Power supply system and power supply method

Abstract

To efficiently drive a generator while maximizing the use of an inverter-based power supply in a power supply network.SOLUTION: In a power supply network 1, at least one of a plurality of inverter-based power supply devices 5 and 6 having a grid connection protection relay has a voltage or frequency that serves as a reference for whether to operate the grid connection protection relay, which is set to a value different from setting values Vs2 and Vs3 of another power supply devices. In the power supply network 1, a power supply control device 3 includes a current value acquiring unit 31 that acquires a measured value of a current i flowing from a power generation device 2 to a power receiving side in a power supply path 4, and a control unit 30 that controls the power generation device 2 such that the voltage or frequency of the power supply path 4 exceeds a range determined by the setting value in stages according to changes in the measured value of the current i.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a power supply system and a power supply method, and more particularly to a power supply system in a small-scale power supply network such as a microgrid.

Background Art

[0002] In recent years, a microgrid has attracted attention as a small-scale power supply network that supplies power from a plurality of small-scale power generation facilities to a plurality of consumers in a certain area. A microgrid is a power supply system that aims for on-site power consumption without relying on the power supply of a large-scale power plant by combining a plurality of power sources and controlling the power supply to consumers within a limited area.

[0003] Generally, a microgrid has, for example, a generator (e.g., a diesel generator (DG)) as a main power source and an inverter-based power supply device, and supplies power from these power supply devices to a consumer load.

[0004] Here, an inverter-based power supply device (IBR: Inver Based Resources) is a power supply device that outputs generated power through a built-in inverter, and examples thereof include a photovoltaic apparatus and a wind power generation device.

[0005] An inverter-based power supply device such as a photovoltaic apparatus in a microgrid is installed within the premises of a consumer as consumer equipment, supplies power to the consumer load, and is connected to the distribution system within the microgrid. When supplying power from a generator to a consumer where an inverter-based power supply device is installed, if power exceeding the demand on the consumer side is generated from the inverter-based power supply device, a reverse power flow occurs from the photovoltaic apparatus side to the generator side.

[0006] When reverse power flow occurs, the generator will stop. Once the generator stops, it takes time to restart the generator, and a power outage may occur before the generator resumes operation. Therefore, in a microgrid, it is very important not to stop the generator.

[0007] Conventionally, as a technique for preventing reverse power flow to a generator, in a mobile power supply vehicle equipped with a generator, a method of connecting a resistor in parallel to a customer load that receives power supply from the generator is known (see, for example, Patent Document 1). According to this method, since power is always consumed by the resistor, 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 from stopping.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] As in the technique disclosed in Patent Document 1 above, by connecting a resistor to the generator in a microgrid, even when the demand on the customer side decreases, it is possible to avoid the occurrence of reverse power flow from the inverter-based power supply device side such as a solar power generation device to the generator side.

[0010] However, when a resistor is constantly connected to the generator, power is constantly consumed in the resistor, so the fuel of the prime mover for driving the generator is wasted, the operating time of the generator is shortened, and the efficiency of the generator is reduced. Also, when the demand on the customer side decreases, by stopping all inverter-based power supply devices, it is possible to prevent the occurrence of reverse power flow. However, not only does the fuel consumption of the generator increase significantly, but the disadvantages of power selling businesses such as solar power generation devices also increase.

[0011] The present invention has been made in view of the above-described problems, and in a power supply network in which a generator and a plurality of inverter-based power supply devices are connected to a power distribution system, an object thereof is to efficiently drive the generator while maximizing the utilization of the inverter-based power supply devices.

Means for Solving the Problems

[0012] A power supply control device according to a typical embodiment of the present invention is a power supply control device for controlling the supply of power to a power supply path in a power supply network including a power supply path for supplying power to a customer load, a power generation device that generates power based on mechanical energy and supplies the power to the power supply path, and a plurality of inverter-based power supply devices having a system connection protection relay and connected to the power supply path, wherein at least one of the plurality of inverter-based power supply devices has a setting value of a voltage or frequency serving as a criterion for operating or not operating the system connection protection relay set to a value different from the setting value of the other power supply devices, the system connection protection relay enables the output of power from the power supply device when the voltage or frequency of the power supply path is within a range defined by the setting value, stops the output of power from the power supply device when the voltage or frequency of the power supply path exceeds the range defined by the setting value, and the power supply control device includes a current value acquisition unit that acquires a measured value of a current flowing on the power receiving side of the power supply path from the power generation device, and a control unit that controls the power generation device so that the voltage or frequency of the power supply path gradually exceeds the range defined by the setting value in response to a change in the measured value of the current.

Effects of the Invention

[0013] According to the power supply system of the present invention, in a power supply network in which a generator and a plurality of inverter-based power supply devices are connected to a power distribution system, it is possible to efficiently drive the generator while maximizing the utilization of the inverter-based power supply devices.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0015] 1. Outline of the Embodiment First, an outline of typical embodiments of the invention disclosed in the present application will be described. In the following description, as an example, the reference numerals in the drawings corresponding to the components of the invention are described with parentheses.

[0016] 〔1〕The power supply control device (3, 3A) according to a representative embodiment of the present invention is a power supply network (1, 1A) having a power supply path (4) for supplying power to a customer load, a power generation device (2) that generates power based on mechanical energy and supplies the power to the power supply path, and a plurality of inverter-based power supply devices (5, 6) having a system connection protection relay (53) and connected to the power supply path. The power supply control device controls the supply of power to the power supply path, wherein at least one of the plurality of inverter-based power supply devices has a setting value (Vs1) of voltage or frequency that serves as a criterion for operating or not operating the system connection protection relay set to a value different from the setting values (Vs2, Vs3) of the other power supply devices. The system connection protection relay enables the output of power from the power supply device when the voltage or frequency of the power supply path is within the range defined by the setting value, and stops the output of power from the power supply device when the voltage or frequency of the power supply path exceeds the range defined by the setting value. The power supply control device includes a current value acquisition unit (31) that acquires a measured value of a current (i) flowing on the power receiving side from the power generation device to the power supply path, and a control unit (30, 30A) that controls the power generation device so that the voltage or frequency of the power supply path gradually exceeds the range defined by the setting value in response to a change in the measured value of the current.

[0017] 〔2〕In the power supply control device according to the above 〔1〕, the plurality of inverter-based power supply devices are divided into a plurality of groups (GR1 to GR3). For the power supply device (6) of the first group (GR1) among the plurality of groups, a first value (Vs1) is set as the set value of the voltage or frequency. For the power supply devices (5) of the groups (GR2, GR3) other than the first group, values (Vs2, Vs3) different from the first value are set as the set values of the voltage or frequency. When the measured value of the current is greater than a first threshold value (ith1), the control unit controls the power generation device so that the voltage (Vo) or frequency of the power supply path is within the range defined by the first value (Vo < Vs1). When the measured value of the current drops below the first threshold value, the control unit may control the power generation device so that the voltage (Vo) or frequency of the power supply path exceeds the range defined by the first value and is within the range defined by the second value (Vs1 ≤ Vo < Vs2).

[0018] 〔3〕In the power supply control device according to the above 〔2〕, for the power supply device (5) of the second group (GR2) among the groups other than the first group, the second value (Vs2) is set as the set value of the voltage or frequency. For the power supply devices (5) belonging to the groups (GR3) other than the first group and the second group, a value (Vs3) different from the first value and the second value is set as the set value of the voltage or frequency. When the current drops below a second threshold value, the control unit may control the power generation device so that the voltage (Vo) or frequency of the power supply path exceeds the ranges defined by the first value and the second value and is within the range defined by the third value (Vs2 ≤ Vo < Vs3).

[0019] 〔4〕In the power supply control device according to the above 〔2〕 or 〔3〕, the set value of the power supply device with the largest power generation amount among the plurality of inverter-based power supply devices may be set to the first value.

[0020] 〔5〕In the power supply control device (3A) according to any one of the above (1) to (4), the power supply control device further includes a setting value setting unit (32A) for setting the setting values of the plurality of inverter-based power supply devices, and the setting value setting unit changes the setting values of the plurality of inverter-based power supply devices so that the power supply device that stops power output switches every fixed time (T1) when the system interconnection protection relay operates.

[0021] 〔6〕In the power supply control device (3) according to any one of the above (1) to (4), the power supply control device further includes a setting value setting unit (32) for setting the setting values of the plurality of inverter-based power supply devices, and the setting value setting unit may set the setting values of the plurality of inverter-based power supply devices such that the values become smaller as the power generation amount of the power supply device becomes smaller.

[0022] 〔7〕A power supply network (1, 1A) according to a typical embodiment of the present invention includes the power supply control device (3, 3A) according to any one of the above (1) to (6), the power supply path (4), the plurality of inverter-based power supply devices (5, 6) connected to the power supply path, and the customer load (7) connected to the power supply path.

[0023] 〔8〕The power supply control method according to a representative embodiment of the present invention is a power supply control method for controlling the supply of power to a customer load (7) in a power supply network (1, 1A) including a power supply path (4) for supplying power to the customer load, a power generation device (2) that generates power based on mechanical energy and supplies the power to the power supply path, and a plurality of inverter-based power supply devices (5, 6) having a system connection protection relay (53) and connected to the power supply path. In the method, at least one of the plurality of inverter-based power supply devices has a setting value (Vs1) of voltage or frequency that serves as a criterion for operating or not operating the system connection protection relay set to a value different from the setting values (Vs2, Vs3) of the other power supply devices. The system connection protection relay enables the output of power from the power supply device when the voltage or frequency of the power supply path is within the range defined by the setting value, and stops the output of power from the power supply device when the voltage or frequency of the power supply path exceeds the range defined by the setting value. The method includes a first step (S3, S5, S7) of acquiring a measured value of a current (i) flowing on the power receiving side of the power supply path from the power generation device, and a step (S4, S6, S8) of controlling the power generation device so that the voltage or frequency of the power supply path gradually exceeds the range defined by the setting value in response to a change in the measured value of the current.

[0024] 2. Specific Example of Embodiment Hereinafter, specific examples of embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals are assigned to the common components in each embodiment, and repeated descriptions are omitted.

[0025] ≪Embodiment 1≫ FIG. 1 is a diagram showing the configuration of a power supply network 1 including a power supply control device 3 according to Embodiment 1 of the present invention.

[0026] The power supply network 1 shown in FIG. 1 is a small-scale network that supplies power to a plurality of customer loads 7 from a plurality of small-scale power generation facilities, for example, a microgrid.

[0027] The power supply network 1 includes a power generation device 2, a power supply control device 3, and a plurality of inverter-based power supply devices 5_1 to 5_n (n is an integer of 2 or more), 6.

[0028] The power generation device 2 is a device that generates power based on mechanical energy. The power generation device 2 is, for example, a diesel generator (DG). The power generation device 2 supplies the power generated by itself to customers via the power supply path 4. Here, customers include, for example, not only ordinary households but also buildings, factories, etc. The power supply path 4 is for connecting a power transmission-side device and a power reception-side device of power to realize power transmission, and is realized by, for example, a distribution line, a transformer, or the like.

[0029] Facilities in customers include, for example, a customer load 7 and an inverter-based power supply device 5 that supplies power to the customer load 7. The customer load 7 is a device that can be operated by the power of electrical equipment installed in the customer's facility.

[0030] The inverter-based power supply device 5 is a self-generation device that supplies the power generated by itself to the customer load 7. The power supply device 5 may store the generated power. The power supply device 5 is linked to the power distribution system and can supply the power generated or stored in the power supply device 5 to the power distribution system. Examples of the power supply device 5 include a solar power generation device and a household fuel cell.

[0031] In this embodiment, as an example, the power supply device 5 is described as a photovoltaic power generation device (PV). For example, the photovoltaic power generation device as the power supply device 5 is connected to the wiring system via a power conversion device for photovoltaic power generation (PCS) 52 with a built-in inverter and a high-frequency removal filter (not shown). Further, the customer load 7 is connected to the wiring system via a transformer, and the three-phase power of the power distribution system is stepped down to single-phase for the home and supplied to the customer load 7.

[0032] The inverter-based power supply device 6 is, for example, a large-scale photovoltaic power generation device (megasolar) having a larger power generation capacity than the above-described power supply device 5. The power supply device 6 is connected to the wiring system via a power conversion device for photovoltaic power generation (PCS) 52 with a built-in inverter and a high-frequency removal filter, similarly to the power supply device 5.

[0033] In addition to the above-described large-scale photovoltaic power generation device, a wind power generation device, a biomass power generation device, or the like may be installed as the inverter-based power supply device connected to the power supply path 4.

[0034] The power supply devices 5 and 6 are provided with a system connection protection relay 53. The system connection protection relay 53 is, for example, built in the PCS 52.

[0035] The system connection protection relay 53 is a relay for protecting systems such as the power supply path 4. The system connection protection relay 53 stops when the voltage or frequency of the power supply path 4 is within the range determined by a preset allowable value (setting value), and operates when the voltage or frequency of the power supply path 4 exceeds the range determined by the setting value.

[0036] Here, the setting value is the value of the voltage or frequency that serves as a criterion for operating or not operating the system connection protection relay 53.

[0037] Specifically, the system connection protection relay 53 enables the connection of the power supply devices 5 and 6 to the system when the voltage or frequency of the power supply path 4 is within the range defined by the setting value. That is, the system connection protection relay 53 enables the output of power from the power supply devices 5 and 6 (the output of power to the power supply path 4 and the consumer load 7).

[0038] On the other hand, when the voltage or frequency of the power supply path 4 exceeds the range defined by the setting value, the system connection protection relay 53 stops the connection of the power supply devices 5 and 6 to the system. That is, the system connection protection relay 53 stops the output of power from the power supply devices 5 and 6 (the output of power to the power supply path 4 and the consumer load 7).

[0039] The system connection protection relay 53 includes, for example, an overvoltage relay (OVR), an undervoltage relay (UVR), an overfrequency relay (OFR), and an underfrequency relay (UFR).

[0040] The overvoltage relay (OVR) operates when the voltage of the power supply path 4 exceeds the setting value (for example, 107 V), and stops the supply of power from the power supply devices 5 and 6 to the distribution system (power supply path 4) and the consumer load 7.

[0041] The undervoltage relay (UVR) operates when the voltage of the power supply path 4 drops below the setting value (for example, 95 V), and stops the supply of power from the power supply devices 5 and 6 to the distribution system (power supply path 4) and the consumer load 7.

[0042] The overfrequency relay (OFR) operates when the frequency of the power supply path 4 exceeds the setting value (for example, 51 Hz), and stops the supply of power from the power supply devices 5 and 6 to the distribution system (power supply path 4) and the consumer load 7.

[0043] The underfrequency relay (UFR) operates when the frequency of the power supply path 4 drops below the setting value (for example, 48.5 Hz), and stops the supply of power from the power supply devices 5 and 6 to the distribution system (power supply path 4) and the consumer load 7.

[0044] The power supply control device 3 is a centralized management device that monitors the power supply and demand status of the power supply network 1 and comprehensively controls the entire power supply network 1 so that a stable power supply is achieved. The power supply control device 3 can communicate with the power generation device 2 and the power supply devices 5 and 6 via a wide-area communication network 8 typified by the Internet, for example.

[0045] FIG. 2 is a diagram showing a specific configuration of the power supply control device 3 according to Embodiment 1.

[0046] As described above, the power generation device 2 is a diesel generator, and as shown in FIG. 2, for example, it has a power generation control device 20, a prime mover 21, a generator 22, and a circuit breaker 23. In the power generation device 2, the power (mechanical energy) generated by the prime mover 21 is transmitted to the generator 22, and the generator 22 generates electricity by that power. The electricity generated by the generator 22 is output to the power supply path 4 via the circuit breaker 23.

[0047] The circuit breaker 23 is a device that switches between connecting and disconnecting the generator 22 and the power supply path 4. The power generation control device 20 is a device that controls each device of the power generation device 2 and comprehensively controls the operation of the power generation device 2.

[0048] The power generation control device 20 includes, for example, a program processing device including a processor that executes various operations according to various memories and 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.

[0049] The power generation control device 20 controls the prime mover 21 and the generator 22 to execute power generation in response to an instruction input via the user interface, for example, and controls the opening and closing of the circuit breaker 23 to switch between power output and stop from the power generation device 2.

[0050] Further, although details will be described later, the power generation control device 20 controls the generator 22 in accordance with the instruction signal Sd from the power supply control device 3 to change the magnitude or frequency of the voltage output from the generator 22 (the voltage Vo of the power supply path 4).

[0051] The power supply control device 3 is a device that controls the supply of power in the power supply network 1 in the power supply path 4. Specifically, the power supply control device 3 controls the power generation device 2 to change the magnitude or frequency of the voltage Vo of the power supply path 4, thereby operating the system interconnection protection relay 53 of the power supply devices 5 and 6, and performing reverse power flow prevention control to selectively stop the output of power from the power supply devices 5 and 6 to the power supply path 4 and the consumer load 51.

[0052] As shown in FIG. 2, the power supply control device 3 includes a control unit 30, a current value acquisition unit 31, a setting value setting unit 32, and a storage unit 33 as functional blocks for performing reverse power flow prevention control. The power supply control device 3 is realized by, for example, an information processing device such as a server. Further, the control unit 30, the current value acquisition unit 31, the setting value setting unit 32, and the storage unit 33 as functional blocks are realized by, for example, program processing by the above-described information processing device.

[0053] The current value acquisition unit 31 is a functional unit that acquires a measured value of the current i flowing from the power transmission side (power generation device 2) to the consumer side (consumer load 7) in the power supply path 4.

[0054] For example, the current i is measured by an ammeter installed in the power supply path 4 or an ammeter in the power generation device 2. The current value acquisition unit 31 acquires the measured value of the current i from these ammeters. By measuring the current i, it is possible to estimate the power consumed by the consumer load 7 (power demand) that is covered by the power generation device 2 (supply power of the power generation device 2).

[0055] The setting value setting unit 32 is a functional unit that sets the setting values of the plurality of inverter-based power supply devices 5 and 6.

[0056] In the power supply network 1, the setting value of at least one of the plurality of inverter-based power supply devices 5 and 6 is set to a value different from the setting values of the other power supply devices. Specifically, the plurality of inverter-based power supply devices 5 and 6 are divided into a plurality of groups, and different setting values are set for each of these groups.

[0057] In the following description, the case where the setting value of the overvoltage relay (OVR) among the system connection protection relays 53 is set to a different value for each group will be taken as an example for explanation.

[0058] For example, as shown in FIG. 2, in the power supply network 1, the power supply devices 5 and 6 are divided into three groups GR1, GR2, and GR3. For example, the power supply device 6 as a large-scale solar power generation device is included in the group GR1. The group GR2 includes m (m is an integer smaller than n) of the n (n is an integer of 2 or more) power supply devices 5 connected to the power supply path 4. The group GR3 includes (n - m) of the n power supply devices 5.

[0059] The setting value setting unit 32 accesses each of the power supply devices 5 and 6 via the communication network 8 and sets different setting values for each of the groups GR1 to GR3. For example, the first setting value Vs1 (for example, 107 V) is set for the power supply device 6 included in the group GR1, the second setting value Vs2 (for example, 108 V) is set for the m power supply devices 5 included in the group GR2, and the third setting value Vs3 (for example, 109 V) is set for the (n - m) power supply devices 5 included in the group GR3. The information on the setting values to be set for each of the groups GR1 to GR3 is stored in the storage unit 33 in advance, for example, and the setting value setting unit 32 sets the setting values for the power supply devices 5 and 6 of each of the groups GR1 to GR3 based on the setting value information read from the storage unit 33.

[0060] The control unit 30 is a functional unit that performs overall control of the power supply control device 3. The control unit 30 monitors the power supply and demand state of the power supply network 1 by controlling the current value acquisition unit 31, the setting value setting unit 32, and the storage unit 33. Specifically, the control unit 30 monitors the power supply and demand state of the power supply network 1 by comparing the measured value of the current i flowing through the power supply path 4 with the threshold values ith1, ith2, and ith3. The information of the threshold values ith1, ith2, and ith3 is stored in the storage unit 33 in advance, for example, and the control unit 30 monitors the current i based on the information stored in the storage unit 33.

[0061] In the following description, the case where ith1 < ith2 < ith3 is exemplified, but it is not limited to this, and ith1 > ith2 > ith3 or ith1 = ith2 = ith3 may also be used.

[0062] Furthermore, the control unit 30 selectively stops the power output from the power supply devices 5 and 6 to the power supply path 4 and the consumer load 51 according to the measured value of the current i. Specifically, the control unit 30 controls the power generation device 2 so that the voltage Vo or the frequency of the power supply path 4 changes step by step based on the comparison result between the measured value of the current i and the threshold values ith1, ith2, and ith3. Hereinafter, the control method of the power generation device 2 by the control unit 30 will be described in detail.

[0063] FIG. 3 is a diagram showing the relationship between the voltage Vo of the power supply path 4 and the operating states of the power supply devices 5 and 6 in each group GR1 to GR3.

[0064] In FIG. 3, O represents a state where the system connection protection relay 53 is stopped, that is, a state where the power output from the power supply devices 5 and 6 to the power supply path 4 and the consumer load 51 is possible. X represents a state where the system connection protection relay 53 is operating, that is, a state where the power output from the power supply devices 5 and 6 to the power supply path 4 and the consumer load 51 is stopped.

[0065] When the measured value of the current i is greater than the first threshold value ith1, the control unit 30 controls the power generation device 2 so that the voltage Vo of the power supply path 4 is within the range defined by the first setting value Vs1, that is, becomes smaller than the first setting value Vs1 (Vo < Vs1). In this case, as shown in FIG. 3, the power supply devices 5 and 6 of all the groups GR1 to GR3 become operable.

[0066] Also, when the measured value of the current i drops below the first threshold value ith1, the control unit 30 controls the power generation device 2 so that the voltage Vo of the power supply path 4 exceeds the range defined by the first setting value Vs1 and is within the range defined by the second setting value Vs2. Specifically, the control unit 30 controls the power generation device 2 so that the voltage Vo of the power supply path 4 is equal to or greater than the first setting value Vs1 and less than the second setting value Vs2 (Vs1 ≤ Vo < Vs2). In this case, as shown in FIG. 3, the power supply device 6 of the group GR1 stops, and the power supply devices 5 of the groups GR2 and GR3 operate.

[0067] Also, when the current i drops below the second threshold value ith2 after the voltage Vo of the power supply path 4 has become greater than the first setting value Vs1, the control unit 30 controls the power generation device 2 so that the voltage Vo of the power supply path 4 exceeds the range defined by the second setting value Vs2 and is within the range defined by the third setting value Vs3. Specifically, the control unit 30 controls the power generation device 2 so that the voltage Vo of the power supply path 4 is equal to or greater than the second setting value Vs2 and less than the third setting value Vs3 (Vs2 ≤ Vo < Vs3). In this case, as shown in FIG. 3, in addition to the group GR1, the power supply device 5 of the group GR2 stops, and the power supply device 5 of the group GR3 operates.

[0068] Furthermore, when the current i drops below the third threshold value ith3 after the voltage Vo of the power supply path 4 becomes greater than the second set value Vs2, the control unit 30 controls the power generation device 2 so that the voltage Vo of the power supply path 4 exceeds the range defined by the third set value Vs3. Specifically, the control unit 30 controls the power generation device 2 so that the voltage Vo of the power supply path 4 becomes equal to or greater than the third set value Vs3 (Vs3 ≦ VO). In this case, as shown in FIG. 3, in addition to the groups GR1 and GR2, the power supply devices 5 of the group GR3 stop, so the operations of all the power supply devices 5 and 6 stop.

[0069] FIG. 4 is a diagram showing the time change of the current i when reverse power flow prevention control is performed. In FIG. 4, the vertical axis represents the current, and the horizontal axis represents the time. Also, the reference numeral 401 represents the change over time of the current i.

[0070] At time t0 in FIG. 4, it is assumed that the measured value of the current i is greater than the first threshold value ith1 and sufficient power is supplied from the power generation device 2 to the power supply path 4. In this case, the control unit 30 controls the power generation device 2 so that the voltage Vo of the power supply path 4 becomes a value smaller than the first set value Vs1 (for example, the reference value Vb = 106.5 V). As a result, as shown in FIG. 3, the power supply devices 5 and 6 of all the groups GR1 to GR3 connected to the power supply path 4 become operable.

[0071] Thereafter, due to a decrease in the power consumption of the customer load 7, the current i decreases, and it is assumed that the current i becomes equal to or less than the first threshold value ith1 at time t1. In this case, the control unit 30 of the power supply control device 3 instructs the power generation device 2 via the instruction signal Sd so that the voltage Vo of the power supply path 4 becomes, for example, the reference value Vb + 1 V (= 106.5 V + 1 V = 107.5 V). As a result, the operation of the power supply device 6 of the group GR1 set to the first set value Vs1 (= 107 V) stops, so the supply power of the power generation device 2 increases in place of the power supply device 6 of the group GR1, and the current i starts to increase.

[0072] Thereafter, due to a further decrease in the power consumption of the customer load 7, the current i decreases, and it is assumed that at time t2, the current i becomes equal to or less than the second threshold value ith2. In this case, the control unit 30 instructs the power generation device 2 via the instruction signal Sd so that the voltage Vo of the power supply path 4 becomes, for example, the reference value Vb + 2V (= 106.5V + 2V = 108.5V). As a result, in addition to the group GR1, the operation of the power supply device 5 of the group GR2 set to the second setting value Vs2 (= 108V) stops, and the power supply from the power generation device 2 increases instead of the power supply device 5 of the group GR2, and the current i increases again.

[0073] Thereafter, due to a further decrease in the power consumption of the customer load 7, the current i decreases, and it is assumed that at time t3, the current i becomes equal to or less than the third threshold value ith3. In this case, the control unit 30 instructs the power generation device 2 via the instruction signal Sd so that the voltage of the power supply path 4 becomes the reference value Vb + 3V (= 106.5V + 3V = 109.5V). As a result, in addition to the groups GR1 and GR2, the operation of the power supply device 5 of the group GR3 set to the third setting value Vs3 (= 109V) stops, and the power supply from the power generation device 2 increases instead of the power supply device 5 of the group GR3, and the current i increases again.

[0074] As described above, the power supply control device 3 monitors the power supply and demand state in the power supply network 1 based on the current i, and selectively stops the power output from the power supply devices 5 and 6 to the power supply path 4 and the customer load 7 according to the power supply and demand state, thereby preventing reverse power flow from the power supply devices 5 and 6.

[0075] Next, the flow of the reverse power flow prevention control by the power supply control device 3 according to the first embodiment will be described.

[0076] FIG. 5 is a flowchart showing an example of the flow of the process of the reverse power flow prevention control by the power supply control device 3 according to the first embodiment.

[0077] First, in the power supply control device 3, the setting value setting unit 32 accesses the power supply devices 5 and 6 and sets different setting values for each power supply device 5 and 6 for each group (step S1). For example, as described above, the setting value setting unit 32 sets the first setting value Vs1 (= 107 V) for the power supply device 6 in group GR1, sets the second setting value Vs2 (= 108 V) for the power supply device 5 in group GR2, and sets the third setting value Vs3 (= 109 V) for the power supply device 5 in group GR3.

[0078] Next, the control unit 30 controls the power generation device 2 so that the voltage Vo of the power supply path 4 becomes the reference value Vb (= 106.5 V) (step S2). As a result, power can be output from the power supply devices 5 and 6 of all groups GR1 to GR3 to the power supply path 4 and the consumer load 7.

[0079] Next, the control unit 30 determines whether the current i flowing from the power generation device 2 to the power supply path 4 is equal to or less than the first threshold value ith1 (step S3). When the current i is greater than the first threshold value ith1 (step S3: NO), the control unit 30 continues to control the power generation device 2 so that the voltage Vo of the power supply path 4 becomes the reference value Vb.

[0080] On the other hand, when the current i is equal to or less than the first threshold value ith1 (step S3: YES), the control unit 30 performs operation control of the system connection protection relay 53 of the power supply devices 5 and 6 (step S4). Specifically, the control unit 30 controls the power generation device 2 so that the voltage Vo of the power supply path 4 becomes the reference value Vb + 1 V (= 106.5 V + 1 V = 107.5 V). As a result, the output of power from the power supply device 6 in group GR1, for which the first setting value Vs1 (= 107 V) is set, to the power supply path 4 and the consumer load 51 stops.

[0081] Next, the control unit 30 determines whether the current i flowing from the power generation device 2 to the power supply path 4 is equal to or less than the second threshold value ith2 (step S5). When the current i is greater than the second threshold value ith2 (step S5: NO), the control unit 30 continues to control the power generation device 2 so that the voltage Vo of the power supply path 4 becomes the reference value Vb + 1 V (= 107.5 V).

[0082] On the other hand, when the current i is equal to or less than the second threshold value ith2 (step S5: YES), the control unit 30 controls the operation of the system connection protection relay 53 of the power supply devices 5 and 6 (step S6). Specifically, the control unit 30 controls the power generation device 2 so that the voltage of the power supply path 4 becomes the reference value Vb + 2V (= 106.5V + 2V = 108.5V). As a result, in addition to the group GR1, the power supply from the power supply device 5 of the group GR2 where the second setting value Vs2 (= 108V) is set to the power supply path 4 and the customer load 51 is stopped.

[0083] Next, the control unit 30 determines whether the current i flowing from the power generation device 2 to the power supply path 4 is equal to or less than the third threshold value ith3 (step S7). When the current i is greater than the third threshold value ith3 (step S7: NO), the control unit 30 continues to control the power generation device 2 so that the voltage Vo of the power supply path 4 becomes the reference value Vb + 2V (= 108.5V).

[0084] On the other hand, when the current i is equal to or less than the third threshold value ith3 (step S7: YES), the control unit 30 controls the operation of the system connection protection relay 53 of the power supply devices 5 and 6 (step S8). Specifically, the control unit 30 controls the power generation device 2 so that the voltage Vo of the power supply path 4 becomes the reference value Vb + 3V (= 106.5V + 3V = 109.5V). As a result, in addition to the groups GR1 and GR2, the power supply from the power supply device 5 of the group GR3 where the third setting value Vs3 (= 109V) is set to the power supply path 4 and the customer load 51 is stopped.

[0085] When restoring the power supply devices 5 and 6 whose power output has been stopped, it is preferable to restore them in the same order as when they were stopped. For example, as in the above example, when the power output is stopped in the order of group GR1, group GR2, and group GR3, the power output by the power supply devices 5 and 6 is enabled in the order of group GR1, group GR2, and group GR3. According to this, since the stop periods of all the power supply devices can be equalized, the unfairness between the groups of the power supply devices 5 and 6 can be eliminated.

[0086] As described above, in the power supply network 1 according to Embodiment 1, among the plurality of inverter-based power supply devices 5 and 6, at least one of the power supply devices 5 and 6 has a setting value of a voltage or frequency that serves as a criterion for operating the system connection protection relay 53 different from the setting values of the other power supply devices 5 and 6, and the power supply control device 3 controls the power generation device 2 based on the measured value of the current i flowing through the power supply path 4 from the power generation device 2 so that the voltage of the power supply path 4 gradually exceeds the range defined by the setting value.

[0087] According to this, when the power demand on the consumer side decreases, instead of stopping all the power supply devices 5 and 6 at once, the power supply devices 5 and 6 can be selectively stopped. Thus, it is possible to prevent the occurrence of reverse power flow while suppressing a sharp increase in fuel consumption of the power generation device 2 and the disadvantages of the power selling business operator, etc.

[0088] Specifically, the plurality of inverter-based power supply devices 5 and 6 are divided into a plurality of groups GR1 to GR3. Among the plurality of groups GR1 to GR3, the power supply device 6 of group GR1 has a first setting value Vs1 (105 V) set, and the power supply devices 5 of groups GR2 and GR3 other than group GR1 have a second setting value Vs2 different from the first setting value Vs1 set as the voltage setting value. When the measured value of the current i is greater than the first threshold value ith1, the power supply control device 3 controls the power generation device 2 so that the voltage Vo of the power supply path 4 is within the range defined by the first setting value Vs1 (so that the voltage Vo of the power supply path 4 is less than the first setting value Vs1). When the measured value of the current i drops below the first threshold value ith1, the power supply control device 3 controls the power generation device 2 so that the voltage Vo of the power supply path 4 exceeds the range defined by the first setting value Vs1 and is within the range defined by the second setting value Vs2 (Vs1 ≤ Vo < Vs2).

[0089] According to this, when the measured value of the current i drops below the first threshold value ith1, only the power supply device 6 with the first setting value Vs1 set stops the power output when the system connection protection relay 53 operates, and the other power supply devices 5 continue the power output. In this way, it becomes easy to selectively stop the power output from a part of the plurality of inverter-based power supply devices 5 and 6. Also, thereby, since the power supplied by the power generation device 2 increases instead of the stopped power supply device 6, it becomes possible to avoid reverse power flow.

[0090] Also, the second setting value Vs2 is set for the power supply device 5 of group GR2 among the groups other than group GR1, and a third setting value Vs3 different from the first setting value Vs1 and the second setting value Vs2 is set for the power supply device 5 belonging to group GR3. When the current i drops below the second threshold value ith2, the control unit 30 controls the power generation device 2 so that the voltage Vo of the power supply path 4 exceeds the ranges defined by the first setting value Vs1 and the second setting value Vs2 and is within the range defined by the third setting value Vs3 (Vs2 ≤ Vo < Vs3).

[0091] According to this, when the current i drops below the second threshold value ith2, in addition to the power supply device 6 with the first setting value Vs1 set, the power supply device 5 with the second setting value Vs2 set stops the power output when the system connection protection relay 53 operates, and the power supply device 5 with the third setting value Vs3 set continues the power output. In this way, by increasing the number of groups of the power supply devices 5 and making the setting values different from each other, the power supply devices 5 and 6 to be stopped can be selected more finely, so that it is possible to more effectively prevent reverse power flow.

[0092] Also, by setting the smallest first setting value Vs1 (105 V) for the power supply device 6 with the largest power generation capacity, the reverse power flow prevention effect obtained when performing the operation control (step S4) of the first system connection protection relay 53 is large, so the frequency of repeatedly performing the operation control (steps S6, S8) of the system connection protection relay 53 is reduced, contributing to the realization of more stable power supply.

[0093] As described above, according to the power supply control device 3 according to the present embodiment, in the power supply network 1 in which the generator and a plurality of inverter-based power supply devices are connected to the distribution system, while making the most of the inverter-based power supply devices, it is possible to efficiently drive the generator.

[0094] ≪Embodiment 2≫ FIG. 6 is a diagram showing a specific configuration of the power supply control device 3 in the power supply network 1A according to Embodiment 2.

[0095] The power supply control device 3A according to Embodiment 2 is different from the power supply control device 3 according to Embodiment 1 in that the power supply device whose power output is stopped by the operation control of the system connection protection relay 53 is switched every fixed period, and is the same as the power supply control device 3 according to Embodiment 1 in other respects.

[0096] In the power supply control device 3A, the setting value setting unit 32A changes the setting values of the plurality of inverter-based power supply devices 5 and 6 so as to periodically switch the power supply devices 5 and 6 that stop power output when the system connection protection relay 53 operates.

[0097] FIG. 7 is a diagram showing an example of switching control of the setting value of the power supply device by the power supply control device 3A according to the second embodiment.

[0098] The power supply control device 3A switches the groups GR1 to GR3 of the power supply devices that stop power output when the system connection protection relay 53 operates every fixed time (hereinafter also referred to as "stop time") T1. For example, as shown in FIG. 7, first, the power supply control device 3A stops the power output from the group GR1, and after the elapse of the stop time T1, enables (restores) the power output from the group GR1 and stops the power output from the group GR2. After the elapse of the stop time T1 since the power output from the group GR2 was stopped, the power supply control device 3A restores the group GR2 and stops the power output from the group GR3. Then, after the elapse of the stop time T1 since the power output from the group GR3 was stopped, the power supply control device 3A restores the group GR3 and stops the power output from the group GR1 again.

[0099] The information on the stop time T1 that determines the switching cycle of the power supply devices to be the power output stop targets is stored in the storage unit 33A in advance, for example. For example, the control unit 30 measures the elapsed time since the power output from the power supply device to be the stop target was stopped by the operation control of the system connection protection relay 53. When the elapsed time reaches the stop time T1 stored in the storage unit 33A, the control unit 30 controls the setting value setting unit 32A to switch the setting value of the power supply device in the group where the power output is stopped and the setting value of the power supply device in the group where the power output is to be stopped next, thereby switching the power supply devices to be the power output stop targets.

[0100] The switching control process of the power supply device to be stopped will be specifically described below. FIG. 8 is a flowchart showing an example of the switching control process of the power supply device by the power supply control device 3A according to Embodiment 2.

[0101] Here, as an initial state, it is assumed that the first setting value Vs1 (107 V) is set for the power supply device 6 in one group GR1 among the plurality of inverter-based power supply devices 5 and 6, and the second setting value Vs2 (108 V) is set for the other groups GR2 and GR3. Also, here, the case of switching the power supply device to be stopped in the order illustrated in FIG. 7 will be taken as an example for explanation.

[0102] For example, when the current i in the power supply path 4 decreases and becomes equal to or less than the threshold value ith1 in a state where the power supply devices 5 and 6 in all groups GR1 to GR3 are operable. At this time, the control unit 30A of the power supply control device 3A controls the operation of the system connection protection relay 53 (step S20). Specifically, the control unit 30A controls the power generation device 2 so that the voltage Vo of the power supply path becomes a voltage (for example, 107.5 V) higher than the first setting value Vs1 (107 V). As a result, the power output from the power supply device 6 in the group GR1 where the first setting value Vs1 (107 V) is set to the power supply path 4 and the consumer load 7 stops (step S21). At this time, the control unit 30A starts measuring time.

[0103] Next, the control unit 30A determines whether the elapsed time t since the power output of the power supply device 6 in the group GR1 stopped has reached the stop time T1 (step S22). If the elapsed time t has not reached the stop time T1 (step S22: NO), the control unit 30A continues the state in which the power output by the power supply device 6 in the group GR1 is stopped.

[0104] On the other hand, when the elapsed time t reaches the stop time T1 (step S22: YES), the control unit 30A changes the group of the power supply device for which the power output stop target is set (step S23).

[0105] Specifically, the control unit 30A changes the setting value of the power supply device of the group whose power output was stopped in step S21 and the setting value of the power supply device of the group whose power output will be stopped next. For example, the control unit 30A controls the setting value setting unit 32A to change the setting value of the power supply device 6 of the group GR1 whose power output was stopped in step S21 from the first setting value Vs1 (107V) to the second setting value Vs2 (108V), and at the same time, changes the setting value of the power supply device 5 of the group GR2 which will be the next target for stopping power output from the second setting value Vs2 (108V) to the first setting value Vs1 (107V).

[0106] As a result, while the power supply device 6 of the group GR1 returns and power output becomes possible (step S24), the power supply device 5 of the group GR2 stops power output (step S25).

[0107] Next, the control unit 30A determines whether the elapsed time t since the power output by the power supply device 5 of the group GR2 stopped has reached the stop time T1 (step S26). If the elapsed time t has not reached the stop time T1 (step S26: NO), the control unit 30A continues the state in which the power output by the power supply device 5 of the group GR2 is stopped.

[0108] On the other hand, when the elapsed time t reaches the stop time T1 (step S26: YES), the control unit 30A changes the group of power supply devices that are the targets for stopping power output (step S27). For example, the control unit 30A controls the setting value setting unit 32A to change the setting value of the power supply device 5 of the group GR2 whose power output was stopped in step S25 from the first setting value Vs1 (107V) to the second setting value Vs2 (108V), and at the same time, changes the setting value of the power supply device 5 of the group GR3 to be stopped next from the second setting value Vs2 (108V) to the first setting value Vs1 (107V).

[0109] As a result, while the power supply device 6 of the group GR2 returns and power output becomes possible (step S28), the power supply device 5 of the group GR3 stops power output (step S29).

[0110] Next, the control unit 30A determines whether or not the elapsed time t since the power output by the power supply device 5 in the group GR3 has stopped has reached the stop time T1 (step S30). When the elapsed time t has not reached the stop time T1 (step S30: NO), the control unit 30A continues the state in which the power output by the power supply device 5 in the group GR3 is stopped.

[0111] On the other hand, when the elapsed time t has reached the stop time T1 (step S30: YES), the control unit 30A changes the group of the power supply device whose power output is to be stopped (step S31). For example, the control unit 30A controls the setting value setting unit 32A to change the setting value of the power supply device 5 in the group GR3 stopped in step S29 from the first setting value Vs1 (107 V) to the second setting value Vs2 (108 V), and at the same time, changes the setting value of the power supply device 5 in the group GR1 to be stopped next from the second setting value Vs2 (108 V) to the first setting value Vs1 (107 V).

[0112] As a result, while the power supply device 6 in the group GR3 returns and power output becomes possible (step S32), again, the power supply device 5 in the group GR1 stops power output (step S21). After that, the same process is repeatedly executed, and the groups GR1 to GR3 that stop power output are switched every fixed time T1.

[0113] As described above, the power supply control device 3A according to the second embodiment switches the power supply devices 5 and 6 that stop power output every fixed time when the system connection protection relay 53 operates. According to this, it is possible to avoid that only some of the power supply devices 5 continue to stop for reverse power flow prevention, so it is possible to eliminate the unfairness between the groups of power supply devices.

[0114] ≪Expansion of the Embodiment≫ Although the invention made by the present inventors has been specifically described based on the embodiments above, it goes without saying that the present invention is not limited thereto and can be variously modified without departing from the gist thereof.

[0115] For example, in Embodiment 1, the case where the smallest first setting value Vs1 (e.g., 105 V) is set for the power supply device 6 with the largest power generation amount is shown, but the present invention is not limited thereto, and the setting value of the power supply device may be set such that the smaller the power generation amount, the smaller the value. For example, the control unit 30 of the power supply control device 3 monitors the power generation amounts of the power supply devices 5 and 6 via the communication network 8, and the setting value setting unit 32 may set the setting values of the power supply devices 5 and 6 according to the power generation amounts of the power supply devices 5 and 6. According to this, a sudden change in the power supply state due to the stop of the power supply device can be suppressed, and the equalization of the power generation amounts of the power supply devices in the entire power supply network 1 can be achieved.

[0116] In the above embodiment, the case where the setting value of the overvoltage relay (OVR) is set to a different value for each group and the voltage Vo of the power supply path 4 is gradually increased to selectively stop the power output from the power supply devices 5 and 6 is illustrated, but the present invention is not limited thereto.

[0117] For example, the setting value of the undervoltage relay (UVR) may be set to a different value for each group, and the voltage Vo of the power supply path 4 may be gradually decreased to selectively stop the power output from the power supply devices 5 and 6. More specifically, the first setting value Vs1 is set for the UVR of the power supply device in group GR1, the second setting value Vs2 (<Vs1) is set for the UVR of the power supply device in group GR2, and the third setting value Vs3 (<Vs2 <Vs1) is set for the UVR of the power supply device in group GR3. Then, the voltage Vo of the power supply path 4 is controlled to gradually decrease from the reference value Vb toward the third setting value Vs3. According to this, the power supply devices in groups GR1 to GR3 can be stopped step by step.

[0118] Alternatively, the setting values of the over-frequency relay (OFR) may be set to different values for each group, and the output of power from the power supply devices 5 and 6 may be selectively stopped by gradually increasing the frequency of the power supply path 4. More specifically, a first setting value Fs1 of the frequency is set for the OFR of the power supply device in group GR1, a second setting value Fs2 (>Fs1) of the frequency is set for the OFR of the power supply device in group GR2, and a third setting value Fs3 (>Vs2>Vs1) is set for the OFR of the power supply device in group GR3. Then, control is performed such that the frequency of the power supply path 4 gradually increases from the reference value Fb toward the third setting value Fs3. According to this, it becomes possible to gradually stop the power supply devices in groups GR1 to GR3.

[0119] Alternatively, the setting values of the under-frequency relay (UFR) may be set to different values for each group, and the output of power from the power supply devices 5 and 6 may be selectively stopped by gradually decreasing the frequency of the power supply path 4. More specifically, a first setting value Fs1 of the frequency is set for the UFR of the power supply device in group GR1, a second setting value Fs2 (<Fs1) of the frequency is set for the UFR of the power supply device in group GR2, and a third setting value Fs3 (<Vs2<Vs1) is set for the UFR of the power supply device in group GR3. Then, control is performed such that the frequency of the power supply path 4 gradually decreases from the reference value Fb toward the third setting value Fs3. According to this, it becomes possible to gradually stop the power supply devices in groups GR1 to GR3.

[0120] Also, the above flowchart shows an example for explaining the operation and is not limited thereto. 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, or some processes may be performed in parallel.

Explanation of Signs

[0121] 1, 1A… Power supply network, 2… Power generation device, 3, 3A… Power supply control device, 4… Power supply path, 5_1~5_n, 6… Inverter-based power supply device, 7… Customer load, 8… Communication network, 20… Power generation control device, 21… Prime mover, 22… Generator, 23… Circuit breaker, 30, 30A… Control unit, 31… Current value acquisition unit, 32, 32A… Setting value setting unit, 33, 33A… Memory unit, 52… PCS, 53… System connection protection relay, GR1~GR3… Groups, Sd… Indication signal.

Claims

1. A power supply network comprising a power supply path for supplying power to a home load, a power generation device that generates power based on mechanical energy and supplies the power to the power supply path, and a plurality of inverter-based power supply devices having a system connection protection relay and connected to the power supply path, wherein the power supply control device controls the supply of power to the power supply path, at least one of the plurality of inverter-based power supply devices has a setting value of voltage or frequency that serves as a criterion for operating the system connection protection relay set to a value different from the setting value of the other power supply devices, the system connection protection relay enables the output of power from the power supply device when the voltage or frequency of the power supply path is within the range defined by the setting value, and stops the output of power from the power supply device when the voltage or frequency of the power supply path exceeds the range defined by the setting value, the power supply control device has a current value acquisition unit that acquires a measured value of the current flowing on the power receiving side of the power supply path from the power generation device, and a control unit that controls the power generation device so that the voltage or frequency of the power supply path gradually exceeds the range defined by the setting value in response to a change in the measured value of the current, the plurality of inverter-based power supply devices are divided into a plurality of groups, for the power supply devices of the first group among the plurality of groups, a first value is set as the setting value of voltage or frequency, and for the power supply devices of the groups other than the first group, a second value different from the first value is set as the setting value of voltage or frequency, when the measured value of the current is greater than a first threshold, the control unit controls the power generation device so that the voltage or frequency of the power supply path is within the range defined by the first value, and when the measured value of the current drops below the first threshold, the control unit controls the power generation device so that the voltage or frequency of the power supply path exceeds the range defined by the first value and is within the range defined by the second value Power supply control device.

2. The power supply control device according to claim 1, ​ Among the groups other than the first group, the power supply device of the second group has the second value set as the set value of the voltage or frequency, and the power supply devices belonging to the groups other than the first group and the second group have a third value different from the first value and the second value set as the set value of the voltage or frequency. When the current drops below the second threshold, the control unit controls the power generation device so that the voltage or frequency of the power supply path exceeds the ranges defined by the first value and the second value and is within the range defined by the third value. Power supply control device.

3. In the power supply control device according to claim 1 or 2, The set value of the power supply device with the largest power generation amount among the plurality of inverter-based power supply devices is set to the first value. Power supply control device.

4. In the power supply control device according to any one of claims 1 to 3, It further has a set value setting unit for setting the set values of the plurality of inverter-based power supply devices, The set value setting unit changes the set values of the plurality of inverter-based power supply devices so that the power supply devices that stop power output when the system connection protection relay operates are switched every certain time. Power supply control device.

5. In the power supply control device according to any one of claims 1 to 3, It further has a set value setting unit for setting the set values of the plurality of inverter-based power supply devices, The set value setting unit sets the set values of the plurality of inverter-based power supply devices so that the smaller the power generation amount of the power supply device, the smaller the value. Power supply control device.

6. A power supply control device according to any one of claims 1 to 5, The power supply path The plurality of inverter-based power supply devices connected to the power supply path, And a power supply network comprising the consumer load connected to the power supply path. Power supply network.

7. In a power supply network comprising a power supply path for supplying power to a consumer load, a power generation device that generates power based on mechanical energy and supplies the power to the power supply path, and a plurality of inverter-based power supply devices having a system connection protection relay and connected to the power supply path, a power supply control method for controlling the supply of power to the power supply path, At least one of the plurality of inverter-based power supply devices has a setting value of voltage or frequency that serves as a criterion for operating or not operating the system connection protection relay set to a value different from the setting value of the other power supply devices. The system connection protection relay enables the output of power from the power supply device when the voltage or frequency of the power supply path is within the range defined by the setting value, and stops the output of power from the power supply device when the voltage or frequency of the power supply path exceeds the range defined by the setting value. It includes a first step of obtaining a measured value of the current flowing on the power receiving side from the power generation device in the power supply path, and a second step of controlling the power generation device so that the voltage or frequency of the power supply path gradually exceeds the range defined by the setting value in response to a change in the measured value of the current. The plurality of inverter-based power supply devices are divided into a plurality of groups. For the power supply devices in the first group among the plurality of groups, a first value is set as the setting value of voltage or frequency, and for the power supply devices in the groups other than the first group, a second value different from the first value is set as the setting value of voltage or frequency. The second step includes a step of controlling the power generation device so that the voltage or frequency of the power supply path is within the range defined by the first value when the measured value of the current is greater than a first threshold, and a step of controlling the power generation device so that the voltage or frequency of the power supply path exceeds the range defined by the first value and is within the range defined by the second value when the measured value of the current drops below the first threshold. Power supply control method.

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