RU2451353C1 - Three-phase magnetisation-controlled reactor - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: reactor comprises an electromagnet part, converters with controlled rectifiers and supplied transformers according to a number of phases and a system of automatic control. The electromagnet part comprises a magnetic conductor with six rods, at least two for each phase of the circuit, with circuit windings, and control windings divided into parts, connected with inlets and outlets of converters. Parts of control windings in each phase of two rods are connected into four-armed bridges. Secondary windings of transformers are connected to inlet of controlled rectifiers, the outlets of which are connected with one diagonal of the bridge. The reactor comprises additional controlled rectifiers according to a number of secondary windings. Inlets of converters are connected with control windings of neighbouring phases, secondary windings of supply transformers are arranged with a different number of turns with the ratio of 1<w₂/w₁<10, where w₁ and w₂ - the number of turns of the secondary windings of the supply transformers. The technical result consists in increased reliability due to redundancy of a magnetisation system that reduces the time of reactor disconnection from the grid in case of scheduled revisions or repairs. Increased voltage at the outlet of the rectifiers for forcing due to increased number of the winding turns simplifies control of thyristor firing angles with the automatic control system.

EFFECT: reliability is increased by reduction of probability of a short circuit due to reduction of inputs at converters.

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Description

The invention relates to the field of electrical engineering, in particular to high-voltage regulated electrical complexes, and can be used in high-voltage electrical networks with a voltage of 110 ÷ 750 kV to compensate for reactive power and voltage stabilization.

At present, magnetically controlled reactors [1], which are a new type of controlled power inductance, are becoming more widespread in the domestic energy industry.

A known analogue is a three-phase magnetization controlled reactor [1], containing an electromagnetic part, a converter with a controlled rectifier and a supplying three-phase two-winding transformer having a primary and secondary windings on each rod. The electromagnetic part contains a magnetic circuit with rods on which network windings connected to a high voltage network are located, and control windings. The control windings are connected to the converter. The known reactor has several disadvantages, including the ability to control power only simultaneously in all phases. However, in some cases (unbalanced load, single-phase faults and shutdowns, OAPV - single-phase automatic reclosing), separate phase-by-phase regulation is necessary.

Partially, the disadvantages of the reactor according to [1] are eliminated in another reactor [2], which is a prototype. It also contains an electromagnetic part, which is made with a magnetic circuit with rods on which there are network windings connected to a high voltage network, and control windings, divided into parts and in each phase of two rods included in the four-arm bridges. There are three converters with controlled rectifiers and supply double winding transformers. In the prototype reactor, separate (phase) power control is carried out. However, there are drawbacks - the difficulty in ensuring the magnetization forcing in the speed dial and power reset modes, the insufficient reliability, because when the rectifier thyristors fail, it is necessary to disconnect the reactor from the network for a long time.

The aim of the invention is to eliminate these disadvantages, increase reliability and increase the functionality of the reactor.

This goal is achieved by the fact that in a three-phase controlled magnetization reactor containing an electromagnetic part, converters with controlled rectifiers and supply transformers in the number of phases having primary and secondary windings, and an automatic control system, the electromagnetic part containing a magnetic circuit with six rods, two for each phase of the network, on the rods are the network windings and control windings divided into parts, while the control windings are connected to the converters, parts control windings in each phase of two rods are included in four-arm bridges, converters have inputs and outputs connected to control windings, secondary windings of supply transformers of converters are connected to inputs of controlled rectifiers, and outputs of controlled rectifiers are connected to one diagonal of the bridge, additional controlled rectifiers are introduced into the reactor by the number of secondary windings of supply transformers. The supply transformers are multi-winding, the inputs of the converters are connected to the control windings of adjacent phases. The secondary windings of the supply transformers are made with a different number of turns, while their ratio

I <w ₂ / w ₁ <10,

where w ₁ and w ₂ are the number of turns of the secondary windings of the supply transformers.

The proposed reactor is illustrated by drawings. Figure 1 shows a diagram of a reactor with four converters and six-winding supply transformers in each phase. Figure 2 shows a diagram of a controlled reactor with two converters in the bias system of each phase and supplying four-winding transformers.

In Fig.1, a three-phase controlled magnetization reactor contains an electromagnetic part 1 and converters 2 for magnetization.

The electromagnetic part is a transformer device containing a magnetic circuit, burdened from electrical steel, with six rods 3-8, on which the windings are located.

Each phase A, B and C of the reactor has two rods with the network windings (CO) 9-11 covering them and the control windings (OS). On each rod the OS has two parts: 12-13, 14-15, 16-17, 18-19, 20-21 and 22-23.

Each of the three phases of converters 2 contains four controlled rectifiers 24-27, 28-31 and 32-35, one transformer supplying these rectifiers: 36, 37 and 38. The supply transformers have primary windings with the same number of turns (39-40, 41 -42 and 43-44) and secondary windings (45-48, 49-52 and 53-56). The secondary windings of the supply transformers are made with a different number of turns: the windings 45 and 47, 49 and 51, 53 and 55 have the number of turns w ₁ , and the windings 46 and 48, 50 and 52, 54 and 56 have the number of turns w ₂ , in 1 ÷ 10 times the number of turns w ₁ .

The three-phase controlled magnetization reactor includes a system for automatic control of rectifiers (not shown in the diagrams).

The windings of the CO reactor are included in the "star with zero" circuit and are connected to the network inputs A, B and C and zero input 0.

Each of the four parts of the winding of the op-amp of the reactor of each phase is the arm of the four-armed bridge, for example, the parts of the op-amp of the phase A 12, 13, 14 and 15 are the bridge. The diagonal of the alternating current of each bridge is connected to the inputs of the reactor a, b and c. The bridges are connected in a triangle pattern. The diagonal of the direct current of each bridge is connected to the inputs of the reactor + AB, -AB, + BC, -BC, + CA and -CA. These inputs are simultaneously the inputs of the transducers 2.

In Fig.1, the reactor is made with an electromagnetic part 1, the rods of the magnetic circuit of which 3-8 can have an oval cross section, with two rods of each phase located side by side and covered by one CO 9, 10 and 11. It is possible that the rods have a round cross section, and each rod is covered by a CO section, while two sections of each phase can be connected in parallel with each other.

Each of the three phases of the relatively small power converters 2 of the reactors may contain not four, but two controlled rectifiers 24-25, 28-29 and 32-33 (figure 2). In this case, the supply transformers 36, 37 and 38 are made of four-winding and have two secondary windings 45-46, 49-50 and 53-54. In this case, the windings 45, 49 and 53 have the number of turns w ₁ , and the windings 46, 50 and 54 have the number of turns w ₂ , 1 ÷ 10 times the number of turns w ₁ .

Three-phase controlled magnetization reactor (figure 1), made in accordance with the formula of the invention, operates as follows.

The inputs A, B and C of the reactor are connected to a three-phase AC electric network. Moreover, in all rods 3-8 there is an alternating magnetic flux. Three phase network phase voltages are shifted to each other by an angle of 120 °, so the transformed voltage to create a three-phase system OS line voltages on the inputs a, b and c (U _AB, U and _Sun U _ca). In the bridge circuit, on one of its diagonal between the inputs + av and -av, the alternating voltage of the fundamental harmonic, which is transformed from the network windings, is absent due to full magnetic symmetry. Similarly, there is no alternating voltage between the inputs + sun and -vc, + ca and -sa. This is used to magnetize the rods from the side of these diagonals of bridges. Between the other input AC voltages are, for example, between inputs of adjacent phases + Sun + and Ca, and also between neighboring entries of the same phase and -BC -sa voltage equals 0,5 U _ca. These alternating voltages are used to power phase A converters as input voltages on the transformer primary windings. In the same way, the voltages at the inputs of the windings of the op-amps of adjacent phases are used to power the phase inverters B and C.

Reactor power is controlled by magnetizing the rods with direct current. This direct current arises as a result of the operation of converters 2.

In the case when the control angles of the thyristors of all controlled rectifiers 24-35 are zero, the rectifiers are in a mode in which a direct current is not generated by the reactor, rods 3-8 are not magnetized, and the reactor is in idle mode.

At other control angles of the thyristors, the rods become magnetized, and the rods become saturated during a certain fraction of the period. Reactive current flows in the windings, which the reactor consumes from a three-phase network.

Thus, the reactor controlled by magnetization, depending on the value of the DC component in the current of the windings, can be in the nominal mode, the maximum possible load mode, or in intermediate steady-state and transient load modes.

In steady-state modes, controlled rectifiers 24, 26, 28, 30, 32, and 34 work.

Rectifiers 25, 27, 29, 31, 33, and 35 operate in transient modes (power gain or discharge). Since the condition 1 <w ₂ / w ₁ <10 is fulfilled, the output voltages of these rectifiers are increased in comparison with the voltages of steady-state rectifiers 24 , 26, 28, 30, 32 and 34 (in the limit of 20 times, because in the circuit in figure 1, the rectifiers are connected in series). Such a voltage boost provides the necessary reactor speed.

The operation of the reactor in figure 2 is similar to the considered operation of the reactor in figure 1. The difference is that in repair conditions, if it is necessary to replace the damaged thyristors of one of the controlled rectifiers, when one of the rectifiers is turned off, the function of the disconnected rectifier can be taken over by the second rectifier. For example, when the steady-state rectifier 24 is turned off, the rectifier 25 takes over the function of ensuring the operating mode, which will work at other opening angles of the thyristors.

To increase reliability, additional redundancy is possible - the implementation of two sets of converters with controlled rectifiers and supply transformers.

Compared with the prototype and analogues of the proposed reactor has several advantages. Reliability of operation has been significantly increased, since the introduction of additional rectifiers and the use of multi-winding transformers actually provide redundancy of the magnetization system without increasing the number of transformers. The redundancy of this system drastically reduces the time the reactor is disconnected from the network in the event of scheduled revisions or emergency repairs with the replacement of failed thyristors. In addition, the input voltage of the rectifiers for boosting 25, 27, 29, 31, 33 and 35 increases due to the greater number of turns of the windings (due to the fulfillment of the ratio 1 <w ₂ / w ₁ <10 and due to the series connection of two rectifiers). This allows us to significantly simplify the algorithm for controlling the ignition angles of thyristors by an automatic control system. Ability to simplify the design of transformers is obtained at the expense of halving the input voltage compared to the line voltages _AB U, U and _Sun U _ca. An additional increase in reliability was obtained by reducing the likelihood of short circuits due to the reduction in the number of inputs on the converters (in the prototype, the number of inputs is nine, and in the proposed device is six).

The performance of the proposed bias-controlled electric reactor and its high technical and economic indicators are confirmed by calculations, mathematical and physical (on mock-ups) modeling.

Literature

1. Bias-controlled electrical reactors. Sat articles. Ed. doctors of those. sciences prof. A.M. Bryantseva. - M: “Sign”. 2004, p. 211-232.

2. Bryantsev A.M., Dolgopolov A.G., Lurie A.I., Bazylev B.I., Ukolov S.V., Zaitsev A.I., Sokolov Yu.V., Akhmetzhanov N.G. For the first time in a 500 kV network, a magnetically controlled shunt reactor with a capacity of 180 MVA was commissioned. Electricity, No. 8, 2006, pp. 65-68.

Claims (1)

A three-phase magnetization controlled reactor containing an electromagnetic part, converters with controlled rectifiers and supply transformers in the number of phases having primary and secondary windings, and an automatic control system, the electromagnetic part containing a magnetic circuit with six rods, two for each phase of the network, located on the rods network windings and control windings divided into parts, wherein the control windings are connected to the converters, parts of the control windings in each phase of two rods are included in the four-arm bridges, the converters have inputs and outputs connected to the control windings, the secondary windings of the supply transformers of the converters are connected to the inputs of the controlled rectifiers, and the outputs of the controlled rectifiers are connected to one diagonal of the bridge, characterized in that the additional controlled rectifiers are introduced into the reactor by the number secondary windings of supply transformers made by multi-windings, the inputs of the converters are connected to the control windings of adjacent phases, secondary winding supply transformers made with different numbers of turns, and their ratio

,
where w ₁ and w ₂ are the number of turns of the secondary windings of the supply transformers.

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