RU2416874C2 - Generator of input of signal currents to three-phase power transmission line - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: amplitude of signal current introduced to phases BC of 0.4 kV line to be compared in prototype and in the proposed method is the same and is equal to I_m=17A. The result is achieved by the fact that to the proposed generator containing 10/0.4 kV transformer the low-voltage windings of which are connected to input of double-wave rectifier bridge (bridge), resistor the second output of which is connected to the first input of controlled key, the first, the second capacitors, there introduced is air inductance coil the first output of which is connected to output of controlled key and the first armature of the second capacitor, the second armature of which is connected to phase B of 0.4 kV line, the second output of air inductance coil is connected to negative bus of bridge and to the first armature of the first capacitor, the second armature of which is connected to phase C of 0.4 kV line, and positive bus of bridge is connected to the first output of resistor.

EFFECT: consumption of power is reduced by 2,8 times without using air transformer.

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Description

The invention relates to the field of electrical engineering and can find application in organizing communication channels using three-phase power lines (0.4-35) kV without processing them with high-frequency chokes.

Achievable technical result - reduction of power consumption from the 0.4 kV line by 2.8 times.

The famous "Generator Tsagareishvili S.A. input signal currents into a three-phase electric network. "RU 2224370 C2 from 02.20.2004, Bull. No. 5. This generator has a drawback - high power consumption from the network of 0.4 kV.

Also known "Generator Gutina K.I. input signal currents into a three-phase power line ", which is taken as a prototype. RU 2224366 C2 of February 20, 2004, Bull. No. 5.

The disadvantages of the prototype

1. Large power consumed from the 0.4 kV network.

2. The presence of an air transformer that decouples the 0.4 kV line circuit from the rectified DC voltage circuits by a three-phase bridge (bridge). It should be noted that in an air transformer it is difficult to technologically obtain a coupling coefficient between the primary and secondary windings close to unity.

In the proposed technical proposal, the power consumption is reduced by 2.8 times without the use of an air transformer. The amplitudes of the signal current introduced into phases B and C of the 0.4 kV line for comparison in the prototype and in the invention are taken to be the same and equal to I _m = 17 A.

The task of the invention is to reduce power consumption from a 0.4 kV network by 2.8 times.

The technical result is achieved by the fact that in the proposed generator for inputting signal currents into a three-phase power line containing a transformer, the low-voltage windings of which are connected to the input of a half-wave rectifier bridge, a resistor, the second output of which is connected to the first input of the controlled key, the first and second capacitors, an air coil is introduced inductance, the first output of which is connected to the output of the controlled key and the first lining of the second capacitor, the second lining of which is connected to phase B izkovoltnoy line, the second output air inductor is connected to the negative bus bridge and the first plate of the first capacitor, the second plate of which is connected to the C phase low-voltage line, positive bus bridge connected to a first terminal of the resistor.

The drawing shows a diagram of a generator that implements the claimed technical proposal, which shows:

1 - transformer 10 / 0.4 kV - (transformer);

2 - three-phase power line 10 kV;

3 - three-phase power line 0.4 kV;

4 - three-phase two-half-wave rectifier bridge;

5. - air inductor;

6 - the first capacitor;

7 - second capacitor;

8 - resistor;

9 - managed key;

10 - control unit.

Define the power consumption from the line of 0.4 kV in the prototype, while the active resistances of the transformer windings 10 / 0.4 kV, the active resistances of the primary and secondary windings of the air transformer are neglected.

From the description of the prototype it follows that the amplitude of the current flowing along the circuit: point 1 of the bridge - the primary winding of the air transformer 5 - resistor 9 - key 10 - point 2 of the bridge is 17 A, while we assume that the transformation coefficient of the air transformer is equal to one.

The power consumption in the prototype, taking into account the assumptions adopted above, is equal to:

where I _m = 17 A is the amplitude of the current introduced into phases B and C of the 0.4 kV line;

R ₈ = 10 Ohms - the resistance of the resistor 8.

The coefficient 0.25 in (1) corresponds to the time of the closed position of the key, which is closed 0.25 T ₀ , while the power is consumed from the line 0.4. kV

The claimed generator works as follows:

we assume that the potential of phase A is greater than the potential of phase B in the considered time interval, in this case the darkened diodes of the bridge 4 will be opened. With the closed key 9, current will flow through the circuit: phase A-diode D1-resistor 8-key 9-air coil inductance 5-diode D5-phase B.

When current flows through the air inductor 9, electromagnetic energy will accumulate in it, which at the time of opening the key is equal to:

where I _m is the amplitude of the current at the time of opening the key 9

L is the inductance of the air inductor 5.

The key operation algorithm is adopted as follows:

where τ ₃ - the time interval of the closed position of the key;

- период частоты тока сигнала;

- period of the signal current frequency;

f ₀ is the frequency of the current of the signal introduced into phases B and C of the 0.4 kV line.

At time t = 0.18T _{0, the} key is opened, while due to the accumulated electromagnetic energy in the air inductor 5, a current of free oscillations occurs in the oscillatory circuit along the circuit:

capacitor 6-phase C-phase B-capacitor 7-air inductor 5.

The elements of the oscillatory circuit have values corresponding to resonance at a frequency f ₀

where C ₆ = C ₇ = 10 · 10 ^-6 F - capacitance of capacitors 6 and 7;

L ₅ = 5 · 10 ^-3 H - inductance of an air inductor 5.

The oscillation circuit is tuned in resonance to the signal current frequency f ₀ = 1000 Hz, provided:

Where

C ₆ = C ₇ = C;

C _∑ is the capacitance of the oscillatory circuit;

L is the inductance of the oscillatory circuit.

Due to the fact that the capacitors 6 and 7 are connected in series, the capacitance of the oscillatory circuit Sk is:

Taking into account (4), the inductance of the circuit is 5 · 10 ^-3 GN.

We determine the amplitude of the current that is introduced into phases B and C of the 0.4 kV line:

where E ₀ = 512 V is the constant component of the rectified three-phase two-half-voltage when it is expanded in a Fourier series;

R = 50 m;

L = 5 · 10 ^-3 H - the inductance of the coil 5.

Thus, the amplitudes of the currents introduced into phases B and C in the prototype and in the application are equal.

Define the power consumption in the invention by analogy with the prototype (1)

where I _m = 17 A is the amplitude of the current introduced into phases B and C of the 0.4 kV line. R ₈ = 5 Ohms - resistance of the resistor 8.

The coefficient 0.18 in (7) corresponds to the time of the closed position of the key when the energy from the 0.4 kV network is consumed.

2,8 раза при отсутствии воздушного трансформатора, как это было в прототипе.Thus, in the inventive generator, taking into account expressions (1) and (7), it can be argued that the power consumption in the application is less than

2.8 times in the absence of an air transformer, as it was in the prototype.

The result obtained is the fulfillment of the goal set in the claimed technical proposal.

Claims (1)

A generator for inputting signal currents to a three-phase power line, comprising a transformer, the low-voltage windings of which are connected to the input of a three-phase two-half-wave rectifier bridge, a resistor, the second output of which is connected to the first input of the controlled key, the control unit, the output of which is connected to the second input of the controlled key, the first and second capacitors, characterized in that an air inductor is inserted into it, the first output of which is connected to the output of the controlled key and to the first lining of the second the first capacitor, the second plate of which is connected to the phase in the low-voltage line, a second terminal air inductor is connected to the negative bus bridge and the first plate of the first capacitor, the second plate of which is connected to the C phase low-voltage line, positive bus bridge connected to a first terminal of the resistor.