RU2144730C1 - Device for transmission and reception of signals in three-phase mains network - Google Patents

Abstract

FIELD: electrical engineering, in particular, communication channels using 0.38-10-35- 110 kV transmission lines without high-frequency filters. SUBSTANCE: device uses synchronous signal detection using integration, which start and end are determined by characteristic points, which are defined as moments of zero transition of total power supply voltage in stations for reception and transmission. EFFECT: increased stability to noise, increased speed of signal transmission up to 50-100 bits per second. 1 dwg

Description

 The invention relates to the field of electrical engineering and can find application in organizing communication channels using a three-phase electric network / 0.38-10-35-110 / kV without its processing by high-frequency chokes, while the transmission and reception of signals is carried out on the side of 0.38 kV.

 A known device for transmitting and receiving signals in a three-phase electrical network - and.with. USSR N 1819025 class. 6 G 08 G 19/12, 1988. The disadvantages of the known device is the low noise immunity when receiving signals and low, no more than 10 Baud signal transmission rate.

 Closest to the claimed system is a device for transmitting and receiving signals over wires of a three-phase power line, patent for invention No. 2061256, class. 6 G 08 G 19/12, 1996 / prototype /. This device has the same disadvantages.

 The claimed system solves the problem of increasing the noise immunity of signal reception when a new technical result is achieved - increasing the signal transmission rate to 50 or 100 Baud.

 A system for transmitting and receiving signals in a three-phase electric network, FIG. 1, contains at the transmission point the first synchronizer 1, the transmitter 2, the electric network 3, at the reception point the three-phase rectifier bridge 4, the resistor 5, the capacitor 6, the first transformer 7, the first narrow-band filter / UPF / 8, the first multiplier 9, the second UPF 10 , second transformer 11, first phase shifter / FV / 12, converter 13, third UPF 14, second PV 15, second synchronizer 16, second multiplier 17, fourth UPF 18, third multiplier 19, low-pass filter / low-pass filter / 20, integrator 21, while the phase wires ABC of the electrical network 3 are connected to the inputs of the bridge 4, the output of which is connected to a resistor 5 and a series circuit consisting of a capacitor 6 and a primary winding of the first transformer 7, the secondary winding of which is connected to the input of the first UPF 8, the output of which is connected to the first input of the first multiplier 9, the output of which is connected to the input of the second UPF 10, the output of which is connected to the first input of the third multiplier 19, the output of which is connected to the first input of the integrator 21, the primary winding of the second transformer 11 is connected respectively to phase A - "Earth", the secondary winding of which responsibly connected to the inputs of the first 12 and second 15 PV, the output of which is connected to the input of the second synchronizer 16, the output of which is connected to the second input of the integrator 21, the output of the first PV 12 is connected to the input of the converter 13, the output of which is connected to the third UPF 14, the output of which, respectively connected to the second input of the first multiplier 9 and the first, second inputs of the second multiplier 17, the output of which is connected to the output of the fourth UPF 18, the output of which is connected to the second input of the third multiplier 19, the inputs of the first synchronizer 1 under are connected respectively to phase A and Earth, the output of which is connected to the input of transmitter 2, the outputs of which are connected to the phase wires of the network A, B, C.

 The increase of noise immunity when receiving signals in the inventive system is carried out through the use of synchronous detection with the subsequent integration of unipolar voltage, while it is possible to receive signals with a signal / noise ratio of less than unity. This is because in the claimed system there is no suppression of a weak signal by a stronger signal / interference /. Therefore, the quality of the communication channel of the system is practically independent of the signal-to-noise ratio / A.P. Manovtsev. Introduction to digital radio telemetry. Energy. M.S. 242 /.

 Achieving the technical result - increasing the transmission speed to 50 or 100 Baud is carried out due to the availability of information at the receiving point about the beginning and end of signal transmission, which allows you to correctly select the beginning and end of the integration interval O≤t≤T at characteristic points corresponding to common points in transition time and supply voltage through zero at the points of transmission and reception.

The system works as follows:
The synchronizer 1 generates pulses at the point of transmission at the moments of the transition of the supply voltage U (t) / for a particular case, phase A - "Earth" / through zero. Pulses follow with a period of T = 0.01 s at a signal transmission rate of 100 Baud and T = 0.02 s - 50 Baud.

Примечание:
Если раскрыть /1/, то следует, что в сеть вводят, как и у прототипа, ток сигнала обратной последовательности

(f₁) на частоте f₁, и ток прямой последовательности

(f₂) на частоте f₂, где индексы 1, 2 соответственно определяют ток прямой и обратной последовательностей
f₁=f₀-F; f₂=f₀+F;

ω₁= (ω₀-Ω); ω₂= (ω₀+Ω).
n>>1 - натуральное число,
2I_m - амплитуда тока биения колебаний.The beginning and end of signal transmission coincide with the moments when the supply voltage passes through zero. When the transmitter is passive-active type 2 in its phase wires A, B, C form the following signal currents

Note:
If you open / 1 /, then it follows that the network is injected, like the prototype, the signal current of the negative sequence

(f ₁ ) at a frequency f ₁ , and the direct sequence current

(f ₂ ) at a frequency f ₂ , where indices 1, 2 respectively determine the current of the forward and reverse sequences
f ₁ = f ₀ -F; f ₂ = f ₀ + F;

ω ₁ = (ω ₀ -Ω); ω ₂ = (ω ₀ + Ω).
n >> 1 is a natural number,
2I _m is the amplitude of the beat current.

 Due to the fact that the signal processing at the reception point is carried out in a different way than in the method adopted for the prototype, a more convenient form for analyzing the implementation of the claimed method is to record the signal currents, according to / 1 /.

где I_m=0,5 амплитуды токов биения колебаний согласно /1/ /Л.А. Бессонов Теоретические основы электротехники. - М. Энергия 1978 г. 305 с./.The currents / 1 / are transmitted through the network 3 to the receiving point, which are fed to the inputs of the three-phase rectifier bridge 4. The currents in the secondary winding of the transformer 7 - i ₇ (t), which serves for galvanic isolation from the mains voltage U (t) and taking into account that the diodes of the bridge 4 open the supply voltage of the network U (t), frequency F, have the form

where I _m = 0.5 the amplitude of the currents of the beat of oscillations according to / 1 / / L.A. Bessonov Theoretical Foundations of Electrical Engineering. - M. Energia 1978 305 pp. /.

В дальнейшем токи с комбинационными частотами

и т. д. будут отфильтрованы фильтром частоты ω₀-8. Элементы трехфазного выпрямительного моста 4 выполняют следующие функции: через резистор 5 протекает постоянная составляющая выпрямленного тока частоты F. Конденсатор 6 и индуктивности обмоток трансформатора 7 образуют последовательный L, C контур, который настраивают в резонанс на частоту ω₀. Напряжение сигнала U₀(t) на выходе фильтра частоты ω₀-8 с учетом /3/ и значений коэффициентов передачи элементов устройства равно:

Напряжение сигнала /4/ подают на первый вход умножителя 9. Элементы системы /фиг. 1/ 3 - 8 образуют приемный тракт сигнала.For the claimed method, only current with a signal frequency ω ₀ is of interest, i.e. according to / 2 / the signal current is:

Further currents with combination frequencies

etc. will be filtered by a frequency filter ω ₀ -8. The elements of the three-phase rectifier bridge 4 perform the following functions: a constant component of the rectified current of frequency F flows through the resistor 5. The capacitor 6 and the inductance of the transformer windings 7 form a series L, C circuit, which is tuned to the frequency ω ₀ in resonance. The signal voltage U ₀ (t) at the output of the frequency filter ω ₀ -8, taking into account / 3 / and the values of the transmission coefficients of the elements of the device is equal to:

The signal voltage / 4 / is fed to the first input of the multiplier 9. Elements of the system / Fig. 1/3 - 8 form the receiving signal path.

Напряжение /5/ подают через ФВ - 12 на вход преобразователя 13, с выхода которого / для частного случая, когда n является нечетным числом/, образуют напряжение типа "меандр", которое можно математически выразить в координатах: ось Y - U₁₃(t); ось X - t.Consider the path of generating the local oscillator voltage U _r (t) at the receiving point. Mains voltage / for a special case, Phase A - ground / is supplied to step-down transformer 11. From its secondary winding the voltage is obtained:

The voltage / 5 / is fed through PV-12 to the input of the converter 13, from the output of which / for the particular case when n is an odd number /, a meander voltage is formed, which can be mathematically expressed in the coordinates: axis Y - U ₁₃ (t ); X axis - t.

где: T_F=0,02 с - период частоты F.

where: T _F = 0.02 s - period of frequency F.

Таким образом, напряжение /7/ имеет напряжение постоянной составляющей и набор напряжений с нечетными гармониками частоты Ω-3Ω,5Ω...nΩ. Фильтром частоты ω₀-14 выделяют напряжение с заданной нечетной гармоникой n частоты Ω, т.е. ω₀= n•Ω.
На выходе фильтра частоты ω₀-14 имеют напряжение гетеродина

Фазовые набеги в устройстве устраняют ФВ - 12. Напряжение первого гетеродина /8/ подают на второй вход умножителя 9. Известно, что при подаче на входы умножителя двух напряжений с одинаковыми частотами

и фазами

на его выходе имеют напряжение

где K₁ и K₂ - коэффициенты преобразования умножителя 9.Having expanded in a Fourier series / 6 /, they have:

Thus, the voltage / 7 / has a DC voltage and a set of voltages with odd frequency harmonics Ω-3Ω, 5Ω ... nΩ. With a frequency filter ω ₀ -14, a voltage with a given odd harmonic n of frequency Ω is isolated, i.e. ω ₀ = n • Ω.
The output of the frequency filter ω ₀ -14 have a local oscillator voltage

Phase raids in the device eliminate PV - 12. The voltage of the first local oscillator / 8 / is fed to the second input of the multiplier 9. It is known that when two voltages with the same frequencies are applied to the inputs of the multiplier

and phases

they have voltage at its output

where K ₁ and K ₂ are the conversion factors of the multiplier 9.

амплитудное значение.

amplitude value.

It should be noted that the choice of the value n >> 1 has a limitation that determines the length of the three-phase electric network - L. In order to prevent wave processes from occurring in the line (in this case, it is necessary to install barriers /, the condition should be fulfilled:
L> λ / 4, (10)
where λ is the wavelength.

To transmit signals on 10/35/110 kV lines, the following frequency range is usually accepted:
500 Hz≤f ₀ ≤2000 Hz, (11)
with 10≤n≤40.

On the other hand, for optimal signal processing using integration, it is necessary to fulfill the condition:
T >> 1 / f ₀ , (12)
i.e., the higher the processing frequency, the higher the signal processing quality. Condition / 12 / is not feasible for small values of n. So, at a signal transmission rate of 100 Baud, i.e. T = 0.01 s and f ₀ = 500 Hz / n = 10 / inequality / 12 / will not be satisfied. We take the signal processing frequency 2f ₀ (α = 2). Moreover, the inequality / 12 / will be of the form:
0.01 >> 0.001 (13)
which is quite acceptable.

Это напряжение подают на первый вход умножителя 19.The second term of the expression / 9 / has a frequency of 2ω ₀ . Using UPF 10 emit voltage U ₂ (t) of this frequency:

This voltage is applied to the first input of the multiplier 19.

подают также на два входа умножителя 17.Voltage

also served on two inputs of the multiplier 17.

где K₃ и K₄ - коэффициенты преобразования умножителя 17.At its output, by analogy with / 9 /, they have the voltage:

where K ₃ and K ₄ are the conversion factors of the multiplier 17.

Это напряжение подают на второй вход умножителя 19. Напряжение на его выходе имеет вид:

где K₅ и K₆ - коэффициенты преобразования умножителя 19.Using UPF 18 isolate the voltage of the second local oscillator with a frequency of 2ω ₀ .

This voltage is supplied to the second input of the multiplier 19. The voltage at its output has the form:

where K ₅ and K ₆ are the conversion factors of the multiplier 19.

Это напряжение подают на первый вход интегратора 21. На его второй вход подают импульсы синхронизатора 16, причем с помощью ФВ 15 получают одновременное следование этих импульсов с импульсами синхронизатора 1. Частоту ω₀ для запуска передатчика пассивно-активного типа 2 формируют из частоты Ω = 2πF аналогично с формированием частоты ω₀= nΩ в тракте первого гетеродина.Using a low-pass filter 20 emit a DC voltage

This voltage is supplied to the first input of the integrator 21. At its second input, the pulses of the synchronizer 16 are supplied, and with the help of PV 15, these pulses are simultaneously followed by the pulses of the synchronizer 1. The frequency ω ₀ for starting the passive-active type 2 transmitter is formed from the frequency Ω = 2πF similarly with the formation of the frequency ω ₀ = nΩ in the path of the first local oscillator.

The increase of noise immunity when receiving signals is provided as follows:
1. The voltage U _n at the input of the integrator 21 is unipolar in the integration time interval O≤t≤T.

2. The interference voltage U _interference (t) on the integration time interval O≤t≤T has a variable / fluctuating around zero / component with the expected value:
M [U _interference (t)] = O.

3. The condition T >> 1 / 2f _{0 is} fulfilled.

 The ability to receive signals with a signal to noise ratio is less than in the prototype, proves the achievement of the goal - increasing the noise immunity of signal reception.

 A new technical result was obtained - the signal transmission rate was increased to 50 or 100 Baud.

Claims (1)

A system for transmitting and receiving signals in a three-phase electric network, comprising a transmitter connected to the receiving point through phase wires A, B, C of the electric network to the receiving point, a first narrow-band filter (UPF), first and second phase shifters (PV), characterized in that the first synchronizer was introduced at the transfer point, a three-phase rectifier bridge, a resistor, a capacitor, first and second transformers, a second, third and fourth UPF, a first, second and third multipliers, a converter, a second synchronizer, a lower filter their frequencies, an integrator, while the phase wires A, B, C of the electrical network are connected to the inputs of the bridge, the output of which is connected to a resistor and a series circuit consisting of a capacitor and a primary winding of the first transformer, the secondary winding of which is connected to the input of the first UPF, the output of which connected to the first input of the first multiplier, the output of which is connected to the input of the second UPF, the output of which is connected to the first input of the third multiplier, the output of which is connected to a low-pass filter, the output of which is connected to the first input the integrator, the primary winding of the second transformer is connected respectively to phase A - Earth, the secondary winding is respectively connected to the inputs of the first and second PV, the output of which is connected to the input of the second synchronizer, the output of which is connected to the second input of the integrator, the output of the first PV is connected to the input a converter whose output is connected to a third UPF whose output is respectively connected
with the second input of the first multiplier and the first and second inputs of the second multiplier, the output of which is connected to the input of the fourth UPF, the output of which is connected to the second input of the third multiplier, the inputs of the first synchronizer are connected respectively to phase A and Earth, the output of which is connected to the input of the transmitter.