JP7425674B2 - Command device, microgrid system, command method - Google Patents

Description

The present invention relates to a command device, a microgrid system, and a command method.

In order to realize the energy local production and local consumption model, it is necessary to construct a so-called microgrid, which is equipped with power generation equipment, power storage equipment, consumption equipment, and a power distribution system that connects them. Today's microgrids do not have to be completely separated from the power grid, but instead have the ability to buy and sell surplus or insufficient power that cannot be accommodated within the microgrid through the power grid, thereby reducing total energy costs and renewable energy rates. It is desirable to improve. Traditionally, power within microgrids has historically been provided by alternating current due to the ease of voltage conversion. In controlling AC grids, it is necessary to control not only voltage and current but also frequency and phase, and accurate and rapid control has been difficult. Since renewable energy power sources and power storage equipment operate on DC, it is inherently advantageous for microgrids equipped with many such equipment to operate on DC because DC-AC conversion losses can be reduced. Recent advances in power electronics have made it easier to supply power using direct current. For example, in some data centers, DC power supply of about 400V is implemented.

However, in general equipment, AC 100V to 200V is used in Japan, and a separate AC converter is required to connect to the above-mentioned DC power line, resulting in conversion loss. In addition, standards for voltage, connection plugs, and outlets are not standardized around the world, which significantly impairs convenience. Furthermore, when designing a universal device that is compatible with the various voltage standards mentioned above, the power supply circuit inside the device must be compatible with the various voltage standards, which is disadvantageous in terms of loss in the power supply circuit. Patent Document 1 describes a DC power supply outlet having a voltage converter that converts a voltage supplied from a power supply source into a voltage of a specified value, and a female to which the voltage converted by the voltage converter is applied. information receiving means for receiving a plurality of device-side efficiency information representing power conversion efficiency of a device having a terminal and a DC power supply plug inserted into the female terminal from the DC power supply plug; and a power conversion unit for the DC power supply outlet. Based on an information storage means for storing a plurality of outlet side efficiency information representing efficiency, a plurality of device side efficiency information received by the information receiving means, and a plurality of outlet side efficiency information stored in the information storage means. Disclosed is a DC power supply outlet, comprising: voltage value designation means for designating, to the voltage conversion unit, a designated value for reducing the power supplied from the power supply source to the voltage conversion unit. has been done.

Japanese Patent Application Publication No. 2011-253665

In the invention described in Patent Document 1, there is room for efficiency improvement.

A command device according to a first aspect of the present invention is a command device that controls a master connected to a power system through which alternating current power flows and includes a power conversion device, the master having one or more master devices and wiring through which direct current power flows. The master device converts the power of the DC bus and supplies it to one or more slave devices via equipment wiring, and the master device controls at least one of the current and voltage of the DC bus. and a master control unit that causes the master device to control at least one of the current and voltage of the device wiring.
A microgrid system according to a second aspect of the present invention includes a command device, a main trunk connected to an electric power system through which AC power flows, one or more master devices, and one or more slave devices. The master device is connected to the one or more master devices by a DC bus, which is a wiring through which DC power flows, and the master device is connected to one or more slave devices by equipment wiring, which is a wiring through which DC power flows. The device includes a master control unit that causes the master device to control at least one of the current and voltage of the DC bus, and a master control unit that causes the master device to control at least one of the current and voltage of the device wiring, Each of the devices includes a converter for converting the voltage of DC power.
A command method according to a third aspect of the present invention is a command method executed by a command device that controls a master connected to a power system through which AC power flows and is equipped with a power conversion device, the master having one or more master devices. The master device converts the power of the DC bus and supplies it to one or more slave devices via device wiring, and the master device receives the current and voltage of the DC bus. and causing the master device to control at least one of a current and a voltage of the device wiring.

According to the present invention, power usage efficiency can be increased.

A diagram showing the configuration of a microgrid system in the first embodiment Block diagram showing the configuration of the command device Diagram showing master and slave configuration Diagram showing an example of a time series supply and demand table Diagram showing an example of an efficiency table Time chart showing the operation of the microgrid system A diagram showing the configuration of a microgrid system in a second embodiment A diagram showing the configuration of a command device in a second embodiment A diagram showing the configuration of a command device in a third embodiment Time chart showing the operation of the change handling section A diagram showing the configuration of a command device in the fourth embodiment Time chart showing the operation of the microgrid system when the abnormality detection unit detects an abnormality in the power system A diagram showing the configuration of a command device in a fifth embodiment Time chart showing the operation of the microgrid system when a surplus of electricity is detected Diagram showing the configuration of a microgrid system in a seventh embodiment Diagram showing the configuration of the m-th master

-First embodiment-
A first embodiment of the microgrid system will be described below with reference to FIGS. 1 to 6.

FIG. 1 is a diagram showing a microgrid system 1 according to the present invention. In FIG. 1, solid lines indicate the flow of power, and broken lines indicate the flow of information. The microgrid system 1 communicates with other grids 92 and power exchanges 91 via an external network 90. Furthermore, the microgrid system 1 is also electrically connected to another grid 92 via the power receiving point 9. Although FIG. 1 shows power transmission from another grid 92 to the microgrid system 1, power transmission is also performed in the opposite direction, that is, from the microgrid system 1 to the other grid 92. Note that, hereinafter, the area to the left of the power receiving point 9 in the drawing will be referred to as the "power system".

The microgrid system 1 includes a command device 2, a main trunk 3, a master device M, and a slave device S. In the following, the master device will be referred to as a "master" and the slave device will be referred to as a "slave." Master M is a general term for first master M1, second master M2, . . . , Nth master Mn. Slave S is a general term for the 1a-th slave S1a, the 1b-th slave S1b, . . . the Nn-th slave SNn. The flow of power in the microgrid system 1 is in the form of a tree in which the main trunk 3 is the apex node, each master M is a child node, and each slave S is a grandchild node. However, power may flow from the slave S to the master 3, or from the master 3 to the slave S. One or more slaves S are connected to each master M. In the following, a slave S connected to a certain master M is also referred to as a slave S existing under a certain master M.

The slave S is a device that operates by consuming power, or a device that generates power. Each slave S has an operation plan made in advance, and each slave S has a demand power that is the required power, a supply power that is the supplied power (hereinafter referred to as "supply and demand power"), and the time. Information indicating relationships is stored.

Hereinafter, the slave S that generates electric power will also be referred to as a "power generation slave device." The power generated by the power generation slave device may be used by other slaves S under the same master M, or may be used by slave S under another master M, or may be used by the master M. 3, it may be converted into AC power and output to the power grid. For example, when the 1b slave S1b is a power generation slave device, the power generated by the 1b slave S1b may be used by the 1a slave S1a connected under the same first master M1, or by another master. It may be used by the nnth slave Snn connected under the nth master Mn.

FIG. 2 is a block diagram showing the configuration of the command device 2. As shown in FIG. The command device 2 includes a master control section 21 , a master control section 22 , a command device communication section 23 , and a command device storage section 29 . The main control unit 21 and the master control unit 22 are realized, for example, by a CPU, which is a central processing unit, loading a program stored in a ROM, which is a read-only storage device, into a RAM and executing the program. The operations of the main control section 21 and the master control section 22 will be described later.

The main control unit 21 calculates the voltage and current (hereinafter referred to as "voltage current") of the DC bus 4 so as to satisfy the supply and demand power of each slave S at the next control time. Note that voltage and current control in the DC bus and equipment wiring follows Ohm's law and Kirchhoff's law because this system uses direct current. The product of the sum of the DC resistances and the current flowing through the DC bus and the master serving as the load corresponds to the DC bus voltage at the master and DC bus connection portion. That is, the voltage and current cannot be controlled freely, but are subject to the above-mentioned constraint conditions. Therefore, originally it is only necessary to control either voltage or current, but since the load resistance is not constant and changes depending on the amount of power consumed by the master, Depending on the situation, voltage control and current control may change over time. Here, to simplify the description, the expression "voltage and current control" is used. In this calculation, the voltage and current are determined so that the loss in the power conversion devices built in the master, each master M, and each slave S is minimized. The characteristics of the power conversion device built into the master are known, the characteristics of the power conversion device built into the master M are described in the master efficiency information 293 described later, and the characteristics of the power conversion device built into the slave S are described later. It is recorded in the time series supply and demand table 291. Then, the master control unit 21 notifies the master 3 of the calculated voltage and current, thereby causing the master 3 to control the voltage and current of the DC bus 4 to the calculated value. The master control unit 22 notifies each master M of the voltage and current calculated by the master control unit 21, and causes the master M to control the voltage and current of the device wiring 6.

The command device communication unit 23 included in the command device 2 communicates with the inside and outside of the microgrid system 1 . Specifically, the command device communication unit 23 communicates with the power exchange 91 and other grids 92 via the external network 90, and communicates with the main manager 3 and master M. The command device storage unit 29 is a nonvolatile storage device, such as a flash memory, and stores a time series supply and demand table 291, an efficiency table 292, and master efficiency information 293.

The information stored in the time series supply and demand table 291 includes the power demand and supply of the slave S at each time, the characteristics of the power conversion efficiency of the slave, and the priority. Note that hereinafter, the sum total of power demand and supply at a certain time in the microgrid system 1 will be referred to as "grid connection amount." The information stored in the time series supply and demand table 291 is information collected from each slave S and is updated as needed. The efficiency table 292 and master efficiency information 293 may be information acquired in advance, or may be information acquired from the slave S or master M each time it is needed.

The efficiency table 292 shows a list of conversion efficiencies of power converters. Since conversion efficiency characteristics differ depending on the type and operating conditions of the power converter, the efficiency table 292 stores each characteristic in association with a name. Master efficiency information 293 shows a list of conversion efficiencies of power converters included in each master M. The master efficiency information 293 may be defined using the names of the characteristics in the efficiency table 292, or may be defined using specific numerical values like the efficiency table 292. Specific examples of the time series supply and demand table 291 and the efficiency table 292 will be explained later. Returning to FIG. 1, the explanation will be continued.

The main trunk 3 is a substation equipment that operates according to commands from the command device 2 . The left side of the main trunk 3 in the figure is an AC power area, and the right side of the figure is a DC power area, and the main trunk 3 mutually converts AC power and DC power. The main trunk 3 determines the voltage of DC when converting from AC based on the command from the command device 2 . The AC voltage that the main trunk 3 converts from direct current is a predetermined constant value used in the power system, but this may not be the case depending on the configuration of the power system to which the main trunk 3 connects. It may be configured to be changeable based on. The main trunk 3 is electrically connected to each master M via a DC bus 4.

FIG. 3 is a diagram showing the configuration of master M and slave S. In FIG. 3, the configuration of the first master M1 is shown as a representative of the master M, and the configuration of the 1a-th slave S1a and the 1n-th slave S1n is shown as the slave S. Each master M and each slave S are connected by device wiring 6. The device wiring 6 is a cable that complies with, for example, the USB-PD (Power Delivery) standard, in which a power line and a communication line are integrated.

The device wiring 6 includes a positive power line 6P, a negative power line 6N, a ground line 6G, a communication line 6C, a receptacle 6RE, and a plug 6PU. The positive power line 6P and the negative power line 6N are connected to the ground line 6G via a resistor R having a high resistance value to avoid the risk of electric shock. Note that only one of the positive power line 6P and the negative power line 6N may be used, or the device wiring 6 may not include one of the positive power line 6P and the negative power line 6N. Although the communication line 6C is shown as a single line in FIG. 3, the actual number of lines varies depending on the communication standard and may be communicated using not only one line but multiple lines. Further, the device wiring 6 may not include the communication line 6C. In that case, slave S and master M communicate wirelessly.

Master M includes a power conversion section 51, a signal processing section 52, a communication section 53, and a plurality of semiconductor switches 54. The power conversion unit 51 is a so-called DC-DC converter that converts the voltage of DC power, and operates according to commands from the command device 2. The voltages converted by each master M may be constant or different. To give an example of the voltage, DC 100V is provided to the DC bus 4 connecting the master 3 and master M, the first master M1 steps down the voltage to DC 10V and distributes it to the slave devices under its control, and the second master M2 The voltage is stepped down to 5V DC and distributed to the following slave devices. Note that the master M may be an independent device or may be configured integrally with other devices. For example, a power conditioner included in a solar power generation device or a power storage device may be treated as one of the masters M.

The signal processing section 52 has functions such as setting voltage and current for the power conversion section 51, controlling the semiconductor switch 54, sending and receiving information with the communication section 53, and storing necessary information. These functions may be executed by, for example, a CPU (not shown) provided in the master M by loading a program stored in a ROM (not shown) into a RAM (not shown), or may be realized by a hardware circuit or the like. good.

The communication unit 53 performs communication with the slave S via the receptacle 6RE and the plug 6PU, communication with the signal processing unit 52, and communication with the command device 2. Further, the communication unit 53 may be configured to be connectable to the Internet using a wired or wireless communication line (not shown).

The slave S includes a slave power conversion section 71, a load 72, a slave signal processing section 73, and a slave communication section 74. However, as described later, the slave S may not include the slave power conversion section 71. The slave S communicates with the connected master M, and acquires and supplies power. From the perspective of power transfer, each slave S may only supply power to the master M, may only be supplied with power from the master M, or may both supply power to the master M and master M. It may also be possible to switch the power supply from.

The slave power converter 71 is a so-called DC-DC converter that converts the voltage of DC power, and operates according to instructions from the slave signal processor 73. The slave signal processing section 73 communicates with the master M via the slave communication section 74, and transmits information on the supply and demand power of the slave S at each time to the master M. Then, the slave signal processing section 73 controls the slave power conversion section 71 so that the voltage and current are the same as agreed with the master M. Note that if the slave S does not include the slave power conversion section 71, the slave signal processing section 73 controls the load 72. The slave communication unit 74 is connected to the communication unit 53 of the master M, and communicates with the master M through a communication line 6C included in the device wiring 6.

FIG. 4 is a diagram showing an example of a time-series supply and demand table 291 stored in the command device 2. As shown in FIG. The time-series supply and demand table 291 shown in FIG. 4 stores power supply and demand for each slave S at each time, characteristics of power conversion efficiency, and priority. Specifically, information on different times is stored in the horizontal direction of FIG. 4, and information on different slaves S is stored in the vertical direction.

In the power column, power demand is written as a positive value, and power supply is written as a negative value. The efficiency characteristic column shows the name of the corresponding efficiency characteristic in the efficiency table 292. In the priority column, information on the priority of power supply and demand is written. In the example shown in FIG. 4, the highest priority is given priority "A", and the lowest priority is given priority "C". The information shown in FIG. 4 is updated every time information regarding power supply and demand is acquired from the slave S.

(efficiency table)
FIG. 5 is a diagram showing an example of the efficiency table 292 stored in the command device 2 and the master M. In FIG. 5, information on different characteristics is arranged in the horizontal direction in the drawing, and rank types, which are power ranges, are shown in the vertical direction in the drawing. Efficiency is, for example, the average value of power varying within the same rank. Note that in the example shown in FIG. 5, the power classification is the same regardless of the type of characteristic, but the power that separates the ranks may be different for each type of characteristic.

(Time chart)
FIG. 6 is a time chart showing the operation of the microgrid system 1 in this embodiment. Note that in FIG. 6, the current time is t0, the time interval between control executions is Δt, and steps S301 to S312 are shown, which are processes that target the next control time t0+Δt.

In step S301, the command device 2 performs broadcast communication to inquire of all masters M about the required power at time t0+Δt. In the following step S302, each master M performs broadcast communication to inquire of all the slaves S under its control about the required power at time t0+Δt. In step S303, each slave S replies to the master M with the supply and demand power at time t0+Δt, the name of the efficiency characteristic, and the priority.

In step S304, each master M collects the responses from the slaves S and notifies the command device 2. In step S305, the master control unit 21 of the command device 2 aggregates information such as the supply and demand power at time t0+Δt, determines the voltage and current of the DC bus 4, and notifies the master 3 of the voltage and current of the DC bus 4. Further, the master control unit 22 of the command device 2 notifies each master M of the voltage and current calculated by the master control unit 21, and causes the master M to control the voltage and current of the equipment wiring 6. Furthermore, the command device 2 notifies the power exchange 91 and other grids 92 of the supply and demand power of the microgrid system 1 at time t0+Δt, that is, the amount of grid connection.

In step S306, each master M determines the voltage and current of each device wiring 6 so that the efficiency of the slave power conversion unit 71 is maximized, and notifies each slave S of the voltage and current. In step S307, in each slave S, the slave signal processing section 73 outputs a command to prepare for changing the operation mode to either the slave power conversion section 71 or the load 72. In step S308, each slave S notifies the master M of completion of preparation. In step S309, each master M confirms that it has received notifications of completion of preparation from all slaves S under its control, and notifies command device 2 of completion of preparation.

In step S310, upon confirming that the command device 2 has received the notification of completion of preparation from each master M, it transmits a mode change trigger to all masters M at time t0+Δt. In step S311, each master M sends a change trigger to the slaves S under its control. In step S312, each slave S causes either the slave power converter 71 or the load 72 to change the operation mode immediately upon receiving the change trigger.

By repeatedly executing steps S301 to S312 described above, the microgrid system 1 can set the optimal voltage and current for the DC bus 4 and each device wiring 6 at any control time.

According to the first embodiment described above, the following effects can be obtained.
(1) The command device 2 controls the main trunk 3 that is connected to a power system through which AC power flows and includes a power conversion device. The main trunk 3 is connected to one or more masters M by a DC bus 4, which is a wiring through which DC power flows. The master M converts the power of the DC bus 4 and supplies it to one or more slaves S via the device wiring 6. The command device 2 includes a master control unit 21 that causes the master 3 to control at least one of the current and voltage of the DC bus 4, and a master control unit 22 that causes the master M to control at least one of the current and voltage of the equipment wiring 6. . Therefore, the command device 2 can raise the voltage of the DC bus 4 while lowering the voltage of the device wiring 6 according to the slave S, thereby suppressing the power loss of the microgrid 1 and improving the power usage efficiency. It can be made higher.

(2) Using the supply and demand schedule at time t0+Δt obtained from the slave S at time t0, the master control unit 21 transmits the DC bus to the master 3 based on the power demand and power supply of the slave S at the current time at time t0+Δt. At least one of the current and voltage of No. 4 is controlled (step S310 in FIG. 6). Therefore, the command device 2 can set the voltage and current of the DC bus 4 to the minimum values currently required by each slave S.

(3) The master control unit 21 causes the master 3 to control at least one of the current and voltage of the DC bus 4 based on the supply and demand schedule acquired from the slave S as shown in FIG. Therefore, the command device 2 can notify the outside in advance of the power that the slave S will need in the future, and can secure the power.

(4) The master controller 21 controls the DC bus 4 so that power loss is minimized based on information on the power conversion efficiency of the power conversion devices included in the master 3, each master M, and each slave S. Control at least one of current and voltage.

(5) The microgrid system 1 includes a command device 2, a main trunk 3 connected to a power system through which AC power flows, one or more masters M, and one or more slaves S. The main trunk 3 is connected to one or more masters M by a DC bus 4, which is a wiring through which DC power flows. The master M is connected to one or more slaves S by device wiring 6, which is a wiring through which DC power flows. The command device 2 includes a master control unit 21 that causes the master 3 to control at least one of the current and voltage of the DC bus 4, and a master control unit 22 that causes the master M to control at least one of the current and voltage of the equipment wiring 6. . Each of the masters M includes a power conversion section 51 that converts the voltage of DC power.

(6) The slave S transmits a demand and supply schedule, which is a schedule of future demand and supply regarding electric power of the slave S, to the command device 2 via the master M. Therefore, the command device 2 can control the main trunk 3 using the supply and demand schedule.

(7) The slave S includes a power generation slave device capable of generating power. The power generation slave device can supply power to other slaves S.

(8) The slave S includes a power generation slave device capable of generating power. A master M connected to a power generation slave device can supply power generated by the power generation slave device to a slave S connected to another master M.

(Modification 1)
Communication between master M and slave S may be realized by wireless communication instead of wired communication. Furthermore, the slave S may communicate directly with the command device 2 instead of the master M. In this case, the demand and supply schedule of the slave S is transmitted to the command device 2 without going through the master M.

(Modification 2)
In the first embodiment described above, the voltage and current of the DC bus 4 and the device wiring 6 can be set arbitrarily. However, either the voltage or the current may be fixed. In that case, the operation of the power conversion devices built in the master 3, the master M, and the slave S is controlled so that either the voltage or the current is a fixed value.

-Second embodiment-
A second embodiment of the microgrid system will be described with reference to FIGS. 7 and 8. In the following description, the same components as in the first embodiment are given the same reference numerals, and differences will be mainly explained. Points not particularly described are the same as the first embodiment. This embodiment differs from the first embodiment mainly in that the microgrid system includes a plurality of DC buses with different voltage levels.

FIG. 7 is a diagram showing the configuration of a microgrid system 1A in the second embodiment. However, in FIG. 7, the description of the slave S and the description of the communication lines are omitted for convenience of drawing. The microgrid system 1A further includes a sub-converter 43 in addition to the configuration of the microgrid system 1 in the first embodiment. Furthermore, the microgrid system 1A includes a first DC bus 41 and a second DC bus 42 instead of the DC bus 4. The first master M1 to the m-th master Mm are connected to the first DC bus 41, and the m-th master Mm to the x-th master Mx are connected to the second DC bus 42. That is, the m-th master Mm is connected to both the first DC bus 41 and the second DC bus 42. In the following, the master M connected to two DC buses will also be referred to as a "double-connected master device."

The sub-converter 43 includes a power converter and converts voltage based on a command from the command device 2 . That is, the voltage of the first DC bus 41 and the voltage of the second DC bus 42 are different. Further, the sub-converter 43 mediates communication between the n-th master Mn to the x-th master Mx and the command device 2. The m-th master Mm is capable of supplying power to and acquiring power from both the first DC bus 41 and the second DC bus 42, and the ratio thereof can be set arbitrarily.

FIG. 8 is a diagram showing the configuration of a command device 2A in the second embodiment. The command device 2A includes a ratio setting section 24 and a sub-converter setting section 25 in addition to the configuration in the first embodiment. In this embodiment, the main control unit 21 calculates the voltage of each DC bus 4 on the premise that two types of voltages of the DC bus 4 can be set. At this time, the main control unit 21 also refers to information in an efficiency table (not shown) regarding the sub converter 43. The ratio setting unit 24 sets the ratio of the power that the m-th master Mm obtains from the first DC bus 41 and the second DC bus 42 or the ratio of the power that the m-th master Mm outputs to the first DC bus 41 and the second DC bus 42. It is determined and notified to the m-th master Mm.

The sub-converter setting section 25 outputs a command related to power conversion to the sub-converter 43 based on the calculation result of the main control section 21 . For example, the sub-converter setting unit 25 instructs the sub-converter 43 to use the 40V power of the first DC bus 41 to supply 20V to the second DC bus 42.

According to the second embodiment described above, the following effects can be obtained.
(9) The DC bus 4 includes a first DC bus 41 and a second DC bus 42 having different voltage levels. A sub-converter 43 including a transformer capable of changing DC voltage is connected to the first DC bus 41 and the second DC bus 42 . At least one of the masters M, the m-th master Mm, is a dual-connection master device connected to the first DC bus 41 and the second DC bus 42. The command device 2A has a ratio setting unit 24 that specifies the ratio of power output or power input to the first DC bus 41 and the second DC bus 42 for both connected master devices, and a voltage control unit 24 for the sub converter 43. It also includes a sub-converter setting section 25 that outputs instructions regarding change processing. Therefore, the command device 2 can set two DC bus voltages, and can arbitrarily set the power connection of the m-th master Mm to the first DC bus 41 and the second DC bus 42, resulting in higher efficiency. You can set the DC bus voltage as follows.

-Third embodiment-
A third embodiment of the microgrid system will be described with reference to FIGS. 9 and 10. In the following description, the same components as in the first embodiment are given the same reference numerals, and differences will be mainly explained. Points not particularly described are the same as the first embodiment. This embodiment differs from the first embodiment mainly in that changes in power demand and supply in the slave are taken into consideration.

FIG. 9 is a diagram showing the configuration of a command device 2B in the third embodiment. The command device 2B further includes a change handling unit 26 in addition to the configuration of the first embodiment. After the voltage of the second DC bus 42 at a predetermined time in the future is determined, the change handling unit 26 performs a process described later when notified of a schedule change from any slave S.

When the change handling unit 26 is notified that the schedule of any slave S at time t0+Δt has been changed after the process of step S305 in FIG. 6, it executes the process shown in FIG. 10. Note that the processing described below is executed, for example, between step S309 and step S310 in FIG.

In step S321, a certain slave x rewrites the information on the supply and demand power at the next control time t0+Δt and notifies the upper master M of the change. In step S322, the master M who received this notification transmits the change details to the command device 2. In step S323, the change handling unit 26 of the command device 2 calculates the power capacity of the DC bus 4 and the grid connection power amount again based on the change content received from the master M.

In step S324, the change handling unit 26 determines whether the power capacity of the DC bus 4 and the grid connection power amount calculated in step S324 are within the range. For example, if the change in schedule of slave S does not affect the demand or supply of electricity, in other words, even if the change in schedule changes the expected power flowing through the DC bus, it is specified in the specifications of the DC bus. If it is less than the maximum power capacity value and the amount of power connected to the grid is less than the maximum power value contracted with the power distribution company, an affirmative determination is made in this step; otherwise, a negative determination is made. Ru. If the command device 2 determines that the power capacity and grid connection power amount of the DC bus 4 are within the range, the process proceeds to step S326, and at least one of the power capacity of the DC bus 4 and the grid connection power amount is not within the range. If it is determined that this is the case, the process advances to step S325. In step S326, the change handling unit 26 saves the information at time t0+Δt and ends the process shown in FIG. 10.

In step S325, the change handling unit 26 sends a change request to the master M to which slave y, which is one of the slaves S with a lower priority, is connected. This change request is a request for a change necessary for the power capacity of the DC bus 4 and the power amount connected to the grid to be within the range. In step S327, master M sends a request to slave y to change the scheduled power. In step S328, slave y determines whether the power supply and demand schedule can be changed. If it is determined that slave y can be changed, the process proceeds to step S329, and if it is determined that slave y cannot be changed, the process proceeds to step S330.

In step S329, slave y replies to master M that it cannot be changed. In the following step S330, the master M requests the command device 2 to transmit a change request to another slave, and returns to step S325. In step S331, slave y replies to master M that it can be changed. In the following step S332, the master M replies to the command device 2 that the change is possible. In step S333, the command device 2 saves the information of time t0+Δt and ends the process shown in FIG. 10.

According to the third embodiment described above, the following effects can be obtained.

(10) Processing priorities are set in the supply and demand schedule as shown in FIG. The command device 2B includes a change handling unit 26 that causes the slave M to change a supply and demand schedule with a low priority when the supply and demand schedule is changed. Therefore, the command device 2B can deal with changes in the supply and demand schedule that occur after the schedule is set.

-Fourth embodiment-
A fourth embodiment of the microgrid system will be described with reference to FIGS. 11 and 12. In the following description, the same components as in the first embodiment are given the same reference numerals, and differences will be mainly explained. Points not particularly described are the same as the first embodiment. This embodiment differs from the first embodiment mainly in that the connection with the power system is cut off.

FIG. 11 is a diagram showing the configuration of a command device 2C in the fourth embodiment. The command device 2C further includes an abnormality detection section 27 and an independent transition section 28 in addition to the configuration of the first embodiment. The abnormality detection unit 27 has a function of detecting an abnormality in the power system. This function detects, for example, a disconnection in the power system connected to the power receiving point 9 or a failure at the power receiving point 9. Alternatively, an abnormality in the power system may be received through communication from, for example, the power exchange 91 or another grid 92 via the external network 90 shown in FIG. When the command device 2 detects an abnormality in the power system, the independent transition unit 28 performs processing.

FIG. 12 is a time chart showing the operation of the microgrid system 1 when the abnormality detection unit 27 of the command device 2 detects an abnormality in the power system. In step S342, the abnormality detection unit 27 detects an abnormality in the power grid, and the independence transition unit 28 outputs a command to the main trunk 3 to leave the power grid. In step S345, the independence transition unit 28 of the command device 2 first refers to the time-series supply and demand table 291 in order to rewrite the power data at time t0+Δt, which is the control time in the nearest future, and set the grid-connected power amount to zero. Then, a slave S capable of generating electricity is identified, and a request is made to the master M to which that slave is connected to generate electricity at the latest time t0+Δt.

In step S346, the independent transition unit 28 refers to the time-series supply and demand table 291, identifies all slaves S with the lowest priority, and sends a request to the master M to which the slave S is connected. This request is a request for changes necessary to reduce the power balance of the DC bus 4 to zero and reduce the amount of power connected to the grid to zero. In step S347, the master M, which has received the requests in steps S345 and S346, sends a schedule change request to the slave S identified in the previous step that has power generation capacity or has a low priority. In step S348, slave S, which received the request in the previous step, sends a reply to master M. The slave S changes the supply and demand schedule as necessary, that is, when accepting the request. In the following step S349, each master M transmits the slave S's reply to the command device 2.

In step S350, the independent transfer unit 28 determines whether the balance of the DC bus 4 is zero based on the reply from the master M. If the independence transition unit 28 determines that the balance of the DC bus has been reduced to zero because some slaves S have responded to the change request, that is, that the power connected to the grid has been reduced to zero, the process proceeds to step S352, and if it is still within the range. If it is determined that the range is not within the range, the process advances to step S351. In step S351, the independence transition unit 28 identifies a slave S having a priority level one level higher than before, sends a request similar to that in step S346 to the master M to which the identified slave S is connected, and then sends a request similar to that in step S347 to the master M to which the identified slave S is connected. Return to That is, the independent transition unit 28 increases the priority level one step at a time until the DC bus capacity falls within the range and repeats the processing of steps S347 to S351. In step S352, the command device 2 saves the information of time t0+Δt and ends the process of FIG. 12.

According to the fourth embodiment described above, the following effects can be obtained.
(11) Processing priorities are set in the supply and demand schedule. The command device 2C includes an abnormality detection unit 27 that detects an abnormality in the power system, and when the abnormality detection unit 27 detects an abnormality, the command device 2C changes the supply and demand schedule with a low priority for the slave S to adjust the overall power balance of the slave S. An independent transition section 28 is provided which sets the power to zero and causes the main trunk 3 to disconnect from the power system. Therefore, the command device 2C can respond to abnormalities in the power system.

-Fifth embodiment-
A fifth embodiment of the microgrid system will be described with reference to FIGS. 13 and 14. In the following description, the same components as in the first embodiment are given the same reference numerals, and differences will be mainly explained. Points not particularly described are the same as the first embodiment. This embodiment differs from the first embodiment mainly in that it deals with power sales.

FIG. 13 is a diagram showing the configuration of a command device 2D in the fifth embodiment. In addition to the configuration of the first embodiment, the command device 2B further includes a maximum profit section 28A. The profit maximizing unit 28A performs scheduling to maximize the profit of the microgrid system 1D using surplus power. Note that maximizing profits also includes minimizing expenses.

In this embodiment, times t0, t1, and t2 are used for explanation as later times. That is, the time after time t0 is time t1, and the time after time t1 is time t2. The microgrid system 1D performs the process shown in FIG. 14 when the command device 2 detects that a surplus is predicted to occur in the electric power of the microgrid system 1D at future time t1.

In step S361, the maximum profit unit 28A of the command device 2 detects that it is predicted that a surplus will occur in the electric power of the microgrid system 1D at a future time t1. Note that the actual time at this time is time t0. In step S362, the command device 2 acquires the buying and selling price prediction data of the power exchange 91 from the current time t0 to the time t2. In the following step S363, the command device 2 sends to each master M a request to advance the demand schedule up to time t2. Further, in step S364, the command device 2 sends a request to each master M to consider incorporating charging the storage battery into the schedule.

In step S365, each master M sends a request to each slave S to bring forward the demand and charge the storage battery until time t2, corresponding to steps S363 and S364. Each slave S examines the request from the master M, and if possible, makes changes according to the request to change the supply and demand schedule. The slave S then replies to the master M whether the change is possible or not. In step S367, master M sends the response from slave S to command device 2.

In step S368, the command device 2 uses the response from the slave S received from the master M to bring forward the demand within the range up to time t2, and determines a schedule that maximizes the revenue from charging and electricity sales. For example, linear programming can be used to determine this schedule. In step S369, the command device 2 stores the schedule determined in step S368 in an information table, broadcasts it to each master M, and completes the process shown in FIG. EX5.

According to the fifth embodiment described above, the following effects can be obtained.
(12) When the command device 2D determines that the overall power balance of the slave S at a predetermined time is positive, the command device 2D determines the timing for consuming power in the slave S, the timing for charging by the slave S, and the timing for selling power. The profit maximum section 28A calculates a schedule that maximizes profit by operating at least one of the above, and controls the slave S and the manager 3 based on the calculated schedule. Therefore, the command device 2D can reduce the operating cost of the microgrid system 1D.

-Sixth embodiment-
A sixth embodiment of the microgrid system will be described. In the following description, the same components as in the first embodiment are given the same reference numerals, and differences will be mainly explained. Points not particularly described are the same as the first embodiment. The present embodiment differs from the first embodiment mainly in that processing for attaching and detaching the device wiring 6 is added.

In this embodiment, when the device wiring 6 is connected, the master M and slave S execute the following processes (1.1) to (1.10). (1.1) Contact of the communication line 6C of the device wiring 6 is established. (1.2) The slave signal processing unit 73 of the slave S performs a power-on reset operation. (1.3) The master M inquires of each slave S to which it is connected whether or not the information table and voltage/current table have been updated. (1.4) Each slave S responds to the inquiry as to whether there is an update. (1.5) Master M calculates the current voltage that can be assigned to each slave S. (1.6) Master M notifies each slave S of the current and voltage that can be assigned.

(1.7) Each slave S determines the received current and voltage specifications, and prepares to change the operation mode of the slave power converter 71 or the load 72. (1.8) Each slave S reports completion of preparation to master M. (1.9) The master M sets the operation of the power converter 51 connected to the receptacle 6RE or plug 6PU of each slave S and turns on the semiconductor switch 54. (1.10) Energization state is established. After this, the operation of confirming that the communication line C is connected is repeated periodically.

Each master M executes the following processes (2.1) to (2.5) when disconnecting from one connected slave S. (2.1) Master M detects a signal transmission failure in a certain slave S. (2.2) Turn off the semiconductor switch 54 for the slave. It is desirable that this process be performed within 25 ms after detecting the transmission failure. Next, the master M executes the process (2.3) or (2.4) depending on the power supply form of the slave S. (2.3) and (2.4) are for supplying power to enable the restart preparation operation for the slave S to make a positive connection.

When the slave S operates with power supplied from the power line, the following process (2.3) is performed. (2.3) The master M sets the slave power line to the minimum voltage standard value and turns on the semiconductor switch 54. Note that the minimum voltage specification value is 5V according to USB. When the slave S operates with power supplied from the communication line, the master M performs the following process (2.4). (2.4) Master M continues to supply a predetermined voltage to communication line 6C.

According to the sixth embodiment described above, the following effects can be obtained.
(13) The master M includes a signal processing unit 52 that starts supplying power to the slave device after establishing communication with the slave S and confirming the voltage and current of the slave S. Therefore, master M can safely supply power to slave S.

-Seventh embodiment-
A seventh embodiment of the microgrid system will be described with reference to FIGS. 15 and 16. In the following description, the same components as in the first embodiment are given the same reference numerals, and differences will be mainly explained. Points not particularly described are the same as the first embodiment. This embodiment differs from the first embodiment mainly in that AC power also flows inside the microgrid system.

FIG. 15 is a configuration diagram of a microgrid system 1F in the seventh embodiment. However, in FIG. 15, the description of the slave S and the description of the communication lines are omitted for convenience of drawing. The microgrid system 1F in this embodiment includes an AC bus 49 in addition to the configuration in the first embodiment. In other words, the main trunk 3 not only converts between alternating current and direct current, but also converts between alternating current and alternating current. The voltage of the AC bus 49 may be a constant voltage, for example, 200V or 100V, or may be changed depending on the situation like the DC bus 41.

The first master M1 to the m-th master Mm are connected to the DC bus 41, and the m-th master Mm to the x-th master Mx are connected to the AC bus 49. That is, the m-th master Mm is connected to both the DC bus 41 and the AC bus 49. The m-th master Mm is capable of supplying power to and acquiring power from both the DC bus 41 and the AC bus 49, and the ratio thereof can be set arbitrarily. The command device 2 determines the ratio of power that the m-th master Mm acquires from the DC bus 41 and the AC bus 49, or the ratio of power that the m-th master Mm outputs to the DC bus 41 and the AC bus 49, and Notify master Mm.

FIG. 16 is a configuration diagram of the m-th master Mm. The m-th master Mm includes a power conversion section 51, an ACDC signal processing section 52A, a communication section 53, a semiconductor switch 54, and a wattmeter 55. Furthermore, the m-th master Mm is connected to the ma-th slave Sma to the me-th slave Sme that use DC power, and the mf-th AC slave SmfAC to mj-th AC slave SmjAC that use AC power. The slave S using AC power is connected to the m-th master Mm by an AC power line 6AC and a communication line 6C. For example, ECHONET Lite (registered trademark) can be used for communication between the mfAC slave SmfAC and the like using the communication line 6C.

The power conversion section 51, the communication section 53, and the semiconductor switch 54 are the same as those in the first embodiment, so their description will be omitted. The AC power conversion unit 51A mutually converts the AC power flowing through the AC bus 49 and the DC power used by the ma-th slave Sma to the me-th slave Sme based on instructions from the ACDC signal processing unit 52A. The ACDC signal processing section 52A has a function of controlling the AC power conversion section 51A in addition to the processing of the ACDC signal processing section 52A in the first embodiment. The ACDC signal processing section 52A controls the power conversion section 51 and the AC power conversion section 51A based on the command from the command device 2. For example, the ACDC signal processing section 52A may operate only the power conversion section 51 and stop the AC power conversion section 51A, or vice versa.

The wattmeter 55 measures the amount of power used and the amount of power supplied by each connected slave S, and notifies the ACDC signal processing unit 52A of the amount of power used and the amount of power supplied. However, the wattmeter 55 is not an essential component of the m-th master Mm, and the m-th master Mm may not include the wattmeter 55.

According to the seventh embodiment described above, the following effects can be obtained.

(14) The microgrid system 1F includes an AC bus 49, which is a wiring through which AC power flows, and an n-th master device Mn to an x-th master device Mx that are connected to the main trunk 3 by the AC bus 49. The main trunk 3 further includes a power converter that converts alternating current power to each other.

(Modification of seventh embodiment)
In the seventh embodiment described above, the mfAC slave SmfAC and the like that operate using AC power are connected to the mth master Mm by the AC power line 6AC and the communication line 6C. However, the communication line 6C may be omitted and communication may be performed using the AC power line 6A. Known power line carrier communication can be used for this communication.

In each of the embodiments and modifications described above, the configuration of the functional blocks is merely an example. Several functional configurations shown as separate functional blocks may be integrated, or a configuration shown in one functional block diagram may be divided into two or more functions. Further, a configuration may be adopted in which some of the functions of each functional block are provided in other functional blocks.

In each of the embodiments and modifications described above, the program of the command device is stored in a ROM (not shown), but the program may be stored in the command device storage section. Further, the command device may be provided with an input/output interface (not shown), and the program may be read from another device when necessary via a medium that can be used by the input/output interface and the command device. Here, the medium refers to, for example, a storage medium that is removably attached to an input/output interface, or a communication medium, that is, a wired, wireless, or optical network, or a carrier wave or digital signal that propagates through the network. Further, part or all of the functions realized by the program may be realized by a hardware circuit or an FPGA.

Each of the embodiments and modifications described above may be combined. Although various embodiments and modifications have been described above, the present invention is not limited to these. Other embodiments considered within the technical spirit of the present invention are also included within the scope of the present invention.

1, 1A to 1F... Microgrid system 2, 2A to 2F... Command device 3... Master 4... DC bus 6... Equipment wiring 21... Master control section 22... Master control section 23... Command device communication section 24... Ratio setting section 25 ...Sub converter setting section 26...Change handling section 27...Abnormality detection section 28...Independent transition section 28A...Maximum profit section 29...Command device storage section 41...DC bus 43...Sub converter 49...AC bus 51...Power conversion section 51A...AC power conversion unit 52...Signal processing unit 52A...ACDC signal processing unit 71...Slave power conversion unit 291...Time series supply and demand table 292...Efficiency table 293...Master efficiency information

Claims (15)

A command device that controls a master trunk connected to a power system through which alternating current power flows and equipped with a power conversion device,
The main trunk is connected to one or more master devices by a DC bus, which is a wiring through which DC power flows,
The master device converts the power of the DC bus and supplies it to one or more slave devices via device wiring,
a master control unit that causes the master to control at least one of the current and voltage of the DC bus;
A command device comprising: a master control unit that causes the master device to control at least one of a current and a voltage of the device wiring. The command device according to claim 1,
The master control unit is a command device that causes the master to control at least one of the current and voltage of the DC bus based on the power demand and power supply of the slave device at the current time obtained from the slave device. The command device according to claim 1,
The master control unit instructs the master to control at least one of the current and voltage of the DC bus based on a supply and demand schedule that is a future demand and supply schedule for electric power of the slave device, which is acquired from the slave device. Device. The command device according to claim 1,
The DC bus includes a first DC bus and a second DC bus having different voltage levels,
A sub-converter including a transformer capable of changing DC voltage is connected to the first DC bus and the second DC bus,
At least one of the master devices is a dual-connection master device connected to the first DC bus and the second DC bus,
a ratio setting unit that specifies a ratio of power output or power input to the first DC bus and the second DC bus for the both connected master devices;
A command device further comprising: a sub-converter setting section that outputs a command regarding voltage change processing to the sub-converter. The command device according to claim 3,
Processing priorities are set in the supply and demand schedule,
The command device further includes a change handling unit that causes the slave device to change the supply and demand schedule having a low priority when the supply and demand schedule is changed. The command device according to claim 3,
Processing priorities are set in the supply and demand schedule,
an abnormality detection unit that detects an abnormality in the power system;
When the abnormality detection unit detects an abnormality, it causes the slave device to change the demand/supply schedule with the low priority to make the entire power balance of the slave device zero, and causes the master device to connect to the power system. The command device further includes an independent transition section for disconnecting. The command device according to claim 1,
When determining that the overall power balance of the slave device at a predetermined time is positive, at least one of the timing of consuming power in the slave device, the timing of charging by the slave device, and the timing of selling power is determined. A microgrid system further comprising: a revenue maximizing section that calculates a schedule that maximizes revenue by operating the system, and controls the slave device and the master based on the calculated schedule. The command device according to claim 1,
The master control unit controls the current of the DC bus so that power loss is minimized based on information on power conversion efficiency of power conversion devices included in the master, each of the master devices, and each of the slave devices. and a command device that controls at least one of voltage. In a microgrid system including a command device, a main trunk connected to a power system through which AC power flows, one or more master devices, and one or more slave devices,
The main trunk is connected to the one or more master devices by a DC bus, which is a wiring through which DC power flows,
The master device is connected to one or more of the slave devices by device wiring, which is a wiring through which DC power flows;
The command device is
a master control unit that causes the master to control at least one of the current and voltage of the DC bus;
a master control unit that causes the master device to control at least one of the current and voltage of the device wiring,
A microgrid system in which each of the master devices includes a power conversion unit that converts the voltage of DC power. The microgrid system according to claim 9,
The slave device transmits a demand and supply schedule, which is a schedule of future demand and supply regarding electric power of the slave device, to the command device via the master device, or transmits a supply and demand schedule to the command device without going through the master device. A microgrid system that directly transmits the supply and demand schedule. The microgrid system according to claim 9,
The master device is a microgrid system including a signal processing unit that starts supplying power to the slave device after establishing communication with the slave device and confirming voltage and current to the slave device. The microgrid system according to claim 9,
AC bus, which is the wiring through which alternating current power flows,
further comprising one or more AC master devices connected to the main trunk by the AC bus,
The main microgrid system further includes a power converter that converts alternating current power. The microgrid system according to claim 9,
The slave device includes a power generation slave device capable of generating power,
The power generation slave device is a microgrid system that can supply power to other slave devices. The microgrid system according to claim 9,
The slave device includes a power generation slave device capable of generating power,
The master device connected to the power generation slave device is capable of supplying power generated by the power generation slave device to the slave device connected to another master device. A command method executed by a command device that controls a main trunk connected to a power system through which AC power flows and includes a power conversion device,
The main trunk is connected to one or more master devices by a DC bus, which is a wiring through which DC power flows,
The master device converts the power of the DC bus and supplies it to one or more slave devices via device wiring,
causing the master to control at least one of the current and voltage of the DC bus;
A command method comprising causing the master device to control at least one of a current and a voltage of the device wiring.

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