Microgrid

Abstract

To provide a technique capable of improving a renewable energy ratio and stabilizing power supply.SOLUTION: A microgrid 1 according to an aspect of the present disclosure includes a first power generation facility 2 that generates first power by using a non-storable first renewable resource, a storage facility 6 that stores a storable second renewable resource, and a second power generation facility that generates second power by using the second renewable resource.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to microgrids. [Background technology]

[0002] Microgrids are known that generate electricity using renewable resources. For example, when generating electricity using solar or wind power, output can become unstable depending on the amount of sunlight or wind power. Microgrids incorporate large-capacity storage batteries to stabilize the supply of electricity to consumers. Storage batteries can adjust the timing of power generation and supply by storing power. Technologies described in Patent Documents 1 and 2 are known as other methods for ensuring a stable supply of power.

[0003] Patent Document 1 discloses a technology for meeting power demand by supplying power between multiple microgrids that generate power using renewable energy. The technology described in Patent Document 1 improves the target utilization rate of renewable energy in one microgrid by having one microgrid purchase power from another microgrid.

[0004] Patent Document 2 discloses a technology for improving the stability of power supply by connecting multiple commercial power sources to a microgrid network. The technology described in Patent Document 2 prioritizes the multiple commercial power sources in consideration of costs. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-193861 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-223651 Summary of the Invention [Problem to be solved by the invention]

[0006] Introducing a large-capacity storage battery increases the equipment cost, and the storage battery also generates power loss (charge / discharge loss) during charging and discharging.

[0007] This disclosure describes techniques that can increase the share of renewable energy and stabilize the power supply. [Means for solving the problem]

[0008] A microgrid according to one aspect of the present disclosure includes a first power generation facility that generates first electricity using a first renewable resource that cannot be stored, a storage facility that stores a second renewable resource that can be stored, and a second power generation facility that generates second electricity using the second renewable resource.

[0009] In a microgrid according to one aspect of the present disclosure, first power is generated using a first renewable resource that cannot be stored, and second power is generated using a second renewable resource that can be stored. The second power generation facility uses the stored second renewable resource, allowing for timing adjustment of the generation of the second power. For example, the second power generation facility can generate the second power in a timely manner when there is a supply-demand gap, which is a shortage of the amount of power supplied by the first power relative to the amount of power demand. In this case, the supply-demand gap can be compensated for by the second power generated within the microgrid. This allows for an increase in the renewable energy ratio, which is the ratio of power that can be supplied from the power sources within the microgrid relative to the amount of power demand within the microgrid. Furthermore, the first power and the second power allow for a stable supply of power within the microgrid. Furthermore, because the second renewable resource can be stored as a resource itself, the introduction of an energy storage device can be reduced. For example, the battery capacity of a storage battery can be reduced. The second power can be supplied and consumed without using a storage battery. In other words, compared to the conventional case where a storage battery is used to compensate for the supply-demand gap, the occurrence of charge / discharge losses associated with charging / discharging the storage battery can be suppressed.

[0010] The microgrid may include a resource supply facility that supplies a second renewable resource, which stabilizes the supply and storage of the second renewable resource, thereby providing a more stable power supply within the microgrid.

[0011] The resource supply facility may be a sewage treatment plant. The second renewable resource may include digester gas. The digester gas that would otherwise be discarded is utilized to generate second electricity. This reduces the environmental impact and increases the proportion of renewable energy within the microgrid.

[0012] The main component of the digester gas may be methane. Methane in the digester gas is a biomass fuel produced by fermentation by microorganisms and is a carbon-neutral energy source, which is useful for reducing environmental impact.

[0013] The resource supply facility may be a sawmill. The second renewable resource may include wood chips. The wood chips, which are a biological resource, are used to generate the second electricity. This reduces the environmental impact and increases the proportion of renewable energy in the microgrid.

[0014] The microgrid may also be equipped with a hydrogen storage facility that generates and stores hydrogen using surplus electricity that exceeds the power demand within the microgrid. Hydrogen is generated and stored based on unused surplus electricity. Hydrogen is useful as a means of storing energy because it can be converted into electricity using fuel cells.

[0015] The microgrid may also include a methane storage facility that generates and stores methane using carbon dioxide by-product from the resource supply facility and hydrogen stored in the hydrogen storage facility. Methane is generated and stored from carbon dioxide, a by-product that is not being effectively utilized. Methane is useful for reducing environmental impact.

[0016] The second power generation facility may be operated to generate the second power when the first power is less than a predetermined threshold. The characteristics of the first renewable resource and the second renewable resource complement each other, while the second power generation facility can be kept to a minimum.

[0017] The first power generation facility may be a solar power generation facility that generates a first electric power using sunlight as a first renewable resource. The second power generation facility may operate during the nighttime to generate a second electric power. Since the second power generation facility operates during the nighttime, it can compensate for a decrease in the amount of power generated by the first power generation facility. While the characteristics of the first renewable resource and the second renewable resource complement each other, the operation of the second power generation facility can be kept to a minimum.

[0018] The first power and the second power do not need to be reversely flowed to a power system outside the microgrid, which can increase the proportion of renewable energy in the microgrid.

[0019] The microgrid may include a power storage device that stores the first power. In this case, the power supply can be more stabilized. Also, the microgrid can minimize the storage battery capacity.

[0020] The second power generation facility may generate the second power with a fixed target power output. In this case, fine adjustments to follow the supply-demand gap, which is the shortage of power supply compared to power demand, are not required, and the microgrid can be easily operated. [Effects of the Invention]

[0021] According to the present disclosure, it is possible to provide a technology that can increase the proportion of renewable energy and stabilize the power supply. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram schematically illustrating an example of the configuration of a microgrid according to an embodiment. [Figure 2]FIG. 2 is a graph showing an example of the amount of power demand and the amount of power supply. [Figure 3] FIG. 3 is a diagram schematically illustrating an example of the configuration of a microgrid according to a comparative example. [Figure 4] FIG. 4 is a graph illustrating a theoretical calculation of the relationship between the renewable energy ratio and the storage battery capacity. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicated description will be omitted.

[0024] FIG. 1 is a diagram schematically illustrating an example of the configuration of a microgrid 1 according to an embodiment. The microgrid 1 is connected to an external power system 50. The power system 50 is a power supply facility operated by an electric power company or the like external to the microgrid 1. The microgrid 1 can receive power (power flow) from the power system 50 as needed. The microgrid 1 may also be configured not to supply power to the power system 50 (reverse power flow).

[0025] The microgrid 1 includes a first power generation facility 2, a power storage device 3, a load device 4 (electricity consumer), a resource supply facility 5, a storage facility 6, a second power generation facility 7, a hydrogen storage facility 8, and a methane storage facility 9. The first power generation facility 2, the power storage device 3, the load device 4, the resource supply facility 5, the second power generation facility 7, and the hydrogen storage facility 8 are connected to a power grid L via a switchboard or the like. Each device of the microgrid 1 may be controlled by an EMS 10 (Energy Management System: power control device). The EMS 10 may be located outside the microgrid 1 or inside the microgrid 1.

[0026] The first power generation facility 2 is a facility that generates a first electric power using a first renewable resource that cannot be stored. The first power generation facility 2 supplies the generated first electric power to the microgrid 1. The first renewable resource can also be considered a resource that cannot be controlled by humans. Examples of the first renewable resource include, but are not limited to, solar power and wind power. For example, the first power generation facility 2 may be a photovoltaic (PV) facility that generates the first electric power using solar power as the first renewable resource. The first power generation facility 2 may be a wind power generation facility that generates the first electric power using wind power as the first renewable resource. The first power generation facility 2 may be a combination of a solar power generation facility and a wind power generation facility.

[0027] In one example, when the first power generation facility 2 is a solar power generation facility, the first power generation facility 2 has a plurality of solar panels and a plurality of PCSs (Power Conditioning Systems). The number of solar panels and PCSs is not limited. The PCS is a power conversion device that converts the power generated by the solar panels. The PCS converts the DC power from the solar panels into AC power or a DC voltage of a predetermined voltage.

[0028] The power storage device 3 is a device that stores electrical energy within the microgrid 1. For example, the power storage device 3 may be charged with an excess of the first power generated by the first power generation facility 2. That is, the power storage device 3 may store the surplus first power generated as energy. The power storage device 3 may be charged with power supplied from the power system 50. The power storage device 3 outputs (discharges) power to the load device 4 as needed. The power storage device 3 includes a storage battery, a storage battery PCS, and a monitoring device. The storage battery charges and discharges. The storage battery PCS converts the direct current of the storage battery to alternating current. The monitoring device acquires the remaining energy amount of the storage battery.

[0029] The load device 4 is a device that consumes power within the microgrid 1 and performs a desired operation. Examples of the load device 4 include, but are not limited to, electric lights, power loads, electric vehicles, fuel cell vehicles, and inverter devices. The load device 4 may be configured to operate in cooperation with a load device or the like provided outside the microgrid 1.

[0030] The resource supply facility 5 is a facility or plant that supplies a storable second renewable resource. The resource supply facility 5 consumes some of the power in the microgrid 1 to perform a predetermined process. The second renewable resource may be a by-product produced as a secondary product in the processing step of the resource supply facility 5. The by-product may be biomass fuel. Note that, although the resource supply facility 5 has been described here as consuming some of the power in the microgrid 1 to perform a predetermined process, it may also be configured to perform the predetermined process without consuming power.

[0031] In one example, the resource supply facility 5 may be a sewage treatment plant. In the sewage treatment plant, sludge is decomposed by microorganisms during the sewage treatment process, generating digester gas. The second renewable resource may include digester gas. The main component of digester gas is methane.

[0032] In another example, the resource supply facility 5 may be a sawmill. In the sawmill, wood chips are generated during the wood processing process. The second renewable resource may include wood chips. Examples of wood chips include, but are not limited to, wood chips, pellets, and briquettes.

[0033] The storage facility 6 is a facility that stores a storable second renewable resource. The storage facility 6 stores the second renewable resource supplied from the resource supply facility 5. In other words, the storage facility 6 stores the renewable resource for second power generation as a resource itself. In one example, the storage facility 6 may be a tank that stores digester gas. In another example, the storage facility 6 may be a warehouse that stores wood chips.

[0034] The second power generation facility 7 generates second electricity using a second renewable resource. For example, the second power generation facility 7 generates second electricity using biomass fuel as the second renewable resource. In one example, the second power generation facility 7 may generate second electricity using a gas engine or the like using digester gas stored in the storage facility 6. In another example, the second power generation facility 7 may generate second electricity using a boiler, a gas engine, or the like using wood chips stored in the storage facility 6.

[0035] The hydrogen storage facility 8 generates and stores hydrogen using surplus power that exceeds the power demand in the microgrid 1 and the storage capacity of the power storage device 3. The hydrogen storage facility 8 may include, for example, a water electrolysis device that produces hydrogen by electrolysis of water, and a storage device that stores the produced hydrogen. The hydrogen storage facility 8 may also convert hydrogen into electricity using a fuel cell and supply it to the microgrid 1.

[0036] The methane storage facility 9 generates and stores methane using carbon dioxide by-produced in the resource supply facility 5 and hydrogen stored in the hydrogen storage facility 8. Although the methane generated here cannot be considered a renewable resource, it can be temporarily stored as methane using surplus electricity and used as various energy sources as needed.

[0037] The EMS 10 is a device (control device) that monitors and controls each device in the microgrid 1. For example, the EMS 10 is a computer configured with hardware such as a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and software such as a program stored in the ROM. The EMS 10 may generate control commands for each device in the microgrid 1. The EMS 10 may acquire the amount of power generated and the amount of power consumed in the microgrid 1. The EMS 10 may control the supply of power from the power system 50 to the microgrid 1.

[0038] The microgrid 1 of the present disclosure stabilizes the power supply by using first power generated using a first non-storable renewable resource and second power generated using a storable renewable resource. The microgrid 1 may also stabilize the power supply by using power supplied from at least one of the power storage device 3 and the hydrogen storage facility 8. For example, when the first power and the second power are insufficient for the amount of power demand, the microgrid 1 may stabilize the power supply by using power supplied from at least one of the power storage device 3 and the hydrogen storage facility 8. The first power and the second power may also be configured not to flow back to the power grid 50 outside the microgrid 1.

[0039] Fig. 2 is a graph showing an example of the amount of electricity demand and the amount of electricity supplied. In Fig. 2, the vertical axis represents the amount of electricity, and the horizontal axis represents the time of day. Fig. 2 shows, as the amount of electricity supplied, the amount of electricity generated using solar power P1, the amount of electricity generated using wind power P2, and the amount of electricity discharged from the electricity storage device 3 P3. Fig. 2 also shows a supply-demand gap G, which is the shortage of the amount of electricity supplied relative to the amount of electricity demand D. Part of the supply-demand gap G is made up for by the amount of electricity discharged P3.

[0040] The microgrid 1 of the present disclosure compensates for part or all of the supply-demand gap G with the second power. The second power generation facility 7 may generate the second power during the time period when the supply-demand gap G exists.

[0041] If the first power generation facility 2 is a solar power generation facility, the second power generation facility 7 may operate during the nighttime to generate the second electric power. The nighttime may be a time period that includes at least a portion of the time period from after sunset to before sunrise. The nighttime may be a fixed time period. For example, the second power generation facility 7 may divide 24 hours into three time periods and generate the second electric power during time periods when there is a large shortage of the amount of power generated using solar light P1. In one example, the second power generation facility 7 may operate for 16 hours from 5:00 PM to 8:00 AM to generate the second electric power.

[0042] The second power generation facility 7 may generate the second power with a fixed target power generation amount. For example, the fixed value may be the average value of the supply-demand gap G, which is the difference between the first power and the amount of power demand during the nighttime. Note that the supply-demand gap G varies depending on the time of day. The second power generation facility 7 may generate the second power without tracking the variation.

[0043] The second power generation facility 7 may operate and generate the second power when the first power is less than a predetermined threshold. The second power generation facility 7 may generate the second power based on operational performance. For example, if the first power during a specific time period tends to be less than a predetermined threshold, the second power generation facility 7 may generate the second power during the specific time period.

[0044] FIG. 3 is a diagram schematically illustrating an example of the configuration of a microgrid 100 according to a comparative example. The microgrid 100 includes a first power generation facility 20, a power storage device 30, and a load device 40. The first power generation facility 20 has the same configuration as the first power generation facility 2. The power storage device 30 has the same configuration as the power storage device 3. The load device 40 has the same configuration as the load device 4. The microgrid 100 does not supply second power. The microgrid 100 compensates for the supply-demand gap with discharged power from the power storage device 30 (specifically, a storage battery).

[0045] Figure 4 is a graph illustrating an example of a theoretical calculation of the relationship between the renewable energy ratio and battery capacity. In Figure 4, the vertical axis represents the renewable energy ratio, and the horizontal axis represents the battery capacity. The renewable energy ratio is the ratio of the power demand within the microgrid that can be supplied from the power sources within the microgrid. For example, a renewable energy ratio of 70% indicates that 70% of the power is derived from renewable resources and 30% is purchased from an external power system (e.g., power system 50).

[0046] FIG. 4 shows a desk-top calculation value R of the microgrid 1 according to the embodiment and a desk-top calculation value C of the microgrid 100 according to the comparative example. For an equivalent renewable energy ratio, the storage battery capacity in the desk-top calculation value C is larger than the storage battery capacity in the desk-top calculation value R. In one example, when the renewable energy ratio is approximately 75%, the storage battery capacity in the desk-top calculation value R is 4 [MWh]. In contrast, when the renewable energy ratio is approximately 75%, the storage battery capacity in the desk-top calculation value C is 8 [MWh]. In this way, the microgrid 1 can obtain a high renewable energy ratio while suppressing the storage battery capacity compared to the microgrid 100 according to the comparative example.

[0047] As described above, a microgrid 1 according to one aspect of the present disclosure includes a first power generation facility 2 that generates first electricity using a first renewable resource that cannot be stored, a storage facility 6 that stores a second renewable resource that can be stored, and a second power generation facility 7 that generates second electricity using the second renewable resource.

[0048] In a microgrid 1 according to one aspect of the present disclosure, first power is generated using a first renewable resource that cannot be stored, and second power is generated using a second renewable resource that can be stored. The second power generation facility 7 uses the stored second renewable resource, allowing for timing adjustment of the generation of the second power. For example, the second power generation facility 7 can generate the second power in a timely manner when there is a supply-demand gap, which is a shortage of the first power supply relative to the power demand. In this case, the supply-demand gap can be compensated for by the second power generated within the microgrid 1. This allows for an increase in the renewable energy ratio, which is the ratio of power that can be supplied from the power sources within the microgrid 1 relative to the power demand within the microgrid 1. Furthermore, the first power and the second power allow for a stable supply of power within the microgrid 1. Furthermore, because the second renewable resource can be stored as a resource itself, the introduction of an energy storage device can be reduced. For example, the storage capacity of a storage battery can be reduced. The second power can be supplied and consumed without using a storage battery. In other words, compared to the conventional case where a storage battery is used to compensate for the supply-demand gap, the occurrence of charge / discharge losses associated with charging / discharging the storage battery can be suppressed.

[0049] The microgrid 1 includes a resource supply facility 5 that supplies a second renewable resource. The resource supply facility 5 stabilizes the supply and storage of the second renewable resource. As a result, the power supply within the microgrid 1 can be made more stable.

[0050] The resource supply facility 5 is a sewage treatment plant. The second renewable resource includes digester gas. The digester gas that would have been discarded is used to generate second electricity. This reduces the environmental load and increases the proportion of renewable energy in the microgrid 1.

[0051] The main component of digester gas is methane, a biomass fuel produced by microbial fermentation and other processes, and is a carbon-neutral energy source, making it useful for reducing environmental impact.

[0052] The resource supply facility 5 is a sawmill. The second renewable resource includes wood chips. The wood chips, which are a biological resource, are used to generate the second power. This reduces the environmental load and increases the proportion of renewable energy in the microgrid 1.

[0053] The microgrid 1 is equipped with a hydrogen storage facility 8 that generates and stores hydrogen using surplus electricity that exceeds the electricity demand within the microgrid 1. Hydrogen is generated and stored based on surplus electricity that is not being used effectively. Hydrogen is useful as a means of storing energy because it can be converted into electricity using fuel cells.

[0054] The microgrid 1 is equipped with a methane storage facility 9 that generates and stores methane using carbon dioxide, a by-product of the resource supply facility, and hydrogen stored in a hydrogen storage facility 8. Methane is generated and stored based on carbon dioxide, a by-product that is not being effectively utilized. Methane is useful for reducing environmental impact.

[0055] The second power generation facility 7 operates to generate the second power when the first power is less than a predetermined threshold. The characteristics of the first renewable resource and the second renewable resource complement each other, and the operation of the second power generation facility 7 can be kept to a minimum.

[0056] The first power generation facility 2 is a solar power generation facility that generates a first electric power using sunlight as a first renewable resource. The second power generation facility 7 operates at night to generate a second electric power. Because the second power generation facility 7 operates at night, it can compensate for a decrease in the amount of power generated by the first power generation facility 2. While the characteristics of the first renewable resource and the second renewable resource complement each other, the operation of the second power generation facility 7 can be kept to a minimum.

[0057] The first power and the second power do not flow back to the power system 50 outside the microgrid. In this case, the proportion of renewable energy in the microgrid 1 can be increased.

[0058] The microgrid 1 includes a power storage device 3 that stores the first power. In this case, the power supply can be further stabilized. Furthermore, the microgrid 1 can minimize the storage battery capacity.

[0059] The second power generation facility 7 generates the second electric power with a fixed target power generation amount. In this case, fine adjustments to follow the supply-demand gap, which is the shortage of power supply compared to power demand, are not required, and the microgrid 1 can be easily operated.

[0060] [Variations] The present disclosure is not necessarily limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

[0061] In the above embodiment, an example in which there is only one microgrid 1 has been described, but this is not limiting. For example, multiple microgrids may be combined. In one example, the microgrid 1 may be connected to one or more other microgrids. The one or more other microgrids may not include the second power generation equipment 7. The one or more other microgrids may have the same configuration as the microgrid 1 except for the second power generation equipment 7. The second power generation equipment 7 may generate second power to fill the supply-demand gap of each of the multiple microgrids. When the timing of each supply-demand gap differs, the second power generation equipment 7 can be operated continuously. Since the number of times the second power generation equipment 7 is operated and stopped can be reduced, the power generation efficiency of the second power is improved.

[0062] In the above embodiment, an example has been described in which the microgrid 1 includes the hydrogen storage facility 8 and the methane storage facility 9, but this is not limiting. The microgrid 1 does not necessarily need to include the hydrogen storage facility 8 and the methane storage facility 9.

[0063] [Note] The following is a summary of the present disclosure. [1] a first power generation facility that generates first electricity using a first non-storable renewable resource; a storage facility for storing the storable second renewable resource; and a second power generation facility that generates second electricity using the second renewable resource. Microgrid. [2] The microgrid according to [1], further comprising a resource supply facility that supplies the second renewable resource. [3] the resource supply facility is a sewage treatment plant, The second renewable resource comprises digester gas. [2] The microgrid described in [2]. [4] The microgrid according to [3], wherein the main component of the digestion gas is methane. [5] the resource supply facility is a sawmill, The second renewable resource comprises wood chips; [2] The microgrid described in [2]. [6] The microgrid according to any one of [2] to [5], further comprising a hydrogen storage facility that generates and stores hydrogen using surplus power that exceeds the power demand within the microgrid. [7] The microgrid according to [6], further comprising a methane storage facility that generates and stores methane using carbon dioxide by-produced from the resource supply facility and the hydrogen stored in the hydrogen storage facility. [8] The microgrid according to any one of [1] to [7], wherein the second power generation facility operates to generate the second power when the first power is less than a predetermined threshold. [9] the first power generation facility is a solar power generation facility that generates the first electric power using sunlight as the first renewable resource; The second power generation facility operates during the nighttime to generate the second electric power. The microgrid according to any one of [1] to [7].

[10] The microgrid according to any one of [1] to [9], wherein the first power and the second power do not flow back to an electric power system outside the microgrid.

[11] The microgrid according to any one of [1] to

[10] , further comprising a power storage device that stores the first power.

[12] The microgrid according to any one of [1] to

[11] , wherein the second power generation facility generates the second power with a fixed value of the amount of power generation as a target. [Explanation of symbols]

[0064] 1. Microgrid 2. No. 1 Power Plant 3. Energy storage device 4 Load device 5 Resource supply equipment 6. Storage facilities 7. Second Power Plant 8 Hydrogen storage facilities 9. Methane storage facility 10 EMS 50 Power system

Claims

1. a first power generation facility that generates first electricity using a first renewable resource that cannot be stored; a storage facility for storing the storable second renewable resource; a second power generation facility that generates second electricity using the second renewable resource; Microgrid.

2. The microgrid of claim 1 , comprising a resource supply facility that supplies the second renewable resource.

3. the resource supply facility is a sewage treatment plant, The second renewable resource comprises digester gas. The microgrid of claim 2 .

4. The microgrid of claim 3 , wherein the digester gas is primarily composed of methane.

5. the resource supply facility is a sawmill, The second renewable resource comprises wood chips; The microgrid of claim 2 .

6. The microgrid according to claim 2 , further comprising a hydrogen storage facility that generates and stores hydrogen using surplus power that exceeds the power demand within the microgrid.

7. The microgrid according to claim 6, further comprising a methane storage facility that generates and stores methane using carbon dioxide by-produced from the resource supply facility and the hydrogen stored in the hydrogen storage facility.

8. The microgrid according to claim 1 , wherein the second power generation facility operates to generate the second power when the first power is less than a predetermined threshold.

9. the first power generation facility is a solar power generation facility that generates the first electric power using sunlight as the first renewable resource, The second power generation facility operates during the nighttime to generate the second electric power. The microgrid of claim 1 .

10. The microgrid according to claim 1 , wherein the first power and the second power do not flow back to a power system outside the microgrid.

11. The microgrid according to claim 1 , further comprising a power storage device that stores the first power.

12. The microgrid according to claim 1 , wherein the second power generation facility generates the second power with a fixed target amount of power generation as a target.

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