Bidirectional current breaker and operation method thereof

Abstract

A bidirectional DC current breaker and an operation method thereof are disclosed. According to one embodiment of the present disclosure, a bidirectional DC current breaker is provided, the bidirectional DC current breaker comprising a first thyristor, a second thyristor, a first switch, a second switch, a capacitor, a first reactor, a second reactor, a first closing switch and a second closing switch, wherein: the capacitor is charged with a forward DC current supplied by turning on the first thyristor and the first switch; when a failure occurs in a load-side circuit, the capacitor is discharged and the first thyristor is turned off by a first reverse current induced in the first reactor; the capacitor is charged with a reverse DC current supplied by turning on the second thyristor and the second switch; and, when a failure occurs in a power-side circuit, the capacitor is discharged and the second thyristor is turned off by a second reverse current induced in the second reactor.

Description

Bidirectional current blocking device and method of operation thereof

[0001] The present disclosure relates to a bidirectional current blocking device and a method of operation thereof.

[0002] The following description merely provides background information related to the present embodiment and does not constitute prior art.

[0003] When a fault occurs in a DC system, the DC fault current rises rapidly, and the longer the interruption time, the larger the magnitude of the DC fault current that must be interrupted. Therefore, a DC circuit breaker capable of interrupting the DC fault current quickly is required.

[0004] DC circuit breakers using semiconductor devices with a turn-off function (e.g., IGBTs) have a very fast breaking speed. However, because they perform an opening operation by receiving a signal from a protective relay when a fault occurs, they cannot interrupt the DC fault current immediately upon the occurrence of the fault.

[0005] Semiconductor devices with turn-off functions (e.g., IGBTs) are expensive, and as the voltage and current increase, the size of the semiconductor device also increases, leading to higher device configuration costs. This makes it difficult to apply them to medium voltage (MV) or high voltage (HV) DC systems.

[0006] The present disclosure aims to solve the aforementioned problems by providing a bidirectional DC current blocking device using a thyristor and a commutation circuit that operates immediately upon the occurrence of a fault, and a method of operation thereof.

[0007] The problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by a person skilled in the art from the description below.

[0008] According to one embodiment of the present disclosure, a bidirectional DC current blocking device comprising a first thyristor, a second thyristor, a first switch, a second switch, a capacitor, a first reactor, a second reactor, a first switching switch, and a second switching switch is provided, wherein the capacitor is charged by a forward DC current supplied by turning on the first thyristor and the first switch, and when a fault occurs in the load-side circuit, the capacitor is discharged and the first thyristor is turned off by a first reverse current induced in the first reactor, and the capacitor is charged by a reverse DC current supplied by turning on the second thyristor and the second switch, and when a fault occurs in the power-side circuit, the capacitor is discharged and the second thyristor is turned off by a second reverse current induced in the second reactor.

[0009] The first thyristor and the second thyristor can be connected in parallel in a DC line.

[0010] One end of the first switch may be connected to one end of the capacitor and the other end of the first switch may be connected to one end of the second reactor, and one end of the second switch may be connected to one end of the capacitor and the other end of the second switch may be connected to the other end of the first reactor.

[0011] The other end of the above capacitor can be grounded.

[0012] One end of the first reactor is connected to the power side circuit of the DC line and the other end of the first reactor is connected to the positive electrode of the first thyristor and the negative electrode of the first thyristor, and one end of the second reactor is connected to the negative electrode of the first thyristor and the positive electrode of the second thyristor and the other end of the second reactor can be connected to the load side circuit of the DC line.

[0013] One end of the first input switch is connected to the other end of the second reactor and the load-side circuit, and the other end of the first input switch is grounded, and one end of the second input switch is connected to one end of the first reactor and the power-side circuit, and the other end of the second input switch can be grounded.

[0014] The first input switch and the second input switch may each include an Insulated Gate Bipolar Transistor (IGBT), a Wide Band Gap (WBG) semiconductor switch, a thyristor, a mechanical switch, or a Spark Gap switch.

[0015] The bidirectional DC current blocking device may further include a non-linear resistor element for suppressing the inrush voltage generated when the first thyristor or the second thyristor is turned off or for absorbing residual energy.

[0016] The above nonlinear resistance element can be connected in parallel to the first thyristor and the second thyristor.

[0017] The above nonlinear resistor may include a MOSA (Metal Oxide Surge Arrester) or a MOV (Metal Oxide Varistor).

[0018] According to an embodiment of the present disclosure, a fault current can be quickly interrupted.

[0019] According to an embodiment of the present disclosure, the design of a DC current interruption device can be simplified and the configuration cost reduced.

[0020] According to an embodiment of the present disclosure, a DC current interruption device can be easily applied to a medium voltage or high voltage DC system.

[0021] The effects of the present disclosure are not limited to those mentioned above, and other unmentioned effects will be clearly understood by a person skilled in the art from the description below.

[0022] FIG. 1 is a diagram showing the configuration of a bidirectional DC current blocking device according to one embodiment of the present disclosure.

[0023] FIGS. 2a to 2c are drawings for explaining the operation of a bidirectional DC current blocking device according to one embodiment of the present disclosure.

[0024] FIG. 3 is a diagram showing the configuration of a bidirectional DC current blocking device according to another embodiment of the present disclosure.

[0025] FIG. 4 is a flowchart of a method performed by a bidirectional DC current blocking device according to one embodiment of the present disclosure.

[0026] Some embodiments of the present disclosure are described in detail below with reference to exemplary drawings. It should be noted that in assigning reference numerals to the components of each drawing, the same components are given the same reference numeral whenever possible, even if they are shown in different drawings. Furthermore, in describing the present disclosure, if it is determined that a detailed description of related known components or functions could obscure the essence of the present disclosure, such detailed description is omitted.

[0027] In describing the components of the embodiments according to the present disclosure, symbols such as first, second, i), ii), a), b), etc., may be used. These symbols are intended only to distinguish the components from other components, and the essence, order, or sequence of the components is not limited by the symbols. When a part in the specification is described as 'comprising' or 'having' a component, this means that, unless explicitly stated otherwise, it does not exclude other components but may include additional components. Furthermore, terms such as 'part' or 'module' described in the specification refer to a unit that processes at least one function or operation, and this may be implemented in hardware, software, or a combination of hardware and software.

[0028] The detailed description set forth below, together with the accompanying drawings, is intended to describe exemplary embodiments of the present disclosure and is not intended to represent the only embodiment in which the present disclosure may be practiced.

[0029] In this specification, the term 'turn-on' may be used interchangeably with 'closed' or 'closed pole', and the term 'turn-off' may be used interchangeably with 'open' or 'open pole'.

[0030] In this specification, if one end of a specific element or circuit is the right end of the specific element or circuit, the other end of the specific element or circuit may be the left end of the specific element or circuit. If one end of a specific element or circuit is the left end of the specific element or circuit, the other end of the specific element or circuit may be the right end of the specific element or circuit.

[0031] In this specification, the term "one side" refers to the power source side in a DC system, and the term "other side" refers to the load side. This is for convenience of explanation and the present disclosure is not limited thereto.

[0032] In this specification, the term "forward direction" refers to the direction from the power source side to the load side in a DC system, and the term "reverse direction" refers to the direction from the load side to the power source side. This is for convenience of explanation and is not a limitation of the present disclosure.

[0033] The present disclosure relates to a bidirectional DC current interruption device and a method of operation thereof. Specifically, it provides a bidirectional DC current interruption technology using a thyristor and a commutation circuit that operates immediately upon the occurrence of a fault.

[0034] The bidirectional DC current blocking device according to the embodiments of the present disclosure is configured based on a thyristor, which is a turn-on element, and implements the turn-off of the thyristor using a commutation circuit composed of a capacitor and a reactor and a ground fault path created when a fault occurs in the DC system.

[0035] Since the thyristor is turned on by a gate signal and turned off immediately upon the occurrence of a fault such as a ground fault, the magnitude of the fault current to be interrupted is equal to the load current. Therefore, compared to DC interruption devices based on Insulated Gate Bipolar Transistors (IGBTs) that interrupt fault currents larger than the load current, there is an advantage in being able to keep the capacity of the device that absorbs switching surge voltage and residual energy of the DC system small.

[0036] In addition, thyristors have the advantage of being suitable for application in medium-voltage (MV) or high-voltage (HV) systems and high-current systems because they offer greater voltage and current capacity per unit compared to IGBTs.

[0037] FIG. 1 is a diagram showing the configuration of a bidirectional DC current blocking device according to one embodiment of the present disclosure.

[0038] Referring to FIG. 1, a bidirectional DC current blocking device (100) according to one embodiment of the present disclosure includes a first thyristor (111), a second thyristor (112), a first switch (121), a second switch (122), a capacitor (130), a first reactor (141), a second reactor (142), a first switching switch (151), and a second switching switch (152). The bidirectional DC current blocking device (100) may further include a control unit (not shown) that controls the overall operation of the components. For example, the control unit may generate a gate signal for turning on each thyristor and / or a signal for controlling the operation of each switch and each switching switch.

[0039] When normal operating current is supplied in the forward direction (e.g., from the power source side to the load side) in the DC line, the first thyristor (111) and the first switch (121) are kept in the turned-on state. The capacitor (130) is charged with the forward DC current. In response to a fault occurring in the load side circuit, the capacitor (130) is discharged, and the reverse current induced in the first reactor (141) is supplied to the first thyristor (111), causing the first thyristor (111) to turn off. Through this, the forward fault current is cut off. Additionally, the forward DC current supplied to the load side can be cut off by turning on the first switch (151).

[0040] When normal operating current is supplied in the reverse direction (e.g., from the load side to the power side) in the DC line, the second thyristor (112) and the second switch (122) remain in the turned-on state. The capacitor (130) is charged with the reverse DC current. In response to a fault occurring in the power side circuit, the capacitor (130) is discharged, and the reverse current induced in the second reactor (142) is supplied to the second thyristor (112), causing the second thyristor (112) to turn off. Through this, the reverse fault current is blocked. Additionally, the reverse DC current supplied to the power side can be blocked by turning on the second switch (152).

[0041] The first thyristor (111) is a semiconductor switching element and is turned on to supply a forward DC current. Turning off to cut off a forward fault current will be described later. The first thyristor (111) is installed between the first reactor (141) and the second reactor (142) in the DC line. The anode of the first thyristor (111) is connected to the other end of the first reactor (141), and the cathode is connected to one end of the second reactor (142).

[0042] The second thyristor (112) is a semiconductor switching element and is turned on to supply reverse DC current. Turning off to block reverse fault current will be described later. The second thyristor (112) is installed between the first reactor (141) and the second reactor (142) in the DC line. The second thyristor (112) is connected in parallel with the first thyristor (111). The negative terminal of the second thyristor (112) is connected to the other end of the first reactor (141), and the positive terminal is connected to one end of the second reactor (142).

[0043] The first switch (121) is turned on to supply a forward DC current. The first switch (121) is installed between the second reactor (142) and the capacitor (130). One end of the first switch (121) is connected to the capacitor (130), and the other end is connected to one end of the second reactor (142).

[0044] The second switch (122) is turned on to supply reverse DC current. The second switch (122) is installed between the first reactor (141) and the capacitor (130). One end of the second switch (122) is connected to the capacitor (130), and the other end is connected to the other end of the first reactor (141).

[0045] The capacitor (130) can be charged with a forward or reverse DC current. That is, the forward DC current supplied to the DC line can be supplied to the capacitor (130) through the first thyristor (111) and the first switch (121), and the capacitor (130) can be charged by the forward DC current. The reverse DC current supplied to the DC line can be supplied to the capacitor (130) through the second thyristor (112) and the second switch (122), and the capacitor (130) can be charged by the reverse DC current. The capacitor (130) is installed between the contact point where the first switch (121) and the second switch (122) are connected and ground. One end of the capacitor (130) is connected to one end of the first switch (121) and one end of the second switch (122), and the other end is grounded.

[0046] When a fault such as a ground fault occurs in the load-side circuit of the DC line, the capacitor (130), the first switch (121), the second reactor (142), and the ground fault path form a commutation circuit, and the capacitor (130) is discharged. When the capacitor (130) is discharged, a reverse current in the opposite direction to the forward DC current is induced through interaction such as mutual induction between the first reactor (141) and the second reactor (142). Specifically, a change in current in the second reactor (142) occurs due to the discharge of the capacitor (130). The change in current in the second reactor (142) generates an induced voltage in the first reactor (141). A reverse current is generated by the induced voltage and supplied to the first thyristor (111). Due to the reverse current, the current flowing between the positive and negative electrodes of the first thyristor (111) becomes zero, and the first thyristor (111) is turned off.

[0047] When a fault such as a ground fault occurs in the power side circuit of the DC line, the capacitor (130), the second switch (122), the first reactor (141), and the ground fault path form a commutation circuit, and the capacitor (130) is discharged. When the capacitor (130) is discharged, a reverse DC current and a reverse current in the opposite direction are induced through interaction such as mutual induction between the first reactor (141) and the second reactor (142). Specifically, a change in current in the first reactor (141) occurs due to the discharge of the capacitor (130). The change in current in the first reactor (141) generates an induced voltage in the second reactor (142). A reverse current is generated by the induced voltage and supplied to the second thyristor (112). Due to the reverse current, the current flowing between the positive and negative electrodes of the second thyristor (112) becomes zero, and the second thyristor (112) is turned off.

[0048] The first reactor (141) is connected to the power supply circuit in the DC line. One end of the first reactor (141) is connected to the power supply circuit, and the other end is connected to the positive terminal of the first thyristor (111) and the negative terminal of the second thyristor (112).

[0049] The second reactor (142) is connected between the DC line and the load-side circuit. One end of the second reactor (142) is connected to the negative terminal of the first thyristor (111) and the positive terminal of the second thyristor (112), and the other end is connected to the load-side circuit.

[0050] The first reactor (141) and the second reactor (142) are closely coupled to each other, so that magnetic or electrical interaction is possible between the two reactors.

[0051] The first input switch (151) can cut off the forward load current. The first input switch (151) maintains a turned-off state in a normal state, but can be turned on according to a control signal to cut off the forward load current. The first input switch (151) is installed between the other end of the second reactor (142) and ground. One end of the first input switch (151) is connected to the other end of the second reactor (142) and the load-side circuit, and the other end is grounded. The first input switch (151) may include various forms such as an IGBT, a WBG (Wide Band Gap) semiconductor switch, a thyristor, a mechanical switch, a spark gap switch, etc., but is not limited thereto.

[0052] The second input switch (152) can block reverse load current. The second input switch (152) maintains a turned-off state in a normal state, but can be turned on according to a control signal to block reverse load current. The second input switch (152) is installed between one end of the first reactor (141) and ground. One end of the second input switch (152) is connected to one end of the first reactor (141) and the power supply side circuit, and the other end is grounded. The second input switch (152) may include various forms such as an IGBT, a WBG (Wide Band Gap) semiconductor switch, a thyristor, a mechanical switch, a spark gap switch, etc., but is not limited thereto.

[0053] The operation of a bidirectional DC current interruption device according to embodiments of the present disclosure will be explained with reference to FIGS. 2a to 2c. FIGS. 2a to 2c illustrate the operation of the bidirectional DC current interruption device when a DC current is supplied in the forward direction, but it should be understood that it operates on the same principle when a DC current is supplied in the reverse direction.

[0054] First, a charging process for the capacitor (130) is required.

[0055] Referring to FIG. 2a, in the normal state, the first thyristor (111) and the first switch (121) remain in the turned-on state and allow a forward DC current (IN) and a capacitor charging current (IC) to flow. The capacitor (130) is charged with the capacitor charging current (IC).

[0056] FIG. 2b illustrates a situation in which an accident, such as a ground fault, occurs in the load-side circuit of a DC line. Referring to FIG. 2b, as the capacitor (130) discharges, a discharge current (IC) is generated, and a reverse current (IMI) is induced due to interaction, such as mutual induction between the first reactor (141) and the second reactor (142). Due to the reverse current, the current flowing between the positive and negative electrodes of the first thyristor (111) becomes zero, and the first thyristor (111) is turned off.

[0057] Referring to FIG. 2c, the first thyristor (111) is turned off, and the forward fault current is cut off.

[0058] Meanwhile, when the switching surge voltage of the first thyristor (111) or the second thyristor (112) is large and the residual energy of the DC system is large after the fault current is cut off, it is necessary to absorb the residual energy. To this end, the bidirectional DC current cutoff device may further include a separate energy absorption element.

[0059] FIG. 3 is a diagram showing the configuration of a bidirectional DC current blocking device according to another embodiment of the present disclosure.

[0060] Referring to FIG. 3, a bidirectional DC current blocking device (100) according to another embodiment of the present disclosure includes a first thyristor (111), a second thyristor (112), a first switch (121), a second switch (122), a capacitor (130), a first reactor (141), a second reactor (142), a first input switch (151), a second input switch (152), and a non-linear resistance element (160). That is, a bidirectional DC current blocking device (100) according to another embodiment of the present disclosure includes all the same components as FIG. 1 and further includes a non-linear resistance element (160).

[0061] The first thyristor (111), second thyristor (112), first switch (121), second switch (122), capacitor (130), first reactor (141), second reactor (142), first input switch (151), and second input switch (152) shown in FIG. 3 are identical to the components shown in FIG. 1.

[0062] A nonlinear resistor element (160) is connected in parallel to the first thyristor (111) and the second thyristor (112) to protect the system from the transient inrush voltage (TIV) that occurs when the first thyristor (111) or the second thyristor (112) is turned off and to absorb residual energy. The nonlinear resistor element (160) may include a Metal Oxide Surge Arrester (MOSA) or a Metal Oxide Varistor (MOV).

[0063] FIG. 4 is a flowchart of a method performed by a bidirectional DC current blocking device according to one embodiment of the present disclosure. FIG. 4 describes, by way of example, a method performed by a bidirectional DC current blocking device when a DC current is supplied in the forward direction, but it should be understood that it operates on the same principle when a DC current is supplied in the reverse direction.

[0064] Referring to FIG. 4, the capacitor (130) is charged through the DC current flowing through the DC line when the first thyristor (111) and the first switch (121) are turned on (S410).

[0065] When a fault such as a ground fault occurs in the load-side circuit of the DC line, a ground fault path is created and the capacitor (130) is discharged (S420).

[0066] When the capacitor (130) is discharged, a reverse current is generated through interaction such as mutual induction between the first reactor (141) and the second reactor (142), and the current flowing between the positive and negative electrodes of the first thyristor (111) becomes zero due to the reverse current.

[0067] The DC current blocking operation is completed as the first thyristor (111) is turned off (S440).

[0068] Each component of the device or method according to the present invention may be implemented in hardware or software, or in a combination of hardware and software. Additionally, the function of each component may be implemented in software, and a microprocessor may be implemented to execute the function of the software corresponding to each component.

[0069] Various embodiments of the systems and techniques described herein may be realized as digital electronic circuits, integrated circuits, field programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include being implemented as one or more computer programs executable on a programmable system. A programmable system comprises a storage system, at least one input device, and at least one programmable processor (which may be a special-purpose processor or a general-purpose processor) coupled to receive data and instructions from and transmit data and instructions to at least one output device. Computer programs (which are also known as programs, software, software applications, or code) include instructions for the programmable processor and are stored on a "computer-readable recording medium."

[0070] Computer-readable recording media include all types of recording devices in which data that can be read by a computer system is stored. Such computer-readable recording media may be non-volatile or non-transitory media such as ROM, CD-ROM, magnetic tape, floppy disk, memory card, hard disk, magneto-optical disk, and storage device, and may also include transitory media such as data transmission media. Additionally, computer-readable recording media may be distributed across networked computer systems, and computer-readable code may be stored and executed in a distributed manner.

[0071] Although the flowcharts and timing diagrams in this specification describe each process as being executed sequentially, this is merely an illustrative explanation of the technical concept of one embodiment of the present disclosure. In other words, a person skilled in the art to which one embodiment of the present disclosure belongs may modify and adapt the flowcharts and timing diagrams in various ways, such as changing the order described in the flowcharts and timing diagrams or executing one or more of the processes in parallel, without departing from the essential characteristics of one embodiment of the present disclosure; therefore, the flowcharts and timing diagrams are not limited to a chronological order.

[0072] The above description is merely an illustrative explanation of the technical concept of the present embodiment, and a person skilled in the art to which the present embodiment belongs would be able to make various modifications and variations within the scope of the essential characteristics of the present embodiment. Accordingly, the present embodiments are intended to explain, not limit, the technical concept of the present embodiment, and the scope of the technical concept of the present embodiment is not limited by these embodiments. The scope of protection of the present embodiment shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of the present embodiment.

[0073] (Explanation of symbols)

[0074] 111: 1st Thyrister

[0075] 112: Second Thyrister

[0076] 121: First switch

[0077] 122: Second switch

[0078] 130: Capacitor

[0079] 141: Reactor 1

[0080] 142: Second Reactor

[0081] 151: First insertion switch

[0082] 152: Second input switch

[0083] 160: Non-linear resistive element

[0084] Statements regarding sponsored research or development

[0085] This invention is the result of research conducted in 2024 with funding from the Ministry of Trade, Industry and Energy and support from the Korea Institute of Energy Technology Evaluation and Planning (Project No.: 2410002771, Project Name: Development of DC Circuit Breaker Technology for Extra-High Voltage DC Distribution).

[0086] CROSS-REFERENCE TO RELATED APPLICATION

[0087] This patent application claims priority to Korean patent application No. 10-2024-0156899 filed on November 7, 2024, the entire contents of which are incorporated into this patent application by reference.

Claims

1. A bidirectional DC current blocking device comprising a first thyristor, a second thyristor, a first switch, a second switch, a capacitor, a first reactor, a second reactor, a first switching switch, and a second switching switch, wherein The capacitor is charged by a forward DC current supplied by turning on the first thyristor and the first switch, and when a fault occurs in the load-side circuit, the capacitor is discharged and the first thyristor is turned off by a first reverse current induced in the first reactor. A bidirectional DC current blocking device in which the capacitor is charged by a reverse DC current supplied by turning on the second thyristor and the second switch, and when a fault occurs in the power supply circuit, the capacitor is discharged and the second thyristor is turned off by a second reverse current induced in the second reactor.

2. In Paragraph 1, The first thyristor and the second thyristor are connected in parallel in a DC line, and One end of the first switch is connected to one end of the capacitor and the other end of the first switch is connected to one end of the second reactor, and one end of the second switch is connected to one end of the capacitor and the other end of the second switch is connected to the other end of the first reactor, and The other end of the above capacitor is grounded, and One end of the first reactor is connected to the power side circuit of the DC line and the other end of the first reactor is connected to the positive electrode of the first thyristor and the negative electrode of the first thyristor, and one end of the second reactor is connected to the negative electrode of the first thyristor and the positive electrode of the second thyristor and the other end of the second reactor is connected to the load side circuit of the DC line. A bidirectional DC current blocking device in which one end of the first input switch is connected to the other end of the second reactor and the load-side circuit and the other end of the first input switch is grounded, one end of the second input switch is connected to one end of the first reactor and the power-side circuit and the other end of the second input switch is grounded.

3. In Paragraph 1, A bidirectional DC current blocking device in which a change in current of the second reactor due to the discharge of the capacitor induces a voltage in the first reactor, and the first reverse current is generated by the induced voltage.

4. In Paragraph 1, A bidirectional DC current blocking device in which a change in current of the first reactor due to the discharge of the capacitor induces a voltage in the second reactor, and the second reverse current is generated by the induced voltage.

5. In Paragraph 1, A bidirectional DC current blocking device wherein the first input switch and the second input switch each comprise an Insulated Gate Bipolar Transistor (IGBT), a Wide Band Gap (WBG) semiconductor switch, a thyristor, a mechanical switch, or a Spark Gap switch.

6. In Paragraph 1, It further includes a non-linear resistor element for suppressing the inrush voltage generated when the first thyristor or the second thyristor is turned off or for absorbing residual energy, and The above nonlinear resistance element is a bidirectional DC current blocking device connected in parallel to the first thyristor and the second thyristor.

7. In Paragraph 6, The above nonlinear resistor element is a bidirectional DC current blocking device comprising a MOSA (Metal Oxide Surge Arrester) or MOV (Metal Oxide Varistor).

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