RU1774433C - Pulse synchronizer - Google Patents

Abstract

Usage: in electrical engineering, is designed to automatically turn on synchronous generators in parallel operation and is additional to A.S. No. 1140204. SUBSTANCE: three-phase phase-shifting device is additionally introduced into a pulse synchronizer. Four of its inputs are connected to the terminals of the three phases and neutral of the synchronized generator, four outputs to the phase and linear generator inputs of the input blocks, in this case pairs of the same name with phase and linear network inputs of these blocks are formed. This makes it possible to use the synchronizer with both high-speed and slow-acting 4-il circuit breakers.

Description

The invention relates to the field of electrical engineering, is intended to automatically turn on synchronous generators for parallel operation and is additional to copyright certificate No. 1140204.

The Known Method for automatically turning on the backup power supply of consumers with motor load (A.S. No. 1297169, CL H 02 J 9/06) and A method of obtaining a constant lead time for automatic re-switching with catching synchronism (AS No. 186009, cl .21 C 68/60), in which, in order to ensure large lead angles with high accuracy, the command to turn on the generator circuit breaker is issued at the moment of synchronized phase shift of the synchronized voltage, and the voltage vector of a lower frequency is shifted by the lagging side, and the voltage vector of a higher frequency is ahead of the curve, so that the resulting angle

shear is determined by the frequency and slip acceleration and the on time of the switch.

In this case, the same phase voltages of synchronized sources are used, and the operation of the indicated shift of synchronized voltages is realized using rather complex and therefore expensive controlled electrically phase-shifting devices of analogue (AS No. 186009) or discrete-pulse (AS No. 1297169 ) types. In turn, obtaining the signal necessary to control the phase shifting devices also requires the use of rather complex and expensive meters — frequency converters and accelerating the slip into the control voltage.

As a result, the goal is achieved due to a significant complication of synchronizers with their corresponding rise in price. It is for this reason that the indicated technical solutions are found at

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change only in synchronizers with constant lead-time, used in power supply systems with critical power receivers. A positive effect - increased synchronization accuracy - is achieved in them due to the complexity and cost of devices.

Closest to the proposed technical essence is the Pulse synchronizer according to the copyright certificate of the USSR No. 1140204, class. H 02 J 3/42. 1983.

The pulse synchronizer contains six identical input blocks, each of which contains two pulse shapers that trigger when the positive half-wave voltage passes through zero, and two pulse shapers that trigger when the negative half-wave of the synchronized voltages passes through zero, two logical circuits AND, an intermediate circuit OR , a frequency control unit, consisting of an auxiliary driver and a D-trigger, circuit I,

A disadvantage of the known synchronizer is its limited scope. It can only be used with high-speed circuit breakers whose tripping time is zero, for example, thyristor or transistor. It is not possible to use a synchronizer with slow acting switches, because the synchronization lead angle of the synchronizer is zero.

An object of the invention is to expand the functionality of a synchronizer.

This goal is achieved by the fact that a three-phase phase-shifting unit is additionally introduced into the pulse synchronizer, four inputs of which are connected to the terminals of three phases and the neutral of the synchronized generator, four outputs to phase and linear generator inputs of the input blocks so that they form the same pairs with phase and linear network the inputs of these blocks.

In FIG. 1 shows a diagram of a pulse synchronizer; Fig. 2 is a vector diagram of synchronized voltages; Fig. 3 and 4 are timing diagrams of the operation of the synchronizer.

The synchronizer (figure 1) consists of a three-phase phase-shifting unit 1, six identical input units 2-7. each of which contains pulse shapers 8–9, triggering when the negative half-wave of the voltage of the mains and generator passes through zero, and pulse shapers 10–11. triggered by the transition through zero of the positive half-wave of synchronized voltages, logic circuits I 12-13. the inputs of which are connected to the outputs of the corresponding

shapers, and the outputs of the circuits AND of all input blocks are connected to the inputs of the intermediate circuit OR 14, the output of the pulse shaper 9 of the first input block that is triggered by the beginning of the negative

half-wave voltage of the generator, connected to auxiliary shaper 15. the output of which is connected to the information input of the D-trigger 17, and the gate input of the D-trigger is connected to the output

pulse shaper 11 of the first input unit, triggered by the beginning of the positive half-wave voltage of the generator, the output of the D-trigger 17 is connected to one of the outputs of the circuit And 18, the other input

which is connected to the output of the intermediate circuit OR 14. A signal 19 to turn on the switch is generated at the output of the circuit AND 18.

The synchronizer works as follows

way.

The phase-shifting unit 1 shifts to the backward side by a predetermined angle d0n all three phase voltages of the synchronized generator Ed, Ev. EU In this case, the linear voltage of the generator - Edv, Eve-ECA, is automatically shifted to the same angle 50p. A vector diagram of the synchronized voltages for phase A is shown in Fig. 2 for the case when the generator frequency fr is less than the mains frequency fc. The voltage at the output of the phase-shifting device Ed is shifted towards the lagging angles with respect to the voltage of the generator Ed at an angle of 5 op. When fr fc, the vectors

move towards the vector UA so that at first there will be a coincidence in phase of the vectors Ed and id. At the moment of coincidence, a command to turn on the circuit breaker is generated. From the diagram it follows that the angle between the synchronized voltages at the time of formation of the command will be equal to a predetermined lead angle of 30l.

When the voltage of the network and the shifted voltage of the generator pass through zero

pulse shapers 8-11 of the input blocks 2-7 produce short pulses (FIG. 3 and FIG. 4). With the coincidence of pulses at the inputs of at least one of the circuits And 12-13 input blocks pulses from the output of this

the circuit through an intermediate circuit OR 14 is fed to one of the outputs of the circuit And 18 in the circuit circuit of the switch 19. If at this moment the pulse from the frequency control unit 16 arrives at the other input of the circuit And 18, then

at the output of circuit And 18, a pulse is issued to turn on the switch. During the operation of the switch, the real voltage vector of the synchronized generator coincides with the voltage vector of the network (Fig. 2).

In the pulse synchronizer, the frequency synchronization of the synchronized voltages leads to the fact that the pulses from the shapers 8, 9 of the first input block are shifted relative to each other in steps. Moreover, pulses of a higher frequency are approaching pulses of a lower frequency from the trailing edge. The step length is determined by the expression

g -Tm-Tg- -1-1 - fs T ™ - Tm 1 B - fM fЈ - fm. fБ

 Tm-tb

xfs

where Tm is the period of the synchronized voltage, the frequency of which is less than tm;

TB - period of synchronized voltage, frequency fs of which is greater;

fs is the slip frequency of one voltage relative to another.

As the slip increases, the step length increases, so when pulses are shorter than the step length, the pulses may jump. This phenomenon is illustrated in Fig. 3 by the example of phase A. So, if in the first period the pulse is generated at the beginning of the negative half-wave Ed, the output of the driver 11 is ahead of the corresponding pulse UA (the output of the driver 9), then in the next period due to the fact that the frequency If the synchronized generator is less than the mains voltage frequency, this pulse lags behind (Fig. 3).

In this case, the transition from leading to lag is not accompanied by the coincidence of the pulses in time and, consequently, the operation of the device, although during this period of time the phases of the synchronized voltages coincided.

To eliminate this drawback, the pulse synchronizer is made multi-channel with the number of channels equal to 12. The multi-channel synchronizer is provided by connecting it to the phase and linear voltages of the synchronized sources and using fixed jHbix phases 0 and 180 °. For a multi-channel device, the step length is determined by the expression

f t

Tm tb p

fs

0 5

0

5

0 5 0

5

0 5

where n is the number of pulses in the period. That is, an increase in the number of pulses leads to a decrease in the step length

It can be seen from Fig. 3 that in this case, the coincidence of the pulses in the And circuit for a given synchronization time took place in block 7, where the phase matching of the synchronized sources was detected by the voltage E CA and UCA.

The appearance of a pulse at the output of the intermediate OR circuit determines the condition (one of two) for the circuit breaker to be turned on, the second condition is associated with the frequency control unit.

Frequency control is carried out once a period as follows

The auxiliary pulse shaper 15 at the beginning of the negative half-cycle of voltage Ed generates a pulse of constant duration (Fig. 4), which arrives at the information input of the D-flip-flop 17, and a pulse from the former 11 (Fig. 3) is supplied to the gate input of the D-flip-flop. voltage triggered at the beginning of a positive half-cycle The pulse duration from the driver 15 is chosen such that, with an allowable difference between the frequencies of the voltage of the UA network and the voltage of the generator Ed, it covers the gate pulse from the driver 11 with its trailing edge, which, in turn, leads to the appearance of a logical unit at the output of the trigger 17 ( Fig. 3), which is connected to the output of circuit AND 18 in the switch on circuit.

Thus, switching on the proposed synchronizer of a three-phase phase-shifting unit will expand its functionality — use it with any, not just high-speed circuit breakers, while achieving acceptable synchronization errors and, therefore, permissible disturbances in the power supply system.

A three-phase phase regulator or a three-phase differential selsyn can be used as a three-phase phase-shifting unit.

Claims (1)

The claims Pulse synchronizer according to ed. St. No. 1140204, characterized in that. that, in order to expand the functionality, it is equipped with a three-phase phase-shifting unit, the four inputs of which are connected to the terminals of the three phases and the neutral of the synchronized generator, and the four outputs are connected to the phase and linear generator inputs of the input blocks so that they form the same pairs with phase and linear network inputs; x blocks A And- j Is. U Fiz. i F. a