RU2255411C1 - Transformer converter - Google Patents

Abstract

FIELD: electrical and power engineering systems, plants, and pieces of equipment.

SUBSTANCE: two-phase winding of transformer converter has several series-connected groups whose number equals number of regulation stages; each group, in its turn, has six coils whose turn number is correlated by expression

where K may vary within

Three first and three remaining coils in each group form two half-groups that function as phase members of two-phase winding.

EFFECT: enlarged functional capabilities.

2 cl, 1 dwg

Description

The invention relates to electrical engineering and, in particular, to transformer construction and is intended for reversible mutual conversion of electrical energy of three- and two-phase voltages and currents.

The purpose of the invention is the expansion of functionality and design options.

Known transformer converters of electrical energy of three-phase sinusoidal voltages and currents into two-phase, containing a spatial three-core magnetic circuit located on it with a three-phase input and two-phase output windings [1], [2].

The disadvantages of such converters are the inability to control the output voltage, as well as a strictly fixed ratio of the number of turns of sections of the two-phase winding: in [1] it is cos15 °: cos45 °: cos75 °, and in [2] -

The transformer converter of electric energy of three-phase voltages and currents into two-phase, proposed as an invention, provides a complete conjugation of the parameters of the symmetrical modes of the three-phase and two-phase networks, in which all symmetry requirements are satisfied regardless of the power of the network and consumers. In this case, a significant variation in the number of turns of sections of a two-phase winding, as well as voltage regulation by switching its sections, is possible.

This is achieved due to the fact that in a transformer converter consisting of at least three cores (for example, A, B, C) of the same cross section of a rod or group type, a three-phase winding consisting of at least three identical with the number turns of W _t phases (for example, A, B, C) located on the corresponding cores of the magnetic circuit, interconnected in a star or delta and connected to a three-phase network, and a two-phase winding connected to a two-phase network, a two-phase winding is made consisting of several series-connected groups (for example, 1,2,3, n ... N), the number of which is equal to the number N of regulation steps, each group, in turn, consists of, in general, six sections: two (for example , W _ad and W _aq ) located on core A, two (for example, W _bd and W _bq ) located on core B, and two (for example, W _ed and W _cq ) located on core C, sections W _ad and W _{bd are} connected in series according to each other and in series with the section W _ed and form a semigroup of the first phase D of the two-phase winding, sections W _bq and W _{cq are} connected by consequently according to each other and successively counter to the section W _aq and form a semigroup of the second phase Q of the two-phase winding, while in any group of six sections (for example, the “n” th), the number of turns of sections should be related to each other as

moreover, the ratio K = W _cq / W _aq can vary arbitrarily within

A transformer converter can be made, this is one of its significant advantages, on the basis of a standard three-phase transformer of any type produced by the electrical industry (group, rod, armored, armored, etc.). The three-phase winding is also standard and consists of three phases identical with the number of turns W _m , which are located on three different cores of the magnetic circuit and can be connected into a star or a triangle.

The electrical circuit of the transformer converter (for example, based on a three-core magnetic circuit) is shown in figure 1. As follows from the circuit of Fig. 1, a two-phase winding consists, in the general case, of 6N sections, which makes it possible to simultaneously satisfy all the requirements of the symmetrical modes of the three-phase and two-phase power supply systems and to provide the possibility of symmetric regulation of the output two-phase voltage.

Necessary and sufficient conditions for the symmetrical modes of operation of three-phase and two-phase systems are:

for a three-phase system:

- equality of voltages (U _A , U _B , U _C ), currents [I _A , I _B , I _C ) and magnetizing forces (F _A , F _B , F _c ) of the windings of all phases in magnitude;

- a temporary phase shift between any pair of vectors of voltages, currents and magnetizing forces by 1/3 of a period (120 °);

for a two-phase system:

- equality of voltages (U _D , U _Q ), currents (I _D , I _Q ) and magnetizing forces (F _D , F _Q ) of the windings of all phases in magnitude;

- a temporary phase shift between any pair of vectors of voltages, currents and magnetizing forces by 1/4 of a period (90 °);

together for both systems, based on a common magnetic circuit:

- the sum of the magnetizing forces of the sections located on each individual core of the magnetic circuit must be the same and equal to the magnetizing idling force of any of the phases.

The first two groups of conditions reflect the fact that all electrical quantities (voltages, currents and magnetizing forces) in both a three-phase and a two-phase system consist only of symmetrical components of a direct sequence of phase rotation. The third group of conditions corresponds to the absence of three-phase and two-phase systems of their zero components in currents, magnetizing forces and magnetic fluxes.

The principle of operation of the transformer Converter can be explained as follows.

Under the action of symmetric three-phase voltages U _A , U _B , U _C , symmetric three-phase currents I _A , I _B , I _C arise in the three-phase winding, and a symmetrical system of magnetizing forces F _A = I _A W _m , F _B = I in the cores of the magnetic circuit _B W _m , F _C = I _C W _m and the corresponding magnetic fluxes Ф _А , Ф _в , Ф _с . Magnetic fluxes induce six voltages U _ad , U _bd , U _cd , U _aq , U _bq , U _cq in the sections W _ad , w _bd , W _cd , W _aq , W _bq , W _cq , respectively, in a two-phase winding. Given the connection diagram of the sections (Fig. 1), the phases U _D = U _ad + αU _bd -α ² U _cd and U _Q = -U _aq + αU _bq + α ² U _cq arise in the phases of the two-phase winding. Here α = e ^{-j120 °} and α ² = e ^{j120 °} are the operators of rotation of the stress vectors by - (+) 120 °. In this case, the ratio of the number of turns of sections and the corresponding voltages should provide symmetry conditions in a two-phase system: U _D = jU _Q.

When a symmetrical two-phase receiver is connected to the voltages U _D and U _Q , currents I _D and I _Q arise in the two-phase winding, forming a symmetric system of two-phase currents I _D = jI _Q. Under the action of these currents, magnetizing forces appear in the cores of the magnetic circuit: F _a = I _D W _ad + I _Q W _aq , F _b = I _D W _bd + I _Q W _bq , F _c = -I _D W _cd + I _Q W _cq . In this case, the condition of the symmetric mode of operation of the magnetic circuit of the transformer converter, that is, the absence of magnetizing forces and flows of a zero phase sequence can be represented as: F _a = αР _b = a ² F _c .

As a result, the whole set of conditions for the symmetrical operation of the transformer converter can be reduced to the following system of equations:

Since in the resulting system of equations of six parameters only four are independent, then, taking any of W _ad , W _bd , W _cd , W _aq , W _bq , W _cq as the base one (for example, W _aq = 1 (100%)) , a any other expressing in fractions of the base (for example, W _cq = KW _aq ), we can obtain the ratio for all six parameters

а коэффициент трансформации, представляющий собой отношение фазных напряжений холостого хода двухфазной и трехфазной обмоток, равен

В частности, при К=0,268 и К=0,5 имеют место варианты известных из [1], [2] соотношений параметров: 0,268:0,732:1:1:0,732:0,268 (К_Д/Т-=1,55W_aq/W_T) и 0:0,866:0,866:1:0,5:0,5 (К_Д/Т=1,5W_aq/W_T) (одна группа двухфазной обмотки состоит из пяти секций). Двухфазная обмотка, в общем случае, может состоять из любого количества групп, состоящих, в свою очередь, из двух полугрупп по три секции в каждой. Полугруппы соединены между собой последовательно, как показано на схеме фиг.1. Крайние выводы первых полугрупп двухфазной обмотки соединены с фазами D и Q двухфазной сети, а точки соединения последующих полугрупп между собой, включая крайние выводы последних (например, N-х) полугрупп, через N-позиционный трехполюсный переключатель соединяются с нулевой точкой О двухфазной сети. Таким образом, изменяя положение переключателя и, следовательно, число групп, включенных между выводами фаз D и Q и нулевой точкой О, можно ступенчато регулировать фазные напряжения двухфазной сети. При этом, если числа витков секций во всех группах двухфазной обмотки будут удовлетворять указанному выше соотношению, то напряжения двухфазной сети на всех уровнях будут оставаться симметричными.Moreover, the range of practically feasible values of the parameter K is within

and the transformation coefficient, which is the ratio of the phase no-load voltages of the two-phase and three-phase windings, is equal to

In particular, when K = 0.268 and K = 0.5, there are variants of the known parameter ratios from [1], [2]: 0.268: 0.732: 1: 1: 0.732: 0.268 (K _{D / T} - = 1.55W _aq / W _T ) and 0: 0.866: 0.866: 1: 0.5: 0.5 (K _{D / T} = 1.5W _aq / W _T ) (one group of a two-phase winding consists of five sections). A two-phase winding, in the general case, can consist of any number of groups, which, in turn, consist of two semigroups with three sections in each. Semigroups are interconnected in series, as shown in the diagram of figure 1. The extreme terminals of the first semigroups of the two-phase winding are connected to the phases D and Q of the two-phase network, and the connection points of the subsequent semigroups to each other, including the extreme terminals of the last (for example, N-x) semigroups, are connected to the zero point О of the two-phase network via the N-position three-pole switch. Thus, by changing the position of the switch and, therefore, the number of groups included between the terminals of the phases D and Q and the zero point O, it is possible to stepwise adjust the phase voltages of the two-phase network. Moreover, if the number of turns of sections in all groups of the two-phase winding will satisfy the above ratio, then the voltage of the two-phase network at all levels will remain symmetrical.

Finally, it should be noted that, since the transformer converter is completely analogous to a conventional transformer in terms of its design and principle of operation, it is a reversible converter and can operate in any direction of electric energy between three-phase and two-phase power supply and power consumption systems.

Sources of information

1. USSR author's certificate No. 598197, 10/10/1976, cl. H 02 M 514.

2. French patent No. 2648612, 06/15/1989, cl. H 01 F 33/00.

Claims (2)

1. A transformer converter of three-phase voltage and current into a two-phase, containing a magnetic circuit consisting of at least three cores A, B, C of the same cross section, a three-phase winding consisting of at least three phases identical to the number of turns W _t A, B, C located on the respective cores of the magnetic circuit, interconnected in a star or triangle and connected to a three-phase network, and a two-phase winding connected to a two-phase network, characterized in that the two-phase winding is made consisting of a number of serially connected groups of 1, 2, 3, n ... N, the number of which equals the number N of stages of regulation, each group, in turn, consists of at least six sections: two W _ad, and W _aq, placed on the core A, two W _bd and W _bq placed on the core B, and two W _cd and W _cq placed on the core C, sections W _ad and W _{bd are} connected in series with each other and in series with the section W _cd and form semigroup first phase of two-phase D winding section W _bq and W _cq are connected in series in accordance with each other and n hence with opposite W _aq section and form a subgroup of the second two-phase winding phase Q, wherein in any group of the six sections of sections of coils must relate to each other as a

moreover, K = W _cq / W _aq can vary arbitrarily within

2. The transformer Converter according to claim 1, characterized in that the extreme terminals of the first semigroups of the two-phase winding are connected to the phases D and Q of the two-phase network, and the connection points of the subsequent semigroups to each other, including the extreme terminals of the last semigroups, are connected to the N-position three-pole switch with zero point of a two-phase network.