CN117374894A - Novel Z-source direct current breaker and working method thereof - Google Patents

Novel Z-source direct current breaker and working method thereof Download PDF

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Publication number
CN117374894A
CN117374894A CN202311298697.0A CN202311298697A CN117374894A CN 117374894 A CN117374894 A CN 117374894A CN 202311298697 A CN202311298697 A CN 202311298697A CN 117374894 A CN117374894 A CN 117374894A
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China
Prior art keywords
direct current
parallel
circuit
diode
breaker
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CN202311298697.0A
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Inventor
李季
吕文涛
王鑫
邵磊
刘宏利
李超
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Tianjin University of Technology
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Tianjin University of Technology
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Priority to CN202311298697.0A priority Critical patent/CN117374894A/en
Publication of CN117374894A publication Critical patent/CN117374894A/en
Pending legal-status Critical Current

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
    • H02H3/087—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current for dc applications
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Driving Mechanisms And Operating Circuits Of Arc-Extinguishing High-Tension Switches (AREA)

Abstract

The invention discloses a novel Z-source direct current breaker, which consists of a parallel Z-source direct current breaker unit, a breaker work protection unit and an alternating current/direct current isolation unit, wherein a grounded capacitance branch circuit formed by connecting a diode and a resistor in parallel is added, so that the common grounding between power supply electric loads can be realized, and the novel Z-source direct current breaker has the functions of fault follow current and protection components; the diode added on the output side of the power supply can ensure that current does not flow back to the direct current power supply under the condition of direct current fault; corresponding working processes can be completed according to the circuit structure in a steady-state stage, a direct-current load line fault, a fault transient stage, a fault steady-state stage and a diode freewheel stage; the invention has simple structure and easy operation method, can restrain the amplitude of fault current, has smaller capacity of the needed device, can quickly clear DC fault, and has smaller capacity of the needed device for cutting off the short-circuit current with the same level.

Description

Novel Z-source direct current breaker and working method thereof
(one) technical field:
the invention relates to the technical field of low-voltage electrical control, in particular to a novel Z-source direct-current circuit breaker and a working method thereof.
(II) background art:
as energy economies continue to reform, power demand presents a rapidly growing trend. The direct current breaker is used as one of important electrical components in the power system, and can reliably and rapidly cut off the circuit when the circuit is overloaded, short-circuited and other faults occur, so as to protect the electrical distribution network and industrial equipment from being damaged. If the faults cannot be cleared timely, equipment of the converter station can be damaged, and certain damage can be brought to the power generation unit.
Conventional dc circuit breakers, such as a cross-type Z-source, a parallel-type Z-source, and a series-type Z-source circuit breaker, have a problem in that a maximum short-circuit current is large. Symmetry Z source, T source and series-connected T source circuit breaker have the problem that transient time is longer etc.. Therefore, in order to enable the direct current breaker to exert better fault isolation effect, the invention provides a novel Z-source direct current breaker structure.
(III) summary of the invention:
the invention aims to provide a novel Z-source direct current breaker and a working method thereof, which can overcome the defects of the prior art, and is a breaker with a simple structure and the working method is easy to realize.
The technical scheme of the invention is as follows: the novel Z-source direct current breaker is characterized by comprising a parallel Z-source direct current breaker unit, a breaker work protection unit and an alternating current/direct current isolation unit; the circuit breaker work protection unit is connected with the parallel Z-source direct current circuit breaker unit in parallel, one end of the parallel Z-source direct current circuit breaker unit is directly connected with the alternating current-direct current isolation unit, and the other end of the parallel Z-source direct current circuit breaker unit is connected with the negative end of the power supply; the other end of the alternating current-direct current isolation unit is connected with the positive end of the power supply.
The parallel Z-source direct current breaker unit consists of a series-parallel circuit I, a series-parallel circuit II, a resistor R3, a capacitor C1, a capacitor C2, a capacitor C3 and a controllable thyristor SCR; one end of the series-parallel circuit I is connected with the alternating current-direct current isolation unit, and the other end of the series-parallel circuit I is connected with the anode of the controllable thyristor SCR; one end of the series-parallel circuit II is connected with the cathode of the controllable thyristor SCR, and the other end of the series-parallel circuit II is respectively connected with the capacitor C3 and the resistor R3; the capacitor C1 is connected in parallel with two ends of the series-parallel circuit I and the controllable thyristor SCR which are connected in series; the capacitor C2 is connected in parallel with two ends of the series-parallel circuit II and the controllable thyristor SCR which are connected in series; the capacitor C3 and the resistor R3 are connected in parallel, one end of the capacitor C3 and the resistor R3 after being connected in parallel is connected with the series-parallel circuit II, and the other end of the capacitor C3 and the resistor R3 are connected with the negative end of the power supply.
The series-parallel circuit I is composed of an inductor L1, a diode D2 and a resistor R1; the positive end of the diode D2 is connected with the resistor R1 in series, and the two are connected with the inductor L1 in parallel after being connected in series; the negative electrode end of the diode D2 is connected with the alternating current-direct current isolation unit; the other end of the resistor R1 is connected with the anode of the controllable thyristor SCR.
The series-parallel circuit II consists of an inductor L2, a diode D3 and a resistor R2; the positive end of the diode D3 is connected with the resistor R2 in series, and the diode D3 and the resistor R2 are connected in parallel with the inductor L2 after being connected in series; the negative electrode end of the diode D3 is connected with the cathode of the controllable thyristor SCR; the other end of the resistor R2 is connected with one end of a parallel circuit formed by the capacitor C3 and the resistor R3.
The circuit breaker work protection unit is composed of a resistor R4, a capacitor C4 and a diode D4; the resistor R4 and the diode D4 are in parallel connection; one end of the capacitor C4 is connected with the negative electrode end of the diode D2 in the parallel Z-source direct current breaker unit, and the other end of the capacitor C4 is connected with the negative electrode end of the diode D4; the positive terminal of the diode D4 is connected with the negative terminal of the power supply, and the parallel structure of the breaker work protection unit and the parallel Z-source direct current breaker unit is realized.
The alternating current/direct current isolation unit is composed of a diode D1; the positive terminal of the diode D1 is connected with the positive terminal of the power supply, and the negative terminal of the diode D1 is connected with the negative terminal of the diode D2 in the parallel Z-source direct current breaker unit.
The working method of the novel Z-source direct current breaker is characterized by comprising the following working conditions:
(1) When the direct current load circuit fails, short-circuit current flows to the grounding circuit through a failure point and flows to the grounding capacitor C4 through the freewheeling diode D4; at this time, since the diode D1 is turned off reversely, the fault current cannot flow into the dc power supply, and it will flow through the capacitor C1, the thyristor SCR and the capacitor C2 in the right circuit, thereby forming a closed loop circuit;
(2) When a direct current load circuit breaks down, currents flowing into the inductors L1 and L2 in the parallel Z-source direct current breaker unit slowly change due to the characteristics of the current, and currents of the capacitors C1 and C2 in the parallel Z-source direct current breaker unit suddenly increase until the currents are equal to the inductor currents, so that the controllable thyristor SCR is turned off to realize fault isolation;
(3) When the novel Z-source direct current breaker operates in a steady-state process, current flows into a direct current load through a diode D1, an inductor L1, a controllable thyristor SCR and an inductor L2;
(4) When the novel Z-source direct current breaker operates in a fault transient process and the direct current load is short-circuited, the controllable thyristor SCR is not completely closed, and short-circuit current flows through the diode D4 of the grounding circuit, the capacitors C1, C2 and C4 and the controllable thyristor SCR to form a closed-loop circuit, so that the duration time is short;
(5) When the novel Z-source direct current breaker operates in a fault steady-state process, the controllable thyristor SCR is completely disconnected, and a short-circuit current flows through the diode D4 of the grounding circuit and then passes through a passage formed by the inductor L1 and the capacitor C2; the capacitor C1 and the inductor L2 form a passage through which the two branch circuits flow into a fault point to form a closed-loop circuit; meanwhile, the inductance current in the parallel Z-source direct current breaker unit is equal to the capacitance current under the condition;
(6) When the novel Z-source direct current breaker operates in a diode follow current stage, the LC discharge circuit finishes discharging, and the currents of the capacitors C1 and C2 in the parallel Z-source direct current breaker unit are reduced to 0; however, due to the freewheeling effect of the parallel-branched diodes D2, D3, the current through the inductors L1, L2 will remain at the initial value.
The working principle of the invention is as follows: the novel Z-source direct current breaker comprises a parallel Z-source direct current breaker unit, a breaker work protection unit and an alternating current/direct current isolation unit; one end of the breaker work protection unit is connected with the input end of the parallel Z-source direct current breaker unit, and the other end of the breaker work protection unit is connected with the negative end of the power supply; the negative polarity end of the alternating current-direct current isolation unit is connected with the input end of the parallel Z-source direct current breaker unit, and the positive polarity end of the alternating current-direct current isolation unit is connected with the positive terminal of the power supply.
The circuit breaker work protection unit can realize the public ground between the power supply electric loads, and wherein resistance R4 mainly is used for protecting diode D4, and diode D4 mainly is used for trouble freewheel, and the AC/DC isolation unit that the power side is newly added ensures that the electric current can not flow back DC power supply under the condition of taking place direct current trouble. The parallel Z-source direct current breaker unit can prevent damage caused by direct current load line faults in a direct current system.
The invention has the advantages that: the structure is simple, the cost is low, and the cost performance is high; the common grounding between the power supply and the load can be realized through the circuit breaker work protection unit, so that the function of effectively inhibiting the amplitude of fault current by using a device with smaller capacity is realized; the parallel Z-source direct current breaker unit can realize the rapid clearing of direct current faults, and the capacity of devices required for cutting off the short-circuit current with the same level is smaller.
(IV) description of the drawings:
fig. 1 is a schematic diagram of an overall circuit structure of a novel Z-source dc breaker according to the present invention.
Fig. 2 is a schematic diagram of a flow path of a short-circuit current when a dc load line fails in a working method of the novel Z-source dc circuit breaker according to the present invention.
Fig. 3 is a schematic diagram of a current flow path during a steady state phase in a method of operating a novel Z source dc circuit breaker according to the present invention.
Fig. 4 is a schematic diagram of a current flow path during a transient phase of a fault in the working method of the novel Z-source dc circuit breaker according to the present invention.
Fig. 5 is a schematic diagram of a current flow path in a fault steady-state stage in the working method of the novel Z-source dc circuit breaker according to the present invention.
Fig. 6 is a schematic diagram of a current flow path of a diode during a freewheeling stage in a method of operating a novel Z-source dc circuit breaker according to the present invention.
(V) the specific embodiment:
examples: the technical solutions in the embodiments of the present invention will be described in detail and clearly with reference to the accompanying drawings in the embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
As shown in figure 1, the novel Z-source direct current breaker is characterized by comprising a parallel Z-source direct current breaker unit, a breaker work protection unit and an alternating current/direct current isolation unit; the circuit breaker work protection unit is connected with the parallel Z-source direct current circuit breaker unit in parallel, one end of the parallel Z-source direct current circuit breaker unit is directly connected with the alternating current-direct current isolation unit, and the other end of the parallel Z-source direct current circuit breaker unit is connected with the negative end of the power supply; the other end of the alternating current-direct current isolation unit is connected with the positive end of the power supply.
As shown in fig. 1, the novel Z source dc breaker is characterized in that the parallel Z source dc breaker unit is composed of a series-parallel circuit I, a series-parallel circuit II, a resistor R3, a capacitor C1, a capacitor C2, a capacitor C3, and a controllable thyristor SCR; one end of the series-parallel circuit I is connected with one end of the alternating current-direct current isolation unit and one end of the breaker work protection unit, and the other end of the series-parallel circuit I is connected with the anode of the controllable thyristor SCR; one end of the series-parallel circuit II is connected with the cathode of the controllable thyristor SCR, and the other end of the series-parallel circuit II is respectively connected with the capacitor C3 and the resistor R3; the capacitor C1 is connected in parallel with two ends of the series-parallel circuit I and the controllable thyristor SCR which are connected in series; the capacitor C2 is connected in parallel with two ends of the series-parallel circuit II and the controllable thyristor SCR which are connected in series; the capacitor C3 and the resistor R3 are connected in parallel, one end of the capacitor C3 and the resistor R3 after being connected in parallel is connected with the series-parallel circuit II, and the other end of the capacitor C3 and the resistor R3 are connected with the negative end of the power supply.
The series-parallel circuit I is composed of an inductor L1, a diode D2 and a resistor R1; the positive end of the diode D2 is connected with the resistor R1 in series, and the two are connected with the inductor L1 in parallel after being connected in series; the negative electrode end of the diode D2 is connected with one end of the AC/DC isolation unit and one end of the breaker work protection unit; the other end of the resistor R1 is connected with the anode of the controllable thyristor SCR.
The series-parallel circuit II consists of an inductor L2, a diode D3 and a resistor R2; the positive end of the diode D3 is connected with the resistor R2 in series, and the diode D3 and the resistor R2 are connected in parallel with the inductor L2 after being connected in series; the negative electrode end of the diode D2 is connected with the cathode of the controllable thyristor SCR; the other end of the resistor R2 is connected with one end of a parallel circuit formed by the capacitor C3 and the resistor R3.
The parallel Z-source direct current breaker unit can prevent damage caused by direct current load line faults in a direct current system.
As shown in fig. 1, the circuit breaker operation protection unit is composed of a resistor R4, a capacitor C4 and a diode D4.
The resistor R4 and the diode D4 in the circuit breaker work protection unit are in parallel connection; one end of the capacitor C4 is connected with the negative electrode end of the diode D2 in the parallel Z-source direct current breaker unit, and the other end of the capacitor C4 is connected with the negative electrode end of the diode D4; the positive terminal of the diode D4 is connected with the negative terminal of the power supply, so that the parallel structure of the breaker work protection unit and the parallel Z-source direct current breaker unit is realized.
The circuit breaker work protection unit can realize common grounding between power supply electric loads.
The diode D4 is mainly used for fault freewheeling.
The resistor R4 is mainly used for protecting the diode D4.
As shown in fig. 1, the ac/dc isolation unit is composed of a diode D1.
The positive terminal of the diode D1 in the AC/DC isolation unit is connected with the positive terminal of the power supply, and the negative terminal of the diode D1 in the parallel Z-source DC breaker unit is connected with the negative terminal of the diode D2.
The alternating current-direct current isolation unit is mainly used for ensuring that current does not flow back to the direct current power supply under the condition of direct current fault.
As shown in fig. 2, 3, 4, 5 and 6, the novel Z-source direct current breaker is a working principle diagram of the novel Z-source direct current breaker in different stages.
The working method of the circuit breaker is as follows:
as shown in fig. 2, when the dc load line fails, the short-circuit current flows to the ground circuit through the failure point and flows to the ground capacitor C4 through the flywheel diode D4; at this time, due to the reverse turn-off of the diode D1, the fault current cannot flow into the dc power supply, and it will flow through the capacitor C1, the thyristor SCR and the capacitor C2 in the right side circuit, thereby forming a closed loop circuit.
As shown in fig. 2, when the dc load line fails, the current flowing into the inductors L1 and L2 in the parallel Z-source dc breaker unit changes slowly due to its own characteristics, and the current of the capacitors C1 and C2 in the parallel Z-source dc breaker unit increases suddenly until the current is equal to the inductor current, so that the controllable thyristor SCR turns off to realize fault isolation.
As shown in fig. 3, when the novel Z-source dc breaker operates in a steady state process, current flows into a dc load through the diode D1, the inductor L1, the controllable thyristor SCR and the inductor L2.
As shown in fig. 4, when the novel Z source dc breaker operates in a fault transient process, the controllable thyristor SCR is not completely turned off when the dc load is shorted, and the shorted current flows through the diode D4, the capacitors C1, C2, C4 and the controllable thyristor SCR of the ground circuit to form a closed loop circuit, which has a short duration.
As shown in fig. 5, when the novel Z source dc breaker operates in a fault steady-state process, the controllable thyristor SCR is completely turned off, and a short-circuit current flows through the diode D4 of the ground circuit, and then passes through a path formed by the inductor L1 and the capacitor C2; the capacitor C1 and the inductor L2 form a passage through which the two branch circuits flow into a fault point to form a closed-loop circuit; meanwhile, in this case, the inductance current in the parallel type Z-source direct current breaker unit is equal to the capacitance current.
As shown in fig. 6, when the novel Z source dc breaker operates in the diode freewheeling stage, the LC discharge circuit has completed discharging, and the currents of the capacitors C1, C2 in the parallel Z source dc breaker unit drop to 0; however, due to the freewheeling effect of the parallel-branched diodes D2, D3, the current through the inductors L1, L2 will remain at the initial value.
The novel Z-source direct current breaker is simple in structure, low in cost and high in cost performance.
The novel Z-source direct current circuit breaker can realize public grounding between a power supply and a load through the circuit breaker work protection unit, and the function of effectively inhibiting the fault current amplitude by using a device with smaller capacity is realized.
The parallel Z-source direct current breaker unit can realize the rapid clearing of direct current faults, and the capacity of devices required for cutting off the same level of short-circuit current is smaller.
The foregoing is merely a preferred design of the present application and is not intended to limit the present application, and various modifications and variations may be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims (7)

1. The novel Z-source direct current breaker is characterized by comprising a parallel Z-source direct current breaker unit, a breaker work protection unit and an alternating current/direct current isolation unit; the circuit breaker work protection unit is connected with the parallel Z-source direct current circuit breaker unit in parallel, one end of the parallel Z-source direct current circuit breaker unit is directly connected with the alternating current-direct current isolation unit, and the other end of the parallel Z-source direct current circuit breaker unit is connected with the negative end of the power supply; the other end of the alternating current-direct current isolation unit is connected with the positive end of the power supply.
2. The novel Z-source direct current breaker according to claim 1, wherein the parallel Z-source direct current breaker unit is composed of a series-parallel circuit I, a series-parallel circuit II, a resistor R3, a capacitor C1, a capacitor C2, a capacitor C3 and a controllable thyristor SCR; one end of the series-parallel circuit I is connected with one end of the alternating current-direct current isolation unit and one end of the breaker work protection unit, and the other end of the series-parallel circuit I is connected with the anode of the controllable thyristor SCR; one end of the series-parallel circuit II is connected with the cathode of the controllable thyristor SCR, and the other end of the series-parallel circuit II is respectively connected with the capacitor C3 and the resistor R3; the capacitor C1 is connected in parallel with two ends of the series-parallel circuit I and the controllable thyristor SCR which are connected in series; the capacitor C2 is connected in parallel with two ends of the series-parallel circuit II and the controllable thyristor SCR which are connected in series; the capacitor C3 and the resistor R3 are connected in parallel, one end of the capacitor C3 and the resistor R3 after being connected in parallel is connected with the series-parallel circuit II, and the other end of the capacitor C3 and the resistor R3 are connected with the negative end of the power supply.
3. The novel Z-source direct current breaker according to claim 2, wherein the series-parallel circuit I is composed of an inductor L1, a diode D2 and a resistor R1; the positive end of the diode D2 is connected with the resistor R1 in series, and the two are connected with the inductor L1 in parallel after being connected in series; the negative electrode end of the diode D2 is connected with one end of the AC/DC isolation unit and one end of the breaker work protection unit; the other end of the resistor R1 is connected with the anode of the controllable thyristor SCR.
4. The novel Z-source direct current breaker according to claim 2, wherein the series-parallel circuit II is composed of an inductor L2, a diode D3 and a resistor R2; the positive end of the diode D3 is connected with the resistor R2 in series, and the diode D3 and the resistor R2 are connected in parallel with the inductor L2 after being connected in series; the negative electrode end of the diode D3 is connected with the cathode of the controllable thyristor SCR; the other end of the resistor R2 is connected with one end of a parallel circuit formed by the capacitor C3 and the resistor R3.
5. The novel Z-source direct current circuit breaker according to claim 4, wherein the circuit breaker work protection unit is composed of a resistor R4, a capacitor C4 and a diode D4; the resistor R4 and the diode D4 are in parallel connection; one end of the capacitor C4 is connected with the negative electrode end of the diode D2 in the parallel Z-source direct current breaker unit, and the other end of the capacitor C4 is connected with the negative electrode end of the diode D4; the positive terminal of the diode D4 is connected with the negative terminal of the power supply, and the parallel structure of the breaker work protection unit and the parallel Z-source direct current breaker unit is realized.
6. The novel Z-source direct current breaker according to claim 4, wherein the alternating current-direct current isolation unit is composed of a diode D1; the positive terminal of the diode D1 is connected with the positive terminal of the power supply, and the negative terminal of the diode D1 is connected with the negative terminal of the diode D2 in the parallel Z-source direct current breaker unit.
7. The working method of the novel Z-source direct current breaker is characterized by comprising the following working conditions:
(1) When the direct current load circuit fails, short-circuit current flows to the grounding circuit through a failure point and flows to the grounding capacitor C4 through the freewheeling diode D4; at this time, since the diode D1 is turned off reversely, the fault current cannot flow into the dc power supply, and it will flow through the capacitor C1, the thyristor SCR and the capacitor C2 in the right circuit, thereby forming a closed loop circuit;
(2) When a direct current load circuit breaks down, currents flowing into the inductors L1 and L2 in the parallel Z-source direct current breaker unit slowly change due to the characteristics of the current, and currents of the capacitors C1 and C2 in the parallel Z-source direct current breaker unit suddenly increase until the currents are equal to the inductor currents, so that the controllable thyristor SCR is turned off to realize fault isolation;
(3) When the novel Z-source direct current breaker operates in a steady-state process, current flows into a direct current load through a diode D1, an inductor L1, a controllable thyristor SCR and an inductor L2;
(4) When the novel Z-source direct current breaker operates in a fault transient process and the direct current load is short-circuited, the controllable thyristor SCR is not completely closed, and short-circuit current flows through the diode D4 of the grounding circuit, the capacitors C1, C2 and C4 and the controllable thyristor SCR to form a closed-loop circuit, so that the duration time is short;
(5) When the novel Z-source direct current breaker operates in a fault steady-state process, the controllable thyristor SCR is completely disconnected, and a short-circuit current flows through the diode D4 of the grounding circuit and then passes through a passage formed by the inductor L1 and the capacitor C2; the capacitor C1 and the inductor L2 form a passage through which the two branch circuits flow into a fault point to form a closed-loop circuit; meanwhile, the inductance current in the parallel Z-source direct current breaker unit is equal to the capacitance current under the condition;
(6) When the novel Z-source direct current breaker operates in a diode follow current stage, the LC discharge circuit finishes discharging, and the currents of the capacitors C1 and C2 in the parallel Z-source direct current breaker unit are reduced to 0; however, due to the freewheeling effect of the parallel-branched diodes D2, D3, the current through the inductors L1, L2 will remain at the initial value.
CN202311298697.0A 2023-10-09 2023-10-09 Novel Z-source direct current breaker and working method thereof Pending CN117374894A (en)

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Application Number Priority Date Filing Date Title
CN202311298697.0A CN117374894A (en) 2023-10-09 2023-10-09 Novel Z-source direct current breaker and working method thereof

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Application Number Priority Date Filing Date Title
CN202311298697.0A CN117374894A (en) 2023-10-09 2023-10-09 Novel Z-source direct current breaker and working method thereof

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Publication Number Publication Date
CN117374894A true CN117374894A (en) 2024-01-09

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