DC microgrid and control method for DC microgrid

Abstract

According to the present invention, consumer facilities that comprise a converter (34) that supplies power from a generator (35) to an in-home power distribution line (23), a switch (32) that connects or disconnects the in-home power distribution line (23) and a load (33), and an apparatus control device (31) that controls the converter (34) and the switch (32) are connected by a power distribution line (2). Each apparatus control device (31) ascertains the operating state of the respective generator (35) by communication, and, upon disconnection from a power system, each apparatus control device (31) connects the switch (32) at the respective consumer 3 on the basis of the operating state of the generator (35) to supply power to the load (33).

Description

DC microgrid and control method for DC microgrid

[0001] The present disclosure relates to a DC microgrid and a method for controlling a DC microgrid.

[0002] In recent years, there has been a demand for the construction of highly resilient microgrids that utilize energy-generating power sources such as solar and wind power generators, and energy-storing power sources such as stationary storage batteries and storage batteries for EVs (electric vehicles).

[0003] To build an alternating current (AC) microgrid, there is an AC microgrid that is configured by interconnecting a power conditioning system (PCS) (for each PV) and a storage battery PCS based on a commercial power source. There is also an AC microgrid that is equipped with a synchronous generator that can follow instantaneous load fluctuations when isolated from the commercial power source, or an asynchronous generator that can supply power to all loads within the microgrid (for example, a storage battery PCS that operates as a voltage source in an independent operation, or a PV PCS that operates as a current source).

[0004] In a small-scale power system capable of autonomous operation using a power storage system when a power outage occurs in the power system, an AC microgrid is disclosed that includes a voltage measurement unit that measures the voltage at the power receiving point of a consumer, a memory unit that stores load control information during autonomous operation, a determination unit that determines the start of autonomous operation after a power outage occurs in the power system using the load control information and the voltage value measured by the voltage measurement unit, and a load control unit that performs load restriction when determining the start of autonomous operation (see, for example, Patent Document 1).

[0005] Patent No. 7076669

[0006] Generally, AC microgrid generators are large and expensive, and each connected converter must be synchronized. In DC (direct current) microgrids, controlling voltage allows for the connection of different power sources and power flow control. Furthermore, multiple small power sources can be operated as voltage source power sources, virtually treating them as large-capacity voltage source power sources. By connecting a large number of small-capacity PV panels and storage battery power sources, such as those installed in homes, a DC microgrid can be constructed with a relatively simple configuration. However, no black start method has been established for a DC microgrid that experiences a power outage due to an accident or other reason, or when the DC microgrid is interconnected with the power grid and the power grid power outage causes the DC microgrid's supply power to be insufficient compared to the load power in the DC microgrid, resulting in a DC bus voltage drop and a power outage.

[0007] The present disclosure discloses technology for solving the above-mentioned problems, and aims to provide a DC microgrid that enables black start and stable power source sharing with a simple configuration, and a control method for the DC microgrid.

[0008] The DC microgrid disclosed herein is a DC microgrid connected to a power system in which consumers, each of which is composed of a generator converter that supplies power from a generator to a distribution line within the consumer's premises, a load switch that connects or disconnects a load to the distribution line within the consumer's premises, and an equipment control device that controls the generator converter and the load switch, are connected via two or more distribution lines, and each of the equipment control devices grasps the operating status of each of the generators via a communication network.When the generator is disconnected from the power system and the load is separated, each of the equipment control devices grasps the operating status of each of the generators and connects the load switch of each of the consumers based on the operating status to supply power to the load. The DC microgrid of the present disclosure includes one or more first consumers connected to a distribution line, each first consumer comprising a generator converter that supplies power from a generator to a distribution line within a first consumer, a storage battery converter that supplies power from a storage battery to the distribution line within the first consumer or stores power from the distribution line within the first consumer in the storage battery, a first load switch that connects or disconnects the distribution line within the first consumer to a first load, and a first equipment control device that controls the generator converter, the storage battery converter, and the first load switch, and one or more second consumers connected to a distribution line, each second consumer comprising a second load switch that connects or disconnects a distribution line within a second consumer to a second load and a second equipment control device that controls the second load switch. In a DC microgrid connected to a power system, the first and second equipment control devices are connected via the power distribution line, and the first and second equipment control devices grasp the operating state of the generator and the operating state of the storage battery via a communication network. When the first and second loads are disconnected from the power system and the first and second equipment control devices grasp the operating state of the generator and the operating state of the storage battery, and connect the first load switch of the first consumer and the second load switch of the second consumer based on the operating state and the operating state to supply power to the first and second loads.The control method of the DC microgrid disclosed herein is a DC microgrid connected to a power system in which consumers, each of which is composed of a generator converter that supplies power from a generator to a distribution line within a consumer's premises, a load switch that connects or disconnects a load to the distribution line within the consumer's premises, and an equipment control device that controls the generator converter and the load switch, are connected via two or more distribution lines, and each of the equipment control devices grasps the operating state of each of the generators via a communication network. The control method of the DC microgrid disclosed herein is a DC microgrid connected to a power system in which, when a consumer is disconnected from the power system and the load is separated, one of the equipment control devices is started up to output a start command to the generator converter, start up the generator, and supply power to the distribution line within the consumer's premises to establish a voltage of the distribution line; and each of the equipment control devices: The method includes a generator converter startup step in which a startup command is output to each of the generator converters to start each of the generators; a generator operating status acquisition step in which each of the equipment control devices acquires the operating status of the generators of other consumers via a communication network; and an output power and load power comparison step in which each of the equipment control devices compares the total value (P) of the output power that can be output of each of the generators with the total value (L) of the load power of each of the loads, and if P≧L, proceeds to a switch connection step, and if P<L, proceeds to a standby step, wherein in the switch connection step, each of the equipment control devices outputs a connection command to each of the load switches to supply power to each of the loads, and in the standby step, waits for a predetermined time and then returns to the generator operating status acquisition step.The control method of a DC microgrid disclosed herein is a DC microgrid connected to a power system in which consumers, each of which is composed of a generator converter that supplies power from a generator to a distribution line within a consumer's premises, a load switch that connects or disconnects a load to the distribution line within the consumer's premises, and an equipment control device that controls the generator converter and the load switch, are connected via two or more distribution lines, and each of the equipment control devices grasps the operating state of each of the generators via a communication network. The control method includes the steps of: when a consumer is disconnected from the power system and the load is separated, starting one of the equipment control devices to output a start-up command to the generator converter, starting the generator, and supplying power to the distribution line within the consumer's premises to establish a voltage of the distribution line; the load power supply status confirmation step of checking whether power has been supplied to all the loads, and terminating the processing if power has been supplied to all the loads, and proceeding to a standby step if power has not been supplied to any of the loads, and the standby step of waiting for a predetermined time and then returning to the generator operating status acquisition step.

[0009] According to the DC microgrid of the present disclosure, it is possible to realize a DC microgrid that enables a black start and allows stable power source sharing with a simple configuration. According to the DC microgrid control method of the present disclosure, it is possible to realize a DC microgrid that enables a black start and allows stable power source sharing with a simple configuration.

[0010] 7A is a diagram illustrating an example of load priorities in a DC microgrid according to embodiment 1. FIG. 7B is a diagram illustrating an example of prioritized load capacities in a DC microgrid according to embodiment 1. FIG. 7B is a diagram illustrating an example of prioritized load capacities in a DC microgrid according to embodiment 1. FIG. 7C is a diagram illustrating an example of a hardware configuration of an equipment control device for a DC microgrid according to embodiments 1 and 2. FIG. 7D is a diagram illustrating an example of a configuration of a DC microgrid according to embodiment 2. FIG. 7E is a diagram illustrating an example of a configuration of a DC microgrid according to embodiment 2. FIG. 7F is a diagram illustrating an example of a configuration of a DC microgrid according to embodiment 2. FIG. 7G is a diagram illustrating an example of a configuration of a DC microgrid according to embodiment 2. FIG. 7H is a diagram illustrating an example of a configuration of a DC microgrid according to embodiment 2. FIG. 7I is a diagram illustrating an example of a configuration of a DC microgrid according to embodiment 2. FIG. 7J is a diagram illustrating an example of a configuration of a DC microgrid according to embodiment 2. FIG. 7J is a diagram illustrating an example of a configuration of a DC microgrid according to embodiment 2.

[0011] Embodiment 1. Embodiment 1 relates to a DC microgrid in which consumer equipment, each of which includes a generator converter that supplies power from a generator to a consumer's distribution line, a load switch that connects or disconnects a load to the consumer's distribution line, and an equipment control device that controls the generator converter and the load switch, is connected via a distribution line, and each equipment control device grasps the operating state of the generator via communication, and when the generator is disconnected from the power grid, each equipment control device connects the load switch of each consumer based on the operating state of each generator to supply power to the load. Moreover, embodiment 1 relates to a control method of this DC microgrid.

[0012] The DC microgrid and a control method for the DC microgrid according to the first embodiment will be described below with reference to Fig. 1, which is a schematic configuration diagram of the DC microgrid, Fig. 2, which is a schematic configuration diagram of the equipment control device, Fig. 3, which is an operation flow diagram when a power outage occurs, Fig. 4, which is an operation flow diagram for black start, Figs. 5 and 6, which are flowcharts of the control method for the DC microgrid, Fig. 7A, which is an explanatory diagram of an example of load priorities, Fig. 7B, which is an explanatory diagram of an example of prioritized load capacities, and Fig. 8, which is an example of the hardware configuration of the equipment control device. Note that in each diagram, the same or corresponding parts are designated by the same reference numerals.

[0013] The overall configuration and operation of a DC microgrid 1 will be described with reference to Fig. 1. Note that the DC microgrid 1 is connected to a power grid 200 during normal operation, and if an accident or the like occurs on the power grid 200 side, it is disconnected and operates in islanded mode. The DC microgrid 1 is composed of a distribution line 2 and consumers 3, 4, and 5. Consumers 3, 4, and 5 are connected via the distribution line 2. Note that the configuration in Fig. 1 is an example, and the number of consumers may be one or four or more.

[0014] In the first embodiment, since the consumers 3, 4, and 5 are assumed to have basically the same equipment configuration, the consumer 3 will be described as a representative example where appropriate. The consumer 3 includes an equipment control device 31, a load switch 32, a load 33, a generator converter 34, and a generator 35. The equipment control device 31, the load switch 32, and the generator converter 34 are connected to a consumer-interior distribution line 23. The consumer-interior distribution line 23 is connected to a distribution line 2. The distribution line 2 and the consumer-interior distribution lines 23, 24, and 25 are DC buses, and necessary converters (AC / DC, DC / DC, DC / AC) are installed between the load switch 32 and the load 33 or within the load, but are not shown. For simplicity of explanation, the consumer-interior distribution line 23 will be referred to as the consumer-interior distribution line 23, the load switch 32 as the switch 32, and the generator converter 34 as the converter 34, where appropriate.

[0015] The switch 32 controls the power supply to the load 33 by connecting or disconnecting it. The converter 34 supplies power from the generator 35 to the home distribution line 23. The generator 35 is generally considered to be a solar generator, but the type of generator 35 is not limited to this, and may be a wind power generator, a gas turbine generator, a fuel cell, or the like. Furthermore, if a storage battery is used as the generator 35, power can be supplied to the home distribution line 23, so this is also applicable and the type of storage battery is not limited. The equipment control device 31 monitors and controls the status of each device (i.e., the switch 32, the load 33, the converter 34, and the generator 35) in the consumer 3.

[0016] The consumer 4 includes an equipment control device 41, a load switch 42, a load 43, a generator converter 44, and a generator 45. The equipment control device 41, the load switch 42, and the generator converter 44 are connected by a home distribution line 24. The home distribution line 24 is connected to the distribution line 2. The functions of the equipment control device 41, the load switch 42, the load 43, the generator converter 44, and the generator 45 are the same as those of the respective devices of the consumer 3.

[0017] The consumer 5 includes an equipment control device 51, a load switch 52, a load 53, a generator converter 54, and a generator 55. The equipment control device 51, the load switch 52, and the generator converter 54 are connected by a home distribution line 25. The home distribution line 25 is connected to the distribution line 2. The functions of the equipment control device 51, the load switch 52, the load 53, the generator converter 54, and the generator 55 are the same as those of the respective devices of the consumer 3.

[0018] The home distribution line 23 is connected to the consumer 4 and the consumer 5 via the distribution line 2. The appliance control device 31 of the consumer 3 is also connected to the appliance control device 41 of the consumer 4 and the appliance control device 51 of the consumer 5 via the communication network 21. The appliance control devices 31, 41, and 51 transmit operation information via the communication network 21 to grasp the operating status of the appliances in each consumer. This communication method can use a smart meter communication network or a communication network using a mobile phone network. Other communication networks can also be used.

[0019] Next, the configurations and functions of the equipment control devices 31, 41, and 51 will be described with reference to Fig. 2, using the equipment control device 31 as a representative. The equipment control device 31 includes a monitoring unit 61, a determining unit 62, a command unit 63, and a communication unit 64. The monitoring unit 61 of the equipment control device 31 acquires an operating status signal output from the converter 34 and grasps the operating status of the converter 34. The operating status of the converter 34 includes the operating status of the generator 35. The operating status of the converter 34 is transmitted to and shared with the equipment control device 41 of the consumer 4 and the equipment control device 51 of the consumer 5 via the communication unit 64 and the communication network 21. In addition, the operating status of converter 44 obtained by the monitoring unit 61 of the equipment control device 41 of consumer 4 and the operating status of converter 54 obtained by the monitoring unit 61 of the equipment control device 51 of consumer 5 are also shared by the equipment control devices 31, 41, and 51, and the equipment control devices 31, 41, and 51 grasp the operating status of all converters (converter 34, converter 44, and converter 54) of the DC microgrid 1.

[0020] The determination unit 62 of the equipment control device 31 determines whether to execute the processing of the power outage flow ( FIG. 3 ) and black start flow ( FIG. 4 ), which will be described in detail later. In the power outage flow, when a power outage is detected at the power receiving point of the consumer 3 with the power grid 200, the switch 32 of the consumer 3 is opened to disconnect the load 33. In the black start flow, the amount of output power that can be determined from the operating state of each converter (converters 34, 4, 54) in the DC microgrid 1 is compared with the total amount of power of all loads (loads 33, 43, 53) in the DC microgrid 1, and a determination is made as to whether to connect the switch 32 in the consumer 3, i.e., whether to supply power to the load 33. The determination unit 62 of the equipment control device 41 and the determination unit 62 of the equipment control device 51 also make similar determinations.

[0021] Based on instructions from the determination unit 62, the command unit 63 of the equipment control device 31 outputs a start command to the converter 34 in the consumer 3 required to execute the power outage flow and the black start flow, and a connection or opening command to the switch 32. Note that the command unit 63 of the equipment control device 41 and the command unit 63 of the equipment control device 51 similarly output start commands to the converter 44 and the converter 54, and a connection or opening command to the switch 42 and the switch 52, respectively.

[0022] Here, we will explain the constant voltage (CV) control by the converter 34 required for normal operation of the DC microgrid 1. If the power supplied from each generator (generators 35, 45, 55) to the distribution line 2 and the power consumed by each load (loads 33, 43, 53) are not simultaneously equal in amount, the voltage of the distribution line 2 may fluctuate, resulting in overvoltage or undervoltage, which may lead to the shutdown or failure of, for example, the converters (converters 34, 44, 54). For this reason, in DC power distribution, CV control is performed in which one of the converters, for example, the converter 34 of the consumer 3, controls the output power to the distribution line 2 to maintain a constant voltage. The voltage that is to be controlled to a constant value is called a target voltage. Furthermore, if the generator 35 connected to the converter 34 is a storage battery, it can not only supply power to the distribution line 2, but also store surplus power in the storage battery when it occurs in the distribution line, thereby maintaining a constant voltage of the distribution line 2.

[0023] The behavior when an accident or the like occurs on the power grid 200 side, the DC microgrid 1 is disconnected from the power grid 200, and the distribution line 2 becomes voltageless will be described. To supply power to the loads 33, 43, and 53 of the DC microgrid 1, the necessary power must be supplied to the distribution line 2 and the home distribution lines 23, 24, and 25. For example, consider a case where one of the switches 32, 42, and 52 is in a connected state in the initial operation state of the generator 35. Even when the converter 34 starts up and supplies power from the generator 35 to the home distribution line 23, if the output power of the converter 34 is smaller than the power consumption of the connected load, the voltage of the distribution line 2 and the home distribution lines 23, 24, and 25 cannot be maintained, and the voltage drops, causing the converter 34 to shut down.

[0024] To prevent this, when starting up the DC microgrid 1, each switch (switches 32, 42, 52) in each consumer (consumer 3, 4, 5) needs to be in an open state. Therefore, if a power outage occurs in the DC microgrid 1, a monitoring unit 61 of the equipment control device 31 detects the power outage using a power outage detection unit (not shown) or an undervoltage relay (not shown) in the equipment control device 31, and a command unit 63 of the equipment control device 31 outputs an open command to the switch 32 to disconnect the load 33. Note that, although the equipment control device 31 stops operating when the voltage of the distribution line 2 disappears, providing a capacitor bank in the equipment control device 31 makes it possible to maintain the control power supply of the equipment control device 31 for a short time from the occurrence of the power outage until the switch 32 opens. The equipment control devices 41 and 51 also perform the same operation to open the switches 42 and 52 and disconnect the loads 43 and 53.

[0025] As a result, in the event of a power outage, all loads (loads 33, 43, and 53) are disconnected from the distribution line 2 and the home distribution lines 23, 24, and 25. Because all loads are disconnected from the distribution line 2, even if any of the converters (converters 34, 44, and 54) starts up again and voltage is applied to the distribution line 2, the voltage of the distribution line 2 cannot be maintained, and converter 34 will not stop due to a voltage drop. In this state, the black start flow can be started.

[0026] The processing flow in the event of a power outage in Fig. 3 will be described using the consumer 3 as an example. This flow in the event of a power outage includes step 01 (S01) and step 02 (S02), and is activated periodically. In step 01 (S01), the monitoring unit 61 of the appliance control device 31 acquires voltage information on the home distribution line 23, and the determination unit 62 determines whether a power outage has occurred. If a power outage has occurred, in step 02 (S02), the switch 32 is opened to disconnect the load 33.

[0027] The following description will be given assuming that the distribution line voltage establishment operation is performed by the consumer 3. When the DC microgrid 1 is in a power outage state, the distribution line 2 and the home distribution lines 23, 24, and 25 are voltageless. From this state, the converter 34 is started up and CV control is performed on the home distribution line 23, thereby establishing voltage. In order for power to be supplied from the home distribution lines 23, 24, and 25 in the DC microgrid 1 to the respective device control devices 31, 41, and 51 and for them to operate, the generator 35 needs to be able to output power greater than the total power consumption of the device control devices 31, 41, and 51.

[0028] A case will be described in which an operator manually establishes the voltage of the distribution line 2 regardless of the time of day (daytime, nighttime, etc.) or the type of generator 35. The operator manually starts the generator 35, such as a storage battery, a gas turbine generator, or a fuel cell, and the converter 34 to supply power to the home distribution line 23. It is assumed that the power initially supplied to the equipment control device 31 is secured separately and connected by the operator. When the converter 34 and the generator 35 are started, power is supplied to the home distribution line 23, and the voltage of the distribution line 2 and the home distribution lines 23, 24, and 25 is established. As a result, the equipment control device 41 of the customer 4 is supplied with power from the home distribution line 24, and the equipment control device 51 of the customer 5 is supplied with power from the home distribution line 25. Each of the equipment control devices 31, 41, and 51 recognizes via the communication network 21 that the converters 34, 44, and 54 of the customers 3, 4, and 5 have completed startup.

[0029] If the generator 35 is a solar power generator (PV generator), when the amount of sunlight recovers, the generator 35 and the converter 34 start up and can automatically supply power to the home distribution line 23 .

[0030] Once the startup of the equipment control devices 31, 41, and 51 of the consumers 3, 4, and 5 is complete, each of the equipment control devices 31, 41, and 51 starts the black start flow ( FIG. 4 ). Each of the equipment control devices 31, 41, and 51 outputs a startup command to each of the converters 34, 44, and 54. As with the converter 34 that is already under CV control, the equipment control devices 41 and 51 perform CV control on the in-home power distribution lines 24 and 25. Note that, since the converter 34 of the consumer 3 is assumed to be supplying only the power necessary to start up each of the equipment control devices 31, 41, and 51, by executing the black start flow, it commands the converter 34 and the generator 35 to start up at rated output.

[0031] The black start flow of FIG. 4 will be described using consumer 3 as an example. This black start flow includes steps 11 (S11) to 18 (S18). In step 11 (S11), the equipment control device 31 outputs a startup command to the converter 34. In step 12 (S12), the equipment control device 31 checks whether startup of the converter 34, i.e., startup of the generator 35, has been completed. If startup of the converter 34 has been completed, the process proceeds to step 13 (S13); if startup has not been completed, the process proceeds to step 14 (S14). In step 13 (S13), the equipment control device 31 acquires the operating status of the converter 34, i.e., the operating status of the generator 35. In step 14 (S14), the process waits for a predetermined time and then returns to step 12 (S12). In step 15 (S15), the equipment control device 31 acquires the operating status of the converters 44 and 54 of other consumers 4 and 5, specifically, the operating status of the generators 45 and 55, via the communication network 21. In step 16 (S16), the equipment control device 31 compares the total value (P) of the available output power of each generator 35, 45, 55 in the DC microgrid with the total value (L) of the load power of each load 33, 43, 53. If P≧L, the process proceeds to step 17 (S17), and if P<L, the process proceeds to step 18 (S18). In step 17 (S17), the equipment control device 31 closes the switch 32 to supply power to the load 33. In step 18 (S18), the process waits for a predetermined time and then returns to step 15 (S15).

[0032] The above-described DC microgrid control method will be summarized based on flowchart FIG. 5. Processing common to the consumers 3, 4, and 5 will be described using the consumer 3 as a representative. The DC microgrid control method of the first embodiment includes the following steps 21 (S21) to 26 (S26) using a DC microgrid 1 in which the facilities of the consumers 3, 4, and 5 are connected via a distribution line 2 and each facility includes converters 34, 44, and 54 that supply power from generators 35, 45, and 55 to home distribution lines 23, 24, and 25, switches 32, 42, and 52 that connect or disconnect the home distribution lines 23, 24, and 25 to loads 33, 43, and 53, and device control devices 31, 41, and 51 that control the converters 34, 44, and 54 and the switches 32, 42, and 52. The device control devices 31, 41, and 51 grasp the operating states of the generators 35, 45, and 55 via a communication network 21.

[0033] In step 21 (S21), which is the distribution line voltage establishment step, the operator starts the equipment control device 31 of the consumer 3, outputs a start-up command to the converter 34, starts the generator 35, and supplies power to the home distribution line 23 to establish the voltage of the distribution line 2. Here, the generator 35 does not need to output rated power; it only needs to output the power required to start each of the equipment control devices 31, 41, and 51. Here, the equipment control device 31 confirms that sufficient power is being supplied to the home distribution line 23, i.e., the distribution line 2, to each of the equipment control devices 31, 41, and 51 of the consumers 3, 4, and 5. In this state, the black start flow described above can be started.

[0034] In step 22 (S22), a generator converter startup step, each of the device control devices 31, 41, 51 outputs a startup command to each of the converters 34, 44, 54 to start up each of the generators 35, 45, 55. Note that since the generator 35 of the consumer 3 has already started up at low output, a command is issued to start it up at rated output.

[0035] In step 23 (S23), which is the generator operating state acquisition step, each of the equipment control devices 31, 41, 51 acquires the operating states of the converters 34, 44, 54 of other consumers, i.e., the operating states of the generators 35, 45, 55, via the communication network 21.

[0036] In step 24 (S24), a step of comparing the available output power and the load power, each device control device 31, 41, 51 compares the total value (P) of the available output power of each generator 35, 45, 55 with the total value (L) of the load power of each load 33, 43, 53. If P≧L, proceed to step 25 (S25), and if P<L, proceed to step 26 (S26).

[0037] In step 25 (S25), which is a switch connection step, the device control devices 31, 41, and 51 output connection commands to the switches 32, 42, and 52, respectively, and supply power to the loads 33, 43, and 53, respectively.

[0038] In the standby step of step 26 (S26), since the output of each generator has not yet reached the rated output, the process waits for a predetermined time and then returns to the generator operating state acquisition step of step 23 (S23).

[0039] Next, as a modified example of the control method for a DC microgrid, a control method for a DC microgrid in which priority is assigned to loads will be described. That is, instead of waiting until the output power of each generator becomes equal to or greater than the total power of all loads, the process of supplying power sequentially from the load with the highest priority will be described based on the flowchart in Figure 6, focusing on the differences from the flowchart in Figure 5.

[0040] 7A and 7B show an example in which priorities are assigned to the loads 33, 43, and 53 of the DC microgrid 1. Here, the load 43 (load capacity 200) has the first priority, the load 33 (load capacity 300) has the second priority, and the load 53 (load capacity 100) has the third priority.

[0041] As shown in FIG. 7B , the loads (L1) up to the first priority level are loads 43 (load capacity 200). The loads (L2) up to the second priority level are loads 43 (load capacity 200) + load 33 (load capacity 300), for a total load capacity of 500. The loads (L3) up to the third priority level are loads 43 (load capacity 200) + load 33 (load capacity 300) + load 53 (load capacity 100), for a total load capacity of 600. Therefore, for example, if the output capacity of each generator 35, 45, 55 is between 500 and 600, the equipment control devices 41, 31 output connection commands to switches 42 and 32 to supply power to the loads (L2) up to the second priority level, i.e., loads 43 and 33.

[0042] This DC microgrid control method includes the following steps 31 (S31) to 37 (S37). Note that the processing contents of steps 31 (S31) to 33 (S33) are the same as steps 21 (S21) to 23 (S23) in Fig. 5, and therefore a description thereof will be omitted.

[0043] In step 34 (S34), a comparison step of available output power and load power corresponding to priority, each device control device 31, 41, 51 compares the total available output power (P) of each generator 35, 45, 55 with the total load power (L1 to Ln) corresponding to the priority (1 to n). A priority n is determined such that the relationship P≧Ln holds.

[0044] In step 35 (S35), a switch connection step, a connection command is output to the switches of the loads corresponding to priority levels 1 to n, and power is supplied to the loads corresponding to priority levels 1 to n. For example, in FIGS. 7A and 7B, a comparison of the total output power (P) of each generator 35, 45, and 55 with the total load power (L1 to Ln) corresponding to the priorities (1 to n) shows that the relationship P≧L2 holds. In this case, the equipment control device 41 first outputs a connection command to the switch 42, supplying power to the load 43 with the first priority. Furthermore, the equipment control device 31 outputs a connection command to the switch 32, supplying power to the load 33 with the second priority. Note that in this switch connection step, no start command is output to the switch corresponding to a load with a higher priority that has already been started.

[0045] In step 36 (S36), a full load power supply confirmation step, it is confirmed whether a connection command has been output to the switches corresponding to all the loads, i.e., whether power has been supplied to all the loads. If power has been supplied to all the loads, the process ends, and if there is a load to which power has not yet been supplied, the process proceeds to step 37 (S37).

[0046] In the standby step of step 37 (S37), since the output of each generator has not yet reached the rated output, the process waits for a predetermined time and then returns to the generator operating state acquisition step of step 33 (S33).

[0047] Here, the processing of step 34 (S34) and step 35 (S35) will be summarized using the equipment control device 31 of consumer 3 as an example. The equipment control device 31 compares the power amounts of prioritized loads 33, 43, 53 of consumers 3, 4, 5 with the operating states of generators 45, 55 of consumers 4, 5 acquired via the communication unit 64 and the total available power output calculated from the operating state of generator 35 of consumer 3, and if load 33 of consumer 3 corresponds to a load with a high priority within the range of the total available power output, it connects the load switch 32 of consumer 3 and supplies power to load 33. In the case of the equipment control device 41 of consumer 4, if load 43 of consumer 4 corresponds to a load with a high priority within the range of the total available power output, it connects the load switch 42 of consumer 4 and supplies power to load 43. In addition, in the case of the equipment control device 51 of the consumer 5, if the load 53 of the consumer 5 is a load with a high priority within the range of the total outputtable power amount, the load switch 52 of the consumer 5 is connected and power is supplied to the load 53.

[0048] As described above, the DC microgrid and the control method for the DC microgrid according to the first embodiment can realize a DC microgrid that enables a black start and stable power supply sharing with a simple configuration.

[0049] Second Embodiment In a DC microgrid according to a second embodiment, one consumer is provided with a photovoltaic power generator, a storage battery, and a load, and the other two consumers are provided with only loads.

[0050] A DC microgrid according to the second embodiment will be described, focusing on the differences from the first embodiment, based on Fig. 9, which is a schematic configuration diagram of the DC microgrid, and Figs. 10 to 12, which are operational flow diagrams for black start. In the drawings of the second embodiment, parts that are the same as or equivalent to those of the first embodiment are given the same reference numerals. Note that, to distinguish from the first embodiment, the components are referred to as a DC microgrid 100, consumers 103, 104, and 105, and device control devices 131, 141, and 151. In the description, a solar power generator will be referred to as a PV power generator.

[0051] First, the overall configuration and operation of the DC microgrid 100 according to the second embodiment will be described with reference to Fig. 9. The DC microgrid 100 is connected to the power grid 200 during normal operation, and is disconnected and operates in an islanded state if an accident or the like occurs on the power grid 200 side.

[0052] The DC microgrid 100 is composed of a distribution line 2 and consumers 103, 104, and 105. The consumers 103, 104, and 105 are connected via the distribution line 2. Note that the configuration in Fig. 9 is an example, and some or all of the consumers may have the same configuration as the consumer 103, i.e., a configuration including a PV generator and a storage battery.

[0053] The consumer 103 includes an equipment control device 131, a load switch 32, a load 33, a PV converter 36 as a generator converter, a PV generator 37 as a generator, a battery converter 38, and a battery 39. The equipment control device 131, the load switch 32, the PV converter 36, and the battery converter 38 are connected by a consumer-interior distribution line 23. The consumer-interior distribution line 23 is connected to a distribution line 2. Note that in FIG. 9 , the PV generator is referred to as PV. To simplify the explanation, for example, the consumer-interior distribution line 23 will be referred to as the consumer-interior distribution line 23, and the load switch 32 will be referred to as the switch 32, as appropriate.

[0054] The switch 32 controls the power supply to the load 33 by closing or opening it. The PV converter 36 supplies power supplied from the PV generator 37 to the home distribution line 23. The PV converter 36 can also store power supplied from the home distribution line 23 in a storage battery 39. The appliance control device 131 monitors and controls the status of each appliance in the consumer 103 (i.e., the switch 32, the load 33, the PV converter 36, the PV generator 37, the storage battery converter 38, and the storage battery 39).

[0055] The consumer 104 includes an appliance control device 141, a switch 42, and a load 43. The appliance control device 141 and the switch 42 are connected by a home power distribution line 24. The home power distribution line 24 is connected to the power distribution line 2. The appliance control device 141, the switch 42, and the load 43 have the same functions as the respective appliances of the consumer 103 (the appliance control device 131, the switch 32, and the load 33).

[0056] The consumer 105 includes an appliance control device 151, a switch 52, and a load 53. The appliance control device 151 and the switch 52 are connected by a home power distribution line 25. The home power distribution line 25 is connected to a power distribution line 2. The appliance control device 151, the switch 52, and the load 53 have the same functions as the respective appliances of the consumer 103 (the appliance control device 131, the switch 32, and the load 33).

[0057] The home distribution line 23 is connected to the consumer 104 and the consumer 105 via the distribution line 2. The appliance control device 131 of the consumer 103 is also connected to the appliance control device 141 of the consumer 104 and the appliance control device 151 of the consumer 105 via the communication network 21. The appliance control devices 131, 141, and 151 transmit operation information via the communication network 21 to grasp the operating status of the appliances in each consumer.

[0058] Next, the configurations and functions of the equipment control devices 131, 141, and 151 will be described with reference to FIG. 2 , focusing on the differences from the first embodiment. The equipment control device 131 includes a monitoring unit 61, a determination unit 62, a command unit 63, and a communication unit 64. The monitoring unit 61 of the equipment control device 131 acquires an operation status signal of the PV generator 37 output from the PV converter 36 and an operation status signal of the storage battery 39 output from the storage battery converter 38, and grasps the operation status of the PV generator 37 and the operation status of the storage battery 39. The operation status of the PV generator 37 and the operation status of the storage battery 39 are transmitted to and shared with the equipment control device 141 of the consumer 104 and the equipment control device 151 of the consumer 105 via the communication unit 64 and the communication network 21. As a result, the equipment control devices 131, 141, and 151 share the operation status of the PV generator 37 and the operation status of the storage battery 39 of the DC microgrid 100.

[0059] The determination unit 62 of the equipment control device 131 determines whether to execute the processing of the power outage flow ( FIG. 3 ) described in the first embodiment and the black start flow ( FIGS. 10 and 11 ) described later. In the black start flow ( FIGS. 10 and 11 ), the amount of suppliable power that can be determined from the operating state of the PV generator 37 and the operating state of the storage battery 39 in the DC microgrid 100 is compared with the total amount of power of all loads (loads 33, 43, and 53) in the DC microgrid 100, and determines whether to connect the switch 32 in the consumer 103, i.e., whether to supply power to the load 33. The determination unit 62 of the equipment control device 141 and the determination unit 62 of the equipment control device 151 also perform similar determinations.

[0060] Based on instructions from the determination unit 62, the command unit 63 of the equipment control device 131 outputs start-up commands to the PV converter 36 and the storage battery converter 38 in the consumer 103 that are required to execute the power outage flow and the black start flow, and a connection or opening command to the switch 32. Note that the command unit 63 of the equipment control device 141 and the command unit 63 of the equipment control device 151 similarly output connection or opening commands to the switch 42 and the switch 52, respectively.

[0061] The overall operation of the DC microgrid 100 in the second embodiment will now be described. The basic operation when the distribution line 2 loses voltage due to an accident or other reason is the same as in the first embodiment, but the startup procedure from a power outage differs. Basically, the switches 32, 42, and 52 are connected only after the total output power of the activated PV generator 37 and storage battery 39 in the DC microgrid 100 exceeds the total power of the loads 33, 43, and 53. However, because the output power of the PV generator 37 varies depending on weather conditions such as the amount of solar radiation, the total output power may fall below the total load power. In this case, the voltage of the distribution line 2 may drop, causing the PV converter 36 and storage battery converter 38 to shut down due to low voltage, potentially resulting in a total power outage in the DC microgrid 100. For this reason, the black start flow ( Figures 10 to 12 ) does not consider the operating state of the PV generator 37, which generates unstable power, but only considers the operating state of the storage battery 39, which can output stable power, and compares this with the full load power.

[0062] If the PV converter 36 is in a fault state due to an accident or the like, the PV converter 36 is automatically started up using the power generated by the PV generator 37 by performing a fault recovery operation. On the other hand, if the home distribution line 23 has no voltage due to a lack of generated power or the like, the PV converter 36 detects that the amount of solar radiation has recovered and the power generated by the PV generator 37 is equal to or greater than the power required for the PV converter 36 to start up, and then starts up automatically. When the PV converter 36 starts up, power is supplied to the home distribution line 23 and the distribution line 2.

[0063] The operation of establishing the distribution line voltage performed by the consumer 103 will now be described. When the DC microgrid 100 is in a power outage state, the distribution line 2 and the home distribution lines 23, 24, and 25 are voltageless. From this state, the battery converter 38 is started up and CV control is performed on the home distribution line 23, thereby establishing the voltage of the distribution line 2. In order for power to be supplied from the home distribution lines 23, 24, and 25 in the DC microgrid 100 to each of the device control devices 131, 141, and 151 and for them to operate, the battery 39 needs to be able to output power greater than the total power consumption of the device control devices 131, 141, and 151.

[0064] A case will be described in which an operator manually establishes the voltage of the distribution line 2 regardless of the time of day, such as daytime or nighttime. The operator manually starts up the storage battery 39 and the storage battery converter 38 to supply power to the home distribution line 23. It is assumed that the power initially supplied to the device control device 131 is secured separately and connected by the operator. When the storage battery converter 38 and the storage battery 39 are started up, power is supplied to the home distribution line 23, and the voltage of the distribution line 2 and the home distribution lines 23, 24, and 25 is established. As a result, the device control device 141 of the consumer 104 is supplied with power from the home distribution line 24, and the device control device 151 of the consumer 105 is supplied with power from the home distribution line 25. Each of the device control devices 131, 141, and 151 recognizes via the communication network 21 that the storage battery converter 38 of the consumer 103 has completed startup.

[0065] However, when starting up the DC microgrid 100 from a state in which the storage battery 39 is at the end of discharge, the voltage of the distribution line 2 is initially established by the PV converter 36 performing CV control on the home distribution line 23 using the power generated by the PV generator 37, thereby establishing the voltage of the distribution line 2.

[0066] When the startup of the equipment control device 131 of the consumer 103 is complete, the equipment control device 131 starts the black start flow (FIGS. 10 and 11). When the startup of the equipment control device 141 of the consumer 104 and the equipment control device 151 of the consumer 105 is complete, the equipment control devices 141 and 151 start the black start flow (FIG. 12). The equipment control device 131 outputs a startup command to the storage battery converter 38 and performs CV control on the home distribution line 23. At this time, the target voltage of the CV control of the storage battery converter 38 is set lower than the target voltage of the PV converter 36, so that the power output from the PV converter 36 is charged to the storage battery 39 via the storage battery converter 38. When the storage battery converter 38 is charged to a certain SOC (State of Charge) or higher, the equipment control device 131 recognizes that the startup of the storage battery converter 38 is complete. In addition, since it is assumed that the storage battery 39 of the consumer 103 is supplying only the power necessary to start up each equipment control device 131, 141, and 151, by implementing the black start flow, the storage battery converter 38 (storage battery 39) is instructed to start up at rated output.

[0067] The black start of the consumer 103 will be explained using the black start operation flow diagrams of FIGS. 10 and 11. This black start flow includes steps 41 (S41) to 49 (S49). In step 41 (S41), the equipment control device 131 outputs a startup command to the storage battery converter 38. In step 42 (S42), the equipment control device 131 checks whether startup of the storage battery converter 38 has been completed. If startup of the storage battery converter 38 has been completed, the process proceeds to step 43 (S43); if startup has not been completed, the process proceeds to step 44 (S44). In step 44 (S44), the process waits for a predetermined time and then returns to step 42 (S42). In step 43 (S43), the equipment control device 131 checks the operating state of the storage battery 39, i.e., whether the SOC of the storage battery 39 is equal to or greater than a certain value. If the SOC is equal to or greater than the certain value, the process proceeds to step 45 (S45). If the SOC of the storage battery 39 is not equal to or greater than the predetermined value, the process proceeds to step 46 (S46). In step 45 (S45), the equipment control device 131 checks the operating state of the storage battery 39. In step 46 (S46), the storage battery 39 is charged with the output power of the PV generator 37 until the SOC of the storage battery 39 reaches or exceeds the predetermined value, and then the process returns to step 43 (S43). In step 47 (S47), the equipment control device 131 compares the total outputtable power (P) of the storage battery 39 with the total load power (L) of each load 33, 43, 53. If P≧L, the process proceeds to step 48 (S48), and if P<L, the process proceeds to step 49 (S49). In step 48 (S48), the equipment control device 131 closes the switch 32 to supply power to the load 33. In step 49 (S49), the process waits for a predetermined time and then returns to step 47 (S47). The constant value of SOC described in step 43 (S43) is set in consideration of the total value of the load power.

[0068] In the explanation of the black start of the consumer 103, the case where the storage battery 39 is charged when its SOC is below a certain value was considered, and the output power of the PV converter 36 (PV generator 37) was not taken into consideration. However, if the PV generator 37 is generating power during the day, in step 45 (S45), the equipment control device 131 also checks the operating status of the PV generator 37. In addition, in step 47 (S47), the equipment control device 131 also includes the output power of the PV generator 37 in the total available output power in the DC microgrid 100.

[0069] The black start of the consumers 104 and 105 will be explained using the black start flow of FIG. 12 , with the consumer 104 as a representative. This black start flow includes steps 51 (S51) to 54 (S54). In step 51 (S51), the appliance control device 141 acquires the operating status of the storage battery 39 of the consumer 103 via the communication network 21. In step 52 (S52), the appliance control device 141 compares the total outputtable power (P) of the storage battery 39 with the total load power (L) of each load 33, 43, and 53. If P≧L, the process proceeds to step 53 (S53). If P<L, the process proceeds to step 54 (S54). In step 53 (S53), the appliance control device 141 closes the switch 42 and supplies power to the load 43. In step 54 (S54), the process waits for a predetermined time and then returns to step 51 (S51). In addition, the consumer 105 also performs a black start process in the same way, and the equipment control device 151 closes the switch 52 to supply power to the load 53 .

[0070] In the explanation of the black start of the consumer 104, the nighttime case was considered and the output power of the PV converter 36 (PV generator 37) was not taken into consideration, but if the PV generator is generating power during the day, in step 51 (S51), the equipment control device 141 also acquires the operating status of the PV generator 37. In addition, in step 52 (S52), the equipment control device 141 also includes the output potential power of the PV generator 37 in the total output potential power.

[0071] In the above description of the second embodiment, when the outputtable power of the PV generator 37 and the storage battery 39 in the DC microgrid 100 exceeds the total value of the power of all the loads (loads 33, 43, 53), all the switches (switches 32, 42, 52) in the DC microgrid 100 are connected to supply power to all the loads (loads 33, 43, 53). However, as described in the first embodiment, power can also be supplied to the loads with the highest priority.

[0072] The operation when loads are prioritized will be described. The equipment control device 131 of the consumer 103 compares the amounts of power of the prioritized loads 33, 43, and 53 of the consumers 103, 104, and 105 with the total available power output calculated from the operating state of the PV generator 37 and the operating state of the storage battery 39. If the load 33 of the consumer 103 corresponds to a load with a high priority within the range of the total available power output, the load control device 131 connects the load switch 32 of the consumer 103 and supplies power to the load 33. The equipment control device 141 of the consumer 104 compares the amounts of power of the prioritized loads 33, 43, and 53 with the total available power output calculated from the operating state of the PV generator 37 and the operating state of the storage battery 39. If the load 43 of the consumer 104 corresponds to a load with a high priority within the range of the total available power output, the load control device 141 connects the load switch 42 of the consumer 104 and supplies power to the load 43. In addition, the equipment control device 151 of the consumer 105 compares the power amounts of the prioritized loads 33, 43, and 53 with the total available output power amount calculated from the operating status of the PV generator 37 and the operating status of the storage battery 39, and if the load 53 of the consumer 105 is a load with a high priority within the range of the total available output power amount, the load switch 52 of the consumer 105 is connected and power is supplied to the load 53.

[0073] When distinguishing between customers and constituent devices without using reference numerals, they will be described as follows: Customer 103 will be described as the first customer, and customer 104 (105) will be described as the second customer. Home distribution line 23 will be described as the first home distribution line, and home distribution line 24 (25) will be described as the second home distribution line. Equipment control device 131 will be described as the first equipment control device, and equipment control device 141 (151) will be described as the second equipment control device. Load switch 32 will be described as the first load switch, and load switch 42 (52) will be described as the second load switch. Load 33 will be described as the first load, and load 43 (53) will be described as the second load. The judgment unit 62 of the equipment control device 131 of the customer 103 will be referred to as the first judgment unit, the command unit 63 as the first command unit, and the communication unit 64 as the first communication unit, and the judgment unit 62 of the equipment control device 141 (151) of the customer 104 will be referred to as the second judgment unit, the command unit 63 as the second command unit, and the communication unit 64 as the second communication unit.

[0074] In the above description of the second embodiment, a solar power generator is used as the energy generating power source for the consumer, but a wind power generator, a gas turbine power generator, a fuel cell, etc. may also be used.

[0075] As described above, the DC microgrid is configured such that one consumer has a PV generator, a storage battery, and a load, and the other two consumers have only loads. According to the DC microgrid of the second embodiment, it is possible to realize a DC microgrid that enables black start and stable power supply sharing with a simple configuration.

[0076] An example of hardware for the device control device according to the first and second embodiments will now be described with reference to FIG. 8 , using the device control device 31 as a representative example. The device control device 31 is composed of a processor 1000 and a storage device 1001. The storage device 1001 includes a volatile storage device such as a random access memory and a non-volatile auxiliary storage device such as a flash memory, both not shown. Alternatively, a hard disk auxiliary storage device may be provided instead of the flash memory. The processor 1000 executes a program input from the storage device 1001. In this case, the program is input to the processor 1000 from the auxiliary storage device via the volatile storage device. The processor 1000 may output data such as calculation results to the volatile storage device of the storage device 1001, or may store the data in the auxiliary storage device via the volatile storage device.

[0077] Although various exemplary embodiments and examples are described in this disclosure, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are anticipated within the scope of the technology disclosed in this disclosure. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment.

[0078] 1 DC microgrid, 2 distribution line, 3, 4, 5, 103, 104, 105 consumer, 21 communication network, 31, 41, 51, 131, 141, 151 equipment control device, 23, 24, 25 consumer distribution line, 32, 42, 52 load switch, 33, 43, 53 load, 34, 44, 54 generator converter, 35, 45, 55 generator, 36 PV converter, 37 PV generator, 38 storage battery converter, 39 storage battery, 61 monitoring unit, 62 judgment unit, 63 command unit, 64 communication unit, 200 power system, 1000 processor, 1001 storage device.

Claims

1. A DC microgrid connected to a power system in which two or more consumers are connected via distribution lines, each of the consumers being composed of a generator converter that supplies power from a generator to a distribution line within the consumer's premises, a load switch that connects or disconnects a load to the distribution line within the consumer's premises, and an equipment control device that controls the generator converter and the load switch, and each of the equipment control devices grasps the operating status of each of the generators via a communication network, in which when a generator is disconnected from the power system and the load is separated, each of the equipment control devices grasps the operating status of each of the generators and connects the load switch of each of the consumers based on the operating status to supply power to the load.

2. The equipment control device of claim 1 comprises: a monitoring unit that monitors the operating status of the generator; a communication unit that transmits the operating status of the generator to the equipment control device of the other consumer; a judgment unit that compares a total available output power amount calculated from the operating status of the generator of the other consumer acquired by the communication unit and the operating status of the generator of the consumer itself with a total power amount to the load and judges whether or not power can be supplied to the load; and a command unit that issues a start-up command to the generator converter of the consumer itself and a connection command or an opening command to the load switch.

3. The DC microgrid of claim 2, wherein the equipment control device compares the total electric energy of the loads of each of the consumers with a total available output electric energy calculated from the operating states of the generators of the other consumers and the operating state of the generator of the consumer itself obtained via the communication unit, and when the total available output electric energy becomes equal to or greater than the total electric energy of the loads, connects the load switch of the consumer itself to supply electric power to the load.

4. The DC microgrid of claim 2, wherein the equipment control device compares the amount of power of the prioritized loads of each of the consumers with a total available output power calculated from the operating states of the generators of the other consumers and the operating state of the generator of the consumer itself obtained via the communication unit, and connects the load switches of the consumers in order of the loads with the highest priority within the range of the total available output power, thereby supplying power to the loads.

5. A DC microgrid connected to a power system, comprising one or more first consumers connected to the distribution line, the first consumers including a generator converter supplying power from a generator to a distribution line in a first consumer, a battery converter supplying power from a battery to the distribution line in the first consumer or storing power from the distribution line in the first consumer in the battery, a first load switch connecting or disconnecting a first load to the distribution line in the first consumer, and a first equipment control device controlling the generator converter, the battery converter, and the first load switch, and one or more second consumers connected via the distribution line, the second consumers including a second load switch connecting or disconnecting a second load to a distribution line in a second consumer, and a second equipment control device controlling the second load switch, the first equipment control device and the second equipment control device grasping an operating state of the generator and an operating state of the battery via a communication network, When the first load and the second load are disconnected from the power grid, the first equipment control device and the second equipment control device grasp the operating state of the generator and the operating state of the storage battery, and connect the first load switch of the first consumer and the second load switch of the second consumer based on the operating state and the operating state to supply power to the first load and the second load.

6. The first equipment control device comprises: a monitoring unit that monitors the operating state of the generator and the operating state of the storage battery; a first communication unit that transmits the operating state of the generator and the operating state of the storage battery to the second equipment control device of the second consumer; a first determination unit that compares a total available output power amount calculated from the operating state of the generator and the operating state of the storage battery with a total amount of power of the first load and the second load, and determines whether or not power can be supplied to the first load; and a first command unit that issues a start command to the generator converter and the storage battery converter of the first consumer, and a connection command or an opening command to the first load switch; and the second equipment control device comprises: a second communication unit that receives the operating state of the generator and the operating state of the storage battery of the first consumer from the first equipment control device; a second determination unit that compares the total available output power amount calculated from the operating state of the generator and the operating state of the storage battery with a total amount of power of the first load and the second load, and determines whether or not power can be supplied to the second load; The DC microgrid according to claim 5 , further comprising: a second command unit that issues a connection command or an opening command to the second load switch.

7. The DC microgrid described in claim 6, wherein the first equipment control device compares a total amount of electric power of the first load of the first consumer and the second load of the second consumer with a total available output electric power calculated from the operating state of the generator of the first consumer and the operating state of the storage battery, and when the total available output electric power becomes equal to or greater than the total amount of electric power of the first load and the second load, connects the first load switch of the first consumer to supply electric power to the first load; and the second equipment control device compares a total amount of electric power of the first load of the first consumer and the second load of the second consumer with a total available output electric power calculated from the operating state of the generator of the first consumer and the operating state of the storage battery, and when the total available output electric power becomes equal to or greater than the total amount of electric power of the first load and the second load, connects the second load switch of the second consumer to supply electric power to the second load.

8. The DC microgrid described in claim 6, wherein the first equipment control device compares the amount of power of the prioritized first load and the prioritized second load of the first consumer and the second consumer with a total available output power calculated from the operating state of the generator of the first consumer and the operating state of the storage battery, and connects the first load switch of the first load with a higher priority within the range of the total available output power, and supplies power to the first load; and the second equipment control device compares the amount of power of the prioritized first load and the prioritized second load of the first consumer and the second consumer with a total available output power calculated from the operating state of the generator of the first consumer and the operating state of the storage battery, and connects the second load switch of the second load with a higher priority within the range of the total available output power, and supplies power to the second load.

9. In a DC microgrid connected to a power system, where consumers each composed of a generator converter that supplies power from a generator to a distribution line within a consumer's premises, a load switch that connects or disconnects a load to the distribution line within the consumer's premises, and an equipment control device that controls the generator converter and the load switch are connected via two or more distribution lines, and each of the equipment control devices grasps the operating state of each of the generators via a communication network, when the consumer is disconnected from the power system and the load is separated, a distribution line voltage establishment step is performed in which one of the equipment control devices is started up, a start-up command is output to the generator converter, the generator is started up, and power is supplied to the distribution line within the consumer's premises to establish the voltage of the distribution line, a generator converter start-up step in which each of the equipment control devices outputs a start-up command to each of the generator converters and starts up each of the generators, and a generator operating state acquisition step in which each of the equipment control devices acquires the operating states of the generators of other consumers via the communication network. A DC microgrid control method comprising: an output power and load power comparison step in which each of the equipment control devices compares a total value (P) of the output power of each of the generators with a total value (L) of the load power of each of the loads, and proceeds to a switch connection step if P≧L, and proceeds to a standby step if P<L; in the switch connection step, each of the equipment control devices outputs a connection command to each of the load switches and supplies power to each of the loads; and in the standby step, the device control devices wait for a predetermined time and then return to the generator operating status acquisition step.

10. In a DC microgrid connected to a power system, where a consumer is connected via two or more distribution lines and includes a generator converter that supplies power from a generator to a distribution line within the consumer's premises, a load switch that connects or disconnects a load to the distribution line within the consumer's premises, and an equipment control device that controls the generator converter and the load switch, and where each of the equipment control devices grasps the operating state of each of the generators via a communication network, when the consumer is disconnected from the power system and the load is separated, a distribution line voltage establishment step is performed in which one of the equipment control devices is started up, a start-up command is output to the generator converter, the generator is started up, and power is supplied to the distribution line within the consumer's premises to establish the voltage of the distribution line; a generator converter start-up step in which each of the equipment control devices outputs a start-up command to each of the generator converters and starts up each of the generators; and a generator operating state acquisition step in which each of the equipment control devices acquires the operating states of the generators of other consumers via the communication network. a load power supply status confirmation step of confirming whether or not power has been supplied to all of the loads, and if power has been supplied to all of the loads, the processing is terminated, and if power has not been supplied to any of the loads, the processing proceeds to a standby step, and in the standby step ...

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