RU84163U1 - CONTROLLED CURRENT LIMITING REACTOR (OPTIONS) - Google Patents

Abstract

1. A controllable current-limiting reactor containing at least one magnetic circuit, at least one network phase winding, divided into two identical half-phase windings, each located on its own section of the magnetic circuit and connected in series to connect between the phase output of the AC source and the load, and at least one control winding connected to an adjustable constant voltage source, characterized in that the half-phase windings are divided into an equal number of sections, placed each on its own magnetic core portion, wherein the semi-phase section each connected in parallel according to. ! 2. A controllable current-limiting reactor containing at least one magnetic circuit, at least one network phase winding, divided into two identical half-phase windings, each located on its own section of the magnetic circuit and electrically connected to each other to be connected between the phase output of the AC source and the load, and at least one control winding connected to an adjustable constant voltage source, characterized in that the half-phase windings are divided into an equal number of sections placed ach at its yoke portion, wherein different semi-phase winding sections are connected in series in pairs oppositely, forming the sectional branches connected in parallel.

Description

The invention relates to the field of electrical engineering, in particular to electric current-limiting reactors, and is intended in particular for use in electrical AC networks.

A well-known technical solution of a current-limiting reactor is a controlled saturable electromagnetic reactor: {[1], M.A. Rosenblat. Magnetic elements of automation and computer technology. "Science", Moscow, 1966. Fig. 7-1d, p. 239; Fig. 7-4, p. 248}. The disadvantage of such a limiting reactor is the complexity of the design when solving the problem of obtaining a small value of the voltage drop across the reactor in normal operating conditions, i.e. receiving high quality electricity.

Reactors are also known: {[2] USSR author's certificate No. 1164795, 1985}; {[3] RF patent No. 2132581, 1998}, in which the phase winding is partitioned, that is, divided into two half-phase windings. These reactors have the same disadvantages as the reactor [1].

Current limiting reactors are known: {[4] B.P. Raju and et al. A CURRENT LIMITING DEVICE USING SUPERCONDUCTING D.C. BIAS. APPLICATI-ONS AND PROSPECTS. IEEE Tr., No. 9, September 1982}; [5] US Pat. 4045823, 1977}; {[6] US Pat. 3671810, 1972}; {[7] US Pat. 4117524, 1978};

{[8] US Pat. 4257080, 1981}. They also have the disadvantages of the above reactors.

The closest technical solution to the current-limiting reactor, adopted as a prototype, is a reactor made as described in the publication [9], Pub. No .: US 2006/0158803 Al, Jul. 20, 2006.

This reactor contains a magnetic circuit, at least one network phase winding, divided into two identical half-phase windings, each located on its own section of the magnetic circuit and connected electrically in series between the phase output of the AC voltage source and the load, as well as control windings connected in series according to and connected to an adjustable constant voltage source.

The disadvantage of this limiting reactor is the insufficiently low voltage drop across the reactor and, accordingly, the low quality of electricity in normal operating conditions, high mass and dimensions.

The aim of the invention is to improve the quality of electricity by ensuring a low voltage drop across the reactor in normal operating conditions without compromising weight and size.

This is achieved by the fact that in a control controlled by a winding connected to an adjustable direct current source, a current-limiting reactor containing a magnetic circuit and a network phase winding, divided into two identical half-phase windings connected in series against each other and connected between the phase output of the alternating current source and by the load of the external circuit, these half-phase windings are divided into an equal number of sections. Each section is placed on a separate section of the magnetic circuit. In this case, the sections of the windings of each half-phase can be connected to each other in parallel, or the corresponding sections of the windings of different half-phases are connected pairwise in series in the opposite direction, forming sectional branches connected in parallel and connected between

phase output of the AC source and the load of the external circuit.

To clarify the invention, we consider a current-limiting reactor with three sections of half-phase windings.

Figure 1 shows a variant of the circuit of one phase of the proposed controlled current-limiting reactor with a parallel connection of the sectional windings of each half phase;

figure 2 shows a variant of a circuit with pairwise counter-series connection of the corresponding sectional windings of the half-phases;

figure 3 shows the waveform of the transient process of limiting the short circuit current (short circuit) in the load circuit.

The network phase winding of the controlled current-limiting reactor 1 is divided into two half phases 2, 3. The winding of the half phase 2 is divided into sections 4, 5, 6; the winding of the half-phase 3 is divided into sections 7, 8, 9. Each section is placed on its own section of the magnetic circuit, for example, on its core in a phase or three-phase magnetic circuit. In the embodiment shown in FIG. 1, the windings 4, 5, 6 and the windings 7, 8, 9 are connected together in parallel, forming two parallel groups of half-phase windings, connected in series with each other, and connected between the network 16 and the load 17.

In the embodiment of FIG. 2, the half-phase winding section 4 is connected in series with the half-phase winding section 7; section 5 of the semi-phase half winding is connected similarly with section 8 of the half-phase winding 3, and section 6 of the half-phase 2 by section 9 of the half-phase 3. The three branches of the network windings thus formed are connected in parallel to be connected between the network 16 and the load 17.

In the above versions of the reactor circuit, the control windings 10, 11, 12, 13, 14, 15 are individual and are located on each rod. The control windings 10, 11, 12 of the half-phase 2, and 13, 14, 15 of the half-phase 3 are connected in series according to. The network windings of the half phases are connected in series in the opposite direction between the network 16 and the load 17.

The control winding can be common to the half-phase (then the three-phase reactor has six control windings), or the control winding is common to the phase (then there are three control windings in the three-phase reactor design), or the control winding is common to the entire three-phase reactor design (then the control winding one for the entire three-phase reactor). All of these control windings are known and cited in the previously mentioned publications. The windings (winding) of the control are powered by a DC power source 18.

The connection schemes of the network windings of both variants of the circuit (Fig. 1 and Fig. 2) have identical external electrical characteristics, since the principle of operation of the reactors in both winding connection schemes remains unchanged. Under the electrical characteristics refers to the dependence of the inductance of the reactor on the network current and the control current.

The principle of operation of a controlled current-limiting reactor is as follows.

Network windings play the role of inductance, which varies depending on the magnitude of the network current. As long as the mains current is less than the specified value — the limiting current — the reactor is in a fully saturated state, the voltage drop across it is minimal (usually no more than 1-2% of the nominal mains voltage), which does not impair the quality of the electric power at the load. The magnitude of the limiting current, determined by the control current flowing through the control windings (winding), is usually selected more by 10-200% of the maximum possible normal load current. Therefore, in all normal operating conditions, the reactor has practically no effect on the operation of the load and the network. When in emergency conditions the network current tends to exceed the value of the limiting current (which occurs during short circuits in the load circuit - short circuit and during emergency overloads - SG), the reactor goes out of saturation, its inductance is significantly

increases, which prevents the rise of the emergency current above a predetermined value, almost equal to the value of the limiting current.

The proposed connection of the half-phase windings provides a low voltage drop in normal operating conditions and inertia-free current limitation in emergency conditions. Moreover, in emergency modes, the function of limiting the half-phase current is performed alternately - one half-period of the mains voltage is one half-phase, and the second half-period is the second.

The parameters of any current-limiting reactor are determined taking into account the requirements of the following two reactor operation modes:

- Requirement I. Emergency modes: Short circuit - short circuits, GHG - emergency overloads, accompanied by unacceptably high currents. In these modes, the reactor must absorb almost all the mains voltage in order to limit the magnitude of the emergency current at a given level. The current limit value is usually selected 10-200% higher than the maximum normal operating current.

- Requirement P. Normal operating modes. In these modes, it is required that the voltage drop across the reactor does not exceed the minimum possible values - usually no more than 1-2% of the nominal phase voltage of the network.

These two requirements are determined: the number of turns W of each network winding, the cross section of each rod S _{m of the} magnetic circuit (these are the main parameters of the reactor), etc.

Two design requirements are antagonistic to one another:

- Requirement I. In emergency conditions, the reactor must have a large (maximum possible) value of inductance,

- Requirement P. In operating conditions, the reactor must have a minimum permissible inductance.

As an illustration of the effectiveness of sectioning, as a means of achieving the objectives of the invention, we choose a toroidal reactor design. The choice of this reactor design does not violate the physical nature

processes and, in a general sense, does not contradict the subject of the invention, but allows for a more clear understanding to state the essence of the invention. According to {[10], P.L. Kalantarov, L.A. Zeitlin Calculation of inductances. L., "Energoatomizdat", 1986, pp. 169, 190 and 369}, as well as {[11], S. G. Kalashnikov. Electricity. M., "Science", 1985, pp. 190, 191 and 211} the inductance L of the reactor is determined by the expression:

L = ,(one)

where L is the reactor inductance, μ ₀ = 4π × 10 ^-7 GN / m is the magnetic constant, μ is the magnetic permeability of the rod material, W is the number of turns of the winding, d is the diameter of the middle turn of the winding, D is the average diameter of the toroid. Usually d ² ≪D ² . Then from (1) it follows:

L = . (2)

According to (2), in order to obtain the largest value of L (for emergency operation), it is necessary to increase μ, W, and d. And to obtain a small value of L (for normal operating conditions), it is necessary to choose D of a large value, and μ, W and d to decrease.

Emergency operation of the reactor requires the choice of the material of the magnetic circuit (the maximum possible value of μ), the required cross-sectional area of the rod (S _m ≈ ) and the required number of turns of the winding (W). From the law of electromagnetic induction ([11], p.182) it follows: Ψ = , (3)

where Ψ = S _m BW is the flux linkage (Ψ) equal to the product of the cross-sectional area of the rod (S _m ), induction B and the number of turns of the winding W. The magnetization reversal half-phase of the current-limiting reactor lasts half the network voltage period. Given this interval, from (3) we obtain:

B × S _m × W = , (four)

where U _m is the amplitude of the sine wave of the phase voltage of the network in volts, ω = 2πF = 314.159 p / s, F = 50 Hz. Expression (4), for μ and W selected, allows us to determine the diameter of the middle turn of the toroid winding d (since S _m ≈ )

In operating conditions, the current-limiting reactor is in a fully saturated state (μ = 1), its inductance is determined by expression (2), and it should be the minimum possible - satisfying the requirements of the minimum voltage drop. For this, the average diameter of the toroid D must be chosen large enough, since the number of turns W and the average diameter of the coil of the winding d are already selected from the emergency conditions and are expressed by finite values. The increase in D is expressed in a significant increase in the mass and dimensions of the current-limiting reactor of known design.

The proposed reactor with sectioning of the half-phase of the reactor and the proposed scheme for connecting its network sectional windings (parallel consonant connection of the sectional windings of the half-phases) allows us to obtain a small inductance of the half-phase of the reactor L (and therefore the phase and the entire reactor as a whole), because, according to the theory of electrical engineering [11] , really the following expression:

L = , (5)

where L is the inductance of the reactor half-phase, L _n is the inductance of the reactor half-phase section, n is the number of sections. From (5) it follows that the inductances of the reactor sections L _n can be chosen of a rather large magnitude and, therefore, with a rather small diameter of the toroid D and, therefore, with a rather small mass and dimensions. And, nevertheless, by choosing a sufficient number of sections n, it is possible to obtain the required small value of the resulting inductance L.

Below are the calculation results, which show that in the absence of the proposed sectioning, it is necessary to create a bulky reactor (the mass of the active materials of the reactor is estimated at 2719 tons, the dimensions of the three-phase structure with an external design of 25 m × 25 m × 3.5 m (h)).

Thus, the sectioning of the half-phases of the reactor can significantly reduce the mass and dimensions of the reactor while maintaining a small value of inductance in operating conditions. In the accepted calculation example of the proposed reactor with the number of sectors n = 10, the total mass of the proposed three-phase current-limiting reactor is estimated at 60 tons, and the overall dimensions for the outdoor installation of the reactor are 6 m × 6 m × 3 m (h). The proposed reactor has a low voltage drop in operating conditions and significantly lower mass and dimensions than the known current-limiting reactors. The objective of the invention is achieved.

As an illustration of the functioning of the proposed current-limiting reactor, Fig.3 shows the waveform of the transient process of limiting the short-circuit current in the load circuit. A computer mathematical model is compiled using the MATLAB Simulink software package. In the initial mode, the feeder load corresponds to the maximum operating mode. At the moment t = 19.91 s, a short circuit occurs. The oscillogram shows:

us is the network voltage in volts;

is - network current in amperes.

As follows from the waveform, the limiting reactor inertialessly, without the appearance of overcurrents, limits the current at a given level. The desired result on the efficiency of the current-limiting properties of the proposed reactor is confirmed.

To confirm the effectiveness of the proposed technical solution, below are the calculation results, which show that in the absence of the proposed sectioning, it is necessary to create a bulky reactor (the mass of the active materials of the reactor is estimated at 2719 tons, the dimensions of the three-phase design with an external design of 25 m × 25 m × 3.5 m ( h)).

Reactor initial requirements:

220 kV network, normal operating load current maximum 1 kA (1414 A amp.), Short circuit current of 15 kA (21213 A amp.), It is necessary to limit the current to 2 kA +/- 20% (2828 +/- 565.6 A amp .). According to these requirements, the limiting reactor must have an inductance of less than 4.05 mH in operating mode, and more than 40.5 G in the limiting mode. As cores, toroids from materials with BCPs (for example, types 50NP or 3407, 3408) without non-magnetic gaps were selected.

* The calculation results of a known embodiment of the reactor (prototype): W = 200 vit., D = 10 m, d = 1.6 m, the mass of three phases 2700 tons, dimensions 25 m × 25 m × 3.5 m (h), (outdoor installation).

** The calculation results of the proposed embodiment of the reactor: n = 10, W = 3OOO vit., D = 2 m, d = 0.13 m, weight 60 tons, dimensions 6 m × 6 m × 3m (h), (outdoor installation )

*** From a comparison of the results obtained, it follows that the sectioning of the rods and windings of the half-phases of the reactor, proposed in this application, is an effective means of obtaining a small voltage drop across the reactor, high quality electricity in operating modes, as well as obtaining small values of the mass and dimensions of the reactor.

Claims (2)

1. A controllable current-limiting reactor containing at least one magnetic circuit, at least one network phase winding, divided into two identical half-phase windings, each located on its own section of the magnetic circuit and connected in series to connect between the phase output of the AC source and the load, and at least one control winding connected to an adjustable constant voltage source, characterized in that the half-phase windings are divided into an equal number of sections, placed each on its own magnetic core portion, wherein the semi-phase section each connected in parallel according to. 2. A controllable current-limiting reactor containing at least one magnetic circuit, at least one network phase winding, divided into two identical half-phase windings, each located on its own section of the magnetic circuit and electrically connected to each other to be connected between the phase output of the AC source and the load, and at least one control winding connected to an adjustable constant voltage source, characterized in that the half-phase windings are divided into an equal number of sections placed ach at its yoke portion, wherein different semi-phase winding sections are connected in series in pairs oppositely, forming the sectional branches connected in parallel.