RU2115238C1 - System of signal transmission and reception over wires of three phase transmission line - Google Patents

Abstract

FIELD: electrical engineering. SUBSTANCE: system may be used to form communication channel at voice frequencies over lines of 0.38-10-35 kV without their high-frequency processing. Dispatching and controlled stations of system have transformers of 6-10/0.4 kV, first and second filters, telecontrol, telesignalling and telemeasuring unit, transmitter, first and second balance phase detectors, local oscillator, phase inverter, current transformer, and shunting element. EFFECT: transmission of information over synchronous communication channel. 1 dwg

Description

 The invention relates to telemechanics and can be used to transmit and receive television signals through the wires of a three-phase power line.

 The known telemechanics system TMRS-10 for distribution networks of 6 - 10 kV. THOSE. Georgievskaya, R.A. Gozhansky, K.I. Mityushkin. Real-time tele-information systems for dispatch control of power systems.

 Collection of scientific works of VNIE, 1985, pp. 120 - 124.

 The disadvantages of this system include the lack of the ability to transmit telemetry information from controlled points. Closest to the technical nature of the claimed system is a system for transmitting and receiving signals through wires of a three-phase power line, as SU 1377481, H 04 B 3/54, 1992

 The disadvantages of this system include the loss of its operability in the presence of 0.38 kV capacitor banks in the network, which serve to increase cosφ. .

 The claimed system solves the technical problem of eliminating this drawback.

 A system for transmitting and receiving signals through wires of a three-phase power line (System) (see drawing) 1 contains at the control room (DP) 1 a power line 2, a supply transformer 3, a medium voltage line 4, a transformer 5, a capacitor bank 6, the first 7, second 8 filters, telecontrol unit (TU), telealarm (TS), telemetry (TI) 9, transmitter 10, first 11, second 12 balanced phase detectors, local oscillator 13, phase shifter 14, current transformer 15, shunt element 16 at controlled point 17 (KP), transformer 18, first 19, the second filter 20, TU unit, TC, TI 21, a transmitter 22, a first 23, a second balanced phase detectors 24, a local oscillator 25, phase shifter 26, a capacitor 27, a current transformer 28, the bypass element 29.

 The system works as follows.

,
где
I_m - амплитудное значение токов сигналов;
ω₁= 2πf₁ - верхняя частота;
ω₂= 2πf₂ - нижняя частота,
при этом выполняются условия:
f₁ - f₂ = 2F,
где
F - частота промышленного напряжения.When transmitting signals from DP 1 to KP 17 from the TU, TS, TI 9 block, trigger pulses are received at the input of a passive-active type 10 transmitter. At the output of the transmitter 10 form the signal currents:

,
Where
I _m is the amplitude value of the signal currents;
ω ₁ = 2πf ₁ - upper frequency;
ω ₂ = 2πf ₂ - lower frequency,
while the following conditions are met:
f ₁ - f ₂ = 2F,
Where
F is the frequency of industrial voltage.

Signal currents (1) flow along the circuit:
"ground" - transmitter output 10 - phase A 0.38 kV - transformer winding 5 - "ground".

,
где
U_m1 и U_m2 - амплитудные значения напряжений сигналов;
φ₁ и φ₂ - начальные фазы.These currents are transformed through a transformer 5 into a medium voltage line 4 and create linear voltage signals in it. The voltage of the signals on the KP 17 is removed from the shunt element 29 of the current transformer 28. Let the output voltages at the outputs of the first 19 and second 20 filters:

,
Where
U _m1 and U _m2 are the amplitude values of the signal voltages;
φ ₁ and φ ₂ are the initial phases.

,
где
K₁ - коэффициент передачи первого балансного фазового детектора 23.The voltage at the output of the first balanced phase detector 23 is equal to:

,
Where
K ₁ - gain of the first balanced phase detector 23.

С учетом (2) и (4) выражение (3) примет вид:
U_вых.23= U_m23cosΩt (5) ,
где

- амплитудное значение напряжения сигнала на выходе первого балансного фазового детектора 23.When the transmitter 10 passive-active type fulfill the conditions:

Taking into account (2) and (4), expression (3) will take the form:
U out. ₂₃ = U _m23 cosΩt (5),
Where

- the amplitude value of the voltage signal at the output of the first balanced phase detector 23.

Ω = 2π (2F)
The local oscillator 25 converts the voltage of the industrial frequency F to a voltage of frequency 2F.

The voltage at the output of the local oscillator 25 is equal to:
U out. ₂₅ = U _mg cos (Ωt + φ _g ) (6),
where U _mr is the amplitude value of the voltage of the local oscillator 25,
φ _g is the initial phase.

Using the phase shifter 26 fulfill the condition φ _g = 0, then the voltage at the output of the phase shifter 26 will be equal to:
U out. ₂₆ = U _mg cosΩt (7).

 We believe that the transfer coefficient of the phase shifter 26 is 1.

(8)
где
K₂ - коэффициент передачи второго фазового детектора 22.Comparing expressions (5) and (7), we see that the frequency and phase of the voltages supplied to the inputs of the second balanced phase detector 24 are equal. The output voltage of the second balanced phase detector 24 (3) is equal to:

(eight)
Where
K ₂ is the transfer coefficient of the second phase detector 22.

 At the output of the second balanced phase detector 24, we have a constant signal voltage, which is supplied to the unit TU, TS, TI 21 for further processing. In the claimed system, synchronous reception of signals is carried out, which corresponds to its optimal processing. The system when transmitting signals from KP 17 to DP 1 is similar to that discussed above.

 The claimed system solves the technical problem of eliminating the shortcomings of the system as. 1737481.

 The system loses performance when there are capacitor banks, which serve to increase the power factor cosφ. . This is due to the fact that the currents of the transmitter signals are introduced and received between the phases of 0.38 kV and they do not reach the windings of transformers 5 and 18, because they are shunted by the capacitance of capacitor banks 6 and 27.

 In the claimed system, this drawback is eliminated, because the signal currents of the transmitters 10 and 22 are introduced between phase A and ground, and received from the shunt elements 16 and 29 of the current transformers 15 and 28, which are installed on the inputs of phase A of the transformers 5 and 18, so the capacitance of the capacitor banks do not shunt them, t. to. capacitors are not directly connected to the ground bus.

 Large dynamic range of voltage variation of the signals at the output of the receiving devices, which does not allow you to choose the optimal threshold in the receiver. This is due to the fact that during the day the loads of 0.38 kV of transformers 5 and 18 vary over a wide range.

In the claimed system, this drawback is eliminated, because select the set value of the local oscillator voltage. So, with
U _mr << U _m23
expression (8) will take the form:
U out. ₂₄ = 2K ₂ U _mr .

 From (9) it follows that the signal voltage at the output of the second balanced phase detector 24 always remains constant and does not depend on changes in the amplitudes of the signal voltages at the inputs of the receivers 19, 20, and 7.8 in a large dynamic range.

Claims (1)

 A system for transmitting and receiving signals through wires of a three-phase power line, containing at the control room a transformer, first and second filters, a transmitter and a telecontrol unit, a telealarm and telemetry, and at a controlled point, a transformer, first and second filters and a tele-control and telemetry control unit, characterized the fact that at the control room a current transformer, a shunt element, first and second balanced phase detectors, a local oscillator, a phase shifter and a capacitor battery are introduced, moreover, the primary winding of the current transformer is connected in series to phase A 0.38 kV, which, together with phases B and C, is connected through the transformer to a three-phase power line, the first terminal of the secondary winding of the current transformer is connected to the first terminal of the shunt element and the first inputs of the first and second filters, the outputs of which are connected respectively to the first and second inputs of the first balanced phase detector, the output of which is connected to the first input of the second balanced phase detector, the output of which is through the unit remote control, tele-alarm and telemetry is connected to the input of the transmitter, the first output of which is connected to phase A 0.38 kV, the second output is connected to the ground bus, the first input of the local oscillator is connected to phase A 0.38 kV, and the second input to earth "bus, the local oscillator output is connected through a phase shifter to the second input of the second balanced phase detector, the capacitor bank consists of three identical capacitors connected in a triangle, the vertices of which are connected to the phases A, B, C of 0.38 sq transformer windings, the second output of the secondary the coils of the current transformer are connected to the second output of the shunt element, the ground bus and the second inputs of the first and second filters, and at the controlled point a current transformer, a shunt element, the first and second balanced phase detectors, a local oscillator, a phase shifter and a capacitor battery, the primary winding of the transformer are introduced current is connected in series to phase A 0.38 kV, which, together with phases B and C, is connected through a transformer to a three-phase power line, the first terminal of the secondary winding of the current transformer is connected with the first output of the shunt element and the first inputs of the first and second filters, the outputs of which are connected respectively to the first and second inputs of the first balanced phase detector, the output of which is connected to the first input of the second balanced phase detector, the output of which is connected to the transmitter input through the telecontrol unit the first output of which is connected to phase A 0.38 kV, and the second to the ground bus, the first input of the local oscillator is connected to phase A 0.38 kV, and the second input to the ground bus, the output of the local oscillator through a phase shifter with the second input of the second balanced phase detector, the capacitor bank consists of three identical capacitors connected in a triangle, the vertices of which are connected to phases A, B and C of 0.38 sq transformer windings, the second terminal of the secondary current transformer is connected to the second terminal a shunt element, an earthing bus and second inputs of the first and second filters.