Power supply system
The power supply system addresses power loss and fault management in DC distribution systems by using a relaxation reactor and fault detection to mitigate surge voltages and isolate faults, enhancing system reliability.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- KK TOYOTA CHUO KENKYUSHO
- Filing Date
- 2023-02-22
- Publication Date
- 2026-07-22
AI Technical Summary
Conventional DC high-voltage transmission systems experience significant power losses due to multiple series reactors when there are many connection points, particularly in distribution systems, and struggle to effectively manage sudden current changes caused by accidents like short circuits and ground faults.
A power supply system design with a relaxation reactor connected between two power lines - one being a power supply line and the other a power demand line - to mitigate surge voltages and suppress power loss, incorporating a fault detector and disconnection device to manage system faults.
The system effectively mitigates sudden current changes and suppresses power loss due to voltage fluctuations, while ensuring reliable detection and isolation of faults in DC power distribution systems.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a power supply system.
Background Art
[0002] As a technique for detecting an accident section such as a short circuit in a high-voltage DC power transmission system, a technique (series reactor method) of inserting a reactor in series with a line at both ends of a power transmission line has been disclosed (Non-Patent Document 1). In the series reactor method, the rate of change of the voltage on the power transmission line side of the reactors connected in series is measured. When a system accident occurs in the power transmission line, since the voltage of the power transmission line changes steeply due to the surge voltage generated by the accident, the accident is detected by using the action of smoothing the surge voltage by the reactor.
[0003] Also, in a DC power transmission line connected to a DC bus connected to the DC side of a power converter that converts AC and DC with each other, a power transmission system including a parallel capacitor, a current detector, and an accident determination device has been disclosed (Patent Document 1). The parallel capacitor is connected between the power transmission line and the ground at the end of the DC power transmission line. The current detector detects the current flowing through the parallel capacitor. The accident determination device performs an operation on the current value detected by the current detector and determines the presence or absence of an accident in the power transmission line. Note that a reactor may be connected between the DC bus and the power transmission line to form a low-pass filter together with the parallel capacitor.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Non-Patent Documents
[0005]
Non-Patent Document 1
[0006] Conventional technology relates to DC high-voltage transmission systems and is designed for situations where there are few systems on both the transmitting and receiving sides. Therefore, when there are many connection points in power lines such as distribution systems, connecting multiple series reactors between power lines results in large power losses in the reactors when voltage fluctuations other than those caused by faults occur. [Means for solving the problem]
[0007] One aspect of the present invention is a power supply system that supplies power in direct current, comprising a first power line in which the sum of the maximum power supplied by connected devices is equal to or greater than or equal to the sum of the maximum power demanded by connected devices, and a second power line in which the sum of the maximum power supplied by connected devices is less than the sum of the maximum power demanded by connected devices, wherein the relay point between the first power line and the second power line is connected by a relaxation reactor.
[0008] Here, the mitigation reactor is preferably a reactor for mitigating surge voltages caused by a system fault occurring in the first power line or the second power line.
[0009] Furthermore, it is preferable that the first power line is a power supply line and the second power line is a power demand line.
[0010] Furthermore, it is preferable that a series reactor is connected to the DC side of the AC / DC power converter that supplies power to the first power line and the second power line.
[0011] Furthermore, it is preferable to include a fault detector that detects a system fault occurring in the first power line or the second power line.
[0012] Furthermore, it is preferable to include a disconnection device that disconnects the power line where the fault was detected from the system when a fault is detected by the fault detector. [Effects of the Invention]
[0013] According to the present invention, in a DC power distribution system connecting DC power lines, it is possible to mitigate sudden current changes caused by accidents such as short circuits and ground faults, while suppressing power loss due to voltage fluctuations other than accidents. [Brief explanation of the drawing]
[0014] [Figure 1] This is a diagram showing the configuration of the power supply system in the first embodiment. [Figure 2] This diagram shows the relationship between the number of reactors and power surges. [Figure 3] This diagram shows the configuration of another example of the power supply system in the first embodiment. [Figure 4] This diagram shows the configuration of another example of the power supply system in the first embodiment. [Figure 5] This is a diagram showing the configuration of the power supply system in the second embodiment. [Figure 6] This figure shows the configuration of another example of a power supply system in the second embodiment. [Modes for carrying out the invention]
[0015] [First Embodiment] The power supply system 100 in the first embodiment is configured to include power lines 10 (10a, 10b) and a relaxation reactor 12, as shown in Figure 1.
[0016] The power line 10 is a wire for supplying direct current power. The power line 10 is connected to a bus connected to an AC generator via an AC-DC power converter and is used to supply the direct current power supplied from the bus to a load. In the power supply system 100, a plurality of power lines 10 are laid out to supply power to various locations. The power line 10 has a positive electrode side and a negative electrode side. In FIG. 1, the power line 10 on the positive electrode side is shown as a solid line, and the power line 10 on the negative electrode side is shown as a dashed line.
[0017] In the power supply system 100, a relaxation reactor 12 for voltage relaxation is connected between the power lines 10 at the relay points of the plurality of power lines 10 that are the objects to detect accidents. The relaxation reactor 12 is provided to relax the sharp change in the voltage of the power line 10 due to the surge voltage generated by the system accident when a system accident such as a short circuit occurs in the power line 10. The relaxation reactor 12 is connected between the first power line 10a and the second power line 10b.
[0018] Here, the first power line 10a is a power line connecting the power source and the second power line 10b. The first power line 10a is a circuit with a large power supply amount. That is, the first power line 10a is a power line in which the total maximum supply power of the connected devices is greater than or equal to the total maximum demand power. Generally, the first power line 10a is regarded as a power supply line for supplying power. The second power line 10b is a circuit with a large power demand amount. That is, the second power line 10b is a circuit in which the total maximum supply power of the connected devices is less than the total maximum demand power. Generally, the second power line 10b is regarded as a power demand line connected to a load. The second power line 10b is connected to an AC-DC power converter connected to the first power line 10a via at least one relaxation reactor 12.
[0019] By configuring the relaxation reactor 12 to be connected between the first power line 10a and the second power line 10b in this way, a rapid current change due to an accident such as a short circuit or a ground fault occurring in the power line 10 can be relaxed by the relaxation reactor 12. On the other hand, since the relaxation reactor 12 for relaxation is provided only between the first power line 10a and the second power line 10b, the power loss in the power supply system 100 with respect to voltage fluctuations other than accidents can be suppressed.
[0020] FIG. 2 shows the relationship between the number of reactors connected to the power line and the magnitude of the current surge. Assuming that there is a power line with an inductance of 10 μH and a resistance of 0 Ω, and a 100 Ω load resistance is connected in series thereto, the current when the load resistance is changed from 100 Ω to 0 Ω for 1 millisecond (1 msec) while a DC voltage of 360 V is applied to this load resistance is shown. In FIG. 2, the current when 0 to 4 reactors of 100 μH are connected in series to the power line is shown. As shown in FIG. 2, even with one reactor, the current surge can be suppressed even when the power line suddenly changes to a state close to a short circuit.
[0021] In consideration of the power loss in the power line, it is not preferable to connect a large number of relaxation reactors 12 between the power supply device (for example, an AC-DC power converter) and the power demand device (for example, a load). Therefore, by connecting the relaxation reactor 12 only at the relay point between the first power line 10a and the second power line 10b as in the power supply system 100 of the present embodiment, the current surge in a system accident can be suppressed and the power loss due to the relaxation reactor 12 can be reduced.
[0022] Also, as shown in FIG. 3, an accident detector 14 for detecting voltage fluctuations of each of the first power line 10a and the second power line 10b may be provided. In FIG. 3, since the arrangement of the relaxation reactor 12 is the same as that in FIG. 1, the reference numerals are omitted.
[0023] As shown in Figure 3, the fault detector 14 may include a capacitor and a sensor that detects fluctuations in the voltage across the terminals of the capacitor. However, the configuration of the fault detector 14 is not limited to this, and any device capable of detecting voltage fluctuations in the first power line 10a and the second power line 10b is acceptable. The fault detector 14 may also be equipped with a disconnection device to disconnect the power line 10 in which a fault such as a short circuit has been detected from the power supply system 100.
[0024] Furthermore, as shown in Figure 4, the fault detector 14 may be configured to have a fault detector 15 installed between the positive power line 10 and the negative power line 10. Note that in Figure 4, the arrangement of the relaxation reactor 12 and the capacitor of the fault detector 14 is the same as in Figure 3, so the reference numerals have been omitted. By providing the fault detector 15 in this way, the power supply system 100 can more reliably detect ground faults between the positive power line 10 or the negative power line 10, or short circuits between the positive power line 10 and the negative power line 10. The fault detector 15 may also be equipped with a disconnection device to disconnect the power line 10 in which a fault such as a short circuit has been detected from the power supply system 100.
[0025] [Second Embodiment] The power supply system 102 in the second embodiment is configured to include power lines 10 (10a, 10b), a relaxation reactor 12, and a series reactor 16, as shown in Figure 5. In the power supply system 102, a specific monitoring area X is set. In Figure 5, the specific monitoring area X is shown as a hatched area. The arrangement of the relaxation reactor 12 is the same as in the power supply system 100 shown in Figure 1, so the reference numerals have been omitted.
[0026] The designated monitoring area X is an area where the effects of an accident such as a short circuit occurring within the designated monitoring area X are suppressed from spreading to areas outside of the designated monitoring area X. In the power supply system 102, a series reactor 16 is connected in series with the power line 10 so as to surround the designated monitoring area X. The series reactor 16 is provided to mitigate the abrupt change in the voltage of the power line 10 in the event of a system accident such as a short circuit in the power line 10 within the designated monitoring area X, in order to prevent the effects of surge voltages caused by the system accident from spreading beyond the designated monitoring area X.
[0027] In the power supply system 102 of this embodiment, the power loss in the power line 10 is greater than in the power supply system 100 of the first embodiment due to the addition of the series reactor 16, but the effect of suppressing current surges in response to system faults within the specific monitoring area X can be enhanced. Therefore, it is possible to more effectively prevent the effects of a fault within the specific monitoring area X from spreading outside the specific monitoring area X.
[0028] Furthermore, as shown in Figure 6, a fault detector 14 may be provided to detect voltage fluctuations in the first power line 10a and the second power line 10b within a specific monitoring area X. Note that in Figure 6, the arrangement of the relaxation reactor 12 and the series reactor 16 is the same as in Figure 5, so the reference numerals have been omitted. The fault detector 14 may also be equipped with a disconnection device to disconnect the power line 10 in which a fault such as a short circuit has been detected from the power supply system 100.
[0029] [Structure of the invention] [Configuration 1] A power supply system that supplies power using direct current, The first power line is one in which the sum of the maximum power supplied by connected devices is greater than or equal to the sum of the maximum power demanded, The second power line is one in which the sum of the maximum power supplied by the connected devices is less than the sum of the maximum power demanded by the connected devices. Includes, A power supply system characterized in that the relay point between the first power line and the second power line is connected by a relaxation reactor. [Configuration 2] The power supply system described in Configuration 1, A power supply system characterized in that the mitigation reactor is a reactor for mitigating surge voltages caused by a system fault occurring in the first power line or the second power line. [Configuration 3] A power supply system as described in configuration 1 or 2, The aforementioned first power line is a power supply line, A power supply system characterized in that the second power line is a power demand line. [Structure 4] A power supply system as described in any one of items 1 to 3, A power supply system characterized in that a series reactor is connected to the DC side of an AC / DC power converter that supplies power to the first power line and the second power line. [Composition 5] A power supply system as described in any one of items 1 to 4, A power supply system characterized by comprising a fault detector for detecting a system fault occurring in the first power line or the second power line. [Composition 6] The power supply system described in configuration 5, A power supply system characterized by comprising a disconnection device that disconnects the power line in which a fault is detected from the system when a fault is detected by the fault detector. [Explanation of symbols]
[0030] 10 Power lines, 10a First power line, 10b Second power line, 12 Relaxation reactor, 14 Fault detector, 15 Fault detector, 16 Series reactor, 100, 102 Power supply system.
Claims
1. A power supply system that supplies power using direct current, Among the multiple power lines branching off from the busbar connected to the DC side of the AC / DC power converter, The sum of the maximum power supply from connected devices is greater than or equal to the sum of the maximum power demand, and multiple first power lines are connected to each other, The sum of the maximum power supply from connected devices is less than the sum of the maximum power demand, and multiple second power lines connected to each other, Includes, A power supply system characterized in that all relay points between the first power line and the second power line are connected by relaxation reactors.
2. A power supply system according to claim 1, A power supply system characterized in that the mitigation reactor is a reactor for mitigating surge voltages caused by a system fault occurring in the first power line or the second power line.
3. A power supply system according to claim 1 or 2, The aforementioned first power line is a power supply line. A power supply system characterized in that the second power line is a power demand line.
4. A power supply system according to claim 1, A power supply system characterized in that a series reactor is connected to the DC side of the AC / DC power converter that supplies power to the first power line and the second power line.
5. A power supply system according to claim 1, A power supply system characterized by comprising a fault detector for detecting a system fault occurring in the first power line or the second power line.
6. A power supply system according to claim 5, A power supply system characterized by comprising a disconnection device that disconnects the power line in which a fault is detected from the system when a fault is detected by the fault detector.