Automatic switching device of standby frequency converter

Abstract

The utility model belongs to the technical field of automatic switching, and particularly relates to an automatic switching device for a standby frequency converter, which enables the standby frequency converter to be in a hot standby state by directly connecting the standby frequency converter to a high-voltage power supply, is helpful to realize that the standby frequency converter does not need to be preheated when a main frequency converter or a secondary frequency converter breaks down, and is convenient to use. The standby frequency converter can be quickly switched to work only by automatically disconnecting a corresponding contactor, non-planned shutdown is avoided, personal safety is guaranteed through automatic switching, in addition, the standby frequency converter searches for the residual voltage frequency of the first motor through the galloping function, the standby frequency converter can be automatically accelerated to the previous frequency after switching, and the working efficiency of the standby frequency converter is improved. Not only is the working efficiency improved, but also the non-planned shutdown is further ensured.

Description

Technical Field

[0001] The utility model belongs to the technical field of detection, and particularly relates to an automatic switching device for a standby frequency converter. Background Technique

[0002] With the increasing popularity of automated production, the requirements for production continuity are also getting higher and higher. The application of frequency converters is becoming more and more extensive. However, in important places, once the frequency converter fails, it will lead to production accidents or even safety accidents. In such cases, the online automatic switching method of low-voltage frequency converters is particularly important.

[0003] Currently, the used standby frequency converter switching device, such as Figure 1 shown in the figure, where QF1 and QF2 are user trolley switches, QS1~QS4 are single-pole double-throw knife switches, and KM1 and KM2 are vacuum circuit breakers. QS1 and QS2 are interlocked; QS3 and QS4 are interlocked. KM1 and KM2 are interlocked. QS1 and QS3 are interlocked, QS2 and QS4 are interlocked, KM1 and QS1 are interlocked, and KM2 and QS2 are interlocked.

[0004] When in use, if one of the original frequency converters fails, taking the original frequency converter of motor A as an example: after determining that QF1 is in the off position, close the isolating switch QS1 to position a, then throw the isolating switch QS3 to position a, close KM1, and then send a running command. When the standby frequency converter is fully charged, automatically close QF1, and the frequency converter drives motor A to run in frequency conversion. It can be seen that this frequency converter switching device not only requires manual switching operations to put the standby frequency converter into use, which is not conducive to personal safety, but also switches after the motor stops, and it is impossible to avoid unplanned stops due to frequency converter failures. Summary of the Invention

[0005] In order to solve the technical problems existing in the above background technique, the utility model provides an automatic switching device for a standby frequency converter, aiming to be able to automatically put the standby frequency converter into operation when the frequency converter fails, prevent equipment shutdown, not only ensure the personal safety of electrical operators, but also avoid unplanned stops due to frequency converter failures.

[0006] In order to achieve the above technical solution, the utility model provides an automatic switching device for a standby frequency converter, including: a first trolley switch QF1, a second trolley switch QF2, and a third trolley switch QF3;

[0007] The input end of the first trolley switch QF1 is connected to a first high-voltage power supply, the output end of the first switch trolley QF1 is connected to the main frequency converter, the main frequency converter is connected to the first motor through a first contactor KM1 and a first switch QS1; the main frequency converter is also grounded through a first live-line indicator DXN1;

[0008] The input end of the third switch trolley QF3 is connected to the first high-voltage power supply, and the output end of the third switch trolley QF3 is connected to the standby frequency converter; the standby frequency converter is connected to the first motor through the third switch QS3 and the third contactor KM3; the standby frequency converter is connected to the second motor through the fourth switch QS4 and the fourth contactor KM4; the standby frequency converter is grounded through the fifth live display DXN5; the standby frequency converter is connected to the first mutual inductor PT1 and the second mutual inductor PT2 through the first fuse FU1, the second fuse FU2 and the third fuse FU3;

[0009] The input end of the second switch trolley QF2 is connected to the second high-voltage power supply, and the output end of the second switch trolley QF2 is connected to the secondary frequency converter. The secondary frequency converter is connected to the second motor through the contactor KM2 and the second switch QS2; the secondary frequency converter is also grounded through the second live display DXN2;

[0010] It is grounded through the third live display DXN3 between the third contactor KM3 and the third switch QS3;

[0011] It is also grounded through the fourth live display DXN4 between the fourth contactor KM4 and the fourth switch QS4.

[0012] Furthermore, the device further includes a control module, which is connected to the first contactor KM1, the second contactor KM2, the third contactor KM3, the fourth contactor KM4, the standby frequency converter, the main frequency converter, the secondary frequency converter, and is connected to the first switch trolley QF1, the second switch trolley QF2 and the third switch trolley QF3.

[0013] Furthermore, the first contactor KM1, the second contactor KM2, the third contactor KM3 and the fourth contactor KM4 all adopt vacuum contactors.

[0014] Furthermore, the main frequency converter, the secondary frequency converter and the standby frequency converter all adopt IGBT intelligent drive frequency converters.

[0015] Furthermore, the first contactor KM1 and the third contactor KM3 are interlocked; the second contactor KM2 and the fourth contactor KM4 are interlocked; the third contactor KM3 and the fourth contactor KM4 are interlocked.

[0016] Furthermore, the control module adopts a decentralized control module.

[0017] Furthermore, the first high-voltage power supply and the second high-voltage power supply are output high-voltage cables in different sections.

[0018] The beneficial effects of the present utility model are:

[0019] By directly connecting the standby frequency converter to the high-voltage power supply, the standby frequency converter can be in a hot standby state, which helps to achieve that when the main frequency converter or the secondary frequency converter fails, there is no need to preheat the standby frequency converter. Only by automatically disconnecting the corresponding contactor can it quickly switch to the standby frequency converter for operation, avoiding unplanned shutdowns. Moreover, through automatic switching, it also helps to ensure personal safety.

[0020] In addition, by enabling the standby frequency converter to search for the residual voltage frequency of the first motor using the coasting function, it can automatically accelerate to the previous frequency after switching, which not only helps to improve work efficiency but also further ensures against unplanned shutdowns.

[0021] Advantages of additional aspects of the present utility model will be partly given in the following description, partly will become apparent from the following description, or will be understood through the practice of the present utility model. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings forming a part of this specification are used to provide a further understanding of the present utility model. The schematic embodiments and descriptions thereof of the present utility model are used to explain the present utility model and do not constitute an improper limitation to the present utility model.

[0023] Figure 1 It is a schematic structural diagram of the existing automatic switching device for the standby frequency converter of the present utility model.

[0024] Figure 2 It is a schematic structural diagram of the automatic switching device for the standby frequency converter of the present utility model.

[0025] Figure 3 It is an electrical schematic diagram of the automatic switching device for the standby frequency converter of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The present utility model will be further described below in conjunction with the drawings and embodiments.

[0027] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanations of the present utility model. Unless otherwise specified, each technical and scientific term used in this embodiment has the same meaning as commonly understood by those of ordinary skill in the technical field to which the present utility model belongs.

[0028] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present utility model. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0029] In the present utility model, terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only relational terms determined for the convenience of describing the structural relationships of various components or elements of the present utility model, and do not specifically refer to any component or element in the present utility model, and should not be construed as a limitation to the present utility model.

[0030] In the present utility model, terms such as "fixed connection", "connected", "connected to" should be understood in a broad sense, which may mean a fixed connection, an integral connection or a detachable connection; it may be directly connected or indirectly connected through an intermediate medium. For relevant scientific research or maintenance personnel in this field, the specific meanings of the above terms in the present utility model can be determined according to specific circumstances, and should not be construed as a limitation to the present utility model.

[0031] Embodiment 1:

[0032] As Figure 2 shown, this embodiment provides an automatic switching device for a standby frequency converter. As Figure 1 shown, the device includes: a first trolley switch QF1, a second trolley switch QF2 and a third trolley switch QF3;

[0033] A first high-voltage power supply 6 is connected to the main frequency converter 1 through the first trolley switch QF1. The main frequency converter 1 is connected to the first motor 4 through the first contactor KM1 and the first switch QS1; the main frequency converter 1 is also grounded through the first live display DXN1.

[0034] The first high-voltage power supply 6 is also connected to the standby frequency converter 2 through the third trolley switch QF3; the standby frequency converter 2 is connected to the first motor 4 through the third switch QS3 and the third contactor KM3; the standby frequency converter 2 is connected to the second motor 5 through the fourth switch QS4 and the fourth contactor KM4; the standby frequency converter 2 is grounded through the fifth live display DXN5; the standby frequency converter 2 is connected to the first mutual inductor PT1 and the second mutual inductor PT2 through the first fuse FU1, the second fuse FU2 and the third fuse FU3.

[0035] A second high-voltage power supply 7 is connected to the secondary frequency converter 3 through the second trolley switch QF2. The secondary frequency converter 3 is connected to the second motor 5 through the contactor KM2 and the second switch QS2; the secondary frequency converter 3 is also grounded through the second live display DXN2.

[0036] It is grounded through the third live display DXN3 between the third contactor KM3 and the third switch QS3.

[0037] It is also grounded through the fourth live display DXN4 between the fourth contactor KM4 and the fourth switch QS4.

[0038] Among them, the first contactor KM1, the second contactor KM2, the third contactor KM3, and the fourth contactor KM4 are all vacuum contactors. The main frequency converter 1, the secondary frequency converter 3, and the standby frequency converter 2 all adopt IGBT intelligent drive frequency converters. The first switch QS1, the second switch QS2, the third switch QS3, and the fourth switch QS4 are single-pole double-throw knife switches.

[0039] Furthermore, as Figure 3 shown, the device further includes a control module 8, and the control module 8 is connected to the first contactor KM1, the second contactor KM2, the third contactor KM3, the fourth contactor KM4, the standby frequency converter 2, the main frequency converter 1, the secondary frequency converter 3, the first trolley switch QF1, the second trolley switch QF2, and the third trolley switch QF3.

[0040] In this embodiment, where:

[0041] The first contactor KM1 and the third contactor KM3 are interlocked, that is, after the first contactor KM1 is closed, the third contactor KM3 cannot be closed; after the third contactor KM3 is closed, KM1 cannot be closed.

[0042] The second contactor KM2 and the fourth contactor KM4 are interlocked, that is, after the second contactor KM2 is closed, the fourth contactor KM4 cannot be closed; after the fourth contactor KM4 is closed, the second contactor KM2 cannot be closed.

[0043] The third contactor KM3 and the fourth contactor KM4 are interlocked, that is, after the third contactor KM3 is closed, the fourth contactor KM4 cannot be closed; after the fourth contactor KM4 is closed, the third contactor KM3 cannot be closed.

[0044] In this embodiment, the automatic switching performs the following steps:

[0045] If the main frequency converter fails (for example, when the DCS detects that the frequency of the main frequency converter is unstable), causing the first motor to fail to operate normally, the DCS controls the first contactor KM1 to disconnect, and sends a running instruction for the first motor to the standby frequency converter, and at the same time controls the third contactor KM3 to automatically close. After the third contactor KM3 is closed, the standby frequency converter uses the coasting function (wherein, the coasting function of the frequency converter is well known to those skilled in the art and will not be elaborated here again) to search for the residual voltage frequency of the first motor, and the standby frequency converter drives the first motor to operate according to the searched residual voltage frequency.

[0046] If the secondary frequency converter fails (for example, when the DCS detects that the frequency of the main frequency converter is unstable), causing the second motor to malfunction, the distributed control system (DCS) controls the second contactor KM2 to open and sends a command to run the second motor to the standby frequency converter. At the same time, it controls the fourth contactor KM3 to automatically close. After the fourth contactor KM3 closes, the standby frequency converter uses the coasting function (wherein, the coasting function of the frequency converter is well-known to those skilled in the art and will not be elaborated here again) to search for the residual voltage frequency of the second motor, and the standby frequency converter drives the second motor to run by outputting the corresponding frequency according to the searched residual voltage frequency.

[0047] If the standby frequency converter needs to stop, the following operation process is executed: (for example, when the DCS detects that the operating frequency of the faulty frequency converter is normal), the DCS sends a stop command to the standby frequency converter. Based on the received stop instruction, the standby frequency converter automatically reduces the operating frequency and controls the third contactor or the fourth contactor to automatically open after detecting that the frequency of the standby frequency converter has dropped to 0 Hz, and it is in the hot standby state again.

[0048] It should be noted that, in order to achieve automatic switching in this embodiment, the standby frequency converter is always in the hot standby state. The execution steps for keeping the standby frequency converter in the hot standby state are as follows:

[0049] After determining that the third trolley switch QF3, the third contactor KM3, and the fourth contactor KM4 are in the open state, close the third switch QS3 and the fourth switch QS4, and send a charging command to the standby frequency converter through the distributed control system (DCS) to make the frequency converter start charging (wherein, the charging power supply of the frequency converter is an external low-voltage detection power supply). After the DCS detects that the frequency converter has completed charging, it controls the third trolley switch QF3 to automatically close, making the standby frequency converter in the hot standby state.

[0050] In this embodiment, by directly connecting the standby frequency converter to the high-voltage power supply, the standby frequency converter can be in the hot standby state, which helps to achieve that when the main frequency converter or the secondary frequency converter fails, there is no need to preheat the standby frequency converter. Only by automatically disconnecting the corresponding contactor, it can quickly switch to the standby frequency converter for work, avoiding unplanned shutdowns. Moreover, through automatic switching, it also helps to ensure personal safety.

[0051] In addition, by enabling the standby frequency converter to use the coasting function to search for the residual voltage frequency of the first motor, it can automatically accelerate to the previous frequency after switching, which not only helps to improve work efficiency but also further ensures against unplanned shutdowns.

[0052] In this specification, for the same or similar parts among various embodiments, reference can be made to each other. In particular, for the terminal embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and for the relevant parts, reference can be made to the descriptions in the method embodiments.

[0053] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0054] The above are only the preferred embodiments of the present utility model and are not intended to limit the present utility model. For those skilled in the art, the present utility model can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. An automatic switching device for standby frequency converters, characterized in that, include: First trolley switch QF1, second trolley switch QF2 and third trolley switch QF3; The input end of the first trolley switch QF1 is connected to the first high-voltage power supply, and the output end of the first switch trolley QF1 is connected to the main inverter, which is connected to the first motor through the first contactor KM1 and the first switch QS1; the main inverter is also grounded through the first live indicator DXN1; The input end of the third trolley switch QF3 is connected to the first high-voltage power supply, and the output end of the third switch trolley QF3 is connected to the standby inverter; the standby inverter is connected to the first motor through the third switch QS3 and the third contactor KM3; the standby inverter is connected to the second motor through the fourth switch QS4 and the fourth contactor KM4; the standby inverter is grounded through the fifth power indicator DXN5; the standby inverter is connected to the first mutual inductance coil PT1 and the second mutual inductance coil PT2 through the first fuse FU1, the second fuse FU2 and the third fuse FU3; The input end of the second trolley switch QF2 is connected to the second high-voltage power supply, and the output end of the second switch trolley QF2 is connected to the secondary inverter, which is connected to the second motor through the contactor KM2 and the second switch QS2; the secondary inverter is also grounded through the second live indicator DXN2; Between the third contactor KM3 and the third switch QS3, grounding is provided via the third live indicator DXN3; A fourth charge indicator DXN4 is also connected to ground between the fourth contactor KM4 and the fourth switch QS4.

2. The automatic switching device for standby frequency converter according to claim 1, characterized in that: The device also includes a control module, which is connected to the first contactor KM1, the second contactor KM2, the third contactor KM3, the fourth contactor KM4, the standby inverter, the main inverter, the secondary inverter, the first trolley switch QF1, the second trolley switch QF2 and the third trolley switch QF3.

3. The automatic switching device for standby frequency converters according to claim 1, characterized in that, The first contactor KM1 , the second contactor KM2 , the third contactor KM3 and the fourth contactor KM4 are all vacuum contactors.

4. The automatic switching device for a standby frequency converter according to claim 1, characterized in that: The main frequency converter, secondary frequency converter and standby frequency converter all adopt IGBT intelligent drive frequency converter.

5. The automatic switching device for standby frequency converters according to claim 1, characterized in that, The first contactor KM1 and the third contactor KM3 are interlocked; the second contactor KM2 and the fourth contactor KM4 are interlocked; The third contactor KM3 and the fourth contactor KM4 are interlocked.

6. The automatic switching device for standby frequency converters according to claim 2, wherein The control module adopts a decentralized control module.

7. The automatic switching device for standby frequency converters according to claim 1, characterized in that, The first high-voltage power supply and the second high-voltage power supply are output high-voltage cables located in different sections.

Images