RU2486619C1 - Electric three-phase inductor with magnetic bias - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: reactor magnetic system is made of laminated electrotechnical steel plates; it contains magnetic conductor with coaxially located three upper and three lower vertical rods. Two-piece windings, upper, lower and medium horizontal and two side vertical yokes are located at rods. Four magnetic shunts are made in the form of rectangular frames with horizontal and vertical sections. The reactor contains linear inputs and current transformers, main and auxiliary semi-conductor converters in the form of chains of paralleled diode and resistor, control system. Windings are connected with three-phase network and converters. Three-winding isolating transformers are installed between converters and control system. Each main and auxiliary chain is connected at one end with one-phase current transformer and at the other end it is connected to two-piece winding of the rod. The medium horizontal yoke of magnet core is made with steel parts having reduced cross-section.

EFFECT: improvement of reliability and reduction of sound level in all modes.

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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 three upper and three lower coaxial rods, with upper, lower, middle and two side yokes. 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. The disadvantage of this analog device is the increased consumption of steel magnetic core due to the increased magnetic flux in it (from the scattering magnetic field) in the reactor load conditions. 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.

These shortcomings were partially eliminated in [2]. An electric three-phase magnetization reactor contains a magnetic system, which is made of laminated 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 lateral vertical yokes are placed. The reactor contains semiconductor converters of diodes and resistors and a control system. The reactor has three-winding isolation transformers. Nonmagnetic gaps are made in the sections of the average horizontal yoke of the magnetic circuit. The disadvantages of this prototype device are the need to shut down the reactor when one diode is damaged and the reactor noise is increased due to the large electrodynamic forces acting on the part of the magnetic circuit in the region of non-magnetic gaps in the average yoke.

The aim of the invention is to increase reliability by optimizing the converter circuit and reducing noise by eliminating non-magnetic gaps.

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 horizontal yokes have two middle and two extreme parts, four magnetic shunts in the form of rectangular frames with horizontal and vertical sections, while the horizontal sections of the shunts are located at the ends of the windings along the upper, middle and lower yoke, the vertical sections closing them are located along the side yards, the reactor also contains linear inputs and current transformers, semiconductor converters in the form of chains of parallel connected diodes and resistors and a control system, said windings being connected to a three-phase network and to converters, three-winding isolation transformers installed between the converter and the control system and the reactor additional converters administered in the form of strings of parallel-connected diodes and resistors and phase current transformers. Each mentioned circuit and the chain of the additional converter is connected at one end to the other through a phase current transformer, and at the other common end it is connected to a two-section winding. The average horizontal yoke of the magnetic circuit is made with sections of a reduced steel section, the ratio of the values of sections of a reduced steel section in the extreme parts of the average yoke Δ _extreme. and middle parts of the average yoke Δ _average. makes up

1.5 <(Δ _average / (Δ _extreme ) <3,

sections of a reduced section of steel are made with alternating solid and cut sheets, and the fill factor with steel of these sections is K _app. is within

0.25≤K app _. ≤0.75.

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 laminated from sheets of electrical steel in the form of a rectangular three-window frame, figure 6 is a fragment of the extreme part of the middle yoke of the lined magnetic circuit of a section of reduced steel section . 7 shows the electrical circuit of the reactor.

The magnetic system of the reactor consists of a main magnetic circuit and four magnetic shunts. The magnetic core of the reactor (Figs. 1-4) contains six coaxial rods - the top three 1, 2, 3 and three bottom 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 - upper 11, lower 12 and middle 13.

Each horizontal yoke 11, 12 and 13 has four parts: two extreme and two middle. All parts of the average horizontal yoke 13 have sections of a reduced section 14 (the size of the reduced section in the middle parts of the average horizontal yoke Δ _average ) and 15 (the size of the reduced section in the extreme parts of the average horizontal yoke Δ _extreme ).

Figure 6 shows that the section of the reduced section of steel in the extreme part of the average horizontal yoke value Δ _extreme. made with alternating solid sheets (plates) of steel 16 and cut and shortened sheets 17. After batching, the cut and shortened sheets 17 form sections free of steel, which are magnetically shunted by solid sheets 16.

The fill factor with steel of these sections To _app. is within

0.25≤K app _. ≤0.75.

The fill factor steel K _app. 6 of the reduced section in FIG. 6 is 0.5, since the alternating layers have an equal thickness. If, for example, the continuous sheets are double, and the cut shortened ones are single, then K _app. = 2/3 = 0.67.

Each of the four magnetic shunts 18 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 19, figure 3). Shunts 18 have two middle vertical parts 20 located between the windings. All parts of magnetic shunts have the same steel section.

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, 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 according to the scheme 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, a converter consisting of two chains is included. Each chain contains a parallel connected diode D and resistor R.

Converter P _{1A is} connected between taps A2 and A3 _, converter P _2A between taps A6 and A7, converter P _1B between taps B2 and B3, converter P _2V between taps B6 and B7, converter P _1C between taps C2 and B3, between taps C6 and C7 - converter P _1C . Each chain is connected at one end to the other through a phase current transformer, and at the other common end it is connected to a two-section winding of the rod.

The findings of the converters are designated in the same way as the taps of the parts of the windings with which they are connected: A1 and A3, A6 and A7, B1 and B3, B6 and B7, C1 and C3, C6 and C7.

Between the control system (SU) and the converters, three-winding isolating transformers T _A , T _B and T _{C are} installed. Each primary sectioned winding of the transformer is connected to the SU with its terminals U _1A- U _2A , U _1V- U _2V and U _1C- U _2C .

Each of the two secondary windings of the transformer is connected to the taps of the winding sections and the leads of the converters. The transformer has one secondary winding connected to the taps A2 and A6 and to the leads of the converter P _{1A of the} same name, the second to the taps of A3 and A7 and the leads of the converter P _{2A of the} same name. Similarly, for a transformer T _B, one secondary winding is connected to the leads B2 and B6 and to the terminals of the converter P _{1V of the} same name, the second to the bends of B3 and B7 and to the terminals of the converter P _{2B of the} same name; for transformer T _C, one secondary winding is connected to the taps C2 and C6 and to the leads of the converter P _{1C of the} same name, the second one to taps C3 and C7 and to the leads of the converter of the same name P _2C . The primary windings of the transformers are connected to the inputs of _1A , _2A , _1B , _2B , _1C and _2C and the _control board.

The secondary windings of linear current transformers TT _A , TT _B and TT _C , as well as phase current transformers TT _AB , TT _BC and TT _CA , are connected to the bushings on the tank cap.

The reactor operates as follows.

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

For the reactor to operate in the first extreme mode of minimum power - idle mode - it is necessary that there is no magnetization of the cores of the magnetic circuit. This provides the control system SU by shorting the inputs U _1A- U _2A , U _1V- U _2V and U _1C- U _2C . Since the isolation transformers T _A , T _B and T _C are in this case in the 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 are shorted in pairs. In this case, each of the transducers P _1A and P _2A , P _1B and P _2V , P _1C and P _2C is practically shorted, and there is no magnetization of the magnetic core rods.

For the reactor to operate in the second extreme mode - in the maximum power mode - the maximum, so-called full-period saturation of the rods is necessary. In this case, the SU bends U _1A- U _2A , U _1V- U _2V and U _1C- U _2C disconnects. In this case, the diodes D of the converters P _1A , P _2A , P _1V , P _2V , P _1C and P _{2C 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 , which puts isolation transformers in full-time saturation of the rods.

Intermediate modes from idle to maximum power are regulated by the control system according to a predetermined program or manual adjustment. In this case, the rated power mode, as a rule, is set for one of the characteristic 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.

The implementation of the Converter installed in the circuit of the partitioned winding of each rod in the form of two chains with two diodes, provides an increase in the reliability of the reactor compared with the known solution. This is ensured, firstly, by optimizing the operating conditions of each diode and, secondly, due to the fact that when one diode fails, the reactor does not accidentally disconnect from the network and can be operated for a long time until the scheduled repair with replacement of the converter.

Isolation transformers installed between the control system and the converters ensure 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 average horizontal yoke of the magnetic circuit 13 has sections 14 and 15 of a reduced section of steel. The first function of these sections is to expand the limits of reactor power control. The size of the sections of the reduced steel section should be minimal; when designing the reactor, it is selected from the technological capabilities of production. The ratio of the values of sections of a reduced cross-section in the extreme sections of the average yoke Δ _extreme. and in the middle sections of the average yoke Δ _average. must be within:

1.5 <(Δ _average / (Δ _extreme ) <3.

The use of sections of reduced cross-section with the optimal choice of the ratio of the values of these sections allows us to obtain a favorable distribution of magnetic induction over the rods, yokes and shunts, as well as to obtain the minimum consumption of steel at the maximum efficiency of shunts from the point of view of unloading the main magnetic circuit of the reactor and reduce additional losses in structural elements and the wall tank. This is explained by the fact that magnetic fluxes in parts of the average yoke depend on the ratio of the values of sections of a reduced cross section in the extreme and middle sections of the average yoke in the no-load mode, and scattering fluxes in load modes as well. The upper limit cannot be exceeded, otherwise the magnetic fluxes and magnetic inductions in the extreme parts of the magnetic system will be underestimated, and in the middle - overestimated. The lower limit must also be observed, otherwise magnetic fluxes and magnetic inductions will be overestimated in the middle parts of the magnetic system. Confirming results of calculating a mathematical model, if necessary, can be additionally presented.

The second function of sections 14 and 15 is to reduce the sound level (noise) and vibration of the reactor. Due to the presence of non-magnetic gaps in the known device, large electromagnetic forces acted on the reactor magnetic circuit — forces of magnetic attraction (due to the large magnetic induction in non-magnetic gaps). In the proposed reactor in areas of reduced steel section, electromagnetic forces are absent. This drastically reduces the noise and vibration of the reactor.

The high voltage reactor is oil-cooled. The extraction part — the reactor’s magnetic system (magnetic core and shunts with windings and press-fit structural elements) is located in the oil tank, and the reactor inlets are on the tank cover. Converters and isolation transformers are placed in the same tank on the assembly panel 21 (Fig. 1), 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, compared with analogues and prototype, the reliability is increased, the sound level in all modes is significantly reduced. The production of reactors is scheduled for the near future.

LITERATURE

1. Bryantsev A.M. "Electric reactor with magnetization." RF patent №RU 2324250, application: 2006145299/09, 12.20.2006. Published: May 10, 2008.

2. Bryantsev A.M. "Electric reactor with magnetization." RF patent №RU 2418332, application: 2010114824/07, 04/14/2010. Published: May 10, 2011.

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 are located, upper, lower and middle horizontal and two side vertical yokes, with horizontal yokes have two middle and two extreme parts, four magnetic shunts in the form of rectangular frames with horizontal and vertical sections, while The main 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 yokes, the reactor contains linear inputs and current transformers, semiconductor converters in the form of chains of parallel connected diodes and resistors, and a control system, the windings are connected to a three-phase network and to converters, three-winding isolation transformers installed between the converters and the control system, characterized in that additional converters are introduced into the reactor in the form of chains of parallel-connected diodes and resistors and phase current transformers, while each of the mentioned chains and the chain of the additional converter are connected at one end to the other through a phase current transformer, and at the other common end it is connected to a two-section winding, the average the horizontal yoke of the magnetic circuit is made with sections of a reduced steel section, the ratio of the values of sections of a reduced steel section in the extreme parts of the average yoke Δ _extreme and middle parts of the average yoke Δ _average. makes up
1.5 <(Δ _average / (Δ _extreme ) <3,
sections of a reduced steel section are made with alternating solid and cut sheets, and the fill factor with steel of these sections is K _app. is within
0.25≤K app _. ≤0.75.

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