DC current supply device and DC current supply method

Abstract

To properly control the DC circuit breaker in a DC current supply device. [Solution] The DC current supply device 100 includes first to nth DC circuit breakers 7-K1 to 7-K5, respectively, provided in the paths of the first current output from the DC current source 5 and the second to nth currents branched from the first current, and a measurement control unit 22. The measurement control unit 22 has a function to calculate the time rate of change of the first to nth currents, and when a predetermined fault current generation condition is met for the mth current flowing through the mth DC circuit breaker 7-Km, it determines the closed / open state CL / OP of each of the first to nth DC circuit breakers 7-K1 to 7-K5 based on the time rate of change of the mth current.

Description

[Technical Field]

[0001] The present invention relates to a DC current supply device and a DC current supply method. [Background technology]

[0002] As background technology for this field, the abstract of Patent Document 1 below states: "[Problem] To identify faulty sections in a timely manner using a general-purpose network and eliminate faults with appropriate system shutdown signals. [Solution] A protective relay and a circuit breaker are installed in each of a plurality of substations connected via a circuit. The protective relay generates a logic signal that combines a forward fault detection signal or the operating conditions of the protective element. The protective relay transmits the generated information to a slave station. The slave station transmits the signal transmitted from the protective relay to the slave station, along with the address information and time information of the protective relay, to a calculation unit having a programmable logic controller function via a general-purpose network. The calculation unit determines faults in the circuit connecting the substations based on the logic signal from the protective relay, address information, and time information transmitted from the slave units of each substation." [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2013-90445 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, Patent Document 1 does not specifically describe how to properly control DC circuit breakers in DC systems, etc. This invention has been made in view of the circumstances described above, and aims to provide a DC current supply device and a DC current supply method that can appropriately control a DC circuit breaker. [Means for solving the problem]

[0005] To solve the above problems, the DC current supply device of the present invention comprises a first to nth DC circuit breaker provided in the passage paths of a first current output from a DC current source and second to nth currents branched from the first current, where n is a natural number of 3 or more, and a measurement control unit, wherein the measurement control unit has a function to calculate the time rate of change of the first to nth currents, and where m is a natural number of 2 or more and n or less, when a predetermined fault current generation condition is satisfied for the mth current flowing through the mth DC circuit breaker, it determines the closed and open states of each of the first to nth DC circuit breakers based on the time rate of change of the mth current. [Effects of the Invention]

[0006] According to the present invention, DC circuit breakers can be controlled appropriately. [Brief explanation of the drawing]

[0007] [Figure 1] This is an overall configuration diagram of the DC power supply circuit according to the first embodiment. [Figure 2] This is a block diagram of the measurement and control unit in the first embodiment. [Figure 3] This is a block diagram of a DC circuit breaker control device. [Figure 4] This figure shows an example of the fault current path when a short-circuit fault occurs. [Figure 5] This figure shows an example of a current waveform in the event of a short-circuit fault. [Figure 6] This figure shows an example of direct control in the first embodiment. [Figure 7] This figure shows an example of peripheral control in the first embodiment. [Figure 8] This is a flowchart of the shutdown control routine in the first embodiment. [Figure 9] This is a block diagram of the measurement and control unit in the second embodiment. [Figure 10] This is a block diagram of a computer. [Modes for carrying out the invention]

[0008] [Summary of the Embodiment] In substations, circuit breakers are used to protect the system by interrupting the current when a fault current occurs. For example, in AC current interruption, the current is interrupted at the zero point in each half-cycle of the 50Hz or 60Hz commercial frequency, so the control time of the circuit breaker is several tens of milliseconds. In contrast, with DC current interruption, there is no timing when the current becomes zero when a fault current occurs, so it is necessary to forcibly create a zero point. The rise speed of short-circuit current directly below a substation is, for example, 3 to 10 [kA / ms], so considering the load on the system, it is desirable to perform control in a few milliseconds.

[0009] If these circuit breakers fail to interrupt the current, the cascading effect of the fault could cause widespread power outages. Applying the technology described in Patent Document 1, it is conceivable that protective relays and circuit breakers could be installed in each of the multiple substations connected via a circuit, and that the information generated by the protective relays could be transmitted to the slave stations. Furthermore, it is conceivable that the slave stations could determine faults in the circuits connecting the substations based on the signals transmitted from the protective relays to the slave stations via a general-purpose network using a programmable logic controller function, and based on the logic signals from the protective relays transmitted from the slave units of each substation, as well as address information and time information. However, as mentioned above, Patent Document 1 does not specifically mention DC systems. Therefore, the embodiment described later protects the DC power supply system by protecting DC circuit breakers while suppressing the widespread cascading effect of faults.

[0010] [First Embodiment] <Configuration of the first embodiment> The first embodiment will be described below with reference to the drawings. However, the present invention is not limited to this embodiment. In the drawings, the same parts are denoted by the same reference numerals, where "CL" indicates the closed state and "OP" indicates the open state.

[0011] Figure 1 is an overall configuration diagram of the DC power supply circuit 100 (DC current supply device) according to the first embodiment. In Figure 1, the DC power supply circuit 100 comprises mutually adjacent substations 1-K and 1-L, an upward catenary line 19, and a downward catenary line 20. Substation 1-K comprises an AC circuit breaker 3-K, a transformer 4-K, a rectifier 5-K (DC current source), five DC circuit breakers 7-K1 to 7-K5 (first to nth DC circuit breakers), and a measurement and control unit 22-K (computer).

[0012] Similarly, substation 1-L is equipped with AC circuit breaker 3-L, transformer 4-L, rectifier 5-L, five DC circuit breakers 7-L1 to 7-L5, and measurement control unit 22-L. More generally, when n is a natural number greater than or equal to "3", substations 1-K and 1-L are equipped with DC circuit breakers 7-K1 to 7-Kn and 7-L1 to 7-Ln.

[0013] AC power input to substation 1-K is converted to DC power via transformer 4-K and rectifier 5-K. Similarly, AC power input to substation 1-L is converted to DC power via transformer 4-L and rectifier 5-L. In the following explanation, multiple components, physical quantities, information, etc., having the same or similar function or significance may be represented by adding a hyphen and alphanumeric characters to the same symbol, for example, "DC circuit breaker 7-K1~7-K5". However, if it is not necessary to distinguish between these multiple components, etc., the hyphen and alphanumeric characters may be omitted, for example, "DC circuit breaker 7".

[0014] The upward catenary 19 has electrically conductive sections 19A, 19B, and 19C. Between these sections 19A, 19B, and 19C, there are dead sections (unmarked) that are several meters long and do not conduct electricity. Similarly, the downward catenary 20 has electrically conductive sections 20D, 20E, and 20F. Between these sections 20D, 20E, and 20F, there are dead sections (unmarked).

[0015] During normal operation of the DC power supply circuit 100, all DC circuit breakers 7 in the figure are in the closed state (CL), as shown in Figure 1. DC circuit breakers 7-K1 and 7-L1 are rectifier protection circuit breakers. The DC current output by rectifier 5-K is branched through DC circuit breaker 7-K1 to DC circuit breakers 7-K2, 7-K3, 7-K4, and 7-K5. DC circuit breakers 7-K2, 7-K3, 7-K4, and 7-K5 are then connected to overhead line sections 19A, 20F, 20E, and 19B, respectively.

[0016] Similarly, the DC current output by rectifier 5-L is branched through DC circuit breaker 7-L1 to DC circuit breakers 7-L2, 7-L3, 7-L4, and 7-L5. DC circuit breakers 7-L2, 7-L3, 7-L4, and 7-L5 are then connected to overhead line sections 19B, 20E, 20D, and 19C, respectively.

[0017] Train 120 is equipped with a pantograph 122, and in the state shown in Figure 1, the pantograph 122 is in contact with the overhead line section 19B of the up overhead line 19. As a result, DC current is supplied to train 120 via the DC circuit breaker 7-K5 at substation 1-K, the DC circuit breaker 7-L2 at substation 1-L, and the overhead line section 19B of the up overhead line 19. This DC current returns to substations 1-K and 1-L via the rail 124. The current paths in this case are shown as paths IL25 and IL26 in Figure 1.

[0018] Figure 2 is a block diagram of the measurement control unit 22-K in the first embodiment. In Figure 2, the measurement control unit 22-K includes current measuring instruments 23-K1, 23-K2, 23-K3, 23-K4, and 23-K5, and DC circuit breaker control devices 24-K1, 24-K2, 24-K3, 24-K4, and 24-K5. The current measuring instruments 23-K1 to 23-K5 (the first to nth current measuring instruments) are each inserted into the current output path (the lower path in the figure) of the DC circuit breakers 7-K1 to 7-K5, and the current value I at the insertion point K1 ,I K2 ,I K3 ,I K4 ,I K5 Measure (not shown). These current values ​​I K1 ~IK5 The (first to nth currents) are respectively supplied to the corresponding DC breaker control devices 24-K1 to 24-K5 (first to nth DC breaker control devices). The DC breaker control devices 24-K1 to 24-K5 control the closing / opening states (CL / OP) of the DC breakers 7-K1 to 7-K5 based on the current values I K1 ~I K5 .

[0019] Each DC breaker control device 24 also includes a digital input terminal IN and a digital output terminal OUT. And each DC breaker control device 24 forms a daisy-chain network via the communication cable 27 through the digital input terminal IN and the digital output terminal OUT.

[0020] Each DC breaker control device 24 receives various information output by other DC breaker control devices via the digital input terminal IN, adds its own various information thereto, and outputs it via the digital output terminal OUT. Thus, each DC breaker control device 24 shares various information such as the current values I K1 ~I K5 etc.

[0021] It is preferable to apply EtherCAT (registered trademark) etc. which can respond quickly without intervening software for the communication protocol between the DC breaker control devices 24. Also, when adopting a communication protocol with intervening software, it is preferable to adopt a communication protocol that can respond quickly.

[0022] Also, although not shown in the figure, the measurement control unit 22-L (see FIG. 1) in the substation 1-L is also configured in the same way as the measurement control unit 22-K. That is, the measurement control unit 22-L includes current measuring devices 23-L1 to 23-L5 and DC breaker control devices 24-L1 to 24-L5 which are configured in the same way as the current measuring devices 23-K1 to 23-K5 and the DC breaker control devices 24-K1 to 24-K5.

[0023] Figure 3 is a block diagram of the DC circuit breaker control device 24-K1. However, other DC circuit breaker control devices 24 are configured similarly. In Figure 3, the DC circuit breaker control device 24-K1 includes an input / output unit 30, a control unit 31, and a communication port 32. Here, the control unit 31 is connected to the input / output unit 30 and the communication port 32. The input / output unit 30 includes A / D converters 302, 308, a digital input unit 304, and a digital output unit 306.

[0024] The A / D converter 308 receives the analog current value I output by the current measuring instrument 23-K1. K1 The values ​​are converted into digital values ​​and supplied to the control unit 31. The digital output unit 306 also outputs an operation command CM-K1 that commands the closed / open state (CL / OP) based on the command from the control unit 31.

[0025] Furthermore, the A / D converter 302 and the digital input unit 304 acquire status information ST-K1 of the DC circuit breaker 7-K1 and supply it to the control unit 31. Status information ST-K1 is a signal indicating the state of the circuit breaking performance of the DC circuit breaker 7-K1. For example, if the DC circuit breaker 7-K1 is a DC high-speed air circuit breaker, its status information ST-K1 is information such as the surface roughness of the electrodes and the specifications of the operating mechanism. Also, if the DC circuit breaker 7-K1 is, for example, a DC high-speed vacuum circuit breaker, its status information ST-K1 is information such as the capacitor capacity and voltage used in the reverse current injection method.

[0026] The control unit 31 of the DC circuit breaker control device 24-K1 receives the status information ST-K1 and the current value I K1 Based on the time-series information, the current value I at the current time K1 Time rate of change dI K1 Calculate / dt and determine the current value I during the predetermined prediction period. K1 and the rate of change over time dI K1The prediction of the transition of / dt is calculated. Here, the prediction period is, for example, the period from the current time to a time 100 [ms] in the future. Then, the control unit 31 of the DC circuit breaker control device 24-K1 notifies the other DC circuit breaker control devices 24-K2 to 24-K5 of these calculation results by outputting them from the digital input terminal OUT of the communication port 32.

[0027] Other DC circuit breaker control devices 24-K2 to 24-K5 operate in the same way as DC circuit breaker control device 24-K1. Therefore, the DC circuit breaker control devices 24-K1 to 24-K5 shown in Figure 3 operate with a current value I K1 ~I K5 And these time rates of change dI K1 / dt~dI K5 / dt and the current value I during the prediction period K1 ~I K5 Prediction of trends and the time change rate dI during the forecast period K1 / dt~dI K5 The system shares the predicted transition of / dt, status information ST-K1 to ST-K5, and operation commands CM-K1 to CM-K5 in real time.

[0028] Figure 4 shows an example of the fault current path when a short-circuit fault occurs. Specifically, in Figure 4, it is assumed that a short-circuit point 33 occurs where the resistance value between the overhead wire section 19B of the upward overhead wire 19 and the rail 124 becomes "0". There are five possible paths through which current can flow into the short-circuit point 33. • Route IL34: A route from overhead line section 19A to short-circuit point 33 via DC circuit breakers 7-K2 and 7-K5. • Route IL35: A route from overhead line section 20F to short-circuit point 33 via DC circuit breakers 7-K3 and 7-K5. • Route IL36: A route that reaches short-circuit point 33 via rectifier 5-K, DC circuit breaker 7-K1, and DC circuit breaker 7-K5 at substation 1-K. • Route IL37: A route that reaches short-circuit point 33 via rectifier 5-L, DC circuit breaker 7-L1, and DC circuit breaker 7-L2 of substation 1-L. Route IL38: A route that reaches short-circuit point 33 via rectifier 5-L, DC circuit breaker 7-L1, DC circuit breaker 7-L3, overhead line section 20E, and DC circuit breakers 7-K4 and 7-K5 of substation 1-L.

[0029] The closer the short-circuit point 33 is to substation 1-K, the higher the current value I in DC circuit breakers 7-K1 and 7-K5. K1 ,I K5 The current increases. In particular, the DC circuit breaker 7-K5 receives current from the surrounding overhead line sections, so its current value increases. Figure 4 shows the case where a short-circuit fault occurs in overhead line section 20E, but for example, short-circuit faults may also occur in overhead line sections 19A and 20F at the same time as overhead line section 20E. In this way, when short-circuit faults occur in multiple locations, the current flowing through the DC circuit breakers 7 involved increases.

[0030] Figure 5 shows an example of a current waveform in the event of a short-circuit fault. The horizontal axis represents time t, and the vertical axis represents the current value I. This current value I is the result of measurement by one of the current measuring instruments 23 (see Figure 2). Assume that a short-circuit fault occurs at fault occurrence time t0. The current value I before fault occurrence time t0 is a relatively low value and is almost constant. However, at fault occurrence time t0, the current value I rises sharply. That is, the rate of change of the current value I, dI / dt, increases rapidly. The rate of change of the current value, dI / dt, at fault occurrence time t0 is a value governed by the impedance of the upstream overhead line 19 and the downstream overhead line 20, and the rate of change of the current value, dI / dt, increases as the short-circuit point 33 approaches either substation 1-K or 1-L.

[0031] Although not shown in the diagram, the DC circuit breaker 7 has an electromagnet and a mechanical contact driven by this electromagnet. Even if current is immediately supplied to the electromagnet at the time of fault occurrence t0, it takes several tens of milliseconds for the mechanical contact to actually begin to separate. The time when this mechanical contact begins to separate is the time of interruption start t1 (expected time of interruption start). Even if the mechanical contact begins to separate at the time of interruption start t1, an arc discharge occurs in the DC circuit breaker 7, so the current value I does not immediately become "0", but is attenuated at a certain rate. Then, in the example shown in the diagram, at the time of interruption completion t2, the interruption operation is completed and the current value I becomes "0".

[0032] Therefore, in the series of changes in current value I, the current value I at the interruption start time t1 is called the cutoff value Ic. The dashed curve shows the current value I assuming that the corresponding DC circuit breaker 7 did not perform an interruption operation. Each DC circuit breaker 7 has a rating for the current it can interrupt according to its interruption capacity, and that rating is called the rated cutoff current I. N This is called the cutoff value Ic, which is the rated cutoff current I. N It must be less than or equal to the following. Conversely, the cutoff value Ic is equal to the rated cutoff current I N If the value exceeds this limit, the DC circuit breaker 7 must not be left open (OP).

[0033] Here, the rated cutoff current of the DC circuit breaker 7-K1 is I N1 This is called the rated cutoff current of DC circuit breakers 7-K2 to 7-K5, and I N2 It is called that. And the rated cutoff current I N1 ,I N2 is, "I N1 >I N2 The relationship is as follows: DC circuit breaker 7-K1 can interrupt a larger current than DC circuit breakers 7-K2 to 7-K5.

[0034] However, in this embodiment, whether or not the DC circuit breaker 7-K1 can be opened (OP) depends on the threshold current I th1Using this value, whether or not DC circuit breakers 7-K2 to 7-K5 can be opened (OP) depends on the threshold current I th2 The value used is the threshold current I. th1 ,I th2 The rated cutoff current I N1 ,I N2 The same value is also acceptable, but in order to ensure a margin, the rated cutoff current I N1 ,I N2 It is best to set the specified value slightly lower than the specified value. Also, since the specifications of DC circuit breakers 7-K2 to 7-K5 may differ depending on the application, the threshold current I of DC circuit breakers 7-K2 to 7-K5 should be set accordingly. th2 This can be set to a different value.

[0035] Figure 6 shows an example of direct control in the first embodiment. Here, direct control is a control method in which, when a fault current occurs in a certain DC circuit breaker 7-Km (where 2≦m≦5), the DC circuit breaker 7-Km is opened (OP), and the DC circuit breakers 7-K1 to 7-K5, excluding DC circuit breaker 7-Km, are kept closed (CL). Direct control is performed when the cutoff value Ic (see Figure 5) flowing through the DC circuit breaker 7-Km is the threshold current I th2 It will be adopted if the following is predicted:

[0036] In Figure 6, the cutoff value Ic of the fault current flowing through the DC circuit breaker 7-K5 is the threshold current I th2 The following describes the direct control process when the following is predicted. In this case, as shown in the figure, the DC circuit breaker control device 24 keeps DC circuit breakers 7-K1 to 7-K4 in the closed state (CL), and opens only DC circuit breaker 7-K5 in the open state (OP) within substation 1-K. This allows the current flowing from overhead line sections 19A, 20E, 20F and rectifier 5-K into overhead line section 19B to be interrupted.

[0037] Furthermore, it is preferable to provide a function that allows the DC circuit breaker control devices 24 in substations 1-K and 1-L to communicate with each other, thereby notifying the other side of which DC circuit breakers 7 should be set to the open state (OP). As a result, in the illustrated example, at substation 1-L, DC circuit breakers 7-L2 and 7-L3 ​​are set to the open state (OP), while the other DC circuit breakers 7-L1, 7-L4, and 7-L5 remain in the closed state (CL).

[0038] Figure 7 shows an example of peripheral control in the first embodiment. Here, peripheral control refers to the control that, when a fault current occurs in a certain DC circuit breaker 7-Km (where 2≦m≦5), keeps that DC circuit breaker 7-Km in the closed state (CL) and opens at least DC circuit breaker 7-K1 (OP). Furthermore, in peripheral control, if there is a possibility that current may flow back from DC circuit breakers 7-K2~7-K5 to DC circuit breaker 7-Km, the DC circuit breakers 7-K2~7-K5, excluding DC circuit breaker 7-Km, are opened (OP). Peripheral control is performed when the cutoff value Ic (see Figure 5) flowing through DC circuit breaker 7-Km is the threshold current I th2 It is adopted when it is predicted to exceed [a certain value].

[0039] In Figure 7, the cutoff value Ic of the fault current flowing through the DC circuit breaker 7-K5 is the threshold current I th2 This shows the peripheral control measures taken when the threshold current is predicted to exceed a certain value. Specifically, Figure 7 shows that the cutoff value Ic (see Figure 5) of the fault current flowing through the DC circuit breaker 7-K5 is exceeded by the threshold current I th2 This shows the opening operation when it is predicted that the current will exceed a certain threshold. For example, this can happen if a short circuit occurs in overhead line sections 19A, 20F, etc., simultaneously with overhead line section 20E. The cutoff value Ic of the fault current (see Figure 5) is equal to the threshold current I. th2 If the DC circuit breaker 7-K5 is opened when the current exceeds a certain value, it may be damaged. Therefore, in this case, the DC circuit breaker control device 24 keeps DC circuit breaker 7-K5 closed (CL) and opens DC circuit breakers 7-K1 to 7-K4 (OP). In other words, when the cutoff value Ic exceeds the threshold current I th2If the value exceeds this limit, the first DC circuit breaker (DC circuit breaker 7-K1) is opened while the mth DC circuit breaker (in this case, DC circuit breaker 7-K5) is kept closed.

[0040] This allows the current flowing from overhead line sections 19A, 20E, 20F and rectifier 5-K to overhead line section 19B to be interrupted. Furthermore, as described above, it is desirable to provide a function that allows the DC circuit breaker control devices 24 in substations 1-K and 1-L to communicate with each other, thereby notifying the other side of which DC circuit breakers 7 should be set to the open state (OP). As a result, in the illustrated example, in substation 1-L, DC circuit breakers 7-L2 and 7-L3 ​​are set to the open state (OP), while the other DC circuit breakers 7-L1, 7-L4, and 7-L5 remain in the closed state (CL).

[0041] Figure 8 is a flowchart of the tripping control routine in the first embodiment. This routine is executed in parallel in all DC circuit breaker control devices 24, but here we will explain it as an example of the routine executed in DC circuit breaker control device 24-K1. In Figure 8, when the process proceeds to step S2, the DC circuit breaker control device 24 performs data acquisition and data sharing processing. First, the DC circuit breaker control device 24 acquires the current value from the current measuring instrument 23 connected to itself, and also acquires status information ST from the DC circuit breaker 7 connected to itself. As shown in Figure 3, in the case of the DC circuit breaker control device 24-K1, the current value I K1 The system acquires the data and obtains the status information ST-K1 from the DC circuit breaker 7-K1.

[0042] Next, the DC circuit breaker control device 24 shares this data with other DC circuit breaker control devices 24. Therefore, the DC circuit breaker control devices 24-K1 to 24-K5 shown in Figure 2 share the current value I K1 ~I K5 , these time rates of change dI K1 / dt~dI K5 / dt, status information ST-K1~ST-K5, operation commands CM-K1~CM-K5, etc. are shared in real time.

[0043] Next, when the process proceeds to step S4, each DC circuit breaker control device 24 determines whether a predetermined fault current generation condition has been met in any of the DC circuit breakers 7-K2 to 7-K5. Here, the fault current is, for example, a short-circuit current. For example, the time rate of change dI of DC circuit breaker 7-Km (where 2 ≤ m ≤ 5) Km When / dt exceeds a predetermined value, it can be determined that the predetermined fault current generation conditions for the DC circuit breaker 7-Km have been met.

[0044] If "No" is determined in step S4, the process returns to step S2, and the loop of steps S2 and S4 is repeated until a fault current occurs in any of the DC circuit breakers 7-K2 to 7-K5. On the other hand, if "Yes" is determined in step S4, the process proceeds to step S6. In step S6, the DC circuit breaker control device 24 estimates the cutoff value Ic (see Figure 5) for the fault current, and this estimated cutoff value Ic is the threshold current I th2 Determine whether or not the following applies.

[0045] If "Yes" is determined in step S6, the process proceeds to step S8, and the DC circuit breaker control device 24 performs the direct control illustrated in Figure 6. That is, the DC circuit breaker control device 24-Km that controls the DC circuit breaker 7-Km where a fault current has been detected sets the DC circuit breaker 7-Km to the open state (OP). Meanwhile, the other DC circuit breaker control devices 24 maintain the corresponding DC circuit breakers 7 in the closed state (CL). In the example shown in Figure 6, the DC circuit breaker control device 24-K5 (see Figure 2) sets the DC circuit breaker 7-K5 to the open state (OP), and the other DC circuit breaker control devices 24-K1 to 24-K4 maintain the DC circuit breakers 7-K1 to 7-K4 in the closed state (CL).

[0046] On the other hand, if "No" is determined in step S6, the process proceeds to step S10, and the DC circuit breaker control device 24 performs the peripheral control illustrated in Figure 7. That is, the DC circuit breaker control device 24-Km that controls the DC circuit breaker 7-Km in which a fault current has been detected maintains the DC circuit breaker 7-Km in the closed state (CL). Meanwhile, the other DC circuit breaker control devices 24 set the corresponding DC circuit breaker 7 in the open state (OP). In the example shown in Figure 7, the DC circuit breaker control device 24-K5 (see Figure 2) maintains the DC circuit breaker 7-K5 in the closed state (CL), and the other DC circuit breaker control devices 24-K1 to 24-K4 set the DC circuit breakers 7-K1 to 7-K4 in the open state (OP).

[0047] As described above, according to the first embodiment, the measurement control unit 22 determines that the cutoff value Ic is the threshold current I th2 Direct control or peripheral control is selected based on whether or not it exceeds the threshold current Ic. If the specifications of DC circuit breakers 7-K2 to 7-K5 were determined based on the maximum value of the assumed cutoff value Ic, the DC circuit breakers 7-K2 to 7-K5 would become larger and more expensive. In this embodiment, the cutoff value Ic is the threshold current Ic. th2 When the threshold current I exceeds a certain value, peripheral control can be selected, so th2 This allows for a relatively low value to be used. As a result, smaller and less expensive DC circuit breakers 7-K2 to 7-K5 can be applied.

[0048] [Second Embodiment] Next, a DC power supply circuit according to the second embodiment will be described. In the description of the second embodiment, parts corresponding to parts of the first embodiment will be denoted by the same reference numerals, and their descriptions may be omitted. The configuration of the DC power supply circuit according to the second embodiment differs from that of the DC power supply circuit 100 according to the first embodiment (see Figures 1 to 3) in the configuration of the measurement control units 22-K and 22-L. The configuration other than that of the measurement control units 22-K and 22-L is the same as that of the first embodiment.

[0049] Figure 9 is a block diagram of the measurement control unit 22-K in the second embodiment. In Figure 9, the measurement control unit 22-K comprises current measuring instruments 23-K1, 23-K2, 23-K3, 23-K4, and 23-K5, DC circuit breaker control devices 24-K1, 24-K2, 24-K3, 24-K4, and 24-K5, and a master control unit 28-K. Each DC circuit breaker control device 24 is connected to the master control unit 28-K, thereby forming a star-shaped network centered on the master control unit 28-K. The current measuring instruments 23-K1 to 23-K5 measure current values ​​I, similar to those in the first embodiment (see Figure 2). K1 ~I K5 (Not shown) is measured, and the measurement results are supplied to the corresponding DC circuit breaker control devices 24-K1 to 24-K5.

[0050] In this embodiment, the DC circuit breaker control devices 24-K1 to 24-K5 have a current value I K1 ~I K5 The system supplies status information ST-K1~ST-K5 and current operation commands CM-K1~CM-K5 to the master control unit 28-K, and outputs operation commands CM-K1~CM-K5 to the corresponding DC circuit breakers 7-K1~7-K5 based on the commands from the master control unit 28-K. The master control unit 28-K outputs current value I K1 ~I K5 Based on these time rates of change dI K1 / dt~dI K5 / dt and the current value I during the prediction period K1 ~I K5 Prediction of trends and the time change rate dI during the forecast period K1 / dt~dI K5 The master control unit 28-K then calculates the predicted transition of / dt and other parameters. Based on these calculation results, it determines whether or not a fault current has occurred in any of the DC circuit breakers 7-K2 to 7-K5.

[0051] Furthermore, if the master control unit 28-K determines that a fault current has occurred, it estimates a cutoff value Ic (see Figure 5) for that fault current, and this estimated cutoff value Ic is the threshold current I th2The system determines whether the following conditions are met. Based on this determination, the master control unit 28-K decides whether to perform direct control (see Figure 6) or peripheral control (see Figure 7), and based on the decision, commands each DC circuit breaker control device 24 to set the closed / open state (CL / OP) of the corresponding DC circuit breaker 7. The measurement control unit 22-L (see Figure 1) located in substation 1-L is configured similarly to the measurement control unit 22-K described above.

[0052] As described above, according to the second embodiment, the measurement control unit 22, similar to that of the first embodiment, sets the cutoff value Ic to the threshold current I th2 Based on whether or not it exceeds a certain limit, direct control or peripheral control can be selected. Furthermore, in this embodiment, since a star-type network is adopted, a decrease in communication speed can be suppressed even when there are many DC circuit breaker control devices 24.

[0053] [Computer Configuration] Figure 10 is a block diagram of the computer 980. The control unit 31 shown in Figure 3 and the master control unit 28-K shown in Figure 9 both consist of one or more computers 980 as shown in Figure 10. In Figure 10, the computer 980 comprises a CPU 981, a memory unit 982, a communication interface 983, an input / output interface 984, and a media interface 985. Here, the memory unit 982 comprises a RAM 982a, a ROM 982b, and an SSD (Solid State Drive) 982c.

[0054] The communication interface 983 is connected to the communication circuit 986. The input / output interface 984 is connected to the input / output device 987. The media interface 985 reads and writes data to the recording medium 988. The ROM 982b stores the IPL (Initial Program Loader) and other programs executed by the CPU. The SSD 982c stores control programs and various data. The CPU 981 executes the shutdown control routine (Figure 8) and other programs by executing the control programs and other programs read from the SSD 982c into the RAM 982a.

[0055] [Differentiation] The present invention is not limited to the embodiments described above, and various modifications are possible. The embodiments described above are illustrative examples provided to facilitate understanding of the present invention, and are not necessarily limited to those comprising all the described configurations. Furthermore, it is possible to replace parts of the configuration of one embodiment with those of another embodiment, and to add configurations from other embodiments to the configuration of one embodiment. It is also possible to delete parts of the configuration of each embodiment, or to add or replace other configurations. In addition, the control lines and information lines shown in the figures are those considered necessary for explanation, and do not necessarily represent all control lines and information lines required in the product. In practice, it can be assumed that almost all configurations are interconnected. Possible modifications to the above embodiments are as follows, for example.

[0056] (1) Since the hardware of the control unit 31 and the master control unit 28 in the above embodiment can be implemented by a general-purpose computer, programs that perform the processes corresponding to the flowchart described above and other various processes described above may be stored in a storage medium (a computer-readable recording medium on which the program is recorded) or distributed via a transmission line.

[0057] (2) Although the processes corresponding to the flowchart described above, and other various processes described above, were described as software processes using a program in the above embodiment, some or all of them may be replaced with hardware processes using an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array), etc.

[0058] [Effects of the Embodiment] As described above, according to the embodiment described above, the DC current supply device (100) sets n to a natural number of 3 or more, and the first current (I) output from the DC current source (5) K1 ) and the first current (IK1 ) the second to nth branched currents (I K2 ~I K5 ), respectively provided in the passing paths of the first to nth DC circuit breakers (7-K1 to 7-K5), and a measurement control unit 22. The measurement control unit 22 calculates the time change rates (dI K1 ~I K5 / dt~dI K1 / dt) of the first to nth currents (I K5 ~I Km ). When m is a natural number from 2 to n, and a predetermined fault current generation condition is satisfied for the mth current (I Km ) flowing through the mth DC circuit breaker (7-Km), based on the time change rate (dI Km / dt) of the mth current (I Km ), the closing / opening states (CL / OP) of each of the first to nth DC circuit breakers (7-K1 to 7-K5) are determined. Thus, since the closing / opening states (CL / OP) of each of the first to nth DC circuit breakers (7-K1 to 7-K5) can be determined based on the time change rate (dI Km / dt) of the mth current (I

[0059] ), the DC circuit breakers can be appropriately controlled. Km ), and when the cut-off value Ic, which is the estimated value of the third current (I th2 ) when it is assumed that the mth DC circuit breaker (7-Km) is in the open state (OP) at the predicted cut-off start time (t1) in the future, is less than or equal to a predetermined threshold current I th2 (a predetermined value slightly lower than the rated cut-off current I N2 ), it is more preferable to set the mth DC circuit breaker (7-Km) to the open state (OP) while maintaining the first DC circuit breaker (7-K1) in the closed state (CL). Thus, when the cut-off value (Ic) is less than or equal to the predetermined threshold current I Km ), the mth DC circuit breaker (7-Km) can cut off the mth current (I

[0060] ). Further, the measurement control unit 22 determines that when the cut-off value Ic is greater than the threshold current I th2When it exceeds, it is more preferable to set the first DC breaker (7-K1) to the open state (OP) while maintaining the m-th DC breaker (7-Km) in the on state (CL). Thereby, when the cut-off value (Ic) exceeds the threshold current I th2 When it exceeds, the first DC breaker (7-K1) can cut off the current flowing from the DC current source 5 to the m-th DC breaker (7-Km).

[0061] Also, when the cut-off value Ic exceeds the threshold current I th2 When it exceeds, it is more preferable to further set, among the second to n-th DC breakers (7-K2 to 7-K5), those other than the m-th DC breaker (7-Km) to the open state (OP). Thereby, the current flowing around from the DC breakers other than the m-th DC breaker (7-Km) to the m-th DC breaker (7-Km) can also be cut off.

[0062] Also, the DC current source (5) converts the AC current supplied via the transformer 4 into a DC current, and the second to n-th currents (I K2 ~I K5 ) are respectively supplied to the corresponding overhead line sections 19A, 19B, 19C, 20D, 20E, 20F. The measurement control unit 22 includes first to n-th ammeters (23-K1 to 23-K5) that output the measurement results of the first to n-th currents (I K1 ~I K5 ), and first to n-th DC breaker control devices (24-K1 to 24-K5) that respectively control the opening and closing states of the first to n-th DC breakers (7-K1 to 7-K5). The first to n-th DC breaker control devices (24-K1 to 24-K5) receive the first to n-th currents (I K1 ~I K5It is even more preferable to receive the measurement results of each of the DC circuit breakers (7-K1 to 7-K5) and share the received measurement results and the open / closed states of the first to nth DC circuit breakers (7-K1 to 7-K5) with the other DC circuit breaker control devices (24-K1 to 24-K5) by communication. This allows the processing that should be performed by the measurement control unit 22 to be distributed among multiple DC circuit breaker control devices (24-K1 to 24-K5).

[0063] Furthermore, the first to nth DC circuit breaker control devices (24-K1 to 24-K5) also control the time rate of change (dI) of each of the first to nth currents. K1 / dt~dI K5 The current of the mth DC circuit breaker (I) when the mth DC circuit breaker (7-Km) is assumed to be open (OP) at the predicted future interruption start time (t1). Km It is even more preferable to share the cutoff value Ic, which is an estimated value of ), with the other parameters. This allows multiple DC circuit breaker control devices to operate in a unified manner based on the shared cutoff value Ic. [Explanation of Symbols]

[0064] 4. Transformer 5 Rectifier (DC current source) 7-K1~7-K5 DC circuit breakers (1st to nth DC circuit breakers) 19A, 19B, 19C, 20D, 20E, 20F Overhead line section 22 Measurement Control Unit (Computer) 23-K1~23-K5 Current measuring instruments (1st to nth current measuring instruments) 24-K1~24-K5 DC Circuit Breaker Control Device (1st to nth DC Circuit Breaker Control Device) 100 DC power supply circuit (DC current supply device) Ic cutoff value t1 Interruption start time (estimated interruption start time) I K1 ~I K5 Current value (1st to nth current) I th2 Threshold current

Claims

1. Let n be a natural number of 3 or more, and first to n DC circuit breakers are provided in the paths of the first current output from the DC current source and the second to nth currents branched from the first current, It comprises a measurement control unit and, The measurement control unit, A function for calculating the time rate of change of the first to nth currents, Let m be a natural number between 2 and n. When a predetermined fault current generation condition is met for the m-th current flowing through the m-th DC circuit breaker, the closed and open states of the first to n DC circuit breakers are determined based on the time rate of change of the current m. A DC current supply device characterized by the following features.

2. The measurement control unit, If the cutoff value, which is an estimated value of the current of the DC circuit breaker m assuming that the DC circuit breaker m is in the open state at the predicted future interruption start time, is less than or equal to a predetermined threshold current, the DC circuit breaker m is opened while the first DC circuit breaker is kept in the closed state. The DC current supply device according to feature 1.

3. The measurement and control unit, when the cutoff value exceeds the threshold current, maintains the m DC circuit breaker in the closed state while opening the first DC circuit breaker. The DC current supply device according to feature 2.

4. The measurement and control unit, when the cutoff value exceeds the threshold current, further opens the second to nth DC circuit breakers, excluding the mth DC circuit breaker. The DC current supply device according to feature 3.

5. The aforementioned DC current source converts alternating current supplied via a transformer into direct current. The second to nth currents are supplied to the corresponding overhead line sections, The measurement control unit, Each of the first to n current measuring instruments outputs the measurement result of the first to n currents, Each comprises a first to n DC circuit breaker control device that controls the open / closed state of the first to n DC circuit breakers, The first to nth DC circuit breaker control devices each receive the measurement results of the first to nth currents from the corresponding first to nth current measuring instruments, and share the received measurement results and the open / closed states of the first to nth DC circuit breakers with other DC circuit breaker control devices by communication. The DC current supply device according to feature 1.

6. The first to nth DC circuit breaker control devices further include: The time rate of change of each of the first to nth currents, The cutoff value, which is an estimated value of the current m when the DC circuit breaker m is assumed to be in an open state at the predicted future interruption start time, is shared with The DC current supply device according to feature 5.

7. A DC current supply method performed in a computer that controls a first DC circuit breaker provided in the path of a first current output from a DC current source and a second to nth current branched from the first current, wherein n is a natural number of 3 or more, The process for calculating the time rate of change of the first to nth currents, The process includes determining the closed / open state of each of the first to n DC circuit breakers based on the time rate of change of the current m, when a predetermined fault current generation condition is met for the current m flowing through the m DC circuit breaker, where m is a natural number between 2 and n. A method for supplying direct current, characterized by the following features.

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