Self-adaptive solid-state circuit breaker and control method thereof

Abstract

The invention provides a self-adaptive solid-state circuit breaker and a control method thereof. The self-adaptive solid-state circuit breaker comprises a main circuit, an upper branch circuit, a lower branch circuit and a buffer circuit. According to the self-adaptive solid-state circuit breaker, the first inductor is arranged in the upper branch circuit, the second inductor is arranged in the lower branch circuit, a direct-current reactor is not directly installed in a direct-current system, switching loss can be reduced, the efficiency and reliability of the system are improved, and meanwhile the circuit is protected against adverse effects caused by the direct-current reactor. In the fault current clearing stage, the first inductor and the second inductor can be adaptively connected to a direct current line, energy stored in the first inductor and the second inductor can be released in the fault current clearing stage, and the buffer circuit can release energy stored in the third inductor and the fourth inductor after tripping in the fault current clearing stage. The current rising rate can be limited, the voltage stress in the disconnection process is reduced, and therefore the fault current clearing speed is effectively increased.

Description

Technical Field

[0001] The present invention relates to the technical field of direct current circuit breakers, and in particular to an adaptive solid-state circuit breaker and a control method thereof. Background Art

[0002] There are three main types of DC circuit breakers, namely mechanical circuit breakers, solid-state circuit breakers and hybrid circuit breakers. Mechanical circuit breakers and hybrid circuit breakers have a slow tripping process and cannot quickly cut off the fault current. Solid-state circuit breakers can switch within a few microseconds, quickly cut off the fault current, and have no moving parts, so there is no arcing or contact corrosion, which is suitable for low-voltage DC systems and medium-voltage DC systems.

[0003] In AC systems, natural zero crossings occur periodically, twice in each cycle. Switching operations near the natural zero crossings can reduce sudden changes in voltage and current, thereby reducing the impact on loads and power supplies. AC circuit breakers can use the appearance of natural zero crossings to complete arc-free extinction, greatly reducing electromagnetic interference and improving power quality. However, in DC systems, since DC current lacks a natural zero crossing, an artificial zero crossing needs to be created, making DC fault isolation a key difficulty.

[0004] With the rapid development of power electronics technology, the application prospects of DC systems based on voltage source converters are gradually broadened due to their ability to provide stable DC voltage sources, network support and flexible control. DC fault current limitation and DC fault isolation are very important for DC systems based on voltage source converters. However, the current DC fault current limiting method requires the direct installation of DC reactors in the DC system, which will have an adverse effect on the normal operation of the system and the rapid isolation of the DC circuit breaker. In addition, there is also the problem of slow fault current clearing speed. Summary of the invention

[0005] The object of the present invention is to provide an adaptive solid-state circuit breaker and a control method thereof, so as to improve the clearing speed of fault current.

[0006] One aspect of the present invention provides an adaptive solid-state circuit breaker, comprising a main circuit, an upper branch circuit, a lower branch circuit and a buffer circuit; The main circuit includes a power supply, an upper H-bridge circuit, a lower H-bridge circuit, a seventh resistor, a third inductor, an eighth resistor, and a fourth inductor. The upper H-bridge circuit is composed of a first diode, a second diode, a third diode, and a fourth diode connected in series in sequence, and the lower H-bridge circuit is composed of a fifth diode, a sixth diode, a seventh diode, and an eighth diode connected in series in sequence. The positive electrode of the power supply is respectively connected to the anode of the first diode and the cathode of the third diode, the negative electrode of the power supply is respectively connected to the anode of the fifth diode and the cathode of the seventh diode, the first end of the seventh resistor is respectively connected to the anode of the second diode and the cathode of the fourth diode, the second end of the seventh resistor is connected to one end of the third inductor, the first end of the eighth resistor is respectively connected to the anode of the sixth diode and the cathode of the eighth diode, and the second end of the eighth resistor is connected to one end of the fourth inductor; One end of the upper branch circuit is connected to the anode of the first diode and the common connection point of the second diode, the other end of the upper branch circuit is connected to the anode of the third diode and the common connection point of the fourth diode, one end of the lower branch circuit is connected to the anode of the fifth diode and the common connection point of the sixth diode, the other end of the lower branch circuit is connected to the anode of the seventh diode and the common connection point of the eighth diode, the upper branch circuit at least includes a first inductor, the lower branch circuit at least includes a second inductor, and the upper branch circuit and the lower branch circuit are respectively used to release the energy stored in the first inductor and the second inductor in the fault current clearing stage; One end of the snubber circuit is connected to the first end of the seventh resistor, the other end of the snubber circuit is connected to the first end of the eighth resistor, the midpoint of the snubber circuit is grounded, and the snubber circuit is used to release the energy stored in the third inductor and the fourth inductor after tripping during the fault current clearing stage.

[0007] The above-mentioned adaptive solid-state circuit breaker, wherein the upper branch circuit includes an upper energy dissipation circuit, a first resistor, a first DC bias power supply and a first IGBT device, the upper energy dissipation circuit includes a first inductor, an eleventh diode and a second resistor, the common point where the cathode of the first diode and the cathode of the second diode are connected is connected to one end of the first resistor, the other end of the first resistor is connected to one end of the first inductor, the anode of the eleventh diode is connected to the second resistor, and the eleventh diode and the second resistor are connected in parallel at both ends of the first inductor; the other end of the first inductor is connected to the negative electrode of the first DC bias power supply, the positive electrode of the first DC bias power supply is connected to the collector of the first IGBT device, and the emitter of the first IGBT device is connected to the common point where the anode of the third diode and the anode of the fourth diode are connected; The lower branch circuit includes a lower energy dissipation circuit, a third resistor, a second DC bias power supply and a second IGBT device. The lower energy dissipation circuit includes a second inductor, a twelfth diode and a fourth resistor. The common point where the cathode of the fifth diode is connected to the cathode of the sixth diode is connected to one end of the third resistor, the other end of the third resistor is connected to one end of the second inductor, the anode of the twelfth diode is connected to the fourth resistor, and the twelfth diode and the fourth resistor are connected in parallel at both ends of the second inductor; the other end of the second inductor is connected to the negative electrode of the second DC bias power supply, the positive electrode of the second DC bias power supply is connected to the collector of the second IGBT device, and the emitter of the second IGBT device is connected to the common point where the anode of the seventh diode is connected to the anode of the eighth diode.

[0008] The above-mentioned adaptive solid-state circuit breaker, wherein the snubber circuit includes a ninth diode, a fifth resistor, a sixth resistor, and a tenth diode, the cathode of the ninth diode is connected to the first end of the seventh resistor, the anode of the ninth diode is connected to one end of the fifth resistor, the other end of the fifth resistor is grounded and connected to one end of the sixth resistor, the other end of the sixth resistor is connected to the cathode of the tenth diode, and the anode of the tenth diode is connected to the first end of the eighth resistor.

[0009] In the above-mentioned adaptive solid-state circuit breaker, the resistance value of the first resistor is equal to the resistance value of the third resistor, the resistance value of the second resistor is equal to the resistance value of the fourth resistor, the resistance value of the fifth resistor is equal to the resistance value of the sixth resistor, the resistance value of the seventh resistor is equal to the resistance value of the eighth resistor, the inductance value of the first inductor is equal to the inductance value of the second inductor, the inductance value of the third inductor is equal to the inductance value of the fourth inductor, and the voltage value of the first DC bias power supply is equal to the voltage value of the second DC bias power supply.

[0010] Another aspect of the present invention provides a control method for the above-mentioned adaptive solid-state circuit breaker, comprising: (1) When in normal working state, the first IGBT device and the second IGBT device are in the on state, and the bias current i provided by the first DC bias power supply and the second DC bias power supply is b Greater than the DC line current i dc , so that the upper branch circuit and the lower branch circuit are bypassed relative to the main circuit, and the diodes in the upper H-bridge circuit and the diodes in the lower H-bridge circuit are both in the on state; In the upper H-bridge circuit, the inductor current i of the first inductor is L1 The flow path is: the positive electrode of the first DC bias power supply, the first IGBT device, the third diode and the fourth diode, the first diode and the second diode, the first resistor, the first inductor, and the negative electrode of the first DC bias power supply; In the lower H-bridge circuit, the inductor current i of the second inductor is L2The flow path is: the positive electrode of the second DC bias power supply, the second IGBT device, the seventh diode and the eighth diode, the fifth diode and the sixth diode, the third resistor, the second inductor, and the negative electrode of the second DC bias power supply; DC line current i dc The flow path is: the positive electrode of the power supply, the first diode and the third diode, the second diode and the fourth diode, the seventh resistor, the third inductor, the fourth inductor, the eighth resistor, the sixth diode and the eighth diode, the fifth diode and the seventh diode, and the negative electrode of the power supply; (2) When in the fault current limiting state, when the DC line current i dc Increase to i b When the second diode and the third diode are turned off in the upper H-bridge circuit, the DC line current automatically commutates and flows through the first diode, the upper branch circuit, and the fourth diode in sequence; in the lower H-bridge circuit, the fifth diode and the eighth diode are turned off, and the DC line current automatically commutates and flows through the sixth diode, the lower branch circuit, and the seventh diode in sequence; The inductor current i of the first inductor L1 , the inductor current i of the second inductor L2 and the DC line current i dc The flow paths are the same, and the flow paths are: the positive electrode of the power supply, the first diode, the first resistor, the first inductor, the first DC bias power supply, the first IGBT device, the seventh resistor, the third inductor, the fourth inductor, the eighth resistor, the sixth diode, the third resistor, the second inductor, the second DC bias power supply, the second IGBT device, the seventh diode, and the negative electrode of the power supply; (3) When in the fault current clearing state, the first IGBT device and the second IGBT device are turned off. As the fault current in the line decreases, the inductance in the line generates a reverse electromotive force to release energy. The first inductor and the second inductor dissipate energy through the upper energy dissipation circuit and the lower energy dissipation circuit respectively. The third inductor and the fourth inductor in the DC line dissipate energy through the fifth resistor and the sixth resistor in the snubber circuit until the fault current is cleared. In the upper H-bridge circuit, the inductor current i of the first inductor is L1 The flow path is: the first inductor, the second resistor, the eleventh diode, the first inductor; In the lower H-bridge circuit, the inductor current i of the second inductor is L2 The flow path is: the second inductor, the fourth resistor, the twelfth diode, the second inductor; The flow path of the inductor current of the DC line is: the seventh resistor, the third inductor, the fourth inductor, the eighth resistor, the tenth diode, the sixth resistor, the fifth resistor, the ninth diode, and the seventh resistor; (4) When in the recovery state, when the follow-on current of the first inductor and the second inductor drops to 0, the first IGBT device and the second IGBT device are immediately closed to restore the bias current, the upper branch circuit and the lower branch circuit are bypassed again, and the adaptive solid-state circuit breaker gradually returns to a normal working state.

[0011] The adaptive solid-state circuit breaker and control method thereof provided by the present invention have the following beneficial effects: (1) The adaptive solid-state circuit breaker of the present invention can reduce switching losses, improve system efficiency and reliability, and protect the circuit from adverse effects of the DC reactor by setting a first inductor in the upper branch circuit and a second inductor in the lower branch circuit instead of directly installing a DC reactor in the DC system; (2) In the fault current clearing stage, the first inductor in the upper branch circuit and the second inductor in the lower branch circuit of the adaptive solid-state circuit breaker of the present invention can be adaptively connected to the DC line, and can release the energy stored in the first inductor and the second inductor in the fault current clearing stage, and the buffer circuit can release the energy stored in the third inductor and the fourth inductor after tripping in the fault current clearing stage, which can limit the current rising rate and reduce the voltage stress during the disconnection process, thereby effectively accelerating the fault current clearing speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A schematic diagram of the circuit structure of the adaptive solid-state circuit breaker provided by the present invention; Figure 2 A working principle diagram of the adaptive solid-state circuit breaker provided by the present invention when it is in a normal working state; Figure 3 A working principle diagram of the adaptive solid-state circuit breaker provided by the present invention when it is in a fault current limiting state; Figure 4 A working principle diagram of the adaptive solid-state circuit breaker provided by the present invention when it is in a fault current clearing state; Figure 5 It is a simulation waveform diagram of the adaptive solid-state circuit breaker of the present invention; Figure 6 It is a simulation waveform diagram of the mutual inductance current limiter in the prior art. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] See also Figures 1 to 4 An embodiment of the present invention provides an adaptive solid-state circuit breaker, including a main circuit, an upper branch circuit, a lower branch circuit and a buffer circuit.

[0015] The main circuit includes a power supply U DC , an upper H-bridge circuit, a lower H-bridge circuit, a seventh resistor R7, a third inductor L3, an eighth resistor R8, and a fourth inductor L4.

[0016] The upper H-bridge circuit is composed of a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4 connected in series in sequence, and the lower H-bridge circuit is composed of a fifth diode D5, a sixth diode D6, a seventh diode D7, and an eighth diode D8 connected in series in sequence.

[0017] Power supply DC The positive electrode is connected to the anode of the first diode D1 and the cathode of the third diode D3 respectively, and the power supply U DC The negative electrode of the eighth resistor R8 is respectively connected to the anode of the sixth diode D6 and the cathode of the eighth diode D8, and the second end of the eighth resistor R8 is connected to one end of the fourth inductor L4.

[0018] It should be noted that, under normal circumstances, the other end of the third inductor L3 and the other end of the fourth inductor L4 are connected to the load. When a short circuit occurs, the other end of the third inductor L3 is connected to the other end of the fourth inductor L4.

[0019] One end of the upper branch circuit is connected to the anode of the first diode D1 and the common connection point of the second diode D2, the other end of the upper branch circuit is connected to the anode of the third diode D3 and the common connection point of the fourth diode D4, one end of the lower branch circuit is connected to the anode of the fifth diode D5 and the common connection point of the sixth diode D6, the other end of the lower branch circuit is connected to the anode of the seventh diode D7 and the common connection point of the eighth diode D8, the upper branch circuit at least includes a first inductor L1, the lower branch circuit at least includes a second inductor L2, and the upper branch circuit and the lower branch circuit are respectively used to release the energy stored in the first inductor L1 and the second inductor L2 in the fault current clearing stage.

[0020] One end of the snubber circuit is connected to the first end of the seventh resistor R7, the other end of the snubber circuit is connected to the first end of the eighth resistor R8, and the midpoint of the snubber circuit is grounded to ensure uniform voltage distribution and enable the snubber circuit to operate normally during both pole-to-pole faults and pole-to-ground faults. The snubber circuit is used to release the energy stored in the third inductor L3 and the fourth inductor L4 after tripping during the fault current clearing stage.

[0021] Specifically, the upper branch circuit includes an upper energy dissipation circuit, a first resistor R1, a first DC bias power supply U b1 and the first IGBT device S1, the upper energy dissipation circuit includes a first inductor L1, an eleventh diode D11 and a second resistor R2, the common point where the cathode of the first diode D1 and the cathode of the second diode D2 are connected is connected to one end of the first resistor R1, the other end of the first resistor R1 is connected to one end of the first inductor L1, the anode of the eleventh diode D11 is connected to the second resistor R2, and the eleventh diode D11 and the second resistor R2 are connected in parallel at both ends of the first inductor L1; the other end of the first inductor L1 is connected to the first DC bias power supply U b1 The negative pole of the first DC bias power supply U b1 The anode of the diode D1 is connected to the collector of the first IGBT device S1, and the emitter of the first IGBT device S1 is connected to a common point where the anode of the third diode D3 and the anode of the fourth diode D4 are connected.

[0022] The lower branch circuit includes a lower energy dissipation circuit, a third resistor R3, a second DC bias power supply U b2 and the second IGBT device S2, the lower energy dissipation circuit includes a second inductor L2, a twelfth diode D12 and a fourth resistor R4, a common point where the cathode of the fifth diode D5 and the cathode of the sixth diode D6 are connected is connected to one end of the third resistor R3, the other end of the third resistor R3 is connected to one end of the second inductor L2, the anode of the twelfth diode D12 is connected to the fourth resistor R4, and the twelfth diode D12 and the fourth resistor R4 are connected in parallel at both ends of the second inductor L2; the other end of the second inductor L2 is connected to the second DC bias power supply U b2 The negative pole of the second DC bias power supply U b2 The anode of the diode D7 is connected to the collector of the second IGBT device S2, and the emitter of the second IGBT device S2 is connected to a common point where the anode of the seventh diode D7 and the anode of the eighth diode D8 are connected.

[0023] Specifically, the buffer circuit includes a ninth diode D9, a fifth resistor R5, a sixth resistor R6, and a tenth diode D10, the cathode of the ninth diode D9 is connected to the first end of the seventh resistor R7, the anode of the ninth diode D9 is connected to one end of the fifth resistor R5, the other end of the fifth resistor R5 is grounded and connected to one end of the sixth resistor R6, the other end of the sixth resistor R6 is connected to the cathode of the tenth diode D10, and the anode of the tenth diode D10 is connected to the first end of the eighth resistor R8.

[0024] In this embodiment, the resistance value of the first resistor R1 is equal to the resistance value of the third resistor R3, the resistance value of the second resistor R2 is equal to the resistance value of the fourth resistor R4, the resistance value of the fifth resistor R5 is equal to the resistance value of the sixth resistor R6, the resistance value of the seventh resistor R7 is equal to the resistance value of the eighth resistor R8, the inductance value of the first inductor L1 is equal to the inductance value of the second inductor L2, the inductance value of the third inductor L3 is equal to the inductance value of the fourth inductor L4, and the first DC bias power supply U b1 The voltage value of the second DC bias power supply U b2 The voltage values ​​are equal.

[0025] An embodiment of the present invention further provides a control method for the above-mentioned adaptive solid-state circuit breaker, comprising: (1) Please pay special attention to Figure 2 When in normal working state, the first IGBT device S1 and the second IGBT device S2 are in the on state, and the first DC bias power supply U b1 and the second DC bias power supply U b2 The bias current provided by b Greater than the DC line current i dc , so that the upper branch circuit and the lower branch circuit are bypassed relative to the main circuit, and the diodes in the upper H-bridge circuit and the diodes in the lower H-bridge circuit are both in the on state; In the upper H-bridge circuit, the inductor current i of the first inductor L1 is L1 The flow paths are as follows: the first DC bias power supply U b1 The positive electrode, the first IGBT device S1, the third diode D3 and the fourth diode D4, the first diode D1 and the second diode D2, the first resistor R1, the first inductor L1, the first DC bias power supply U b1 The negative electrode; In the lower H-bridge circuit, the inductor current i of the second inductor L2 is L2 The flow paths are as follows: The second DC bias power supply U b2 The positive electrode, the second IGBT device S2, the seventh diode D7 and the eighth diode D8, the fifth diode D5 and the sixth diode D6, the third resistor R3, the second inductor L2, the second DC bias power supply U b2 The negative electrode; DC line current i dc The flow paths are: power supply U DC The positive electrode of the first diode D1 and the third diode D3, the second diode D2 and the fourth diode D4, the seventh resistor R7, the third inductor L3, the fourth inductor L4, the eighth resistor R8, the sixth diode D6 and the eighth diode D8, the fifth diode D5 and the seventh diode D7, the power supply U DC of the negative electrode.

[0026] In addition, in this embodiment, the upper H-bridge circuit includes a first bridge arm, a second bridge arm, a third bridge arm, and a fourth bridge arm, the first bridge arm includes a first diode D1, the second bridge arm includes a second diode D2, the third bridge arm includes a third diode D3, and the fourth bridge arm includes a fourth diode D4; When in normal working state, the adaptive solid-state circuit breaker satisfies the following equation: ; ; ; ; Among them, i1, i2, i3, and i4 are the currents of the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm respectively.

[0027] i dc If i1 and i4 are greater than 0, then to ensure that the branch circuit is bypassed relative to the main circuit under normal working conditions, the second diode D2 and the third diode D3 should be turned on, that is, i2 and i3 are greater than 0, and the bias current i b Greater than the DC line current i dc , the diodes of the four bridge arms are all in the on state.

[0028] (2) Please pay special attention to Figure 3 , when in the fault current limiting state, the DC line current i dc The fault current starts to increase, where the rate of increase is limited by the first inductor L1 and the second inductor L2. dc Increase to i b When , i2 and i3 decrease to 0, in the upper H-bridge circuit, the second diode D2 and the third diode D3 are turned off, and the DC line current automatically commutates and flows through the first diode D1, the upper branch circuit, and the fourth diode D4 in sequence; in the lower H-bridge circuit, the fifth diode D5 and the eighth diode D8 are turned off, and the DC line current automatically commutates and flows through the sixth diode D6, the lower branch circuit, and the seventh diode D7 in sequence.

[0029] The inductor current i of the first inductor L1 L1 , the inductor current i of the second inductor L2L2 and the DC line current i dc The flow paths are the same, and the flow paths are: power supply U DC The positive electrode, the first diode D1, the first resistor R1, the first inductor L1, the first DC bias power supply U b1 , a first IGBT device S1, a seventh resistor R7, a third inductor L3, a fourth inductor L4, an eighth resistor R8, a sixth diode D6, a third resistor R3, a second inductor L2, a second DC bias power supply U b2 , the second IGBT device S2, the seventh diode D7, the power supply U DC of the negative electrode.

[0030] (3) Please pay special attention to Figure 4 When the fault current is cleared, a trip signal is given to the first IGBT device S1 and the second IGBT device S2, and the first IGBT device S1 and the second IGBT device S2 are turned off. As the fault current in the line decreases, the inductance in the line generates a reverse electromotive force to release energy. The first inductor L1 and the second inductor L2 dissipate energy through the upper energy dissipation circuit and the lower energy dissipation circuit respectively. Specifically, the second resistor R2 and the fourth resistor R4 are used to absorb the dissipated energy of the first inductor L1 and the second inductor L2. The third inductor L3 and the fourth inductor L4 in the DC line dissipate energy through the fifth resistor R5 and the sixth resistor R6 in the buffer circuit until the fault current is cleared. dc =0; In the upper H-bridge circuit, the inductor current i of the first inductor L1 is L1 The flow path is: the first inductor L1, the second resistor R2, the eleventh diode D11, the first inductor L1; In the lower H-bridge circuit, the inductor current i of the second inductor L2 is L2 The flow path is: the second inductor L2, the fourth resistor R4, the twelfth diode D12, and the second inductor L2; The flow path of the DC line inductor current is: the seventh resistor R7, the third inductor L3, the fourth inductor L4, the eighth resistor R8, the tenth diode D10, the sixth resistor R6, the fifth resistor R5, the ninth diode D9, and the seventh resistor R7.

[0031] (4) When in the recovery state, when the follow-on current of the first inductor L1 and the second inductor L2 drops to 0, the first IGBT device S1 and the second IGBT device S2 are immediately closed to restore the bias current, the upper branch circuit and the lower branch circuit are bypassed again, and the adaptive solid-state circuit breaker gradually returns to a normal working state.

[0032] The above adaptive solid-state circuit breaker was simulated and verified. Taking the PP fault of 6.5kV DC transmission line as an example, the simulation experiment was carried out using MATLAB software. The resistance values ​​of the first resistor R1 and the third resistor R3 are set to 0.01Ω, the resistance values ​​of the second resistor R2, the fourth resistor R4, the seventh resistor R7 and the eighth resistor R8 are set to 1Ω, the resistance values ​​of the fifth resistor R5 and the sixth resistor R6 are set to 10Ω, the inductance values ​​of the first inductor L1 and the second inductor L2 are set to 0.025mH, the inductance values ​​of the third inductor L3 and the fourth inductor L4 are set to 0.0005mH, and the obtained simulation waveform is shown in the figure below. Figure 5 At the same time, the mutual inductance current limiter in the prior art is used for simulation verification, and the obtained simulation waveform is as shown in Figure 6 shown.

[0033] contrast Figure 5 and Figure 6 It can be seen that, compared with the mutual inductance current limiter, the fault clearing time of the adaptive solid-state circuit breaker of the present invention is greatly shortened, the fault current clearing speed is faster, and it is more in line with the requirement for rapid action of the DC circuit breaker.

[0034] In summary, the adaptive solid-state circuit breaker and control method thereof provided by the present invention have the following beneficial effects: (1) The adaptive solid-state circuit breaker of the present invention can reduce switching losses, improve system efficiency and reliability, and protect the circuit from adverse effects of the DC reactor by setting a first inductor in the upper branch circuit and a second inductor in the lower branch circuit instead of directly installing a DC reactor in the DC system; (2) In the fault current clearing stage, the first inductor in the upper branch circuit and the second inductor in the lower branch circuit of the adaptive solid-state circuit breaker of the present invention can be adaptively connected to the DC line, and can release the energy stored in the first inductor and the second inductor in the fault current clearing stage, and the buffer circuit can release the energy stored in the third inductor and the fourth inductor after tripping in the fault current clearing stage, which can limit the current rising rate and reduce the voltage stress during the disconnection process, thereby effectively accelerating the fault current clearing speed.

[0035] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0036] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. An adaptive solid-state circuit breaker, characterized in that: It includes a main circuit, an upper branch circuit, a lower branch circuit and a buffer circuit; The main circuit includes a power supply, an upper H-bridge circuit, a lower H-bridge circuit, a seventh resistor, a third inductor, an eighth resistor, and a fourth inductor. The upper H-bridge circuit is composed of a first diode, a second diode, a third diode, and a fourth diode connected in series in sequence, and the lower H-bridge circuit is composed of a fifth diode, a sixth diode, a seventh diode, and an eighth diode connected in series in sequence. The positive electrode of the power supply is respectively connected to the anode of the first diode and the cathode of the third diode, the negative electrode of the power supply is respectively connected to the anode of the fifth diode and the cathode of the seventh diode, the first end of the seventh resistor is respectively connected to the anode of the second diode and the cathode of the fourth diode, the second end of the seventh resistor is connected to one end of the third inductor, the first end of the eighth resistor is respectively connected to the anode of the sixth diode and the cathode of the eighth diode, and the second end of the eighth resistor is connected to one end of the fourth inductor; One end of the upper branch circuit is connected to the anode of the first diode and the common connection point of the second diode, the other end of the upper branch circuit is connected to the anode of the third diode and the common connection point of the fourth diode, one end of the lower branch circuit is connected to the anode of the fifth diode and the common connection point of the sixth diode, the other end of the lower branch circuit is connected to the anode of the seventh diode and the common connection point of the eighth diode, the upper branch circuit at least includes a first inductor, the lower branch circuit at least includes a second inductor, and the upper branch circuit and the lower branch circuit are respectively used to release the energy stored in the first inductor and the second inductor in the fault current clearing stage; One end of the snubber circuit is connected to the first end of the seventh resistor, the other end of the snubber circuit is connected to the first end of the eighth resistor, the midpoint of the snubber circuit is grounded, and the snubber circuit is used to release the energy stored in the third inductor and the fourth inductor after tripping during the fault current clearing stage.

2. The adaptive solid-state circuit breaker according to claim 1, characterized in that: The upper branch circuit includes an upper energy dissipation circuit, a first resistor, a first DC bias power supply and a first IGBT device. The upper energy dissipation circuit includes a first inductor, an eleventh diode and a second resistor. The common point where the cathode of the first diode and the cathode of the second diode are connected is connected to one end of the first resistor, the other end of the first resistor is connected to one end of the first inductor, the anode of the eleventh diode is connected to the second resistor, and the eleventh diode and the second resistor are connected in parallel at both ends of the first inductor; the other end of the first inductor is connected to the negative electrode of the first DC bias power supply, the positive electrode of the first DC bias power supply is connected to the collector of the first IGBT device, and the emitter of the first IGBT device is connected to the common point where the anode of the third diode and the anode of the fourth diode are connected; The lower branch circuit includes a lower energy dissipation circuit, a third resistor, a second DC bias power supply and a second IGBT device. The lower energy dissipation circuit includes a second inductor, a twelfth diode and a fourth resistor. The common point where the cathode of the fifth diode is connected to the cathode of the sixth diode is connected to one end of the third resistor, the other end of the third resistor is connected to one end of the second inductor, the anode of the twelfth diode is connected to the fourth resistor, and the twelfth diode and the fourth resistor are connected in parallel at both ends of the second inductor; the other end of the second inductor is connected to the negative electrode of the second DC bias power supply, the positive electrode of the second DC bias power supply is connected to the collector of the second IGBT device, and the emitter of the second IGBT device is connected to the common point where the anode of the seventh diode is connected to the anode of the eighth diode.

3. The adaptive solid-state circuit breaker according to claim 2, characterized in that: The buffer circuit includes a ninth diode, a fifth resistor, a sixth resistor, and a tenth diode, wherein the cathode of the ninth diode is connected to the first end of the seventh resistor, the anode of the ninth diode is connected to one end of the fifth resistor, the other end of the fifth resistor is grounded and connected to one end of the sixth resistor, the other end of the sixth resistor is connected to the cathode of the tenth diode, and the anode of the tenth diode is connected to the first end of the eighth resistor.

4. The adaptive solid-state circuit breaker according to claim 3, characterized in that: The resistance value of the first resistor is equal to the resistance value of the third resistor, the resistance value of the second resistor is equal to the resistance value of the fourth resistor, the resistance value of the fifth resistor is equal to the resistance value of the sixth resistor, the resistance value of the seventh resistor is equal to the resistance value of the eighth resistor, the inductance value of the first inductor is equal to the inductance value of the second inductor, the inductance value of the third inductor is equal to the inductance value of the fourth inductor, and the voltage value of the first DC bias power supply is equal to the voltage value of the second DC bias power supply.

5. The control method of the adaptive solid-state circuit breaker according to claim 4, characterized in that: include: (1) When in normal working state, the first IGBT device and the second IGBT device are in the on state, and the bias current i provided by the first DC bias power supply and the second DC bias power supply is b Greater than the DC line current i dc , so that the upper branch circuit and the lower branch circuit are bypassed relative to the main circuit, and the diodes in the upper H-bridge circuit and the diodes in the lower H-bridge circuit are both in the on state; In the upper H-bridge circuit, the inductor current i of the first inductor is L1 The flow path is: the positive electrode of the first DC bias power supply, the first IGBT device, the third diode and the fourth diode, the first diode and the second diode, the first resistor, the first inductor, and the negative electrode of the first DC bias power supply; In the lower H-bridge circuit, the inductor current i of the second inductor is L2 The flow path is: the positive electrode of the second DC bias power supply, the second IGBT device, the seventh diode and the eighth diode, the fifth diode and the sixth diode, the third resistor, the second inductor, and the negative electrode of the second DC bias power supply; DC line current i dc The flow path is: the positive electrode of the power supply, the first diode and the third diode, the second diode and the fourth diode, the seventh resistor, the third inductor, the fourth inductor, the eighth resistor, the sixth diode and the eighth diode, the fifth diode and the seventh diode, and the negative electrode of the power supply; (2) When in the fault current limiting state, when the DC line current i dc Increase to i b When the second diode and the third diode are turned off in the upper H-bridge circuit, the DC line current automatically commutates and flows through the first diode, the upper branch circuit, and the fourth diode in sequence; in the lower H-bridge circuit, the fifth diode and the eighth diode are turned off, and the DC line current automatically commutates and flows through the sixth diode, the lower branch circuit, and the seventh diode in sequence; The inductor current i of the first inductor L1 , the inductor current i of the second inductor L2 and the DC line current i dc The flow paths are the same, and the flow paths are: the positive electrode of the power supply, the first diode, the first resistor, the first inductor, the first DC bias power supply, the first IGBT device, the seventh resistor, the third inductor, the fourth inductor, the eighth resistor, the sixth diode, the third resistor, the second inductor, the second DC bias power supply, the second IGBT device, the seventh diode, and the negative electrode of the power supply; (3) When in the fault current clearing state, the first IGBT device and the second IGBT device are turned off. As the fault current in the line decreases, the inductance in the line generates a reverse electromotive force to release energy. The first inductor and the second inductor dissipate energy through the upper energy dissipation circuit and the lower energy dissipation circuit respectively. The third inductor and the fourth inductor in the DC line dissipate energy through the fifth resistor and the sixth resistor in the snubber circuit until the fault current is cleared. In the upper H-bridge circuit, the inductor current i of the first inductor is L1 The flow path is: the first inductor, the second resistor, the eleventh diode, the first inductor; In the lower H-bridge circuit, the inductor current i of the second inductor is L2 The flow path is: the second inductor, the fourth resistor, the twelfth diode, the second inductor; The flow path of the inductor current of the DC line is: the seventh resistor, the third inductor, the fourth inductor, the eighth resistor, the tenth diode, the sixth resistor, the fifth resistor, the ninth diode, and the seventh resistor; (4) When in the recovery state, when the follow-on current of the first inductor and the second inductor drops to 0, the first IGBT device and the second IGBT device are immediately closed to restore the bias current, the upper branch circuit and the lower branch circuit are bypassed again, and the adaptive solid-state circuit breaker gradually returns to a normal working state.

6. The control method of the adaptive solid-state circuit breaker according to claim 5, characterized in that: The upper H-bridge circuit includes a first bridge arm, a second bridge arm, a third bridge arm, and a fourth bridge arm, wherein the first bridge arm includes a first diode, the second bridge arm includes a second diode, the third bridge arm includes a third diode, and the fourth bridge arm includes a fourth diode; When in normal working state, the adaptive solid-state circuit breaker satisfies the following equation: ； ； ； ； Among them, i1, i2, i3, and i4 are the currents of the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm respectively.

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