High-voltage direct-current circuit breaker topology with voltage regulating function and control method of high-voltage direct-current circuit breaker topology

Abstract

The invention belongs to the field of high-voltage direct-current circuit breakers, and particularly discloses a high-voltage direct-current circuit breaker topology with a voltage regulation function and a control method thereof, and the high-voltage direct-current circuit breaker topology comprises a through-flow branch, a current conversion unit, a current interception unit, a voltage regulation branch and an energy absorption branch. The voltage regulating branch is connected in parallel with two sides of the capacitor in the current conversion unit; the voltage regulating branch comprises a voltage-stabilizing lightning arrester and a high-energy resistor which are connected in series, and is used for absorbing residual energy after the capacitor establishes a transient voltage, slowing down the voltage rising rate of the capacitor in the current conversion unit and regulating the internal voltage of the capacitor to a voltage level required by switching on and switching off; the energy absorption branch is used for absorbing residual energy in the direct-current power transmission line and limiting overvoltage generated by breaking of the through-current branch; and the cut-off unit is used for cutting off a path between the cut-off unit and the current conversion unit after the action of the energy absorption branch is detected, and cutting off the current generated in the action process of the voltage regulation branch. Capacitance voltage regulation is realized, so that the circuit breaker has a reclosing switching-on and switching-off function.

Description

Technical Field

[0001] This application belongs to the field of high-voltage direct current circuit breakers, and more specifically, relates to a topology of a high-voltage direct current circuit breaker with a voltage regulation function and its control method. Background Art

[0002] Due to the low damping characteristics of the flexible direct current system, its requirements for the quick operation and selectivity of protection equipment are higher than those of the alternating current system. To ensure the safe and reliable operation of the direct current power grid, a high-voltage direct current circuit breaker (HVDCCB) is usually selected as an effective means for fault isolation and clearance. Currently, direct current circuit breakers are divided into three types: hybrid, mechanical, and solid-state. Among them, mechanical and hybrid direct current circuit breakers are often applied to high-voltage direct current transmission systems, and their application and technological development have further improved the reliability and stability of the flexible direct current system.

[0003] To ensure that the flexible direct current transmission network has a certain self-regulating ability and stability, the power system usually requires that protection devices such as switches can complete reclosing within a specified time after disconnection to prevent unnecessary losses caused by the long-term shutdown of the transmission line due to temporary transient faults. After a high-voltage mechanical circuit breaker completes a single breaking, the capacitor in the commutation circuit is often in a high-voltage state, which is extremely unfavorable for the reclosing operation of the circuit breaker. Therefore, it usually requires a charging device to quickly adjust the capacitor to reduce it to a voltage level that meets the requirements for secondary breaking, and the charging device with this function generally has a high cost, which also increases the overall cost of the circuit breaker. Summary of the Invention

[0004] Aiming at the defects of the prior art, the purpose of this application is to provide a topology of a high-voltage direct current circuit breaker with a voltage regulation function and its control method, aiming to solve the problem that the capacitor voltage is too high after a single opening of a high-voltage mechanical direct current circuit breaker, resulting in the inability to achieve reclosing breaking.

[0005] To achieve the above purpose, in the first aspect, this application provides a topology of a high-voltage direct current circuit breaker with a voltage regulation function, including: a current-carrying branch, a commutation unit, a current-interrupting unit, a voltage regulation branch, and an energy absorption branch; both ends of the current-carrying branch are respectively connected to the direct current transmission line; one end of the commutation unit is connected to one end of the current-interrupting unit, and the other end is connected to one end of the energy absorption branch; the other end of the current-interrupting unit is connected to the other end of the energy absorption branch; the voltage regulation branch is connected in parallel on both sides of the capacitor in the commutation unit; The current-carrying branch is used to conduct the rated current and disconnect when a fault occurs in the DC transmission line; the current-interrupting unit is used to connect the converter unit to the DC transmission line after the current-carrying branch is disconnected; the converter unit is used to generate a high-frequency oscillating current to achieve current transfer under fault conditions; the voltage-regulating branch includes a voltage-stabilizing lightning arrester and a high-energy resistor connected in series, which is used to absorb the residual energy after the capacitor in the converter unit builds up a transient voltage, so as to slow down the rising rate of the capacitor voltage in the converter unit and adjust the internal voltage of the capacitor to the voltage level required for opening; the energy absorption branch is used to absorb the residual energy of the DC transmission line and limit the overvoltage generated by the fast mechanical switch of the current-carrying branch; the current-interrupting unit is used to disconnect the path between it and the converter unit after detecting the action of the energy absorption branch, and cut off the current generated during the action of the voltage-regulating branch.

[0006] Further preferably, the current-interrupting unit includes an inner layer composed of a plurality of integrated gate-commutated thyristors (IGCTs) connected in series with a plurality of thyristors (SCRs), and an outer layer composed of a bridge structure formed by a first diode, a second diode, a third diode, and a fourth diode according to the current flow direction. Further preferably, the energy absorption branch is a plurality of lightning arresters.

[0007] Further preferably, when the DC transmission line is put into operation for the first time, the capacitor of the converter unit is energized by an external charging device.

[0008] Further preferably, the IGCTs inside the current-interrupting unit need to meet the current-carrying requirements, and the first diode, the second diode, the third diode, the fourth diode, and the SCR need to meet the current-carrying requirements and the withstand voltage requirements.

[0009] Further preferably, the pre-charging voltage of the capacitor in the converter unit satisfies at least providing 4 current zero-crossing points, and the pre-charging voltage of the capacitor and the threshold voltage of the voltage-stabilizing lightning arrester in the voltage-regulating branch satisfy:

[0010] Among them, the damping angular frequency , r is the impedance of the DC transmission line; is the expected fault current value to be interrupted; L is the inductance of the converter unit; t is the operation time of the converter unit; U is the pre-charging voltage of the capacitor in the converter unit, which is also the threshold voltage of the voltage-stabilizing lightning arrester; C is the capacitance value of the converter unit.

[0011] Further preferably, the current that the IGCTs inside the current-interrupting unit need to cut off is:

[0012] Among them, represents the action voltage of the energy absorption branch; is the threshold voltage of the voltage-stabilizing arrester; is the steady-state impedance of the voltage-stabilizing arrester; R is the high-energy resistor.

[0013] In a second aspect, the present application provides a control method for a high-voltage DC circuit breaker topology with a voltage regulation function, including the following steps: Step S1: At time t0, when a fault occurs in the DC transmission line, the fault current rapidly rises until the fault current is detected at time t1, and a tripping command is sent to the fast mechanical switch in the current-carrying branch; Step S2: At time t2, after the fast mechanical switch trips to an effective opening distance, a conduction signal is first sent to the IGCT in the current-intercepting unit, and then a conduction signal is sent to the SCR to activate the commutation unit; Step S3: At time t3, all the fault current in the current-carrying branch is completely transferred, and the fault current continuously charges the capacitor in the commutation unit through the current-intercepting unit, causing the voltage across the capacitor to continuously rise; Step S4: At time t4, when the voltage-regulating branch reaches the threshold voltage and operates, a part of the fault current is transferred to the voltage-regulating branch to slow down the rising rate of the capacitor voltage until the energy absorption branch reaches the operating voltage at time t5, and most of the fault current is transferred; Step S5: At time t6, when it is detected that the energy absorption branch operates, a turn-off signal is sent to the current-intercepting unit to first turn off the IGCT in the current-intercepting unit, and finally the SCR turns off by itself, and all the fault current is transferred to the energy absorption branch until the energy consumption is completed at time t7; Step S6: After the fault current is cut off, the voltage-regulating branch continues to operate to adjust the capacitor to the threshold voltage to prepare for reclosing interruption.

[0014] Generally speaking, compared with the prior art through the above technical solutions conceived by the present application, the following beneficial effects are achieved: The present application provides a high-voltage DC circuit breaker topology with a voltage regulation function. The voltage-stabilizing arrester SMOV and the high-energy resistor R are connected in series to form a voltage-regulating branch with an autonomous voltage regulation function, and are connected in parallel on both sides of the capacitor C of the commutation unit. By using the special function of this branch, the voltage of the capacitor C is reduced to below the 1 mA - 10 mA reference voltage of the voltage-stabilizing arrester SMOV in a short time, and part of the system energy caused by the fault during the opening process is absorbed. At the same time, the current-intercepting unit is used to cut off the small current generated due to the operation of the voltage-regulating branch, reducing the number of fully controlled devices used; the settings of the commutation unit, the voltage-regulating branch and the current-intercepting unit can be applied to any resonant high-voltage DC circuit breaker that uses a capacitor to establish a transient voltage as the commutation circuit, realizing capacitor voltage regulation to enable the circuit breaker to have a reclosing interruption function, and having good economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is the circuit topology diagram of the high-voltage DC circuit breaker with voltage regulation function provided by the embodiment of the present application; Figure 2 is the control timing diagram of the topology of the high-voltage DC circuit breaker with voltage regulation function provided by the embodiment of the present application; Figure 3 is the schematic diagram of the opening principle of the topology of the high-voltage DC circuit breaker with voltage regulation function provided by the embodiment of the present application; Figure 4(a) is the schematic diagram of the current loop of the topology of the high-voltage DC circuit breaker with voltage regulation function in the time sequence of t0~t1 provided by the embodiment of the present application; Figure 4(b) is the schematic diagram of the current loop of the topology of the high-voltage DC circuit breaker with voltage regulation function in the time sequence of t1~t2 provided by the embodiment of the present application; Figure 4(c) is the schematic diagram of the current loop of the topology of the high-voltage DC circuit breaker with voltage regulation function in the time sequence of t3~t4 provided by the embodiment of the present application; Figure 4(d) is the schematic diagram of the current loop of the topology of the high-voltage DC circuit breaker with voltage regulation function in the time sequence of t4~t5 provided by the embodiment of the present application; Figure 4(e) is the schematic diagram of the current loop of the topology of the high-voltage DC circuit breaker with voltage regulation function in the time sequence of t5~t6 provided by the embodiment of the present application; Figure 4(f) is the schematic diagram of the current loop of the topology of the high-voltage DC circuit breaker with voltage regulation function in the time sequence of t6~t7 provided by the embodiment of the present application; Figure 5(a) is the current waveform diagram corresponding to the reclosing switch of the topology of the high-voltage DC circuit breaker with voltage regulation function provided by the embodiment of the present application; Figure 5(b) is the voltage waveform diagram corresponding to the reclosing switch of the topology of the high-voltage DC circuit breaker with voltage regulation function provided by the embodiment of the present application. Detailed implementation manners

[0016] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0017] The term "and / or" in this document is a relationship describing associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. The symbol " / " in this document represents an "or" relationship between associated objects. For example, A / B represents A or B.

[0018] The terms "first" and "second" etc. in the specification and claims of this document are used to distinguish different objects, rather than to describe a specific order of the objects.

[0019] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be construed as being more preferred or having more advantages than other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner.

[0020] In the description of the embodiments of the present application, unless otherwise specified, the meaning of "a plurality of" refers to two or more.

[0021] The embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application.

[0022] To solve the problem that the capacitor voltage is too high after the first opening of a high-voltage mechanical DC circuit breaker and reclosing breaking cannot be achieved, the present application proposes a topology of a high-voltage DC circuit breaker with a voltage regulation function and its control method. A voltage regulation module with an independent voltage regulation function is formed by connecting a voltage stabilizing arrestor SMOV and a high-energy resistor R in series, and is connected in parallel on both sides of the capacitor C. By utilizing the special function of this module, the voltage of the capacitor C is reduced to below the 1 mA - 10 mA reference voltage of the voltage stabilizing arrestor SMOV within a short time, and part of the system energy caused by the fault during the opening process is absorbed. At the same time, a current interruption unit is used to interrupt the small current generated due to the operation of the voltage regulation branch; this design can be applied to any resonant high-voltage DC circuit breaker that uses a capacitor to establish a transient voltage as a commutation loop, realizing capacitor voltage regulation and further enabling the circuit breaker to have the function of reclosing breaking; Such as Figure 1As shown in the first aspect, the present application provides a high-voltage DC circuit breaker topology with a voltage regulation function, including: a current-carrying branch, a commutation unit, a current interruption unit, a voltage regulation branch, and an energy absorption branch; wherein, the current-carrying branch is composed of a fast mechanical switch MB in series, and both ends are respectively connected to the DC transmission line, and are used to conduct the rated current and the fault current, and quickly break when a fault occurs, and has low conduction loss and cost; wherein, the commutation unit includes a capacitor C and an oscillating inductor L in series, one end is connected to the current-carrying branch, and one end is connected to the current interruption unit, and is used to generate a high-frequency oscillating current to realize the transfer of current under fault conditions; wherein, the current interruption unit includes an inner layer composed of a plurality of integrated gate-commutated thyristors IGCTs in series with a plurality of thyristors SCRs, and an outer layer composed of a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4 forming a bridge structure according to the current flow direction, one end is connected to the commutation unit, and one end is connected to the energy absorption branch, so that the overall circuit breaker has a bidirectional turn-off function and can cut off the small current generated during the operation of the voltage regulation branch; wherein, the voltage regulation branch includes a voltage stabilizing arrester SMOV and a high-energy resistor R connected in series, and is connected in parallel on both sides of the capacitor C in the commutation unit, and is used to absorb the residual energy after the capacitor establishes a transient voltage and has a voltage regulation function; wherein the energy absorption branch includes a large number of arresters, which are used to absorb the remaining energy of the system and limit the overvoltage generated by the fast mechanical switch of the current-carrying branch; It should be noted that when the capacitor C is first put into operation in the system, it is pre-charged by an external charging device in advance, and the charging voltage polarity does not need to be considered; at the same time, all electronic switches inside the circuit breaker are in the off state, and the circuit breaker presents a low-damping characteristic to the outside; It should be noted that the IGCT inside the current interruption unit only needs to meet the current-carrying requirement, and the first diode D1, the second diode D2, the third diode D3, the fourth diode D4 and the SCR need to meet both the current-carrying requirement and the voltage withstand requirement; In the second aspect, the present application provides a control method for a high-voltage DC circuit breaker topology with a voltage regulation function. When the current flows to the right, the control timing is as Figure 2 shown, and the schematic diagram of the opening principle is as Figure 3 shown, including the following steps: Step S1: In the first stage, at time t0: A fault occurs in the DC transmission line, and the fault current rises rapidly until the protection device detects the fault current at time t1 and sends a tripping command to the fast mechanical switch MB; Step S2: In the second stage, at time t2: After the fast mechanical switch trips for 2 ms - 3 ms to reach an effective opening distance, conduction signals are respectively sent to the IGCT and SCR in the current interruption unit, and the commutation unit is put into operation. The current flow direction is shown in Figures 4(a) and 4(b); Step S3: Third stage, at time t3: The fault current in the current-carrying branch has completed all transfers. Subsequently, the fault current charges the capacitor C in the commutation unit through the current-intercepting unit, and the voltage across the capacitor C continuously increases. The current flow direction is shown in Fig. 4(c); Step S4: Fourth stage, at time t4: The voltage-regulating branch first reaches the threshold voltage and starts to operate. Part of the fault current is transferred to the voltage-regulating branch, and the rising rate of the capacitor voltage slightly slows down. Until time t5 when the energy-absorbing branch reaches the operating voltage, most of the current is transferred, and a small part of the current still flows through the voltage-regulating branch. The current flow directions are shown in Fig. 4(d) and Fig. 4(e); Step S5: At time t6, after detecting the operation of the energy-absorbing branch, a turn-off signal is sent to the current-intercepting unit. The IGCT in the current-intercepting unit turns off, and then the SCR turns off by itself. All the fault current is transferred to the energy-absorbing branch until the energy consumption is completed at time t7. The current flow direction is shown in Fig. 4(f); Step S6: After the fault current is cut off, the voltage-regulating branch is still in the working state, adjusting the capacitor C to the threshold voltage to prepare for reclosing interruption. At this time, the voltage polarity of the capacitor C is opposite to the initial state; Step S7: At time t8, the reclosing operation starts, closing the fast mechanical switch in the current-carrying branch (the fault still exists), and the fault current rapidly rises. Subsequently, steps S1 - S6 are performed.

[0023] It should be noted that in step S1, the conduction impedance of the HVDC circuit breaker is generally very small. The pre-stored energy voltage of the capacitor C in the commutation unit should satisfy at least providing 4 - 6 current zero-crossings. Therefore, it is required that the pre-stored energy voltage and the SMOV threshold voltage should satisfy: (1) where the damping angular frequency , r is the impedance of the DC transmission line; is the expected value of the fault current to be interrupted; L is the inductance of the commutation unit; t is the operation time of the commutation unit; U is the pre-stored energy voltage of the capacitor C, which is also the threshold voltage of the voltage-stabilizing lightning arrester; C is the capacitor of the commutation unit.

[0024] It should be noted that in step S2, since the circuit breaker is still in the high-voltage state, to prevent the IGCT in the current-intercepting unit from withstanding too high voltage, the SCR should be delayed to conduct after the IGCT conducts, and a certain number of voltage-sharing capacitors should be equipped; It should be noted that in step S5, the current that the IGCT in the current-intercepting unit needs to cut off is the current limited by the high-energy resistor R and the voltage-stabilizing lightning arrester SMOV. This current value satisfies: (2) Among them, represents the operating voltage of the energy absorption branch; is the threshold voltage of the voltage stabilizing arrester; is the steady-state impedance of the voltage stabilizing arrester, which is determined by the volt-ampere characteristic of the voltage stabilizing arrester itself; It should be noted that: in step S7, the time t8 generally requires a time interval of 300 ms after the time t7.

[0025] Among them, as shown in Figures 5(a) and 5(b), they are voltage-current waveform diagrams of a process of one opening, reclosing, and secondary opening (i.e., the reclosing interruption process). It can be seen from this that the high-voltage DC circuit breaker with voltage regulation function provided by this application has the reclosing interruption function.

[0026] Compared with the prior art, the beneficial effects brought by adopting the above technical solution are as follows: The voltage stabilizing arrester SMOV and the high-energy resistor R are connected in series to form a voltage regulation branch with an independent voltage regulation function, and are connected in parallel on both sides of the capacitor C. By using the special function of this module, the voltage of the capacitor C can be reduced to below the 1-10 mA reference voltage of the voltage stabilizing arrester SMOV within a short time, and part of the system energy caused by the fault during the interruption process can be absorbed. At the same time, the current interruption unit is used to cut off the small current generated by the action of the voltage regulation branch, reducing the number of fully controlled devices used; this design can be applied to any resonant high-voltage DC circuit breaker that uses a capacitor to establish a transient voltage as a commutation circuit, realizing capacitor voltage regulation to enable the circuit breaker to have the reclosing interruption function, and having good economy.

[0027] It should be understood that expressions such as "including" and "may include" that can be used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "including" and / or "having" can be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or a combination thereof, but cannot be interpreted as excluding the existence or possibility of addition of one or more other characteristics, numbers, operations, constituent elements, components, or a combination thereof.

[0028] In addition, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" can include A, can include B, or can include both A and B.

[0029] In the description of the embodiments of the present application, it should be noted that unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that the two are connected and the relative position relationship after connection remains unchanged. "Rotational connection" means that the two are connected and can rotate relative to each other after connection. "Sliding connection" means that the two are connected and can slide relative to each other after connection. The orientation terms mentioned in the embodiments of the present application, such as "top", "bottom", "inner", "outer", "left", "right", etc., are only references to the direction of the attached drawings. Therefore, the orientation terms are used to better and more clearly explain and understand the embodiments of the present application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the embodiments of the present application.

[0030] In addition, in the embodiments of the present application, mathematical concepts such as symmetry, equality, parallelism, and perpendicularity are mentioned. These limitations are all in view of the current technological level, rather than absolute strict definitions in the mathematical sense. A small deviation is allowed, and approximate symmetry, approximate equality, approximate parallelism, approximate perpendicularity, etc. are all acceptable. For example, when it is said that A is parallel to B, it means that A is parallel to B or approximately parallel to B, and the included angle between A and B can be between 0 degrees and 10 degrees. When it is said that A is perpendicular to B, it means that A is perpendicular to B or approximately perpendicular to B, and the included angle between A and B can be between 80 degrees and 100 degrees.

[0031] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A high voltage DC circuit breaker topology with voltage regulation function, characterized in that: include: A flow branch, a current conversion unit, a current interception unit, a voltage regulating branch and an energy absorption branch; both ends of the flow branch are respectively connected to the DC transmission line; One end of the commutation unit is connected to one end of the cutoff unit, and the other end is connected to one end of the energy absorption branch; the other end of the cutoff unit is connected to the other end of the energy absorption branch; the voltage regulating branch is connected in parallel to both sides of the capacitor in the commutation unit; The flow branch is used to conduct the rated current and disconnect when a fault occurs in the DC transmission line; the cut-off unit is used to connect the converter unit to the DC transmission line after the flow branch is disconnected; The commutation unit is used to generate high-frequency oscillating current and realize current transfer under fault conditions; the voltage regulating branch includes a voltage-stabilizing lightning arrester and a high-energy resistor connected in series, which are used to absorb the residual energy after the capacitor in the commutation unit establishes a transient voltage, so as to slow down the rate of rise of the capacitor voltage in the commutation unit and adjust the internal voltage of the capacitor to the voltage level required for disconnection; the energy absorption branch is used to absorb the residual energy of the DC transmission line and limit the overvoltage generated on the fast mechanical switch of the current-passing branch; the cut-off unit is used to disconnect the path between the commutation unit and the voltage regulating branch after detecting the action of the energy absorption branch, so as to cut off the current generated during the action of the voltage regulating branch.

2. The high voltage DC circuit breaker topology according to claim 1, characterized in that: The current cutoff unit comprises an inner layer composed of a plurality of integrated gate-controlled thyristors IGCT and a plurality of thyristors SCR connected in series, and an outer layer composed of a first diode, a second diode, a third diode and a fourth diode forming a bridge structure according to current flow direction.

3. The high voltage DC circuit breaker topology according to claim 1 or 2, characterized in that: The energy absorption branch is a number of lightning arresters.

4. The high voltage DC circuit breaker topology according to any one of claims 1 to 3, characterized in that: When the DC transmission line is put into operation for the first time, the capacitor of the commutation unit is charged with energy by an external charging device.

5. The high voltage DC circuit breaker topology according to claim 1, characterized in that: The pre-storage voltage of the capacitor in the commutation unit satisfies the requirement of providing at least 4 current zero crossing points, and the pre-storage voltage satisfies the threshold voltage of the voltage stabilizing arrester in the voltage regulating branch: Among them, the damping angular frequency , r is the impedance of the DC transmission line; is the fault current value expected to be interrupted; L is the inductance of the commutation unit; C is the capacitance value of the commutation unit; t The time for the commutation unit to be put into operation; U It is the pre-energy storage voltage of the capacitor in the commutation unit and also the threshold voltage of the voltage stabilizing arrester.

6. The high voltage DC circuit breaker topology according to claim 2, characterized in that: The current that the IGCT in the cutoff unit needs to cut off is: in, It represents the action voltage of the energy absorption branch; is the threshold voltage of the voltage stabilizing arrester; is the steady-state impedance of the voltage-stabilizing arrester; R It is a high energy resistor.

7. A control method for a high voltage DC circuit breaker topology based on any one of claims 1 to 6, characterized in that: The following steps are involved: Step S1: At time t0, when a fault occurs in the DC transmission line, the fault current rises rapidly until the fault current is detected at time t1, and a tripping command is issued to the fast mechanical switch in the current-carrying branch; Step S2: At time t2, after the fast mechanical switch opens to the effective breaking distance, it first sends a conduction signal to the IGCT in the cut-off unit, and then sends a conduction signal to the SCR to put the commutation unit into operation; Step S3: At time t3, the fault current in the current-carrying branch is completely transferred, and the fault current continuously charges the capacitor in the commutation unit through the current-cutting unit, so that the voltage across the capacitor continuously increases; Step S4: at time t4, when the voltage regulating branch reaches the threshold voltage and operates, part of the fault current is transferred to the voltage regulating branch to slow down the rate of increase of the capacitor voltage, until at time t5, when the energy absorption branch reaches the operating voltage and most of the fault current is transferred; Step S5: At time t6, when the energy absorption branch is detected to be in motion, a shut-off signal is sent to the current cut-off unit, first shutting off the current cut-off unit IGCT, and finally shutting off the SCR itself, transferring all the fault current to the energy absorption branch until the energy consumption is completed at time t7; Step S6: After the fault current is cut off, the voltage regulating branch continues to work to adjust the capacitor to the threshold voltage, in preparation for the reclosing switch to open.

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