RU2156543C1 - Method for receiving and transmitting signals in three-phase power supply network - Google Patents

Abstract

FIELD: electrical engineering, communication equipment. SUBSTANCE: method involves synchronous detection of signals using integration, which start and end is defined by characteristic points, which are uniform moments, when total power supply voltage crosses zero level in one phase of network in transmission and reception nodes. This results in possibility to increase frequency range for signal transmission of 50 and 100 baud rate. EFFECT: increased frequency range, increased stability to noise. 1 dwg

Description

 The invention relates to the field of electrical engineering and can find application in organizing communication channels using lines / 0.38 - 10 - 35 - 110 / kV without processing them with high-frequency chokes. A new technical result is the expansion of the frequency range from 1000 Hz to 3000 Hz at a signal transmission rate of 50 and 100 Baud, as well as increasing the noise immunity of signal reception.

 In the proposed method, synchronous signal detection using integration is used, the beginning and end of which are determined by characteristic points, which are the single moments of the transition through zero of the total supply voltage U (t) at the points of transmission and reception. At the same time, the quartz frequency of the signal voltage is used as the heterodyne voltage.

 Closest to the claimed method is a method of transmitting and receiving signals in a three-phase electric network, which is implemented in the patent for the invention N 2121759 cells, 6 H 04 3/54, Bull. N 31 10.11.96, adopted as a prototype.

на

в заявленном способе позволит улучшить отношение сигнал/помеха. Так, в прототипе при скорости передачи сигналов 100 Бод, где

и при максимальной частоте запуска передатчика f₀ ≈ f₂ = 1000 Гц неравенство будет иметь вид:

или 0,01 >> 0,001, т.е. левая часть неравенства будет больше в 10 раз. Это значит, что за период интегрирования Т уложится 10 периодов напряжения частоты сигнала /помехи/.In the known method, the local oscillator voltage is formed from the harmonics of the frequency of the supply voltage F. Due to the fact that the frequency F # 50 Hz in emergency modes, the harmonics of the frequency F change their position on the frequency axis and filter out the local oscillator frequency in a fixed frequency band at high harmonic indices frequency f is complicated. Therefore, as practice has shown, it is necessary to be limited from above to the 20th harmonic (1000 Hz), which narrows the frequency range. The claimed method solves the problem of increasing the frequency range up to 3 kHz, since the frequency of the local oscillator uses the quartz frequency of the signal. Strengthening inequality in prototype c

on the

in the claimed method will improve the signal-to-noise ratio. So, in the prototype at a signal transmission rate of 100 Baud, where

and at the maximum transmitter start frequency f ₀ ≈ f ₂ = 1000 Hz, the inequality will be:

or 0.01 >> 0.001, i.e. the left side of the inequality will be 10 times more. This means that during the integration period T, 10 periods of voltage of the signal frequency / interference / will be stacked.

.In the claimed method, for example, with n = 3 and f ₀ = 1000 Hz, the inequality takes the form:

.

или

т. е. левая часть неравенства будет больше в 160 раз. Это значит, что за период интегрирования Т уложится 160 периодов напряжения частоты сигнала /помехи/. Известно, что математическое ожидание М амплитуды помехи U_n(t), которая флуктуирует около нуля, описывают выражением: M[U_n](t) ---> 0 при знаменателе в правой части неравенства _→ ∞. Таким образом, чем лучше выполняют неравенство, тем выше будет отношение сигнал/помеха после обработки сигнала в интеграторе. При увеличении частотного диапазона до 3 кГц неравенство еще "усилят" в три раза.Given the fact that
f _Σ = f ₁ + f ₂ = 2f ₀ ,
the inequality will take the form:

or

i.e., the left side of the inequality will be 160 times greater. This means that during the integration period T, 160 periods of voltage frequency of the signal / interference / will be laid out. It is known that the mathematical expectation M of the interference amplitude U _n (t), which fluctuates around zero, is described by the expression: M [U _n ] (t) ---> 0 with the denominator on the right-hand side of the inequality _ → ∞. Thus, the better the inequality is fulfilled, the higher the signal-to-noise ratio after processing the signal in the integrator. With an increase in the frequency range up to 3 kHz, the inequality is still “amplified” three times.

обратной последовательности на частоте f₁ и ток сигнала

прямой последовательности на частоте f₂, где f₂-f₁=2F, передают эти токи по трехфазной электрической сети в пункт приема, преобразуют

в напряжения

преобразуют эти напряжения путем фильтрации соответственно в напряжения U₁(t) = U_m1cosω₁t и U₂(t) = U_m2cosω₂t где ω₁= 2πf₁,ω₂= 2π-f₂ в узкой полосе пропускания частот, перемножают U₁(t) и U₂(t), выделяют путем фильтрации напряжение суммарной частоты U_Σ(t) = U_mΣcosω_Σt, где ω_Σ= 2πf_Σ,f_Σ= f₁+f₂= 2f₀,
f₀ - частота запуска передатчика, преобразуют напряжение U_Σ(t) в напряжение U_Σn(t) = U_mΣncos2ⁿt путем n - кратного умножения и n - кратной фильтрации, где n = 1,2,3,4, . ,.., умножают U_Σn(t) на U_Σn(t), из полученного напряжения выделяют путем фильтрации постоянную составляющую U_c, интегрируют U_c в интервале Т, где

при скорости передачи сигналов 50 Бод и

при скорости передачи сигналов 100 Бод, выполняют неравенство

, при этом начало и конец интервалов передачи сигналов и интегрирования соответствуют единым моментам времени перехода общего питающего напряжения U(t) через ноль в пунктах передачи и приема.In the claimed method for transmitting and receiving signals in a three-phase electric network, the supply voltage U (t) of industrial frequency F is converted into a signal current at a transmission point

reverse sequence at frequency f ₁ and signal current

direct sequence at a frequency f ₂ , where f ₂ -f ₁ = 2F, transmit these currents through a three-phase electric network to the receiving point, convert

in tension

transform these voltages by filtration, respectively, into the voltages U ₁ (t) = U _m1 cosω ₁ t and U ₂ (t) = U _m2 cosω ₂ t where ω ₁ = 2πf ₁ , ω ₂ = 2π-f ₂ in a narrow frequency band U ₁ (t) and U ₂ (t) are multiplied, the total frequency voltage U _Σ (t) = U _{mΣ cosω Σ} t, where ω _Σ = 2πf _Σ , f _Σ = f ₁ + f ₂ = 2f _{0 is} isolated by filtration ,
f ₀ is the transmitter startup frequency, the voltage U _Σ (t) is converted to voltage U _Σn (t) = U _mΣn cos2 ⁿ t by n - multiple multiplication and n - multiple filtering, where n = 1,2,3,4,. , .., multiply U _Σn (t) by U _Σn (t), extract the constant component U _c from the obtained voltage by filtering, integrate U _c in the interval T, where

at a signal rate of 50 baud and

at a signal transmission rate of 100 Baud, the inequality

, the beginning and the end of the intervals of signal transmission and integration correspond to single points in time of the transition of the total supply voltage U (t) through zero at the points of transmission and reception.

A device (see drawing) that implements the claimed method, contains in the transfer point synchronizer 1 characteristic points / synchronizer /, transmitter 2 passive-active type / transmitter /, three-phase electrical network 3 / network /, voltage filter of symmetrical components / FSS / reverse sequence 4, FSS direct sequence 5, narrow-band filter 6 / UPF / frequency f ₁ , UPF 7 frequency f ₂ , multiplier 8, UPF frequency f _Σ = f ₁ + f ₂ 9, first 10, second 11, .. n-th 12 frequency converter / converter /, multiplier 13, low-pass filter / low-pass filter / 14, integrate p 15, synchronizer 16, phase shifter 17.

мгновенные значения которых описывают выражениями:

где I_m - амплитудное значение токов на частотах ω₁ и ω₂, ω₁= (ω₀-Ω) и ω₂= (ω₀+Ω); ω₀= 2πf₀; Ω = 2πF, f₁=f₀-F, f₂=f_0+F;

f₀ - частота запуска передатчика.The device operates as follows:
The synchronizer 1 generates pulses at the transmission point at single moments of the transition time of the supply voltage U (t) of the frequency F through zero. The beginning and end of signal transmission coincide with the unified moments of the transition time of the supply voltage U (t) of frequency F through zero at the points of transmission and reception. When the transmitter 2 in its phase wires A, B, C form the following signal currents by analogy with the prototype

the instantaneous values of which are described by the expressions:

where I _m is the amplitude value of currents at frequencies ω ₁ and ω ₂ , ω ₁ = (ω ₀ -Ω) and ω ₂ = (ω ₀ + Ω); ω ₀ = 2πf ₀ ; Ω = 2πF, f ₁ = f ₀ -F, f ₂ = f _{0 + F} ;

f ₀ - transmitter start frequency.

, мгновенные значения которых описывают выражениями:

где U_A, U_B, U_C - разные напряжения сигнала.These currents form at the inputs of the FSS 4 and FSS 5 three-phase voltage of the reverse and forward sequences

whose instantaneous values are described by the expressions:

where U _A , U _B , U _C are different signal voltages.

From the expression / 2 / it follows that at a frequency of ω _{1 there} are voltages of reverse phase rotation A, C, B at a frequency of ω ₂ - direct rotation of phases A, B, C. The voltage of the signal of the negative sequence at frequency ω ₁ takes FSS 4. The signal voltage direct sequence at a frequency of ω ₂ takes FSS 5. The expression of the instantaneous values of the signal voltages at the respective outputs of the FSS 4 and FSS 5 are:
U ₄ (t) = U _m4 cosω ₁ t (3)
U ₅ (t) = U _{m5 cosω 2} t (4)
Due to the fact that the voltage of the quartz frequency signal is used as the local oscillator voltage, we omit the phase shifts. These voltages are obtained in a wide band of FSS 4 and FSS 5, respectively, they are supplied to UPF 6 and UPF 7. At the output of UPF 6 they have voltage U ₁ (t), and at the output of UPF 7 they have U ₂ (t) according to the description of the claims:
U ₁ (t) = U ₆ (t) = U _m1 cosω ₁ t (5)
U ₂ (t) = U ₇ (t) = U _m2 cosω ₂ t (6)
In the multiplier 8, U ₁ (t) and U ₂ (t) are multiplied, as a result, the voltages of the difference and total frequencies
U ₈ (t) = U _m8 cos (ω ₂ -ω ₁ ) t + U _m8 cos (ω ₂ + ω ₁ ) t (7)
In the prototype, the difference frequency is isolated, in the claimed method, the total frequency is isolated using UPF 9 according to the claims:
U _Σ (t) = U ₉ (t) = U _{mΣ cosω Σ} t (8)
Where
ω _Σ = 2πf _Σn f _Σ = f ₁ + f ₂ = 2f ₀
The voltage U _Σ (t) is supplied to the input of the first converter 10. The converter consists of a multiplier 10 ', which is connected to the output of the UPF 9 by your combined inputs, and the output of the multiplier 10 ^{1 is} connected to the input of the UPF 10 ² , the output of which is the output of the converter 10, which connected to the input of the second Converter 11. Since the operation of the converters is identical, consider the operation of the first, second and nth converters.

Выделяют с помощью узкополосного фильтра 10² напряжение суммарной частоты, которое будет выходным для преобразователя 10 и входным для второго преобразователя 11.At the output of the multiplier 10 ^1, by analogy with / 7 /, there are voltage differential and total frequencies:

Using the narrow-band filter 10 ^{2, the} voltage of the total frequency is extracted, which will be output for the converter 10 and input for the second converter 11.

С помощью ФНЧ 14 выделяют напряжения разностной частоты, т.е. напряжение постоянной составляющей U_c согласно формуле изобретения:
U_c=U_m13 • cos 0^o=U_m13 (14)
U_c будет являться амплитудой /огибающей/ сигнала. U_c подают на первый вход интегратора 15, на второй вход которого подают импульсы синхронизатора 16 через фазовращатель 17, с помощью которого совмещают единые моменты времени начала и конца интервала интегрирования Т с началом и концом передачи сигнала. Выход интегратора 15 является информационным.U ₁₀ (t) = U _m10 cos2ω _Σ t (10)
By analogy with / 10 / the voltage at the output of the second Converter 11 will be equal to:
U ₁₁ (t) = U _m11 cos4ω _Σ t (11)
The voltage at the output of the nth converter will be equal to:
U _Σn (t) = U ₁₂ (t) = U _mΣn cos2 ⁿ • ω _Σ t (12)
Thus, each subsequent converter gives a voltage with a double frequency. By n-fold multiplication and n-fold filtering, we obtain the desired frequency value 2 ⁿ ω _Σ . The voltage U _Σn (t) from the output of the nth converter 12 is supplied to a multiplier 13 having combined inputs. From the output of the multiplier 13 have voltages with difference and total frequencies:

Using the low-pass filter 14, the difference frequency voltages are isolated, i.e. DC voltage U _c according to the claims:
U _c = U _m13 • cos 0 ^o = U _m13 (14)
U _c will be the amplitude / envelope / signal. U _{c is} fed to the first input of the integrator 15, to the second input of which pulses of the synchronizer 16 are fed through the phase shifter 17, with the help of which the single moments of the start and end of the integration interval T are combined with the beginning and end of the signal transmission. The output of the integrator 15 is informational.

Thus, we have proved that in the claimed method:
1. The operating frequency range in the tonal range is increased from 1 kHz to 3 kHz and the choice of the transmitter start frequency f ₀ does not depend on the instability of the frequency F of the supply voltage U (t).

, где n выбирают в зависимости от технических требований получения заданного отношения сигнал/помеха на информационном выходе интегратора 15.2. The noise immunity in the claimed method is increased due to the implementation of more severe inequality

, where n is selected depending on the technical requirements for obtaining a given signal / noise ratio at the information output of the integrator 15.

Claims (1)

A method of transmitting and receiving signals in a three-phase electric network, according to which the supply voltage U (t) of industrial frequency F is converted into a signal current at a transmission point

reverse sequence at frequency f ₁ and signal current

direct sequence at a frequency f ₂ , where f ₂ - f ₁ = 2F, these currents are transmitted through a three-phase electric network to the receiving point, convert

in tension

transform these voltages by filtration, respectively, into the voltages U ₁ (t) = Um ₁ COSω ₁ t and U ₂ (t) = Um ₂ COSω ₂ t where ω ₁ = 2πf ₁ , ω ₂ = 2πf ₂ in a narrow passband, multiply U ₁ (t) and U ₂ (t), while the beginning and end of the signal transmission and integration intervals T correspond to the common transition times of the common supply voltage U (t) of frequency F at the points of transmission and reception through zero, characterized in that from the product U ₁ (t) to U ₂ (t), the total frequency voltage UΣ (t) = Um _Σ COSω _Σ t, where f _Σ = f ₁ + f ₂ = 2f ₀ , f ₀ is the transmitter start frequency, is isolated by filtering convert voltage U _Σ (t) to voltage U _Σn (t) by n = 1,2,3, ..., sequential operations, each of which includes the action of multiplication, followed by isolation by filtering the voltage of double frequency, multiply U _Σn (t ) on the U _Σn (t), from the resulting voltage is isolated by filtration DC component U _c, U _c is integrated in the interval t, where

at a signal rate of 50 baud and

at a signal transmission rate of 100 Baud, the inequality