JP2014187780A - Method of operating power network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To give an effective guide for planning an application of emergency power interchange performed at a power supply interruption of a trunk system, at an application of a power network.SOLUTION: A power network system comprises a plurality of power cells each having a power router for asynchronous connection with an external power system, and is configured by connecting the plurality of power cells with each other by a power transmission line. When power interchange at an interruption of a trunk power supply is planned, on the basis of information on an excessive power of each power cell and a connection relation between the power cells, a linear planning problem for maximizing a total sum of the excessive power after power interchange is resolved with respect to an aggregate of power cells with a negative excessive power before power interchange. Thereby, a direction and a magnitude of a power to be transmitted by each power transmission line at power interchange are calculated.

Description

  The present invention relates to a power network system configured by asynchronously connecting a plurality of power cells to each other, and more specifically to a method of operating this power network system.

  In constructing a power supply system, not only will the power transmission network be expanded more stably, but in the future it will become an important issue to make the system capable of introducing a large amount of natural energy. Therefore, a power network system called Digital Grid (registered trademark) has been proposed as a new power network (Patent Literature 1: Patent No. 4783453, Non-Patent Literature 1: Refer to the website of the Digital Grid Consortium, http: //www.digitalgrid). .Org / index.php / jp /). Digital Grid (registered trademark) is a power network system in which a power network is subdivided into small cells and these are interconnected asynchronously. Each power cell is a small house, a building, or a commercial facility, and a large one is a prefecture or a municipality. Each power cell may have a load therein, as well as a power generation facility and a power storage facility. Examples of power generation facilities include power generation facilities that use natural energy such as solar power generation, wind power generation, and geothermal power generation.

  The power cells are connected asynchronously in order to freely generate power within each power cell and to allow the power cells to smoothly pass power. (In other words, even if a plurality of power cells are connected to each other, the voltage, phase, and frequency of power used in each power cell are asynchronous with other power cells.) FIG. Ten examples are shown. In FIG. 25, the backbone system 11 transmits the backbone power from the large-scale power plant 12. A plurality of power cells 21-24 are arranged. Each power cell 21-24 has loads such as a house 31 and a building 32, power generation facilities 33 and 34, and a power storage facility 35. Examples of power generation facilities include a solar power generation panel 33 and a wind power generator 34. The power storage facility is a storage battery 34 or the like. In this specification, the power generation facility and the power storage facility may be collectively referred to as a distributed power source.

  Furthermore, each power cell 21-24 includes power routers 41-44 that serve as connection ports (connection ports) for connection to other power cells and the backbone system 11. The power routers 41-44 have a plurality of legs (LEGs). (For convenience of paper width, the reference numerals of the legs are omitted in FIG. 25. The white circles attached to the power routers 41-44 are to be interpreted as the connection terminals of each leg.) Here, It has a connection terminal and a power converter, and each leg is given an address. In addition, the power conversion by a leg means changing from alternating current to direct current or from direct current to alternating current, and changing the voltage, frequency, and phase of electric power.

  All the power routers 41-44 are connected to the management server 50 by the communication network 51, and all the power routers 41-44 are integrated and controlled by the management server 50. For example, the management server 50 instructs each power router 41-44 to transmit or receive power for each leg using the address assigned to each leg. Thereby, power interchange between power cells is performed via the power routers 41-44.

  By realizing power interchange between the power cells, for example, one power generation facility 33, 34 and one power storage facility 35 can be shared by a plurality of power cells. If surplus power can be interchanged between power cells, the power supply / demand balance can be stably maintained while greatly reducing the equipment cost.

Patent 4783453

Digital Grid Consortium website (http://www.digitalgrid.org/index.php/jp/)

  One of the advantages of having power interchange between power cells is to cope with power outages. Even when the main system goes down due to a power failure, it is expected that a large-scale power failure can be avoided by allowing excess power to be interchanged between power cells. When operating a power network, even if the main power system fails, the power in the power network must be used interchangeably and maximally effectively, for example, to reduce the number of power cells that will fall into a power outage as much as possible Is natural. However, it is not always possible to receive power interchange from the adjacent power cell in an emergency. Since it is not realistic in terms of cost to install power generation facilities and power storage facilities so that surplus power is generated in most power cells, the adjacent power cells do not always have surplus power. It is important to plan appropriately from which power cell to which power cell should be accommodated in the event of a power failure in the main system, but there are effective guidelines for making an operation plan for emergency power interchange so far. There wasn't.

  An object of the present invention is to provide an effective guideline for preparing an operation plan for emergency power accommodation to be performed at the time of a power failure of a main system in operating a power network.

The operation method of the power network system of the present invention includes:
An operation method of a power network system comprising a plurality of power cells having power routers for asynchronous connection to an external power system, wherein the plurality of power cells are connected to each other by a transmission line,
In seeking a power interchange plan when the main system fails,
Based on the surplus power information of each power cell and the connection relationship between the power cells,
For a set of power cells in which surplus power is negative before power accommodation, the first purpose is to maximize the total surplus power after power accommodation, and the direction and magnitude of power transmitted through the transmission line are obtained. It is characterized by that.

  Since an appropriate emergency power interchange operation plan can be obtained, the surplus power of the power network can be used to the maximum extent possible, and the situation where the power cell falls into a power outage can be avoided as much as possible.

The figure which shows schematic structure of an electric power router. The figure which shows the internal structure of an electric power router in detail. The figure which shows an example which connected the electric power router to the backbone system, load, and various distributed power supplies. The figure which shows the example of a possible combination in the connection of electric power routers. The figure which shows the example of a possible combination in the connection of electric power routers. The figure which shows the example of the combination prohibited in the connection of electric power routers. The figure which shows the example of the combination prohibited in the connection of electric power routers. The figure which shows the example of the combination prohibited in the connection of electric power routers. The figure which shows the example of the combination prohibited in the connection of electric power routers. The figure which shows the example of the possible combination in the connection of electric power routers, when AC through leg is taken into consideration. The figure which shows the example of the possible combination in the connection of electric power routers, when AC through leg is taken into consideration. The figure which shows the example of the possible combination in the connection of electric power routers, when AC through leg is taken into consideration. The figure which shows the example of the possible combination in the connection of electric power routers, when AC through leg is taken into consideration. The figure which shows the example of the possible combination in the connection of electric power routers, when AC through leg is taken into consideration. The figure which put together the pattern of the combination in the connection between electric power routers. An example in which four power routers are connected to each other will be given. The figure which shows an example of a mode that several electric power routers were bus-connected. The figure which shows an example of the connection form which the backbone system intervened between the power routers. The flowchart which shows the whole process sequence of 1st Embodiment. The figure which shows the example of the information table of an electric power network. The figure for showing the example of calculation. The figure for showing the example of calculation. The figure for showing the example of calculation. The figure which shows the example of a priority table as 2nd Embodiment. The flowchart which shows the procedure of a calculation process in 2nd Embodiment. The flowchart which shows the procedure of a calculation process in 2nd Embodiment. The figure which shows a weight table in 3rd Embodiment. The figure for demonstrating the selection problem of the operation mode of a leg. The figure for demonstrating the selection problem of the operation mode of a leg. The figure for demonstrating the selection problem of the operation mode of a leg. The flowchart which shows the procedure of a leg operation mode setting process. The figure for demonstrating the system outline | summary of an electric power network system.

(Description of power router and power network system)
The present invention is intended to allow power to be efficiently exchanged between power cells so that the power network system can be optimally operated. As a prerequisite for this, there is a power network system using a power router. However, since the power router and the power network system using the power router are not yet known techniques, first, the power network system using the power router and the power router will be described.

  FIG. 1 is a diagram showing a schematic configuration of the power router 100. FIG. 2 is a diagram showing the internal configuration of the power router 100 in some detail. The power router 100 generally includes a DC bus 101, a plurality of legs 110-160, and a control unit 190.

The power router 100 has a DC bus 101, and a plurality of legs 110-160 are connected to the DC bus 101 in parallel. The DC bus 101 is for flowing DC power, and is controlled so that the voltage of the DC bus 101 is kept at a predetermined level. (How the voltage of the DC bus 101 is kept constant will be described later.)
Although the power router 100 is connected to the outside via each leg 110-160, all the power exchanged with the outside is once converted into direct current and placed on the direct current bus 101. Thus, once through the direct current, the difference in frequency, voltage, and phase becomes irrelevant, and the power cells can be connected asynchronously. Here, it is assumed that the DC bus 101 is a parallel type having a smoothing capacitor 102 as shown in FIG. A voltage sensor 103 is connected to the DC bus 101, and the voltage value of the DC bus 101 detected by the voltage sensor 103 is sent to the control unit 190.

Next, the legs 110-160 will be described.
A plurality of legs 110-160 are provided in parallel to the DC bus.
In FIG. 1, six legs 110-160 are shown. The six legs 110-160 are referred to as a first leg 110, a second leg 120,..., A sixth leg 160, as shown in FIG. In FIG. 1, the first leg 110 is shown as leg 1 and the second leg 120 is shown as leg 2 for the sake of paper width. In FIG. 2, the third leg 130 and the fourth leg 140 are omitted.

While the first leg 110 to the fifth leg 150 have the same configuration, the sixth leg 160 is different from the first to fifth legs 110-150 in that it does not have a power converter. First, the configuration of the first leg 110 to the fifth leg 150 will be described.
Since the first leg 110 to the fifth leg 150 have the same configuration, the configuration of the first leg 110 will be described as a representative.
The first leg 110 includes a power conversion unit 111, a current sensor 112, a switch 113, a voltage sensor 114, and a connection terminal 115.
The power conversion unit 111 converts AC power into DC power, or converts DC power into AC power. Since DC power is flowing through the DC bus 101, the power converter 111 converts the DC power of the DC bus 101 into AC power having a predetermined frequency and voltage, and flows the AC power from the connection terminal 115 to the outside. Alternatively, the power conversion unit 111 converts AC power flowing from the connection terminal 115 into DC power and flows the DC power to the DC bus 101.

The power conversion unit 111 has a configuration of an inverter circuit, that is, an antiparallel circuit 111P composed of a thyristor 111T and a feedback diode 111D is connected in a three-phase bridge. (That is, six anti-parallel circuits 111P are provided for one inverter circuit.) Here, since a three-phase AC is used, a three-phase inverter circuit is used. Also good. A wire drawn from a node between the two antiparallel circuits 111P and connecting the node and the connection terminal will be referred to as a branch line BL.
(Because it is a three-phase AC, one leg has three branch lines BL.)

  The direction of power, the frequency of AC power, and the like are controlled by the control unit 190. That is, the switching of the thyristor 111T is controlled by the control unit 190. Operation control by the control unit 190 will be described later.

  A switch 113 is disposed between the power conversion unit 111 and the connection terminal 115. By opening / closing the switch 113, the branch line BL is opened / closed, that is, the outside and the DC bus line 101 are cut off or connected. The voltage of the branch line BL is detected by the voltage sensor 114, and the current value of the current flowing through the branch line BL is detected by the current sensor 112. The opening / closing operation of the switch 113 is controlled by the control unit 190, and the detection values by the voltage sensor 114 and the current sensor 112 are output to the control unit 190.

In the above description, the power conversion unit is an inverter circuit, and the connection partner of the leg uses alternating current. However, the connection partner of the leg may use direct current such as the storage battery 35 in some cases.
(For example, the third leg 130 in FIG. 1 is connected to the storage battery 35.)
The power conversion in this case is DC-DC conversion. Therefore, an inverter circuit and a converter circuit may be provided in parallel in the power conversion unit, and the inverter circuit and the converter circuit may be selectively used depending on whether the connection partner is AC or DC. Or you may make it provide a leg only for DC-DC conversion whose power conversion part is a DC-DC conversion part. Rather than providing an inverter circuit and a converter circuit in parallel in all the legs, it is more advantageous in terms of size and cost to use a power router that has both a leg dedicated to AC-DC conversion and a leg dedicated to DC-DC conversion. There are many points.

  The configuration of the first leg 110 to the fifth leg 150 is as described above.

Next, the sixth leg 160 will be described.
The sixth leg 160 does not have a power conversion unit, that is, the connection terminal 165 of the sixth leg 160 is not connected to the DC bus 101. The sixth leg 160 is connected to the branch line BL of the fifth leg 150. The internal wiring of the sixth leg 160 is also referred to as a branch line BL. The branch line BL of the sixth leg 160 is connected between the connection terminal 155 of the fifth leg 150 and the switch 153 with respect to the fifth leg 150.

The sixth leg 160 includes a switch 163, a voltage sensor 164, a current sensor 162, and a connection terminal 165.
The branch line BL of the sixth leg 160 is connected to the branch line BL of the fifth leg 150 via the switch 163. That is, the connection terminal 165 of the sixth leg 160 is connected to the connection terminal 155 of the fifth leg 150. There is only a switch 163 between the connection terminal 165 of the sixth leg 160 and the connection terminal 155 of the fifth leg 150, and the sixth leg 160 does not have a power converter, so the connection terminal of the sixth leg 160 Between 165 and the connection terminal 155 of the fifth leg 150, power is conducted without undergoing any conversion.
Therefore, a leg having no power converter like the sixth leg 160 may be referred to as an AC through leg.

  Current sensor 162 and voltage sensor 164 detect the current value and voltage value of branch line BL and output them to control unit 190. The opening / closing operation of the switch 163 is controlled by the control unit 190.

(Regal operation mode)
As described above, the first leg 110 to the fifth leg 150 have power converters 111-151, and the switching operation of the thyristor in the power converter is controlled by the control unit 190.
Here, the power router 100 is in a node of the power network 10 and has an important role of connecting the backbone system 11, the load 30, the distributed power source, the power cell, and the like. At this time, the connection terminals 115-165 of the legs 110-160 are respectively connected to the backbone system 11, the load 30, the distributed power source, and the power routers of other power cells. The present inventors have realized that the role of each leg 110-160 differs depending on the connection partner, and that the power router cannot be established unless each leg 110-160 performs an appropriate operation according to the role.
The inventors of the present invention have the same leg structure, but change the operation of the leg depending on the connection partner.
The manner of driving the leg is referred to as an operation mode. The present inventors prepared three types of leg operation modes, and switched the mode depending on the connection partner.
Leg operating modes include
Master mode,
Independent mode,
There are designated power transmission / reception modes.
Hereinafter, it demonstrates in order.

(Master mode)
The master mode is an operation mode when connected to a stable power supply source such as a system, and is an operation mode for maintaining the voltage of the DC bus 101.
FIG. 1 shows an example in which the connection terminal 115 of the first leg 110 is connected to the backbone system 11. In the case of FIG. 1, the first leg 110 is operated and controlled as a master mode, and plays a role of maintaining the voltage of the DC bus 101. When many other legs 120-150 are connected to the DC bus 101, power may flow from the legs 120-150 to the DC bus 101, or power may flow from the legs 120-150. . When the power flows out from the DC bus 101 and the voltage of the DC bus 101 drops from the rating, the leg 110 that is in the master mode compensates for the power shortage due to the outflow from the connection partner (here, the main system 11). Alternatively, when power flows into the DC bus 101 and the voltage of the DC bus 101 rises from the rating, the excess power due to the inflow is released to the connection partner (here, the backbone system 11). In this way, the leg 110 in the master mode maintains the voltage of the DC bus 101. Thus, in one power router, at least one leg must be operated in master mode. Otherwise, the voltage of the DC bus 101 will not be maintained constant.
Conversely, two or more legs may be operated in the master mode in one power router, but it is better to have one master mode leg in one power router.
Moreover, you may connect the leg used as master mode to the distributed power supply (a storage battery is also included) which mounts a self-excited inverter other than a basic system, for example.
However, a distributed power source equipped with a separately excited inverter cannot be connected to a leg that becomes a master mode.

  In the following description, a leg operated in the master mode may be referred to as a master leg.

The operation control of the master leg will be described.
When activating the master leg: First, the switch 113 is opened (cut off). In this state, the connection terminal 115 is connected to the connection partner. Here, the connection partner is the backbone system 11. The voltage of the connection destination system is measured by the voltage sensor 114, and the amplitude, frequency, and phase of the system voltage are obtained using a PLL (Phase-Locked-Loop) or the like.
Thereafter, the output of the power conversion unit 111 is adjusted so that the voltage of the obtained amplitude, frequency, and phase is output from the power conversion unit 111. That is, the on / off pattern of the thyristor 111T is determined. When this output becomes stable, the switch 113 is turned on to connect the power conversion unit 111 and the system 11. At this time, since the output of the power converter 111 and the voltage of the grid 11 are synchronized, no current flows.

The operation control when operating the master leg will be described.
The voltage of the DC bus 101 is measured by the voltage sensor 103. If the voltage of the DC bus 101 exceeds the predetermined rated bus voltage, the power converter 111 is controlled so that power is transmitted from the master leg 110 toward the grid. (At least one of the amplitude and phase of the voltage output from the power converter 111 is adjusted so that power is transmitted from the DC bus 101 to the system 11 via the master leg 110.) The rated voltage 101 is determined in advance by setting.

On the other hand, if the voltage of the DC bus 101 is lower than a predetermined rated bus voltage, the power converter 111 is controlled so that the master leg 110 can receive power from the system 11.
(At least one of the amplitude and phase of the voltage output from the power converter 111 is adjusted so that power is transmitted from the system 11 to the DC bus 101 via the master leg 110.)
It will be understood that the operation of such a master leg enables the voltage of the DC bus 101 to maintain a predetermined rating.

(Independent mode)
The self-supporting mode is an operation mode in which a voltage having an amplitude and frequency designated by the management server 50 is generated by itself and power is transmitted to and received from a connection partner. For example, the operation mode is for supplying power toward a power consuming device such as the load 30. Or it becomes an operation mode for receiving the electric power transmitted from the connection partner as it is. FIG. 1 shows an example in which the connection terminal 125 of the second leg 120 is connected to the load 30. The second leg 120 is controlled to operate in the self-supporting mode, and power is supplied to the load 30.
In addition, when connected to another power router, such as the fourth leg 140 or the fifth leg 150, the fourth leg 140 or the fifth leg is used as a mode for transmitting the power required by the other power router. In some cases, 150 is operated in a self-supporting mode. Alternatively, when connected to another power router like the fourth leg 140 or the fifth leg 150, the fourth leg 140 or the fifth leg is set as a mode for receiving the power transmitted from the other power router. In some cases, 150 is operated in a self-supporting mode. Although not shown in the figure, the second leg can be operated in the self-supporting mode even when the second leg is connected to the power generation facility instead of the load 30. However, in this case, a separately-excited inverter is mounted on the power generation facility. The operation mode when connecting power routers will be described later.

  A leg operated in the self-supporting mode is referred to as a self-supporting leg. There may be a plurality of independent legs in one power router.

The operation control of the independent leg will be described.
First, the switch 123 is opened (shut off). The connection terminal 125 is connected to the load 30. The management server 50 instructs the power router 100 on the amplitude and frequency of power (voltage) to be supplied to the load 30. Therefore, the control unit 190 causes the power (voltage) having the instructed amplitude and frequency to be output from the power conversion unit 121 toward the load 30. (That is, the on / off pattern of the thyristor 121T is determined.)
When this output becomes stable, the switch 123 is turned on to connect the power converter 121 and the load 30. After that, if power is consumed by the load 30, the corresponding power flows from the self-supporting leg 120 to the load 30.

(Designated power transmission / reception mode)
The designated power transmission / reception mode is an operation mode for exchanging the power determined by the designation. That is, there are a case where the designated power is transmitted to the connection partner and a case where the designated power is received from the connection partner.
In FIG. 1, the fourth leg 140 and the fifth leg 150 are connected to other power routers.
In such a case, a predetermined amount of power is interchanged from one to the other. Alternatively, the third leg 130 is connected to the storage battery 35.
In such a case, a predetermined amount of power is transmitted to the storage battery 35 and the storage battery 35 is charged. Further, a distributed power source (including a storage battery) equipped with a self-excited inverter and a designated power transmission / reception leg may be connected.
However, a distributed power source equipped with a separately-excited inverter cannot be connected to a designated power transmission / reception leg.

  A leg operated in the designated power transmission / reception mode is referred to as a designated power transmission / reception leg. In one power router, there may be a plurality of designated power transmission / reception legs.

  The operation control of the designated power transmission / reception leg will be described. Since the control at the time of starting is basically the same as that of the master leg, it is omitted.

The operation control when operating the designated power transmission / reception leg will be described.
(In the description, the reference numerals attached to the fifth leg 150 are used.)
The voltage of the connection partner system is measured by the voltage sensor 154, and the frequency and phase of the connection partner voltage are obtained using a PLL (Phase-Locked-Loop) or the like. Based on the active power value and reactive power value specified from the management server 50 and the frequency and phase of the voltage of the connection partner, the target value of the current input / output by the power converter 151 is obtained.
The current value of the current is measured by the current sensor 152.
The power converter 151 is adjusted so that a current corresponding to the difference between the target value and the current value is additionally output. (At least one of the amplitude and phase of the voltage output from the power converter 151 is adjusted so that desired power flows between the designated power transmission / reception leg and the connection partner.)

  From the above description, it will be understood that the first to fifth legs having the same configuration can play the role of three patterns depending on the manner of operation control.

(Connection restrictions)
Since the operation of the leg differs depending on the operation mode, a restriction naturally occurs between the selection of the connection partner and the selection of the operation mode. That is, the operation mode that can be selected is determined when the connection partner is determined, and conversely, the connection partner that can be selected is determined when the operation mode is determined. (If the connection partner changes, it is necessary to change the operation mode of the leg accordingly.) A possible connection combination pattern will be described.

In the following description, the notation in the figure is simplified as shown in FIG.
That is, the master leg is represented by M.
The self-supporting leg is represented by S.
The designated power transmission / reception leg is represented by D.
AC through leg is represented by AC.
Further, the legs may be distinguished by attaching a number such as “# 1” to the shoulders of the legs as necessary.
Further, in FIG. 3 and subsequent figures, systematic symbols are assigned for each drawing, but the same symbols are not necessarily assigned to the same elements across the drawings.
For example, the reference numeral 200 in FIG. 3 and the reference numeral 200 in FIG. 4A do not indicate exactly the same thing.

  The connection combinations shown in FIG. 3 are all possible connections. The first leg 210 is connected to the backbone system 11 as a master leg. This is as already explained. The second leg 220 is connected to the load 30 as a self-supporting leg. This is also as already explained. The third leg 230 and the fourth leg 240 are connected to the storage battery 35 as designated power transmission / reception legs. This is also as already explained.

The fifth leg 250 is an AC through leg.
The AC through leg 250 is connected to the designated power transmission / reception leg of the other power router 300, and the AC through leg 250 is connected to the storage battery 35 via the connection terminal 245 of the fourth leg 240. Since the AC through leg 250 does not have a power conversion unit, this connection relationship is equivalent to that the designated power transmission / reception leg of the other power router 300 is directly connected to the storage battery 35. It will be appreciated that such a connection is allowed.

The sixth leg 260 is connected to the backbone system 11 as a designated power transmission / reception leg.
It will be understood that such a connection is allowed if the predetermined power is received from the backbone system 11 via the sixth leg 260.
In addition, in relation to the fact that the first leg 210 is a master leg, the master leg 210 is necessary from the backbone system 11 if the power received by the sixth leg 260 is not sufficient to maintain the rating of the DC bus 201. Power will be received. On the contrary, when the power received by the sixth leg 260 exceeds the amount necessary for maintaining the rating of the DC bus 201, the master leg 210 releases excess power to the backbone system 11.

Next, a case where power routers are connected will be described.
Connecting power routers means connecting a leg of one power router and a leg of another power router. When the legs are connected, there are restrictions on the operation modes that can be combined.

The connection combinations shown in FIGS. 4A and 4B are all examples of possible combinations.
In FIG. 4A, the master leg 110 of the first power router 100 and the self-supporting leg 210 of the second power router 200 are connected. Although not described in detail, it is assumed that the master leg 220 of the second power router 200 is connected to the backbone system 11 and thereby the voltage of the DC bus 201 of the second power router 200 is maintained at a rating.

In FIG. 4A, when power is supplied from the first power router 100 to the load 30, the voltage of the DC bus 101 decreases.
The master leg 110 procures power from the connection partner so as to maintain the voltage of the DC bus 101. That is, the master leg 110 draws the insufficient power from the independent leg 210 of the second power router 200.
The independent leg 210 of the second power router 200 sends out the power required by the connection partner (here, the master leg 110).
In the DC bus 201 of the second power router 200, the voltage is reduced by the amount of power sent from the self-supporting leg 210, but this is compensated from the backbone system 11 by the master leg 220. In this manner, the first power router 100 allows the necessary power to be accommodated from the second power router 200.

  As described above, even if the master leg 110 of the first power router 100 and the self-supporting leg 210 of the second power router 200 are connected, the roles of the master leg 110 and the self-supporting leg 210 are matched. There is no inconvenience. Therefore, it can be seen that the master leg and the independent leg may be connected as shown in FIG. 4A.

  In FIG. 4B, the designated power transmission / reception leg 310 of the third power router 300 and the self-supporting leg 410 of the fourth power router 400 are connected. Although not described in detail, the master leg 320 of the third power router 300 and the master leg 420 of the fourth power router 400 are each connected to the backbone system 11, and thus the third power router 300 and the fourth power router 400 are connected to each other. Each DC bus 301, 401 is assumed to maintain a rated voltage.

Here, it is assumed that the designated power transmission / reception leg 310 of the third power router 300 is instructed to receive the designated power by an instruction from the management server 50. The designated power transmission / reception leg 310 draws the designated power from the self-supporting leg 410 of the fourth power router 400.
The self-supporting leg 410 of the fourth power router 400 transmits the power required by the connection partner (here, the designated power transmission / reception leg 310). On the DC bus 401 of the fourth power router 400, the voltage drops by the amount of power sent from the self-supporting leg 410, but this is compensated from the backbone system 11 by the master leg 420.

  As described above, even if the designated power transmission / reception leg 310 of the third power router 300 and the independent leg 410 of the fourth power router 400 are connected, the roles of the designated power transmission / reception leg 310 and the independent leg 410 are matched. There is no inconvenience in either operation. Therefore, it is understood that the designated power transmission / reception leg and the independent leg may be connected as shown in FIG. 4B.

  The case where the third power router 300 has the power exchanged from the fourth power router 400 has been described as an example, but conversely, the case where the power is exchanged from the third power router 300 toward the fourth power router 400. But it will be understood that there are no inconveniences as well.

  In this way, the designated power can be interchanged between the third power router 300 and the fourth power router 400.

  When the legs having the power conversion unit are directly connected, only the two patterns shown in FIGS. 4A and 4B are allowed. That is, only the case where the master leg and the independent leg are connected and the case where the designated power transmission / reception leg and the independent leg are connected are allowed.

Next, combinations that cannot be connected to each other are listed.
5A to 5D are patterns that should not be connected to each other.
As can be seen from FIGS. 5A, 5B, and 5C, legs in the same operation mode must not be connected to each other. For example, in the case of FIG. 5A, the master legs are connected to each other. As described above in the description of the driving operation, the master leg first performs a process of generating power synchronized with the voltage, frequency, and phase of the connection partner.
Here, if the connection partner is also a master leg, they try to synchronize with each other's voltage and frequency, but since the master leg does not establish voltage and frequency autonomously, such synchronization processing cannot succeed. . Therefore, the master legs cannot be connected to each other.
There are also the following reasons. The master leg must draw power from the connection partner to maintain the voltage on the DC bus.
(Alternatively, in order to maintain the voltage of the DC bus, excess power must be released to the connection partner.)
If the master legs are connected to each other, they cannot satisfy each other's request.
(If the master legs are connected to each other, the voltage of the DC bus cannot be maintained by both power routers. Then, a malfunction such as a power failure may occur in each power cell.)
Thus, since the roles of the master legs collide with each other (because they do not match), the master legs should not be connected to each other.

In FIG. 5B, the designated power transmission / reception legs are connected to each other, but it will be understood that this also does not hold.
Although it is the same as the master leg, as described above in the description of the driving operation, the designated power transmission / reception leg also first performs processing for generating power synchronized with the voltage, frequency, and phase of the connection partner.
Here, if the connection partner is also the designated power transmission / reception leg, they will try to synchronize with each other's voltage and frequency, but the specified power transmission / reception leg does not establish voltage and frequency autonomously. Processing cannot be successful. Therefore, the designated power transmission / reception legs cannot be connected to each other.
There are also the following reasons. Even if the designated transmission power to be transmitted by one designated power transmission / reception leg 510 and the designated reception power to be received by the other designated power transmission / reception leg 610 are matched, such designated power transmission / reception is performed. Do not connect the legs together.
For example, it is assumed that one designated power transmission / reception leg 510 adjusts the power conversion unit so as to transmit the designated transmission power.
(For example, the output voltage is set higher than the connection partner by a predetermined value.) On the other hand, the other designated power transmission / reception leg 610 adjusts the power conversion unit so as to receive the designated received power. (For example, the output voltage is set to be lower than the connection partner by a predetermined value.) At the same time, if such an adjustment operation is performed in both of the designated power transmission / reception legs 510 and 610, they will be out of control. It will be understood that

In FIG. 5C, the independent legs are connected to each other, but such a connection should not be made.
A self-supporting leg creates its own voltage and frequency.
If any of the voltage, frequency, and phase generated by the two independent legs are slightly separated while the independent legs are connected to each other, unintended power flows between the two independent legs.
It is impossible to keep the voltage, frequency, and phase produced by the two free standing legs perfectly matched, so the free standing legs cannot be connected together.

In FIG. 5D, the master leg and the designated power transmission / reception leg are connected.
It will be understood from the above explanation that this also does not hold.
Even if the master leg 510 attempts to transmit / receive power to the connection partner so as to maintain the voltage of the DC bus 501, the designated power transmission / reception leg 610 does not transmit / receive power according to the request of the master leg 510. Therefore, the master leg 510 cannot maintain the voltage of the DC bus 501.
Further, even if the designated power transmission / reception leg 610 attempts to send / receive the designated power to / from the connection partner (510), the master leg 510 does not transmit / receive power in response to a request from the designated power transmission / reception leg 610. Therefore, the designated power transmission / reception leg 610 cannot transmit / receive the designated power to / from the connection partner (here, the master leg 510).

Up to this point, the case where the legs having the power conversion units are connected to each other has been considered. However, when the AC through leg is taken into consideration, the patterns of FIGS. 6A to 6D are also possible.
The AC through leg is simply a bypass because it does not have a power converter. Therefore, as shown in FIG. 6A and FIG. 6B, the master leg 110 of the first power router 100 is connected to the backbone system 11 via the AC through leg 250 of the second power router 200. It is essentially the same as being directly connected.
Similarly, as shown in FIGS. 6C and 6D, the designated power transmission / reception leg 110 of the first power router 100 is connected to the backbone system 11 via the AC through leg 250 of the second power router 200. This is essentially the same as that the power receiving leg 110 is directly connected to the backbone system 11.

Nevertheless, it is convenient to have AC through.
For example, as shown in FIG. 7, the distance from the first power router 100 to the main system 11 is very long, and in order to connect the first power router 100 to the main system 11, it passes through several power routers 200 and 300. There are cases where it is necessary to do this.
If there is no AC through leg, as shown in FIG. 4A, it is necessary to go through one or more independent legs.
When going through a leg having a power conversion unit, it goes through conversion from AC power to DC power and from DC power to AC power.
Although power loss still occurs in power conversion even if it is only a few percent, it is inefficient to require multiple times of power conversion just to connect to the backbone system. Therefore, it is meaningful to provide an AC through leg without a power conversion unit in the power router.

What has been described so far is summarized in FIG.
FIG. 9 shows an example in which four power routers 100-400 are connected to each other. Since any connection relation has appeared in the above description, each connection destination will not be described in detail, but it will be understood that both are permissible connection relations.

Here, it supplements about the connection line which connects an electric power router and a connection other party.
If a connection line connecting the power routers is referred to as a power transmission line, the power transmission line may be a part of the backbone system or may be disconnected from the backbone system.
(In FIG. 9, a transmission line 71A is attached to a transmission line that is a part of the backbone system, and a transmission line 71B is attached to a transmission line cut off from the backbone system.) Power routers may be connected. By connecting two or more power routers via the backbone system in this way, it becomes possible to accommodate power between the plurality of power routers via the backbone system, and to compensate for excess or deficiency of the interchanged power in the backbone system. You can also. On the other hand, two or more power routers may be connected without going through the backbone system.
Further, if the connection line connecting the power router and the load (or distributed power source) is referred to as a distribution line 72, the distribution line 72 is disconnected from the backbone system 11. That is, the distribution line 72 that connects the power router and the load (or distributed power source) is not connected to the backbone system 11.

Further, as illustrated in FIG. 10, the power routers 100 to 400 may be connected in a bus connection.
The description of the operation mode of each leg is omitted, but it is a matter of course that the operation mode of each leg must be appropriately selected in consideration of the direction of power interchange and the connection constraints described so far.
In FIG. 10, it goes without saying that the backbone system 11 may be replaced with a distributed power source such as a storage battery or a power generation facility. That is, a plurality of power routers may be bus-connected to the distributed power source.

The example shown in FIG. 11 is an example of a connection form in which two power routers 100 and 200 are connected to the backbone system 11.
In FIG. 11, the backbone system 11 may be replaced with a distributed power source.

  As described so far, the power router connection partner includes a main system, a distributed power source including a storage battery and a power generation facility, and other power routers. It is called a power system.

  With the power router, a power network system in which power cells are asynchronously interconnected can be constructed. Then, by following the connection restrictions described in this embodiment, the legs can be connected so that their roles do not contradict each other. Thereby, the power network system can be expanded and the whole can be stably operated.

(Problem of the present invention)
Problems to be solved by the present invention are as follows.
Even if the main system goes down due to a power failure, we want to avoid falling into a large-scale power failure by sharing surplus power between power cells. Simply, if the main power system fails, it is sufficient to combine the power in the power network, but for example, a result of a small number of power cells collecting excessive power from surrounding power cells. , The situation where many other power cells fall into a power outage must be avoided. In other words, the first requirement is to optimally distribute the power in the power network and increase the number of power cells that can be relieved as much as possible.
In addition, we want to avoid the situation where power is transmitted unnecessarily for a long distance just because there is surplus power in a distant power cell. Although power loss should be reduced as much as possible at the time of a power outage, if long-distance transmission is performed unnecessarily, power transmission is lost due to power interchange.
In other words, if the number of power cells that can be relieved in the event of a power failure is the same, the overall amount of power transmission should be as small as possible. This is the second request.
It is necessary to make an emergency power interchange operation plan that satisfies the first and second requirements.

(First embodiment)
A first embodiment of the present invention will be described. FIG. 12 is a flowchart showing the overall processing procedure of this embodiment. Each process is demonstrated in order.

First, as the preparation process ST100, the information table of the power network system is updated.
An example of the information table of the power network is shown in FIG. The information table of the power network is a summary of information on the power cells and transmission lines already installed.
Regarding the power cell, an ID number is assigned to each power cell, and information such as demand power, supply power, surplus power, and location is collected for each power cell. Regarding the power transmission line, information such as a power transmission / reception end, a power transmission capacity, and a power transmission efficiency is collected.

  The demand power is power consumed by a load in the power cell, and is expressed in unit watts [W]. For example, when the contracted wattage is determined for each household, factory, or commercial building existing in the power cell, the total of these may be used as demand power. Or it is good also as electric power required at the minimum even at the time of a power failure (at the time of a main system down). For example, power that is absolutely required by a hospital, power that is necessary to maintain a lifeline, and the like are estimated and totaled, and this may be used as demand power.

  The supplied power is power that can be output from the distributed power source in the power cell, and is expressed in unit watts [W]. For example, a power generation facility and a power storage facility are provided in the power cell, and the total of their maximum outputs may be used as the supply power. In short, it is power that can be supplied by the distributed power source of the power cell even during a power failure (when the main system is down). In the case of a power generation facility that uses natural energy, for example, the maximum design output may be used, or the power that can be generated may be estimated from past performance.

Surplus power is power that becomes surplus in the power cell at the time of a power failure (when the main system is down). Typically, a value obtained by subtracting demand power from supply power may be used. When the surplus power is a positive value, it means that the power cell has surplus power even during a power failure (when the main system is down).
On the other hand, when the surplus power is a negative value, it means that the power cell has insufficient power during a power failure (when the main system is down).

  The power transmission / reception end as the information of the power transmission line is information of the cells connected to each other by the power transmission line. For example, the power transmission line 1 connects the cell 1 and the cell 2, and the power transmission line 2 is the cell K. The cells at both ends of the transmission line such as being connected to the cell N are recorded. The transmission capacity is the transmission capacity of the transmission line. The power transmission efficiency represents a ratio of power lost by power transmission through the transmission line. For example, when 5% of power is lost due to power transmission, the power transmission efficiency is 0.95. As the transmission distance increases, the transmission efficiency decreases. (In addition, transmission efficiency may change depending on the transmission voltage.)

  When the information table can be created in this way, the preparation process ST100 ends, and the calculation process ST200 is then executed. The main point of the calculation step ST200 is to solve the following linear programming problem.

First, there are the following two objective functions.
(First objective function)
When a set of power cells whose surplus power is negative before power accommodation is represented by GS, the sum of the surplus power of the power cells included in the GS is maximized (approached to 0) after power accommodation.

(Second objective function)
Minimize the power transmitted during power interchange.

  Of the first and second objective functions, the first objective function is given higher priority.

Next, there are the following five constraints.
(First constraint)
The power flowing into a certain power cell and the power flowing out from this power cell are balanced.

(Second constraint)
For power cells whose surplus power is 0 or more before power accommodation, the surplus power after power accommodation does not become less than 0.
This means that instead of relieving other power cells, their power cells will not fail.

(Third constraint)
For the power cell in which the surplus power is negative before the power interchange, the surplus power after the power interchange does not deteriorate.
For example, for a power cell in which the surplus power before power interchange is minus 100 (kW), a situation where the surplus power after power interchange becomes minus 150 kW is avoided.

(Fourth constraint)
For power cells in which the surplus power is negative before power accommodation, the surplus power after power accommodation does not become positive.
This means that no power cells receive more power than necessary.

(Fifth constraint condition)
The power flowing through each transmission line during power interchange is less than or equal to the transmission capacity of each transmission line.

  The above first and second objective functions and the first to fifth constraint conditions are respectively formulated as follows. First, assume that constants and variables are set as follows. We will use uppercase for constants and lowercase for variables.

(constant)
G: Set of all cells GE: Set of cells whose surplus power before power interchange is 0 or more.
GS: A set of cells whose surplus power before power interchange is less than zero.
PO (i): surplus power of power cell i before power interchange.
C (i, j): Transmission capacity of the transmission line from the power cell i to the power cell j.
L (i, j): Transmission loss of the transmission line from the power cell i to the power cell j. (For example, when a loss of 5% occurs due to power transmission, L = 0.95.)

(variable)
p (i): surplus power of power cell i after power accommodation.
e (i, j): Electric power transmitted from the power cell i toward the power cell j. (It is the power transmitted by the power cell i and not the power received by the power cell j. Note that there is a transmission loss and the two are different.)

  Then, the first and second objective functions and the first to fifth constraint conditions are as follows.

(First objective function)

(Second objective function)

(First constraint)

(Second constraint)

(Third and fourth constraints)

(Fifth constraint condition)

Here, the first and second objective functions are summarized as follows so that the linear programming problem can be solved.
(Objective function)

Here, α is an arbitrary value satisfying the following expression.

  Here, since C (i, j) is the maximum transmission capacity of the transmission line from the power cell i to the power cell j, α defined in this way is applied to the first objective function, so that the first The objective function is given higher priority.

When the objective function is solved under the constraint conditions, e (i, j) is obtained. That is, it is required as to how much power is transmitted from which power cell to which power cell as emergency power interchange at the time of power failure of the main system. Therefore, an operation plan for performing power transmission according to e (i, j) is stored as an operation plan at the time of emergency power accommodation (ST300).
As an example, the emergency power accommodation plan may be stored in a management server, for example. Then, when the main system has a power failure (ST400: YES), power is transmitted between the power cells according to the emergency power interchange plan (ST500).

(Modification)
In the above description, according to e (i, j), how much power is transmitted from which power cell to which power cell is stored as a run plan at the time of emergency power accommodation, and emergency power accommodation is performed according to this plan. Executed. This means that power interchange is performed in the direction and magnitude according to e (i, j) on the assumption that the value of the load is constant.
Here, since the power consumption due to the load fluctuates, there is also an idea that it is not necessary to fix the magnitude of the power to be transmitted. In this case, only the direction of power transmission may be stored as an operation plan, and the magnitude of transmitted power may be adjusted according to the actual load when executing emergency power interchange. Needless to say, from the sign of e (i, j) (plus or minus or 0), it can be understood from which power cell to which power cell power should be transmitted in the event of a power failure.

(Example of calculation)
An example of calculation will be described with reference to FIGS. First, it is assumed that the state before power interchange is shown in FIG. FIG. 15 is an example of an information table.
There are power cells 1 to 4 as power cells. That is, G = {1, 2, 3, 4}.
The power cell 1 and the power cell 2 have surplus power. That is, GE = {1, 2}.
On the other hand, the power cell 3 and the power cell 4 have a negative surplus power, that is, the power is insufficient when the main system fails. That is, GS = {3, 4}.
The value of the surplus power of each power cell is as shown in FIG.
The transmission line is between power cell 1 and power cell 2, between power cell 2 and power cell 3, between power cell 3 and power cell 4, and between power cell 1 and power cell 4. Wired. Each transmission capacity is as shown in FIG. Moreover, the power transmission efficiency of each of these power transmission lines is as shown in FIG.

  Under these settings, solving the objective function while taking into account the constraint conditions gives the following results.

First, e (i, j) is determined as follows with respect to the direction and magnitude of the interchanged power.
e (1,2) = 14.583333
e (2,1) = 0.0000
e (2,3) = 61.666667
e (3,2) = 0.0000
e (3, 4) = 0.000000
e (4,3) = 5.0000000
e (4,1) = 0.0000
e (1,4) = 50.000000

At the same time, as a result of performing power accommodation according to e (i, j), surplus power p (i) of each power cell after power accommodation is obtained as follows.
p (1) = 25.416667
p (2) = 0.0000
p (3) = 0.0000
p (4) = 0.0000

  As can be seen from the result (FIG. 16), it can be seen that all the power cells are rescued from the power failure. In particular, regarding the power cell 3 and the power cell 4, it was found that if there was no power interchange, a power outage occurred, but the surplus power was 0 due to the power interchange, so no power outage occurred.

In addition, it is necessary to transmit power from the power cell 1 having the largest surplus power to the power cell 3 having the shortest power, but what kind of power is transmitted by what route is efficient. It is an unexpectedly difficult problem.
For example, since the transmission efficiency of the transmission line connecting the power cell 1 and the power cell 2 is low, the power transmission efficiency is better when the power cell 1 → 4 → 3 is transmitted than when the power cell 1 → 2 → 3 is transmitted. . However, the transmission capacity of the transmission line connecting the power cell 1 and the power cell 2 is as small as 50. In this regard, by solving the objective function described above, an optimal emergency power accommodation operation plan can be established.

(Second Embodiment)
In the first embodiment, all power cells have the same status.
Here, there may be power cells that should be preferentially interchanged in the event of a power failure in the backbone system and preferentially rescued from the power failure.
For example, hospitals and factories that are greatly affected by power outages. Further, there may be a power cell that can receive a high-quality power providing service according to a difference in power rate. Therefore, in the second embodiment, when the main system has a power failure, emergency power interchange is preferentially performed to a specific power cell for which power is insufficient, thereby avoiding a power failure of the power cell. Think.

First, as shown in FIG. 17, the priority of the power cell is set. The number of priority power cells may not be one, and a plurality of power cells may be designated as priority power cells. However, the priority order R is determined as the power cell priority. In FIG. 17, R is a priority order. That is, R = 1 is set for the power cell with the highest priority. Hereinafter, similarly, the second (R = 2), the third (R = 3),... Are set. Considering the linear programming problem described in the first embodiment while taking into account the priorities set in this way.
The following should be considered in this case.
That is, since the total surplus power is finite, not all priority power cells can be saved from a power outage. Therefore, the power cells having higher priority are saved in order.

18 to 19 are flowcharts showing the procedure of the arithmetic processing.
First, in ST600, a constraint condition and an objective function are formulated. Basically, it is the same as the first embodiment.
However, power cells for which priority is set are considered as follows.
That is, it is determined whether or not the surplus power of the power cell for which priority is set is negative. If the surplus power of the power cell for which priority is set is negative, the surplus power of the power cell after power accommodation is fixed to 0 (handled as a constant). If the ID number of the power cell with priority R is represented by x (R), it means that p (x (R)) = 0 is set.
Also, this x (R) is removed from GS.
At this time, the power cell of R = 1 is considered in order, and R is incremented every time the flow loop returns.
Therefore, in the first process, only R = 1 power cells are taken into account.

Then, the calculation is executed (ST601).
In this case, when p (x (R)) = 0 is forcibly set as described above, there are cases where a solution is obtained and a solution cannot be obtained.

If a solution is obtained (ST602: YES), this solution (p (i), e (i, j)) is temporarily stored (ST603).
On the other hand, if no solution is obtained (ST602: NO), it cannot be relieved even though the power cell has a high priority. Therefore, the power cell x (R) is handled in the same manner as a normal (no priority) power cell. Specifically, p (x (R)) is returned to a variable (ST604), and x (R) is added to GS (ST605).

Subsequently, it is further determined whether there is a priority power cell (ST606).
For example, if the power cell with R = 1 is considered in ST600, it is next determined whether or not there is a power cell with the second priority (R = 2).
If there is a next priority power cell, it is determined whether or not the surplus power of the power cell is negative (ST607).
If the surplus power of this power cell is negative (ST607: YES), the power cell is considered to be rescued preferentially (ST608).
That is, the surplus power of the power cell after the power interchange is set to 0 (p (x (R) = 0)), and this x (R) is excluded from GS.

  As a matter of course, if the surplus power of the priority power cell is 0 or positive (ST607: NO), the linear programming problem of the first embodiment can be solved as it is without any special consideration, after the power interchange. The surplus power of the power cell does not become negative. Therefore, the priority power cell with a positive surplus power is skipped, and the next priority power cell is considered (ST606).

Then, the processing of ST608 is performed, and the process returns to the top of the flowchart (ST600).
Hereinafter, the processing of the flowchart is repeated in order of priority, and the solution (p (i), e (i, j)) stored when the processing of the power cell of the last priority is completed is the final solution ( ST606: NO, ST609).

  With the above processing, power cells can be relieved in order of priority.

(Third embodiment)
In the second embodiment, the priority is set as the order. Therefore, the algorithm of the flowchart is repeated according to the priority order so that power cells with higher priority can be relieved in order.
Here, since the priority can be set not as a ranking but as a relative weight, this will be briefly described as a third embodiment.

Information on “weight” is given to each power cell, and the possibility of power failure being avoided by emergency power interchange is controlled.
In FIG. 20, W is a weight. That is, the power cell ID number and the power cell weight W are associated with each other and stored in the table of FIG. Note that the value of the weight W is 1 or more, and the greater the value of the weight W, the higher priority is given to emergency power accommodation to the corresponding power cell.

Then, the weight set in this way is incorporated into the linear programming problem.
That is, the first objective function is changed as follows.

  The second embodiment is the same as the first embodiment except that the first objective function is changed.

  Of course, the second embodiment and the third embodiment may be combined.

As described above, according to the first to third embodiments, an appropriate emergency power interchange operation plan can be obtained, and the surplus power of the power network can be used as much as possible to avoid the situation where the power cell falls into a power outage as much as possible. .
Further, according to the above embodiment, the emergency power accommodation path can be selected so that the power transmission loss is as small as possible, so that the power can be used as effectively as possible, and as a result, the overall power generation cost can be suppressed.

The results of the first to third embodiments may be used for facility design.
For example, it is assumed that there is a power cell in which the surplus power after accommodation becomes minus 100 kW as a result of calculation. In this case, it can be seen that if the power generation capacity of the power cell is increased by 100 kW, the power cell will not fail.
In addition, when a new power cell is added to the existing power network, it is possible to obtain a solution to the problem of which existing power cell is most efficient to which the new power cell is connected.
Specifically, the linear programming problem described above is solved on the assumption that a new power cell is connected to one existing power cell.
This process may be repeated for all existing power cells to find an existing power cell that maximizes the number of power cells that can be relieved, and that existing power cell may be the connection destination of the new power cell.
In addition to the effective use of power, it is natural to consider the cost and power utilization efficiency in a well-balanced manner in addition to the cost such as the installation cost of the transmission line. For example, if the number of power cells that can be relieved is the same, it is natural to select the one with the lower installation cost.

(Leg operation mode selection)
When connecting power routers, it is not just a matter of wiring being connected, but connections must be made in accordance with restrictions so that normal operation is possible.
Specifically, an operation mode is set for each leg of the power router, and the operation of the leg differs depending on the operation mode. When connecting power routers, you must consider the combination of leg operating modes.
Regarding the connection restrictions between the operation modes of the legs, as described above, the power routers must be connected so that smooth power interchange can be realized between the power routers when the backbone system goes down.
The inventors have realized that when connecting power cells, it is necessary to set the operation mode of each leg in advance in consideration of a response during a power failure. Otherwise, even if the wiring itself is connected, normal operation cannot be performed, so power interchange cannot be performed, and eventually the power system cannot be maintained.

This problem will be explained in a little more detail.
Please see FIG.
In FIG. 21, there are a first power cell 1, a second power cell 2, and a third power cell 3.
The first power cell 1 includes a first power router 100, a load 30, and a storage battery 35.
The second power cell 2 has a second power router 200 and a load 30. The third power cell 3 includes a third power router 300 and a load 30.

Master legs 110, 210, and 310 of the first power router 100, the second power router 200, and the third power router 300 are connected to the backbone system 11, respectively.
In addition, an independent leg 120 of the first power router 100 and a designated power transmission / reception leg 220 of the second power router 200 are connected.
The designated power transmission / reception leg 150 of the first power router 100 is connected to the storage battery 35.
The independent legs 130, 230, and 320 of the first power router 100, the second power router 200, and the third power router 300 are connected to the load 30, respectively.
Here, when connecting the first power router 100 and the third power router 300, it is assumed that the designated power transmission / reception leg 140 of the first power router 100 and the independent leg 330 of the third power router 300 are connected. As described above, this connection relationship is an allowable combination.

  Now, it is assumed that the basic system 11 has gone down (see FIG. 22). Even if the main system 11 goes down, it is desired that the power of the storage battery 35 of the first power cell 1 can be maintained as the whole power system by accommodating the second power cell 2 and the third power cell 3. Therefore, when down of the main system 11 is detected, the following operation switching is performed. (The switched state is shown in FIG. 22.)

(It should be noted that various aspects may be considered as to how to detect the down of the main system 11 and how to instruct each power router to switch operation.
For each power router, the amount of power supplied from the master leg connection partner (here, the backbone system) can be monitored, and when the master leg connection partner goes down, a predetermined procedure is used for each leg. The operation mode may be switched. Alternatively, when the main system 11 is down, an instruction to switch the operation mode of the legs may be issued from the management server to each power router. )

First, paying attention to the first power router 100, the fifth leg 150 is connected to the storage battery 35, and its operation mode is the designated power transmission / reception mode.
The first power router 100 switches the operation mode of the fifth leg 150 from the specified power transmission / reception mode to the master mode because it wants to maintain the voltage of the DC bus using the power of the storage battery 35.
In the second power router 200, since the power is desired to be interchanged from the first power router 100, the operation mode of the second leg 220 is switched from the designated power transmission / reception mode to the master mode.
In the third power router 300, the operation mode of the third leg 330 is switched from the self-sustained mode to the master mode in order to obtain power from the first power router 100.
In short, the leg connected to the opponent with surplus power is made the master leg.

However, even if the operation mode of each leg is switched in this way, power interchange cannot always be performed normally.
In the relationship between the first power router 100 and the second power router 200, it is certain that normal power interchange can be performed from the first power router 100 to the second power router 200.
The other party to which the second leg 220 of the second power router 200 is connected is the second leg 120 of the first power router 100, and the second leg 120 of the first power router 100 is operated in the self-supporting mode. Accordingly, the second leg 120 of the first power router 100 can transmit power as much as the second leg 220 of the second power router 200 requires.

On the other hand, normal power interchange cannot be performed between the first power router 100 and the third power router 300 as it is.
The third leg 330 of the third power router 300 is the master leg, and the connection partner of the master leg 330 is the fourth router 140 of the first power router 100, and the fourth router 140 of the first power router 100 is It is a designated power transmission / reception leg.
This connection is an unacceptable combination as described above. Therefore, even if the third power router 300 tries to continue the operation with the power interchange from the first power router 100, the power interchange from the first power router 100 cannot be received as it is.

In addition, in the state of FIG. 22, there may also be a concept of switching the operation mode of the fourth leg 140 of the first power router from the designated power transmission / reception mode to the self-sustaining mode.
However, switching the operation mode of the legs in both the first power router and the third power router is not desirable as a countermeasure against a power failure.
The operation mode of the fourth leg 140 of the first power router 100 is switched from the designated power transmission / reception mode to the autonomous mode, and the operation mode of the third leg 330 of the third power router 300 is switched from the autonomous mode to the master mode. This is because the work takes time and there is a high possibility that it will not be possible to respond quickly to power outages.

  Therefore, if the countermeasure at the time of power failure is considered, as shown in FIG. 23, the first power router 100 is connected to the fourth leg 140 of the first power router 100 and the third leg 330 of the third power router. The fourth leg 140 must be a self-supporting leg.

  As described so far, the power routers must be connected so that smooth power interchange is realized between the power routers when the main system goes down. That is, the operation mode of the leg must also be fully considered.

A flowchart showing the procedure of the leg operation mode setting step is shown in FIG.
Through the processing of the first to third embodiments, which power cell is transmitted to which power cell is determined for emergency power accommodation. It is determined whether or not each of the transmission lines connecting the power cells is transmitted during emergency power interchange (ST710). When power interchange is not performed at the time of power failure of the main system (ST710: NO), the operation mode of each leg is set according to the first leg operation setting rule (ST720).

The first leg operation setting rule is the following leg operation rule.
It is assumed that the power cell X and the power cell Y are connected.
(That is, the power router XR of the power cell X and the power router YR of the power cell Y are connected. More specifically, the leg XRL of the power router XR and the leg YRL of the power router YR are connected. And are connected.)
Then, when the backbone system is not down, it is assumed that power is exchanged from the power cell X to the power cell Y.
At this time, the operation mode of the leg XRL of the power router XR and the leg YRL of the power router YR is set as follows.
“When the main system is not down, the operation mode of the leg XRL of the power router XR is set as the designated power transmission / reception mode, and the operation mode of the leg YRL of the power router YR is set as the self-supporting mode.
Then, when the main system goes down and a power failure occurs, the operation of the leg XRL of the power router XR and the leg YRL of the power router YR is stopped.
However, in the power router XR and the power router YR, if there is a leg connected to the distributed power source, the operation mode of the leg connected to the distributed power source is changed to the master mode when a power failure occurs in the backbone system. "

In short, the power transmission side is the designated power transmission / reception mode, and the power reception side is the self-sustaining mode.
In addition, since power is not interchanged during a power failure in the main system, the operation of the leg is stopped during a power outage in the main system.

In the first leg operation setting rule, the power transmission side is set to the designated power transmission / reception mode and the power reception side is set to the self-sustaining mode because this is more efficient in power transmission.
Operation is possible even when the power transmission side is set to the self-sustained mode and the power reception side is set to the designated power transmission / reception mode, and such setting of the operation mode is not excluded from the present invention.

On the other hand, when power interchange is performed at the time of power failure of the main system (ST710: YES), the operation mode of each leg is set according to the second leg operation setting rule (ST730).
The second leg operation setting rule is the following leg operation rule.
It is assumed that the power cell J and the power cell K are connected.
(That is, the power router JR of the power cell J and the power router KR of the power cell K are connected.
More specifically, the leg JRL of the power router JR and the leg KRL of the power router KR are connected. )
Then, when the main system fails, it is assumed that power is exchanged from the power cell J to the power cell K.
At this time, the operation modes of the leg JRL of the power router JR and the leg KRL of the power router KR are set as follows.
“The operation mode of the leg JRL of the power router JR is set to the self-supporting mode.
The operation mode of the leg KRL of the power router KR is set to the designated power transmission / reception mode when the main system is not out of power.
When the main system fails, the operation mode of the leg KRL of the power router KR is changed from the designated power transmission / reception mode to the master mode.
(Even when the main system fails, the operation mode of the leg JRL of the power router JR may remain in the self-sustaining mode.
In the power router JR, if there is a leg connected to the distributed power supply, the operation mode of the leg connected to the distributed power supply is set to the master mode in the event of a power failure in the main system. ) "

If the operation mode of each leg is set according to the second leg operation setting rule, it is possible to quickly cope with a power failure.
That is, even if the main system goes down, only the operation mode of the leg KRL needs to be changed from the designated power transmission / reception mode to the master mode only at the power router (power router KR) on the power receiving side.
(It is not necessary to change the operation mode of the leg on the power transmission side.)
Therefore, even if the power cell K does not have surplus power, when the main power system fails, the power cell K can maintain the voltage of the DC bus of the power router K at the rated power with the power received from the power cell J. It will be possible to avoid the situation of falling into.

With the above processing, even if the backbone system goes down, power interchange between the power cells can be executed appropriately, and a situation where a large-scale power outage occurs in the entire power network or in a wide area can be avoided. It becomes like this.
In addition, since power interchange is possible between power cells in the event of a power failure, excessive capital investment such as providing distributed power supply facilities such as storage batteries and power generation facilities in all power cells is not necessary.
Then, by appropriately setting the operation mode of the leg, it becomes possible to quickly cope with a power failure and to avoid the situation where the power cell falls into a power failure as much as possible.

The function to create and store the information table of the power network is considered to be most efficient in terms of system design to be provided in the management server 50. A table may be created and stored.
Each process of the processing flow described above may be calculated and judged according to a manual determined by a person (operator). Of course, an operation program of the power network system is previously set up and described above. Each process may be automatically executed by a computer.
The operation program of the power network system may be distributed in a state of being recorded on a computer-readable non-volatile recording medium, or may be downloaded to the computer in a wired or wireless manner and installed in the computer.

The storage battery may be read as a distributed power source including power generation equipment.
In the above description, all the power cells are connected to the main system, and the power cell normally receives power from the main system. And the state where the main system went down was called a power outage.
It is also possible that multiple power cells receive power from a (large) distributed power source even during normal times, rather than receiving power from the main grid during normal times. This means that the (large) distributed power source is down.

DESCRIPTION OF SYMBOLS 10 ... Electric power network system, 11 ... Core system, 12 ... Large-scale power plant, 21 ... Power cell, 30 ... Load, 31 ... House, 32 ... Building, 33 ... Solar power generation panel, 34 ... Wind generator, 35 ... Power storage facility (storage battery), 41 ... Power router, 50 ... Management server, 51 ... Communication network, 100. ..Power router, 101 ... DC bus, 102 ... smoothing capacitor, 103 ... voltage sensor, 110 ... leg, 111 ... power converter, 111D ... feedback diode, 111P Anti-parallel circuit, 111T: thyristor, 112 ... current sensor, 113 ... switch, 114 ... voltage sensor, 115 ... connection terminal.

Claims (12)

An operation method of a power network system comprising a plurality of power cells having power routers for asynchronous connection to an external power system, wherein the plurality of power cells are connected to each other by a transmission line,
In seeking a power interchange plan when the main system fails,
Based on the surplus power information of each power cell and the connection relationship between the power cells,
For a set of power cells in which surplus power is negative before power accommodation, the first purpose is to maximize the total surplus power after power accommodation, and the direction and magnitude of power transmitted through the transmission line are obtained. A method of operating a power network characterized by the above. The operation method of the power network according to claim 1,
Furthermore, the second object is to minimize the total power transmitted through the transmission line during power interchange. A method for operating an electric power network. In the operation method of the power network according to claim 1 or claim 2,
A power network operating method characterized in that, for a power cell whose surplus power is 0 or more before power interchange, the surplus power does not become negative after power interchange. In the operation method of the electric power network according to any one of claims 1 to 3,
A power network operating method, characterized in that, for power cells whose surplus power is negative before power accommodation, a constraint is that the surplus power does not decrease further after power accommodation. In the operation method of the electric power network according to any one of claims 1 to 4,
A method of operating an electric power network, characterized in that, for power cells whose surplus power is negative before power interchange, the constraint is that the surplus power does not turn positive after power interchange. In the operation method of the electric power network according to any one of claims 1 to 5,
Set the power cell that should be saved as a priority power cell by performing power interchange preferentially when the main system fails.
A method for operating a power network, characterized in that the power accommodation plan is obtained by fixing surplus power after power accommodation of the priority power cell to zero. In the operation method of the electric power network according to any one of claims 1 to 6,
Set a relative weight for each power cell according to the priority that should be remedied from the power outage at the time of power outage of the main system,
The first object is established as follows. A method for operating an electric power network.

here,
GS is a set of power cells whose surplus power is negative before power interchange,
i is the identification number of the power cell,
p (i) is the surplus power of the power cell i after power interchange,
W (i) is the weight of power cell i,
It is. In the operation method of the electric power network according to any one of claims 1 to 7,
The power router
A DC bus that maintains the voltage at a predetermined rating;
One connection end is connected to the DC bus, the other connection end is connected to an external connection partner as an external connection terminal, and power is bidirectionally converted between the one connection end and the other connection end. A power conversion leg having a function to
The power conversion leg is
When the voltage of the DC bus drops from the rating, the shortage of power is compensated from the connection partner, and when the voltage of the DC bus rises from the rating, the master mode sends the excess power to the connection partner,
A designated power transmission / reception mode in which the designated power is transmitted to the connection partner or the designated power is received from the connection partner; and
A self-sustained mode that creates voltage of specified amplitude and frequency by itself and transmits and receives power to and from the connection partner,
The operation is controlled in one of the operation modes of
The first power conversion leg of the first power router and the second power conversion leg of the second power router are connected, and the first power router and the second power router cannot receive power supply from the backbone system. Sometimes when power is accommodated by transmitting power from the first power conversion leg of the first power router to the second power conversion leg of the second power router,
When there is power supply from the backbone system,
The operation mode of the first power conversion leg of the first power router is the self-supporting mode,
The operation mode of the second power conversion leg of the second power router is the designated power transmission / reception mode,
When power supply from the backbone system is not received,
The operation mode of the first power conversion leg of the first power router is the self-supporting mode,
The operation mode of the second power conversion leg of the second power router is the master mode. The operation method of the power network system according to claim 8,
In the first power router, when the power supply from the backbone system cannot be received, the operation mode of the power conversion leg connected to the distributed power source is set to the master mode. Operation method. In the operation method of the electric power network according to any one of claims 1 to 7,
The power router
A DC bus that maintains the voltage at a predetermined rating;
One connection end is connected to the DC bus, the other connection end is connected to an external connection partner as an external connection terminal, and power is bidirectionally converted between the one connection end and the other connection end. A power conversion leg having a function to
The power conversion leg is
When the voltage of the DC bus drops from the rating, the shortage of power is compensated from the connection partner, and when the voltage of the DC bus rises from the rating, the master mode sends the excess power to the connection partner,
A designated power transmission / reception mode in which the designated power is transmitted to the connection partner or the designated power is received from the connection partner; and
A self-sustained mode that creates voltage of specified amplitude and frequency by itself and transmits and receives power to and from the connection partner,
The operation is controlled in one of the operation modes of
The third power conversion leg of the third power router and the fourth power conversion leg of the fourth power router are connected,
When the third power router and the fourth power router can receive power supply from the backbone system, the third power conversion leg of the third power router changes to the fourth power conversion leg of the fourth power router. When power is transmitted and the third power router and the fourth power router cannot receive power supply from the backbone system, the third power conversion leg of the third power router is used to transmit the power of the fourth power router. When not transmitting power to the fourth power conversion leg,
When there is power supply from the backbone system,
The operation mode of the third power conversion leg of the third power router is the designated power transmission / reception mode,
The operation mode of the fourth power conversion leg of the fourth power router is the independent mode,
When power supply from the backbone system is not received,
The operation of the third power conversion leg of the third power router and the fourth power conversion leg of the fourth power router are stopped. The operation method of the power network system according to claim 10,
When the third power router and the fourth power router cannot receive power supply from the backbone system, the operation mode of the power conversion leg connected to the distributed power source is set to the master mode. Operation method of the power network system. An operation program for a power network system comprising a plurality of power cells having power routers for asynchronous connection to an external power system, wherein the plurality of power cells are connected to each other by a transmission line,
In seeking a power interchange plan when the main system fails,
On the computer,
With the input of surplus power information of each power cell and the connection relationship between the power cells,
For a set of power cells in which surplus power is negative before power accommodation, the first purpose is to maximize the total surplus power after power accommodation, and the direction and magnitude of power transmitted through the transmission line is obtained. A power network system operation program characterized by

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