Power supply system and power supply method

Abstract

To suppress power consumption in a resistor while preventing a power generator of a mobile power supply vehicle from stopping.SOLUTION: A reverse power flow prevention device 3 comprises: a switch 31 connected in parallel with a device on a power reception side in a power supply path 4 for connecting a device on a power transmission side of power with the device on the power reception side of the power; a load 32 for preventing reverse power flow connected in series with the switch 31; and a controller 30 which monitors current i flowing from the power transmission side to the power reception side in the power supply path 4, turns the switch 31 off when the current i is larger than a first threshold ith1, and turns the switch 31 on when the current i is lower than the first threshold ith1.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a reverse power flow prevention device, a power supply system, and a power supply method, and more particularly to a technique for preventing the occurrence of reverse power flow when power is supplied from a mobile power supply vehicle to a consumer equipped with a distributed power supply device. [Background technology]

[0002] Power supply vehicles (mobile power supply vehicles) are generally known as temporary power sources that supply electricity to customers in buildings and ordinary homes during large-scale power outages caused by disasters, during construction and inspection of power distribution lines, etc. A mobile power supply vehicle is a mobile, private power generating device that is equipped with a prime mover, generator, and auxiliary equipment on a vehicle such as a truck or trailer.

[0003] In recent years, there are cases where a distributed power supply device such as a photovoltaic apparatus is installed at a consumer to which a mobile power supply vehicle is connected and is connected to a power distribution system. When power is supplied from a mobile power supply vehicle to such a consumer, if the distributed power supply device generates power that exceeds the consumer's demand, a reverse power flow of power occurs from the distributed power supply device to the mobile power supply vehicle.

[0004] When a reverse power flow occurs, the generator of a mobile power supply vehicle will stop. Once the generator of a mobile power supply vehicle stops, it takes time to restart the generator, and a power outage occurs during that time. Therefore, when using a mobile power supply vehicle, it is extremely important not to stop the generator.

[0005] Conventionally, a technique for preventing reverse power flow to a mobile power supply vehicle is known in which a resistor is connected to the generator of the mobile power supply vehicle (see, for example, Patent Document 1). According to this, power is constantly consumed by the resistor, so the occurrence of reverse power flow to the mobile power supply vehicle is prevented, and it is possible to avoid the generator of the mobile power supply vehicle stopping. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2020-32770 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, if a resistor is constantly connected to the generator of a mobile power supply vehicle, power will be constantly consumed in the resistor, resulting in unnecessary consumption of fuel for the prime mover used to drive the generator, shortening the operating time of the mobile power supply vehicle and reducing the efficiency of the mobile power supply vehicle.

[0008] The present invention has been made in consideration of the above-mentioned problems, and has an object to suppress power consumption in resistors while preventing the generator of a mobile power supply vehicle from stopping. [Means for solving the problem]

[0009] A reverse power flow prevention device according to a representative embodiment of the present invention is characterized in that it comprises a switch connected in parallel with a power receiving device in a power supply path connecting a power transmitting device and a power receiving device, a load for preventing reverse power flow connected in series with the switch, and a control device that monitors the current flowing from the power transmitting side to the power receiving side in the power supply path, turns off the switch when the current is greater than a first threshold value, and turns on the switch when the current is lower than the first threshold value. Effect of the Invention

[0010] The reverse power flow prevention device according to the present invention makes it possible to prevent the generator of the mobile power supply vehicle from stopping, while suppressing power consumption in the resistor. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram showing a configuration of a power supply system according to an embodiment of the present invention; [Diagram 2]1 is a diagram showing a specific configuration of a mobile power supply vehicle and a reverse power flow prevention device in a power supply system according to an embodiment of the present invention. FIG. [Figure 3A] 5A to 5C are diagrams for explaining the operation of the reverse power flow prevention device according to the embodiment of the present invention. [Figure 3B] 5A to 5C are diagrams for explaining the operation of the reverse power flow prevention device according to the embodiment of the present invention. [Figure 4] 5 is a flowchart showing an example of an operation flow related to power supply by the power supply system according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] 1. Overview of the embodiment First, a typical embodiment of the invention disclosed in this application will be outlined. In the following description, as an example, reference numerals in the drawings corresponding to components of the invention are given in parentheses.

[0013] [1] A reverse power flow prevention device (3) according to a representative embodiment of the present invention is characterized in that it comprises a switch (31) connected in parallel with a power receiving device in a power supply path (4) connecting a power transmitting device and a power receiving device, a load (32) for preventing reverse power flow connected in series with the switch, and a control device (30) that monitors a current (i) flowing from the power transmitting side to the power receiving side in the power supply path, turns off the switch when the current is greater than a first threshold value (ith1), and turns on the switch when the current is lower than the first threshold value.

[0014] [2] In the reverse power flow prevention device described in [1] above, the control device may turn off the switch if the state in which the current exceeds a second threshold (ith2) lower than the first threshold continues for a predetermined time (T1) after the switch is turned on.

[0015] [3] In the reverse power flow prevention device described in [2] above, the control device may output a detection signal (St) when the current becomes lower than the second threshold value.

[0016] [4] A power supply system (1) according to a representative embodiment of the present invention comprises the reverse power flow prevention device described in [3] above, and a mobile power supply vehicle (2) as the power transmission side device that supplies power to consumer equipment (5_1 to 5_n) as the power receiving side device via the power supply path, the consumer equipment including a distributed power supply device (50) linked to a power distribution system, and the mobile power supply vehicle is characterized in that when the detection signal is output from the control device while supplying power to the consumer equipment, the mobile power supply vehicle stops the isolated operation of the distributed power supply device.

[0017] [5] In the power supply system described in [4] above, the mobile power supply vehicle may increase the voltage supplied to the power supply path to stop the independent operation of the distributed power supply device.

[0018] [6] In the power supply system described in [4] above, the mobile power supply vehicle may fluctuate the frequency of the voltage supplied to the power supply path to stop the independent operation of the distributed power supply device.

[0019] [7] A method according to a representative embodiment of the present invention is a method for supplying power to consumer equipment (5_1 to 5_n) including a mobile power supply vehicle (2), a load (32) for preventing reverse power flow connectable in parallel to the consumer equipment on a power supply path (4) connecting the mobile power supply vehicle to the consumer equipment, the load (32) for preventing reverse power flow, and a control device (30) for controlling connection of the load to the power supply path. The power supply method includes a first step (S2) in which the mobile power supply vehicle supplies power to the power supply path, a second step (S3) in which the control device monitors a current (i) flowing from the mobile power supply vehicle to the consumer equipment in the power supply path, a third step (S5) in which the control device disconnects the load from the power supply path when the current is higher than a first threshold, and a fourth step (S6) in which the control device connects the load to the power supply path when the current becomes lower than the first threshold.

[0020] [8] The power supply method described in [7] above may further include a fifth step (S8, S9) in which, if, after the fourth step, the state in which the current exceeds a second threshold (ith2) lower than the first threshold continues for a predetermined time (T1), the control device disconnects the load from the power supply path.

[0021] [9] The power supply method described in [8] above may further include a sixth step (S10) in which the control device outputs a detection signal (St) when the current becomes lower than the second threshold value after the fourth step, and a seventh step (S11) in which the mobile power supply vehicle stops the independent operation of the distributed power supply device when the detection signal is output from the control device.

[0022] 2. Specific examples of embodiments DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific examples of embodiments of the present invention will be described with reference to the drawings. In the following description, components common to the respective embodiments are designated by the same reference numerals, and repeated description will be omitted.

[0023] FIG. 1 is a diagram showing a configuration of a power supply system according to an embodiment of the present invention.

[0024] The power supply system 1 shown in Fig. 1 is a mobile system that supplies self-generated power to the outside, and supplies power to consumers such as buildings, general homes, etc. As shown in Fig. 1, the power supply system 1 includes, for example, a mobile power supply vehicle 2 and a reverse power flow prevention device 3.

[0025] The mobile power supply vehicle 2 is a mobile private power generation device that is configured by mounting a prime mover, a generator, and auxiliary equipment on a vehicle such as a truck or trailer. The mobile power supply vehicle 2 supplies the power that it generates to consumers via a power supply path 4. The power supply path 4 is for connecting a device on the power transmission side to a device on the power receiving side to realize power transmission, and is realized by, for example, a power distribution line, a transformer, etc.

[0026] FIG. 1 illustrates an example in which the consumer is a general household, but the consumer is not limited to this and may be a building, a factory, or the like.

[0027] The consumer facility 5 as a power receiving device includes, for example, a consumer load 51 and a distributed power supply device 50 that supplies power to the consumer load 51. The consumer load 51 is a device that can be operated by power from an electric device or the like installed in the consumer's facility.

[0028] The distributed power supply device 50 is a private power generation device that supplies the power it generates to a consumer load 51. The distributed power supply device 50 may store the generated power. The distributed power supply device 50 is linked to a power distribution system, and is capable of supplying the power generated or stored in the distributed power supply device 50 to the power distribution system. Examples of the distributed power supply device 50 include a solar power generation device and a home fuel cell.

[0029] In this embodiment, as an example, the distributed power supply device 50 will be described as a photovoltaic power generation device. For example, the photovoltaic power generation device as the distributed power supply device 50 is connected to a wiring system via a photovoltaic power generation power converter (PCS) and a high-frequency removal filter. In addition, a consumer load 51 is connected to the wiring system via a transformer, and three-phase power of the distribution system is stepped down to single-phase power for home use and supplied to the consumer load 51.

[0030] Also, in this embodiment, the mobile power supply vehicle 2 is described as supplying power to multiple consumer equipment 5_1 to 5_n (n is an integer equal to or greater than 2) via the power supply path 4, but there may be only one consumer equipment 5 receiving power supply from the mobile power supply vehicle 2. Furthermore, it is sufficient that at least one of the consumer equipment 5_1 to 5_n receiving power supply from the mobile power supply vehicle 2 is equipped with a distributed power supply unit 50, and it is not necessary that all of the consumer equipment 5_1 to 5_n are equipped with a distributed power supply unit 50.

[0031] The distributed power supply device 50 has an islanding prevention function.

[0032] Here, isolated operation refers to the operation of a distributed power source device such as a solar power generation device supplying power to the power distribution system independently in a state in which the power distribution system is isolated from the power generation equipment of the power company due to an accident or the like.

[0033] Generally, when a power distribution system is disconnected from the power generation facility of a power company and a distributed power supply device is put into an isolated operation state, the balance between the output and the load of the distributed power supply device is lost, causing fluctuations in the voltage and frequency of the power distribution system, which may adversely affect the stable supply of power by the power distribution system. Therefore, the distributed power supply device 50 monitors the voltage and frequency of the power supply path 4 including the distribution line, and when at least one of the voltage and frequency fluctuates, it stops the output of power to the power distribution system (power supply path 4). For example, when the amount of fluctuation in at least one of the voltage and frequency of the power supply path 4 exceeds a preset allowable amount of fluctuation, the distributed power supply device 50 stops the output of power to the power distribution system (power supply path 4).

[0034] In this embodiment, the mobile power supply vehicle 2 is described as supplying power to multiple consumer equipment 5_1 to 5_n (n is an integer equal to or greater than 2) via the power supply path 4, but there may be only one consumer equipment 5 receiving power supply from the mobile power supply vehicle 2. In addition, it is sufficient that at least one of the consumer equipment 5_1 to 5_n receiving power supply from the mobile power supply vehicle 2 is equipped with a distributed power supply unit 50, and it is not necessary that all of the consumer equipment 5_1 to 5_n are equipped with a distributed power supply unit 50.

[0035] The reverse power flow prevention device 3 is a device for preventing power generated or stored by the distributed power supply device 50 from being supplied from the consumer equipment 5_1-5_n to the mobile power supply vehicle 2 (reverse power flow) when power is supplied from the mobile power supply vehicle 2 to the consumer equipment 5_1-5_n. Details of the reverse power flow prevention device 3 will be described later.

[0036] The power supply system 1 supplies power generated by a mobile power supply vehicle 2 to each consumer equipment 5_1 to 5_n via the power supply path 4 in a state in which the connection between a power transmission equipment (e.g., a transformer at a substation or a pole-mounted transformer) that supplies AC power in a three-phase, three-wire system and a power supply path 4 (e.g., a distribution line) is cut off, for example, during a large-scale power outage due to a disaster or during construction and inspection of a distribution line.

[0037] FIG. 2 is a diagram showing a specific configuration of the mobile power supply vehicle 2 and the reverse power flow prevention device 3 in the power supply system 1 according to the embodiment of the present invention.

[0038] 2, the mobile power supply vehicle 2 has, for example, a power generation control device 20, a prime mover 21, a generator 22, and a circuit breaker 23. Power (mechanical energy) generated by the prime mover 21 is transmitted to the generator 22, and the generator 22 generates power using the power. The power generated by the generator 22 is output to the power supply path 4 via the circuit breaker 23.

[0039] The circuit breaker 23 is a device that switches between connection and disconnection between the generator 22 and the power supply path 4. The power generation control device 20 is a device that controls each device of the mobile power supply vehicle 2 and provides overall control of the operation of the mobile power supply vehicle 2.

[0040] The power generation control device 20 is configured to include, for example, a program processing device including various memories and a processor that executes various calculations according to programs stored in the memories, various peripheral circuits controlled by the program processing device, and a user interface such as an operation panel for inputting operations from the user.

[0041] The power generation control device 20 controls the prime mover 21 and the generator 22 to generate power in response to instructions input, for example, via a user interface, and controls the opening and closing of the circuit breaker 23 to switch between outputting and stopping power from the mobile power supply vehicle 2.

[0042] Furthermore, although details will be described later, when a detection signal St is output from the reverse power flow prevention device 3, the power generation control device 20 controls the generator 22 to stop the isolated operation of the distributed power generation devices 50 in each of the customer facilities 5_1 to 5_n.

[0043] As shown in FIG. 2, the reverse power flow prevention device 3 includes a control device 30 , a switch 31 , and a load 32 .

[0044] The switch 31 is a device that switches between connecting and disconnecting (opening) the load 32 to the power supply path 4 that connects the power transmission side device (the mobile power supply vehicle 2) and the power receiving side device (the consumer equipment 5_1 to 5_n). The switch 31 is, for example, a relay. The switch 31 is connected in parallel to the consumer equipment 5_1 to 5_n, which are the power receiving side devices, in the power supply path 4.

[0045] The load 32 is a device for preventing reverse power flow that can be connected to the power supply path 4. The load 32 is connected in series to the switch 31. When the switch 31 is on, the load 32 consumes power supplied from the power supply path 4, thereby preventing the occurrence of reverse power flow.

[0046] The load 32 includes, for example, a resistor 33 and a power conditioning subsystem (PCS) 34 that supplies power from the power supply path 4 to the resistor 33. For example, when the switch 31 is on, the PCS 34 converts the AC voltage from the power supply path 4 into a DC voltage and supplies the DC voltage to the resistor 33.

[0047] The control device 30 monitors the current flowing from the power transmitting side to the power receiving side in the power supply path 4, and controls the switch 31 and the PCS 34. The control device 30 is configured to include, for example, various memories and a program processing device including a processor that executes various calculations according to programs stored in the memories, a current sensor that detects the current, and various peripheral circuits controlled by the program processing device.

[0048] The control device 30 monitors a current i that flows from the mobile power supply vehicle 2 on the power transmission side to the customer equipment 5_1 to 5_n on the power receiving side in the power supply path 4, and prevents the occurrence of a reverse power flow according to the current i.

[0049] 3A and 3B are diagrams for explaining the operation of reverse power flow prevention device 3. FIG.

[0050] 3A and 3B, the horizontal axis represents time and the vertical axis represents current. Reference numerals 301 and 301a represent changes over time in current i that flows from the mobile power supply vehicle 2 on the power transmission side to customer equipment 5_1 to 5_n on the power receiving side in the power supply path 4.

[0051] The control device 30 turns off the switch 31 when a current i flowing in the power supply path 4 from the mobile power supply vehicle 2 on the power transmission side to the customer equipment 5_1 to 5_n on the power reception side is greater than a first threshold value ith1. 3A, for example, the current i is greater than the first threshold value ith1 during the period from time t0 to time t1. Therefore, the control device 30 turns off the switch 31 to disconnect the load 32 (resistor 33) from the power supply path 4. At this time, the control device 30 may stop the operation of the PCS 34.

[0052] Here, the first threshold value ith1 may be stored in advance in the memory within the control device 30, for example, or the user may set a desired value after the power supply system 1 is started up.

[0053] On the other hand, when the current i is lower than the first threshold value ith1, the control device 30 turns on the switch 31. For example, in FIG. 3A, when the current i reaches the first threshold value ith1 at time t1, the control device 30 turns on the switch 31 to connect the load 32 to the power supply path 4. At this time, the control device 30 operates the PCS 34 to convert the AC voltage from the power supply path 4 into a DC voltage and supply it to the resistor 33. As a result, power is supplied not only from the mobile power vehicle 2 to the customer facilities 5_1 to 5_n but also to the load 32, so the current i increases.

[0054] When the state in which the current i exceeds the second threshold value ith2 (<ith1) that is lower than the first threshold value ith1 continues for a predetermined time T1 after the switch is turned on, the control device 30 turns off the switch 31. For example, as shown in FIG. 3A, after the switch 31 is turned on at time t1, the current i exceeds the first threshold value ith1. Then, at time t2 when the state in which the current i exceeds the second threshold value ith2 has elapsed for a predetermined time T1, the control device 30 turns off the switch 31.

[0055] That is, when the current i does not decrease after the switch 31 is turned on, it can be considered that no reverse power flow occurs because the power consumption of the customer load 51 is greater than the generated power of the distributed power generation device 50 on the customer facilities 5_1 to 5_n side. Therefore, in this case, as described above, the switch 31 is turned off to stop the power supply from the mobile power vehicle 2 to the resistor 33.

[0056] Furthermore, when the current i becomes lower than the second threshold value ith2, the control device 30 outputs the detection signal St. For example, as shown in Fig. 3B, even though the switch 31 is turned on at time t1 to start supplying power to the load 32, the current i further decreases and becomes lower than the second threshold value ith2 at time t2, at which point the control device 30 outputs the detection signal St.

[0057] The detection signal St output from the control device 30 is input to the mobile power supply vehicle 2. In the mobile power supply vehicle 2, when power is being supplied to the consumer equipment 5_1 to 5_n, the power generation control device 20 stops the isolated operation of the distributed power supply device 50 if the detection signal St is output from the control device 30 of the reverse power flow prevention device 3.

[0058] As described above, the distributed power supply device 50 installed in each of the customer facilities 5_1 to 5_n has an islanding prevention function. Specifically, the distributed power supply device 50 monitors the voltage and frequency of the power distribution system (power supply path 4), and when at least one of the voltage and the frequency fluctuates, stops outputting power to the power distribution system (power supply path 4).

[0059] Therefore, the power generation control device 20 of the mobile power supply vehicle 2 controls the generator 22 to vary at least one of the magnitude and frequency of the output voltage of the generator 22, thereby stopping the isolated operation of the distributed power supply device 50. For example, when the detection signal St is output from the control device 30, the power generation control device 20 increases the voltage supplied from the generator 22 to the power supply path 4. As a result, the distributed power supply device 50 determines that the fluctuation amount of the voltage of the power supply path 4 has exceeded a preset allowable fluctuation amount, and stops the isolated operation. Also, when the detection signal St is output from the control device 30, the power generation control device 20 varies (raises or lowers) the frequency of the voltage supplied from the generator 22 to the power supply path 4. As a result, the distributed power supply device 50 determines that the fluctuation amount of the frequency of the power supply path 4 has exceeded a preset allowable fluctuation amount, and stops the isolated operation.

[0060] By stopping the isolated operation by the distributed power supply devices 50 of each of the customer facilities 5_1 to 5_n, the occurrence of reverse power flow can be prevented.

[0061] Next, the flow of operations performed by the power supply system 1 will be described. FIG. 4 is a flowchart showing an example of the flow of operations related to power supply by the power supply system 1.

[0062] For example, when power is supplied from the mobile power supply vehicle 2 to the power supply path 4 in response to an input operation by a user, the control device 30 of the reverse power flow prevention device 3 turns off the switch 31 (step S1). This causes the load 32 (resistor 33) of the reverse power flow prevention device 3 to be disconnected from the power supply path 4.

[0063] Next, the mobile power supply vehicle 2 starts supplying power (step S2). Specifically, in the mobile power supply vehicle 2, the power generation control device 20 starts up the prime mover 21 and the generator 22 and turns on the circuit breaker 23 to start supplying power to the power supply path 4. As a result, power is supplied from the mobile power supply vehicle 2 to each of the customer facilities 5_1 to 5_n via the power supply path 4.

[0064] When the mobile power supply vehicle 2 is supplying power, the control device 30 of the reverse power flow prevention device 3 monitors the current i flowing from the mobile power supply vehicle 2 side to each of the customer facilities 5_1 to 5_n side (step S3).

[0065] When monitoring the current i, the control device 30 of the reverse power flow prevention device 3 determines whether the current i is equal to or smaller than a first threshold value ith1 (step S4). When the current i is greater than the first threshold value ith1 (step S4: NO), the control device 30 continues to turn off the switch 31 (step S5).

[0066] On the other hand, when the current i is equal to or less than the first threshold value ith1 (step S4: YES), the control device 30 turns on the switch 31 (step S6). As a result, since the load 32 of the reverse power flow prevention device 3 is connected to the power supply path 4 via the switch 31, the power of the mobile power vehicle 2 is also supplied to the load 32, and the current i increases.

[0067] Next, the control device 30 of the reverse power flow prevention device 3 determines whether the current i is equal to or less than the second threshold value ith2 (<ith1) (step S7). When the current i is greater than the second threshold value ith2, it is determined whether a predetermined time T1 has elapsed since the switch 31 was turned on in step S6 (step S8). If the predetermined time T1 has not elapsed (step S8: NO), the control device 30 returns to step S7.

[0068] On the other hand, when the predetermined time T1 has elapsed (step S8: YES), since it is considered that no reverse power flow occurs, the control device 30 turns off the switch 31 (step S9). As a result, again, the load 32 (resistor 33) of the reverse power flow prevention device 3 is disconnected from the power supply path 4.

[0069] On the other hand, in step S7, when the current i is equal to or less than the second threshold value ith2 (step S7: YES), the control device 30 of the reverse power flow prevention device 3 outputs a detection signal St (step S10).

[0070] The power generation control device 20 of the mobile power vehicle 2 stops the independent operation of the distributed power supply device 50 in each consumer facility 5_1 to 5_n according to the detection signal St output from the reverse power flow prevention device 3 (step S11). Specifically, as described above, in the mobile power vehicle 2, the power generation control device 20 changes at least one of the magnitude of the output voltage and the frequency of the generator 22 so as to exceed at least one of the allowable variation amounts of the voltage and the frequency related to the independent operation stop function preset in the distributed power supply device 50.

[0071] As a result, the isolated operation of the distributed power supply apparatus 50 in each of the customer facilities 5_1 to 5_n is stopped, and the power supply from the distributed power supply apparatus 50 to the power supply path 4 is stopped (step S12).

[0072] After step S5, step S9, or step S12, the power generation control device 20 in the mobile power supply vehicle 2 determines whether or not an instruction to stop the power supply by the mobile power supply vehicle 2 has been given (step S13). For example, when an instruction to stop the power supply is given by an input operation by the user, the power generation control device 20 turns off the circuit breaker 23 and stops the operation of the prime mover 21 and the generator 22, thereby stopping the power supply to the power supply path 4.

[0073] On the other hand, if an instruction to stop the power supply from the mobile power supply vehicle 2 has not been received, the power generation control device 20 continues the power supply from the mobile power supply vehicle 2 (step S2).

[0074] As described above, the reverse power flow prevention device 3 according to this embodiment includes the switch 31 connected in parallel with the power receiving side device (consumer equipment 5_1 to 5_n) in the power supply path 4, the load 32 for preventing reverse power flow connected in series to the switch 31, and the control device 30. As described above, the control device 30 monitors the current i flowing from the power transmitting side to the power receiving side in the power supply path 4, turns off the switch 31 when the current i is greater than the first threshold value ith1, and turns on the switch 31 when the current i is lower than the first threshold value ith1.

[0075] According to this, the reverse power flow prevention device 3 connects the resistor 33 to the generator 22 of the mobile power supply vehicle 2 when the current i flowing from the power transmitting side to the power receiving side in the power supply path 4 falls below a predetermined magnitude, so that it is possible to prevent the occurrence of reverse power flow even if the power consumption by the consumer load 51 decreases when power is being supplied from the mobile power supply vehicle 2 to the consumer equipment 5_1 to 5_n. Also, the power consumption by the resistor 33 can be reduced compared to when the resistor 33 is constantly connected. In other words, the reverse power flow prevention device 3 of this embodiment makes it possible to reduce the power consumption in the resistor while preventing the generator of the mobile power supply vehicle from being stopped due to the occurrence of reverse power flow.

[0076] Furthermore, in the reverse power flow prevention device 3, as described above, the control device 30 turns off the switch 31 if the state in which the current i exceeds the second threshold ith2, which is lower than the first threshold ith1, continues for a predetermined time T1 after the switch 31 is turned on. According to this, even if the current i falls below the first threshold value ith1, when there is a high possibility that reverse power flow will not occur, the resistor 33 is disconnected from the power supply path 4, so that it is possible to more reliably prevent reverse power flow while suppressing power consumption by the resistor 33.

[0077] Furthermore, in the reverse power flow prevention device 3, as described above, the control device 30 outputs the detection signal St when the current i becomes lower than the second threshold value ith2 after turning on the switch 31. This makes it possible to notify the outside that there is a high possibility of reverse power flow occurring when power is being supplied from the mobile power supply vehicle 2 to the customer facilities 5_1 to 5_n.

[0078] Furthermore, in a power supply system 1 equipped with a reverse power flow prevention device 3 of this embodiment and a mobile power supply vehicle 2, when the mobile power supply vehicle 2 is supplying power to consumer equipment 5_1 to 5_2, if a detection signal St is output from the control device 30 of the reverse power flow prevention device 3, the mobile power supply vehicle 2 stops the independent operation of the distributed power supply devices 50 in the consumer equipment 5_1 to 5_n. According to this, if there is still a risk of reverse power flow occurring due to the capacity limit of resistor 33 of the reverse power flow prevention device 3 (exceeding the rated power consumption) even if resistor 33 is connected to the power supply path 4, the power supply from the distributed power supply device 50 is stopped, thereby reliably preventing the occurrence of reverse power flow.

[0079] Furthermore, in the power supply system 1, as described above, when a detection signal St is output from the control device 30 of the reverse power flow prevention device 3, the mobile power supply vehicle 2 increases the voltage supplied to the power supply path 4. This makes it possible to easily stop the isolated operation of the distributed power supply devices 50 without transmitting a special instruction signal to the distributed power supply devices 50 in each of the customer facilities 5_1 to 5_n.

[0080] Furthermore, in the power supply system 1, as described above, when a detection signal St is output from the control device 30 of the reverse power flow prevention device 3, the mobile power supply vehicle 2 varies the frequency of the voltage supplied to the power supply path 4. This makes it possible to easily stop the isolated operation of the distributed power supply device 50, similar to the case where the voltage supplied to the power supply path 4 is increased.

[0081] <<Extension of the embodiment>> The invention made by the present inventors has been specifically described above based on an embodiment, but it goes without saying that the invention is not limited thereto and can be modified in various ways without departing from the spirit of the invention.

[0082] For example, in the above embodiment, the resistor 33 is used as the load 32, but the load 32 is not limited to this and may be anything that can absorb power. For example, a secondary battery (storage battery) may be used as the load 32. In this case, power can be stored in the secondary battery, making it possible to reduce unnecessary power consumption.

[0083] In addition, in the above embodiment, a case has been described in which the power transmission device is a mobile power supply vehicle 2, but the power transmission device may be any device capable of supplying power to consumer equipment 5_1 to 5_n, and is not limited to the mobile power supply vehicle 2.

[0084] Furthermore, the control device 30 of the reverse power flow prevention device 3 may monitor the current flowing through the load 32. In this way, the control device 30 can more accurately monitor the state of power supply to the consumers by calculating the current flowing through the consumer facilities 5_1 to 5_n from the current flowing through the load 32 and the current i.

[0085] In addition, the above-mentioned flowchart shows an example for explaining the operation, and is not limited to this. That is, the steps shown in each figure of the flowchart are specific examples, and are not limited to this flow. For example, the order of some processes may be changed, other processes may be inserted between each process, and some processes may be performed in parallel. [Explanation of symbols]

[0086] 1...power supply system, 2...mobile power supply vehicle, 3...reverse power flow prevention device, 4...power supply path, 5_1 to 5_n...consumer equipment, 20...power generation control device, 21...prime mover, 22...generator, 23...circuit breaker, 30...control device, 31...switch, 32...load, 33...resistance, 34...PCS, 50...distributed power supply device, 51...consumer load, St...detection signal.

Claims

1. A mobile power supply vehicle that supplies power to consumer equipment including a distributed power supply device connected to a power distribution system via a power supply path; A reverse power flow prevention device, The reverse power flow prevention device includes: a switch connected in parallel to the customer facility in the power supply path; A load for preventing reverse power flow connected in series to the switch; a control device that monitors a current flowing from the mobile power supply vehicle side to the consumer equipment side in the power supply path, turns off the switch when the current is greater than a first threshold value, and turns on the switch when the current is lower than the first threshold value. Power supply system.

2. 2. The power supply system according to claim 1, The control device turns off the switch when a state in which the current exceeds a second threshold value lower than the first threshold value continues for a predetermined time after the switch is turned on. Power supply system.

3. 3. The power supply system according to claim 2, The control device outputs a detection signal when the current becomes lower than the second threshold. Power supply system.

4. 4. The power supply system according to claim 3, When the detection signal is output from the control device while the mobile power supply vehicle is supplying power to the customer facility, the mobile power supply vehicle stops the isolated operation of the distributed power supply device. Power supply system.

5. 5. The power supply system according to claim 4, The mobile power supply vehicle increases the voltage supplied to the power supply path to stop the independent operation of the distributed power supply device. Power supply system.

6. 5. The power supply system according to claim 4, The mobile power supply vehicle fluctuates the frequency of the voltage supplied to the power supply path to stop the independent operation of the distributed power supply device. Power supply system.

7. A method of supplying power to a consumer facility by a power supply system including a mobile power supply vehicle, a load for preventing reverse power flow connectable in parallel to the consumer facility on a power supply path connecting the mobile power supply vehicle to the consumer facility, the load including a distributed power supply device linked to a power distribution system, and a control device for controlling connection of the load to the power supply path, comprising: a first step of the mobile power supply vehicle supplying power to the power supply path; a second step in which the control device monitors a current flowing through the power supply path from the mobile power supply vehicle side to the consumer equipment side; a third step of the control device disconnecting the load from the power supply path when the current is higher than a first threshold; and a fourth step of the control device connecting the load to the power supply path when the current becomes lower than the first threshold. Power supply method.

8. 8. The power supply method according to claim 7, The method further includes a fifth step of, when a state in which the current exceeds a second threshold value lower than the first threshold value continues for a predetermined time after the fourth step, the control device disconnects the load from the power supply path. Power supply method.

9. 9. The power supply method according to claim 8, a sixth step of the control device outputting a detection signal when the current becomes lower than the second threshold value after the fourth step; and a seventh step of causing the mobile power supply vehicle to stop independent operation of the distributed power supply system when the detection signal is output from the control device. Power supply method.

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