RU196697U1 - Multilevel Voltage Converter Module - Google Patents

Abstract

The utility model relates to the electric power industry and can be applied in modular multilevel voltage converters. The technical result of the utility model is to ensure the operation of the module without using an independent power source, reducing the control power and the required capacity of the buffer capacitor. The module contains a conversion cell (1) with a buffer capacitor (2 ), a bypass contactor (3), designed to bypass the converter cell (1) in case of its failure, and a control unit (4) equipped with a pit block (5) from the buffer capacitor (2). Bypass contactor (3) is made in the form of a pair of on-parallel connected thyristors (6) and (7), the control transitions of which are shunted in the opposite direction by diodes (10) and (11). The control electrodes (8) and (9) of the thyristors (6) and (7) are connected through the contact (12) of the pulse relay (13), controlled from the output (15) of the control unit (4). 2 ill.

Description

The field of technology.

The utility model relates to the electric power industry and can be used in modular multilevel voltage converters used in medium-high voltage electric networks as various means of reactive power compensation, active filter-balancing devices, and also as converters in DC transmissions and inserts and frequency -regulated electric drives.

State of the art

High reliability of modular multilevel converters is ensured by the use of an excessive number of modules connected in series in the converter phases, each of which is equipped with a bypass circuit - a means of bypass in case of failure.

A well-known multilevel converter module comprising a converter cell with a buffer capacitor and a bypass circuit shunting it, made in the form of two IGBT transistors connected by emitters and two diodes connected counter-parallel to these transistors [RU 107422].

A disadvantage of the known solution is that in order to maintain the bypass circuit on, a continuous control current is required and, accordingly, a power source independent of the voltage on the shunt converter cell.

A known multilevel converter module comprising a conversion cell with a buffer capacitor, a bypass contactor shunting the conversion cell, and a control unit provided with a power supply from said buffer capacitor [RU 2455723]. This device is selected as a prototype.

In order to reduce (or eliminate) the dependence of the power supply of the control unit (which controls both the converter cell and the bypass contactor) on the voltage on the buffer capacitor, the prototype uses a bypass contactor in the form of a vacuum interrupter, the implementation of which is illustrated in FIG. 1 (copied from FIG. 4 the description of patent RU 2455723).

The bypass closure of the prototype is made in the form of a vacuum interrupter 100, a fixed contact 111 and a movable contact 112 which bypass the converter cell. The chopper 100 is held open by a permanent magnet field 330 that closes through a soft soft yoke 320. The action of the permanent magnet 330 is momentarily blocked by a counter external magnetic field created by a winding 340 wound on the yoke 320. Under the influence of atmospheric pressure, the movable contact 112 of the chopper 100 is drawn into the vacuum chamber before contact with the fixed contact 111 and, thus, closes the bypass circuit. After current attenuation in coil 320, the bypass circuit remains closed, as the attraction force of the permanent magnet 330 is not enough to extend the movable contact 112 of the chopper from the vacuum chamber.

As follows from the patent description of the prototype (Fig. 5 and lines 30-35 on page 11 of the description of patent RU 2455723), a separate (independent of the voltage on the buffer capacitor) power supply is required for generating a current pulse in the winding 340 controlling the bypass contactor ( 410 in Fig. 5 of the description of patent RU 2455723) and “a powerful semiconductor device that can be controlled by a thyristor or IGBT”. In another embodiment of the bypass contactor of RU 2455723 (without a permanent magnet 330), the vacuum interrupter is held open by current flowing continuously through the winding 340 during operation of the operational converter cell.

Utility Model Essence

The technical result of the utility model is to ensure the operation of the module without using an independent power source, reducing the control power and the required capacity of the buffer capacitor.

The object of the utility model is a multilevel voltage converter module comprising at least one converter cell with a buffer capacitor, a bypass contactor for shunting the converter cell, and a control unit provided with a power supply from the buffer capacitor, characterized in that the bypass contactor is made in in the form of a pair of counter-parallel connected thyristors, the control transitions of which are shunted in the opposite direction by diodes, while the control elec rows of said thyristor are connected through the contact impulse relay, the switching control unit.

This allows you to get the above technical result.

Utility Model Implementation

In FIG. 2 presents a diagram of the inventive module.

The module contains

at least one conversion cell 1 (transistor or thyristor, made according to the bridge or half-bridge circuit) with a buffer capacitor 2;

bypass contactor 3, designed to bypass cell 1 in case of failure;

a control unit 4 provided with a power supply 5 from the buffer capacitor 2.

Bypass contactor 3 is made in the form of a pair of counter-parallel connected thyristors 6 and 7. The control transitions of the thyristors 6 and 7 are shunted in the opposite direction by diodes 10 and 11, respectively, while the control electrodes 8 and 9 of these thyristors are connected through terminal 12 of the bistable pulse relay 13. As the relay 13, various types of commercially available low-power pulse relays can be used (for example, double-wound relays controlled by pulses or single-wound polarized relays, switched pulses opposite polarity) with a maximum switching voltage exceeding the amplitude of the operating voltage of the converter cell 1. Below, as an example, the use of a polarized pulse relay with one control winding is described. The control winding 14 of the relay 13 is connected to the corresponding output 15 of the control unit 4. The current pulse of one polarity in the winding 14 provides the closure of the contact 12, the other polarity - the opening of the contact 12.

The device operates as follows.

During normal operation of cell 1, terminal 12 of bistable relay 13 is in the open state shown in FIG. 2, and thyristors 6 and 7 are turned off.

In case of failure of cell 1 (controlled by means not shown in Fig. 2), the control unit 4 delivers from output 15 to winding 14 a short pulse of the corresponding polarity, which switches relay 13 with the closure of terminal 12. Moreover, depending on the current voltage polarity the terminals of cell 1 includes one of the thyristors 6 or 7, the control electrode of which receives current through a current-limiting resistor 16 and a diode 11 or 10, respectively. When the polarity of the voltage across cell 1 changes, another thyristor turns on in the same way. As a result, the conversion cell 1 is shunted by the contactor 3 at any voltage polarity.

As can be seen from the above, the control power of the contactor 3 is necessary only for a single formation of a short pulse in the control winding 14 of the low-power relay 13. As a result, there is no need for an independent power source to maintain the on state of the contactor 3 when it shunts cell 1 and the total power required for power supply module control circuits. Since this power is taken by the power supply unit 5 from the buffer capacitor 2, its capacity can be accordingly reduced.

Claims (1)

A multilevel voltage converter module comprising at least one converter cell with a buffer capacitor, a bypass contactor designed to bypass the converter cell, and a control unit provided with a power supply from the buffer capacitor, characterized in that the bypass contactor is made in the form of a counter-coupler thyristors connected in parallel, the control transitions of which are shunted in the opposite direction by diodes, while the control electrodes of these thyristors are connected Erez contact impulse relay, the switching control unit.

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