JP7595444B2 - Power Management System - Google Patents

Description

The present invention relates to a power management system.

A conventional system has been disclosed that includes a solar cell device, a fuel cell device, a control unit, and a power management device. The control unit transmits information indicating the amount of power sold and the amount of power purchased to the power management device. Furthermore, the control unit transmits the amount of power sold originating from the solar cell and the amount of power sold originating from the fuel cell to the power management device.

JP 2011-101532 A

In recent years, VPPs (Virtual Power Plants), which use distributed power sources (e.g., solar cell devices, power storage devices, fuel cell devices, etc.) owned by facilities to stabilize the power grid, have been attracting attention. The reverse flow power output from the facility to the power grid is measured by a core power meter, such as a smart meter.

In this context, in an environment where two or more facilities are connected by a DC power grid (hereinafter, referred to as a microgrid), a case can be considered in which power output from a first facility is supplied to a second facility. In such a case, it is required to uniquely identify the power transmitted via the DC power grid, but the output power measured at the first facility does not necessarily match the power measured at the second facility.

The present invention has been made to solve the above-mentioned problems, and aims to provide a power management system that makes it possible to properly identify the power transmitted through the power grid.

The first feature of the disclosure is an energy management system having two or more facilities connected via a power grid, comprising: a receiver that receives, from a first facility included in the two or more facilities, a first information element indicating power output from the first facility to the power grid, and receives a second information element indicating power supplied from the power grid to a second facility included in the two or more facilities; and a controller that executes an adjustment process to adjust the power indicated by the first information element based on the power indicated by the second information element.

The present invention provides a power management system that can properly identify the power transmitted through the power grid.

FIG. 1 is a diagram showing a power management system 100 according to an embodiment. FIG. 2 is a diagram showing a facility 300 according to the embodiment. FIG. 3 is a diagram showing the management server 200 according to the embodiment. FIG. 4 is a diagram for explaining the adjustment process according to the embodiment. FIG. 5 is a diagram illustrating a power management method according to an embodiment. FIG. 6 is a diagram for explaining the correction process according to the first modification.

The following describes the embodiments with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic.

[Embodiment]
(Power Management System)
A power management system according to an embodiment will be described below.

As shown in FIG. 1, the power management system 100 includes a management server 200 and a facility 300. In FIG. 1, facilities 300A to 300D are shown as examples of the facility 300.

Each facility 300 is connected to a power grid 110. The power grid 110 includes at least a DC power grid 111. The power grid 110 may also include an AC power grid 112.

Hereinafter, the flow of power from the power grid 110 to the facility 300 is referred to as a forward flow, and the flow of power from the facility 300 to the power grid 110 is referred to as a reverse flow. Forward flow power may also be referred to as purchased power, and reverse flow power may also be referred to as sold power.

The management server 200 and the facility 300 are connected to a network 120. The network 120 may provide a line between the management server 200 and the facility 300. For example, the network 120 may include the Internet. The network 120 may include a dedicated line such as a VPN (Virtual Private Network).

The management server 200 is an example of a power management server that adjusts the supply and demand balance of the power system 110. The management server 200 is a server managed by a business operator such as a power generation business operator, a power transmission and distribution business operator, a retail business operator, or a resource aggregator. The resource aggregator may be a power business operator that provides reverse flow power to the power generation business operator, the power transmission and distribution business operator, the retail business operator, etc. in the VPP. The resource aggregator may be a power business operator that generates reduced power of the forward flow power (power consumption) of the facility 300 managed by the resource aggregator.

The management server 200 may transmit a control message to each facility 300 instructing control of the distributed power source (e.g., solar cell device 311, fuel cell device 321, or power storage device 331) owned by the facility 300. For example, the management server 200 may transmit a power flow control message requesting control of a power flow, or may transmit a reverse flow control message requesting control of a reverse flow. Furthermore, the management server 200 may transmit a power source control message to control the operating state of the distributed power source. The degree of control of the power flow or reverse flow may be expressed as an absolute value (e.g., XX kW) or a relative value (e.g., XX%). Alternatively, the degree of control of the power flow or reverse flow may be expressed in two or more levels. The degree of control of the forward or reverse flow may be represented by the electricity price (RTP; Rea Time Pricing) determined by the current electricity supply and demand balance, or by the electricity price (TOU; Time Of Use) determined by the past electricity supply and demand balance.

Facilities 300A to 300D are facilities that transmit or receive electricity via the DC power network 111. Facilities 300A to 300D may have the same configuration. However, the distributed power sources possessed by facilities 300A to 300D may be different. Below, a typical facility 300 is illustrated as an example.

As shown in FIG. 2, the system includes a solar cell device 311 (hereinafter, PV311), a DC/DC converter 312 (hereinafter, DC/DC312), a fuel cell device 321 (hereinafter, FC321), a DC/DC converter 322 (hereinafter, DC/DC322), a power storage device 331 (hereinafter, BT331), a DC/DC converter 332 (hereinafter, DC/DC332), an inverter 340 (hereinafter, INV340), a distribution board 350, an AC load 361, a DC load 362, an EV charger 363, a DC/DC converter 370 (hereinafter, DC/DC370), an SM381, and a measurement unit 382.

PV311 is a distributed power source that generates power in response to light such as sunlight. For example, PV311 includes a solar panel. In the example shown in FIG. 2, PV311 does not include a power conditioning system (PCS).

The DC/DC 312 converts the direct current power (hereinafter, DC power) output from the PV 311. For example, the DC/DC 312 boosts the DC power output from the PV 311.

FC321 is a distributed power source that generates power using fuel. For example, FC321 includes a fuel cell. In the example shown in FIG. 2, FC321 does not include a PCS. FC321 may be a solid oxide fuel cell (SOFC), a polymer electrolyte fuel cell (PEFC), a phosphoric acid fuel cell (PAFC), a molten carbonate fuel cell (MCFC), or the like.

DC/DC322 converts the DC power output from FC321. For example, DC/DC322 boosts the DC power output from FC321.

BT331 is a distributed power source that charges and discharges power. For example, BT331 includes a storage cell. In the example shown in FIG. 2, BT331 does not include a PCS.

DC/DC332 converts the DC power (discharge power) output from BT331. For example, DC/DC332 boosts the DC power output from BT331. DC/DC332 converts the DC power (charge power) output from INV340. For example, DC/DC332 lowers the DC power output from INV340.

INV340 converts the DC power output from each DC/DC converter (DC/DC312, DC/DC322, DC/DC332) into alternating current power (hereinafter, AC power). When BT331 is present, INV340 converts the AC power supplied from the AC power network 112 into DC power.

The distribution board 350 branches the power lines in the facility 300 that are connected to the AC power grid 112. In the example shown in FIG. 2, the distribution board 350 branches the power lines connected to the AC power grid 112 into a power line connected to the INV 340 and a power line connected to the AC load 361. The distribution board 350 may have a breaker for disconnecting the facility 300 from the AC power grid 112.

AC load 361 is a load that operates using AC power. Therefore, AC load 361 is connected to an AC power line. AC load 361 may include air conditioners, lighting equipment, AV (audio visual) equipment, etc.

The DC load 362 is a load that operates using DC power. Therefore, the DC load 362 is connected to a DC power line. The range connected by the DC power line may be referred to as a DC link. Although not limited thereto, the DC load 362 may include lighting equipment.

EV charger 363 is a device for charging an electric vehicle (hereinafter, EV). EV charger 363 is connected to a direct current power line. EV charger 363 may have a DC/DC converter. In an embodiment, when an EV is connected to EV charger 363, the EV may be treated in the same manner as BT 331, and EV charger 363 may be treated in the same manner as DC/DC 332.

DC/DC370 converts the DC power output from each DC/DC converter (DC/DC312, DC/DC322, DC/DC332). DC/DC370 may function as a rectifier circuit. However, DC/DC370 may be omitted.

The SM381 measures at least one of forward flow power and reverse flow power in the relationship between the facility 300 and the AC power grid 112. The SM381 may be referred to as a smart meter.

The measurement unit 382 measures at least one of forward flow power and reverse flow power in the relationship between the facility 300 and the DC power grid 111. The measurement unit 382 may be a measurement unit certified by a third-party organization. The measurement unit 382 may be referred to as a certified meter.

(Management Server)
The management server according to the embodiment will be described below. As shown in FIG.

The management unit 210 is composed of a storage medium such as a non-volatile memory and/or a HDD.

For example, the management unit 210 manages data related to the facility 300 managed by the management server 200. The facility 300 managed by the management server 200 may be a facility 300 that has a contract with the entity that manages the management server 200. For example, the data related to the facility 300 includes power (reverse flow power or power sold) output from the facility 300 (hereinafter, the first facility) to the DC power grid 111, and power (forward flow power or power purchased) supplied from the DC power grid 111 to the facility 300 (hereinafter, the second facility). The data related to the facility 300 includes power (reverse flow power or power sold) output from the facility 300 to the AC power grid 112, and power (forward flow power or power purchased) supplied from the AC power grid 112 to the facility 300.

The communication unit 220 is configured by a communication module. The communication module may be a wireless communication module conforming to standards such as IEEE802.11a/b/g/n, ZigBee, Wi-SUN, LTE, 5G, and 6G, or may be a wired communication module conforming to standards such as IEEE802.3 and RS485.

For example, the communication unit 220 constitutes a receiving unit that receives a first information element indicating the power (reverse flow power or sold power) output from the first facility to the DC power network 111 and receives a second information element indicating the power (forward flow power or purchased power) supplied from the DC power network 111 to the second facility. The communication unit 220 may receive an information element indicating the power (reverse flow power or sold power) output from the facility 300 to the AC power network 112, or may receive an information element indicating the power (forward flow power or purchased power) supplied from the AC power network 112 to the facility 300.

The communication unit 220 may receive the first information element from the measurement unit 382. If the facility 300 has an EMS (Energy Management System), the communication unit 220 may receive the first information element from the EMS. Similarly, the communication unit 220 may receive the second information element from the measurement unit 382. If the facility 300 has an EMS, the communication unit 220 may receive the second information element from the EMS. The communication unit 220 may receive an information element indicating forward flow power regarding the AC power network 112 from the SM381 or the EMS. Similarly, the communication unit 220 may receive an information element indicating reverse flow power regarding the AC power network 112 from the SM381 or the EMS.

The control unit 230 may include at least one processor. The at least one processor may be configured by a single integrated circuit, or may be configured by multiple circuits (integrated circuit(s) and/or discrete circuit(s) etc.) communicatively connected.

For example, the control unit 230 is configured as a control unit that executes an adjustment process to adjust the power indicated by the first information element based on the power indicated by the second information element. In other words, in the adjustment process, the control unit 230 adjusts the reverse flow power (power to be sold) based on the forward flow power (power to be purchased).

Specifically, when there are two or more first facilities as first facilities, in the adjustment process, the control unit 230 determines the power (individual reverse flow power) of each first facility based on the power indicated by the first information element, determines the total power (total forward flow power) of the second facility based on the power indicated by the second information element, and adjusts the power of each first facility by apportioning the total power of the second facility according to the ratio of the power of each first facility.

(Adjustment Processing)
The adjustment process according to the embodiment will be described below. In Fig. 4, "A" to "D" represent power related to facilities 300A to 300D. Here, a case is illustrated in which facilities 300A and 300B are first facilities that output DC power to the DC power network 111, and facilities 300C and 300D are second facilities to which DC power is supplied from the DC power network 111.

As shown in FIG. 4, the sum of the reverse flow power (measured) measured by the measuring units 382 of the facilities 300A and 300B may not match the sum of the forward flow power (measured) measured by the measuring units 382 of the facilities 300C and 300D. Possible causes of such a discrepancy include transmission losses in the DC power network 111.

In the embodiment, taking into consideration such a situation, the management server 200 executes an adjustment process to adjust the reverse flow power (measured) based on the forward flow power (measured). As described above, in the adjustment process, the power of each first facility is adjusted by apportioning the total power of the second facility according to the ratio of the power of each first facility.

In the case shown in FIG. 4, the reverse flow power of facility 300A is corrected according to the formula A' = (C + D) x A/(A + B). Similarly, the reverse flow power of facility 300B is corrected according to the formula B' = (C + D) x B/(A + B).

Here, the adjustment process may be performed for a predetermined period (e.g., 30 minutes). In other words, the adjustment process may be performed every predetermined period.

In such a case, the information element transmitted from each facility 300 to the management server 200 may be the total value of the forward flow power and reverse flow power generated during a specified period. For example, when the forward flow power and reverse flow power are measured by the facility 300 during a specified period, the facility 300 may transmit to the management server 200 an information element indicating the difference between the integrated value of the forward flow power and the integrated value of the reverse flow power.

Alternatively, the information elements transmitted from each facility 300 to the management server 200 may be individual values of forward flow power and reverse flow power occurring in a specified period. For example, when forward flow power and reverse flow power are measured by the facility 300 in a specified period, the facility 300 may transmit to the management server 200 an information element indicating an integrated value of the forward flow power and an information element indicating the difference between the integrated values of the reverse flow power separately. In such a case, the terms first facility and second facility described above may be interpreted as terms for conceptually distinguishing between reverse flow power and forward flow power. In other words, it should be noted that one facility may correspond to both the first facility and the second facility.

(Power Management Method)
The power management method according to the embodiment will be described below. Here, the sequence between the facility 300 and the management server 200 will be described. In Fig. 5, the process related to the DC power network 111 will be mainly described.

As shown in FIG. 5, in step S10, the facility 300 transmits an information element indicating the power measured by the measuring unit 382 to the management server 200. As described above, the first facility transmits a first information element to the management server 200, and the second facility transmits a second information element to the management server 200.

In step S11, the management server 200 executes an adjustment process to adjust the reverse flow power (measured) based on the forward flow power (measured). For example, in the adjustment process, the management server 200 adjusts the power of each first facility by apportioning the total power of the second facility according to the ratio of the power of each first facility.

In step S12, the management server 200 transmits the adjustment result to the facility 300. The management server 200 may transmit the adjustment result to the first facility without transmitting the adjustment result to the second facility. The adjustment result includes an information element indicating the reverse flow power after the adjustment process for the first facility.

(Action and Effects)
In the embodiment, the management server 200 executes an adjustment process for adjusting the reverse flow power (measurement) based on the forward flow power (measurement). With such a configuration, the standard for adjusting the discrepancy between the total of the reverse flow power (measurement) and the total of the forward flow power (measurement) becomes clear, so that the reverse flow power transmitted via the DC power network 111 can be appropriately identified. Furthermore, by using the forward flow power (measurement) as the standard rather than the reverse flow power (measurement), it is possible to prevent a situation in which the transmission loss in the DC power network 111 is inappropriately reflected.

[Modification 1]
Modification 1 of the embodiment will be described below. Differences from the embodiment will be mainly described below.

In the first modified example, a case will be considered in which a fee is paid for the reverse flow power output from the facility 300 to the DC power grid 111. The fee may be a monetary value, or an environmental added value certified by a third party. The environmental added value may be certified by a green power certificate.

In such a case, the management server 200 executes a correction process to correct the price for the electricity after the adjustment process (i.e., the sold power related to DC power) based on the sold and bought power of each of the two or more facilities 300. Sold and bought power is a general term for sold power (reverse flow power) and purchased power (forward flow power). The sold and bought power of each of the two or more facilities 300 may include sold and bought power related to DC power. The sold and bought power of each of the two or more facilities 300 may include sold and bought power related to AC power in addition to sold and bought power related to DC power.

For example, in the correction process, the management server 200 may correct the price for electricity after the adjustment process based on at least one of the difference and ratio of the purchased and sold electricity of two or more facilities.

(Correction process)
The correction process according to the first modification will be described below. Here, a case will be described in which the bought and sold power of both DC power and AC power is taken into consideration. Furthermore, a case will be illustrated in which the correction process is performed based on the difference between the bought and sold power.

As shown in FIG. 6, the difference in the power bought and sold at facility 300A is represented by the difference ("A" in FIG. 6) obtained by subtracting the power bought for AC power and DC power from the power sold for AC power and DC power. Similarly, the difference in the power bought and sold at facility 300B is represented by the difference ("B" in FIG. 6) obtained by subtracting the power bought for AC power and DC power from the power sold for AC power and DC power. The difference in the power bought and sold at facility 300C is represented by the difference ("C" in FIG. 6) obtained by subtracting the power bought for AC power and DC power from the power sold for AC power and DC power. Here, the difference "C" for facility 300C is the power purchased in excess of the power sold, and may be represented by a negative value. The difference in the power bought and sold at facility 300D is represented by the difference ("D" in FIG. 6) obtained by subtracting the power purchased for AC power and DC power from the power sold for AC power and DC power. In Figure 6, the relationship between the differences is A>D>B>C.

Under these assumptions, the management server 200 executes a correction process so that the facility 300 with the largest difference in purchased and sold power is favored. In other words, facility 300A is favored the most, and facility 300D is favored the least. For example, the management server 200 may identify a coefficient based on the difference in purchased and sold power, and multiply the price of sold power related to DC power by the coefficient. The possible range of the coefficient may be between 0.9 and 1.1.

In FIG. 6, a case has been described in which the correction process is performed based on the difference between the purchased and sold power. However, modified example 1 is not limited to this. As described above, the correction process may be performed based on the ratio of the purchased and sold power. The ratio of the purchased and sold power is represented by the sold power/purchased power. For example, referring to FIG. 6, the relationship between the ratios is D>A>B>C.

In such a case, the management server 200 executes a correction process so that the facility 300 with a large ratio of purchased and sold power is favored. In other words, the facility 300D is favored the most, and the facility 300D is favored the least. For example, the management server 200 may identify a coefficient based on the ratio of purchased and sold power, and multiply the price of sold power related to DC power by the coefficient. The possible range of the coefficient may be between 0.9 and 1.1.

In FIG. 6, a case has been described in which the bought and sold power for both DC power and AC power is taken into consideration. However, modified example 1 is not limited to this. Since the correction process is a process for correcting the price for the power after the adjustment process (the sold power for DC power), the bought and sold power for DC power may be taken into consideration without taking into consideration the bought and sold power for AC power.

[Other embodiments]
Although the present invention has been described by the above-mentioned embodiment, the description and drawings forming a part of this disclosure should not be understood as limiting the present invention. From this disclosure, various alternative embodiments, examples and operating techniques will become apparent to those skilled in the art.

In the above disclosure, the DC power network 111 is exemplified as the power network that outputs power from the facility 300 (and the power network that supplies power to the facility 300). However, the above disclosure is not limited to this. The power network that outputs power from the facility 300 (and the power network that supplies power to the facility 300) may be an AC power network. Such an AC power network may be a power network to which the facility 300 is connected without being connected to a baseline power source such as a thermal power plant. Such a power network may be referred to as a microgrid.

Although not specifically mentioned in the above disclosure, the management server 200 may have a function of managing the time synchronized with the facility 300. For example, the management server 200 may periodically receive an information element indicating the current time from a time server synchronized with the facility 300. Alternatively, the management server 200 may receive a first information element and a second information element from the facility 300 along with an information element indicating the time at the facility 300.

Although not specifically mentioned in the above disclosure, the first information element may include information elements indicating the breakdown of the power output from the facility 300 to the DC power grid 111, i.e., the power output from each distributed power source (PV311, FC321, BT332) to the DC power grid 111 individually. Similarly, the second information element may include information elements indicating the origin of the power supplied from the DC power grid 111 to the facility 300, i.e., the power of each distributed power source (PV311, FC321, BT332) individually. In such a case, the power supplied from the DC power grid 111 to the facility 300 may be associated with the power output from each distributed power source (PV311, FC321, BT332) to the DC power grid 111.

Although not specifically mentioned in the above disclosure, the management server 200 may execute a correction process to correct the price for the electricity after the adjustment process (i.e., the power sold for DC power) so that the price for the power sold for DC power is equal to the price for the power purchased for DC power.

Although not specifically mentioned in the above disclosure, the management server 200 may execute the above adjustment process for a predetermined period (e.g., 30 minutes) and execute the above correction process for a settlement period longer than the predetermined period (e.g., one month).

In the above disclosure, an example is given of a course in which the adjustment process and the correction process are executed by the management server 200. However, the above disclosure is not limited to this. At least one of the adjustment process and the correction process may be executed by the EMS of each facility 300.

Although not specifically mentioned in the above disclosure, power may be instantaneous power (kW) or the accumulated power consumption (kWh) over a certain period (e.g., 30 minutes).

100...Power management system, 110...Power system, 111...DC power network, 112...AC power network, 120...Network, 200...Management server, 210...Management unit, 220...Communication unit, 230...Control unit, 300...Facility, 311...PV, 312...DC/DC, 321...FC, 322...DC/DC, 331...BT, 332...DC/DC, 340...INV, 350...Distribution board, 361...AC load, 362...DC load, 363...EV charger, 370...DC/DC, 381...SM, 382...Measurement unit

Claims (6)

An electricity management system having two or more facilities connected via an electricity grid,
a receiving unit that receives, from a first facility included in the two or more facilities, a first information element indicating a measurement value of power output from the first facility to the power grid, and receives, from a second facility included in the two or more facilities, a second information element indicating a measurement value of power supplied from the power grid to the second facility;
a control unit that executes an adjustment process to adjust the measured value of power indicated by the first information element based on the measured value of power indicated by the second information element ;
When the two or more first facilities are present as the first facility, the control unit, in the adjustment process,
Identifying a power measurement value for each of the first facilities based on the power measurement value indicated by the first information element;
determining an overall power measurement for the second facility based on the power measurement indicated by the second information element;
a power management system that adjusts the measured value of power for each of the first facilities by apportioning the measured value of total power for the second facility according to a ratio of the measured value of power for each of the first facilities ; The power management system of claim 1, wherein the power network includes a direct current power network. The power management system according to claim 1 , wherein the control unit executes the adjustment process for a predetermined period. The power management system according to claim 1 , wherein the control unit executes a correction process to correct a price for the power after the adjustment process, based on the bought and sold power of each of the two or more facilities. The power management system according to claim 4 , wherein the control unit, in the correction process, corrects the price for the power after the adjustment process based on at least one of a difference and a ratio between the amounts of power bought and sold at the two or more facilities. The power management system according to claim 4 or 5 , wherein the bought and sold power of each of the two or more facilities includes bought and sold power related to AC power in addition to bought and sold power related to DC power.