RU6478U1 - VARIABLE DISCRETE CONTROL DEVICE - Google Patents

Abstract

1. Device for discrete control of alternating voltage, containing a multi-winding booster transformer with a W-shaped core, on each of the side rods of which there are windings: mains, booster (volt residue) and control with taps, network windings have the same number of turns and are connected in series-opposite , the windings of boost and volt residue have the same number of turns and are connected in series; thyristor switches made of each of two countercurrently connected thyristors, the first switch connected to the end of the control windings, the second switch connected to the next taps from the control windings, etc., the last switch connected to the beginning of the control windings; voltage transformer; setpoint voltage source; comparators, to one, interconnected inputs of which a voltage converter is connected, and voltage sources of the settings are connected to other inputs, one source to each input; two-input logic circuits EXCLUSIVE OR, each input of which is connected to the outputs of two comparators - with the same number and the next; thyristor control pulse generators, and the number of thyristor keys, comparators and logic circuits are equal to each other, characterized in that, in order to simplify the device and increase its reliability, identical generators are used as pulse generators, the number of which is equal to the number of thyristors, with an output circuit, galvanically isolated, for example, by a transformer from a pulse shaping circuit and resolution circuits, moreover, the resolution circuit

Description

VARIABLE DISCRETE CONTROL DEVICE

The invention relates to electric power equipment and can be used for individual voltage regulation at remote sites and for responsible consumers, mainly in the mining industry. Mining enterprises are characterized by wide fluctuations in voltage at remote consumers, which is caused by voltage changes at the main step-down substations, the shift operation of enterprises and cyclic loads of mining. The most promising way of individual voltage regulation at remote and critical facilities is the use of thyristor-switched boost boost transformers (VT).

The device uses the principle of longitudinal voltage regulation and contains three single-phase VTs, a converter, a threshold device, pulse generators, thyristor switches. VTs are used both in voltage boost mode and in voltage mode. The voltage regulation in the secondary winding is stepwise, thyristor switches are included in the winding that controls the distribution of magnetic flux between the transformer rods.

The aim of the invention is to simplify the device and increase its reliability by using as generators of pulses for controlling thyristors the same generators with one output pulse for the period of the synchronizing network, and the number of generators is equal to the number of thyristors. Each generator contains a permit circuit and an output circuit galvanically isolated, for example, by a transformer, from the pulse generating circuit and from the enable circuit, and the circuit

Н02М 5/257, 5/12

the permissions of each two generators connected to the thyristors of the same key are connected by their own permission circuits to the output of one of the logic circuits exclusive OR.

Analogs of the device include:

1. Copyright certificate N440654 KFi.GOSf 1/20;

2. Copyright certificate N696582 class O05P 1/14.

In analogue 1, a device for stabilizing an alternating voltage is provided, containing n voltage boosting transformers, the primary windings of which are shunted by switches. The number of turns of the secondary windings relate to each other, like numbers in binary code. Several transformers can be switched on simultaneously. The disadvantage of this device is the need to use n separate transformers, which increases the size and weight of the device.

In analogue 2, a method for switching booster transformers of a discrete t-phase transistor thyristor regulating variable voltage alternator is shown. A method for switching thyristor switches in the secondary windings of boost transformers involves the removal of pulses from the included group of thyristors to eliminate the short circuit of power transformers. The device contains a separate group of power transformers and a separate group of boost transformers. This complicates the design of the device and the control algorithm of the circuit, which is a disadvantage of the device.

The closest in technical essence to the described device is the device shown in Sat. Electric Machines and Power Systems, 16: 225-238, 1989. The device includes a multi-winding boost transformer with a W-shaped core. On the side terminals of the transformer are two network, two voltage boost (voltage boost and volt residue) and two control windings. Winding

controls are connected in series. Five pairs of taps from the control winding are shunted with five keys from on-parallel connected thyristors. Voltage regulation is carried out by switching on only one of the five keys, and both thyristor switches are turned on with a zero control angle and conduct current for a full voltage period. The boost windings and control windings are turned on in such a way that the sequential and alternating switching on of the thyristor switches leads to the regulation of the output voltage from minimum (lower than rated) to maximum (higher than rated).

The selected group of thyristors is turned on by a control signal (wide pulse or pulse packet), the duration of which is equal to the half-period of the supply network. The thyristor key is selected by five exclusive OR circuits connected to the outputs of five comparators. The voltage from the comparator is applied to one common input of the comparators, the voltage of the settings goes to the other inputs. With a positive voltage at the output of one (j-th) of the five logic circuits, a circuit of control signals supplied to the selected (j-th) thyristor switch is turned on. Switching key management circuits is performed by AND gates. The presence of the And selector and control signal generators with a signal duration equal to the half-cycle of the network complicates the device and requires the presence of powerful pulse generators due to the long duration of the control signals. The generator must be connected to the thyristor control circuits with galvanically isolated keys, for example, optocouplers, designed for switching current up to 0.6 A during Hume (half-cycle duration at the network frequency

50 Hz). To switch the etching circuit of each thyristor, two keys are required: in the cathode circuit and in the control electrode circuit.

The aim of the invention is to simplify the device and increase its reliability. The goal is achieved by the fact that the And selector circuit is canceled, and 2n low-power generators with one pulse for the period of the supply network, where n is the number of thyristor switches, are used as control pulse generators. The inclusion of the selected pair of pulse generators is controlled directly by the output signal of the corresponding exclusive OR. Low-power pulse generators can be performed in integral design.

Figure 1 shows a block diagram of the inclusion of boost boost transformers in a three-phase load circuit.

Figure 2 shows the connection diagram of the windings of the boost transformer and thyristor keys.

Fig. 3 shows a block diagram of a thyristor switch control system for one boost booster transformer.

In FIG. 4 is a schematic diagram of one channel of a control system.

Figure 5 shows the voltage diaphragm in the control system.

The device contains three boost boost transformers 1, the output circuits of which are connected to a three-phase load 2. A voltage measuring transducer 3 is connected to the transformer power supply circuits. The output voltage circuits of the transducer 3 and the voltage sensors of the settings 4 are connected to the inputs of the comparison unit to the comparators 5. The output circuits of the comparators 5 connected to logic circuit 6, the output circuits of which are connected to the input control switch

pulse generators 7. The output circuits of the generators 7 are connected to the control circuits of the thyristor switches 8.

Booster transformer 1 contains a W-shaped core with a closed magnetic circuit (figure 2). The direction of magnetic fluxes in the core rods is indicated by a dotted line. Two primary windings 9, 10 have the same number of turns and are connected in series opposite. The windings 11, 12 are connected in series with the load 2 of one phase with such a polarity that one winding 11 works in the direction of increasing voltage in the sleeve 2, and the second winding 12 in the direction of lowering. Magnetic flux control in the windings 11,12 is carried out by switching the control windings 13, 14. The same keys 15 ... 20 are connected to the taps of the windings 13, 14, each of which consists of on-parallel connected thyristors. The number of turns of the windings 13 and 14 is the same. The taps from the windings 13, 14 are made depending on the required magnitude of the voltage steps with discrete regulation of the voltage in the load 2. The input alternating voltage is connected to the input terminals 21, 22.

The thyristor control circuit of each phase of the device contains n (for example, 6) comparators 23 ... 28, a logic circuit of n two-input exclusive OR 29 ... 34, 2n pulse generators 35 ... 46 (Fig. 3). The output of each generator is connected to the control circuits of one thyristor: the generators 35, 36 are connected to the thyristor key 15, the generators 37, 38 are connected to the key 16, etc. The output of the voltage converter 3 is connected to one common input of the comparators 23 ... 28, the outputs of the sensors 4 of the setpoint voltage with voltages U1 ... U6 are connected to the second inputs of the comparators (Fig. 5). The inputs of the circuits 29 ... 33 are each connected to the outputs of two comparators: the inputs of the circuit 29 are connected to the outputs of the comparators 23, 24, the inputs of the circuit 30 are connected to the outputs of the comparators

24, 25, etc. The input of circuit 34 is connected to the output of comparator 28. The outputs of circuits 29 ... 34 are each connected to the unlocking circuit of two generators controlling one of the groups of thyristors: the output of circuit 29 is connected to generators 35, 36, etc.

The device operates as follows. The inclusion of thyristor switches leads to the shunting of part of the control windings 13, 14, to a change in magnetic fluxes in the rods of the transformer 1 and to a change in the output voltage. The inclusion of the key 20, shunting the control winding 13, leads to a maximum decrease in voltage at the load; the inclusion of the key 15, shunting the control winding 14, leads to a maximum increase in voltage at the load. The inclusion of one of the intermediate switches 16 ... 19 allows you to stepwise adjust the voltage across the load between the minimum and maximum levels.

The output voltage of the Converter 3 is supplied to the input of all comparators 23 ... 28. Comparison voltages (settings) U1 ... U6 of sources 4 differ from each other (see Fig. 5). The voltage of the source 4 connected to the first comparator 23 has the smallest value, the voltage at the outputs of the second, third, etc. sources 4 increase, the voltage of the sixth source 4 has the largest value U6. When the voltage at the output of the converter 3 exceeds the comparison voltage, the voltage at the output of the comparator jumps into the positive zone (U23 ... U28, see figure 5). For the specified distribution of the comparison voltage levels U1 ... U6 and with increasing voltage at the output of the converter 4 from zero to a maximum value exceeding U6, the comparators 23 ... 28 are switched one after another. At the same time, at the outputs of the circuits 29 ... 34, positive voltage drops U29 ... U34 alternately occur and the groups of thyristors 15 ... 20 are also alternately switched on.

Consider the circuit for switching on one thyppa fuppa (Fig. 4), for example, key 15. Turning on the thyristors 47, 48 of key 15 is performed by pulses from the generators 35, 36, respectively. Each generator is synchronized by voltages U35, U36, synchronous with the anode voltages of thyristors 47, 48, respectively. The generator includes a Schmidt trigger 49 and a pulse shaper (standby multivibrator) 50, at the output of which a pulse transformer 51 is turned on. The circuits of the generators 35 and 36 are the same. At the output of the generator 35, one pulse U51 is generated for one period of the synchronizing voltage U35 (see Fig. 5) if the output voltage U29 of the circuit is exceptional OR 29 is positive. Similarly, a pulse is also generated at the output of the generator 36 if the output voltage of the circuit 29 is positive. The control pulse is generated, for example, by an analog timer КР1006ВИ, while the control by the timers of the generators 35, 36 is controlled by the voltage from the output of the circuit 29 connected to the enable input E of the timers of the generators 35, 36. Thus, when the positive voltage permits the output of the circuit 29, control circuits of thyristors 47, 48 receive control pulses. Control pulse width μs.

The use of identical pulse generators with one short (up to 100 μs) pulse per network period allows reducing the power of each generator and executing each generator or group of several generators in integral design. In addition, the logical control pulse distributor, which distributes the pulses between two pulse generators and two control circuits, is excluded. Given that the logical distributor must galvanically isolate pulse generators and thyristors, it should be based on, for example, thyristor or transistor optocouplers, the number of which

twice the number of thyristors. The need to use a generator with a wide pulse (or pulse packet) at the output is also eliminated, which additionally reduces the generator capacity.

It is possible to execute a circuit of pulse generators controlling the thyristor keys of one transformer using only two Schmidt synchronizing triggers. At the same time, an alternating voltage source of one phase is connected to the input of one trigger, and an alternating voltage source with a phase shifted by 180 electrical degrees relative to the first source is connected to the input of another trigger; half of the waiting multivibrators are connected to the output of one Schmidt trigger, and the second half to the output of the other trigger.

Claims (3)

1. Device for discrete control of alternating voltage, containing a multi-winding booster transformer with a W-shaped core, on each of the side rods of which there are windings: mains, booster (volt residue) and control with taps, network windings have the same number of turns and are connected in series-opposite , the windings of boost and volt residue have the same number of turns and are connected in series; thyristor switches made of each of two countercurrently connected thyristors, the first switch connected to the end of the control windings, the second switch connected to the next taps from the control windings, etc., the last switch connected to the beginning of the control windings; voltage transformer; setpoint voltage source; comparators, to one, interconnected inputs of which a voltage converter is connected, and voltage sources of the settings are connected to other inputs, one source to each input; two-input logic circuits EXCLUSIVE OR, each input of which is connected to the outputs of two comparators - with the same number and the next; thyristor control pulse generators, and the number of thyristor keys, comparators and logic circuits are equal to each other, characterized in that, in order to simplify the device and increase its reliability, identical generators are used as pulse generators, the number of which is equal to the number of thyristors, with an output circuit, galvanically isolated, for example, by a transformer from the pulse forming circuit and the resolution circuits, and the resolution circuit each of two generators connected to the thyristors of the same key, connect enes to the output of a logic EX-OR.  2. The device according to claim 1, characterized in that, in order to reduce the power of the generators and reduce their mass and energy consumption, each generator is made according to a circuit that includes a Schmidt trigger and a waiting multivibrator connected to its output with an output pulse of up to 100 μs duration and the following once during the period of the supply network, and the output of the logic circuit is connected to the enable inputs E of the waiting multivibrators, made, for example, on the basis of the KR1006VI timers. 3. The device according to claim 1, characterized in that for the pulse generators that control the thyristor switches of one transformer, it contains two Schmidt triggers, an alternating voltage source of one phase is connected to the input of one trigger, an alternating voltage source is connected to the input of the second trigger phase shifted by 180 el. relative to the phase of the first source, and the inputs of the synchronizing circuits of half of the total number of waiting multivibrators are connected to the output of one Schmidt trigger, and the synchronizing inputs of the second half to the output of another Schmidt trigger.