Single-action operation type bidirectional direct-current solid-state circuit breaker and control method thereof

Abstract

The invention relates to the technical field of circuit breakers, and provides a single-action operation type bidirectional direct-current solid-state circuit breaker and a control method thereof.The single-action operation type bidirectional direct-current solid-state circuit breaker comprises an insulated gate bipolar transistor Q1, a diode D1, a thyristor T1, a thyristor T2, a thyristor T3, a thyristor T4, a piezoresistor MOV1, a control unit, a resistor R1 and a capacitor C1; the collector electrode of the insulated gate bipolar transistor Q1 is connected with the cathodes of the thyristor T1 and the thyristor T2, and the emitter electrode of the insulated gate bipolar transistor Q1 is connected with the anodes of the thyristor T3 and the thyristor T4; the defects in the prior art are overcome, the circuit breaker is connected in series in a direct-current line, when no short-circuit fault occurs, the circuit breaker can work under the normal condition, the circuit performance is not affected, and the bidirectional transmission performance is achieved; when a short-circuit fault occurs, the circuit breaker can quickly block short-circuit current, has the characteristics of high response speed and high reliability, and can ensure the safety of a system.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit breakers, and in particular to a single-action bidirectional DC solid-state circuit breaker and a control method thereof. Background Art

[0002] DC short-circuit fault protection is a key technology for DC power transmission. Due to the low impedance and low inertia characteristics of DC transmission systems, the fault current rises extremely quickly after a short-circuit fault occurs. If not promptly addressed, the system will suffer significant damage.

[0003] Furthermore, DC fault currents do not have a zero-crossing point, so directly interrupting a DC short-circuit fault would generate a significant overvoltage at the switch. Therefore, solid-state circuit breakers with fast response capabilities are currently one of the effective solutions to this problem. However, current solid-state circuit breakers require controlling a large number of switches to interrupt the fault current, and the control steps are very cumbersome.

[0004] In view of the above problems, we propose a single-action bidirectional DC solid-state circuit breaker and a control method thereof. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention provides a single-action bidirectional DC solid-state circuit breaker and a control method thereof, which overcomes the shortcomings of the existing technology and has a reasonable design. Compared with traditional solid-state circuit breakers, it has a simple structure, a simple control strategy, and a low cost, and can reduce power loss during system operation.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] A single-action bidirectional DC solid-state circuit breaker includes: an insulated gate bipolar transistor Q1, a diode D1, a thyristor T1, a thyristor T2, a thyristor T3, a thyristor T4, a varistor MOV1, a control unit, a resistor R1, and a capacitor C1; the collector of the insulated gate bipolar transistor Q1 is connected to the cathodes of the thyristors T1 and T2, and the emitter of the insulated gate bipolar transistor Q1 is connected to the anodes of the thyristors T3 and T4;

[0008] A cathode of the diode D1 is connected to the collector of the insulated gate bipolar transistor Q1 , and an anode of the diode D1 is connected to the emitter of the insulated gate bipolar transistor Q1 .

[0009] Preferably, the anode of the thyristor T1 and the cathode of the thyristor T3 are connected and then connected with the DC terminal P1, the cathode of the thyristor T1 is connected with the cathode of the thyristor T2, the anode of the thyristor T2 is connected with the cathode of the thyristor T4 and then connected with the DC terminal P2, and the anode of the thyristor T3 is connected with the anode of the thyristor T4.

[0010] Preferably, the insulated gate bipolar transistor Q1 and the diode D1 constitute a main switch branch, and the thyristor T1, the thyristor T2, the thyristor T3 and the thyristor T4 constitute a bidirectional forced commutation branch.

[0011] Preferably, the insulated gate bipolar transistor Q1 is an N-channel insulated gate bipolar transistor.

[0012] Preferably, the resistor R1 and the capacitor C1 are connected in series and then connected in parallel with the voltage-dependent resistor MOV1, the emitter and the collector of the insulated gate bipolar transistor Q1 are connected in parallel with the diode D1, the diode D1 is connected in parallel with the voltage-dependent resistor MOV1, and the base of the insulated gate bipolar transistor Q1, the thyristor T1, the thyristor T2, the thyristor T3 and the thyristor T4 are connected with the control unit.

[0013] Preferably, the resistor R1 and the capacitor C1 are connected in series and then connected in parallel with the voltage-dependent resistor MOV1 to constitute an energy absorption branch, which is used for limiting overvoltage and absorbing fault energy.

[0014] Preferably, the resistor R1 and the capacitor C1 constitute an energy dissipation loop, which is used for releasing the residual energy stored in the capacitor C1 after fault isolation.

[0015] A control method of a single-acting operation type bidirectional DC solid-state circuit breaker, used for realizing the circuit breaker, comprising the following control process:

[0016] When the single-acting operation type bidirectional DC solid-state circuit breaker is in a normal working state, the DC terminal P1 is connected with a DC power supply, the DC terminal P2 is connected with a load, and a working current flows from the DC terminal P1, through the thyristor T1, the insulated gate bipolar transistor Q1 and the thyristor T4 and then flows into the DC terminal P2, forming a bidirectional conduction main loop, at this time, the insulated gate bipolar transistor Q1 keeps in a conduction state, the thyristor T1 and the thyristor T4 keep in a conduction state through gate signals, the voltage-dependent resistor MOV1 is in a high resistance state, and the resistor R1 and the capacitor C1 connected in series only serve as a buffer circuit to inhibit switching transient overvoltage.

[0017] When a short circuit fault occurs at the DC terminal P2, the current in the line sharply increases, the insulated gate bipolar transistor Q1 receives a control instruction from the control unit and immediately turns off, and the control unit triggers the thyristor T2 and the thyristor T3 to turn on, forming a forced commutation path, so as to reduce the short circuit current.

[0018] After the insulated gate bipolar transistor Q1 is turned off, the voltage across it rises rapidly. When the voltage reaches the clamping voltage of the varistor MOV1, the varistor and the energy absorption branch start to work to absorb the short-circuit energy and limit the overvoltage. The fault current gradually decreases under the combined action of the commutation path and the energy absorption branch. When the fault current drops to zero, the thyristor T1 and the thyristor T4 automatically turn off because the current is less than their holding current, successfully isolating the short-circuit fault.

[0019] After the fault is isolated, the insulated gate bipolar transistor Q1 remains in the off state, and the energy stored in the capacitor C1 is released and consumed through the resistor R1 to form a loop. When the current of the energy dissipation loop drops to zero, the energy release process of the capacitor C1 ends.

[0020] After confirming that the fault has been cleared, the control unit performs the reclosing operation again, the thyristor T1, the thyristor T4 and the insulated gate bipolar transistor Q1 are turned on, the DC voltage returns to normal, and the DC microgrid resumes operation.

[0021] The present invention provides a single-action bidirectional DC solid-state circuit breaker and its control method. The invention has the following beneficial effects: when the circuit breaker is connected in series in a DC line, it can operate normally when no short-circuit fault occurs, without affecting circuit performance, and has bidirectional transmission capability.

[0022] When a short circuit occurs, the circuit breaker can quickly block the short circuit current. It has the characteristics of fast response speed and high reliability, and can ensure the safety of the system.

[0023] The energy absorption branch and energy dissipation circuit only need to control the switch of one insulated gate bipolar transistor Q1 to achieve energy dissipation and energy absorption during a short circuit, thereby reducing the control strategy. Therefore, the single-action bidirectional DC solid-state circuit breaker can effectively handle the short-circuit fault of the DC microgrid and provide protection for the safe operation of the DC system.

[0024] The control unit can effectively handle the short-circuit fault of the DC microgrid through the control strategy, providing guarantee for the safe operation of the DC system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the circuit topology of the single-action bidirectional DC solid-state circuit breaker of the present invention;

[0026] Figure 2 This is a schematic diagram of the first working process of the topological structure of the single-action bidirectional DC solid-state circuit breaker of the present invention;

[0027] Figure 3 This is a schematic diagram of the second working process of the topological structure of the single-action bidirectional DC solid-state circuit breaker of the present invention;

[0028] Figure 4 A schematic diagram of the third working process of the topological structure of the single-action bidirectional DC solid-state circuit breaker of the present invention;

[0029] Figure 5 A schematic diagram of a fourth working process of the topological structure of a single-action bidirectional DC solid-state circuit breaker according to the present invention;

[0030] Figure 6 This is the short-circuit current waveform diagram of the present invention;

[0031] Figure 7 This is the voltage waveform of the capacitor C1 of the present invention;

[0032] To make the objectives, 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 of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0033] Refer to the attached Figure 1-Figure 7 A single-action bidirectional DC solid-state circuit breaker includes: an insulated gate bipolar transistor Q1, a diode D1, a thyristor T1, a thyristor T2, a thyristor T3, a thyristor T4, a varistor MOV1, a control unit, a resistor R1, and a capacitor C1; the collector of the insulated gate bipolar transistor Q1 is connected to the cathodes of the thyristors T1 and T2, and the emitter of the insulated gate bipolar transistor Q1 is connected to the anodes of the thyristors T3 and T4;

[0034] A cathode of the diode D1 is connected to the collector of the insulated gate bipolar transistor Q1 , and an anode of the diode D1 is connected to the emitter of the insulated gate bipolar transistor Q1 .

[0035] The anode of the thyristor T1 and the cathode of the thyristor T3 are connected to the DC terminal P1, the cathode of the thyristor T1 is connected to the cathode of the thyristor T2, the anode of the thyristor T2 and the cathode of the thyristor T4 are connected to the DC terminal P2, and the anode of the thyristor T3 is connected to the anode of the thyristor T4.

[0036] The insulated gate bipolar transistor Q1 and the diode D1 form a main switching branch, and the thyristor T1, the thyristor T2, the thyristor T3 and the thyristor T4 form a bidirectional commutation branch.

[0037] The insulated gate bipolar transistor Q1 is an N-channel insulated gate bipolar transistor.

[0038] The resistor R1 and the capacitor C1 are connected in series and then in parallel with the varistor MOV1. The emitter and collector of the insulated gate bipolar transistor Q1 are connected in parallel with the diode D1. The diode D1 is connected in parallel with the varistor MOV1. The base of the insulated gate bipolar transistor Q1, the thyristor T1, the thyristor T2, the thyristor T3, and the thyristor T4 are all connected to the control unit.

[0039] The resistor R1 and the capacitor C1 are connected in series and then in parallel with the varistor MOV1 to form an energy absorption branch, which is used to limit overvoltage and absorb fault energy.

[0040] The resistor R1 and the capacitor C1 form an energy dissipation loop, which is used to release the residual energy stored in the capacitor C1 after fault isolation.

[0041] A control method for a single-action bidirectional DC solid-state circuit breaker, used to implement the circuit breaker, includes the following control process:

[0042] When the single-action bidirectional DC solid-state circuit breaker is in normal operation, DC terminal P1 is connected to the DC power supply, and DC terminal P2 is connected to the load. The operating current flows from DC terminal P1 through thyristor T1, then through insulated gate bipolar transistor Q1, and finally through thyristor T4 into DC terminal P2, forming a bidirectional conductive main circuit. At this time, insulated gate bipolar transistor Q1 remains in the on state, and thyristors T1 and T4 are kept on by gate signals; varistor MOV1 is in a high-impedance state, and the series branch of resistor R1 and capacitor C1 only acts as a buffer circuit to suppress switching transient overvoltages;

[0043] When a short circuit occurs at the DC terminal P2, the current in the line increases sharply. The insulated gate bipolar transistor Q1 receives the control instruction from the control unit and immediately turns off. At the same time, the control unit triggers the thyristor T2 and thyristor T3 to turn on, forming a forced commutation path to reduce the short circuit current.

[0044] After the insulated gate bipolar transistor Q1 is turned off, the voltage across it rises rapidly. When the voltage reaches the clamping voltage of the varistor MOV1, the varistor and the energy absorption branch start to work to absorb the short-circuit energy and limit the overvoltage. The fault current gradually decreases under the combined action of the commutation path and the energy absorption branch. When the fault current drops to zero, the thyristor T1 and the thyristor T4 automatically turn off because the current is less than their holding current, successfully isolating the short-circuit fault.

[0045] After the fault is isolated, the insulated gate bipolar transistor Q1 remains in the off state, and the energy stored in the capacitor C1 forms a loop through the resistor R1 for release and consumption. When the current in the energy dissipation loop drops to zero (or the voltage of the capacitor C1 drops to a sufficiently low level), the energy release process of the capacitor C1 ends.

[0046] After confirming that the fault has been cleared, the control unit performs the reclosing operation again, the thyristor T1, the thyristor T4 and the insulated gate bipolar transistor Q1 are turned on, the DC voltage returns to normal, and the DC microgrid resumes operation.

[0047] When the DC terminal P1 is used as input, the DC terminal P2 is used as output, or when the DC terminal P2 is used as input, the DC terminal P1 is used as output, that is, the single-action bidirectional DC solid-state circuit breaker has bidirectional transmission.

[0048] In this embodiment, the input voltage is 500V, where Figure 6 The waveform of the output current i is shown in Figure 1. A short-circuit fault occurs in the line at 1s, and the output current rises rapidly. After rapid blocking by this topology structure, the short-circuit current drops to 0, the fault is blocked, and the faulty line is successfully cut off.

[0049] In this embodiment, Figure 7 A short circuit fault occurs on the line at 1s, and capacitor C1 quickly absorbs the fault current. After rapid blocking by this topology structure, the short-circuit current drops to 0. Then the insulated gate bipolar transistor Q1 is turned on again, and capacitor C1 quickly releases energy, causing the voltage across capacitor C1 to drop to 0, and begins to wait for the next operation.

[0050] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A single-action bidirectional DC solid-state circuit breaker, characterized in that: include: An insulated gate bipolar transistor Q1, a diode D1, a thyristor T1, a thyristor T2, a thyristor T3, a thyristor T4, a varistor MOV1, a control unit, a resistor R1, and a capacitor C1; the collector of the insulated gate bipolar transistor Q1 is connected to the cathodes of the thyristors T1 and T2, and the emitter of the insulated gate bipolar transistor Q1 is connected to the anodes of the thyristors T3 and T4; A cathode of the diode D1 is connected to the collector of the insulated gate bipolar transistor Q1 , and an anode of the diode D1 is connected to the emitter of the insulated gate bipolar transistor Q1 .

2. A single-action bidirectional DC solid-state circuit breaker according to claim 1, characterized in that: The anode of the thyristor T1 and the cathode of the thyristor T3 are connected to the DC terminal P1, the cathode of the thyristor T1 is connected to the cathode of the thyristor T2, the anode of the thyristor T2 and the cathode of the thyristor T4 are connected to the DC terminal P2, and the anode of the thyristor T3 is connected to the anode of the thyristor T4.

3. The single-action bidirectional DC solid-state circuit breaker according to claim 1, characterized in that: The insulated gate bipolar transistor Q1 and the diode D1 form a main switching branch, and the thyristor T1, the thyristor T2, the thyristor T3 and the thyristor T4 form a bidirectional commutation branch.

4. The single-action bidirectional DC solid-state circuit breaker according to claim 1, characterized in that: The insulated gate bipolar transistor Q1 is an N-channel insulated gate bipolar transistor.

5. The single-action bidirectional DC solid-state circuit breaker according to claim 1, characterized in that: The resistor R1 and the capacitor C1 are connected in series and then in parallel with the varistor MOV1. The emitter and collector of the insulated gate bipolar transistor Q1 are connected in parallel with the diode D1. The diode D1 is connected in parallel with the varistor MOV1. The base of the insulated gate bipolar transistor Q1, the thyristor T1, the thyristor T2, the thyristor T3, and the thyristor T4 are all connected to the control unit.

6. The single-action bidirectional DC solid-state circuit breaker according to claim 1, characterized in that: The resistor R1 and the capacitor C1 are connected in series and then in parallel with the varistor MOV1 to form an energy absorption branch for limiting overvoltage and absorbing fault energy.

7. The single-action bidirectional DC solid-state circuit breaker according to claim 1, characterized in that: The resistor R1 and the capacitor C1 form an energy dissipation loop for releasing residual energy stored in the capacitor C1 after fault isolation.

8. A control method for a single-action bidirectional DC solid-state circuit breaker, used to implement the circuit breaker according to any one of claims 1 to 7, characterized in that: The control process includes the following: When the single-action bidirectional DC solid-state circuit breaker is in normal operation, DC terminal P1 is connected to the DC power supply, and DC terminal P2 is connected to the load. The operating current flows from DC terminal P1 through thyristor T1, then through insulated gate bipolar transistor Q1, and finally through thyristor T4 into DC terminal P2, forming a bidirectional conductive main circuit. At this time, insulated gate bipolar transistor Q1 remains in the on state, and thyristors T1 and T4 are kept on by gate signals; varistor MOV1 is in a high-impedance state, and the series branch of resistor R1 and capacitor C1 only acts as a buffer circuit to suppress switching transient overvoltages; When a short circuit occurs at the DC terminal P2, the current in the line increases sharply. The insulated gate bipolar transistor Q1 receives the control instruction from the control unit and immediately turns off. At the same time, the control unit triggers the thyristor T2 and thyristor T3 to turn on, forming a forced commutation path. After the insulated gate bipolar transistor Q1 is turned off, the voltage across it rises rapidly. When the voltage reaches the clamping voltage of the varistor MOV1, the varistor and the energy absorption branch start to work to absorb the short-circuit energy and limit the overvoltage. The fault current gradually decreases under the combined action of the commutation path and the energy absorption branch. When the fault current drops to zero, the thyristors T1 and T4 automatically turn off because the current is less than their holding current, successfully isolating the short-circuit fault. After the fault is isolated, the insulated gate bipolar transistor Q1 remains in the off state, and the energy stored in the capacitor C1 forms a loop through the resistor R1 for release and consumption. When the current of the energy dissipation loop drops to zero, the energy release process of the capacitor C1 ends. After confirming that the fault has been cleared, the control unit performs the reclosing operation again, the thyristor T1, the thyristor T4 and the insulated gate bipolar transistor Q1 are turned on, the DC voltage returns to normal, and the DC microgrid resumes operation.

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