SU1781711A1 - Three-phase saturating reactor - Google Patents

Description

The invention relates to static ferromagnetic devices intended, for example, to improve the operating modes of long-distance AC power transmissions, and having the ability to directly connect to the high-voltage line and ground the neutral of the primary winding.

The purpose of the invention is to simplify the design and reduce the material consumption of a three-phase saturable reactor by reducing the number of coils in the phase-shifting winding and reducing the cross-section of each yoke of the piping, reducing switching overvoltages by increasing the reactive power “consumed by the reactor in transient conditions, expanding its scope through regulation through external influences of the reactive power consumed by him.

Figure 1 shows a cross section of the active part of a three-phase saturable reactor; in Fig.2 is a partial section of a three-phase saturable reactor; in Fig.3 is a diagram of the windings of a three-phase saturable reactor; figure 4 - current-voltage characteristic (VAH) of a static reactive power compensator, consisting of a reactor and a constantly connected shunt capacitor bank; figure 5 - two longitudinal components of one rod with a coil to the clamps of which are connected two thyristors; Fig.6 is the natural current-voltage characteristic of HP and VAH, which corresponds to a greater reactive power consumed by the reactor; in Fig.7 - an additional combined reactor-autotransformer connected to the coil of the main three-phase winding; Fig. 8 is a single-phase block of a three-phase saturable reactor, the magnet wire of the block is armored, consisting of three O-shaped cores located radially and forming a three-beam symmetrical star in plan; figure 9 is also one single-phase block of a three-phase saturable reactor, the magnetic circuit of the block is made planar; figure 10 is an electromagnetic circuit of a three-phase saturable reactor, consisting of three identical modules; figure 11 is a cross section of one module of the reactor; 12 is a partial sectional view of one reactor module.

Three-phase saturable reactor contains a magnetically coupled magnetic circuit, the main three-phase winding, compensation and phase-shifting windings, the coils of which are located on the rods (Fig.1, 2 and 3). The magnetic core of the reactor consists of nine rods 1, 2, 3, ..., 9, which are divided into three groups of rods. The first group of rods includes rods 1, 2, 3, the second group - rods 4, 5, 6 and the third group - rods 7, 8, 9. The rods of each group of rods are closed from the ends by two common yokes 10, and the cross section of each yoke is 0.85 - 0.88 of the total cross section of three rods of the same group. Each phase of the main three-phase winding consists of one coil 11, the phases are connected to a star with the zero point 0. Each phase of the compensation winding consists of one coil 12, the phases are connected into a triangle, the circuit of which is grounded. Each phase of the phase-shifting three-phase winding consists of two parallel branches, which relative to the beginnings of az, bz, sz of these phases are connected counterclockwise. Each parallel branch consists of two coils 13 and 14, the ratio of the number of turns of kbFora X’sё'СТ is 0.532:; 1, respectively. These pairs of coils 13 and 14 are interconnected in a zigzag pattern. The phase-shifting winding has two neutral neutrals Οι and Oz. Each rod 1,3, 4, 7 and 9 is covered concentrically by two coils 13 and 14, which belong to different phases of the phase-shifting winding (Fig.1,2 and 3). Three coils ^ of the compensation winding cover each one of its three groups of rods. The same groups of rods are covered by coils 11 of the main three-phase winding (Fig.1 and 2).

A saturable reactor (HP) operates, for example, in a static reactive power compensator (SCR) circuit as follows. SCRM consists of HP and a constantly-on shunt capacitor bank. HP regulation is carried out by changing the saturation of the cores of the magnetic circuit, which depends on the voltage value of the electrical system with respect to the operating voltage range of the SCRM, limited by points 1 and 2 on the A.A. SCRM (figure 4). If the voltage of the electrical system is C ₃ .s. = U1, then all the reactive power Q _c generated by the shunt capacitors enters the network. Moreover, the inductive power Qi consumed by HP is zero. Suvelicheniem C _e .c. part of the power generated by capacitors is consumed by HP. When Tse.s. = Uy (Uy is the voltage of the SCRM setpoint), then Qc = Qi. When Us.c. > Uy HP continues to absorb reactive power.

Phase shifting winding (coils 13 and

14, see Fig. H) provides a shift of the vectors of the first harmonics of the magnetic flux in the rods with adjacent numbers by 40 °. The compensation winding (coils 12, see Fig. 3) filters out the 9th harmonic from the induction of the magnetic field, which turns into tension. The current of this harmonic flows along the circuit of this winding in the short circuit mode. The presence of phase-shifting and compensation windings causes the exclusion from the current of the main three-phase winding (coil 11, see figure 3) 3,5,7,9,11,13 and 15 higher harmonics, as well as a significant reduction of 17 and 19 harmonics. The absence in the current of the main three-phase winding of multiple harmonics of three allows you to Earth neutral About this winding and it can be directly connected by terminals A, B, C to a high-voltage power line (without an intermediate transformer). Since the 9th harmonic of the current is short-circuited in the compensation winding circuit, its circuit can also be grounded (Fig. 3). The coils 12 of the compensation winding physically separate the coils 11 of the main winding from the coils 13 and 14 of the phase-shifting winding (FIGS. 1 and 2). In this case, the compensation winding serves as a grounded shield for the main winding and thereby improves the operation mode of its high-voltage insulation. Phase shifting and compensation windings, along with the above functions, can also play the role of secondary and third windings, and the main winding is the primary winding of the transformer, therefore, in the developed device, the functions of the reactor and the functions of the power transformer are combined.

To limit switching overvoltages due to an increase in the reactive power of the reactor in transient conditions, the thyristor 15 is connected to the phase-shifting winding neutrals Οι and Og of the phase-shifting winding • on which the third harmonic voltage is applied (Fig. 3) and this voltage is rectified. As a result, a rectified third harmonic current will flow through the coils of the compensation winding, which will magnetize the rods 1 and 3.4 and 6.7 and 9 of the magnetic circuit. During the transient process, a free magnetic flux arises in the indicated bias circuit, which will also magnetize the system, which together will result in an increase in the reactive power consumed by HP in the first periods of the transient process and, accordingly, limitation of switching overvoltages.

As soon as the switching overvoltage is eliminated at the beginning of the transient process, the ignition angle of the thyristor 15 is changed accordingly at the right time (Fig. 3) and thereby the magnetization of the magnetic circuit with direct current is stopped (or reduced), and, consequently, the reactor consumes transient reactive power (at the ignition angle of thyristor 15 is 0 °, it is open and works like a diode, with an ignition angle of 90 °, the thyristor is closed and no current flows through it, which is equivalent to the absence of a thyristor).

To expand the scope of HP application by regulating by means of external influence the reactive power consumed by it, the reactor has magnetizing windings 17, thyristors 18 and 19 (Fig. 5), divided into two longitudinal parts, rods 2.5 and 8, on which there are no phase-shifting windings. The cross section of one part of the divided rods is equal to the cross section of the undivided rods 1, 3, 4, 6, 7 or 9, and the cross section of the other part is 0.4 0.33 of the cross section of the first. Thyristors 18 and 19 are connected counter-parallel and connected to the terminals of the magnetizing windings 17, which are mounted on the smaller parts of the divided rods. Regulation of reactive power of HP through external exposure is achieved as follows.

If both thyristors 18 and 19 are fully open (the ignition (regulation) angle of the thyristors is 90 °), then no current flows through the coils 17. In this case, HP operates at point 1 of the current-voltage characteristic, which is natural (Fig.6).

If both thyristors 18 and 19 are closed, the ignition (regulation) angle of thyristors is 0 °, then τόκ of a short circuit flows through coils 17. This current creates a magnetic field directed towards, within the smaller longitudinal component of the rods 2, 5 and 8, the magnetic field resulting from the combined action of other windings NR, which leads to an increase in magnetic induction in the sections of the rods of the magnetic circuit, not covered by coils 17. The latter is accompanied by an increase current in the main three-phase winding HP and the transition to point 2 of the other current-voltage characteristics of HP (Fig.6). At the same time, the reactive power consumed by HP also increases. By changing the ignition angle of thyristors 18 and 19 from 90 ° to 0 °, it is possible to adjust the reactive power consumed by HP from the value of the corresponding natural VA.h. it to the maximum value.

The above process is used, for example, to compensate for the charging power of power lines. For this, the ignition angle of thyristors 18 and 19 must be set equal to [.. or close to 0 °.

The circuit shown in FIG. 5 is also used to limit the switching overvoltages that occur in the initial period of the transition process. In the transient process, thyristor 18 (or 19) is closed (the ignition angle is 90 °), which is equivalent to its absence, and thyristor 19 (or 18) is open (its ignition angle can be adjusted) and acts as a diode (with an ignition angle of 0 °) . As a result

emf Induced by an alternating magnetic field in the coils 17 is rectified and a rectified current flows through them which magnetizes the system, and the reactive power consumed by HP increases in this case, which ensures the limitation of switching overvoltages. The number of turns in the coil 17 (Fig. 5) is selected both by the condition of creating the ppm of the corresponding value, and based on considerations of reducing the cost of the thyristor unit. The cross-sectional value of the second longitudinal component of the rods 2, 5 and 8 is adopted based on the need to obtain the desired control range.

In addition, to expand the scope of the reactor, it has additional single-phase combined autotransformer reactors (Fig. 7). In this case, the phases of the main winding (coil 11) of the reactor are made of two parts, between which autotransformer reactors are connected to the terminals Ai and Ar, Bi and Br, Sch. and Cr.

Figure 7 shows one of the groups of rods 1, 2 and 3. of the HP magnet line and coil 11 of phase A-X of its main three-phase winding (compensation and phase-shifting winding coils. Not shown), which is connected by an autotransformer circuit. Phase A-X correspond to the higher voltage and the _HV and the average voltage U _C n. Other phases of the main three-phase winding (not shown in Fig. 7) are connected in the same way, which are connected to each other in a star, and its neutral is grounded. Between the turns of the HP autotransformer winding, which belong only to the primary side, and the turns of this winding, which are common to both the primary and secondary sides, an additional autotransformer (DAT) of small power is connected in series, which is combined with a controlled reactor, and regulation is carried out by means of a thyristor 23 and diodes 24 and 25. In the DAT circuit, the turns of the coil 20 belong only to the primary side, the turns of the coils 21 and 22 belong to the primary and secondary sides, the number of turns of the coils 21 and 22 are mutually are equal. The transformation ratios of the main reactor winding, which is connected by an autotransformer circuit, and the DAT windings are equal.

The regulation of the reactive power of the reactor through external action is achieved as follows (Fig.7). ·

Thyristor 23 is closed, which is equivalent to its absence, i.e. no current passes through the thyristor. When the potential of the Oz point is greater than the potential of the X point (positive half-wave), then the current I flows through the coil 21 and diode 24 (no current flows through the ps coil 22). This rectified current creates a constant magnetic flux, which saturates the DAT magnetic circuit, the voltage on the windings of the latter decreases, and on the HP winding increases (voltage redistribution occurs), and therefore the magnetic induction in the terminals of the HP magnetic core increases, its current in the main winding also increases, and therefore , increases the consumed HP reactive power.

Thyristor 23 is also closed, i.e. no current flows through the thyristor, but the potential of the Oz point is less than the potential of the X point (negative half-wave). In this case, the current flows through the coil 22 and the diode 25 (no current flows through the coil 21). This rectified current (as well as with a positive half-wave) creates a constant magnetic flux saturating the DAT magnetic circuit. Therefore, (as in the previous case), the voltage across the windings of the latter drops, but on the winding HP increases and HP will continue to consume reactive power of the same magnitude as with the positive half-wave and closed thyristor 23..

Thyristor 23 is fully open, i.e. current may flow through it. In this case, with a positive half-wave, the current will flow through the coil 21 and coil 22, as well as through the thyristor 23 and diode 24. When the negative half-wave, the current will flow through the diode 25, thyristor 23, as well as through the coil 21 and coil 22 With a positive half-wave, the current flows along the indicated coils in the same direction, and with a negative half-wave the current flows along these coils in the opposite direction, that is, alternating current flows through coils 21 and 22. Therefore, the DAT magnetic circuit is not magnetized by a constant field and the voltage on its windings increases, and on the main winding HP decreases. The induction in the terminals of the magnetic core HP and the current in the main winding of it, and hence the reactive power consumed by Η P, are also reduced. When the ignition angle of thyristor 23 is changed from 90 ° to 0 °, a smooth regulation of the reactive power consumed by HP is achieved from a maximum value to a certain minimum value.

When performing the main winding of the reactor using an autotransformer circuit, the transformer with on-load tap-changer becomes ’unnecessary, since the voltage regulation function is performed by a power AT, which is combined with the reactor, and an additional AT (DAT), (Fig. 7). This DAT, with thyristor 23 open, is involved in the process of energy transfer from one side of the power AT to the other, and the power AT provides (92 - 86%) of the transmitted power, and the DAT, respectively (8 - 14%). DAT power is determined by the necessary range of reactive power regulation.

At high capacities, it is advisable to implement a three-phase saturable reactor on the basis of three single-phase identical blocks. In Fig.8 shows a block with a spatial magnetic circuit, and in Fig.9 with a planar. The magnetic core of a spatial design consists of three separate 0-shaped cores, lined or twisted. In addition, these cores can be lapped and magnetically connected by common yokes 16, while the yoke plates are made curved at an angle of 120 °, and the axis of the bend is parallel to the axis of the block. The magnetic circuit of the planar design of a single-phase unit (Fig.9) consists of. two groups of rods (the same as those discussed above, FIGS. 1 and 2) closed by common yokes 10. The primary winding phase is made of two coils, the direction of winding of these coils is opposite and each of them covers one of two groups of rods. These coils are connected in parallel so that a circulating magnetic flux is formed in the magnetic circuit of each single-phase unit (Fig. 9). At very high HP capacities, the magnetic core of the planar design of a single-phase unit can be made to reduce its height with lateral longitudinal yokes.

At very high powers and ultrahigh voltages, each composite reactor rod (it includes a group of rods 1, 2, 3 or 4, 5, 6 or 7, 8, 9, see Figs. 1, 2, and 3) with coils 11, 12 , 13, 14, it is advisable to perform in the form of an armored core with these windings (see, respectively, modules 1, 2 and 3 in Fig. Yu). Such an armored core consists of three rods (for example 1, 2, 3) and two end and two side yokes (Fig. 11 and Fig. 12). The winding 11 of each phase of the primary · winding is made up of three series-counter-connected coils, and each coil covers a cross section of one of the three rods (for example 1, 2 or 3), from the point of view of creating the magnetomotive force of the rods, these three coils are equivalent to one the coil of the phase of the primary winding, covering the cross sections of the components of one composite rod (see Fig. U and Fig.Z). In the same way as each phase of the primary winding 11, each phase of the compensation winding 12, i.e. and it consists of three sequentially connected coils. The reactor implemented according to the scheme shown in Fig. U consists of three identical modules (the design of one module is shown in Fig. 11 and Fig. 12), which are interconnected only galvanically. It is obvious that the manufacturing technology of serial power ^; autotransformers (transformers). The modular principle of the reactor, implemented in Figs. 8, 9, 10, 11 and 12, also allows to significantly reduce the power of the emergency reserve. When performing the primary winding in an autotransformer circuit, an additional single-phase autotransformer is connected to each pair of terminals Ai and Ar, Bi and Br, C) and Cr (Fig. 10). combined with a controlled reactor (Fig.7).

Claims (5)

Claim 1. A three-phase saturable reactor containing a nine-core magnetic circuit in the form of three groups of three rods in each, located on the magnetic circuit: a three-phase main winding connected in a star and a compensation winding connected in a triangle, each of which contains one coil per phase, ' covering a group of rods, phase-shifting winding, containing several coils in each phase with unequal numbers of turns, each coil of this winding covering one of the rods of the group, characterized in that, in order to simplify the design and reduce material consumption, each phase of the phase-shifting winding is made of two identical pairs of coils with a ratio of the number of turns of coils of one pair 1: 0.532, these pairs of coils connected in two parallel branches, connected opposite to the beginning of the phase, located on two phase rods, all phase-shifting coils are connected in a double zigzag pattern with two neutrals, and the group rods are closed by two common longitudinal yokes. 2. The reactor according to claim 1, characterized in that the cross section of each yoke is 0.85-0.88 of the total cross section of three rods of the same group. 3. The reactor according to claims 1 and 2 is distinguished by the fact that, in order to reduce switching overvoltages by increasing the reactive power in transient conditions, a thyristor is inserted into it, connected between the neutrals of the phase-shifting winding. 4. The reactor according to claims 1-3, characterized in that, in order to expand the scope of its application, it has magnetizing windings, thyristors, rods divided into two longitudinal parts, on which there are no phase-shifting windings, and the cross section of one part of them is divided the rods is equal to the cross section of the undivided rods, and the cross section of the other part is equal to 0.4 - 0.33 of the first thyristor section are connected in parallel and connected to the terminals of the magnetizing windings mounted on the smaller parts of the separated rods. 5. The reactor according to claims 1 to 4, characterized in that, in order to expand the scope of its application, it has single-phase controlled autotransformer reactors, the phases of the main winding are made of two parts, between which autotransformer reactors are connected. 1 2 3 4 5 6 7 8 9 13.14 - 13.14 _t II Figure 1 Figure 2 FIG. 4 rod 2.5 and 8 In the longitudinal component of the rod D longitudinal component of the rod Figure 5 [ J • o— A A 24? ife an additional autotransformer combined with a controlled reactor. G --- “I I / _; | σ> CH i 0-4— <· I ’I I I S. ^ ^: I ^A u EZZ tZZ (ZZ EZZ 'CZj czd rzd P X Fi 2.7 FIG. 9 Oh Oh FIG. 10