CN107769195A - Based on LC vibration forced commutation types mechanical switch, device and control method - Google Patents

Abstract

The present invention proposes a mechanical automatic switch circuit, device and control method based on LC oscillation forced commutation. The switch circuit includes a mechanical switch branch, an LC oscillation branch, a solid-state switch branch and an energy absorption branch. ; The mechanical switch branch, the LC oscillating branch, the solid-state switching branch and the energy absorbing branch are connected in parallel; wherein, the LC oscillating branch includes a gap switch and an LC oscillating circuit. The LC oscillation-based forced commutation type mechanical automatic switching circuit, device and controller thereof of the present invention have the characteristics of high reliability, low loss and fast switching.

Description

Forced commutation mechanical switch, device, and control method based on LC oscillation

technical field

The invention relates to the technical field of power electronics, in particular to an LC oscillation-based forced commutation type mechanical switching device, system and control method thereof.

Background technique

The power load of the modern power system has undergone tremendous changes. On the one hand, factors affecting power quality problems continue to grow, such as a large number of non-linear loads, large-scale impact electrical equipment, etc.; on the other hand, various complex, sophisticated, Electric equipment sensitive to power quality is also increasing, such as precision experimental instruments, some new medical equipment, semiconductor manufacturing and some production automatic control systems. The higher the requirements for power quality, the greater the direct harm caused by power quality problems to the power grid and power consumption system and the loss to human production and life.

Now, in order to solve the voltage drop fault, measures such as installing uninterruptible power supply in important occasions, automatic switching of mechanical switches, and equipment of self-contained generators are generally adopted. However, these methods have disadvantages such as high cost, low efficiency, slow speed, and small capacity, and cannot guarantee high-quality power supply. One of the most reliable and economical ways to solve the voltage drop and increase the power supply level is to use automatic transfer switches.

This kind of automatic transfer switch can automatically transfer the load circuit from one power source to another switching device to ensure the continuous operation of the load. However, this dual power switch still has the problems of slow switching speed and poor controllability. To this end, some researchers have proposed a hybrid automatic transfer switch (HATS, Hybrid Automatic Transfer Switching). As shown in Figure 1, it adopts a structure in which the solid-state switch IGBT is connected in parallel with the main mechanical switch. It consists of an IGBT and a rectifier bridge to form a solid-state switch commutation circuit, which operates before the mechanical switch, which improves the operation speed of the hybrid switch and Arc generation is limited. However, the reliability of this circuit is still low, and the power consumption is large and the switching speed is slow.

At present, the high-voltage and high-current switches that have been studied more mainly include gas gap switches, semiconductor switches, and trigger vacuum switches. Among them, the gas gap switch is simple and easy to operate, and has a large flow capacity, but its undervoltage ratio (the ratio of reliable trigger conduction voltage to self-breakdown voltage) is too high, that is, the operating voltage range is narrow, generally only 85% to 100%. Self-breakdown voltage is very inconvenient to use.

Contents of the invention

In order to solve the above technical problems, the present invention provides a mechanical automatic transfer switch circuit, device and control method based on LC oscillation forced commutation.

The invention provides a mechanical switch circuit based on LC oscillation forced commutation, which is characterized in that,

The switch circuit includes a mechanical switch branch, an LC oscillation branch, a solid state switch branch and an energy absorbing branch;

The mechanical switching branch, the LC oscillating branch, the solid state switching branch and the energy absorbing branch are connected in parallel; wherein,

The LC oscillation branch includes a gap switch and an LC oscillation circuit.

Further, the LC oscillating circuit includes an inductor and a capacitor connected in series, and the LC oscillating circuit is connected in series with the gap switch.

Further, the switch device also includes an energy absorbing branch.

Further, the energy absorption branch is connected in parallel with the mechanical switch branch.

Further, the energy absorption branch includes a lightning protection absorption system.

Further, the solid-state branch includes a solid-state switch or a plurality of solid-state switches connected in series.

The present invention also provides a switch circuit control method, which is applied to any one of the above switch circuits, and is characterized in that,

Controlling the opening of the mechanical switch in the mechanical switch branch, triggering the conduction of the gap switch in the gap switch branch, and then turning off the gap switch within a predetermined time.

Further, after the mechanical switch in the mechanical switch branch is controlled to open, after a preset delay, the gap switch in the gap switch branch is triggered to conduct, and/or

The step of turning off the gap switch again within a predetermined time is specifically turning off the gap switch when the mechanical switch opens and moves to a transient recovery voltage that the gap can withstand.

Further, the mechanical switch reaches an effective opening distance within the delay time.

The present invention also provides a switch circuit control method, which is applied to any one of the above switch circuits, and is characterized in that,

turning on the solid state switch;

closing the mechanical switch;

Open the solid state switch.

Further, the mechanical switch is closed while the solid-state switch is turned on, and/or

After the mechanical switch is closed, the solid state switch is opened when the current is diverted to the mechanical switch.

The present invention also provides an automatic transfer switch device, which is characterized in that the automatic transfer switch device includes a main transfer switch part and a standby transfer switch part, wherein,

The main switching part includes three mechanical switching circuits based on any LC oscillation forced commutation type as described above, which are respectively used in the A-phase, B-phase, and C-phase branches of the three-phase electricity;

The standby switch part includes three mechanical switch circuits based on LC oscillation forced commutation as described above, which are respectively used in the A-phase, B-phase, and C-phase branches of the three-phase electricity.

The present invention also provides a power switching protection system, characterized in that,

The power protection switching system includes:

Working power and backup power;

The automatic transfer switch device as described above, the main transfer switch part in the automatic transfer switch device is connected to the working power supply, and the standby transfer switch part is connected to the backup power supply;

A monitoring system for monitoring the working status of the working power supply and/or the backup power supply;

A control protection system controls the automatic transfer switch device to switch between the main transfer switch part and the standby transfer switch part.

Further, the monitoring system is also used to send the information of the working state to the control and protection system, and the control and protection system controls the automatic transfer switch device between the main transfer switch part and the backup switch according to the information. Switch between toggle switch widgets.

Further, the monitoring system also detects the disconnection state of the switch device, and feeds back the information of the disconnection state to the control and protection system.

The mechanical automatic switching circuit, device and control method based on LC oscillation forced commutation of the present invention have the characteristics of low loss and fast switching, simple structure and reliable performance.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 shows a schematic structural diagram of a hybrid automatic transfer switch in the prior art;

FIG. 2 shows a schematic structural diagram of a mechanical automatic transfer switch circuit based on LC oscillation forced commutation according to an embodiment of the present invention;

Fig. 3 shows a schematic structural diagram of a mechanical automatic transfer switch device based on LC oscillation forced commutation according to an embodiment of the present invention;

Fig. 4 shows a schematic structural diagram of a dual power supply redundant power supply system according to an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The switching device of the present invention adopts a mechanical automatic switching circuit based on LC oscillation forced commutation. The embodiment of the present invention takes the switch circuit as an example for illustration, but those skilled in the art should realize that, without departing from the basic inventive concept of the present invention, all devices that can realize circuit on and off, such as a switch and a circuit breaker, Switching circuits, components, parts, equipment, systems, etc. can all realize the present invention, and all of these belong to the protection scope of the present invention.

As shown in Figure 2, the mechanical automatic transfer switch circuit based on LC oscillation forced commutation mainly includes a mechanical switch branch, an LC oscillation branch, a solid-state switch branch and an energy absorption branch, the LC oscillation branch, The energy absorbing branch, the solid state switching branch and the mechanical switching branch are connected in parallel. Wherein, the mechanical switch branch mainly includes a mechanical switch. When the switch circuit is in normal operation, current flows through the mechanical switch to supply power to the load; the LC oscillation branch mainly includes a gap switch, an inductor L, and a capacitor C, and the gap switch, the inductor L, and the capacitor C in series; the solid state switch branch comprises one or more solid state switches, in the case of multiple solid state switches, the multiple solid state switches are connected in series. In Fig. 2, the branch where the solid-state switch is located is shown as a broken line, indicating that there may be one solid-state switch or multiple solid-state switches connected in series, but it does not mean that the branch where the solid-state switch is located is electrically disconnected. The energy absorbing branch mainly includes a lightning arrester. In the embodiment, a MOV (metal oxide varistor) zinc oxide lightning arrester is used, and the lightning arrester absorbs the residual energy generated during the opening and closing process of the mechanical switch, thereby realizing the protection of the mechanical switch. Switch overvoltage protection. The present invention uses the MOV zinc oxide arrester as an exemplary energy absorbing device, but is not limited to using the MOV zinc oxide arrester as the energy absorbing device. All energy absorbing circuits or systems capable of absorbing residual energy in the branch circuit can be used in the present invention.

When the switch circuit is in normal operation to establish a connection between the power supply and the load, the mechanical switch in the switch branch is in the closed state, the gap switch is in the open state, and the current to the load flows through the mechanical switch. switch.

The opening control process of the mechanical switch circuit based on LC oscillation forced commutation described in the embodiment is as follows: an opening command is issued to the mechanical switch in the mechanical switch branch of the switching circuit. The mechanical switch executes the opening action after receiving the opening command, and within a certain time t, the effective opening distance is reached after the contact opening distance reaches 2-3 millimeters (mm). After the mechanical switch has reached the effective opening distance, the gap switch in the gap switch branch is triggered to close, and the oscillating current generated by the oscillating capacitor C and oscillating inductance L pre-charged with reverse voltage is superimposed on the mechanical switch branch, The mechanical switch turns off the arc when it crosses zero. When the opening of the mechanical switch moves to the point where the gap can withstand the corresponding transient recovery voltage, the gap switch is controlled to be turned off, and the arrester absorbs the remaining energy of the system at the same time, and the opening process is completed.

The closing control process of the mechanical switching circuit based on LC oscillation forced commutation described in the embodiment is as follows: first turn on the solid-state switch, and then close the mechanical switch, or close the mechanical switch while turning on the solid-state switch, when the current transfer When reaching the mechanical switch, turn off the solid state switch.

The embodiment also provides a switch component, which adopts the above-mentioned LC oscillation-based forced commutation mechanical switch circuit. The switch component is used in a three-phase AC system, and the circuit of each phase adopts the above-mentioned forced commutation type mechanical switch circuit based on LC oscillation. As shown in Fig. 3, described switching part adopts above-mentioned automatic changeover switch circuit in A phase, B phase, C phase respectively: A phase, B phase, C phase in main switch part The three-phase lines of the switch are distinguished, A1, B1, and C1 represent A-phase, B-phase, and C-phase lines) all adopt the above-mentioned mechanical switch circuit based on LC oscillation forced commutation; Phase and phase C (in order to distinguish from the three-phase line of the main switch, A2, B2, and C2 represent phase A, phase B, and phase C) also adopt the above-mentioned forced commutation mechanical switch based on LC oscillation circuit.

As shown in FIG. 3 , the embodiment also provides an automatic transfer switch device, which includes two above-mentioned switch parts, one of which is a main transfer switch part and the other is a standby transfer switch part. During normal operation, the main switch part is turned on, so that the power supply can supply current to the load through the main switch part; the standby switch part is turned off. When a fault occurs and it is necessary to switch the power supply from the main diverter switch part to the standby diverter switch part, the main diverter switch part is disconnected through the above-mentioned opening control process, and the standby diverter switch part is turned on through the above-mentioned closing control process.

This embodiment uses a dual power supply redundant power supply system to illustrate the control and use of the above-mentioned LC oscillation-based forced commutation mechanical automatic transfer switch device. However, it should be clear that the LC oscillation forced commutation type mechanical automatic transfer switch device of the above-mentioned embodiment is not limited to the dual power supply redundant power supply system, the multi-power supply redundant power supply system and general power supply systems such as single power supply, can be used The switching power system and the like can use the LC oscillation-based forced commutation type mechanical automatic switching device described in the above embodiments.

FIG. 4 is a schematic structural diagram of a dual power supply redundant power supply system according to an embodiment of the present invention. The dual power supply system includes a power supply, a control protection system, an automatic transfer switch device, a load, and a monitoring system composed of monitoring components such as sensors, wherein the power supply includes two sets of power supplies, a working power supply and a backup power supply, and the automatic transfer switch device The main transfer switch part is connected with the working power supply, and the standby transfer switch part is connected with the standby power supply. In the dual power supply redundant power supply system, the main switch part on the working power branch and/or the standby switch part on the backup power branch can use the mechanical automatic switching based on LC oscillation forced commutation described in the above embodiment. switch parts. In this embodiment, both the switching switch on the working power supply branch and the switching switch on the standby power supply branch use the above-mentioned LC oscillation-based forced commutation type mechanical automatic switching component as an example for illustration.

In the normal power supply state of the dual power supply redundant power supply system, all the switch circuits (that is, the switch circuits on the A, B, and C phase lines) in the main switch parts of the working power supply branch in the automatic transfer switch device are in the In the closed state, the power of the working power supply is provided to the load through the transfer switch device; and all the switch circuits in the backup switch parts of the backup power supply branch in the automatic transfer switch device (that is, A, B, C phase The switching circuits on the line) are all in an off state, and the backup power supply does not provide power to the load.

The monitoring system continuously or periodically monitors the working status of the entire power supply system, such as abnormal conditions in the system: the sensor in the working power supply branch monitors the working status of the working power supply, and the sensor in the backup power supply branch monitors the working status of the backup power supply 1. The sensor in the load branch monitors the working state of the load.

When the monitoring system detects a failure of the working power supply or an excessive voltage drop, it sends a corresponding failure signal to the control and protection system. After the control and protection system receives the signal from the monitoring system indicating that the working power supply has failed, it judges that the working power supply has failed, and needs to switch the power supply from the working power supply to the standby power supply. At this time, the control unit in the control and protection system sends an opening command to the switching part of the working power supply, and sends a closing command to the switching part of the backup power supply, thereby controlling the switching part of the working power supply to disconnect, and controlling the switching part of the backup power supply. The diverter switch part of the power supply is closed to establish an electrical connection between the backup power source and the load, thereby providing power to the load through the backup power box.

During normal operation, all mechanical switches on phase A, phase B and phase C of the main diverter switch part are in the closed state, and the current on each phase line flows through the respective mechanical switches to provide power to the load. When the sensor detects that the working power supply fails, it sends an alarm message to the control and protection system. After receiving the alarm information, the control unit in the control and protection system sends an opening command to the mechanical switch of the main transfer switch part in the automatic transfer switch device. After the mechanical switch reaches the effective opening distance, the gap switches in each of the gap switch branches that trigger the main switch part are closed, and the oscillating current generated by the oscillating capacitor C and the oscillating inductance L pre-charged with reverse voltage is superimposed on the On the parallel mechanical switch branch, each mechanical switch is zero-crossing and extinguishes the arc. When the opening of the mechanical switch moves to the point where the gap can withstand the corresponding transient recovery voltage, the gap switch is controlled to be turned off, and the arrester absorbs the remaining energy of the system at the same time, and the opening process is completed.

At this time, the control unit in the control and protection system also sends a closing command to the backup transfer switch. After receiving the switch-on command sent by the control and protection system, the standby switch component first turns on the solid-state switch, and then closes the mechanical switch. It can also close the mechanical switch while turning on the solid-state switch. When the current is transferred to the mechanical switch , and then turn off the solid-state switch, so as to realize the closing of the diverter switch device in the backup power supply branch, so that the backup working power supply supplies power to the load.

In the dual power supply redundant power supply system, the process of switching from the standby power supply to the load to the working power supply to the load is the same as the process of switching from the working power supply to the load to the standby power supply to the load similar and will not be repeated here.

After the sensor in the load branch monitors that the load is faulty, it will send the detected fault information to the control and protection system. The control and protection system can close the switching components in the working power branch and the backup power branch according to the fault information, so as to disconnect any power supply from supplying power to the load.

The monitoring system simultaneously detects the switching on-off state, and feeds back state information to the control and protection system to ensure on-off and on-off.

The control and protection system also realizes the control of other contact switches or receives the status information of other contact switches according to the received information, and sends all the received information to the remote computer, and can receive information from the remote computer at the same time, such as controlling the relevant switching switch Open or closed information.

In the embodiment, three-phase alternating current is taken as an example for illustration, but those skilled in the art should realize that, without departing from the basic inventive concept of the present invention, the switching circuit, switching device, system and control method thereof of the present invention It is not limited to the three-phase alternating current for illustrative purposes in the specification, and the switching circuit, switching device, system and control method thereof of the present invention are applicable to systems including but not limited to direct current and alternating current.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (15)

1. A forced current-exchanging type mechanical switch circuit based on LC oscillation is characterized in that,

the switching circuit comprises a mechanical switching branch, an LC oscillation branch, a solid-state switching branch and an energy absorption branch;

the mechanical switching branch, the LC oscillating branch, the solid state switching branch and the energy absorbing branch are connected in parallel; wherein,

the LC oscillating branch comprises a gap switch and an LC oscillating circuit.

2. The switching circuit of claim 1,

the LC oscillating circuit comprises an inductor and a capacitor which are connected in series, and the LC oscillating circuit is connected with the gap switch in series.

3. The switching circuit according to claim 1 or 2,

the switching device further comprises an energy absorbing branch.

4. The switching circuit of claim 3,

the energy absorption branch is connected in parallel with the mechanical switch branch.

5. The switching circuit of claim 4,

the energy absorption branch comprises a lightning arrester.

6. The switching circuit of claim 1,

the solid-state branch comprises one solid-state switch or a plurality of solid-state switches connected in series.

7. A switching circuit control method applied to the switching circuit according to any one of claims 1 to 6,

and controlling the mechanical switch in the mechanical switch branch to open, triggering and conducting the gap switch in the gap switch branch, and switching off the gap switch within preset time.

8. The switching circuit control method according to claim 7,

after the mechanical switch in the mechanical switch branch is controlled to be switched off and a preset time delay is carried out, the gap switch in the gap switch branch is triggered to be switched on, and/or

Specifically, the disconnecting of the gap switch within the predetermined time is to disconnect the gap switch when the mechanical switch is switched off and moves to a transient recovery voltage that can be borne by the gap.

9. The switching circuit control method according to claim 8,

and the mechanical switch reaches an effective opening distance within the delay time.

10. A switching circuit control method applied to the switching circuit according to any one of claims 1 to 6,

turning on the solid state switch;

closing the mechanical switch;

the solid state switch is opened.

11. The switching circuit control method according to claim 10,

closing the mechanical switch while conducting the solid state switch, and/or

After closing the mechanical switch, the solid-state switch is opened again when current is transferred to the mechanical switch.

12. An automatic transfer switch device characterized by comprising a main transfer switch part and a backup transfer switch part, wherein,

the main change-over switch component comprises three forced current change type mechanical switch circuits based on LC oscillation according to any one of claims 1-6, wherein the forced current change type mechanical switch circuits are respectively used in A-phase, B-phase and C-phase branches of three-phase electricity;

the switching component comprises three forced current change type mechanical switching circuits based on LC oscillation according to any one of claims 1-6, wherein the forced current change type mechanical switching circuits are respectively used in A-phase, B-phase and C-phase branches of three-phase power.

13. A power switching protection system is characterized in that,

the power protection switching system includes:

a working power supply and a standby power supply;

the automatic transfer switching apparatus of claim 9, wherein the main transfer switching means is connected to an operating power supply and the backup transfer switching means is connected to a backup power supply;

the monitoring system is used for monitoring the working state of the working power supply and/or the standby power supply;

and the control protection system controls the automatic change-over switch device to switch between the main change-over switch component and the standby change-over switch component.

14. The power switching protection system of claim 12,

the monitoring system is also used for sending the information of the working state to the control protection system, and the control protection system controls the automatic change-over switch device to be switched between the main change-over switch component and the standby change-over switch component according to the information.

15. The power switching protection system of claim 13 or 14,

the monitoring system also detects the on-off state of the automatic transfer switch device and feeds back the information of the on-off state to the control protection system.