CN217789565U

CN217789565U - Soft power-on device of high-power three-level converter and converter

Info

Publication number: CN217789565U
Application number: CN202221129314.8U
Authority: CN
Inventors: 张艳清; 马逊; 杨鑫; 王海亮; 陈玫志; 窦艺朝; 杨光; 余笔超
Original assignee: Casic Feihang Technology Research Institute of Casia Haiying Mechanical and Electronic Research Institute
Current assignee: Casic Feihang Technology Research Institute of Casia Haiying Mechanical and Electronic Research Institute
Priority date: 2022-05-11
Filing date: 2022-05-11
Publication date: 2022-11-11
Anticipated expiration: 2032-05-11

Abstract

The utility model provides a soft power-on device of a high-power three-level converter and a converter, wherein the soft power-on device is connected in parallel to a direct current bus of the three-level converter and sequentially comprises a soft power-on contactor, a three-phase transformer, a single-phase rectifier bridge and a current-limiting resistor from an input end to an output end; one end of the soft power-on contactor is connected with a low-voltage power supply input, and the other end of the soft power-on contactor is connected with a three-phase transformer; two-phase output of the three-phase transformer is used as alternating current input of the single-phase rectifier bridge, and the other phase of the three-phase transformer is connected to the midpoint of the direct current bus; the direct current output by the single-phase rectifier bridge is respectively connected to the positive and negative terminals of the direct current bus of the three-level converter through a current-limiting resistor. The soft power-on device is connected in parallel to a direct current bus of the converter, and the mechanical contactor adopts a low-voltage device, so that the reliability of equipment is improved, and the replacement cost of a quick-wear part is reduced to a certain extent.

Description

High-power three-level converter soft power-on device and converter

Technical Field

The utility model belongs to the technical field of power electronic transform, concretely relates to soft power-on device of high-power three-level converter and converter.

Background

A large-capacity electrolytic capacitor or a thin-film capacitor is arranged in a direct-current link of a voltage source type high-voltage high-power converter (AC-DC-AC) and serves as a key device for supporting the bus voltage, and the capacitance value of the capacitor in the direct-current link is large in order to prevent the situation that the bus voltage fluctuates greatly in the loading process. When the converter is in a high-voltage electrifying process, the direct-current supporting capacitor hinders the change of the current voltage, so that pulse current similar to the short-circuit condition can be generated at the electrifying moment. The pulse current can cause large impact on power electronic devices (diodes or freewheeling diodes of IGBTs) of the rectifying unit, the service life of the power electronic devices is slightly influenced, and the permanent failure of the rectifying devices can be seriously caused, so that a soft power-on circuit or a device is very necessary to be added into the converter.

The current high-power converter soft power-on device generally adopts a high-voltage soft power-on scheme, namely soft power-on current-limiting resistors R1-R6 and bypass contactors KM1 and KM2 are added at the lower ports of high-voltage isolating switches QF1 and QF 2. When the converter is powered on, the direct current support capacitor is charged through the current-limiting resistor, and when the direct current bus voltage reaches a set threshold value, the current-limiting resistor is short-circuited by the bypass contactor, so that the voltage is increased to the rated bus voltage, as shown in fig. 1.

Because the high-voltage soft power-on scheme is to connect the soft power-on device in series to the power supply loop of the whole equipment, once the device fails, the normal operation of the equipment is disturbed. In addition, the devices of the scheme all need to adopt high-voltage devices, and the failure rate of the high-voltage devices, particularly the failure rate of the mechanical high-voltage contactor, is greater than that of the low-voltage devices, so that the replacement cost is higher.

Disclosure of Invention

The soft power-on device that goes up to the series connection that exists among the prior art inefficacy leads to the converter to become invalid, adopts technical problem such as the vulnerable high-voltage device, the utility model provides a soft power-on device and converter of high-power three-level converter, this soft power-on device connect in parallel on direct current bus, and mechanical type contactor adopts the low pressure device, improve equipment's reliability to reduce the replacement cost of vulnerable part at a certain degree.

The utility model provides a technical scheme as follows that above-mentioned technical problem adopted:

the utility model provides a soft power-on device of a high-power three-level converter, which is connected in parallel to a direct current bus of the three-level converter and comprises a soft power-on contactor, a three-phase transformer, a single-phase rectifier bridge and a current-limiting resistor from the input end to the output end in sequence; the soft power-on contactor is positioned between the low-voltage power supply input and the three-phase transformer; two phase outputs of the three-phase transformer are used as alternating current inputs of a single-phase rectifier bridge, and the other phase of the three-phase transformer is connected to the midpoint of a direct current bus; and the direct current output by the single-phase rectifier bridge is connected to the positive and negative terminals of a direct current bus of the three-level converter through a current-limiting resistor respectively.

The utility model also provides a soft power-on device of the high-power three-level converter, the soft power-on device is connected in parallel to the direct current bus of the three-level converter, and the soft power-on device sequentially comprises a soft power-on contactor, a current-limiting resistor, a three-phase transformer and a single-phase rectifier bridge from the input end to the output end; the soft power-on contactor and the current-limiting resistor are positioned between the low-voltage power supply input and the three-phase transformer; two phase outputs of the three-phase transformer are used as alternating current inputs of a single-phase rectifier bridge, and the other phase of the three-phase transformer is connected to the midpoint of a direct current bus; and the direct current output by the single-phase rectifier bridge is respectively connected to the positive and negative terminals of a direct current bus of the three-level converter.

Furthermore, a plurality of sets of soft power-on devices are connected in parallel to a direct-current bus of the three-level converter.

Further, the soft power-on contactor is a low-voltage mechanical contactor.

The utility model also provides a converter adopts aforementioned soft power-on device of high-power three-level converter.

Furthermore, a plurality of sets of soft power-on devices are connected to a direct-current bus of the converter in parallel.

The utility model has the advantages of compared with the prior art:

the utility model discloses with soft last electric installation parallelly connected to the direct current bus to the mechanical type contactor that will control its switch changes the low pressure device into by the high-pressure device. The utility model discloses soft power-on device adopts the H bridge rectification, can save the bridge arm. The utility model discloses soft last electric installation adopts the tripolar to support electric capacity to charge to three level converter direct currents, charges more stably, efficient. On one hand, the soft power-on device can be configured in a redundant mode (one working mode and one standby mode) when the converter is used as key equipment of a system, and the continuity of the soft power-on work of the converter is guaranteed; on the other hand, the reliability of the equipment can be improved by replacing the high-voltage mechanical switch with the low-voltage mechanical switch, and the replacement cost of the wearing parts is reduced to a certain degree.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

Fig. 1 is a schematic circuit diagram of a converter high-voltage soft power-on device in the prior art;

fig. 2 is a schematic structural diagram of a soft power-on device of a high-power three-level converter according to an embodiment of the present invention.

Detailed Description

The following is a detailed description of specific embodiments of the present invention. In the following description, for purposes of explanation and not limitation, specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details.

It should be noted that, in order to avoid obscuring the present invention with unnecessary details, only the device structures and/or processing steps closely related to the aspects of the present invention are shown in the drawings, and other details not closely related to the present invention are omitted.

The utility model provides a soft power-on device of three level converter of high-power, this soft power-on device connects in parallel to the DC bus of three level converter, includes soft power-on contactor KM1, three-phase transformer T1, single-phase rectifier bridge D1, current-limiting resistance R1, R2 from input to output in proper order; one end of the soft power-on contactor KM1 is connected with a low-voltage power supply input, and the other end of the soft power-on contactor KM1 is connected with a three-phase transformer T1; two-phase output of the three-phase transformer T1 is used as alternating current input of a single-phase rectifier bridge D1, and the other output is connected to the midpoint of a direct current bus; the direct current output by the single-phase rectifier bridge D1 is connected to the positive end and the negative end of a direct current bus of the three-level converter through current limiting resistors R1 and R2 respectively.

The utility model also provides a soft power-on device of high-power three-level converter, this soft power-on device connects in parallel to the dc bus of three-level converter, includes soft power-on contactor KM1, current-limiting resistor, three-phase transformer T1, single-phase rectifier bridge D1 from the input to the output in proper order; the soft upper electric contactor KM1 and the current-limiting resistor are connected between the low-voltage power supply input and the three-phase transformer T1; two-phase output of the three-phase transformer T1 is used as alternating current input of a single-phase rectifier bridge D1, and the other phase is connected to the midpoint of a direct current bus; the direct current output by the single-phase rectifier bridge D1 is respectively connected to the positive and negative terminals of a direct current bus of the three-level converter.

Any two phases of the three-phase transformer T1 are connected to the H-bridge rectifier, and the other phase is connected to the midpoint.

The utility model adopts a parallel mode, is decoupled with main power equipment, realizes the one-in-one-standby redundancy design and improves the system safety; the high-voltage mechanical switch is replaced by the low-voltage mechanical switch, the reliability of the system is improved, and the replacement cost of vulnerable parts is reduced; the bridge arm can be saved by adopting a low-voltage H rectifier bridge; one phase of the three-phase transformer is connected with the midpoint of the direct current bus, so that three-pole charging can be performed on the direct current support capacitor of the three-level converter, the charging is more stable, and the efficiency is high.

As shown in fig. 2, a low voltage soft power-up is performed prior to a high voltage power-up. Firstly, a soft power-on contactor KM1 is switched on, so that a low-voltage 380V power supply is connected to the soft power-on device, the input low voltage is boosted to the required voltage through a boosting transformer T1, and the voltage calculation formula is as follows:

transformer output voltage = upper bus voltage/1.414

Two phases of the three-phase transformer T1 are used as alternating current input of a single-phase rectifier bridge D1, the other phase of the three-phase transformer T1 is connected to the midpoint of a direct current bus, and direct current output by the single-phase rectifier bridge D1 is respectively connected to a positive direct current bus and a negative direct current bus of the three-level converter through current limiting resistors R1 and R2.

The soft power-on device shown in fig. 1 cannot work normally once the converter fails, and all the devices adopted in the scheme are high-voltage devices, and particularly, the high-voltage contactor belongs to a vulnerable part.

The utility model discloses parallelly connected to three level converter's direct current bus with soft last electric installation, do redundant configuration, be about to many sets of soft last electric installations parallelly connected on the generating line, even if one of them set became invalid, also can put into operation with redundant device, do very big improvement the reliability of overall system like this. In addition, the wearing parts of the soft power-on device are mechanical contactors, the service life of a high-voltage vacuum contactor is usually about 3-10 ten thousand times, and the service life of a low-voltage contactor is more than 100 ten thousand times. Consequently from the life angle, the utility model discloses a soft last electric installation reliability is higher, and maintenance and replacement cost are lower.

Features that are described and/or illustrated above with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

It should be emphasized that the term "comprises/comprising" when used herein, is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

The many features and advantages of these embodiments are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of these embodiments which fall within the true spirit and scope thereof. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the embodiments of the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope thereof.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

The detailed description of the present invention is the technology known to those skilled in the art.

Claims

1. A soft power-on device of a high-power three-level converter is characterized in that the soft power-on device is connected to a direct current bus of the three-level converter in parallel, and the soft power-on device sequentially comprises a soft power-on contactor, a three-phase transformer, a single-phase rectifier bridge and a current-limiting resistor from an input end to an output end; the soft upper electric contactor is positioned between the low-voltage power supply input and the three-phase transformer; two phase outputs of the three-phase transformer are used as alternating current inputs of a single-phase rectifier bridge, and the other phase of the three-phase transformer is connected to the midpoint of a direct current bus; and the direct current output by the single-phase rectifier bridge is respectively connected to the positive end and the negative end of a direct current bus of the three-level converter through a current-limiting resistor.

2. A soft power-on device of a high-power three-level converter is characterized in that the soft power-on device is connected to a direct-current bus of the three-level converter in parallel, and the soft power-on device sequentially comprises a soft power-on contactor, a current-limiting resistor, a three-phase transformer and a single-phase rectifier bridge from an input end to an output end; the soft power-on contactor and the current-limiting resistor are positioned between the low-voltage power supply input and the three-phase transformer; two phase outputs of the three-phase transformer are used as alternating current inputs of a single-phase rectifier bridge, and the other phase of the three-phase transformer is connected to the midpoint of a direct current bus; and the direct current output by the single-phase rectifier bridge is respectively connected to the positive and negative terminals of a direct current bus of the three-level converter.

3. The high-power three-level converter soft power-on device according to claim 1 or 2, wherein a plurality of sets of soft power-on devices are connected in parallel to a direct current bus of the three-level converter.

4. The soft power-on device of the high-power three-level converter according to claim 1 or 2, wherein the soft power-on contactor is a low-voltage mechanical contactor.

5. A converter, characterized in that the soft power-on device of the high-power three-level converter as claimed in claim 1 or 2 is used.

6. The converter according to claim 5, wherein a plurality of sets of the soft power-on devices are connected in parallel to a DC bus of the converter.