RU2224364C2 - Generator using passive-active method for signal current input in three-phase power mains - Google Patents

Abstract

FIELD: electrical engineering; organizing communication channels in three-phase mains. SUBSTANCE: generator designed for organizing communication channels using three-phase, 0.4 to 35 kV power mains without introducing wave traps in them is provided with newly introduced low-voltage winding of 10/0.4 kV transformer phase C, second inductance coil, and second capacitor, all being respectively connected to generator circuit. In this way circuit for first-capacitor discharge through resistor is eliminated, power loss is reduced by 160 W, transistor can be used as switch for inputting current in power mains. EFFECT: reduced power requirement of generator. 1 cl, 2 dwg

Description

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

 It is known "Device for transmitting signals over a three-phase power line" (Patent SU 1107750 A, H 04 B 3/54, 1982). A disadvantage of the known device is the absence of a limiting resistance in the signal key circuit (key), which should limit the current through the key when it is closed, if for some reason it was not turned off at the specified time, and the device will burn out before the fuses fail .

 There is also a generator with a passive-active method of inputting signal currents into a three-phase electric network, which is adopted as a prototype (generator) (S. A. Tsagareishvili, K. I. Gutin. Theoretical basis for constructing a channel-forming device at tonal frequencies over electric networks 0.4 -35 kV Science and technology in industry, Moscow, 2 (5), 2001, p. 55-56).

 In the known generator, a limiting resistor is installed, but there is a drawback - high power consumption from the network. The implementation of the claimed generator significantly reduces power consumption from the network.

A generator with a passive-active method of inputting signal currents into a three-phase electric network 2, containing a transformer 10 / 0.4 kV 1 (transformer), the low-voltage winding of which Phase A is connected to the first terminal of the first inductor 3, the second terminal of which is connected to the first lining of the first capacitor 4 and to the cathode and anode of the fourth 5 ₄ and first 5 ₁ diodes, respectively, the cathodes of the first 5 ₁ and second 5 ₂ diodes are connected to the first output of the resistor 6, the second output of which is connected to the input of the signal switch 7, the output of which is connected n, respectively, to the anodes of the fourth 5 ₄ and third 5 ₃ diodes, the third phase of the transformer is introduced into it, the second inductor 8, which is inductively connected to the first inductor 3, the second capacitor 9, while the second lining of the first capacitor 4 is connected to the first output of the first inductors 3, the anode and cathode of the second 5 ₂ and third 5 ₃ diodes, respectively, are connected to the "ground" bus, ("ground") of the transformer, the low-voltage winding of the transformer Phase B is connected to the first output of the second inductor 8, in the second terminal of which is connected to the first plate of the second capacitor 9, the second plate of which is connected to the low voltage winding of the transformer 1 Phase C.

The generator circuit with a passive-active method of inputting signal currents into a three-phase electric network (generator) is shown in figure 1, where:
1. Transformer;
2. Network;
3. The first coil;
4. The first capacitor;
5. The diode bridge. 5 ₁ , 5 ₂ , 5 ₃ , 5 _4, respectively, its first, second, third, fourth diodes;
6. Resistor;
7. The key;
8. The second coil;
9. The second capacitor.

 The generator operates as follows.

, через ключ протекают два тока:
1. Ток заряда i(t) электромагнитной энергией первой катушки;
2. Ток разряда конденсатора 4₁ на резистор 6. (Значениями сопротивлений диодов и ключа пренебрегают в связи с их малостью по сравнению с величиной сопротивления резистора 6). Ток разряда протекает по цепи: "плюс" конденсатора 4₁ - первый диод 5₁ - резистор 6 - ключ 7 - третий диод 5₃ - "минус" конденсатора 4₁. Действующее значение напряжения, приложенного к конденсатору 4₁, равно U=380 В. Энергия, накопленная конденсатором 4₁ за один период Т_о, равна:

где Wc - энергия электрического поля, накопленная конденсатором 4₁ за период T_о;
С - емкость конденсатора 4₁.1. Consider the operation of the generator, made according to the scheme, as in the prototype. For this, elements 4, 8, 9, the cathode of the third 5 ₃ and the anode of the second 5 ₂ diodes are not connected to the ground, but to Phase B. The connection is shown by a dotted line. The capacitor of the prototype 4 ₁ (figure 1) is shown by a dotted line, included between Phases AB. We assume that the potential of Phase A is higher than the potential of Phase B. At t = 0, the capacitor 4 ₁ is charged, as shown in Fig. 1. In time lapse

, two currents flow through the key:
1. The charge current i (t) is the electromagnetic energy of the first coil;
2. The discharge current of the capacitor 4 ₁ to the resistor 6. (The resistance values of the diodes and the key are neglected due to their smallness compared to the resistance value of the resistor 6). The discharge current flows along the circuit: “plus” of the capacitor 4 ₁ - first diode 5 ₁ - resistor 6 - key 7 - third diode 5 ₃ - “minus” of the capacitor 4 ₁ . The effective value of the voltage applied to the capacitor 4 ₁ is U = 380 V. The energy stored by the capacitor 4 ₁ for one period T _o is:

where Wc is the energy of the electric field accumulated by the capacitor 4 ₁ for the period T _o ;
C is the capacitance of the capacitor 4 ₁ .

где U_m = 536 В - амплитудное значение;
t - время разряда конденсатора;
l - основание натурального логарифма;
R - сопротивление резистора 6;
τ=R•C.When the current flow of the discharge of the capacitor 4 ₁ , the voltage U _c (t) decreases exponentially:

where U _m = 536 V is the amplitude value;
t is the discharge time of the capacitor;
l is the base of the natural logarithm;
R is the resistance of the resistor 6;
τ = R • C.

Переходный процесс считают законченным через промежуток времени
t≅(3÷4)τ
Для расчета величины мощности потерь в прототипе задают конкретные исходные данные, взятые, например, из расчета генератора, схема которого аналогична схеме аналога (К.И.Гутин, С.А.Цагарейшвили. Генератор гармонических колебаний для передачи информации в сельских электрических сетях. Научно-технический бюллетень по электрификации сельского хозяйства. Выпуск 1 (53). ВИЭСХ, М., 1985 г., с.6-16).The energy dissipated in the resistance R during the entire transient process is equal to the energy stored in the electric field before switching, i.e. in the time interval t, where

Transition considered complete after a period of time
t≅ (3 ÷ 4) τ
To calculate the power losses in the prototype, specific initial data is taken, for example, taken from the calculation of a generator whose circuit is similar to that of an analogue (K.I. Gutin, S.A. Tsagareishvili. Harmonic oscillation generator for transmitting information in rural electric networks. Scientific -technical bulletin on the electrification of agriculture. Issue 1 (53). VIESH, M., 1985, p.6-16).

Where f _o = 833 Hz is the signal current frequency;
R = 8 Ohm - resistance of the resistor 6;
C = 8 • 10 ^-6 F - capacitor 4 ₁ ;
L = 4.57 • 10 ^-3 H - inductance of the first coil.

Определим промежуток времени t_pаз (4τ) разряда конденсатора 4₁ за промежуток времени 4τ:
4τ=4RC=4•8•8•10^-6=2,56•10^-4 c (7)
Сравнивая выражения (6) и (7), можно считать, что конденсатор 4₁ полностью разрядился на резистор 6.Determine the time t _paz (C) adopted for the discharge of the capacitor 4 ₁

Define the period of time t _paz (4τ) discharging the capacitor April ₁ during a time interval 4τ:
4τ = 4RC = 4 • 8 • 8 • 10 ^-6 = 2.56 • 10 ^-4 s (7)
Comparing expressions (6) and (7), we can assume that the capacitor 4 _{1 is} completely discharged to the resistor 6.

Следует учесть, что основная нагрузка по передаче сигналов приходится на генератор, установленный на диспетчерском пункте (ДП), который ведет циклический опрос состояния электрооборудования, установленного на 1, 2, 3.... контролируемых пунктах (КП). Принимают условия, что длительность передачи информации с КП в два раза больше, чем длительность запроса КП с ДП, тогда с учетом (9) мощность потерь в генераторе ДП - Р_п(ДП) будет равна:

2. Рассмотрим работу генератора, реализующего заявленное изобретение.Determine the power loss P _p due to the discharge of the capacitor 4 ₁ to the resistor 6 during continuous operation of the generator
P _p = U ² Cf ₀ = 380 ² • 8 • 10 ^-6 • 833 = 960 W (8)
Given that the generator works only when the transmission symbols "1", a transmission symbol "0" is not working, and that the communication of signals "1" and "0" is assumed equal, the power loss to a character "1" - P _n ( "1") is equal to:

It should be noted that the main load for signal transmission falls on the generator installed at the control room (DP), which conducts a cyclic survey of the status of electrical equipment installed at 1, 2, 3 .... controlled points (KP). Accept the conditions that the duration of the transmission of information from the CP is twice as long as the duration of the request from the CP with DP, then, taking into account (9), the power of losses in the DP - R _p (DP) generator will be equal to:

2. Consider the operation of a generator that implements the claimed invention.

амплитудное значение тока заряда 2I_m согласно (1) равно:

где

;
R=8 Ом;
L₁=4,57•10^-3 Гн;

;
f_o=833 Гц,
т. е. параметры для расчета i₁(t) приняты, как в расчете прототипа по п. 1.Let the potential of Phase A be higher than the potential of "Earth", while the first 5 ₁ and the third 5 ₃ diodes are open. At time

the amplitude value of the charge current 2I _m according to (1) is equal to:

Where

;
R = 8 ohms;
L ₁ = 4.57 • 10 ^-3 H;

;
f _o = 833 Hz,
i.e., the parameters for calculating i ₁ (t) are adopted, as in the calculation of the prototype according to claim 1.

будет равна:

где 2Im=16 А, согласно (11).During the passage of current i (t) through the low-voltage winding of the Phase A transformer - to the first coil 3 - to the first diode 5 ₁ - to the resistor 6 - to the key 7 - to the third diode 5 ₃ - the ground in the first coil 3 will accumulate electromagnetic energy, which at the moment time

will be equal to:

where 2Im = 16 A, according to (11).

ключ 7 размыкают и в параллельном контуре L₁С₁ возникнут свободные колебания тока i(t) при

В связи с тем, что первая 3 и вторая 8 катушки индуктивно связаны, в последовательном контуре L₂С₂ также возникнет ток сигнала i_o(t), значение которого определено в (3).At time

the key 7 is opened and in the parallel circuit L ₁ C ₁ there will be free oscillations of the current i (t) at

Due to the fact that the first 3 and second 8 coils are inductively coupled, a signal current i _o (t) will also occur in the serial circuit L ₂ C ₂ , the value of which is defined in (3).

Выражение (13) показывает, что в две Фазы сети В и С вводят два тока на частотах ω₁ и ω₂, т.е.The waveform of the current i _o (t) is shown in figure 2. Expression (3) can be written in another form

Expression (13) shows that in two phases of the network B and C, two currents are introduced at frequencies ω ₁ and ω ₂ , i.e.

i _o (f ₁ ) = I _m sinω ₁ t and i _o (f ₂ ) = I _m sinω ₂ t (14)
Thus, despite the fact that the key 7 commutes with a frequency f _o , two signal currents at frequencies f ₁ = f _o -F and f ₂ = f _o + F enter the line.

From the description of the circuit, it follows that in the claimed technical proposal there is no discharge current of the first capacitor 4 to resistor 6, and therefore there are no losses, which for a specific example in the prototype are equal to R _p (DP) = 160 W. It should also be noted that with an increase in the frequency f _о , as follows from (8), the losses increase in direct proportion to an increase in f _о due to an increase in the unit of time of the number of discharge cycles of the capacitor 4 ₁ to resistor 6.

Note. There are a number of positive additional points in the proposed technical solution:
1. For key generators that operate at high voltages, it is practically difficult to use transistors that operate with limited currents and do not hold impulse overloads of hundreds of amperes, so you have to use a thyristor with forced shutdown as a key. It is impossible to apply a transistor for currents at least up to 50 A in the prototype, because at the time of its opening, there will be a large surge in the discharge current of the capacitor 4 ₁ to the resistor R, which is charged up to 530 V. This current can be limited by increasing the resistance of the resistor R, but then the efficiency and useful current will be small.

, заявленным в

раз меньше, т.к. он работает не с линейным напряжением, а с фазным.2. In the prototype, the key is under voltage 530V

declared in

times less because It works not with line voltage, but with phase voltage.

 3. Given the above, we were able to run a generator on a transistor, and the resistance of the resistor R is not 8 Ohms, as in the example, but R = 0, that is, practically have losses in the generator only in wires and circuit elements.

 Conclusions. Thus, the goal set by the invention is proved, i.e. reduced power consumption.

Claims (1)

A generator with a passive-active method of inputting signal currents into a three-phase electric network containing a 10 / 0.4 kV transformer, the low-voltage winding of which phase A is connected to the first output of the first inductor, the second output of which is connected to the first lining of the first capacitor and to the cathode and anode respectively, of the fourth and first diodes, the cathodes of the first and second diodes are connected to the first output of the resistor, the second output of which is connected to the input of the signal key, the output of which is connected respectively to the anodes of the four of the second and third diodes, characterized in that a low-voltage winding of phase C of the transformer 10 / 0.4 kV, a second inductor, which is inductively connected to the first inductor, the second capacitor, the second lining of the first capacitor connected to the first output of the second the inductance coils, the anode and cathode of the second and third diodes, respectively, are connected to the "ground" bus of the transformer 10 / 0.4 kV, the low-voltage winding of the transformer 10 / 0.4 kV phase B is connected to the first output of the second inductor and a second terminal which is connected to the first plate of the second capacitor, the second plate of which is connected to a low voltage side of the transformer 10 / 0.4 kV phase S.

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