RU2418332C1 - Electric three-phase inductor with magnetic bias - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: electric three-phase inductor includes magnetic system which is made of laminated electrotechnical steel plates, magnetic conductor with coaxially located three upper and three lower vertical rods. Two-section coils are arranged on rods. In magnetic conductor there are upper, lower and middle horizontal yokes and two side vertical yokes; at that, horizontal yokes have two middle and two end sections, four magnetic shunts in the form of rectangular frames with horizontal and vertical sections; at that, horizontal sections of shunts are located on edges of coils along upper, middle and lower yokes. Vertical sections closing them are located along side yokes. Inductor also includes controlled semiconductor converters from diodes and resistors, and control system. Inductor coils are connected to three-phase network and to converters; to inductor there introduced are three-coil insulating transformers installed between converters and control system; non-magnetic gaps are made in sections of middle horizontal yoke of magnetic conductor. Each magnetic shunt has two additional vertical sections located between coils. Ratio of values of non-magnetic gaps of magnetic conductor in end sections of middle yoke Δ_end and values of nonmagnetic gaps in middle sections of middle yoke Δ_middle is 1.5<(Δ_middle/Δ_end)<3; ratio between steel section of middle sections of middle yokes S_{middle yoke} and section of rods S is within 0.9<(S_{middle yoke}/S)<1.3; ratio between steel section of all the other sections of yokes S_yoke and section of rods S is within 0.7<(S_yoke/S)<0.9; ratio between steel section of all parts of magnetic shunts S_shunt and section of rods S is within 0.07<(S_shunt/S)<0.3.

EFFECT: reduction of steel consumption and losses, improvement of reliability, enlargement of functional capabilities and power control range.

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Description

The invention relates to the field of electrical engineering and can be used for magnetically controlled reactors installed, for example, in an electrical network to compensate for reactive power, stabilize voltage, parallel operation with capacitor banks, increase throughput, etc.

Known electric three-phase reactor with magnetization [1], containing a charged magnetic system with upper, lower, middle and two side yokes, coaxial upper and lower rods located on the rods of the upper and lower windings, as well as inputs, semiconductor diodes and thyristors. The disadvantage of this device, an analogue, is the increased consumption of steel of the magnetic circuit due to the increased magnetic flux in it (from the scattering magnetic field) in the load conditions of the reactor, and also because of the non-optimal choice of the parameters of the magnetic circuit.

This drawback was partially eliminated in [2]. An electric three-phase magnetization reactor contains a charged magnetic system with three upper and three lower coaxial rods, with upper, lower, middle and two side yokes, the horizontal yokes having two middle and two extreme sections. The windings located on each core consist of two parts. The inputs of the reactor are connected to parts of the windings and converters with a control system. Four magnetic shunts are installed in the reactor in the form of rectangular frames with horizontal and vertical parts, and the horizontal parts of the shunts are located at the ends of the windings along the upper, middle and lower yoke, and the vertical parts closing them are located along the side yards. The disadvantage of this device, the prototype, is also the increased consumption of steel of the magnetic circuit due to the increased magnetic flux in it (from the magnetic field of the scattering) in the load conditions of the reactor due to the suboptimal design and parameters of the shunts and magnetic circuit. In addition, the range of regulation of reactor power is limited and reliability is reduced due to the danger of high voltage occurrence in emergency cases on the control system due to its galvanic connection with the reactor windings.

The aim of the invention is to reduce the consumption of steel and losses, increase reliability, increase the functionality of the reactor - expanding the range of power control - by introducing new elements into the design and electrical circuit, new connections between elements, optimizing the ratio of parameters.

This goal is achieved by the fact that in an electric three-phase reactor with magnetization, the magnetic system of which is made of charged sheets of electrical steel and contains a magnetic circuit with coaxially located three upper and three lower vertical rods, on which two-section windings are located, upper, lower and middle horizontal and two lateral vertical yokes, and the horizontal yokes have two middle and two extreme sections, four magnetic shunts in the form of rectangular frames with horizontal and vertical sections, and the horizontal sections of the shunts are located on the ends of the windings along the upper, middle and lower yoke, and the vertical sections closing them are located along the side holes, and the reactor also contains controllable semiconductor converters of diodes and resistors and a control system, said windings being connected to three-phase network and with converters, three-winding isolation transformers installed between the converters and the control system are introduced into the reactor. Nonmagnetic gaps are made in the sections of the average horizontal yoke of the magnetic circuit. Each magnetic shunt has two additional vertical sections located between the windings. The ratio of the values of the non-magnetic gaps of the magnetic circuit in the extreme sections of the average yoke Δ _extreme. and values of non-magnetic gaps in the middle sections of the average yoke Δ _average. (Δ _average / Δ _extreme ) is

1.5 <(Δ _average / Δ _extreme ) <3.

The relationship between the steel section of the middle sections of the middle jug S _avg. and the cross section of the rods S is within

0.9 <(S _avg / S) <1.3,

the ratio between the steel section of all other sections of the yoke S _yar. and the cross section of the rods S is within

0.7 <(S _bright / S) <0.9,

the ratio between the steel cross section of all parts of the magnetic shunts S _W and the cross section of the rods S is within

0.07 <(S _w / S) <0.3.

The proposed reactor with magnetization is illustrated by drawings. Figure 1 shows the withdrawal part of the reactor (magnetic system with windings) - front view, figure 2 is the same, top view, figure 3 is the same side view. Figure 4 shows the main magnetic circuit laden from sheets of electrical steel, figure 5 shows one of the four magnetic shunts laced from sheets of electrical steel in the form of a rectangular three-window frame. Figure 6 shows the electrical circuit of the reactor.

The magnetic system of the reactor, laden from sheets of electrical steel, consists of a main magnetic circuit and four magnetic shunts.

The magnetic core of the reactor (Figs. 1-4) contains six coaxial rods - three upper 1, 2, 3 and three lower 4, 5, 6. On each rod there is a winding consisting of two sections 7 and 8. There are two lateral vertical yokes 9 and 10, as well as three horizontal yokes - the upper yoke 11, the lower yoke 12, and the average yoke 13. The section of the steel of the rods is S, the section of the steel of all the yards except the average yoke is S _i , the section of the steel of the middle yoke is S _cf. .

Each of the horizontal yards 11, 12 and 13 has four sections: two extreme and two middle.

All sections of the average horizontal yoke 13 have non-magnetic gaps 14 (the size of the gap in the middle sections Δ _average. ) And 15 (the size of the gap in the extreme sections Δ _extreme. ).

Each of the four magnetic shunts 16 is made in the form of a rectangular three-window frame (figure 5). The horizontal parts of the shunts are located at the ends of the windings (between the end of the winding 7 and 8 and the pressing beam 17, Fig.3). Shunts 16 have two middle vertical parts 18 located between the windings. All parts of the magnetic shunts have a steel section S _w,.

The electrical circuit of the reactor (Fig.6) contains three input phase network A, B and C.

Two sections 7 and 8 of the winding on the upper rod 1 of phase A have taps A1-A2 and A3-A4, on the lower coaxial rod 4 there are taps A5-A6 and A7-A8. Two sections of the winding on the upper rod 2 of phase B have taps B1-B2 and B3-B4, on the lower coaxial rod 5 - B5-B6 and B7-B8. Two sections of the winding on the upper rod 3 of phase C have taps C1-C2 and C3-C4, on the lower coaxial rod 6 - C5-C6 and C7-C8.

The windings are connected to the circuit of two triangles and connected to the three inputs of the phases of the network A, B and C.

Between each two sections of the windings of each rod there is a converter consisting of a parallel connected diode D and resistor R: between the taps A2 and A3, the converter P _{1A is} connected, between the taps A6 and A7 - the converter P _2A , between the taps B2 and B3 - the converter P _1B , between taps B6 and B7 - converter П _2B , between taps C2 and C3 - converter П _1C between taps C6 and C7 - converter П _2C . The terminals of the transducers are marked in the same way as the taps of the parts of the windings with which they are connected. In all six converters, the diodes D and the resistors R are the same.

Between the control system (SU) and the converters, three-winding isolation transformers T _A , T _B and T _{C are} installed. Each primary sectioned winding of the transformer is connected by its terminals (U _1A- U _2A , U _1B- U _2B and U _1C- U _2C ) to the control system. Each of the two secondary windings is connected to the taps of the sections of the control windings and the terminals of the converters. The transformer T _{A has} one secondary winding connected to the taps A2 and A6 and simultaneously to the terminals of the transducer A2 and A6, the second to the taps A3 and A7 and simultaneously to the terminals of the transducer A3 and A7. For transformer T _B, one secondary winding is connected to taps B2 and B6 and terminals B2 and B6, the second to taps B3 and B7 and terminals B3 and B7. For transformer T _C, one secondary winding is connected to taps C2 and C6 and terminals C2 and C6, the second to taps C3 and C7 and terminals C3 and C7.

Converters and isolation transformers are placed on the assembly panel 19, mounted on the withdrawal part (figure 2). The extraction part — the reactor’s magnetic system (magnetic circuit and shunts) with windings and press-fit structural elements — is placed in the oil tank.

Consider the operation of the reactor.

The reactor is connected to a three-phase network by inputs A, B and C, the mains voltage is supplied to the reactor windings.

To transfer the reactor to the minimum power mode - idle mode - the control system of the control system provides at the terminals U _1A- U _2A , _1B- U _2B and U _1C- U _2C minimum resistance. Since the isolation transformers T _A , T _B and T _C are in this case in short circuit mode, and their scattering resistance is small, the taps of the winding sections A2 and A3, A6 and A7, B2 and B3, B6 and B7, C2 and C3, C6 and C7 turn out to be almost pairwise shorted. Moreover, each of the transducers P _1A and P _2A , P _1B and P _2B , P _1C and P _{2C is} practically short-circuited, and there is no magnetization of the magnetic core rods.

In the case when the control system of the control system connects the maximum resistance to the taps U _1A- U _2A , U _1B- U _2B and U _1C- U _2C , the reactor switches to the maximum power mode - full-time saturation of the rods. This is due to the fact that the diodes D of the converters P _1A , P _2A , P _1B , P _{2B are} connected to the taps of the sections of the windings A2 and A3, A6 and A7, B2 and B3, B6 and B7, C2 and C3, C6 and C7 , P _1C and P _2C .

Intermediate modes from idle to maximum power are provided by the control system of the control system according to a given program (for example, to stabilize the mains voltage) or with manual adjustment. In this case, the rated power mode, as a rule, is set for one of the intermediate modes - the half-period saturation reactor mode. In this mode, the steel of each core of the reactor is in a saturated state for half a period. Such a regime is characterized not only by minimal (theoretically zero) distortions of the reactor current by higher harmonics, but also by the optimal consumption of active materials and optimal losses in the windings.

Isolation transformers are installed between the control system (it is located on the control panel in the room) and the converters, ensuring the absence of galvanic communication and increased safety of personnel and low-voltage equipment from possible high-voltage supply to the control system (for example, in emergency situations). The converters, together with isolation transformers, are located on panel 19 in the reactor tank located in the open area of the substation.

Non-magnetic gaps 14 and 15 are made in the sections of the average horizontal yoke 13 of the magnetic circuit. These gaps are necessary in order to expand the limits of regulation of the reactor power. The magnitude of non-magnetic gaps should be minimal; when designing a reactor, it is selected from the technological capabilities of production and is usually fractions or units of millimeters.

In the magnetic circuit, the magnitude of the nonmagnetic gap in the extreme sections of the average yoke Δ _extreme should be less than the magnitude of the nonmagnetic gap in the middle sections of this yoke Δ _average (1.5 ÷ 3) times, i.e.

1.5 <(Δ _average / (Δ _extreme ) <3.

The upper boundary should not be exceeded, otherwise the magnetic flux of scattering in the extreme vertical parts of the shunt will be reduced, and in the middle it will be increased. The lower boundary must also be observed, otherwise the magnetic flux of scattering will be increased in the vertical extreme parts of the shunt, in the middle vertical parts of the shunt will be reduced. Fulfillment of the optimal gap size ratio allows one to obtain a favorable distribution of magnetic induction over the rods, yokes and shunts, as well as minimum steel consumption with maximum shunt efficiency in terms of unloading the main magnetic core of the reactor and reducing additional losses in the structural elements and tank wall.

The choice of the cross-sectional area of steel of all sections of the magnetic circuit is important.

The ratio between the steel cross section of the sections of the average yoke S _{cf. yar} and the cross section of the rods S should be chosen within

0.9 <(S _avg / S) <1.3.

The ratio between the steel cross section of all other sections of the yoke S _yar and the cross section of the rods S - should be selected within

0.7 <(S _yar / S) <0.9.

If the cross section of steel with a yoke exceeds the maximum boundary, then the reactor is obtained with an increased consumption of steel in yokes. If the steel cross section of the yoke is less than the minimum value, then steel saturation occurs in the reactor yokes in certain modes of its operation. This leads to unfavorable phenomena - an increase in additional losses due to eddy currents in structural elements, and an increase in nonlinear distortions in the reactor current.

Magnetic shunts 16 effectively “channelize” the magnetic flux of scattering that occurs when current flows in the windings, i.e. in all modes when magnetizing rods. The magnetic flux of scattering circulates in the axial direction inside the windings and closes by the yokes of the magnetic system and by magnetic shunts. If there are no magnetic shunts 16, then the magnetic flux closes along the structural elements and the tank wall, causing eddy currents, additional losses and unacceptable heating in them. For effective magnetic flux closure, shunts have middle longitudinal vertical sections 18 located between the windings. These two additional (compared with the prototype) vertical sections are necessary for the optimal distribution of magnetic fluxes of scattering and reduce the total consumption of steel in shunts and magnetic circuit.

The steel cross section of magnetic shunts should be the larger, the larger the radial size of the windings, because when the reactor is loaded, an increased magnetic flux of scattering occurs (compared with the magnetic flux in the rods and yokes of the magnetic circuit in idle mode).

The ratio between the steel cross section of all parts of each of the magnetic shunts S _W , and the cross section of the rods S should be selected within

0.07 <(S _w / S) <0.3.

If the steel cross section of the magnetic shunts is chosen to be larger than the maximum value of the specified ratio, then an overspending of steel is obtained. If the steel cross section of the shunts is less than the minimum value, then the shunts become ineffective and do not shield the scattering flux of the windings. This leads to adverse phenomena - an increase in magnetic induction in the magnetic circuit, the main losses in steel and additional losses in structural elements.

The proposed improved “three-window” shunt design compared to the prototype ensures an optimal distribution of the magnetic fluxes of the reactor, and, consequently, an optimal consumption of steel in the magnetic system.

All the considered limits of optimal size ratios were determined as a result of the analysis of numerous calculations on mathematical models controlled by magnetizing reactors in a wide range of variation of their parameters. If necessary, the examination can be provided with the detailed results of these calculations.

A high voltage reactor is typically oil cooled. The extraction part — the reactor’s magnetic system (magnetic circuit and shunts) with windings and press-fit structural elements — is placed in the oil tank, and the reactor inlets are on the tank cover. Converters and isolation transformers are located in the same tank on an assembly panel mounted on a removable part.

The performance of the proposed reactor and its high technical and economic indicators are confirmed by calculations, physical modeling, test results of prototypes of similar designs. In the proposed reactor, in comparison with analogues and prototype, steel consumption is reduced, losses are reduced, reliability is increased, as well as labor costs in manufacturing, dimensions and weight are reduced. In the near future it is planned to manufacture prototypes for mass production.

LITERATURE

1. Bryantsev A.M. "Electric reactor with magnetization." Patent RU No. 23234251, application: 2006146290/09, 12.26.2006. Published: May 10, 2008.

2. Bryantsev A.M. "Electric reactor with magnetization." RU patent No. 2324250, application: 200614529909, 12.20.2006. Published: May 10, 2008.

Claims (1)

An electric three-phase magnetization reactor, the magnetic system of which is made of charged sheets of electrical steel and contains a magnetic circuit with coaxially located three upper and three lower vertical rods, on which two-section windings, upper, lower and middle horizontal and two side vertical yokes are placed, with horizontal yokes have two middle and two extreme sections, four magnetic shunts in the form of rectangular frames with horizontal and vertical sections, and the horizontal The total sections of the shunts are located at the ends of the windings along the upper, middle, and lower yokes, and the vertical sections closing them are located along the lateral yards, and the reactor also contains controllable semiconductor converters of diodes and resistors and a control system, the windings being connected to a three-phase network and to converters characterized in that three-winding isolation transformers installed between the converters and the control system are introduced into the reactor in middle horizontal sections the yoke of the magnetic circuit non-magnetic gaps are made, each magnetic shunt has two additional vertical sections located between the windings, the ratio of the non-magnetic gaps of the magnetic circuit in the extreme sections of the average yoke Δ _extreme. and values of non-magnetic gaps in the middle sections of the average yoke Δ _average. makes up
1.5 <(Δ _average / Δ _extreme ) <3,
the ratio between the steel section of the middle sections of the middle jug S _sr. and the cross section of the rods S is within
0.9 <(S _avg / S) <1.3,
the ratio between the steel section of all other sections of the yoke S _yar. and the cross section of the rods S is within
0.7 <(S _bright / S) <0.9,
the ratio between the steel cross section of all parts of the magnetic shunts S _W and the cross section of the rods S is within
0.07 <(S _w / S) <0.3.

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