Capacitor capacitance determination device, capacitor capacitance determination method, and program

Abstract

A capacitor capacitance determination device according to the present invention for determining the capacitance of a coordination capacitor which is used in a DC power supply system comprises a calculation unit that uses the impedance of wiring connected to a circuit breaker and the rated voltage of the DC power supply system to calculate the amount of charge discharged from the coordination capacitor from the time at which the coordination capacitor starts discharging to the time at which the magnitude of the current flowing through the circuit breaker reaches the current interruption threshold of the circuit breaker, and calculates the capacitance from the amount of charge and the rated voltage.

Description

Capacitor capacitance determination device, capacitor capacitance determination method, and program 【0001】 This invention relates to protection coordination technology in DC power supply systems. 【0002】 A conventional technique for protective coordination involves combining a circuit breaker with a capacitor (referred to as a coordination capacitor) to achieve protective coordination (Non-Patent Literature 1). This technique allows the current flowing from the coordination capacitor to open only the circuit breaker closest to the fault point when a fault such as a short circuit occurs. 【0003】 WO2024105742 【0004】 Verification of Short-Circuit Protection Methods in Loop Wiring Outdoor DC Power Supply Systems (2024 IEICE Society Conference Second-Order Circuits - Study Guides | CircuitBread, https: / / www.circuitbread.com / study-guides / dc-circuits / second-order-circuits) 【0005】 As described above, protective coordination is possible with a coordinating capacitor, but if the capacitance of the coordinating capacitor is too small, protective coordination may not be possible. Conversely, if the capacitance is too large, equipment costs will increase. Therefore, it is necessary to select an appropriate capacitance. Conventional technology does not have a method for appropriately determining the capacitance of the coordinating capacitor necessary for protective coordination. 【0006】 This invention has been made in view of the above points, and aims to provide a technique for appropriately determining the capacitance of a coordinating capacitor for protective coordination. 【0007】According to the disclosed technology, a capacitor capacitance determination device is provided for determining the capacitance of a coordinating capacitor used in a DC power supply system, comprising a calculation unit that uses the impedance of the wiring connected to a circuit breaker and the rated voltage of the DC power supply system to calculate the amount of charge discharged from the coordinating capacitor from the discharge start time of the circuit breaker until the time when the magnitude of the current flowing through the circuit breaker reaches the current interruption threshold of the circuit breaker, and calculates the capacitance from the amount of charge and the rated voltage. 【0008】 The disclosed technology provides a technique for appropriately determining the capacitance of the coordinating capacitor for protective coordination. 【0009】 This is a diagram illustrating a conventional technology for protection coordination using a coordinating capacitor. This is a diagram illustrating an example of the configuration of a bus-type DC grid. This is a diagram illustrating an example of the configuration of a loop-type DC grid. This is a diagram illustrating an example of the configuration of a capacitor capacitance determination device 200 in an embodiment of the present invention. This is a diagram illustrating an example of the configuration of a three-way SCCB 100. This is a diagram illustrating an example of the configuration of a three-way SCCB 100. This is a diagram illustrating a method for calculating the amount of charge. This is a flowchart of operation example 1 of the capacitor capacitance determination device 200. This is a flowchart of operation example 2 of the capacitor capacitance determination device 200. This is a diagram illustrating an embodiment. This is a diagram illustrating an example of the hardware configuration of the device. 【0010】 Hereinafter, embodiments of the present invention (this embodiment) will be described with reference to the drawings. The embodiments described below are merely examples, and the embodiments to which the present invention is applied are not limited to the embodiments described below. 【0011】 The following will first describe the conventional technology and its problems in more detail, and then describe the technology according to this embodiment. 【0012】 In this embodiment, a semiconductor circuit breaker is used as the circuit breaker, but the technology according to the present invention is also applicable to circuit breakers other than semiconductor circuit breakers. 【0013】(Regarding prior art) As mentioned above, prior art includes a technique for achieving protective coordination by combining a semiconductor circuit breaker (hereinafter referred to as SCCB) and a coordinating capacitor (for example, Non-Patent Document 1). 【0014】 The above-mentioned prior art will be described with reference to Figure 1. Figure 1 shows two three-way SCCBs 100A and 100B that constitute a part of a DC power supply system (DC grid). Each three-way SCCB 100 is installed at the intersection (branching point) of the main line and branch line of the DC power supply system. As shown in Figure 1, the three-way SCCB 100A includes SCCBs 1 to 3 and a coordinating capacitor 10. The three-way SCCB 100B has a similar configuration. 【0015】 The DC grid on which the three-way SCCB100 is installed may be either a bus type or a loop type. Figure 2 shows an example of a bus type DC grid configuration, and Figure 3 shows an example of a loop type DC grid configuration. 【0016】 If the main line tripping thresholds are equal, when a fault such as a short circuit occurs, the current flowing from the coordinating capacitor 10 will trip (turn OFF, open) only the SCCB closest to the fault point, minimizing the impact of the fault. This allows power supply to the DC power supply system to continue except at the fault point. 【0017】 In the example shown in Figure 1, a short circuit occurs on the left side of the three-way SCCB 100A. In this case, the discharge current of the coordinating capacitor 10 opens the SCCB 1 closest to the short circuit point. 【0018】 (Regarding the problem) In this way, protective coordination becomes possible with the coordination capacitor 10, but the capacitance C of the coordination capacitor 10 ｃ If the capacity C is too small, protective coordination may not be possible. ｃ If it is too large, equipment costs will increase. Therefore, an appropriate capacity C ｃ It is necessary to select one. 【0019】However, in the prior art, there is no method for determining the capacitance of the cooperation capacitor 10 which is the minimum required for protection cooperation. Therefore, at present, when verifying by incorporating the cooperation capacitor 10 into an actual DC power supply system or by incorporating the cooperation capacitor 10 into an experimental system simulating the DC power supply system, the capacitance C of the cooperation capacitor 10 ｃ is determined. 【0020】 As described above, it takes a huge amount of cost and time to verify by incorporating the cooperation capacitor 10 into an actual DC power supply system or by incorporating the cooperation capacitor 10 into an experimental system simulating the DC power supply system. In addition, due to the land, terrain, power capacity, arrangement, etc. of the building for constructing the DC power supply system, it is necessary to design various DC power supply systems, and each time it takes cost and time. 【0021】 When using a circuit simulator that has been conventionally used, it is necessary to input a huge number of circuit elements and parameters for each system to be designed, and time is required for creating a circuit model. In addition, since it is necessary to construct an experimental system for verifying the validity of the circuit model for each system to be designed, it takes even more time. 【0022】 (Outline of the Embodiment) Therefore, in the technology according to this embodiment, without verifying by incorporating the cooperation capacitor 10 into an actual DC power supply system or by incorporating the cooperation capacitor 10 into an experimental system simulating the DC power supply system, a capacitor capacitance determination device 200 described later determines the capacitance C of the cooperation capacitor 10 ｃ is determined. 【0023】 The capacitor capacitance determination device 200 can calculate the capacitance of the cooperation capacitor with the minimum necessary input variables and in a short time. 【0024】 (Configuration of the Capacitor Capacitance Determination Device 200) FIG. 4 shows a configuration example of the capacitor capacitance determination device 200 in this embodiment. The capacitor capacitance determination device 200 determines the capacitance C of the cooperation capacitor 10 in a plurality of directions SCCB from the design information of the DC power supply system ｃ is determined. 【0025】 As shown in FIG. 1, the capacitor capacitance determination device 200 includes an information acquisition unit 210, a data storage unit 220, a selection unit 230, a calculation unit 240, and an output unit 250. Further, outside the capacitor capacitance determination device 200, a DB (database) 300 for holding input data is provided. 【0026】 For example, the following design information (1) to (5) is input to the information acquisition unit 210 as input data. 【0027】 (1) Number of directions of the multi-direction SCCB: n (n = 1, 2, 3,...) (2) Impedance of the wiring connected to the multi-direction SCCB (e.g., a value obtained from the cross-sectional area and length of the wiring) For example, a numerical value converted from the cross-sectional area and length of the wiring into a value in units of Ω or a value in units of H is used for calculation. 【0028】 (3) Current interruption threshold for each direction of the multi-direction SCCB (4) Rated voltage of the DC power supply system (5) Correction coefficient and margin coefficient (each being 1 or more) The correction coefficient is a value obtained experimentally or from empirical rules and is used for the purpose of filling the difference between the calculation result and the measured value. The margin coefficient is a coefficient indicating the margin given to the capacitor capacitance in consideration of manufacturing errors of the capacitor and SCCB. 【0029】 The operation outlines of each part will be described below. 【0030】 The information acquisition unit 210 acquires the above input data from the database 300, performs data cleansing on the input data, further organizes the data, and then stores the input data in the data storage unit 220. The data storage unit 220 stores the data acquired by the information acquisition unit 210. The data storage unit 220 also performs data update. 【0031】 The selection unit 230 selects the one with the largest impedance among the impedances of the plurality of wirings connected to the multi-direction SCCB using the data read from the data storage unit 220, and transmits the current interruption threshold of the SCCB connected to that wiring and related data to the calculation unit 240. 【0032】The calculation unit 240 calculates the cooperation capacitor capacitance C using the data selected by the selection unit 230. ｃ The output unit 250 outputs the calculation result of the calculation unit 240. 【0033】 (System configuration example on the DC power supply system side) As system configuration examples on the DC power supply system side, there are those shown in FIGS. 1 to 3. FIG. 5 shows a configuration example of the three-way SCCB 100 when acquiring design information. FIG. 5 shows an example in which the three-way SCCB 100 is installed at the connection point (branch point) of the main line and the branch line. 【0034】 Note that the calculation method of the cooperation capacitor capacitance C according to the present invention is applied to each three-way SCCB constituting the DC power supply system, and the cooperation capacitor capacitance C ｃ may be calculated individually, or the cooperation capacitor capacitance C ｃ may be calculated based on the largest wiring impedance in the DC power supply system, and that value may be applied to all the three-way SCCBs constituting the DC power supply system. ｃ 【0035】 The three-way SCCB 100 shown in FIG. 5 is a device formed by combining three one-way SCCBs 1 to 3 and one cooperation capacitor 10 into one SCCB. The three one-way SCCBs are connected outward at one point, and the cooperation capacitor 10 is installed at the intersection point. 【0036】 FIG. 6 shows a detailed configuration example of the three-way SCCB 100. FIG. 6 also shows a measurement unit for measuring the current value. FIG. 6 shows an example when a three-way circuit breaker is realized using semiconductor elements (e.g., MOSFETs), but this is just one example. It is also possible to realize a three-way circuit breaker using functional parts other than semiconductor elements. For example, a three-way circuit breaker may be realized by combining a relay or an electromagnetic contactor and a current detection unit. As the current detection unit, for example, a Hall element or a shunt resistor can be used. 【0037】 Each of A to F in FIG. 6 contains a capacitor or a diode. Specifically, for example, diodes are included in A, D, and F, and capacitors are included in B, C, and E. 【0038】 In this embodiment, a three-directional SCCB 100 is used as an example of a multi-directional SCCB, but the number of directions (number of SCCBs) is not limited to three. The number of directions (number of SCCBs) may be one, two, or four or more. 【0039】 (Regarding the processing of the calculation unit 240) The calculation unit 240 uses the input data to determine the capacitance C of the coordinating capacitor 10 required for the SCCB to shut off. ｃ The following is calculated. Input data may include the design information mentioned above, or it may utilize the results of simulations or experiments (current interruption waveform data). 【0040】 In the case of a multi-directional SCCB, the short-circuit current flows to the short-circuit point with the coordinating capacitor 10 as the power source. Therefore, the current i(t) discharged from the coordinating capacitor 10 can be expressed by the following equation. 【0041】 The above equation represents the current i(t) (time change of current during transient phenomena) when the switch SW is turned ON at t = 0s in an RL circuit consisting of a resistor R [Ω], an inductor (coil) L [H], a DC power supply E [V], and a switch SW. 【0042】 In the above equation, E corresponds to the rated voltage of the DC power supply system, R corresponds to the resistance of the wiring connected to the SCCB through which the short-circuit current flows, and L corresponds to the inductance of the said wiring. 【0043】 An SCCB through which a short-circuit current flows will have the current cutoff threshold I ｔｈ The current is immediately cut off when it reaches [A]. 【0044】 As shown in Figure 7, the calculation unit 240 calculates from the short-circuit start time 0s to the SCCB trip start time T ｔ The integral of the current value up to [s] represents the amount of charge Q discharged from the coordinating capacitor 10 from the time the short-circuit current starts flowing until it trips. ｓ [C] can be calculated. 【0045】 The calculation unit 240 calculates the charge quantity Q. ｓ [C] is the area of ​​the triangle (1 / 2 x T ｔ [s]xIｔｈ [A]) can be used as an approximation for calculation. Furthermore, to more accurately calculate and more closely resemble the actual circuit, the charge quantity Q can be obtained from the simulation's current cutoff waveform data. ｓ You may calculate [C]. 【0046】 If we let Q be the electric charge, C be the capacitance, and V be the voltage across the capacitor, then Q = CV holds true. By rearranging this equation, C can be calculated as C = Q / V. 【0047】 The calculation unit 240 is C ｃ [F] = Q ｓ [C] / 380[V] (when the rated voltage is DC380V) is used to determine the capacitance C of the coordination capacitor 10. ｃ Calculate [F]. 【0048】 As mentioned above, approximation formulas may be used as needed during the calculation process. Furthermore, the formulas used are not limited to those in "Equation 1" above; any formula that closely resembles the actual circuit may be used. For example, when considering an RLC series circuit, the following formula for an RLC series circuit may be used. 【0049】 The meaning of the symbols in the above formula is as follows: 【0050】 ・T ｔ : Time from the time of short circuit occurrence to the start of tripping C ｃ : Capacitance of the coordinating capacitor, L: Inductance component of the wiring impedance, R: Resistive component of the wiring impedance (Example of operation of the capacitor capacitance determination device 200) Referring to the flowchart in Figure 8, the basic operation flow of the capacitor capacitance determination device 200 will be explained. 【0051】 <S101> In S101, the information acquisition unit 210 inputs data such as design information to the capacitor capacitance determination device 200. Specifically, the data described in (1) to (5) above is input. In the following explanation, the SCCB in direction n will be referred to as SCCBn. The input data is stored in the data storage unit 220. 【0052】<S102> In S102, the selection unit 230 compares the wiring impedances of the wiring connected to SCCB1 to SCCBn and selects the SCCB with the largest wiring impedance from among the n SCCBs in the multi-directional SCCB. For example, if the relationship of the magnitudes of the wiring impedances is "SCCB1 < SCCB2 < SCCB3", then SCCB3 is selected. 【0053】 <S103> In S103, the selection unit 230 extracts the current cutoff threshold of the SCCB (e.g., SCCB3) selected in S102, the rated voltage of the DC power supply system, and the wiring impedance of the wiring connected to the selected SCCB (e.g., SCCB3). The extracted information is passed to the calculation unit 240. 【0054】 <S104> In S104, the calculation unit 240 uses the calculation method described above to determine the capacitance C of the coordinating capacitor 10. ｃ Calculate. 【0055】 <S105> In S105, the calculation unit 240 calculates the capacitance C of the coordinating capacitor 10. ｃ The correction is performed. Specifically, the calculation unit 240 calculates the capacity C in S104 using a correction coefficient (1 or more, for example 1.5) as a specified safety factor (buffer). ｃ By multiplying by this, the final capacity C ｃ Derive the following. 【0056】 <S106> In S106, the output section 250 has a capacitance C of the coordinating capacitor 10 corrected in S105. ｃ Outputs. 【0057】 (Example of operation of capacitor capacitance determination device 200) Referring to the flowchart in Figure 9, the operation flow of the capacitor capacitance determination device 200 when there are multiple SCCBs with different cutoff thresholds will be explained. 【0058】<S201> In S201, the information acquisition unit 210 inputs data such as design information to the capacitor capacitance determination device 200. Specifically, the data described in (1) to (5) above is input. In the following explanation, the SCCB in direction n will be referred to as SCCBn. The input data is stored in the data storage unit 220. 【0059】 <S202> In S202, the selection unit 230 compares the wiring impedances of the wiring connected to a plurality of SCCBs with the same cutoff threshold, and selects the SCCB with the largest wiring impedance from among the plurality of SCCBs. 【0060】 For example, suppose the cutoff thresholds for SCCB1 and SCCB3 are 30A each, and the cutoff threshold for SCCB2 is 10A. In this case, in the first loop (loop S202 to S205), the selection unit 230 determines that SCCB1 < SCCB3 and selects SCCB1. In the second loop, the selection unit 230 selects SCCB2. 【0061】 <S203> In S203, the selection unit 230 extracts SCCB-related information for the selected SCCB. Specifically, the selection unit 230 extracts the current cutoff threshold of the SCCB (e.g., SCCB3) selected in S202, the rated voltage of the DC power supply system, and the wiring impedance of the wiring connected to the selected SCCB (e.g., SCCB3). The extracted information is passed to the calculation unit 240. 【0062】 <S204> In S204, the calculation unit 240 calculates the SCCB in the current loop according to the calculation method described above, the coordinating capacitor capacitance C ｃ Calculate. 【0063】 <S205> In S205, the calculation unit 240 determines whether there are other SCCBs with different cutoff thresholds. If there are, proceed to S202; otherwise, proceed to S206. 【0064】 <S206> When there are multiple SCCB cutoff thresholds (i.e., multiple coordinating capacitor capacitances C) ｃIf there is a calculation result, in S206, the calculation unit 240 calculates the capacitance of multiple coordinating capacitors C ｃ A comparison was made between them, and the largest coordinating capacitor capacitance C was found. ｃ Select the following. 【0065】 <S207> In S207, the calculation unit 240 calculates the capacitance C of the coordinating capacitor determined in S206. ｃ The correction is performed. Specifically, the calculation unit 240 calculates a correction coefficient (a value of 1 or more, for example 1.5) as a specified safety factor (buffer) for the capacity C obtained in S206. ｃ By multiplying by this, the final capacity C ｃ Derive the following. 【0066】 <S208> In S208, the output section 250 has a capacitance C of the coordinating capacitor 10 corrected in S207. ｃ Outputs. 【0067】 (Example) Next, as an example, a more specific calculation example in the flow shown in Figure 8 will be described. In this example, a three-way SCCB 100 shown in Figure 10 is used as the multi-way SCCB. In this example, the capacitor capacitance determination device 200 determines the capacitance C of the coordinating capacitor 10 shown in Figure 10. ｃ To decide. 【0068】 <S101> In S101, the information acquisition unit 210 inputs the input data to the capacitor capacitance determination device 200. The input data (1) to (5) in the case shown in Figure 10 are as follows. 【0069】 (1) Number of directions of the multi-directional SCCB: n (n = 1, 2, 3, ...) = 3 (2) Impedance (cross-sectional area, length) of the wiring connected to the multi-directional SCCB The input data regarding the wiring impedance is as follows. 【0070】 - Wiring resistance connected to SCCB1 = 2Ω, inductance = 0.3mH - Wiring resistance connected to SCCB2 = 4Ω, inductance = 0.6nH - Wiring resistance connected to SCCB3 = 6Ω, inductance = 1mH In this embodiment, for simplicity, resistance is mainly used as impedance. 【0071】 (3) Current interruption thresholds for each direction of the multi-directional SCCB: ・Current interruption threshold for SCCB1: 30A ・Current interruption threshold for SCCB2: 30A ・Current interruption threshold for SCCB3: 30A (4) Rated voltage of the DC power supply system = DC 380V (5) Correction coefficient = 5, margin coefficient = 1.5 Note that the correction coefficient and margin coefficient may be collectively referred to as the "correction coefficient". 【0072】 <S102> In S102, the selection unit 230 compares the wiring impedances of SCCB1 to SCCB3 and selects the SCCB with the highest wiring impedance. In this embodiment, since "SCCB1 (2Ω) < SCCB2 (4Ω) < SCCB3 (6Ω)", SCCB3, which has the highest wiring impedance, is selected. 【0073】 <S103> In S103, the selection unit 230 extracts the following information from the data storage unit 220 as information about the selected SCCB3. 【0074】 - Wiring resistance connected to SCCB3 = 6Ω, inductance = 1mH - Current cutoff threshold of SCCB3 = 30A - Rated voltage of DC power supply system = DC380V - Correction coefficient = 5 - Safety margin coefficient = 1.5 <S104> In S104, the calculation unit 240 calculates the capacitance C of the coordinating capacitor 10 ｃ First, the calculation unit 240 uses the formula for current i(t) shown in "Equation 1" to determine the time from the start of discharge of the coordinating capacitor 10 (t=0s) until the current reaches the current cutoff threshold. 【0075】 In this embodiment, by substituting E = 380V, R = 6Ω, L = 1mH, and i(t) = 30A into equation "Equation 1" and solving for t, we obtain t = approximately 110μs. 【0076】 As shown in Figure 11, the calculation unit 240 integrates the current i(t) shown in "Equation 1" from t=0s to t=110μs to calculate the amount of charge Q discharged by the coordinating capacitor 10 from t=0s to t=110μs. ｓ Calculate. 【0077】More specifically, the calculation unit 240 approximates the charge quantity Qs [C] by the area of ​​the triangle shown in Figure 11, as described below. 【0078】 Qs=1 / 2x110μsx30A=1.65x10 －３ C Calculation unit 240 is the cooperative capacitor capacitance C ｃ [F] is calculated from Q = CV as follows. 【0079】 C=Q / V=1.65x10 －３ C / 380V = 14μF <S105> In S105, the calculation unit 240 calculates the capacitance C of the coordinating capacitor calculated in S104. ｃ This is multiplied by the "capacitor correction factor and safety factor" obtained experimentally or empirically. For example, if the correction factor is 5 and the safety factor is 1.5, the calculation unit 240 calculates the coordinating capacitor capacitance C ｃ [F] is calculated as follows. 【0080】 Cc = 14μF x 5 x 1.5 = 105μF <S106> In S106, the output section 250 has a coordinating capacitor capacitance C ｃ Outputs 105μF. 【0081】 (Example Hardware Configuration) The capacitor capacitance determination device 200 described in this embodiment can be realized, for example, by having a computer execute a program. This computer may be a physical computer or a virtual machine on the cloud. 【0082】 In other words, the capacitor capacitance determination device 200 can be realized by using hardware resources such as a CPU and memory built into a computer to execute a program corresponding to the processing performed by the capacitor capacitance determination device 200. The above program can be recorded on a computer-readable recording medium (such as portable memory), saved, and distributed. It is also possible to provide the above program via a network such as the Internet or email. 【0083】Figure 12 shows an example of the hardware configuration of the computer described above. The computer in Figure 12 has a drive device 1000, an auxiliary storage device 1002, a memory device 1003, a CPU 1004, an interface device 1005, a display device 1006, an input device 1007, an output device 1008, etc., all of which are interconnected by bus B. The computer may also be equipped with a GPU. 【0084】 The program that enables processing on the computer is provided on a recording medium 1001, such as a CD-ROM or memory card. When the recording medium 1001 containing the program is set in the drive device 1000, the program is installed from the recording medium 1001 to the auxiliary storage device 1002 via the drive device 1000. However, the program does not necessarily have to be installed from the recording medium 1001; it may also be downloaded from another computer via a network. The auxiliary storage device 1002 stores the installed program as well as necessary files and data. 【0085】 The memory device 1003 reads and stores a program from the auxiliary storage device 1002 when a program startup command is received. The CPU 1004 implements the functions related to the capacitor capacitance determination device 200 according to the program stored in the memory device 1003. The interface device 1005 is used as an interface for connecting to a network, etc. The display device 1006 displays a GUI (Graphical User Interface) etc. based on the program. The input device 1007 consists of a keyboard and mouse, buttons, or a touch panel etc., and is used to input various operation commands. The output device 1008 outputs the calculation results. 【0086】(Effects of the Embodiment) As described above, the technology described in this embodiment makes it possible to determine the capacitance of a coordinating capacitor without having to incorporate it into an actual DC power supply system for verification, or without having to incorporate it into an experimental system that simulates a DC power supply system for verification, thereby reducing these costs. In addition, the time required for verification can be reduced, enabling rapid system design. 【0087】 The following additional information is disclosed regarding the embodiments described above. 【0088】<Notes> (Note 1) A capacitor capacity determination device for determining the capacity of a coordinating capacitor used in a DC power supply system, comprising a calculation unit that uses the impedance of the wiring connected to the circuit breaker and the rated voltage of the DC power supply system to calculate the amount of charge discharged from the coordinating capacitor from the discharge start time of the coordinating capacitor until the time when the magnitude of the current flowing through the circuit breaker reaches the current interruption threshold of the circuit breaker, and calculates the capacity from the amount of charge and the rated voltage. (Note 2) The capacitor capacity determination device according to Note 1, further comprising a selection unit that selects the circuit breaker from the plurality of circuit breakers in which the impedance of the wiring to which the capacitor is connected is the maximum, in the case where the coordinating capacitor is connected to a plurality of circuit breakers with the same current interruption threshold, wherein the calculation unit calculates the capacity using the impedance of the wiring connected to the circuit breaker selected by the selection unit and the rated voltage of the DC power supply system. (Note 3) A capacitor capacitance determination method to be performed by a capacitor capacitance determination device for determining the capacitance of a coordinating capacitor used in a DC power supply system, comprising a calculation step of using the impedance of the wiring connected to the circuit breaker and the rated voltage of the DC power supply system to calculate the amount of charge discharged from the coordinating capacitor from the discharge start time of the coordinating capacitor until the time when the magnitude of the current flowing to the circuit breaker reaches the current interruption threshold of the circuit breaker, and calculating the capacitance from the amount of charge and the rated voltage. (Note 4) A non-temporary storage medium storing a program for causing a computer to function as a capacitor capacitance determination device as described in Note 1 or 2. 【0089】 Although this embodiment has been described above, the present invention is not limited to this specific embodiment, and various modifications and changes are possible within the scope of the gist of the invention as described in the claims. 【0090】 1-3 SCCB 10 Coordination capacitor 100 Three-way SCCB 200 Capacitor capacitance determination device 210 Information acquisition unit 220 Data storage unit 230 Selection unit 240 Calculation unit 250 Output unit 300 DB

Claims

1. A capacitor capacitance determination device for determining the capacitance of a coordinating capacitor used in a DC power supply system, comprising a calculation unit that uses the impedance of the wiring connected to a circuit breaker and the rated voltage of the DC power supply system to calculate the amount of charge discharged from the coordinating capacitor from the discharge start time of the circuit breaker until the time when the magnitude of the current flowing through the circuit breaker reaches the current interruption threshold of the circuit breaker, and calculates the capacitance from the amount of charge and the rated voltage.

2. The capacitor capacitance determination device according to claim 1, further comprising a selection unit that selects from the plurality of circuit breakers the circuit breaker having the highest impedance of the connected wiring when the coordinating capacitor is connected to a plurality of circuit breakers having the same current interruption threshold, wherein the calculation unit calculates the capacitance using the impedance of the wiring connected to the circuit breaker selected by the selection unit and the rated voltage of the DC power supply system.

3. A capacitor capacitance determination method to be performed by a capacitor capacitance determination device for determining the capacitance of a coordinating capacitor used in a DC power supply system, comprising a calculation step of using the impedance of the wiring connected to the circuit breaker and the rated voltage of the DC power supply system to calculate the amount of charge discharged from the coordinating capacitor from the discharge start time of the coordinating capacitor until the time when the magnitude of the current flowing to the circuit breaker reaches the current interruption threshold of the circuit breaker, and calculating the capacitance from the amount of charge and the rated voltage.

4. A program for causing a computer to function as a capacitor capacitance determination device according to claim 1 or 2.

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