAx=Zby=Zcz=Zax=Zcz=1*Zby/(3<1/2>+1). When short circuits occur at three points of c, d and e, the impedance of three phase short circuits is equal by looking from a former direction. The present invention is suitable for transforming symmetrical three phase voltage to voltage which has two phase equal amplitude values and has phase difference as 90 DEG, or is suitable for the condition of the inverse transformation of the transformation.

Description

Balanced impedance matching transformer

The invention belongs to a kind of novel balancing transformer, be specifically related to that symmetrical three-phase electrical power system is transformed to the two-phase amplitude and equate that phase difference is the two-phase electric power system of 90 ° of electrical degrees each other; Or amplitude equated phase difference is the balanced impedance matching transformer that the two-phase electric power system of 90 ° of electrical degrees is transformed to symmetrical three-phase electrical power system each other.

The balancing transformer that China is used for traction substation of electric railway at present mainly is Scott (Scott) wiring (claiming the wiring of a T shape again) transformer, three-phase side is the inverted T-shaped wiring, the two-phase side is L shaped wiring, it can be made of two single-phase transformers, or two single-phase transformer coils is around on two stem stems of tri-phase iron core.When the Scott wiring transformer equates when two-phase side size of current, three-phase side electric current symmetry.That is, not only non-negative sequence current but also non-zero-sequence current.When the two-phase side has equal and opposite in direction, during power supply that the phase phasic difference is 90 °, what three-phase side obtained is balanced three-phase voltage.But the Scott wiring transformer is under low-pressure side load variations situation, the neutral point current potential is drift significantly, directly ground connection has zero-sequence current, cause interference to communication, and make former side's three-phase voltage asymmetric, jeopardize the security of operation of transformer, so the direct ground connection of former side's neutral point can only be applied to 110KV and following electric power system.Like this, the insulation of former side's high pressure winding must consider by line voltage, and manufacturing cost is increased, and the Scott wiring transformer is because of no delta connection winding, increased the content of the triple-frequency harmonics in magnetic flux and the electromotive force, to the adverse effect of electric power system, and all bigger to the interference of communication along the line.In addition, Scott wiring transformer winding complicated layout, tap changer is also relatively more difficult.

The objective of the invention is, utilize impedance matching methods, directly ground connection of a kind of former side's neutral point is provided, be mainly used in 110KV and more than, can be applicable to simultaneously the electric power system that 110KV is following again, the balancing transformer that the three-phase side tap changer easily, triple-frequency harmonics content is less, cost is low, applicability is wide.

Balanced impedance matching transformer of the present invention, comprise A unshakable in one's determination, B, C three phase windings, fuel tank and radiator etc., be characterized in that three-phase side AX, BY, CZ are star or delta connection, the two-phase side adds two support arm winding da and be mutually at middle phase B on the basis of delta connection.Identical three windings that are of the layout of A, C phase winding, winding ax (or cz) is divided into two windings in series, and middle phase B is four windings mutually.A, B, C three-phase electromagnetic capacity equate each self-balancing of number of ampere turns.The number of turn of each winding is closed:

W _AX＝W _BY＝W _CZ＝W _I

W _ax＝W _by＝W _cz＝W _II $W_{\mathrm{da}}=W_{\mathrm{be}}=\frac{1}{2}(\sqrt{3}-1)W_n.$

W _c2＝W _a2

W _c3＝W _a3

The equivalent impedance of A, B, each winding of C three-phase closes:

Z _AX＝Z _BY＝Z _CZ $Z_{\mathrm{ax}}=Z_{\mathrm{cz}}=\frac{1}{\sqrt{3}+1}{Z}_{\mathrm{by}}$ $Z_{\mathrm{ax}}={\left(\frac{W_{a2}}{W_I}\right)}^2{Z^{\&prime;}}_{a2}+{\left(\frac{W_{a3}}{W_I}\right)}^2{Z^{\&prime;}}_{a3}$ $Z_{\mathrm{by}}=\frac{1}{2}(Z_{\mathrm{KB}14}+Z_{\mathrm{KB}24}^{\&prime;}-Z_{\mathrm{KB}12}).{\left(\frac{W_{\mathrm{II}}}{W_I}\right)}^2$ $Z_{\mathrm{cz}}={\left(\frac{W_{c2}}{W_I}\right)}^2{Z^{\&prime;}}_{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="C9210715200081.png"\; state="\{\{state\}\}">c</figure-callout>}2}+{\left(\frac{W_{c3}}{W_I}\right)}^2{Z^{\&prime;}}_{c3}$

Two support arm windings should be strengthened electromagnetic coupled, accomplish that both equivalent leakage impedances equate, so that when c, d, 3 short circuits of e, by the condition that the three-phase shortcircuit impedance of seeing into from former side should equate, determine the support arm impedance.

Satisfy the balanced impedance matching transformer of above-mentioned number of turn relation and impedance matching relation, when the size of two-phase lateral load and power factor were identical, three-phase side was a symmetrical system, both non-negative sequence current, non-zero-sequence current again.If the two-phase side joint is that amplitude equates that phase difference is 90 ° a power supply, three-phase side obtains the three-phase voltage of symmetry.The present invention is further described as follows below in conjunction with accompanying drawing:

Fig. 1 is winding connection figure of the present invention.AX, BY, CZ are respectively the winding of A, B, C three-phase side.N is a neutral point, and ax is the winding in the A phase triangle, and cz is the winding in the C phase triangle, and by is the winding in the B phase triangle, and da is two support arm windings of the middle phase of B mutually be.

Fig. 2 is the winding layout of balanced impedance matching transformer and the schematic diagram of connected mode embodiment.AX, BY, CZ are the winding of A, B, C three-phase side.N is a neutral point, can be according to system's needs ground connection or earth-free.Ax, by, cz are A, B, the winding of C three-phase in the triangle of two-phase side, and wherein ax, cz are divided into two winding serial connections respectively, and B each support arm winding da mutually is connected in series arranged crosswise with the winding that bc is divided into two equal turn numbers.According to Fig. 1, a links to each other with y in the two-phase side, and x links to each other with c, and b links to each other with z.

As shown in Figure 2, the iron core of transformer is a uiform section three pillar type iron core, A, C phase winding are arranged identical, be general two winding transformer, winding ax (or cz) splits into two windings in series, presses three-winding transformer and arranges that winding AX (or CZ) is arranged in outermost layer (or innermost layer, decide on buck or boost), the number of turn of establishing A (or C phase) the 2nd winding is W _A2(or W _C2); The number of turn of the 3rd winding is W _A3(or W _C3).B is four general winding transformers mutually, same A, C are the same mutually, winding BY can be arranged in outermost layer or innermost layer, winding by is arranged in innermost layer or outermost layer, two support arm winding da, bc are divided into two windings intersection serial connections respectively and are arranged in middle, can reduce the equivalent impedance of support arm winding da, be like this, and guarantee the symmetry of electromagnetic performance by the symmetry of arranging.

The present invention is applicable to that mainly the main transformer of traction substation of electric railway or other need be transformed to the three-phase voltage of symmetry the two-phase amplitude and equate that phase difference is 90 ° a voltage, or carries out the situation of the inverse transformation of above-mentioned conversion.This transformer is applicable to the direct-furnish or the BT supply power mode of railway electric power system.The three-phase side of transformer is connected to three-phase electrical power system, neutral point N can according to electric power system require ground connection or earth-free, the two-phase side is the power supply of the net of row traction up and down respectively.If two-phase side joint amplitude equates that phase difference is 90 ° a power supply, the symmetrical voltage that obtains from three-phase side can be used for electric substation from electricity consumption or regional load power supply etc.Because this transformer can be drawn neutral ground, has reduced the class of insulation, the insulation manufacturing cost is reduced.In addition, this transformer material utilance is higher, and tap changer also is easier to.Because the delta connection winding is arranged, be convenient to by excitatory triple harmonic current, can reduce the triple-frequency harmonics content of magnetic flux and electromotive force, thereby reduce the adverse effect of electric power system with communication along the line.

Claims (1)

1, a kind of balanced impedance matching transformer, comprise iron core, A, B, C three phase windings, fuel tank and radiator etc., it is characterized in that three-phase side AX, BY, CZ are star or delta connection, the two-phase side is on the basis of delta connection, add two support arm winding da and be mutually at middle phase B, identical three windings that are of the layout of A, C phase winding, winding ax (or cz) is divided into two windings in series, middle phase B is four windings mutually, A, B, C three-phase electromagnetic capacity equate, each self-balancing of number of ampere turns, the number of turn of each winding are closed and be:

W _AX＝W _BY＝W _CZ＝W _I

W _ax＝W _by＝W _cz＝W _II $W_{\mathrm{da}}=W_{\mathrm{be}}=\frac{1}{2}(\sqrt{3}-1)W_{\mathrm{II}}.$

W _c2＝W _a2

W _c3＝W _a3

The equivalent impedance of A, B, each winding of C three-phase closes:

Z _AX＝Z _BY＝Z _CZ $Z_{\mathrm{ax}}=Z_{\mathrm{cz}}=\frac{1}{\sqrt{3}+1}-Z_{\mathrm{by}}$ $Z_{\mathrm{ax}}={\left(\frac{W_{a2}}{W_I}\right)}^2{Z^{\&prime;}}_{a2}+{\left(\frac{W_{a3}}{W_I}\right)}^2{Z^{\&prime;}}_{a3}$ $Z_{\mathrm{by}}=\frac{1}{2}(Z_{\mathrm{KB}14}+{Z^{\&prime;}}_{\mathrm{KB}24}-Z_{\mathrm{KB}12})\&CenterDot;{\left(\frac{W_{\mathrm{II}}}{W_I}\right)}^2$ $Z_{\mathrm{cz}}={\left(\frac{W_{c2}}{W_I}\right)}^2{Z^{\&prime;}}_{c2}+{\left(\frac{W_{c3}}{W_I}\right)}^2{Z^{\&prime;}}_{c3}$

The equivalent leakage impedance of two support arm windings equates, so that when c, d, 3 short circuits of e, by the condition that the three-phase shortcircuit impedance of seeing into from former side equates, determines the support arm impedance.

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