RU2765226C1 - Ac voltage regulator - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering, in particular to converter technology, and can be used to regulate voltage and reactive power in electrical networks, as well as to limit short-circuit currents in electrical networks. The substance of the invention lies in the fact that in the circuit diagram of a thyristor voltage regulator containing the main and booster transformers, the first and second thyristor switches, a phase-sensitive unit made in the form of two measuring transformers, two zero-elements, a logical element " AND", a comparison unit, made in the form of a zero-organ, logical elements "OR" and "AND", two amplifiers, a voltage measuring transformer, an auxiliary zero-organ, in a phase-sensitive block, a logical element "AND" is made with three inputs, the third input of which is connected to the output of an additional logical element "NOT", to the input of which a signal of emergency control is received, which transfers the AC voltage regulator to the mode of limiting short-circuit currents.

EFFECT: regulation of voltage and reactive power in electrical networks and limitation of short-circuit currents in electrical networks.

1 cl, 1 dwg

Description

The invention relates to electrical engineering, in particular to converter technology, and can be used to regulate voltage and reactive power in electrical networks, as well as to limit short-circuit currents in electrical networks.

A variable voltage regulator is known - patent No. 2612621 C2 of the Russian Federation, V.N. Krysanov, Yu.V. Sharapov; Federal State Budgetary Educational Institution of Higher Education "Voronezh State Technical University" - 2014145372; 11/11/2014; 03/09/2017, Bull. No. 7 - containing the main and booster transformers, the first and second thyristor switches, a phase-sensitive unit made in the form of two measuring transformers, two zero-organs, a logical element "AND", a comparison unit made in the form of a null-organ, logical elements "OR ” and “AND”, an amplifier, the output of which is connected to the control electrodes of the first thyristor switch, a delay element, the input of which is connected to the measuring voltage transformer through an auxiliary zero-organ, an amplifier, the output of which is connected to the control electrodes of the second thyristor switch, the measuring voltage transformer, auxiliary zero-organ, the input of which is connected in parallel with the output of the measuring voltage transformer, and its output is connected through the delay element to one of the inputs of the auxiliary logic element "AND", the second input of which is connected directly to the output of the comparison unit, and its output - to the control electrodes of the second thyristor key and through the amplifier, the logical element "AND", one of the inputs of which is connected to the output of the comparison unit through the logical element "NOT", and the second input of the logical element "AND" through the delay element and the auxiliary zero-organ is connected in parallel to the output of the measuring voltage transformer, the output logic element "AND" is connected to the input of the auxiliary logic element "OR", the second input of which is directly connected to the output of the phase-sensitive block, and the output of the auxiliary logic element "OR" is connected through an amplifier to the control electrodes of the first thyristor switch, an additional adjustable delay element, the input of which connected to the amplifier output and one of the control electrodes of the second thyristor switch, and the output is connected to another control electrode of the second thyristor switch.

The disadvantage of this device is the inability to work in an additional mode of limiting the short circuit current in electrical networks.

The invention is aimed at obtaining a new quality, namely, an additional short-circuit current limiting mode in electrical networks.

This is achieved by the fact that a logic element "AND" with three inputs is introduced into the phase-sensitive unit, the third input of which is connected to the output of an additional logic element "NOT", which switches the AC voltage regulator to the mode of limiting short-circuit currents.

The technical essence of the invention is illustrated by the general scheme in Fig. one.

The regulator contains a main transformer 1 and a booster transformer 2, thyristor switches 3 and 4, a phase-sensitive unit 5, made in the form of measuring transformers 6 and 7, zero-organs 8 and 9, a logic element "AND" 10, the third input of which is connected to the output of the logic element "NOT" 26, comparison unit 11, made in the form of a null body 12, logic elements "OR" 13 and "AND" 14, amplifier 15, the output of which is connected to the control electrodes of the thyristor switch 3, delay element 16, the input of which is connected to the measuring voltage transformer 18 through the auxiliary zero-organ 19, the amplifier 17, the output of which is connected to the control electrodes of the thyristor switch 4, the measuring voltage transformer 18, the auxiliary null-organ 19, the input of which is connected parallel to the output of the measuring voltage transformer 18, and its output through delay element 16 is connected to one of the inputs of the auxiliary logic element "AND" 20, the second input of which is connected directly to the output of the comparison unit 11, and its output - with the control electrodes of the thyristor switch 4 through the amplifier 17, the logic element "AND" 23, one of the inputs of which is connected to the output of the comparison unit 11 through the logic element "NOT" 21, and the second input logic element "AND" 23 through the delay element 22 and the auxiliary zero-organ 19 is connected in parallel to the output of the measuring voltage transformer 18, the output of the logic element "AND" 23 is connected to the input of the auxiliary logic element "OR" 24, the second input of which is directly connected to the output of the phase-sensitive block 5, and the output of the auxiliary logic element "OR" 24 is connected through the amplifier 15 with the control electrodes of the thyristor switch 3, an additional adjustable delay element 25, the input of which is connected to the output of the amplifier 17 and one of the control electrodes of the thyristor switch 4, and the output is connected to another the control electrode of the thystor key 4.

The device works as follows. In the voltage regulation mode, at the moment when the supply voltage is applied to the main transformer 1, voltage appears on the thyristors 3 and 4, which is supplied through the measuring transformers 6 and 7 of the phase-sensitive unit 5, and zero-organs 8 and 9 to two inputs of the logic element "AND" 10, at its third input there is a permission signal from the output of the logic element "NOT" 26. Next, the voltage is supplied through the measuring voltage transformer 18 and null body 12 to the input of the logic element "AND" 14 of the comparison unit 11 and the delay element 16 through auxiliary null-organ 19. The generated signal from the output of the phase-sensitive block 5 is fed through the logic element "OR" 24 to the input of the amplifier 15, which processes the signal at its output, and to the input of the logic element "OR" 13, resulting in the output of the block comparison 11, a voltage appears, which is maintained until the mains voltage passes through zero.

From the output of the comparison unit 11, the signal is fed to one of the inputs of the AND logic element 20, the other input of which receives a signal from the output of the delay element 16, which is triggered at the moment the voltage passes through zero.

Further, according to the signal that appeared at the output of the amplifier 15, the thyristor switch 3 opens, which leads to the removal of the signal at the output of the phase-sensitive unit 5.

In turn, in accordance with the given adjustment angle, a pulse is generated at the output of the delay element 16, which is fed through the logic element "AND" 20 and amplifier 17 to the adjustable delay element 25 connected to one of the control electrodes of the thyristor switch 4, the output of which is connected with another control electrode of the thyristor switch 4. In this mode of voltage regulation, the delay of the regulated element 25 has a zero value.

Turning on the thyristor key 4 leads to turning off the thyristor key 3, since the latter is under reverse voltage, i.e. introduction of booster EMF from the primary winding of booster transformer 2 into the power circuit of the main transformer 1.

The opening of the thyristor key 4 leads to the removal of voltage at the output of the auxiliary null-organ 19 and its appearance at the output of the null-organ 8.

This state of the circuit is maintained until the moment when the mains voltage passes through the zero value, and for a short time, as a result, the voltage disappears at the outputs of the null-organ 12 and the auxiliary null-organ 19, which leads to the removal of the signal at the output of the delay element 16 and the output of the block comparisons 11.

In this case, the state of the thyristor keys 3 and 4 does not change, the thyristor key 3 is closed, and the thyristor key 4 conducts current until the moment when the load current passes through zero, after which the thyristor key 4 turns off naturally and the voltage appears at the output of the auxiliary zero- body 19.

Thus, the booster EMF is input during the time from the moment the current passes through zero until the voltage passes through zero.

To implement the input of a booster EMF during the time from the moment the voltage passes through zero to the moment the current passes through zero, it is necessary to control the moment of switching on the thyristor key 3, which is carried out using the delay element 22, the logic element "AND" 23, the logic element "NOT" 21 , auxiliary logic element "OR" 24.

Logic element "NOT" 21 inverts the signal from the output of the comparison unit 11, thereby creating at the output of the logic element "AND" 23 the condition for the passage of the control signal from the output of the delay element 22 to the input of the auxiliary logic element "OR" 24 and then to the input of the amplifier 15, only during the time from the moment the voltage passes through the zero value until the moment the current passes through zero.

The supply of a signal from the output of the auxiliary zero-organ 19 ensures the launch of the delay element 22 and the subsequent removal of the signal from its output at the moments when the mains voltage passes through the zero value.

In the case of a signal from the output of the delay element 22 during the time from the moment the current passes through zero to the moment the voltage passes through zero, the passage of the signal to the auxiliary logic element "OR" 24 is blocked by the absence of an enabling signal at the output of the logic element "NOT" 21.

In the case of a signal from the output of the delay element 22 during the time from the moment the voltage passes through zero until the current passes through zero, the thyristor switch 3 is turned on.

Turning on the thyristor key 3 leads to turning off the thyristor key 4, since the latter is under reverse voltage.

This state of the circuit is maintained until the moment when the current passes through zero. At this moment, the switch 3 turns off naturally and the voltage appears at the output of the null-organ 9 of the phase-sensitive block 5.

Further processes proceed similarly to those described above in the voltage regulation mode.

In the reactive power control mode, the operation algorithm of the switching control system for thyristor switches 3 and 4 remains the same (the possibility of changing the level of the introduced booster EMF), with the only difference being that, thanks to the adjustable delay element 25, various moments of turning on the thyristors of the switch 4 are realized (changing the open time thyristors key 4). At the same time, a constant component in the harmonic composition of the voltage on the booster transformer 2 is formed, controlled by the delay element 25, which changes the reactive power consumed by the transformers 1 and 2.

In the additional mode of limiting the short-circuit current in electrical networks (in the case when a short circuit occurs in the electrical network), a signal appears at the input of the logic element "NOT" 26. At its output, the permission signal disappears, coming to the third input of the logic element "AND" 10 , control signals are removed to amplifiers 15, 17, which leads to disconnection of the control winding of the booster transformer from the tertiary winding of the main transformer. In this mode, the booster transformer will work like a choke (its inductive resistance will increase sharply, while the short-circuit current flowing through transformer 1 and booster transformer 2 will decrease significantly).

Thus, due to the implementation of an additional "choke" mode (with an open secondary winding of the booster transformer), by introducing an "AND" logic element with three inputs into the phase-sensitive block, the third input of which is connected to the output of an additional "NOT" logic element, which transfers the variable regulator voltage in the mode of limiting short-circuit currents, this device allows you to eliminate such disadvantages as the inability to work in an additional mode of limiting short-circuit current in electrical networks.

Device implementation example

The invention relates to electrical engineering, in particular to converter technology, and can be used to regulate voltage and reactive power in electrical networks, as well as to limit short-circuit currents in electrical networks.

The essence of the invention lies in the fact that the device contains the main and booster transformers, the first and second thyristor switches, a phase-sensitive unit, logic elements that provide operation in several modes: adjustable voltage boost mode (main mode), reactive power control mode (additional mode), and also in emergency "choke" mode (with an open secondary winding of the booster transformer). In emergency mode (in the case when a short circuit occurs in the electrical network), using a signal about the occurrence of a short circuit, the control system of the device blocks the impulses to open the thyristor switches, which leads to disconnection of the control winding of the booster transformer from the tertiary winding of the main transformer. In this mode, the booster transformer will work like a choke (its inductive resistance will increase sharply, while the short-circuit current flowing through the main and booster transformers will decrease significantly).

The advantage of such a solution is the possibility of creating a multifunctional power transformer device that allows both regulation of voltage and reactive power in electric power systems of various voltage levels, and limitation of short-circuit currents during emergency modes in them.

Scope - high-voltage electric power systems.

This device is characterized by a high degree of novelty. In the second thyristor key, in order to limit the short-circuit current in electrical networks, it is introduced in a phase-sensitive unit, instead of the logical element "AND" with two inputs, the logical element "AND" with three inputs, the third input of which is connected to the output of an additionally introduced logical element "NOT", transferring the AC voltage regulator to the mode of limiting short-circuit currents. In the course of research, the development of the optimal structure of the control system of this device for various voltage levels, electric power systems was carried out. When introducing this device into production, a significant effect from the implementation is expected.

One of the possible ways of commercial implementation of this device is its implementation in modern power supply systems, which will ensure a stable voltage level, an optimal balance of reactive power in electric power systems, taking into account various consumption modes, and protection against short circuit currents.

For educational purposes, this program can be supplemented with a laboratory stand that simulates either an entire electric power system, which will include AC voltage regulators, or a separate AC voltage regulator (in the form of a linear regulator), which will be able to maintain a constant required voltage level and compensate for reactive power, to carry out effective protection against short circuit of an individual consumer of electrical energy (for voltages from 0.4 kV to 10 kV). This laboratory stand will present in practice modern technologies for regulating alternating voltage and reactive power compensation, combined with protection against short circuits in the network. The described device can be used in the course of laboratory work on the discipline "General Energy", "Power Supply", "Converting Technology".

Claims (1)

AC voltage regulator, including the main and booster transformers, the first and second thyristor switches, a phase-sensitive unit made in the form of two measuring transformers, two zero-organs, an AND logic element, a comparison unit made in the form of a null-organ, logic elements " OR" and "AND", the first amplifier, the output of which is connected to the control electrodes of the first thyristor switch, the delay element, the input of which is connected to the measuring voltage transformer through an auxiliary zero-organ, the second amplifier, the output of which is connected to the control electrodes of the second thyristor switch, measuring voltage transformer, an auxiliary zero-organ, the input of which is connected in parallel with the output of the measuring voltage transformer, and its output is connected through a delay element to one of the inputs of the auxiliary logic element "AND", the second input of which is connected directly to the output of the comparison unit, and its output - to driving them with the electrodes of the second thyristor switch through the second amplifier, the logical element "AND", one of the inputs of which is connected to the output of the comparison unit through the logical element "NOT", and the second input of the logical element "AND" through the delay element and the auxiliary zero-organ is connected in parallel to the output measuring voltage transformer, the output of the logic element "AND" is connected to the input of the auxiliary logic element "OR", the second input of which is directly connected to the output of the phase-sensitive unit, and the output of the auxiliary logic element "OR" is connected through the first amplifier to the control electrodes of the first thyristor switch, additional adjustable delay element, the input of which is connected to the output of the second amplifier and one of the control electrodes of the second thyristor switch, and the output is connected to another control electrode of the second thyristor switch, characterized in that the logic element "AND" in the phase-sensitive block is made with three inputs, third whose input is connected to the output of an additional logic element "NOT", which switches the AC voltage regulator into the mode of limiting short-circuit currents.

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