CN118675951A - A low voltage naturally commutated hybrid DC circuit breaker and commutation method - Google Patents

Abstract

The embodiment of the present disclosure discloses a low-voltage naturally commutated hybrid DC circuit breaker and a commutation method. The circuit breaker includes a mechanical switch and a commutation module. The commutation module includes an energy extraction unit, a voltage conversion unit, a control unit, a drive unit, a power electronic device and a zinc oxide lightning arrester MOV; the commutation module is connected in parallel to both ends of the mechanical switch. During the opening and closing process of the mechanical switch, the arc voltage at both ends of the mechanical switch is used to commutate the fault current into the commutation module; in the exemplary embodiment of the present disclosure, the commutation module obtains energy through arc energy and does not require external power supply; the mechanical switch has an internal integrated sensor to control self-tripping and does not require external control; the commutation process uses arc voltage for self-commutation; the shutdown time of the commutation module depends on the current commutation process, and the power electronic device shuts down automatically.

Description

A low voltage naturally commutated hybrid DC circuit breaker and commutation method

Technical Field

The disclosed embodiments relate to the technical field of circuit breakers, and in particular to a low-voltage naturally commutated hybrid DC circuit breaker and a commutation method.

Background Art

With the application and popularization of DC systems, there are more and more DC power-consuming devices in scenarios such as data centers, energy storage systems, and smart homes, and the demand for low-voltage DC circuit breakers is also increasing. Since DC short-circuit current has no AC zero-crossing point, traditional AC circuit breakers cannot be used in DC systems. The existing solution is to use mechanical switches to accelerate arc extinguishing by using arc-extinguishing grids, external magnetic fields, and increasing the opening distance. Although the structure is simple, the long-term ablation each time the switch is opened causes the life of the mechanical switch contacts to be drastically reduced. Moreover, under low current conditions, the above method cannot effectively extinguish the arc, which poses a risk.

Summary of the invention

The embodiments of the present disclosure provide a low-voltage naturally commutated hybrid DC circuit breaker and a commutation method to solve or alleviate one or more of the above technical problems in the prior art.

According to one aspect of the present disclosure, there is provided a low-voltage naturally commutated hybrid DC circuit breaker, comprising a mechanical switch and a commutation module, wherein the commutation module comprises an energy taking unit, a voltage conversion unit, a control unit, a drive unit, a power electronic device and a zinc oxide arrester MOV;

The commutation module is connected in parallel to both ends of the mechanical switch, and during the opening and closing process of the mechanical switch, the arc voltage at both ends of the mechanical switch is used to commutate the fault current to the commutation module;

The energy extraction unit is used to extract energy through arc energy after the mechanical switch opens the contacts;

The voltage conversion unit is used to convert the arc voltage into the voltage level required by the control unit and the drive unit;

The control unit and the driving unit are used to turn on the power electronic device after the energy taking unit takes energy through the arc energy. When the power electronic device is turned on, the fault current is driven by the arc voltage to commutate from the mechanical switch to the power electronic device, and the mechanical switch extinguishes the arc;

The control unit is also used to shut down the power electronic device when it is detected that the voltage drops to the action threshold after the mechanical switch extinguishes the arc;

The power electronic device is used to complete fault current interruption after the fault current is commutated into the commutation module;

The zinc oxide arrester MOV is used to absorb energy in the system after the power electronic device is turned off, and complete fault current breaking and short circuit fault isolation.

In a possible implementation, the mechanical switch is used to automatically trip and open contacts when a current change is detected after a short circuit fault occurs.

In a possible implementation, the mechanical switch is a vacuum switch or a molded case circuit breaker.

In a possible implementation, the power electronic device is an IGBT, an IEGT, an IGCT or a silicon carbide device.

According to one aspect of the present disclosure, a commutation method for a low-voltage naturally commutated hybrid DC circuit breaker is provided, comprising a mechanical switch and a commutation module, wherein the commutation module comprises an energy taking unit, a voltage conversion unit, a control unit, a drive unit, a power electronic device and a zinc oxide arrester MOV;

During the opening and closing process of the mechanical switch, the arc voltage at both ends of the mechanical switch is used to commutate the fault current to the commutation module connected in parallel at both ends of the mechanical switch;

After the mechanical switch opens the contacts, the energy extraction unit extracts energy through the arc energy;

The arc voltage is converted into the voltage level required by the control unit and the drive unit by the voltage conversion unit;

After the energy extraction unit extracts energy through arc energy, the control unit and the drive unit start up and turn on the power electronic device. When the power electronic device is turned on, the fault current is driven by the arc voltage to commutate from the mechanical switch to the power electronic device, and the mechanical switch extinguishes the arc.

When the voltage drops to the action threshold after the arc of the mechanical switch is extinguished, the control unit controls the power electronic device to be turned off;

After the fault current is commutated into the commutation module, the fault current is interrupted by power electronic devices;

After the power electronic device is turned off, the energy in the system is absorbed by the zinc oxide lightning arrester MOV to complete the fault current interruption and short circuit fault isolation.

In a possible implementation, the method of utilizing arc voltage at both ends of the mechanical switch to commutate the fault current to the commutation modules connected in parallel at both ends of the mechanical switch during the opening and closing of the mechanical switch includes:

When a short circuit occurs, the current increases, and the mechanical switch automatically trips and opens the contacts after detecting the current change.

In a possible implementation, the mechanical switch is a vacuum switch or a molded case circuit breaker.

In a possible implementation, the power electronic device is an IGBT, an IEGT, an IGCT or a silicon carbide device.

The exemplary embodiments of the present disclosure have the following beneficial effects: in the exemplary embodiments of the present disclosure, the commutation module obtains energy through arc energy, without the need for external power supply; the mechanical switch has an internal integrated sensor to control self-tripping, without the need for external control; the commutation process utilizes arc voltage for self-commutation; the shutdown time of the commutation module depends on the current commutation process, and the power electronic device shuts down automatically.

The details of one or more embodiments of the present application are presented in the following drawings and descriptions. Other features and advantages of the present application will become apparent from the accompanying drawings. It should be understood that the above general description and the detailed descriptions below are only exemplary and explanatory and cannot limit the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

FIG1 is a topological diagram of a low-voltage naturally commutated hybrid DC circuit breaker of the present exemplary embodiment;

FIG2 is a schematic diagram of the first stage of the breaking process of the adaptive low-voltage naturally commutated hybrid DC circuit breaker of the exemplary embodiment;

3 is a schematic diagram of the second stage of the breaking process of the adaptive low-voltage naturally commutated hybrid DC circuit breaker of this exemplary embodiment;

4 is a schematic diagram of the third stage of the breaking process of the adaptive low-voltage naturally commutated hybrid DC circuit breaker of this exemplary embodiment;

5 is a schematic diagram of the fourth stage of the breaking process of the adaptive low-voltage naturally commutated hybrid DC circuit breaker of this exemplary embodiment;

6 is a schematic diagram of current changes in the mechanical switch, energy-consuming branch and converter module and voltage changes at both ends of the circuit breaker during the breaking process of this exemplary embodiment;

FIG. 7 is a flow chart of a commutation method for a low-voltage naturally commutated hybrid DC circuit breaker according to the exemplary embodiment.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as being limited to the examples set forth herein; on the contrary, these embodiments are provided so that the present disclosure will be more comprehensive and complete, and the concepts of the example embodiments are fully conveyed to those skilled in the art. The described features, structures, or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced while omitting one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other cases, known technical solutions are not shown or described in detail to avoid obscuring various aspects of the present disclosure.

In addition, the accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware units or integrated circuits, or implemented in different networks and/or processor devices and/or microcontroller devices.

The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the steps. For example, some steps may be decomposed, while some steps may be combined or partially combined, so the actual execution order may change according to the actual situation.

The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example.

In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or sub-modules is not necessarily limited to those steps or sub-modules explicitly listed, but may include other steps or sub-modules not explicitly listed or inherent to these processes, methods, products, or apparatuses.

Fig. 1 is a topological diagram of a low-voltage naturally commutated hybrid DC circuit breaker of the exemplary embodiment. As shown in Fig. 1, the exemplary embodiment of the present disclosure provides a low-voltage naturally commutated hybrid DC circuit breaker, including: a mechanical switch and a commutation module, the commutation module including an energy extraction unit, a voltage conversion unit, a control unit, a drive unit, a power electronic device and a zinc oxide arrester MOV;

The commutation module is connected in parallel to both ends of the mechanical switch, and during the opening and closing process of the mechanical switch, the arc voltage at both ends of the mechanical switch is used to commutate the fault current to the commutation module;

The power electronic device is used to complete fault current interruption after the fault current is commutated into the commutation module.

In this exemplary embodiment, by connecting the commutation modules in parallel at both ends of the mechanical switch, the arc voltage is used to commutate the fault current to the power electronic branch in the module during the breaking process, and the power electronic device is used to complete the fault current breaking.

Specifically, the mechanical switch is used to automatically trip and open contacts when a current change is detected after a short circuit fault occurs.

FIG2 is a schematic diagram of the first stage of the breaking process of the adaptive low-voltage natural commutation hybrid DC circuit breaker of this exemplary embodiment, and FIG6 is a schematic diagram of the current changes of the mechanical switch, energy-consuming branch and commutation module and the voltage changes at both ends of the circuit breaker during the breaking process of this exemplary embodiment; FIG2 (the flow direction of the current is shown by the arrow in the figure) is combined with FIG6. Under normal circumstances, the current flows through the mechanical switch and the conduction loss is low. When a short circuit fault occurs, the current increases, and the mechanical switch automatically trips after detecting the current change, and the contacts are pulled apart.

Specifically, the energy extraction unit is used to extract energy through arc energy after the mechanical switch opens the contacts;

The voltage conversion unit is used to convert the arc voltage into the voltage level required by the control unit and the drive unit;

The control unit and the drive unit are used to turn on the power electronic device after the energy taking unit takes energy through arc energy. When the power electronic device is turned on, the fault current is driven by the arc voltage to commutate from the mechanical switch to the power electronic device, and the mechanical switch extinguishes the arc.

It is worth noting that as long as the energy acquisition unit, voltage conversion unit, and driving unit circuit can realize the corresponding functions, they should fall within the protection scope of this embodiment.

Figure 3 is a schematic diagram of the second stage of the breaking process of the adaptive low-voltage natural commutation hybrid DC circuit breaker of this exemplary embodiment. Figure 3 (the direction of current flow is shown by the arrow in the figure) is combined with Figure 6. In this exemplary embodiment, the mechanical switch automatically trips after detecting a current change. After the contacts are pulled apart, the short-circuit current still flows through the mechanical switch, the contacts arc, and the energy extraction unit of the commutation module extracts energy through the arc energy.

Figure 4 is a schematic diagram of the third stage of the breaking process of the adaptive low-voltage natural commutation hybrid DC circuit breaker of this exemplary embodiment. Figure 4 (the direction of current flow is shown by the arrow in the figure) is combined with Figure 6. In this exemplary embodiment, when the energy acquisition unit obtains sufficient energy, the control unit and the drive unit at the rear end start working and turn on the power electronic devices. At the same time, the fault current is driven by the arc voltage to commutate from the mechanical switch to the power electronic branch, and the mechanical switch extinguishes the arc.

The control unit is also used to shut down the power electronic device when it is detected that the voltage drops to the action threshold after the mechanical switch extinguishes the arc;

The power electronic device is used to complete fault current interruption after the fault current is commutated into the commutation module;

The zinc oxide arrester MOV is used to absorb energy in the system after the power electronic device is turned off, and complete fault current breaking and short circuit fault isolation.

FIG5 is a schematic diagram of the fourth stage of the breaking process of the adaptive low-voltage natural commutation hybrid DC circuit breaker of this exemplary embodiment. FIG5 (the direction of current flow is shown by the arrow in the figure) is combined with FIG6. In this exemplary embodiment, as the mechanical switch extinguishes the arc, the energy extraction unit cannot obtain energy, and the voltage gradually decreases. When the control unit detects that the voltage drops to the action threshold, the power electronic device is turned off, the voltage is established at both ends of the device, and the current is commutated to the MOV branch. After the MOV absorbs energy in the system, the fault current is interrupted and the short-circuit fault is isolated.

Specifically, the mechanical switch is a vacuum switch or a molded case circuit breaker.

It is worth noting that the vacuum switch or molded case circuit breaker is only a preferred implementation of the mechanical switch, and the protection scope of the mechanical switch is not limited to this embodiment.

Specifically, the power electronic device is an IGBT, IEGT, IGCT or a silicon carbide device.

It is worth noting that IGBT, IEGT, IGCT or silicon carbide devices are only preferred implementations of power electronic devices, and the protection scope of power electronic devices is not limited to these embodiments.

FIG7 is a flow chart of a commutation method of a low-voltage naturally commutated hybrid DC circuit breaker according to an exemplary embodiment of the present invention. As shown in FIG7 , an exemplary embodiment of the present disclosure provides a commutation method of a low-voltage naturally commutated hybrid DC circuit breaker, including:

During the opening and closing process of the mechanical switch, the arc voltage at both ends of the mechanical switch is used to commutate the fault current to the commutation module connected in parallel at both ends of the mechanical switch; it is worth noting that the power supply of the commutation module is self-powered and no external power supply is required; the mechanical switch can be a vacuum switch or a molded case circuit breaker.

Specifically, in the process of breaking the mechanical switch, the method of utilizing the arc voltage at both ends of the mechanical switch to commutate the fault current to the commutation modules connected in parallel at both ends of the mechanical switch includes:

When a short circuit occurs, the current increases, and the mechanical switch automatically trips and opens the contacts after detecting the current change.

Specifically, the short circuit fault occurs, the current increases, and the mechanical switch automatically trips and opens the contacts after detecting the current change, which includes:

After the mechanical switch opens the contacts, the energy extraction unit in the commutation module extracts energy through arc energy;

The arc voltage is converted into the voltage level required by the control unit and the drive unit by the voltage conversion unit;

After the energy extraction unit extracts energy through arc energy, the control unit and the drive unit in the commutation module are started, and the power electronic device is turned on. When the power electronic device is turned on, the fault current is driven by the arc voltage to commutate from the mechanical switch to the power electronic device, and the mechanical switch extinguishes the arc. It is worth noting that the power electronic device includes but is not limited to IGBT, IEGT, IGCT and silicon carbide devices.

Specifically, in the process of breaking the mechanical switch, the arc voltage at both ends of the mechanical switch is used to commutate the fault current to the commutation module connected in parallel at both ends of the mechanical switch, and the fault current breaking is completed by the power electronic device in the commutation module, which specifically includes:

After the mechanical switch extinguishes the arc, the control unit detects that the voltage drops to the action threshold and shuts down the power electronic device;

After the power electronic devices are turned off, the zinc oxide arrester MOV in the commutation module absorbs the energy in the system, completing the fault current breaking and short circuit fault isolation.

Specifically, the mechanical switch is a vacuum switch or a molded case circuit breaker.

Specifically, the power electronic device is an IGBT, IEGT, IGCT or a silicon carbide device.

In this exemplary embodiment, under normal circumstances, the current flows through the mechanical switch, and the conduction loss is low. When a short-circuit fault occurs, the current increases, and the mechanical switch automatically trips after detecting the current change, and the contacts are pulled apart. Since the short-circuit current still flows through the mechanical switch, the contacts arc, and the energy extraction unit of the commutation module extracts energy through the arc energy. When the energy extraction unit obtains enough energy, the control unit and the driver IC at the rear end start working and turn on the power electronic device. At the same time, the fault current is driven by the arc voltage and commutates from the mechanical switch to the power electronic branch, and the mechanical switch extinguishes the arc. As the mechanical switch extinguishes the arc, the energy extraction unit cannot obtain energy and the voltage gradually decreases. When the control unit detects that the voltage drops to the action threshold, the power electronic device is turned off, a voltage is established at both ends of the device, and the current is commutated to the MOV branch. After the MOV absorbs the energy in the system, the fault current interruption and short-circuit fault isolation are completed.

By connecting the commutation modules in parallel at both ends of the mechanical switch, the arc voltage is used to commutate the fault current to the power electronic branch in the module during the breaking process, and the power electronic devices are used to complete the fault current breaking. The drive and control of the power electronic devices are integrated in the commutation module, and the mechanical switch is used to burn arcs to obtain energy, realizing self-energy extraction; when the current is fully commutated, the power supply of the commutation module disappears, and when the energy storage element cannot support the module energy supply, the power electronic device is automatically shut down to achieve self-shutdown. This method is conducive to reducing the fault current breaking time, reducing the ablation energy of the mechanical switch contact, and improving the electrical life of the circuit breaker.

In summary, the commutation module of this embodiment obtains energy through arc energy, without the need for external power supply; the mechanical switch has an internal integrated sensor to control self-tripping, without the need for external control; the commutation process uses arc voltage for self-commutation; the commutation module shutdown time depends on the current commutation process, and the power electronic device shuts down automatically. Therefore, the circuit breaker of the present invention is an adaptive circuit breaker that is self-triggering, self-energy-drawing, and self-commutating. It can commutate and shut down according to the fault situation without the need for external control and detection.

The above are only preferred implementations of the present disclosure, and the protection scope of the present disclosure is not limited to the above embodiments. All technical solutions under the concept of the present disclosure belong to the protection scope of the present disclosure. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present disclosure should be regarded as the protection scope of the present disclosure.

Claims (8)

1. The low-voltage natural current-converting hybrid direct-current breaker is characterized by comprising a mechanical switch and a current-converting module, wherein the current-converting module comprises an energy-taking unit, a voltage conversion unit, a control unit, a driving unit, a power electronic device and a zinc oxide lightning arrester MOV;

The converter modules are connected in parallel with two ends of the mechanical switch, and fault current is converted into the converter modules by utilizing arc voltages at the two ends of the mechanical switch in the process of switching on and off the mechanical switch;

The energy-taking unit is used for taking energy through arc energy after the mechanical switch pulls the contact;

the voltage conversion unit is used for converting the arc voltage into voltage levels required by the control unit and the driving unit;

The control unit and the driving unit are used for conducting the power electronic device after the energy taking unit takes energy through arc energy, and when the power electronic device is conducted, fault current is driven by arc voltage to be converted from the mechanical switch to the power electronic device, and the mechanical switch is in arc extinction;

The control unit is also used for turning off the power electronic device when the voltage is detected to drop to the action threshold value after the arc of the mechanical switch is extinguished;

the power electronic device is used for completing fault current switching-on and switching-off after fault current is commutated into the commutation module;

the zinc oxide arrester MOV is used for absorbing energy in a system after a power electronic device is turned off, and fault current is turned on and short-circuit fault isolation is completed.

2. The low voltage natural commutation type hybrid dc circuit breaker of claim 1, wherein the mechanical switch is configured to automatically trip and pull the contacts apart upon detection of a current change after a short circuit fault.

3. The low voltage natural commutation type hybrid dc circuit breaker of claim 1 or 2, wherein the mechanical switch is a vacuum switch or a molded case circuit breaker.

4. The low voltage natural commutation type hybrid dc breaker of claim 1 or 2, wherein the power electronic device is IGBT, IEGT, IGCT or a silicon carbide device.

5. The commutation method of the low-voltage natural commutation type hybrid direct current breaker is characterized by comprising a mechanical switch and a commutation module, wherein the commutation module comprises an energy taking unit, a voltage conversion unit, a control unit, a driving unit, a power electronic device and a zinc oxide lightning arrester MOV;

in the switching-on and switching-off process of the mechanical switch, the arc voltage at the two ends of the mechanical switch is utilized to commutate fault current into a commutating module with the two ends of the mechanical switch connected in parallel;

After the mechanical switch pulls the contact, the energy taking unit takes energy through arc energy;

converting the arc voltage into voltage levels required by the control unit and the driving unit through a voltage conversion unit;

after the energy taking unit takes energy through arc energy, the control unit and the driving unit are started to conduct the power electronic device, when the power electronic device is conducted, fault current is driven by arc voltage to be commutated from the mechanical switch to the power electronic device, and the mechanical switch is in arc extinction;

When the voltage drop to the action threshold value is detected after the arc of the mechanical switch is extinguished, the power electronic device is controlled to be turned off by the control unit;

after the fault current is commutated into a commutation module, the fault current is switched off through a power electronic device;

after the power electronic device is turned off, the energy in the system is absorbed by the zinc oxide arrester MOV, so that fault current is turned on and short-circuit fault isolation is completed.

6. The method for converting a low-voltage natural commutation type hybrid dc breaker according to claim 5, wherein before converting a fault current into a parallel commutation module at two ends of the mechanical switch by using arc voltage at two ends of the mechanical switch during the turning-on and turning-off of the mechanical switch, the method comprises:

Short-circuit fault occurs, the current increases, and the mechanical switch automatically trips and pulls the contact open after detecting the current change.

7. The method of commutating a low voltage natural commutating hybrid dc circuit breaker according to claim 5 or 6, wherein the mechanical switch is a vacuum switch or a molded case circuit breaker.

8. The method of commutating a low voltage natural commutation type hybrid dc circuit breaker of claim 5 or 6, wherein the power electronic device is IGBT, IEGT, IGCT or a silicon carbide device.