Bypass coupling direct-current circuit breaker and control method of bypass coupling direct-current circuit breaker

Abstract

The embodiment of the invention provides a bypass coupling direct-current circuit breaker and a control method of the bypass coupling direct-current circuit breaker, and is applied to the technical field of direct-current circuit breakers. The circuit breaker comprises a coupling inductor primary side, a coupling inductor secondary side, an energy storage capacitor, a commutation inductor, an insulated gate bipolar transistor, a mechanical switch and an energy consumption branch. The synonym terminal of the primary side of the coupling inductor is connected with the direct current system, the dotted terminal of the primary side of the coupling inductor is connected with the synonym terminal of the secondary side of the coupling inductor, and the dotted terminal of the secondary side of the coupling inductor is connected with the mechanical switch; the secondary side of the coupling inductor is connected in parallel with the insulated gate bipolar transistor and then connected in series with the mechanical switch to form a main branch; the energy storage capacitor and the commutation inductor are connected in series to form a commutation branch, and the commutation branch is connected in parallel with the main branch; and the energy consumption branch is connected in parallel with the main branch and the commutation branch. The technical effect of improving the capacitor charging efficiency is achieved.

Description

Technical Field

[0001] This application relates to the field of DC circuit breaker technology, and in particular to a bypass-coupled DC circuit breaker and a control method for the bypass-coupled DC circuit breaker. Background Technology

[0002] With the rapid growth of installed capacity of renewable energy sources such as wind power and photovoltaics, DC transmission systems have become a key technological path for realizing large-scale cross-regional transmission of new energy. In flexible DC transmission systems, DC circuit breakers, as core protection devices, undertake key functions such as rapid fault isolation and system topology reconfiguration.

[0003] Existing mechanical high-voltage DC circuit breakers typically use large-capacity energy storage capacitors as the energy source for fault current transfer. The circuit breaker operates as follows: during normal operation, system current flows through the main branch; when a fault is detected, the control system triggers the mechanical switch to open, and the fault current is transferred from the mechanical switch to the energy-consuming branch through an oscillating circuit formed by the energy storage capacitor and inductor.

[0004] Because the charging process of energy storage capacitors in the prior art relies on the energy transfer of external power sources or large capacitor devices, and the energy distribution between capacitors is affected by a variety of factors, there is a technical problem of low capacitor charging efficiency in the prior art. Summary of the Invention

[0005] This application provides a bypass-coupled DC circuit breaker and a control method for the bypass-coupled DC circuit breaker, in order to achieve the technical effect of improving capacitor charging efficiency.

[0006] In a first aspect, embodiments of this application provide a bypass coupled DC circuit breaker, comprising: a primary side of a coupling inductor, a secondary side of a coupling inductor, an energy storage capacitor, a commutation inductor, an insulated gate bipolar transistor, a mechanical switch, and an energy dissipation branch;

[0007] The opposite-named terminal of the primary side of the coupled inductor is connected to the DC system, the same-named terminal of the primary side of the coupled inductor is connected to the opposite-named terminal of the secondary side of the coupled inductor, and the same-named terminal of the secondary side of the coupled inductor is connected to the mechanical switch.

[0008] The secondary side of the coupled inductor is connected in parallel with the insulated gate bipolar transistor and then connected in series with the mechanical switch to form the main branch;

[0009] The energy storage capacitor and the commutation inductor are connected in series to form the commutation branch, and the commutation branch is connected in parallel with the main branch.

[0010] The energy-consuming branch is connected in parallel with the main branch and the converter branch;

[0011] The mutual inductance between the primary and secondary sides of the coupled inductor is used to adjust the charging path of the energy storage capacitor when the mechanical switch is disconnected; the commutation branch is used to provide oscillating current during the fault current transfer process, causing the mechanical switch current to cross zero to achieve arc extinction.

[0012] In one possible implementation, the energy-dissipating branch includes a surge arrester;

[0013] The surge arrester is connected in parallel with the main branch and the converter branch to form an energy-dissipating branch;

[0014] Among them, the surge arrester is used to switch to a low-resistance state after the fault current is transferred to the converter branch and the voltage across its terminals reaches the preset operating voltage in order to absorb the remaining fault energy of the system and avoid overvoltage damage to the components.

[0015] In one possible implementation, the primary and secondary sides of the coupled inductor adopt a multi-winding structure, which includes at least two windings. The turns ratio of each winding is adjusted within a preset range. The windings are arranged in a layered or concentric manner to adapt to the current limiting requirements of different DC systems.

[0016] In one possible implementation, when the circuit breaker is in normal operation, the current of the DC system flows through the primary side of the coupled inductor, the secondary side of the coupled inductor, and the mechanical switch. At this time, there is no mutual inductance between the primary and secondary sides of the coupled inductor, the insulated gate bipolar transistor is in the open state, and no current flows through the commutation branch and the energy dissipation branch.

[0017] In one possible implementation, when the circuit breaker is in the current transfer phase and the contacts of the mechanical switch are separated to the rated opening distance, the insulated gate bipolar transistor closes; the mechanical switch, the insulated gate bipolar transistor, the energy storage capacitor, and the commutation inductor form a closed loop, and the energy storage capacitor and the commutation inductor generate a high-frequency oscillating current in the closed loop.

[0018] In one possible implementation, when the circuit breaker is in the energy absorption phase and the voltage across the surge arrester reaches its preset operating voltage, the surge arrester switches to the working state.

[0019] When the surge arrester is in operation, it converts fault energy into heat energy dissipation through its nonlinear resistance characteristics, while limiting the voltage across the mechanical switch to below a first preset threshold to prevent insulation breakdown of the mechanical switch.

[0020] In a second aspect, embodiments of this application provide a control method for a bypass-coupled DC circuit breaker, applied to the bypass-coupled DC circuit breaker in the first aspect, the method comprising:

[0021] The voltage value of the energy storage capacitor in the bypass coupled DC circuit breaker and the main branch current of the bypass coupled DC circuit breaker are collected in real time; the main branch current includes the normal current during the normal operation phase and the fault current during the current transfer phase.

[0022] Adjusting the closing timing of the insulated gate bipolar transistor in the bypass-coupled DC circuit breaker based on voltage value;

[0023] The energy distribution ratio in the bypass coupled DC circuit breaker is adjusted based on the main branch current; where the energy distribution ratio refers to the input ratio of the energy storage capacitor in the bypass coupled DC circuit breaker.

[0024] In one possible implementation, adjusting the closing timing of the insulated-gate bipolar transistor in the bypass-coupled DC circuit breaker based on the voltage value includes:

[0025] Continuously determine whether the voltage value of the energy storage capacitor obtained in real time reaches the second preset threshold;

[0026] At the same time, determine whether the contacts of the mechanical switch in the bypass coupling DC circuit breaker have separated to the rated opening distance;

[0027] When the mechanical switch contacts separate to the rated opening distance and the energy storage capacitor voltage reaches the second preset threshold, a closing command is sent to the insulated gate bipolar transistor to control its closing.

[0028] The second preset threshold is the voltage threshold that ensures the energy storage capacitor and the commutation inductor generate the maximum peak high-frequency oscillation current.

[0029] In one possible implementation, adjusting the energy distribution ratio in the bypass-coupled DC circuit breaker based on the main branch current includes:

[0030] After the insulated gate bipolar transistor is closed, the zero-crossing state of the main branch current is monitored in real time.

[0031] When a zero-crossing point is detected in the main branch current, the energy distribution ratio is adjusted to reduce the energy input from the coupling inductor to the energy storage capacitor in the bypass coupled DC circuit breaker.

[0032] Thirdly, embodiments of this application provide a control device for a bypass-coupled DC circuit breaker, applied to the bypass-coupled DC circuit breaker in the first aspect, the device comprising:

[0033] The acquisition module is used to collect the voltage value of the energy storage capacitor in the bypass coupled DC circuit breaker in real time, as well as the main branch current of the bypass coupled DC circuit breaker; wherein, the main branch current includes the normal current during the normal operation phase and the fault current during the current transfer phase.

[0034] The first processing module is used to adjust the closing timing of the insulated gate bipolar transistor in the bypass coupled DC circuit breaker based on the voltage value;

[0035] The second processing module is used to adjust the energy distribution ratio in the bypass coupled DC circuit breaker based on the main branch current; wherein, the energy distribution ratio refers to the input ratio of the energy storage capacitor in the bypass coupled DC circuit breaker.

[0036] In one possible implementation, the first processing module is further configured to:

[0037] Continuously determine whether the voltage value of the energy storage capacitor obtained in real time reaches the second preset threshold;

[0038] At the same time, determine whether the contacts of the mechanical switch in the bypass coupling DC circuit breaker have separated to the rated opening distance;

[0039] When the mechanical switch contacts separate to the rated opening distance and the energy storage capacitor voltage reaches the second preset threshold, a closing command is sent to the insulated gate bipolar transistor to control its closing.

[0040] The second preset threshold is the voltage threshold that ensures the energy storage capacitor and the commutation inductor generate the maximum peak high-frequency oscillation current.

[0041] In one possible implementation, the second processing module is further configured to:

[0042] After the insulated gate bipolar transistor is closed, the zero-crossing state of the main branch current is monitored in real time.

[0043] When a zero-crossing point is detected in the main branch current, the energy distribution ratio is adjusted to reduce the energy input from the coupling inductor to the energy storage capacitor in the bypass coupled DC circuit breaker.

[0044] Fourthly, embodiments of this application provide an electronic device, including: a memory and a processor;

[0045] The memory stores the instructions that the computer executes;

[0046] The processor executes computer execution instructions stored in memory, causing the processor to perform the second aspect above and various possible implementations thereof.

[0047] Fifthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the second aspect above and various possible implementations of the second aspect.

[0048] In a sixth aspect, embodiments of this application provide a computer program product, including a computer program that, when executed by a processor, implements the second aspect as described above and various possible implementations of the second aspect.

[0049] This application provides a bypass-coupled DC circuit breaker and a control method for it. The DC circuit breaker includes a primary side of a coupling inductor, a secondary side of a coupling inductor, an energy storage capacitor, a commutator inductor, an insulated-gate bipolar transistor (IGBT), a mechanical switch, and a power dissipation branch. The primary side of the coupling inductor is connected to the DC system via a different-name terminal. The same-name terminal of the primary side and the different-name terminal of the secondary side are connected together. The same-name terminal of the secondary side is connected to the mechanical switch. The secondary side of the coupling inductor and the IGBT are connected in parallel and then in series with the mechanical switch to form the main branch. The energy storage capacitor and the commutator inductor are connected in series to form a commutator branch, which is connected in parallel with the main branch. The power dissipation branch is connected in parallel with both the main branch and the commutator branch. By introducing the topology of the primary side of the coupling inductor, the secondary side of the coupling inductor, and the IGBT, the mutual inductance of the coupling inductor is used to convert the energy of the DC system, thereby using the converted energy to charge the energy storage capacitor in the circuit breaker. Compared with the prior art, this application can directly construct an energy storage capacitor charging mechanism without external power supply by means of the mutual inductance between the primary and secondary sides of the coupled inductor when the circuit breaker is placed in the operating environment. At the same time, it can realize fault current limiting and mechanical switch arc extinguishing functions, thereby achieving the technical effect of improving capacitor charging efficiency. Attached Figure Description

[0050] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0051] Figure 1 Schematic diagram of the bypass coupling DC circuit breaker provided in this application Figure 1 ;

[0052] Figure 2 Schematic diagram of the bypass coupling DC circuit breaker provided in this application Figure 2 ;

[0053] Figure 3 Schematic diagram of the bypass coupling DC circuit breaker provided in this application Figure 3 ;

[0054] Figure 4 Schematic diagram of the bypass coupling DC circuit breaker provided in this application Figure 4 ;

[0055] Figure 5 Schematic diagram of the bypass coupling DC circuit breaker provided in this application Figure 5 ;

[0056] Figure 6 Schematic diagram of the bypass coupling DC circuit breaker provided in this application Figure 6 ;

[0057] Figure 7 A flowchart illustrating the control method for the bypass-coupled DC circuit breaker provided in this application. Figure 1 ;

[0058] Figure 8 A flowchart illustrating the control method for the bypass-coupled DC circuit breaker provided in this application. Figure 2 ;

[0059] Figure 9 A schematic diagram of the simulation circuit structure of the bypass-coupled DC circuit breaker provided in this application;

[0060] Figure 10 Simulated waveforms of fault current and voltage interrupted by the bypass-coupled DC circuit breaker provided in this application in a single-ended DC system. Figure 1 ;

[0061] Figure 11 Simulated waveforms of fault current and voltage interrupted by the bypass-coupled DC circuit breaker provided in this application in a single-ended DC system. Figure 2 ;

[0062] Figure 12 Simulated waveforms of fault current and voltage interrupted by the bypass-coupled DC circuit breaker provided in this application in a single-ended DC system. Figure 3 ;

[0063] Figure 13 A schematic diagram of the control device for the bypass coupling DC circuit breaker provided in this application;

[0064] Figure 14 A schematic diagram of the structure of the electronic device provided in this application.

[0065] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0066] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0067] In the existing technology, the working mode of mechanical high-voltage DC circuit breakers is mainly as follows: when the DC system is running normally, the normal current of the DC system flows through the main branch of the circuit breaker; when the DC system fails, the control system of the circuit breaker controls the mechanical switch of the circuit breaker to open, and uses the energy storage capacitor and inductor to form an oscillating circuit to transfer the fault current of the DC system to the energy-consuming branch.

[0068] However, existing mechanical DC circuit breakers rely on external power sources or large capacitor devices to charge energy storage capacitors, and the energy distribution between capacitors is affected by factors such as capacitance differences and coulombic efficiency, resulting in low charging efficiency.

[0069] To address the aforementioned technical problems, this application proposes the following technical concept: by introducing a cooperative control topology between the primary and secondary sides of a coupled inductor and an insulated gate bipolar transistor, a charging mechanism for the energy storage capacitor without an external power source is constructed through the mutual inductance between the primary and secondary sides of the coupled inductor, while simultaneously realizing the arc extinguishing function of a mechanical switch. Specifically, the primary side of the coupling inductor is connected to the DC system, and the secondary side is connected in parallel with an insulated-gate bipolar transistor (IGBT) and then in series with a mechanical switch to form the main branch. The commutation branch formed by the energy storage capacitor and the commutation inductor, as well as the energy dissipation branch, are connected in parallel with the main branch. During normal operation, the current flows through the primary and secondary sides of the coupling inductor and the mechanical switch. When a fault occurs, the IGBT turns on first to shunt the current. During the disconnection process of the mechanical switch, the fault current on the primary side of the coupling inductor changes abruptly and induces an electromotive force on the secondary side through mutual inductance, directly charging the energy storage capacitor. No additional charging device is required, which avoids the system complexity and reliability risks caused by external power supply and solves the problem of uneven energy distribution of the capacitor. At the same time, the commutation branch of the energy storage capacitor and the commutation inductor and the main branch form a high-frequency resonant circuit, generating an oscillating current that is superimposed with the fault current, causing the mechanical switch current to cross zero and achieve arc-free disconnection. Ultimately, this achieves the synergistic effect of self-charging and rapid arc extinguishing, thereby improving the technical effect of capacitor charging efficiency.

[0070] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0071] Figure 1 Schematic diagram of the bypass coupling DC circuit breaker provided in this application Figure 1 ,like Figure 1As shown, the circuit breaker includes: a primary winding of a coupling inductor L1, a secondary winding of a coupling inductor L2, an energy storage capacitor C, a commutation inductor L, an insulated-gate bipolar transistor (IGBT), a mechanical switch MS, and a power dissipation branch B1. The opposite-named terminal of the primary winding of the coupling inductor L1 is connected to the DC system, and the same-named terminal of the primary winding of the coupling inductor L1 is connected to the opposite-named terminal of the secondary winding of the coupling inductor L2. The same-named terminal of the secondary winding of the coupling inductor L2 is connected to the mechanical switch MS. The secondary winding of the coupling inductor L2, connected in parallel with the IGBT, is then connected in series with the mechanical switch MS to form the main branch B2. The energy storage capacitor C, connected in series with the commutation inductor L, forms the commutation branch B3, which is connected in parallel with the main branch B2. The power dissipation branch B1 is connected in parallel with both the main branch B2 and the commutation branch B3.

[0072] In this embodiment, the mutual inductance between the primary side L1 and the secondary side L2 of the coupling inductor is used to adjust the charging path of the energy storage capacitor C when the mechanical switch MS is disconnected; the commutation branch B3 is used to provide oscillating current during the fault current transfer process, causing the current of the mechanical switch MS to cross zero to achieve arc extinction.

[0073] exist Figure 1 Based on the illustrated embodiment, this application also provides a bypass coupled DC circuit breaker with a surge arrester forming an energy-dissipating branch. Figure 2 Schematic diagram of the bypass coupling DC circuit breaker provided in this application Figure 2 ,like Figure 2 As shown, the circuit breaker includes: a primary winding of a coupling inductor L1, a secondary winding of a coupling inductor L2, an energy storage capacitor C, a commutation inductor L, an insulated-gate bipolar transistor (IGBT), a mechanical switch MS, and a surge arrester MOV. The surge arrester MOV is connected in parallel with the main branch and the commutation branch to form an energy dissipation branch.

[0074] In this embodiment, the surge arrester MOV is used to switch to a low-resistance state after the fault current is transferred to the converter branch and the voltage across its terminals reaches the preset operating voltage in order to absorb the remaining fault energy of the system and avoid overvoltage damage to the components.

[0075] Optionally, the primary side L1 and the secondary side L2 of the coupled inductor adopt a multi-winding structure, which includes at least two windings. The turns ratio of each winding is adjusted within a preset range. The windings are arranged in a layered winding or a concentric winding to adapt to the current limiting requirements of different DC systems.

[0076] Optionally, when the circuit breaker is in normal operation, the current of the DC system flows through the primary side L1 of the coupled inductor, the secondary side L2 of the coupled inductor, and the mechanical switch MS. At this time, the primary side L1 and the secondary side L2 of the coupled inductor have no mutual inductance, the insulated gate bipolar transistor IGBT is in the open state, and no current flows through the commutation branch and the energy dissipation branch.

[0077] For example, Figure 3 Schematic diagram of the bypass coupling DC circuit breaker provided in this application Figure 3 ,like Figure 3 As shown, the arrows from left to right indicate that the current in the DC system flows from the opposite-named terminal of the primary side L1 of the coupling inductor to the same-named terminal of the secondary side of the coupling inductor, and then flows from the opposite-named terminal of the secondary side of the coupling inductor to the mechanical switch MS. At this time, there is no mutual inductance between the primary side L1 and the secondary side L2 of the coupling inductor, and the current in the DC system flows out normally through this bypass coupling DC circuit breaker.

[0078] Optionally, when the circuit breaker is in the current transfer phase and the contacts of the mechanical switch MS are separated to the rated opening distance, the insulated gate bipolar transistor IGBT closes; the mechanical switch MS, the insulated gate bipolar transistor IGBT, the energy storage capacitor C, and the commutation inductor L form a closed loop, and the energy storage capacitor C and the commutation inductor L generate a high-frequency oscillating current in the closed loop.

[0079] It should be noted that the current transfer stage refers to the transition process in which the fault current generated by the DC system fault is transferred from the main branch of the circuit breaker to the dedicated arc-extinguishing circuit. In this embodiment, the arc-extinguishing circuit refers to the energy-dissipating branch used for fault current energy dissipation.

[0080] For example, Figure 4 Schematic diagram of the bypass coupling DC circuit breaker provided in this application Figure 4 ,like Figure 4 As shown, a fault occurs in the DC system at time t0. Assume the short-circuit fault occurs on the right side of the circuit breaker, and the fault current increases rapidly after the fault occurs, such as... Figure 4 As shown, the primary side L1 of the coupled inductor generates a voltage, and the secondary side L2 of the coupled inductor induces an oscillating voltage, which also appears across the energy storage capacitor C. At this time, the voltage frequency of the energy storage capacitor C is determined by the coupled inductor.

[0081] At time t1, when the oscillation begins, the circuit breaker's control system issues a tripping command to the mechanical switch MS. The contacts of the mechanical switch MS begin to separate. At time t2, the contacts of the mechanical switch MS separate to their rated opening position, and the insulated gate bipolar transistor (IGBT) closes. At this time, the circuit breaker's on / off state is as follows: Figure 5 As shown. Figure 5 Schematic diagram of the bypass coupling DC circuit breaker provided in this application Figure 5 ,exist Figure 5 In this circuit, the mechanical switch MS, the insulated-gate bipolar transistor IGBT, the energy storage capacitor C, and the commutation inductor L form a closed loop. The energy storage capacitor C and the commutation inductor L generate a high-frequency oscillating current with an oscillation frequency of [frequency missing]. Assume that the voltage across the energy storage capacitor is U when the insulated gate bipolar transistor (IGBT) is closed. C Then the peak value of the high-frequency oscillating current is The closing of an insulated-gate bipolar transistor (IGBT) needs to be set as close as possible to the energy storage capacitor voltage U. C At the amplitude of , the peak value of the oscillation current can be maximized.

[0082] At time t3, the insulated-gate bipolar transistor (IGBT) is turned off, and current begins to transfer from the IGBT to the secondary side of the coupling inductor L2, similar to the state at time t0. The oscillating voltage across the energy storage capacitor C is determined by the secondary side of the coupling inductor L2. At time t4, the IGBT is turned on, and the high-frequency oscillating current generated by the energy storage capacitor C and the commutation inductor L is superimposed on the mechanical switch MS.

[0083] At time t5, the current in the mechanical switch MS crosses zero, extinguishing the arc and turning off. Figure 6 As shown, the DC system charges the energy storage capacitor C, and the voltage across the energy storage capacitor C rises rapidly.

[0084] It should be noted that during a DC system fault, the commutation branch formed by the energy storage capacitor C and the commutation inductor L constitutes a closed loop with the main branch. Utilizing the electromagnetic coupling characteristics of the energy storage capacitor and the commutation inductor, a sinusoidal alternating current with a frequency much higher than the fault current is generated, i.e., a high-frequency oscillating current. By superimposing the high-frequency oscillating current with the DC system fault current, a current zero-crossing point is created, thereby providing conditions for the circuit breaker to extinguish the arc.

[0085] Optionally, when the circuit breaker is in the energy absorption stage and the voltage across the surge arrester MOV reaches its preset operating voltage, the surge arrester MOV switches to the working state.

[0086] In this embodiment, when the surge arrester MOV is in operation, the surge arrester MOV converts fault energy into heat energy dissipation through nonlinear resistance characteristics, while limiting the voltage across the mechanical switch MS to below a first preset threshold, thus preventing insulation breakdown of the mechanical switch MS.

[0087] For example, at time t6, the voltage across the surge arrester MOV reaches the operating voltage of the surge arrester MOV, the surge arrester MOV operates, and energy is dissipated in the energy-consuming branch. At time t7, the surge arrester MOV completes energy absorption and exits operation.

[0088] It should be noted that, in Figures 2 to 6 In the embodiment shown, t0 <t1<t2<t3<t4<t5<t6<t7。

[0089] The bypass coupling DC circuit breaker method provided in this application includes a primary side of a coupling inductor, a secondary side of a coupling inductor, an energy storage capacitor, a commutation inductor, an insulated-gate bipolar transistor (IGBT), a mechanical switch, and an energy dissipation branch. The primary side of the coupling inductor is connected to the DC system via a different-named terminal. The same-named terminal of the primary side and the different-named terminal of the secondary side are connected together. The same-named terminal of the secondary side is connected to the mechanical switch. The secondary side of the coupling inductor and the IGBT are connected in parallel and then in series with the mechanical switch to form the main branch. The energy storage capacitor and the commutation inductor are connected in series to form a commutation branch, which is connected in parallel with the main branch. The energy dissipation branch is connected in parallel with both the main branch and the commutation branch. By introducing the topology of the primary side of the coupling inductor, the secondary side of the coupling inductor, and the IGBT, the mutual inductance of the coupling inductor is used to convert the energy in the DC system, thereby using the converted energy to charge the energy storage capacitor in the circuit breaker. Compared with the prior art, this application allows the energy storage capacitor inside the circuit breaker to be charged directly based on the DC system connected to the circuit breaker when the circuit breaker is placed in the operating environment, thus avoiding dependence on external power supply and achieving the technical effect of improving capacitor charging efficiency.

[0090] Figure 7 A flowchart illustrating the control method for the bypass-coupled DC circuit breaker provided in this application. Figure 1 ,like Figure 7 As shown, this method is applied to the above Figures 1 to 6 The bypass-coupled DC circuit breaker corresponding to any possible implementation method includes:

[0091] S701: Real-time acquisition of the voltage value of the energy storage capacitor in the bypass coupled DC circuit breaker, as well as the main branch current of the bypass coupled DC circuit breaker.

[0092] In this step, the main branch current includes the normal current during the normal operation phase and the fault current during the current transfer phase. The energy storage capacitor voltage is acquired using a voltage sensor, such as a Hall voltage sensor or a voltage divider sampling module. The main branch current is acquired using a current sensor, such as a Rogowski coil or a Hall current sensor.

[0093] For example, the capacitance and current can be acquired as follows: during normal operation, data is continuously acquired at a frequency of 10~100Hz. In a fault state, after fault detection is triggered, the acquisition frequency is increased to 10~100kHz to capture rapid changes in fault current. The acquired voltage or current signal is converted into a digital signal by an analog-to-digital converter and transmitted to the controller for real-time processing.

[0094] Optionally, when collecting the fault current, the rise parameter of the fault current can also be collected, and the mutual inductance coefficient of the coupling inductor in the bypass coupling DC circuit breaker can be adjusted based on the rise parameter of the fault current, specifically:

[0095] S7011: Collect the rise rate parameter corresponding to the current fault current in the main branch.

[0096] In this step, the fault current rise rate refers to the rate of change of the fault current over time. It is a core indicator for judging the severity of the fault. The higher the rise rate, the more severe the fault, and the faster the peak fault current increases, requiring rapid current limiting. The rise rate parameter can be collected in real time using the following methods:

[0097] After the DC system enters a fault state, the instantaneous value of the main branch current is collected at preset time intervals; the current change is calculated based on the instantaneous current values ​​of two adjacent time intervals; and the ratio of the current change to the time interval is used as the rise rate parameter of the fault current.

[0098] For example, under fault conditions, instantaneous values ​​of the main branch current are acquired at fixed time intervals of 5 to 10 μs. The difference between two adjacent instantaneous values ​​is calculated, and the rise rate parameter is calculated based on this difference.

[0099] S7012. When the rise rate parameter is higher than the historical change rate, increase the mutual inductance coefficient between the primary and secondary sides of the coupling inductor in the bypass coupled DC circuit breaker, and update the historical change rate based on the rise rate parameter.

[0100] In this step, the historical rate of change refers to the current change rate corresponding to the previously stored fault current. Different rates of change can represent fault currents caused by different fault types. For example, the current amplitude of a short-circuit ground fault exceeds the rated current of a DC system by several times, therefore its corresponding rate of change is large. The fault current of a high-resistance ground fault is significantly lower than the rated current, resulting in a low calculated rate of change. The coupling inductor consists of a primary winding and a secondary winding, achieving energy transfer and current control through electromagnetic coupling. The mutual inductance coefficient reflects the coupling strength between the primary and secondary windings; the larger the mutual inductance coefficient, the larger the equivalent inductance value of the coupling inductor, and the stronger its ability to impede current changes.

[0101] For example, the mutual inductance coefficient can be adjusted by reserving an adjustable air gap in the coupled inductor core, and reducing the air gap width through an electromagnetic drive mechanism. The smaller the air gap, the stronger the magnetic coupling and the larger the mutual inductance coefficient.

[0102] S7013. When the rise rate parameter is lower than the historical change rate, reduce the mutual inductance coefficient between the primary and secondary sides of the coupled inductor, and update the historical change rate based on the rise rate parameter.

[0103] In this step, the rate of increase is lower than the historical rate of change, indicating that the fault current is increasing slowly and strong current limiting is not required. If the mutual inductance coefficient is too large, it will lead to an excessively large equivalent inductance in the oscillation circuit. An excessively large inductance will reduce the high-frequency oscillation frequency, and the interval at the zero crossing point will become longer, affecting the arc extinguishing efficiency. Therefore, the mutual inductance coefficient needs to be reduced to ensure the oscillation frequency.

[0104] S702, Adjusting the closing timing of insulated gate bipolar transistors in bypass coupled DC circuit breakers based on voltage values.

[0105] In this step, the insulated-gate bipolar transistor (IGBT) refers to the core switching device in a DC circuit breaker that controls the on / off state of the oscillation circuit. Its closing sequence directly determines the start-up timing of the oscillation circuit. The purpose of adjusting the closing sequence is to ensure precise coordination between the start-up of the oscillation circuit and the disconnection of the mechanical switch. This ensures that the energy storage capacitor has sufficient energy to generate the peak oscillation current while preventing the IGBT from closing and causing a short circuit in the corresponding main branch circuit if the mechanical switch is not disconnected.

[0106] Alternatively, one possible implementation of adjusting the closing timing is as follows:

[0107] S7021. Continuously determine whether the voltage value of the energy storage capacitor obtained in real time reaches the second preset threshold.

[0108] In this step, the second preset threshold refers to the critical value of the capacitor voltage set according to the peak current requirement of the oscillation circuit composed of the energy storage capacitor and the commutation inductor. When the energy storage capacitor voltage reaches this value, the discharge energy is sufficient, and the peak value of the oscillation current can cover the amplitude of the fault current, thus effectively superimposing a zero value. The purpose of continuous judgment is to prevent the insulated gate bipolar transistor from closing when the capacitor voltage is insufficient or when the voltage is too high.

[0109] S7022. Simultaneously determine whether the contacts of the mechanical switch in the bypass coupling DC circuit breaker have separated to the rated opening distance.

[0110] In this step, the method to determine whether the contacts of the mechanical switch have separated to the rated opening distance can be: monitoring the rate of change of the main branch current; if the rate of change of the main branch current is less than or equal to the preset stable threshold, and the fluctuation of the current amplitude within the preset time window does not exceed the preset proportion of the normal current rated value, then it is determined that the contacts of the mechanical switch have separated to the rated opening distance.

[0111] S7023. When the mechanical switch contacts separate to the rated opening distance and the energy storage capacitor voltage reaches the second preset threshold, a closing command is sent to the insulated gate bipolar transistor to control its closing.

[0112] In this step, the second preset threshold is the voltage threshold that ensures the energy storage capacitor and commutation inductor generate the maximum peak high-frequency oscillation current. Only when both conditions are met simultaneously can the insulated-gate bipolar transistor be closed. The purpose is to ensure that the oscillation circuit has sufficient energy while also ensuring that there is no short circuit between the main circuit and the oscillation circuit.

[0113] S703, Adjusting the energy distribution ratio in the bypass coupled DC circuit breaker based on the main branch current.

[0114] In this step, the energy distribution ratio refers to the input ratio of the energy storage capacitor in the bypass coupled DC circuit breaker.

[0115] Alternatively, one possible way to adjust the energy distribution ratio is as follows:

[0116] S7031: After the insulated gate bipolar transistor is closed, the zero-crossing state of the main branch current is monitored in real time.

[0117] In this step, the zero-crossing state refers to the moment when the total current of the main branch, i.e., the fault DC current plus the high-frequency oscillation current, is zero. This is the optimal window for the circuit breaker to extinguish the arc. The purpose of monitoring the zero-crossing point is that when the zero-crossing point appears, it indicates that the oscillation circuit has been working normally, and energy distribution adjustment needs to be initiated to avoid excessive energy input.

[0118] S7032. When a zero-crossing point is detected in the main branch current, adjust the energy distribution ratio to reduce the energy input from the coupling inductor to the energy storage capacitor in the bypass coupled DC circuit breaker.

[0119] In this step, the logic for adjusting the energy distribution ratio is as follows: when a zero-crossing occurs, it indicates that the oscillation circuit has created an arc-extinguishing window. At this point, it is unnecessary to continue inputting a large amount of energy into the capacitor. Reducing the input ratio allows the oscillation energy to gradually decay, avoiding secondary arcing. The purpose of adjusting the energy distribution ratio is to balance the oscillation energy required for arc extinguishing with the energy decay required for circuit stability, ensuring that after the fault current is cut off at the zero-crossing point, there is no residual energy in the circuit that could cause the arc to reignite.

[0120] Based on the above embodiments, this application also provides a method for adjusting the parameters of the energy storage capacitor and the commutator inductor in a bypass-coupled DC circuit breaker. Figure 8 A flowchart illustrating the control method for the bypass-coupled DC circuit breaker provided in this application. Figure 2 ,like Figure 8 As shown, the method includes:

[0121] A1. Real-time acquisition of DC system operating status parameters, including at least system load rate, fault current level, and DC system voltage fluctuation amplitude.

[0122] A2. When the system load rate is less than or equal to the preset load threshold, reduce the capacitance of the energy storage capacitor and simultaneously reduce the inductance of the commutation inductor.

[0123] A3. When the fault current level is greater than or equal to the preset fault current threshold, increase the capacitance of the energy storage capacitor and simultaneously increase the inductance of the commutation inductor.

[0124] In this step, the preset fault current threshold is a preset multiple of the rated current of the DC system.

[0125] A4. When the voltage fluctuation amplitude of the DC system is greater than or equal to the preset voltage fluctuation threshold, adjust the ratio of the energy storage capacitor value to the converter inductor value so that the oscillation frequency of the converter branch and the system voltage fluctuation frequency have a preset antagonistic relationship.

[0126] It should be noted that when adjusting the capacitance value of the energy storage capacitor and the inductance value of the commutator, it is necessary to ensure that the product of the capacitance value of the energy storage capacitor and the inductance value of the commutator is stable within the preset range in order to maintain the basic stability of the oscillation frequency of the commutator branch.

[0127] Figure 9 This is a schematic diagram of the simulation circuit structure of the bypass-coupled DC circuit breaker provided in this application. Figure 10 , Figure 11 as well as Figure 12 The simulation waveforms of the fault current and voltage interruption of the bypass-coupled DC circuit breaker provided in this application in a single-ended DC system are shown. Figure 9 As shown, the circuit includes: a DC power supply U dc Smoothing reactor L dc Short-circuit ground fault f, DC system load R dc The coupling inductor has a primary side L1, a secondary side L2, a mechanical switch MS, an insulated gate bipolar transistor (IGBT), a storage capacitor C, a commutation inductor L, and a surge arrester MOV.

[0128] During the simulation, a DC power supply U is used. dc Instead of a DC system, the power supply voltage is set to 500kV, and the smoothing reactor L... dc The current is 100mH, the system load is 166Ω, the primary side L1 and the secondary side L2 of the circuit breaker are both 2mH, the mutual inductance is 1.9mH, the energy storage capacitor C is 5uf, and the commutation inductance L is 0.32mH.

[0129] like Figures 10 to 12As shown, IGBT is an insulated-gate bipolar transistor, MS is a mechanical switch, C is a capacitor, L is an inductor, and MOV is a surge arrester; Udc is the DC system voltage, Ldc is the smoothing reactor, Rdc is the DC system load, and f is the short-circuit ground fault; Icb is the current of the mechanical switch MS, IC is the current of the energy storage capacitor C, Imov is the current of the surge arrester MOV, Is is the short-circuit fault current, Ucb is the voltage of the mechanical switch MS, Uc is the capacitor voltage, UL1 is the voltage of the primary side L1 of the coupled inductor, and UL2 is the voltage of the secondary side L2 of the coupled inductor. The fault is set to occur in 0.4s. The fault current rises rapidly from 3kA, and the voltage of the energy storage capacitor C begins to oscillate. After 4ms, the mechanical switch MS opens, the IGBT closes, and the commutator branch generates an oscillating current. At this time, the amplitude of the oscillating current is small and cannot generate a zero-crossing point in the mechanical switch MS branch. At 0.4041s, the insulated-gate bipolar transistor IGBT opens, and the voltage of the energy storage capacitor C rises again. At 0.4045s, the insulated-gate bipolar transistor IGBT closes again. At this time, the IGBT closes at a voltage amplitude close to 150kV near the energy storage capacitor C. The high-frequency oscillating current generated by the energy storage capacitor C and the commutator inductor L is superimposed on the mechanical switch MS, resulting in a current zero-crossing point, interrupting the 20kA fault current. The peak current of the mechanical switch MS is around 40kA. The MS arc is extinguished and turned off. Subsequently, the energy storage capacitor C is charged by the DC system, and the surge arrester MOV operates, limiting the voltage of the mechanical switch MS to below 800kV.

[0130] Figure 13 A schematic diagram of the control device for the bypass-coupled DC circuit breaker provided in this application is shown below. Figure 13 As shown, the control device for the bypass-coupled DC circuit breaker provided in this embodiment includes:

[0131] The acquisition module 1301 is used to acquire in real time the voltage value of the energy storage capacitor in the bypass coupled DC circuit breaker, as well as the main branch current of the bypass coupled DC circuit breaker; wherein, the main branch current includes the normal current during the normal operation phase and the fault current during the current transfer phase.

[0132] The first processing module 1302 is used to adjust the closing timing of the insulated gate bipolar transistor in the bypass coupled DC circuit breaker based on the voltage value;

[0133] The second processing module 1303 is used to adjust the energy distribution ratio in the bypass coupled DC circuit breaker based on the main branch current; wherein, the energy distribution ratio refers to the input ratio of the energy storage capacitor in the bypass coupled DC circuit breaker.

[0134] Optionally, in one possible implementation, the first processing module 1302 is further configured to:

[0135] Continuously determine whether the voltage value of the energy storage capacitor obtained in real time reaches the second preset threshold;

[0136] At the same time, determine whether the contacts of the mechanical switch in the bypass coupling DC circuit breaker have separated to the rated opening distance;

[0137] When the mechanical switch contacts separate to the rated opening distance and the energy storage capacitor voltage reaches the second preset threshold, a closing command is sent to the insulated gate bipolar transistor to control its closing.

[0138] The second preset threshold is the voltage threshold that ensures the energy storage capacitor and the commutation inductor generate the maximum peak high-frequency oscillation current.

[0139] Optionally, in one possible implementation, the second processing module 1303 is further configured to:

[0140] After the insulated gate bipolar transistor is closed, the zero-crossing state of the main branch current is monitored in real time.

[0141] When a zero-crossing point is detected in the main branch current, the energy distribution ratio is adjusted to reduce the energy input from the coupling inductor to the energy storage capacitor in the bypass coupled DC circuit breaker.

[0142] The apparatus provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0143] Figure 14 A schematic diagram of the structure of the electronic device provided in this application. Figure 14 As shown, the electronic device provided in this embodiment includes at least one processor 1401 and a memory 1402. Optionally, the device further includes a communication component 1403. The processor 1401, memory 1402, and communication component 1403 are connected via a bus 1404.

[0144] In a specific implementation, at least one processor 1401 executes computer execution instructions stored in memory 1402, causing at least one processor 1401 to execute the above-described bypass coupling DC circuit breaker method or approach.

[0145] The specific implementation process of processor 1401 can be found in the above method embodiment, and its implementation principle and technical effect are similar, so it will not be repeated here.

[0146] In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.

[0147] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage device.

[0148] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0149] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0150] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.

[0151] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0152] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.

[0153] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0154] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0155] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0156] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0157] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0158] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A bypass-coupled DC circuit breaker, characterized in that, include: The primary side of the coupled inductor, the secondary side of the coupled inductor, the energy storage capacitor, the commutation inductor, the insulated gate bipolar transistor, the mechanical switch, and the energy dissipation branch; The opposite-named terminal of the primary side of the coupled inductor is connected to the DC system, the same-named terminal of the primary side of the coupled inductor is connected to the opposite-named terminal of the secondary side of the coupled inductor, and the same-named terminal of the secondary side of the coupled inductor is connected to the mechanical switch. The secondary side of the coupled inductor is connected in parallel with the insulated gate bipolar transistor and then connected in series with the mechanical switch to form the main branch; The energy storage capacitor and the commutation inductor are connected in series to form a commutation branch, and the commutation branch is connected in parallel with the main branch; The energy-consuming branch is connected in parallel with the main branch and the converter branch; The mutual inductance between the primary and secondary sides of the coupled inductor is used to adjust the charging path of the energy storage capacitor when the mechanical switch is disconnected. The commutation branch is used to provide oscillating current during the fault current transfer process, causing the mechanical switch current to cross zero to achieve arc extinction.

2. The circuit breaker according to claim 1, characterized in that, The energy-consuming branch includes a surge arrester; The surge arrester is connected in parallel with the main branch and the converter branch to form the energy-dissipating branch; The surge arrester is used to switch to a low-resistance state to absorb the remaining fault energy of the system and avoid overvoltage damage to components after the fault current is transferred to the converter branch and the voltage across its terminals reaches a preset operating voltage.

3. The circuit breaker according to claim 1, characterized in that, The primary and secondary sides of the coupled inductor adopt a multi-winding structure, which includes at least two windings. The turns ratio of each winding is adjusted within a preset range. The windings are arranged in a layered or concentric manner to adapt to the current limiting requirements of different DC systems.

4. The circuit breaker according to claim 1, characterized in that, When the circuit breaker is in normal operation, the current of the DC system flows through the primary side of the coupling inductor, the secondary side of the coupling inductor, and the mechanical switch. At this time, there is no mutual inductance between the primary side and the secondary side of the coupling inductor, the insulated gate bipolar transistor is in the off state, and no current flows through the commutation branch and the energy dissipation branch.

5. The circuit breaker according to claim 1, characterized in that, When the circuit breaker is in the current transfer phase and the contacts of the mechanical switch are separated to the rated opening distance, the insulated gate bipolar transistor closes; the mechanical switch, the insulated gate bipolar transistor, the energy storage capacitor, and the commutation inductor form a closed loop, and the energy storage capacitor and the commutation inductor generate a high-frequency oscillating current in the closed loop.

6. The circuit breaker according to claim 2, characterized in that, When the circuit breaker is in the energy absorption stage and the voltage across the surge arrester reaches its preset operating voltage, the surge arrester switches to the working state. When the surge arrester is in operation, it converts fault energy into heat energy dissipation through nonlinear resistance characteristics, while limiting the voltage across the mechanical switch to below a first preset threshold to prevent insulation breakdown of the mechanical switch.

7. A control method for a bypass-coupled DC circuit breaker, applied to the bypass-coupled DC circuit breaker according to any one of claims 1-6, characterized in that, include: The voltage value of the energy storage capacitor in the bypass coupled DC circuit breaker and the main branch current of the bypass coupled DC circuit breaker are collected in real time; wherein, the main branch current includes the normal current during normal operation and the fault current during current transfer. The closing timing of the insulated gate bipolar transistor in the bypass coupling DC circuit breaker is adjusted based on the voltage value; The energy distribution ratio in the bypass coupled DC circuit breaker is adjusted based on the main branch current; wherein, the energy distribution ratio refers to the input ratio of the energy storage capacitor in the bypass coupled DC circuit breaker.

8. The method according to claim 7, characterized in that, The adjustment of the closing timing of the insulated-gate bipolar transistor in the bypass-coupled DC circuit breaker based on the voltage value includes: Continuously determine whether the voltage value of the energy storage capacitor obtained in real time reaches the second preset threshold; At the same time, it is determined whether the contacts of the mechanical switch in the bypass coupling DC circuit breaker have separated to the rated opening distance; When the mechanical switch contacts separate to the rated opening distance and the energy storage capacitor voltage reaches the second preset threshold, a closing command is sent to the insulated gate bipolar transistor to control its closing. The second preset threshold is a voltage threshold that ensures the energy storage capacitor and the commutation inductor generate the maximum peak high-frequency oscillation current.

9. The method according to claim 7, characterized in that, The adjustment of the energy distribution ratio in the bypass coupled DC circuit breaker based on the main branch current includes: After the insulated gate bipolar transistor is closed, the zero-crossing state of the main branch current is monitored in real time. When the main branch current is detected to have crossed zero, the energy distribution ratio is adjusted to reduce the energy input from the coupling inductor in the bypass coupling DC circuit breaker to the energy storage capacitor.

10. A control device for a bypass-coupled DC circuit breaker, applied to the bypass-coupled DC circuit breaker according to any one of claims 1-6, characterized in that, include: The acquisition module is used to collect the voltage value of the energy storage capacitor in the bypass coupled DC circuit breaker and the main branch current of the bypass coupled DC circuit breaker in real time; wherein, the main branch current includes the normal current during the normal operation phase and the fault current during the current transfer phase. The first processing module is used to adjust the closing timing of the insulated gate bipolar transistor in the bypass coupling DC circuit breaker based on the voltage value. The second processing module is used to adjust the energy distribution ratio in the bypass coupled DC circuit breaker based on the main branch current; wherein the energy distribution ratio refers to the input ratio of the energy storage capacitor in the bypass coupled DC circuit breaker.

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