DC circuit breaker, DC circuit breaker control device, DC circuit breaker control method, and program

Abstract

A direct current breaking device according to an embodiment has a main breaker and a ladder circuit. The main breaker is inserted into a direct current line. The ladder circuit is connected in parallel to the main breaker. The ladder circuit has two or more stile parts, and a rung part. In the two or more stile parts, three or more branch sections are connected in series. The rung part is interposed between nodes corresponding to each other among nodes of the branch sections in the two or more stile parts. Two or more of the branch sections each include a switch. The rung part includes an electric storage section.

Description

[Technical field]

[0001] An embodiment of the present invention relates to a DC circuit breaker, a control device for a DC circuit breaker, a control method for a DC circuit breaker, and a program. [Background technology]

[0002] In recent years, high-voltage DC circuit breakers (hereinafter simply referred to as "DC circuit breakers") have been developed to realize high-voltage DC transmission. Some DC circuit breakers include a main circuit breaker that breaks an accident that occurs on a DC line, and a commutation circuit (also called a resonant circuit) that supplies a high-frequency current that cancels the current flowing through the main circuit breaker (see, for example, Patent Document 1). This system is called a forced arc-extinguishing system. This type of DC circuit breaker includes a system that performs high-speed reclosing, and conventional DC circuit breakers of the forced arc-extinguishing system that breaks an accident after high-speed reclosing include a technology that includes multiple resonant circuits (see, for example, Patent Document 2) and a technology that includes a bridge circuit as a resonant circuit (see, for example, Patent Document 3).

[0003] However, in the case of a technique using multiple resonant circuits, the number of resonant circuits increases, which hinders the device from being compact, and in the case of a technique using a bridge circuit, multiple switches that can withstand the full voltage of the capacitor are required, which also hinders the device from being compact. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 58-34525 [Patent Document 2] Patent No. 6328356 [Patent Document 3] Patent No. 6509466 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a DC circuit breaker, a control device for a DC circuit breaker, a control method for a DC circuit breaker, and a program that can be made compact in structure. [Means for solving the problem]

[0006] The DC circuit breaker of the embodiment has a main circuit breaker and a ladder circuit. The main circuit breaker is inserted into a DC line. The ladder circuit is connected in parallel to the main circuit breaker. The ladder circuit has two or more vertical beams and a cross beam. The two or more vertical beams have three or more branches connected in series. The cross beams are interposed between corresponding nodes among the nodes between the branches in each of the two or more vertical beams. A plurality of the branch portions include switches. The cross beam includes a power storage unit. [Brief description of the drawings]

[0007] [Figure 1] 1 is a circuit diagram of a DC circuit breaker 100. [Diagram 2] FIG. 2 is a diagram showing a plurality of examples of the auxiliary circuit unit 2 arranged side by side. [Diagram 3] 2 is a diagram showing multiple examples of branch portions 5 in a ladder circuit portion 3 lined up. FIG. [Figure 4] FIG. 13 is a circuit diagram showing an embodiment of a cross piece. [Diagram 5] 1 is a diagram showing an example of a circuit configuration of a DC circuit breaker 100. [Figure 6] 3 is a diagram showing an example of operating waveforms in the DC circuit breaker 100 controlled by the control unit 101. [Figure 7] A graph showing the time changes in current Ib and voltage Vb when reverse current is superimposed using a full cross-piece capacitor. [Figure 8] A graph showing the changes in current Ib and voltage Vb over time when a reverse current is superimposed using a portion of the entire cross piece capacitor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, a DC circuit breaker, a control device for a DC circuit breaker, a control method for a DC circuit breaker, and a program according to the embodiments will be described with reference to the drawings. In the following description, components having the same or similar functions are designated by the same reference numerals. Duplicate descriptions of those components may be omitted.

[0009] 1 is a circuit diagram of a DC circuit breaker 100. The DC circuit breaker 100 includes, for example, a main circuit breaker 1, an auxiliary circuit unit 2, a ladder circuit unit 3, and a control unit 101. The auxiliary circuit unit 2 and the ladder circuit unit 3 are connected in parallel to the main circuit breaker 1. The auxiliary circuit unit 2 may be omitted depending on the configurations of the main circuit breaker 1 and the ladder circuit unit 3.

[0010] The main circuit breaker 1 includes, for example, a vacuum circuit breaker. The main circuit breaker 1 may include, for example, a gas circuit breaker, or may be configured by combining a vacuum circuit breaker and a gas circuit breaker. A saturable reactor may be connected in series to the main circuit breaker 1. The number of saturable reactors may be one or more. The DC circuit breaker 100 may include an energy absorption unit. In this case, the vacuum circuit breaker or the gas circuit breaker may be connected in parallel to each or more of the energy absorption units. The energy absorption unit is a unit that absorbs excess energy, for example, power. The energy absorption unit is configured, for example, as a lightning arrester (MOSA: Metal Oxide Surge Arrestors) in which zinc oxide (ZnO) elements are combined in series and in parallel. The zinc oxide elements in the lightning arrester may be connected only in series or only in parallel.

[0011] The main circuit breaker 1 may include, for example, a plurality of circuit breaking units, each of which may include a circuit in which at least one of the vacuum circuit breakers or the gas circuit breakers and the energy absorption unit are connected in parallel to each other. The circuit breaking unit may further include a voltage dividing circuit connected in parallel to at least one of the vacuum circuit breakers or the gas circuit breakers and the energy absorption unit. In this case, the voltage dividing circuit may be, for example, a circuit that operates to evenly or unevenly divide the inter-pole voltage generated between the poles of the vacuum circuit breakers or the gas circuit breakers in the plurality of circuit breaking units.

[0012] The multiple saturable reactors are connected in series, for example. A power supply source, such as a power plant, is connected to the left side of the main circuit breaker 1, and a load is connected to the right side. In the following description, the side to which the power supply source is connected is referred to as the upstream side, and the side to which the load is connected is referred to as the downstream side.

[0013] 2 is a diagram showing an arrangement of a number of examples of the auxiliary circuit section 2. The auxiliary circuit section 2 is configured, for example, by combining a reactor 21 and an energy absorption unit 22. The auxiliary circuit section 2 may be either the reactor 21 or the energy absorption unit 22, or may be configured by combining a number of these.

[0014] 2 as a first example includes two reactors 21 and one energy absorption unit 22. The two reactors 21 are respectively arranged in a wiring connecting the upstream side of the main circuit breaker 1 and the upstream side of the ladder circuit section 3, and in a wiring connecting the downstream side of the main circuit breaker 1 and the downstream side of the ladder circuit section 3. One end of the energy absorption unit 22 is connected to a wiring connecting the main circuit breaker 1 and the reactor 21 arranged in the wiring connecting the upstream side of the main circuit breaker 1 and the upstream side of the ladder circuit section 3, and the other end of the energy absorption unit 22 is connected to a wiring connecting the ladder circuit section 3 and the reactor 21 arranged in the wiring connecting the downstream side of the main circuit breaker 1 and the downstream side of the ladder circuit section 3.

[0015] 2 as a second example includes two reactors 21 and one energy absorption unit 22. The two reactors 21 are arranged in series in a wiring that connects the upstream side of the main circuit breaker 1 and the upstream side of the ladder circuit unit 3. One end of the energy absorption unit 22 is connected to the wiring that connects the two reactors 21, and the other end of the energy absorption unit 22 is connected to a wiring that connects the downstream side of the main circuit breaker 1 and the downstream side of the ladder circuit unit 3.

[0016] 2 as a third example includes one reactor 21 and one energy absorption unit 22. The reactor 21 is disposed in the wiring connecting the upstream side of the main circuit breaker 1 and the upstream side of the ladder circuit unit 3. One end of the energy absorption unit 22 is connected to the wiring connecting the reactor 21 and the upstream side of the main circuit breaker 1, and the other end of the energy absorption unit 22 is connected to the wiring connecting the downstream side of the main circuit breaker 1 and the downstream side of the ladder circuit unit 3.

[0017] 2 as a fourth example, includes two reactors 21 and one energy absorption unit 22. The two reactors 21 are respectively arranged in a wiring connecting the upstream side of the main circuit breaker 1 and the upstream side of the ladder circuit section 3, and in a wiring connecting the downstream side of the main circuit breaker 1 and the downstream side of the ladder circuit section 3. One end of the energy absorption unit 22 is connected to a wiring connecting the ladder circuit section 3 and the reactor 21 arranged in the wiring connecting the upstream side of the main circuit breaker 1 and the upstream side of the ladder circuit section 3, and the other end of the energy absorption unit 22 is connected to a wiring connecting the ladder circuit section 3 and the reactor 21 arranged in the wiring connecting the downstream side of the main circuit breaker 1 and the downstream side of the ladder circuit section 3.

[0018] 2 as a fifth example includes only one reactor 21. The reactor 21 is provided in the wiring connecting the upstream side of the main circuit breaker 1 and the upstream side of the ladder circuit unit 3. The sixth auxiliary circuit unit 2F illustrated sixth from the left in Fig. 2 includes only one energy absorption unit 22. One end of the energy absorption unit 22 is connected to the wiring connecting the upstream side of the main circuit breaker 1 and the upstream side of the ladder circuit unit 3, and the other end of the energy absorption unit 22 is connected to the wiring connecting the downstream side of the main circuit breaker 1 and the downstream side of the ladder circuit unit 3.

[0019] The auxiliary circuit unit 2 may be used alone or in combination of one or more of the above-mentioned first auxiliary circuit unit 2A to sixth auxiliary circuit unit 2F. The above-mentioned first auxiliary circuit unit 2A to sixth auxiliary circuit unit 2F may have their connections to the main circuit breaker 1 and the ladder circuit unit 3 reversed, may be reversed left to right on the page, or parallel parts may be connected in series or series parts may be connected in parallel.

[0020] The ladder circuit section 3 includes, for example, two or more, for example, two vertical wood sections 4. The two vertical wood sections 4 include, for example, three or more branches 5 connected in series. A node 6 is formed between each of the adjacent branches 5. The two vertical wood sections 4 have the same number of branches 5 and nodes 6.

[0021] A crosspiece 7 is connected between corresponding nodes 6 in each of the two vertical pieces 4. The corresponding nodes 6 are, for example, nodes that are arranged at positions in the same order counting from the same side in the two vertical pieces 4. For example, two or more crosspieces 7 are provided in the ladder circuit section 3.

[0022] 3 is a diagram showing a plurality of examples of the branch sections 5 in the ladder circuit section 3. The branch section 5 is formed by combining, for example, some or all of the switch 51, the reactor 52, the resistor 53, and the capacitor 54. The branch section 5 may be, for example, any one of the switch 51, the reactor 52, the resistor 53, and the capacitor 54, or may be formed by combining a plurality of these. The switch 51 may be any one of a gap switch, a vacuum switch, a gas switch, and a semiconductor element, or may be formed by combining a plurality of these. The branch section 5 may not be connected to some circuit elements such as a reactor, a resistor, a capacitor, and a switch.

[0023] A first branch 5A shown as a first example on the far left of Fig. 3 is composed of only a switch 51. A second branch 5B shown as a second example on the second side from the left of Fig. 3 is composed of a switch 51 and a reactor 52 connected in series. A third branch 5C shown as a third example on the third side from the left of Fig. 3 is composed of a resistor 53 and a capacitor 54 both connected in parallel to the switch 51 and reactor 52 connected in series.

[0024] A fourth branch 5D shown as a fourth example and fourth from the left in Fig. 3 is configured by connecting a reactor 52 in series to one end side of a switch 51, a resistor 53, and a capacitor 54 connected in parallel. A fifth branch 5E shown as a fifth example and fifth from the left in Fig. 3 is configured by connecting a reactor 52 in series to one end side of a switch 51 and a capacitor 54 connected in parallel.

[0025] A sixth branch 5F shown as a sixth example, sixth from the left in Fig. 3, is configured by connecting a capacitor 54 in parallel to a switch 51 and a reactor 52 connected in series. A seventh branch 5G shown as a seventh example, seventh from the left in Fig. 3, is configured by connecting a resistor 53 and a capacitor 54 in parallel.

[0026] The number of branches 5 (switches 51) provided in the ladder circuit section 3 is plural, but for example, if only the first interruption and the second interruption after reclosing are considered, four or more are required. In addition, by providing six or more branches 5 (switches 51) in the ladder circuit section 3, the magnitude of the current input from the ladder circuit section 3 to the main circuit breaker 1 can be changed.

[0027] Furthermore, although there are two or more vertical wooden sections 4 in the ladder circuit section 3, if only the first interruption and the second interruption after reclosing are considered, it is necessary to provide two or more branch sections 5 (switches 51) on each vertical wooden section 4. Furthermore, by providing three or more branch sections 5 (switches 51) on each vertical wooden section 4, the magnitude of the current input from the ladder circuit section 3 to the main circuit breaker 1 can be changed.

[0028] 4 is a diagram showing a number of examples of the cross piece 7 lined up. The cross piece 7 is formed by combining, for example, some or all of a capacitor 71, a reactor 72, and an energy absorption unit 73. The cross piece 7 may be, for example, any one of the capacitor 71, the reactor 72, and the energy absorption unit 73, or may be formed by combining a number of these. A charging circuit such as a pre-charging circuit for the capacitor 71 may also be provided. The capacitor 71 is an example of a power storage unit.

[0029] The first cross piece 7A shown as a first example on the far left of Fig. 4 is equipped with a capacitor 71. The second cross piece 7B shown as a second example on the second left of Fig. 4 is configured with a capacitor 71 and a reactor 72 connected in series. The third cross piece 7C shown as a third example on the third left of Fig. 4 is configured with a capacitor 71 and an energy absorption unit 73 connected in parallel.

[0030] The fourth cross piece 7D shown as the fourth example at number 4 from the left in Fig. 4 is configured with an energy absorption unit 73 connected in parallel to a capacitor 71 and a reactor 72 connected in series. The fifth cross piece 7E shown as the fifth example at number 5 from the left in Fig. 4 is configured with a reactor 72 connected in series to a capacitor 71 and an energy absorption unit 73 connected in parallel.

[0031] The control unit 101 can control the switching of the main circuit breaker 1 and the switch 51 included in the ladder circuit unit 3. The control unit 101 performs the switching control by, for example, a hardware processor such as a CPU (Central Processing Unit) (computer) executing a program (software). The control unit 101 may perform the switching control by hardware (including a circuit unit; circuitry) such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a GPU (Graphics Processing Unit), or may perform the switching control by cooperation between software and hardware. The program may be stored in a storage device (a storage device having a non-transient storage medium) such as an HDD or flash memory of the controller in advance, or may be stored in a removable storage medium such as a DVD or CD-ROM, and installed in the storage device by mounting the storage medium (non-transient storage medium) in a drive device. The program may be stored in the storage unit.

[0032] For example, when a fault current occurs as a current to be cut off due to a lightning strike or the like, the control unit 101 cuts off the location where the fault current occurred from the system, and then performs high-speed reclosing to quickly reconnect the system. When the main circuit breaker 1 cuts off the system and then reconnects it, the control unit 101 superimposes a current on the fault current flowing through the main circuit breaker 1. The control unit 101 controls the switch 51 to change any one of the direction, frequency, and magnitude of the current to be superimposed on the fault current flowing through the main circuit breaker 1. When a charging circuit such as a pre-charging circuit for the capacitor 71 is provided, the control unit 101 may be responsible for controlling the charging.

[0033] Next, an operation of the DC circuit breaker 100 controlled by the control unit 101 will be described. The operation of the DC circuit breaker 100 will be described using the DC circuit breaker 100 in which the configurations of the auxiliary circuit unit 2 and the ladder circuit unit 3 are specifically specified. FIG. 5 is a diagram showing an example of the circuit configuration of the DC circuit breaker 100.

[0034] The DC circuit breaker 100 shown in Fig. 5 is obtained by specifically specifying the configurations of the auxiliary circuit unit 2 and the ladder circuit unit 3 in the DC circuit breaker 100 shown in Fig. 1. Prior to describing the operation of the DC circuit breaker 100, the configuration of the DC circuit breaker 100 in which the configurations of the auxiliary circuit unit 2 and the ladder circuit unit 3 are specifically specified will be described below.

[0035] The DC circuit breaking device 100 shown in Fig. 5 includes the third auxiliary circuit section 2C shown in Fig. 2 as the auxiliary circuit section 2. The third auxiliary circuit section 2C includes a reactor 21 and an energy absorption unit 22. The ladder circuit section 3 of the DC circuit breaking device 100 includes three vertical wood sections 4, namely, a first vertical wood section 4a to a third vertical wood section 4c.

[0036] As each branch 5 of the first vertical wood portion 4a and the second vertical wood portion 4b, the first branch 5A shown in FIG. 3 is selected. The first branch 5A includes only a switch 51. As each branch 5 of the third vertical wood portion 4c sandwiched between the first vertical wood portion 4a and the second vertical wood portion 4b, the seventh branch 5G shown in FIG. 3 is selected. The seventh branch 5G includes a resistor 53 and a capacitor 54. As the cross wood portion 7, the first cross wood portion 7A shown in FIG. 4 is selected. The first cross wood portion 7A includes a capacitor 71.

[0037] In the following description, the switches 51 included in the branch 5 of the first vertical wood part 4a are referred to as the first switch 51a, the third switch 51c, the fifth switch 51e, the seventh switch 51g, and the ninth switch 51i, in order from the upstream side. Also, the switches 51 included in the branch 5 of the second vertical wood part 4b are referred to as the second switch 51b, the fourth switch 51d, the sixth switch 51f, the eighth switch 51h, and the tenth switch 51j, in order from the upstream side.

[0038] The capacitors 71 included in the cross piece 7 arranged between the first vertical piece 4a and the third vertical piece 4c are designated, in order from the upstream side, as the first capacitor 71a, the third capacitor 71c, the fifth capacitor 71e, and the seventh capacitor 71g. The capacitors 71 included in the cross piece 7 arranged between the second vertical piece 4b and the third vertical piece 4c are designated, in order from the upstream side, as the second capacitor 71b, the fourth capacitor 71d, the sixth capacitor 71f, and the eighth capacitor 71h.

[0039] FIG. 6 is a diagram showing an example of operating waveforms in the DC circuit breaker 100 controlled by the control unit 101. Before the system is interrupted, the first switch 51a to the tenth switch 51j are all in an open state. The first capacitor 71a to the eighth capacitor 71h (hereinafter, all cross-piece capacitors) are all charged with the arrows Y1 to Y8 in FIG. 6 being positive. The all cross-piece capacitors are charged, for example, via a pre-charging circuit (not shown). The resistor 53 and capacitor 54 selected as the branch of the third vertical wood 4c play a role in improving voltage sharing against, for example, DC voltage, lightning impulse voltage, and switching surge voltage.

[0040] When an accident occurs in the DC system, the control unit 101 closes an appropriate switch among the first switch 51a to the tenth switch 51j to the "closed" state. Here, a control by the control unit 101 when a fault current flowing through the main circuit breaker 1 due to an accident becomes a current Ib and flows in the direction of the arrow Y11 in FIG. 5 will be described.

[0041] For example, if an accident occurs at time t1, the control unit 101 detects this and opens the main circuit breaker 1 at time t2. For example, if the main circuit breaker 1 is a gas circuit breaker or a vacuum circuit breaker, after the main circuit breaker 1 is opened, a current-carrying state is maintained by arc discharge until a current zero point is formed in the main circuit breaker 1 and current interruption is completed.

[0042] Next, at time t3, the first switch 51a, the fourth switch 51d, the fifth switch 51e, the eighth switch 51h, and the ninth switch 51i (hereinafter, the first group switches) are closed. Of the first group switches, the first switch 51a, the fifth switch 51e, and the ninth switch 51i are odd-numbered switches in the first vertical wood part 4a, and the fourth switch 51d and the eighth switch 51h are even-numbered switches in the second vertical wood part 4b.

[0043] At this time, the second switch 51b, the third switch 51c, the sixth switch 51f, the seventh switch 51g, and the tenth switch 51j (hereinafter, second group switches) are kept "open". Among the second group switches, the third switch 51c and the seventh switch 51g are even-numbered switches in the first vertical wood part 4a, and the second switch 51b, the sixth switch 51f, and the tenth switch 51j are odd-numbered switches in the second vertical wood part 4b. The pattern in which the first group switches are "closed" and the second group switches are "open" is an example of a first opening and closing pattern.

[0044] By closing the first group switch, charge is released from each of the pre-charged all cross piece capacitors to a loop including the first group switch, all cross piece capacitors, reactor 21, and main circuit breaker 1.

[0045] As electric charge is released from each of the cross piece capacitors, a resonant current flows from each of the cross piece capacitors through the first group switch, reactor 21, and main circuit breaker 1. As a result, in the DC circuit breaker 100, an oscillating current in the opposite direction to the direction of current Ib, which is the fault current, is superimposed on the fault current. The direction in which current Ib flows is an example of one direction. The opposite direction to the direction in which current Ib flows is an example of a reverse direction. As a result, the main circuit breaker 1 fulfills its breaking duty by completing the current interruption when a current zero point is formed.

[0046] When the fault current is forcibly interrupted by such control, electromagnetic energy may remain in the system. This residual electromagnetic energy charges the crosspiece capacitor and is processed by the energy absorption unit 22. When the first group switch is closed at time t3 and a current zero point is formed in the main circuit breaker 1, the fault current becomes current Ir and flows in the commutation circuit excluding the main circuit breaker 1, as shown by arrow Y21.

[0047] The current Ir due to the fault current flowing through the commutation circuit charges all the cross-piece capacitors in the opposite direction to the direction in which they were previously charged while the first group switch is "closed." If we ignore the voltage induced in the reactor 21, the sum of the charging voltages of all the cross-piece capacitors is approximately equal to the voltage Vb across the main circuit breaker 1, and the energy absorption unit 22 starts processing energy from the time when Vb rises to a certain voltage value.

[0048] After the first group switch is closed at time t3, it is opened again at a suitable time t4 before it is reclosed. By opening the first group switch again at time t4, the current flowing to all the cross piece capacitors is cut off, and the charging voltage Vc of all the cross piece capacitors can be maintained at a voltage value required for further accident handling.

[0049] The DC circuit breaker 100 closes the main circuit breaker 1 again to perform high speed reclosing at time t4. If the fault continues, the fault current will flow again in the main circuit breaker 1 after high speed reclosing. At this time, the direction of the current Ib, which is the fault current, will be the same as the direction of the first fault current before high speed reclosing was performed.

[0050] The control unit 101 detects that the current Ib is flowing again, and at time t5, the main circuit breaker 1 is again opened to perform a fault shutdown (hereinafter, the second fault shutdown). In the second fault shutdown, the energized state is maintained by the arc discharge until a current zero point is formed in the main circuit breaker 1, as in the first fault shutdown when the main circuit breaker 1 is opened (hereinafter, the first fault shutdown).

[0051] Next, at time t6, the second group switch is closed and the first group switch is left open. By closing the second group switch, the electric charge from the all cross piece capacitors, which was charged to the reverse polarity by the first fault interruption, is discharged to the loop including the second group switch, all cross piece capacitors, reactor 21, and main circuit breaker 1.

[0052] As a result of all the cross-piece capacitors releasing electric charge, a resonant current flows from each of the cross-piece capacitors through the second group switches, the reactor 21, and the main circuit breaker 1. As a result, in the DC circuit breaker 100, an oscillating current in the opposite direction to the fault current Ib is superimposed on the fault current. As a result, the main circuit breaker 1 fulfills its breaking duty by forming a current zero point and completing the current breaking. Thereafter, it processes the electromagnetic energy remaining in the system in the same way as in the first fault breaking.

[0053] In addition, when the current Ib, which is the fault current flowing through the main circuit breaker 1 due to a fault, flows in the opposite direction to the direction of the arrow in Fig. 6, the control unit 101 closes the second group switch and keeps the first group switch open as the first fault cutoff. The pattern in which the first group switch is open and the second group switch is closed is an example of the second opening and closing pattern. By closing the second group switch, electric charge is discharged from each of the pre-charged cross piece capacitors to the loop including the second group switch, all cross piece capacitors, reactor 21, and main circuit breaker 1.

[0054] As a result of the discharge of electric charge from each of the cross piece capacitors, a resonant current flows from each of the cross piece capacitors through the second group switch, the reactor 21, and the main circuit breaker 1. As a result, in the DC circuit breaker 100, an oscillating current in the opposite direction to the fault current is superimposed on the fault current. As a result, the main circuit breaker 1 fulfills its breaking duty by forming a current zero point and completing the current breaking. After that, it processes the electromagnetic energy remaining in the system.

[0055] Subsequently, if fault breaking becomes necessary again after the reclosing, the first group switch is set to "closed" and a second fault breaking is performed in the same manner as when the processing of the first group switch and the second group switch is switched when the current Ib flows in the direction of the arrow in Figure 6. After that, the electromagnetic energy remaining in the system is processed.

[0056] When the control unit 101 cannot detect or predict the direction of the current Ib, which is the fault current, it closes either the first group switch or the second group switch to superimpose an oscillating current on the main circuit breaker 1. In this case, the main circuit breaker 1 is configured so that the interruption is successful whether the oscillating current forms a current zero point in the main circuit breaker 1 in the first half wave or in the second half wave.

[0057] The above explanation has been given of a case where interruption is successful at the first current zero point formed in the main circuit breaker 1 by the resonant current superimposed on the main circuit breaker 1 from the commutation circuit. In contrast, there are cases where the main circuit breaker 1 fails to interrupt the current at the first current zero point, but succeeds at the second current zero point or the third current zero point.

[0058] Next, the operation when a load current is interrupted as the current to be interrupted will be described. When a fault current is interrupted, all the cross piece capacitors release the electric charge that had been charged, but when a load current is interrupted, some of the all the cross piece capacitors release the electric charge that had been charged. The control unit 101 adjusts the switch 51 to be closed based on the magnitude or direction, or both, of the load current flowing through the main circuit breaker 1. Here, an example will be described in which the fifth capacitor 71e and the sixth capacitor 71f among all the cross piece capacitors release the electric charge.

[0059] When a current Ib, which is a load current, flows in the direction of an arrow Y11 in Fig. 6, the control unit 101 that has received a cutoff command closes, for example, the first switch 51a, the third switch 51c, the fifth switch 51e, the eighth switch 51h, and the tenth switch 51j (hereinafter, the third group switches) and keeps the second switch 51b, the fourth switch 51d, the sixth switch 51f, the seventh switch 51g, and the ninth switch 51i (hereinafter, the fourth group switches) open. As a result, in the main circuit breaker 1, electric charges are discharged from the fifth capacitor 71e and the sixth capacitor 71f to a loop including the third group switches, the fifth capacitor 71e and the sixth capacitor 71f that are charged in advance, the reactor 21, and the main circuit breaker 1.

[0060] As electric charges are discharged from the fifth capacitor 71e and the sixth capacitor 71f, a resonant current flows from each of the fifth capacitor 71e and the sixth capacitor 71f through the third group switch, the reactor 21, and the main circuit breaker 1. As a result, in the DC circuit breaker 100, an oscillating current in the opposite direction to the load current Ib is superimposed on the load current. As a result, a current zero point is formed in the main circuit breaker 1. By opening the main circuit breaker 1 at an appropriate time before the current zero point is formed in the main circuit breaker 1, the main circuit breaker 1 completes current interruption at the time when the current zero point is formed, and fulfills its interruption duty.

[0061] When a load current Ib flows in the opposite direction to the direction of the arrow Y11 in Fig. 6, the control unit 101 receives a cutoff command and closes, for example, the fourth group switch and leaves the third group switch open. As a result, electric charges are discharged from the fifth capacitor 71e and the sixth capacitor 71f to the loop including the fourth group switch, the fifth capacitor 71e and the sixth capacitor 71f that are charged in advance, the reactor 21, and the main circuit breaker 1.

[0062] As electric charges are discharged from the fifth capacitor 71e and the sixth capacitor 71f, a resonant current flows from the fifth capacitor 71e and the sixth capacitor 71f through the fourth group switch, the reactor 21, and the main circuit breaker 1. As a result, in the DC circuit breaker 100, an oscillating current in the opposite direction to the load current is superimposed on the load current. As a result, a current zero point is formed in the main circuit breaker 1. By opening the main circuit breaker 1 at an appropriate time before the current zero point is formed in the main circuit breaker 1, the main circuit breaker 1 completes current interruption at the time when the current zero point is formed, and fulfills its interruption duty.

[0063] Next, we will explain the relationship between the time change of the current Ib flowing through the main circuit breaker 1 and the voltage Vb applied to the main circuit breaker 1 when the main circuit breaker 1 interrupts the load current. Here, we will explain the case where a reverse current is superimposed on the load current flowing through the main circuit breaker 1 using all the cross-piece capacitors, and the case where a reverse current is superimposed on the load current flowing through the main circuit breaker 1 using part of the all the cross-piece capacitors.

[0064] FIG. 7 shows the changes in current Ib and voltage Vb over time when a reverse current is superimposed using the entire cross piece capacitor, and FIG. 8 shows the changes in current Ib and voltage Vb over time when a reverse current is superimposed using a portion of the entire cross piece capacitor.

[0065] When a reverse current is superimposed using some of the cross-piece capacitors, the voltage Vb applied to the main circuit breaker 1 is smaller than when a reverse current is superimposed using all of the cross-piece capacitors. Therefore, when a reverse current is superimposed using some of the cross-piece capacitors, the transient recovery voltage applied to the main circuit breaker 1 after the current zero point can be made smaller than when a reverse current is superimposed using all of the cross-piece capacitors. This reduces the interrupting duty of the main circuit breaker 1, thereby reducing the risk of interrupting failure.

[0066] Furthermore, when the fault current interrupted by the main circuit breaker 1 is small, the DC circuit breaker 100 may reduce the number of capacitors 71 used to release the reverse current superimposed on the fault current in the main circuit breaker 1. By reducing the magnitude of the reverse current superimposed on the fault current in the main circuit breaker 1, the magnitude of the transient recovery voltage applied to the main circuit breaker 1 after the current zero point also becomes smaller.

[0067] This reduces the interruption load of the main circuit breaker 1 and reduces the risk of circuit breaking failure. However, in order to form a current zero point in the main circuit breaker 1 even if the fault current flows again after high speed reclosing, the control unit 101 is required to appropriately select the switch 51 to be "closed" and to maintain a sufficient charging voltage to form a current zero point with the connected capacitor 71.

[0068] The DC circuit breaker 100 of the embodiment includes a ladder circuit section 3 connected in parallel to the main circuit breaker 1, the vertical section 4 in the ladder circuit section 3 includes three or more switches 51, and the horizontal section 7 includes a capacitor 71. Therefore, when the main circuit breaker 1 is "closed" again after performing a first fault interruption, if the fault current is flowing again in the main circuit breaker 1, a second fault interruption is performed.

[0069] When the DC circuit breaker 100 performs a first fault interruption, it stores power for a second fault interruption in the capacitor 71, enabling high-speed reclosing. The circuit that superimposes current on the main circuit breaker 1 during high-speed reclosing is the ladder circuit unit 3. Since the DC circuit breaker 100 includes the ladder circuit unit 3, it is not necessary to provide multiple resonant circuits as in the technology disclosed in Patent Document 2.

[0070] In addition, since a bridge circuit is not provided as in the technology disclosed in Patent Document 3, there is no need to provide multiple switches that can withstand the full voltage of the capacitor. In this way, since there is no need to provide multiple resonant circuits or multiple switches that can withstand the full voltage of the capacitor, the entire device can be made more compact. Therefore, without providing an additional resonant circuit, it is possible to handle the interruption of small currents including load currents and large currents due to accidents while also handling the operating duties of high-speed reclosing on DC lines.

[0071] In addition, in the bridge-type forced arc-extinguishing DC circuit breaker disclosed in Patent Document 3, it is difficult to control the magnitude and frequency characteristics of the current superimposed on the main circuit breaker from the bridge circuit, making it difficult to interrupt load currents or small-scale fault currents.

[0072] In this regard, the DC circuit breaker 100 of the embodiment can reduce the number of capacitors 71 used to release the reverse current superimposed on the fault current in the main circuit breaker 1. Therefore, it is possible to easily handle interruption of the load current and interruption of a small-scale fault current.

[0073] According to at least one of the embodiments described above, the DC circuit breaking device comprises a main circuit breaker inserted into a DC line and a ladder circuit connected in parallel to the main circuit breaker, the ladder circuit comprising two or more vertical beam sections having three or more branches connected in series, and a cross beam section interposed between corresponding nodes among the nodes between the branches in each of the two or more vertical beam sections, wherein a plurality of the branches include switches and the cross beam section includes a power storage unit, thereby making it possible to make the structure compact.

[0074] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0075] 1...Main circuit breaker, 2 (2A to 2F)...Auxiliary circuit section, 3...Ladder circuit section, 4 (4a to 4c)...Vertical section, 5 (5A to 5G)...Branch section, 6...Node, 7 (7A to 7E) Horizontal section, 21, 52, 72...Reactor, 22, 73...Energy absorption unit, 51 (51a to 51j)...Switch, 53...Resistor, 54, 71 (71a to 71h)...Capacitor, 100...DC circuit breaker, 101...Control section

Claims

1. A main circuit breaker that is inserted in a DC line and through which a current to be interrupted flows in one direction and in a reverse direction; a ladder circuit connected in parallel to the main breaker, The ladder circuit includes two or more vertical wooden members each having three or more branches connected in series; and a horizontal piece interposed between the nodes of the branches of each of the two or more vertical pieces, the nodes being corresponding to each other; A plurality of the branches include a switch; The cross piece includes a storage unit. DC circuit breaker.

2. Further comprising an auxiliary circuit connected in parallel to the main breaker. The DC circuit breaker according to claim 1 .

3. The branch portion further includes at least one of a reactor, a capacitor, or a resistor. The DC circuit breaker according to claim 1 or 2.

4. The cross piece further includes at least one of a reactor or an energy absorption unit. The DC circuit breaker according to any one of claims 1 to 3.

5. The switch includes at least one of a gap switch, a vacuum switch, a gas switch, or a semiconductor element; A DC circuit breaker according to any one of claims 1 to 4.

6. The DC circuit breaker according to claim 1 , wherein the main circuit breaker includes at least one of a vacuum circuit breaker and a gas circuit breaker.

7. Further comprising an energy absorption unit arranged in parallel with the main circuit breaker. A DC circuit breaker according to any one of claims 1 to 6.

8. The main circuit breaker includes a plurality of circuit breaker units, The circuit breaking unit includes a circuit in which at least one of the vacuum circuit breaker and the gas circuit breaker and an energy absorption unit are connected in parallel with each other. The DC circuit breaker according to claim 6.

9. A main circuit breaker inserted into a DC line; a ladder circuit connected in parallel to the main breaker, The ladder circuit includes two or more vertical wooden members each having three or more branches connected in series; and a horizontal piece interposed between the nodes of the branches of each of the two or more vertical pieces, the nodes being corresponding to each other; A plurality of the branches include a switch; The cross piece includes a storage unit, The main circuit breaker is configured to include at least one of a vacuum circuit breaker or a gas circuit breaker, The main circuit breaker includes a plurality of circuit breaker units, The circuit breaking unit includes a circuit in which at least one of the vacuum circuit breaker and the gas circuit breaker and an energy absorption unit are connected in parallel with each other. DC circuit breaker.

10. A control unit that controls opening and closing of the switch in the DC circuit breaker according to any one of claims 1 to 9, Control device for DC circuit breaker.

11. The control unit controls the switch so as to change at least one of a direction, a frequency, and a magnitude of a current to be superimposed on the current to be interrupted flowing through the main circuit breaker. The control device for a DC circuit breaker according to claim 10.

12. A main circuit breaker inserted in a DC line; a ladder circuit connected in parallel to the main breaker, The ladder circuit includes two or more vertical wooden members each having three or more branches connected in series; and a horizontal piece interposed between the nodes of the branches of each of the two or more vertical pieces, the nodes being corresponding to each other; A plurality of the branches include a switch; The cross piece includes a storage unit. A control unit is provided for controlling opening and closing of the switch in the DC circuit breaker, the control unit controls the switches in a first switching pattern when a current to be interrupted flows through the main circuit breaker in one direction, and after opening all the switches, controls the switches in a second switching pattern; the first opening and closing pattern is a pattern in which, for the plurality of switches included in the first vertical wood section and the second vertical wood section of the two or more vertical wood sections, odd-numbered switches in the first vertical wood section and even-numbered switches in the second vertical wood section are opened, and even-numbered switches in the first vertical wood section and odd-numbered switches in the second vertical wood section are closed; The second opening and closing pattern is a pattern in which, for the multiple switches included in the first vertical wood section and the second vertical wood section of the two or more vertical wood sections, the even-numbered switches in the first vertical wood section and the odd-numbered switches in the second vertical wood section are opened, and the odd-numbered switches in the first vertical wood section and the even-numbered switches in the second vertical wood section are closed. Control device for DC circuit breaker.

13. the control unit controls the switches in the second switching pattern when the current to be interrupted flows through the main circuit breaker in a direction opposite to the one direction, and after opening all of the switches, controls the switches in the first switching pattern. The control device for a direct current circuit breaker according to claim 12.

14. A main circuit breaker inserted in a DC line; a ladder circuit connected in parallel to the main breaker, The ladder circuit includes two or more vertical wooden members each having three or more branches connected in series; and a horizontal piece interposed between the nodes of the branches of each of the two or more vertical pieces, the nodes being corresponding to each other; A plurality of the branches include a switch; The cross piece includes a storage unit. A control unit is provided for controlling opening and closing of the switch in the DC circuit breaker, The control unit adjusts the switch to be closed based on at least one of the magnitude and the direction of the current to be interrupted flowing through the main circuit breaker. Control device for DC circuit breaker.

15. A main circuit breaker inserted in a DC line; a ladder circuit connected in parallel to the main breaker, The ladder circuit includes two or more vertical wooden members each having three or more branches connected in series; A horizontal piece interposed between the nodes of the branches of each of the two or more vertical pieces, the nodes corresponding to each other; A control unit that controls the opening and closing of the switch, A plurality of the branches include the switch, The cross piece includes a storage unit. The computer of the DC circuit breaker control device the control unit controls the switches in a first switching pattern when a current to be interrupted flows through the main circuit breaker in one direction, and after opening all the switches, controls the switches in a second switching pattern; the first opening and closing pattern is a pattern in which, for the plurality of switches included in the first vertical wood section and the second vertical wood section of the two or more vertical wood sections, odd-numbered switches in the first vertical wood section and even-numbered switches in the second vertical wood section are opened, and even-numbered switches in the first vertical wood section and odd-numbered switches in the second vertical wood section are closed; The second opening and closing pattern is a pattern in which, for the multiple switches included in the first vertical wood section and the second vertical wood section of the two or more vertical wood sections, the even-numbered switches in the first vertical wood section and the odd-numbered switches in the second vertical wood section are opened, and the odd-numbered switches in the first vertical wood section and the even-numbered switches in the second vertical wood section are closed. A method for controlling a DC circuit breaker.

16. A main circuit breaker inserted in a DC line; a ladder circuit connected in parallel to the main breaker, The ladder circuit includes two or more vertical wooden members each having three or more branches connected in series; A horizontal piece interposed between the nodes of the branches of each of the two or more vertical pieces, the nodes corresponding to each other; A control unit that controls the opening and closing of the switch, A plurality of the branches include the switch, The cross piece includes a storage unit. The computer of the DC circuit breaker control device the control unit controls the switches in a first switching pattern when a current to be interrupted flows in one direction through the main circuit breaker, and after opening all of the switches, controls the switches in a second switching pattern; the first opening and closing pattern is a pattern in which, for the plurality of switches included in the first vertical wood section and the second vertical wood section of the two or more vertical wood sections, odd-numbered switches in the first vertical wood section and even-numbered switches in the second vertical wood section are opened, and even-numbered switches in the first vertical wood section and odd-numbered switches in the second vertical wood section are closed; The second opening and closing pattern is a pattern in which, for the multiple switches included in the first vertical wood section and the second vertical wood section of the two or more vertical wood sections, the even-numbered switches in the first vertical wood section and the odd-numbered switches in the second vertical wood section are opened, and the odd-numbered switches in the first vertical wood section and the even-numbered switches in the second vertical wood section are closed. program.

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