SU1252881A1 - Device for controlling rectifier converter of a.c.voltage to d.c.voltage with reactive energy accumulator at output - Google Patents

Abstract

The invention relates to electrical engineering, in particular, to converter equipment, and can be used in devices for controlling thyristor controlled 3 60 (Fig.}

Description

rectifiers and inverters, as well as frequency converters for synchronous and asynchronous electric drives. The aim of the invention is to reduce the installed power of the valve equipment and the reactive energy storage device and increase the reliability of the converter. At the first stage of operation of the control device, when the converter 3 is disconnected, the protection unit 8 is sigalised by the AND-OR elements 26, 27, 28, the AND-NE element 24 and the galvanic isolating elements 7, 21, the control pulse drivers 14 are switched on phases of a multiphase converter 3, one of the valves of which was in a conducting state before the arrival of a signal from the output 18 of the protection unit 8, which corresponds to

The invention relates to electrical engineering, in particular, to converter technology, and can be used in devices for controlling thyristor controllers, rectifiers and inverters, as well as frequency converters for synchronous and asynchronous electric drives.

The aim of the invention is to reduce the installed power of the valve equipment and the reactive energy storage device and increase the reliability of the converter.

FIG. I presents the principle of the electrical circuit of the device for controlling the valve converter; in fig. 2 - diagrams of operation of elements during normal disconnection of the converter; Fig. 3 is the same in the event of an emergency shutdown associated, for example, with a malfunction of the formers (the dotted line in Fig. 2 and Fig. 3 shows the diagram of currents and voltages for a known device).

A device for controlling a valve converter of alternating voltage to constant voltage with reactive

252881

With a minimum load of converter valves 3 emergency currents. At the second stage, in case of failure of the control pulse formers 14, after the voltage on the DC bus 2 of the converter 3 passes through a zero value and the polarity of this voltage is changed, the operation of the driver 14 and the activation of the short pulse former 5 is performed. Thus, the two-stage control of switching on the valves of one phase of the converter 3 significantly improves the reliability of the trouble-free shutdown of the converter 3, while the current of the most loaded ventilation liters and the duration of its no flow prevsh1ayut setpoints. Zil,

the power storage device contains a voltage sensor 1 on the pin 2 of the direct current of the valve converter 3c with the reactive energy storage device 4 at the output, the driver I

5 short-circuit pulses, output connected to the control inputs of the valves 6 and 7 of the same phase

Converter, protection block 8, converter control angle forming block 9, output 10 connected to the counting input 1I of the distributor 12 pulses, outputs 13

connected to the driver control pulses 14 of the converter valves, the node 15 of blocking the output pulses of the distributor, the input 16 of which is intended to

connection through the first razvyvavdi element 17 to the output 1B of the block 8 protection. The second 19, the third 20, the fourth 21, the fifth 22 and the sixth 23 are introduced into the converter.

elements, the first 24 and second 25 elements AND-NOT, elements AND-OR 26-28

the number of valves in the anodic (cathodic) transducer group (for a three-phase bridge circuit

element), trigger 29. Some inputs

30 elements 26-28 are connected to the outputs 31 of the distributor 12 pulses associated with the inputs 32 of the rotary controller of the control pulses of the valves 6 and 7 of the same phase and the valves of the phases 33 and 34 of the converter 3, the other inputs 35 of the elements 26-28 combine connected to the inputs 36 of the fourth 21, an additional 22 and sixth 23 distributing elements. The input of the fourth isolating element 21 is connected to the output 37 of the first NAND element, the input 38 of the trigger setup to one and one input 39 of the second 25 NAND element, the other input 40 of which is connected to the output 41 of the voltage sensor 1 and input 42 Records of the zero state of the trigger 29, the output of the second element 25 is NOT connected to the counting input of the trigger 43, one input 44 of the pulse shaper of the shorting switch 5 and the input 45 of the fifth and the input 46 of the second decoupling elements. The direct output 47 of the trigger is connected to another input 48 of the pulse shaper of the shorting switch 5 by the input 49 of the sixth 23 and the input 50 of the third isolating element 20. The outputs of the first, second and third converting elements are combined and connected to the input 16 of the distributor 15 blocking output pulses . A single state trigger entry 51 is connected to a common bus, the first IS input is NOT connected to the output 18 of the protection unit 8 and the input 52 of the output pulses of the control angle former 9 of the transducer. The outputs 53-55 of the elements 26-28 are connected to the additional inputs 56-58 of the respective driver controllers for the cis impulses of the gates of the converter of one phase. The alternating current lines 59 of the gate converter 3 are connected via a switch 60 to a network 61, which, via the phase converter transformer 62, synchronizes the operation of the converter control angle generating unit 9, which may consist, for example, of switch 63, adder 64 and master oscillator 65 The galvanic isolation elements 17, 19, 20 and 21-23 can be executed either on the three-input logic element

And, either on the diodes, the anode of the elements connected to the output, and the cathode to their input.

FIG. 2 the following notation is adopted: 66 - voltage on DC buses 2; 67 - voltage at the output 41 of the voltage sensor I,

68- current in the DC link;

69- Current most loaded valve short-circuit converter; 70 - signal at the output 18 of the protection unit 8; 71 - signal at the counting input 11 of the distributor 12; 72 - signal at the inputs 35 of the elements 26-28 73 - signal at the inputs 30 of the element 26; 74 - the signal at the output 53 of the element 26; 75 - node output signal

15 blocking the output pulses of the distributor 12; 76 - the signal at the counting input 43 of the trigger; 77 - signal at the direct output 47 of the trigger; 78 - current of valves 6 and 7 of the converter.

A device for controlling a variable-voltage converter-to-constant converter with a reactive energy storage device operates as follows.

During normal operation of the valve converter 3, the signal at the output 18 of the protection unit 8 is absent (a single potential, diagram 70), and at the output 37 of the first element 24 a zero potential is set, which ensures that the trigger 29 is set to the single state at input S 38, blocking the stalls element 25 at input 39 and blocking the operation of elements 26-28 at inputs 35 (figure 72).

In this case, a single potential is set at the input 16 of the node 15 for blocking the output and mycovers of the distributor (diagram 75), since the unit potentials are also supplied to the inputs of the decoupling elements 17-20, which corresponds to unlocking the dual control pulses at the outputs 13 of the pulse distributor 12, except In addition, a single potential at the input 52 of the control angle formation unit permits the passage of the output pulses of the master oscillator 65 to the counting input 11 of the distributor 12 (diagram 71),

The indicated state of the control device remains unlimited.

a draw time regardless of the signals from the output 41 of the voltage sensor 1 and the signals at the outputs 31 of the distributor 12,

At the same time, at the outputs 13 of the distributor 12, dual control pulses of the former 14 are formed (for example, wide pulses with a duration of 120 e. Degrees), and at the outputs 31 of the distributor 12 single ones are formed, of a duration of 60 e. hail, switch control pulses

63 of the control angle forming unit 9.

The signal of the protection unit 8, for example, when an unacceptably low supply voltage, short circuit in the load, overvoltage in the valves or on the DC buses of the converter 13, sets its output 18 to zero potential (figure 70), which leads to blocking the clock output pulses of the control angle block 9 (diagram 71), blocking the dual control pulses of the formers 14 through the decoupling element 17 and preparing to work through the first element 24 of the AND-OR, 26-28 and trigger 29 elements (diagram -72)

Since, as a result of blocking the output pulses of the control angle forming unit 9, the distributor 12 maintains the state prior to the activation of the protection unit 8, there is zero potential on one of its outputs 31, and a unit potential on all other outputs. For definiteness, we assume that there is a zero potential at one of the inputs 30 of element 26 (diagram 73). Since when the protection unit is triggered, the blocking on inputs 35 from elements 26-28 is released (diagram 72), then output 53 of element 26 (diagram 74) has a zero potential that ensures the switching of the formers 14 to control the pulses of the valves 33 of one phase - l 3, In this case, the control pulses will fall on the valves of that phase (in this case, the valves 33), one of the valves of which was in the conducting state before starting the protection unit,

Thus, when turning off the converter, when

it is necessary to reduce the emergency current or to prevent the further development of the accident by switching on the short-circuit switch - i.e. one valve

transducer phases — first, the standard control pulse formers 14 are turned on in that phase, the valve of which, before the protection unit 8 triggered, was in a conducting state of not more than one clock cycle of the master oscillator 65, which ensures the minimum value of the emergency current of the most loaded valve (diagram 79) . If a

a negative voltage is applied to the non-conducting phase valve, the control pulse formers of which are turned on, this valve will not turn on, and the voltage at the output of the valve converter will begin to decrease. the linear voltage envelope before going through the zero value (figure 66, solid line). After the output voltage of the converter 3 has passed through a zero value, when a positive voltage is applied to the non-conducting shoulder valve, further operation of the device for controlling the valve converter can occur in two ways.

X

In the first case, when the control pulse driver of the non-conducting valve produces a normal control pulse ensuring the valve is turned on, the voltage on the DC buses of the DC converter 2 after reaching the zero level remains unchanged, the current of the reactive electron accumulator closes on the switched shoulder of the converter valves and decreases. shifts with a constant time determined by the inductance of the energy storage device and the active resistance of the circuit through which the current of reactive energy flows storage means 4 (figure 68).

In this case, the signal at the output 41 of the voltage sensor 1 (diagram 67) does not change its polarity, which corresponds to a zero potential at the input 40 of the second element 25 and the input 42 of the setting of the trigger 29 to the zero state. Therefore, the second element 25 and, therefore, the trigger 29 do not change their state.

5 is not turned on and the process of switching off the converter takes place in the most favorable way: the minimum current value behind the loaded valve is minimal or close to it, the duration of the emergency current flow (Figure 69).

In the event that the shaper 14 of the control pulses did not ensure that the phase of the converter failed to turn on (for example, due to its malfunction, voltage supply, failure of the valve), then after passing the voltage on the DC bus 2 3 through zero value, the polarity of the output voltage of the converter will change and the voltage in the conducting direction will be applied to the valves 6 and 7 of the converter.

When the polarity of the voltage changes on the DC bus 2, a single potential appears at the output 41 of the voltage sensor 1, which leads, respectively, to the appearance of a single potential at the input 42 — the trigger setting input to the zero state — to input 40 of the second element 25.

As a result, a sync pulse appears at the output of element 25, which acts on the counting input 43 of the trigger (Figure 77). The emergence of a zero potential at the output 47 of the flip-flop 29 causes the galvanic isolation of elements 26-28 to be blocked via element 23 and, consequently, the control pulsers of control pulses 14 are blocked: in addition, the galvanic isolation element 19 blocks the dual control formers of the formers which are formed at the outlets 13 of the distributor.

At the same time, at the input 48 of the pulse former of the short-circuit switch 5, it is switched on and it is subabt control pulses on the 6 and 7 of the converter. Since this driver was in reserve, the reliability of its work is quite high. Turning on the valves 6 and 7 of the converter leads to the closure of the current of the reactive energy accumulator 4 to the turned on valves and its further attenuation, with the same

50

50

0 5

five

0

five

constant time, as in the case of the inclusion of valves 33 as a short-circuit (figure 78).

The inputs 45 and 46 of the galvanic isolation elements 22 and 19 additionally block the operation of control driver formers 14 in case of failure of trigger 29, and an additional signal is applied to input 44 for switching the short circuit breaker 5.

After the converter is turned off, for example, by the current zero signal, a single signal is set in the power circuit at output 18 of the protection unit and the elements return to their initial state.

Thus, the proposed device for controlling the valve converter, by introducing additional elements and a trigger, provides a two-stage operation of the device for controlling when the converter is disconnected by the signal of the protection unit.

At the first stage, the I-ILY 26-28 elements of the 24 NES device and the 21 and 27 galvanic uncoupling elements are used to turn on the formers 14 of control pulses of that phase of the multiphase converter, one of the valves of which was in the conducting state (but not more than 60 e.: degrees | before the signal from the output of the protection unit arrives, which corresponds to switching off the converter with 3 emergency currents with a minimum load of 3 emergency currents (the solid lines in the diagrams of Fig. 2, the dotted lines correspond to the currents when switched on as short the damper of the valves of the same converter phase).

At the second stage, in case of malfunction of the control pulse formers 14, after the voltage on the inverter direct current voltage goes over the zero value and the polarity of this voltage, the operation of the formers 14 and the short pulse forcing unit ) Tatkal 5.

This mode of operation almost guarantees switching off the converter with the lowest possible currents of the busiest valve (diagram 69), which allows to choose the installed power of the converter equipment at a much lower level (approximately half) than dp of the converter with predetermined phase valves used as a shortcut,

The two-stage control of switching on the valves of a single phase converter makes it possible to significantly increase the reliability of a trouble-free shutdown of the converter (the current of the most loaded valve and the duration of its flow do not exceed the specified values).

Claims (1)

Invention Formula A device for variable voltage AC voltage converter with a reactive energy storage at the output, containing a voltage sensor on the DC buses of the converter, a short circuit pulse driver, output connected to the control inputs of the valves of one converter phase, block forming the control angle of the converter, the output connected to the counting input of the pulse distributor, the outputs connected to the driver control pulses of the converters a node, a blocking block for the 1X output pulses of the distributor, the input of which is intended to be connected to the input of the protection unit via the first decoupling element, characterized in that, in order to reduce the installed capacity of the valve equipment and the reactive energy accumulator and increase the reliability of the converter, a second, third , the fourth, fifth and sixth decoupling elements of the first and second elements AND-NOT, the elements AND-OR by the number of valves in the anode Node (cathode) converter group, trigger, converter control angle forming unit are equipped with output pulse blocking input, and control valve pulse shapers of one phase converter are equipped with an additional input, and one inputs of AND-OR elements are connected to the corresponding pulse distributor outputs connected with the inputs of the control pulse formers of the converter gates of one phase, the other inputs of the AND-OR elements are combined and connected to the outputs of the fourth, fifth and higher of a fourth decoupling element, the input of the fourth decoupling element is connected to the output of the first NAND element, the installation input of the trigger in the single state and one input of the second AND-NAND element, the other input of which is connected to the voltage sensor output and the zero recording input trigger, the output of the second element AND- is NOT connected to the counting input of the trigger, one input of the short-circuit pulse shaper, and the inputs of the fifth and second isolating elements, the direct output of the trigger is connected to another input of the trigger l short-circuit pulses and the inputs of the sixth and third decoupling elements, the output of the second and third decoupling elements are combined and connected to the input of the blocking output pulses of the distributor, the recording input of the single state of the trigger is connected to the common gate, the inputs of the first AND-NOT element are intended for connection with the output of the protection unit and are connected to the input of blocking the output pulses of the unit for forming the angle of control of the converter, and the outputs of the elements AND-NOT are connected to the inputs of the corresponding one-phase transducer control valve pulse drivers