A low-cost power electronic AC arc-free circuit breaker system and control method thereof

Abstract

The present invention provides a low-cost power electronic AC arc-free circuit breaker system, including: three identical and independent current branches, which are connected in series with the three-phase power line to conduct the three-phase load current; an auxiliary branch shared by the three phases, which is connected in parallel with the three current branches in a time-sharing manner through two mechanical switching switches, and is used to assist in conducting the current during the opening, closing and reclosing processes; including a detection module, a control module and a drive module, which are respectively used to detect the three-phase voltage and current information, control the action timing of the three identical and independent current branches and the auxiliary branch shared by the three phases, and drive the auxiliary branch power semiconductor components and the mechanical switching switches to be turned on and off. The present invention also provides a control method for a low-cost power electronic AC arc-free circuit breaker system. The present invention avoids configuring an auxiliary branch for each of the three phases by sharing an auxiliary branch for the three phases, thereby greatly reducing the cost of the power electronic solid-state AC circuit breaker.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronic switches, and in particular to a low-cost power electronic AC arc-free circuit breaker system and a control method thereof. Background Art

[0002] With the advancement of the construction of a new power system based on new energy and the implementation of the photovoltaic county plan, the proportion of new energy in the AC distribution network will increase significantly. The volatility of new energy poses a challenge to the control of power flow and voltage in the distribution network. In addition, the change of power flow from traditional unidirectional to bidirectional in the distribution network further increases the complexity of power flow control. The active distribution network with power electronics utilizes the control flexibility of power electronic equipment such as voltage source converters and DC / DC converters, and has the capabilities of observable control and power flow optimization management, which has become the mainstream direction of distribution network development.

[0003] There are many power electronic devices in active distribution networks. Since the fault current tolerance of power electronic devices is weak, rapid protection is required. Compared with conventional mechanical switches, power electronic solid-state switches can achieve arc-free mechanical operating mechanisms and contacts, and noise-free switches have become a research hotspot. At present, the use of AC power electronic circuit breakers in three-phase systems requires three identical single-phase circuit breakers to be independently connected in series to the three-phase power line, resulting in high costs, which restricts the promotion and application of power electronic AC circuit breakers. Summary of the invention

[0004] In order to solve the above problems, the present invention aims to propose a low-cost power electronic AC arc-free circuit breaker system and a control method thereof. By sharing one auxiliary branch for three phases, it is avoided that each of the three phases is configured with one auxiliary branch, thereby overcoming the defects of low integration and large size of power electronic AC circuit breakers in the prior art, thereby greatly reducing the cost of power electronic solid-state AC circuit breakers.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A low-cost power electronic AC arc-free circuit breaker system, comprising a primary main circuit module and a secondary detection, control and drive module;

[0007] The primary main circuit module comprises: three identical and independent current-carrying branches, which are connected in series to the three-phase power line to conduct the three-phase load current; a three-phase common auxiliary branch, which is connected in parallel with the three current-carrying branches in a time-sharing manner through two mechanical switching switches to assist in conducting the current during the opening, closing and reclosing processes;

[0008] The secondary detection, control and drive module includes a detection module, a control module and a drive module, which are respectively used to detect three-phase voltage and current information, control the action timing of three identical and independent current-carrying branches and a three-phase common auxiliary branch, and drive the auxiliary branch power semiconductor components and mechanical switching switches to be turned on and off.

[0009] Furthermore, when applied in a low-voltage AC system scenario, the current branch includes a mechanical switch; when applied in a high-voltage AC system scenario, the current branch includes a mechanical switch and a current transfer module, and the mechanical switch is connected in series with the current transfer module.

[0010] Furthermore, the current transfer module includes a power semiconductor device.

[0011] Furthermore, the three-phase common auxiliary branch includes two mechanical switching switches and a power semiconductor component; a mechanical switching switch is connected in series at each end of the power semiconductor component, and the mechanical switching switch connects the power semiconductor component in parallel with the three-phase current-carrying branch in a time-sharing manner.

[0012] Furthermore, the power semiconductor component includes: a fully controlled power switch device series component and an MOV energy dissipation device.

[0013] Furthermore, the fully controlled power switch device series assembly includes two groups of IGBT series assemblies containing anti-parallel diodes, the two groups of IGBT series assemblies are connected in series in opposite directions, and the MOV energy dissipation device is connected in parallel with the two groups of IGBT series assemblies respectively.

[0014] Furthermore, the power semiconductor component includes: an IGBT series component, an MOV energy dissipation device and a diode bridge circuit. The IGBT series component includes a plurality of IGBTs connected in series in the same direction. The MOV energy dissipation device is connected in parallel with both ends of the IGBT series component and is connected in the diode bridge circuit.

[0015] Furthermore, the detection module, control module and drive module are respectively a three-phase power system phase voltage and phase current measurement circuit, a circuit breaker sequence control circuit, and a drive circuit for a power semiconductor device and a mechanical switch.

[0016] In order to achieve the above object, the present invention also provides a control method using the low-cost power electronic AC arc-free circuit breaker system as described above, which detects in real time through a detection module whether the three-phase power line corresponding to the three-phase current branch is faulty. When a fault is detected in the three-phase power line, the control method includes the following control process:

[0017] S1: Turn on the mechanical switch in the common auxiliary branch to connect the common auxiliary branch in parallel with the phase with the largest current;

[0018] S2: Turn on the power semiconductor components in the auxiliary branch to transfer the fault phase current to the common auxiliary branch;

[0019] S3: when the current of the phase-connected flow branch passes through zero, controlling the mechanical switch in the phase-connected flow branch to open;

[0020] S4: Ensure that when the mechanical switch in the current-carrying branch reaches the transient voltage opening distance, the power semiconductor components in the auxiliary branch are locked to achieve current shutoff;

[0021] S5: disconnect the mechanical switch in the common auxiliary branch, and connect it in parallel with the phase with the largest line current in the remaining two-phase flow branches, and repeat the above steps S2-S4;

[0022] S6: Disconnect the mechanical switching switch in the common auxiliary branch and connect it in parallel with the current-carrying branch of the last phase that has not been disconnected, and repeat the above steps S2-S4.

[0023] Beneficial effects: The present invention has the characteristics of high integration, compactness and low cost, and is easy to implement in engineering. When a power line fails, by controlling the coordination timing of the three-phase independent flow branch and the three-phase common auxiliary branch, the common auxiliary branch is time-division multiplexed, and the current in the three-phase flow branch is transferred to the common auxiliary branch in turn, and when the current in the flow branch passes zero, the mechanical switch of the flow branch is opened, thereby realizing three-phase arc-free disconnection in turn. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0025] Figure 1 A schematic structural diagram of a low-cost power electronic AC arc-free circuit breaker system according to an embodiment of the present invention;

[0026] Figure 2 A schematic diagram of a current flow branch when the low-cost power electronic AC arc-free circuit breaker system according to an embodiment of the present invention is applied to a low-voltage AC system scenario;

[0027] Figure 3 A schematic diagram of a current flow branch when the low-cost power electronic AC arc-free circuit breaker system according to an embodiment of the present invention is applied to a high-voltage AC system scenario;

[0028] Figure 4 A circuit diagram of a power semiconductor component in an auxiliary branch of a low-cost power electronic AC arc-free circuit breaker system according to an embodiment of the present invention using a fully controlled power switch device series component and an MOV energy dissipation device;

[0029] Figure 5A schematic diagram of a power semiconductor component in an auxiliary branch of a low-cost power electronic AC arc-free circuit breaker system according to an embodiment of the present invention using an IGBT series component, an MOV energy dissipation device, and a diode bridge circuit;

[0030] Figure 6 The present invention is a flowchart of a control method for a low-cost power electronic AC arc-free circuit breaker system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0032] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0033] Example 1

[0034] See also Figure 1-5 : A low-cost power electronic AC arc-free circuit breaker system, including a primary main circuit module and a secondary detection, control and drive module;

[0035] The primary main circuit module comprises: three identical and independent current-carrying branches, which are connected in series to the three-phase power line to conduct the three-phase load current; a three-phase common auxiliary branch, which is connected in parallel with the three current-carrying branches in a time-sharing manner through two mechanical switching switches to assist in conducting the current during the opening, closing and reclosing processes;

[0036] The secondary detection, control and drive module includes a detection module, a control module and a drive module, which are respectively used to detect three-phase voltage and current information, control the action timing of three identical and independent current-carrying branches and a three-phase common auxiliary branch, and drive the auxiliary branch power semiconductor components and mechanical switching switches to be turned on and off.

[0037] This embodiment avoids configuring one auxiliary branch for each of the three phases by sharing one auxiliary branch for the three phases, thereby overcoming the defects of low integration and large size of the power electronic AC circuit breaker in the prior art, thereby greatly reducing the cost of the power electronic solid-state AC circuit breaker.

[0038] In a specific example, see Figure 2 :When applied in a low voltage AC system scenario, the current branch includes a mechanical switch; see Figure 3 : When applied in a high-voltage AC system scenario, the current branch includes a mechanical switch and a current transfer module, and the mechanical switch is connected in series with the current transfer module.

[0039] It should be noted that when a power line fails, the coordination sequence of the three-phase independent flow branch and the three-phase common auxiliary branch is controlled, and the common auxiliary branch is time-division multiplexed, and the current in the three-phase flow branch is transferred to the common auxiliary branch in sequence, and when the current in the flow branch passes zero, the mechanical switch of the flow branch is opened, thereby realizing three-phase arc-free disconnection in sequence. The mechanical switch of this embodiment can adopt an ultra-high-speed vacuum switch.

[0040] In a specific example, the current transfer module includes a power semiconductor device.

[0041] It should be noted that the power semiconductor device of this embodiment may be formed by two IGBTs with anti-parallel diodes connected in series.

[0042] In a specific example, the three-phase common auxiliary branch includes two mechanical switching switches and a power semiconductor component; a mechanical switching switch is connected in series at each end of the power semiconductor component, and the mechanical switching switch connects the power semiconductor component in parallel with the three-phase current-carrying branch in a time-sharing manner.

[0043] In a specific example, see Figure 4 : The power semiconductor component includes: a fully controlled power switch device series component and an MOV energy dissipation device. The fully controlled power switch device series component includes two groups of IGBT series components containing anti-parallel diodes. The two groups of IGBT series components are connected in series in opposite directions. The MOV energy dissipation device is connected in parallel with the two groups of IGBT series components respectively.

[0044] The use of IGBT components as breaking components makes the circuit breaker have the advantages of fast breaking speed, no arc and simple driving structure. Two groups of IGBT series components are connected in series in opposite directions, so the power semiconductor components of this structure have the advantages of bidirectional current flow, no arc and fast breaking of AC circuits.

[0045] In a specific example, see Figure 5 The power semiconductor component includes an IGBT series component, a MOV energy dissipation device and a diode bridge circuit. The IGBT series component includes a plurality of IGBTs connected in series in the same direction. The MOV energy dissipation device is connected in parallel with both ends of the IGBT series component and connected in the diode bridge circuit.

[0046] The structure of IGBT series components and diode bridge circuit in parallel ensures the bidirectional flow of current and arc-free fast breaking function, while reducing the number of IGBT components and greatly reducing costs. Therefore, the power semiconductor components of this structure have the advantages of bidirectional current flow, arc-free fast breaking of AC circuits, high IGBT utilization rate and low cost.

[0047] In a specific example, the detection module, control module and drive module are respectively a three-phase power system phase voltage and phase current measurement circuit, a circuit breaker sequence control circuit, and a drive circuit for power semiconductor devices and mechanical switches.

[0048] Example 2

[0049] To achieve the above purpose, see Figure 6 This embodiment also provides a control method using the low-cost power electronic AC arc-free circuit breaker system as described above, which detects in real time through a detection module whether the three-phase power line corresponding to the three-phase current branch is faulty. When a fault is detected in the three-phase power line, the control process includes the following:

[0050] S1: Turn on the mechanical switch in the common auxiliary branch to connect the common auxiliary branch in parallel with the phase with the largest current;

[0051] S2: Turn on the power semiconductor components in the auxiliary branch to transfer the fault phase current to the common auxiliary branch;

[0052] S3: when the current of the phase-connected flow branch passes through zero, controlling the mechanical switch in the phase-connected flow branch to open;

[0053] S4: Ensure that when the mechanical switch in the current-carrying branch reaches the transient voltage opening distance, the power semiconductor components in the auxiliary branch are locked to achieve current shutoff;

[0054] S5: disconnect the mechanical switch in the common auxiliary branch, and connect it in parallel with the phase with the largest line current in the remaining two-phase flow branches, and repeat the above steps S2-S4;

[0055] S6: Disconnect the mechanical switching switch in the common auxiliary branch and connect it in parallel with the current-carrying branch of the last phase that has not been disconnected, and repeat the above steps S2-S4.

[0056] In this embodiment, when a fault occurs in the power line, by controlling the coordination timing of the three-phase independent current-carrying branch and the three-phase common auxiliary branch, the common auxiliary branch is time-division multiplexed, the current in the three-phase current-carrying branch is transferred to the common auxiliary branch in sequence, and when the current in the current-carrying branch passes through zero, the mechanical switch of the current-carrying branch is disconnected, thereby realizing arc-free disconnection of the three phases in sequence. In this embodiment, by sharing one auxiliary branch for three phases, it is avoided that one auxiliary branch is configured for each of the three phases, thereby greatly reducing the cost of the power electronic solid-state AC circuit breaker.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A low-cost power electronic AC arc-free circuit breaker system, characterized in that: It includes a primary main circuit module and a secondary detection, control and drive module; The primary main circuit module comprises: three identical and independent current-carrying branches, which are connected in series to the three-phase power line to conduct the three-phase load current; a three-phase common auxiliary branch, which is connected in parallel with the three current-carrying branches in a time-sharing manner through two mechanical switching switches to assist in conducting the current during the opening, closing and reclosing processes; The secondary detection, control and drive module includes a detection module, a control module and a drive module, which are respectively used to detect three-phase voltage and current information, control the action timing of three identical and independent current-carrying branches and a three-phase common auxiliary branch, and drive the auxiliary branch power semiconductor components and mechanical switching switches to turn on and off; The detection module detects in real time whether the three-phase power line corresponding to the three-phase flow branch is faulty. When a fault is detected in the three-phase power line, the following control process is included: S1: Turn on the mechanical switch in the common auxiliary branch to connect the common auxiliary branch in parallel with the phase with the largest current; S2: Turn on the power semiconductor components in the auxiliary branch to transfer the phase current to the common auxiliary branch; S3: when the current of the phase-connected flow branch passes through zero, controlling the mechanical switch in the phase-connected flow branch to open; S4: Ensure that when the mechanical switch in the current-carrying branch reaches the transient voltage opening distance, the power semiconductor components in the auxiliary branch are locked to achieve current shutoff; S5: disconnect the mechanical switch in the common auxiliary branch and connect it in parallel with the phase with the largest line current in the remaining two-phase current-carrying branches; S51: Turn on the power semiconductor components in the auxiliary branch to transfer the phase current to the common auxiliary branch; S52: when the current of the phase-connected flow branch passes through zero, controlling the mechanical switch in the phase-connected flow branch to open; S53: When the mechanical switch in the current-carrying branch reaches the transient voltage opening distance, the power semiconductor components in the auxiliary branch are locked to realize current shutoff; S6: disconnect the mechanical switch in the common auxiliary branch and connect it in parallel with the current-carrying branch of the last phase that has not been disconnected; S61: Turn on the power semiconductor components in the auxiliary branch to transfer the phase current to the common auxiliary branch; S62: when the current of the phase-connected flow branch passes through zero, controlling the mechanical switch in the phase-connected flow branch to open; S63: Ensure that when the mechanical switch in the current-carrying branch reaches the transient voltage opening distance, the power semiconductor components in the auxiliary branch are locked to shut off the current.

2. The low-cost power electronic AC arc-free circuit breaker system according to claim 1, characterized in that: When applied in a low-voltage AC system scenario, the current branch includes a mechanical switch; when applied in a high-voltage AC system scenario, the current branch includes a mechanical switch and a current transfer module, and the mechanical switch is connected in series with the current transfer module.

3. The low-cost power electronic AC arc-free circuit breaker system according to claim 2, characterized in that: The current transfer module includes a power semiconductor device.

4. The low-cost power electronic AC arc-free circuit breaker system according to claim 1, characterized in that: The three-phase common auxiliary branch includes two mechanical switching switches and a power semiconductor component; a mechanical switching switch is connected in series at each end of the power semiconductor component, and the mechanical switching switch connects the power semiconductor component in parallel with the three-phase current-carrying branch in a time-sharing manner.

5. The low-cost power electronic AC arc-free circuit breaker system according to claim 4, characterized in that: The power semiconductor assembly includes: a fully controlled power switch device series assembly and an MOV energy dissipation device.

6. The low-cost power electronic AC arc-free circuit breaker system according to claim 5, characterized in that: The fully controlled power switch device series assembly comprises two groups of IGBT series assemblies containing anti-parallel diodes, the two groups of IGBT series assemblies are connected in series in opposite directions, and the MOV energy dissipation device is connected in parallel with the two groups of IGBT series assemblies respectively.

7. The low-cost power electronic AC arc-free circuit breaker system according to claim 4, characterized in that: The power semiconductor component includes: an IGBT series component, a MOV energy dissipation device and a diode bridge circuit. The IGBT series component includes a plurality of IGBTs connected in series in the same direction. The MOV energy dissipation device is connected in parallel with both ends of the IGBT series component and is connected in the diode bridge circuit.

8. The low-cost power electronic AC arc-free circuit breaker system according to claim 1, characterized in that: The detection module, control module and drive module are respectively a three-phase power system phase voltage and phase current measurement circuit, a circuit breaker sequence control circuit, and a drive circuit for a power semiconductor device and a mechanical switch.

Images