CN107769195B - Forced commutation mechanical switch, device, and control method based on LC oscillation - Google Patents

Abstract

The invention provides a forced flow conversion type mechanical automatic switching circuit based on LC oscillation, a device and a control method thereof, wherein 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; the LC oscillation branch comprises a gap switch and an LC oscillation circuit. The forced flow-changing type mechanical automatic change-over switch circuit based on LC oscillation, the forced flow-changing type mechanical automatic change-over device based on LC oscillation and the control method thereof have the characteristics of high reliability, low loss and quick change-over.

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 a forced commutation mechanical switch device, system and control method based on LC oscillation.

Background technique

The power load of modern power systems has undergone tremendous changes. On the one hand, factors that affect power quality problems continue to increase, such as a large number of nonlinear loads and the investment of large-scale impact electrical equipment; on the other hand, various complex, sophisticated, Electrical 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 the power system and the greater the loss to human production and life.

Now, in order to solve the voltage sag fault, measures such as installing uninterruptible power supply, self-switching mechanical switch, and equipping self-contained generator are widely adopted in important occasions. 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 address voltage dips and increase power levels is to use automatic transfer switches.

This automatic transfer switch can realize the switching device that automatically transfers the load circuit from one power source to another power source 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 TransferSwitching). As shown in Figure 1, it adopts a structure in which the solid-state switching IGBT is connected in parallel with the main mechanical switch. The solid-state switching commutation circuit is composed of IGBTs and rectifier bridges, which act before the mechanical switch action, which improves the action speed of the hybrid switch. The arc generation is limited. However, the reliability of such circuits is still low, and the power consumption is high and the switching speed is slow.

At present, the most studied high-voltage high-current switches 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 current capacity, but its undervoltage ratio (the ratio of reliable trigger on-voltage to self-breakdown voltage) is too high, that is, the operating voltage range is narrow, generally only 85% ~ 100% Self-breakdown voltage is very inconvenient to use.

SUMMARY OF THE INVENTION

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

The invention provides a forced commutation mechanical switch circuit based on LC oscillation, 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 absorption branch;

The mechanical switch branch, the LC oscillation branch, the solid state switch branch, and the energy absorption 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 further includes an energy absorption 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, characterized in that:

The mechanical switch in the mechanical switch branch is controlled to open, the gap switch in the gap switch branch is triggered to be turned on, and the gap switch is turned off 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 be turned on, and/or

The disconnecting the gap switch again within a predetermined time is specifically, disconnecting the gap switch when the mechanical switch is opened and moves to a transient recovery voltage that the gap can withstand.

Further, the mechanical switch reaches an effective 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, 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 closing the mechanical switch, the solid state switch is opened when the current is transferred to the mechanical switch.

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

The main switch component includes any one of the above-mentioned forced commutation mechanical switch circuits based on LC oscillation, which are respectively used in the A-phase, B-phase, and C-phase branches of the three-phase electricity;

The standby switch component includes any one of the above-mentioned LC oscillation-based forced commutation type mechanical switch circuits, 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, which is characterized in that:

The power protection switching system includes:

Working power and backup power;

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

A monitoring system for monitoring the working state of the working power source and/or the backup power source;

A protection system is controlled to control the automatic transfer switch device to switch between the main transfer switch part and the backup transfer switch part.

Further, the monitoring system is further configured 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 in the main transfer switch component and the backup switch according to the information. Toggle switch between components.

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

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

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the accompanying 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. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

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

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

3 shows a schematic structural diagram of a forced commutation type mechanical automatic switch device based on LC oscillation 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 purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The switch device of the present invention adopts a forced commutation type mechanical automatic switch circuit based on LC oscillation. The embodiments of the present invention take a switch circuit as an example for illustrative description, but those skilled in the art should realize that, without departing from the basic inventive concept of the present invention, all devices such as a switch, circuit breaker, etc., which can realize circuit on-off Switching circuits, elements, components, equipment, systems, etc. can all implement the present invention, and these all fall within the protection scope of the present invention.

As shown in Figure 2, the LC oscillation-based forced commutation type mechanical automatic switch circuit 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 absorption branch, the solid state switch branch and the mechanical switch branch are connected in parallel. Wherein, the mechanical switch branch mainly includes a mechanical switch. When the switch circuit operates normally, the current flows through the mechanical switch to supply power to the load; the LC oscillation branch mainly includes a gap switch, an inductance L, and a capacitor C, and the gap switch, the inductance L, and the capacitor C is connected in series; the solid state switch branch includes one or more solid state switches, and 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 broken to indicate 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 absorption branch mainly includes a surge arrester. In the embodiment, a MOV (metal oxide varistor) zinc oxide surge arrester is used. The surge arrester absorbs the residual energy generated during the opening and closing of the mechanical switch, thereby realizing the mechanical Overvoltage protection of the switch. 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 that can absorb the remaining energy in the branch can be used in the present invention.

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

The opening control process of the forced commutation mechanical switch circuit based on LC oscillation described in the embodiment is as follows: an opening command is issued to the mechanical switch in the branch of the mechanical switch in the switch circuit. The mechanical switch performs the opening action after receiving the opening command, and within a certain time t, after the contact opening distance reaches 2-3 millimeters (mm), the effective opening distance is reached. After the mechanical switch has reached the effective distance, the gap switch in the gap switch branch is triggered to close, and the oscillating current generated by the oscillating capacitor C and the oscillating inductance L precharged with the reverse voltage is superimposed on the mechanical switch branch. The mechanical switch zero-crosses the arc. When the mechanical switch moves to the point where the gap can withstand the corresponding transient recovery voltage, the gap switch is controlled to be disconnected, 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 forced commutation mechanical switch circuit based on LC oscillation described in the embodiment is as follows: the solid state switch is turned on first, and then the mechanical switch is closed, or the mechanical switch can be closed while the solid state switch is turned on. When the mechanical switch is reached, disconnect the solid state switch.

The embodiment also provides a switch component, which adopts the above-mentioned LC oscillation-based forced commutation type mechanical switch circuit. The switch component is used in a three-phase alternating current 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 , the switch components respectively adopt the above-mentioned automatic transfer switch circuit in the A-phase, B-phase, and C-phase: A-phase, B-phase, and C-phase in the main switch-over switch component (in the figure, in order to switch with the standby switch) 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 LC oscillation forced commutation mechanical switch circuit; Phase and C-phase (in order to distinguish from the three-phase line of the main switch in the figure, A2, B2, C2 represent A-phase, B-phase, C-phase line) also use the above-mentioned LC oscillation forced commutation type mechanical switch circuit.

As shown in FIG. 3 , the embodiment further provides an automatic transfer switch device, the automatic transfer switch device includes two above-mentioned switch components, one of which is a main switch component and the other is a backup switch component. During normal operation, the main switch part is turned on, so that the power supply provides current to the load through the main switch part; the backup switch part is disconnected. When a fault occurs and the power supply needs to be switched from the main switch part to the backup switch part, the main switch part is disconnected through the above-mentioned opening control process, and the standby switch part is turned on through the above-mentioned closing control process.

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

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 and protection system, an automatic switching 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 switching switch device is composed of two sets of power supplies. The main switch part is connected with the working power supply, and the backup switch part is connected with the backup power supply. In the dual power supply redundant power supply system, the main switch components on the working power supply branch and/or the standby switch components on the standby power supply branch can use the LC oscillation-based forced commutation type mechanical automatic switching described in the above embodiment. switch parts. This embodiment is exemplified by using the above-mentioned LC oscillation-based forced commutation type mechanical automatic switch component as an example for the switch on the working power supply branch and the switch on the standby power supply branch.

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 component of the working power supply branch in the automatic transfer switch device are in In the closed state, the power of the working power supply is provided to the load through the transfer switch device; and all switch circuits (that is, phases A, B, and C) in the standby transfer switch components of the standby power supply branch in the automatic transfer switch device switch circuits on the line) are in an open state, and the backup power supply does not provide power to the load.

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

The monitoring system sends a corresponding fault signal to the control and protection system when it detects that the working power supply is faulty or the voltage drop is too large. After receiving the signal indicating the failure of the working power supply from the monitoring system, the control and protection system judges that the working power supply is faulty 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 protection system sends an opening command to the switch part of the working power supply and a closing command to the switch part of the standby power supply, thereby controlling the switch part of the working power supply to disconnect and control the standby power supply. The transfer switch component of the power source is closed to establish an electrical connection between the backup power source and the load, thereby providing power through the backup power box load.

During normal operation, all mechanical switches on the A-phase, B-phase and C-phase lines in the main transfer switch unit are closed, and the current on each phase line flows through the respective mechanical switches to provide power to the load. When the sensor detects the failure of the working power supply, it sends alarm information to the control and protection system. After receiving the alarm information, the control unit in the control and protection system issues an opening command to the mechanical switch of the main diverter switch component in the automatic diverter switch device. After the mechanical switch reaches an effective distance, the gap switches in each of the gap switch branches of the main switch component are triggered to close, and the oscillating current generated by the oscillating capacitor C and oscillating inductance L precharged with reverse voltage is superimposed to On the branches of the mechanical switches connected in parallel, each of the mechanical switches crosses zero and extinguishes the arc. When the mechanical switch moves to the point where the gap can withstand the corresponding transient recovery voltage, the gap switch is controlled to be disconnected, 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 protection system also issues a closing command to the standby diverter switch. After receiving the closing command sent by the control and protection system, the standby diverter switch component turns on the solid state switch first, and then closes the mechanical switch, or closes the mechanical switch while turning on the solid state switch. When the current is transferred to the mechanical switch , and then disconnect the solid-state switch, thereby realizing the closing of the switch device in the standby power supply branch, so that the standby working power supply supplies power to the load.

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

After monitoring the failure of the load, the sensor in the load branch will send the monitored failure information to the control and protection system. The control and protection system can turn off the switch components in the working power supply branch and the backup power supply branch according to the fault information, so as to disconnect any power supply to supply power to the load.

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

The control protection system also realizes the control of other tie switches or receives the status information of other tie switches according to the received information, and sends all the received information to the remote computer. Open or closed information.

In the embodiments, three-phase alternating current is taken as an example for illustration, but those skilled in the art should realize that the switch circuit, switch device, system and control method thereof of the present invention will not deviate from the basic inventive concept of the present invention. Not limited to the three-phase alternating current for the purpose of illustration in the specification, 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.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Thus, provided that these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims (10)

1. a forced commutation type mechanical switch circuit based on LC oscillation, is characterized in that, 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 oscillation branch, the solid state switch branch, and the energy absorption branch are connected in parallel; wherein, The LC oscillation branch includes a gap switch and an LC oscillation circuit; 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; The mechanical switch branch includes a mechanical switch; The solid-state switch branch includes a plurality of series-connected solid-state switches; the energy absorption branch includes a lightning arrester; The forced commutation mechanical switch circuit based on LC oscillation is used in the opening process: The mechanical switch performs the opening action after receiving the opening command, and within a certain time t, after the contact opening distance reaches 2-3 mm, the effective opening distance is reached; After the mechanical switch has reached an effective distance, the gap switch in the LC oscillating branch is triggered to close, and the oscillating current generated by the capacitor and inductance precharged with the reverse voltage is superimposed on the mechanical switching branch. Zero-cross arc extinguishing; When the mechanical switch moves to the point where the gap can withstand the corresponding transient recovery voltage, the gap switch is controlled to be disconnected, and the arrester absorbs the remaining energy of the system; The forced commutation mechanical switch circuit based on LC oscillation is used in the closing control process: the solid state switch is turned on first, then the mechanical switch is closed, and when the current is transferred to the mechanical switch, the solid state switch is turned off. 2. A switching circuit control method, applied in the switching circuit as claimed in claim 1, characterized in that, The mechanical switch in the mechanical switch branch is controlled to open, the gap switch in the LC oscillation branch is triggered to be turned on, and the gap switch is turned off within a predetermined time. 3. The switching circuit control method according to claim 2, wherein, After the mechanical switch in the mechanical switch branch is controlled to open, after a preset delay, the gap switch in the LC oscillation branch is triggered to be turned on, and/or The disconnecting the gap switch again within a predetermined time is specifically, disconnecting the gap switch when the mechanical switch is opened and moves to a transient recovery voltage that the gap can withstand. 4. The switching circuit control method according to claim 3, wherein, The mechanical switch reaches an effective distance within the delay time. 5. A switching circuit control method, applied in the switching circuit as claimed in claim 1, wherein, turning on the solid state switch; closing the mechanical switch; Open the solid state switch. 6. The switching circuit control method according to claim 5, wherein, closing the mechanical switch while turning on the solid state switch, and/or After closing the mechanical switch, the solid state switch is opened when the current is transferred to the mechanical switch. 7. An automatic transfer switch device, characterized in that, the automatic transfer switch device comprises a main transfer switch component and a backup switch component, wherein, The main switch component comprises three mechanical switch circuits based on LC oscillation forced commutation type as claimed in claim 1, which are respectively used in the A-phase, B-phase and C-phase branches of three-phase electricity; The standby switch component includes three mechanical switch circuits based on LC oscillation forced commutation type as claimed in claim 1, which are respectively used in the A-phase, B-phase and C-phase branches of the three-phase electricity. 8. A power switching protection system, characterized in that, The power switching protection system includes: Working power and backup power; The automatic transfer switch device according to claim 7, wherein the main transfer switch component in the automatic transfer switch device is connected with the working power supply, and the backup transfer switch component is connected with the backup power supply; A monitoring system for monitoring the working state of the working power source and/or the backup power source; A protection system is controlled to control the automatic transfer switch device to switch between the main transfer switch part and the backup transfer switch part. 9. The power switching protection system according to claim 8, wherein, The monitoring system is further configured 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 in the main switch and standby switch parts according to the information. switch between. 10. The power switching protection system according to claim 8 or 9, characterized in that: The monitoring system also detects the disconnection state of the automatic transfer switch device, and feeds back the information of the disconnection state to the control protection system.

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