Power system and server

Abstract

When the microgrid is switched from the independent operation to the interconnected operation with the power grid, the CEMS server determines the first master DER and the slave device based on the master schedule, and performs master-slave control. When the first master DER is down, the CEMS server compares the remaining capacities of the electric storage type DERs included in the DER group (S27). The CEMS server then determines, among the electric storage type DERs included in the DER group, the DER having the highest remaining capacity as the second master DER (S29), and performs master-slave control (S31).

Description

[0001] This non-provisional application is based on Japanese Patent Application No. 2020-213628, filed with the Japan Patent Office on December 23, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to power systems and servers. Background Technology

[0003] Japanese Patent Application Publication No. 2020-028198 discloses a control system for managing the supply and demand of a microgrid interconnected with an external power grid. This control system uses multiple power regulation resources (e.g., distributed power sources, loads, and flywheel-equipped sensors) that can be electrically connected to the microgrid to manage its supply and demand. When power supply from the external power grid to the microgrid is stopped, the loads electrically connected to the microgrid are disconnected according to priority, and power is replenished by the flywheel-equipped sensors. Summary of the Invention

[0004] In the interconnected operation of a microgrid with an external power grid, current control is applied to multiple power regulation resources based on the frequency of the external power grid to synchronize with its power supply. Conversely, in the independent operation of a microgrid, the frequency within the microgrid needs to be determined for controlling multiple power regulation resources.

[0005] For example, it is conceivable that during the independent operation of a microgrid, power conditioning resources used as master devices at a specific frequency can be predetermined, other power conditioning resources can be designated as slave devices, and master-slave control can be performed. However, if the power conditioning resources used as master devices stop (go down) for some reason, the independent operation of the microgrid cannot be properly performed.

[0006] This disclosure is made to address the aforementioned problems. The purpose of this disclosure is to properly implement the independent operation of the power grid.

[0007] A power system according to one aspect of this disclosure includes: a plurality of power conditioning resources electrically connected to a first power grid and a management device for managing the power of the first power grid. The first power grid is configured to be connected to and disconnected from the second power grid. When the first power grid is connected to the second power grid and operates in an interconnection with the second power grid, the management device performs current control of the plurality of power conditioning resources to synchronize with the frequency of the second power grid. When the first power grid is disconnected from the second power grid and operates independently, the management device determines a predetermined power conditioning resource as a master device, determines power conditioning resources other than the predetermined power conditioning resource as slave devices, and performs master-slave control of the plurality of power conditioning resources, wherein the predetermined power conditioning resource is a power conditioning resource pre-determined among the plurality of power conditioning resources. When the predetermined power conditioning resource cannot operate in the independent operation of the first power grid, the management device determines a master device from the plurality of power conditioning resources based on information about the quantity of power of the plurality of power conditioning resources, determines power conditioning resources other than the determined master device as slave devices, and performs master-slave control of the plurality of power conditioning resources.

[0008] Using the above configuration, even if the predetermined power adjustment resources for the master equipment are unavailable during the independent operation of the first power grid, the master equipment can be selected from multiple power adjustment resources, and master-slave control can be performed. Even if the predetermined power adjustment resources are unavailable during the independent operation of the first power grid, the independent operation of the first power grid can still be appropriately performed.

[0009] In one embodiment, the information regarding the amount of electricity is information indicating the current energy storage capacity. In master-slave control, the management device identifies the power regulation resource with the highest energy storage capacity among multiple power regulation resources as the master device, and identifies the power regulation resources other than the identified master device as slave devices.

[0010] With the above configuration, since the power regulation resource with the highest storage capacity among multiple power regulation resources is determined as the master device, master-slave control can be performed for a longer period of time compared to when the power regulation resource with the lower storage capacity is determined as the master device.

[0011] In one embodiment, in master-slave control, when the energy storage capacity of the master device drops below a threshold capacity, the management device will identify the slave device with the highest energy storage capacity among the slave devices as the new master device, and identify the power adjustment resources that have been used as the master device as slave devices.

[0012] Using the above configuration, since a new master device is selected when the storage capacity of the master device drops below the threshold capacity, master-slave control can continue even when the storage capacity of the master device decreases. In other words, the independent operation of the first power grid can continue appropriately without stopping its independent operation.

[0013] In one embodiment, the information regarding the quantity of electricity is information indicating the state of charge (SOC). In master-slave control, the management device determines the power conditioning resource with the highest SOC among multiple power conditioning resources as the master device, and determines the power conditioning resources other than the determined master device as slave devices.

[0014] With the above configuration, since the power regulation resource with the highest SOC among multiple power regulation resources is determined as the master device, master-slave control can be performed for a longer period of time compared to when the power regulation resource with a lower SOC is determined as the master device.

[0015] In one embodiment, in master-slave control, when the SOC of the master device drops below a threshold SOC, the management device will identify the slave device with the highest SOC among the slave devices as the new master device and identify the power conditioning resources that have been used as the master device as slave devices.

[0016] Using the above configuration, since a new master device is determined when the master device's SOC drops below the threshold capacity, master-slave control can continue even when the master device's SOC decreases. In other words, the independent operation of the first power grid can continue appropriately without halting its independent operation.

[0017] According to another aspect of this disclosure, a server manages the power of a first power grid electrically connected to multiple power adjustment resources. The first power grid is configured to connect to and disconnect from a second power grid. The server includes a memory storing information about the quantity of power of the multiple power adjustment resources and a controller. When the first power grid is connected to the second power grid and performs interconnection operation with the second power grid, the controller performs current control of the multiple power adjustment resources to synchronize with the frequency of the second power grid. When the first power grid is disconnected from the second power grid and performs independent operation, the controller determines a predetermined power adjustment resource as a master device, determines power adjustment resources other than the predetermined power adjustment resource as slave devices, and performs master-slave control of the multiple power adjustment resources, wherein the predetermined power adjustment resource is a power adjustment resource pre-determined among the multiple power adjustment resources. When the predetermined power adjustment resource cannot operate during independent operation of the first power grid, the controller determines a master device from the multiple power adjustment resources based on information about the quantity of power, determines power adjustment resources other than the determined master device as slave devices, and performs master-slave control of the multiple power adjustment resources.

[0018] The foregoing and other objects, features, aspects and advantages of this disclosure will become more apparent from the following detailed description of this disclosure when taken in conjunction with the accompanying drawings. Attached Figure Description

[0019] Figure 1 A schematic configuration of a power system according to an embodiment is shown.

[0020] Figure 2 This is a functional block diagram showing the components of the CEMS server according to their functions.

[0021] Figure 3 This is a flowchart illustrating the processes performed by the CEMS server during the interconnection operation of a microgrid.

[0022] Figure 4 This is a flowchart illustrating the processes performed by the CEMS server during the independent operation of the microgrid.

[0023] Figure 5 It is shown Figure 4 The detailed processing flowchart of S31.

[0024] Figure 6 This is a flowchart illustrating the process performed by the CEMS server during the independent operation of the microgrid in Variation 1.

[0025] Figure 7 It is shown Figure 6 The detailed processing flowchart of S55. Detailed Implementation

[0026] Embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. Furthermore, identical or equivalent parts in the drawings are labeled with the same reference numerals, and their descriptions will not be repeated.

[0027] [Example]

[0028] <Overall Configuration of Power System>

[0029] Figure 1 A schematic configuration of a power system according to an embodiment is shown. Power system 1 includes a power grid PG, a microgrid MG, a Community Energy Management System (CEMS) server 100, a power transmission and distribution operator server 200, a distributed energy resource (DER) group 500, and power receiving and conversion facilities 501.

[0030] A microgrid (MG) is a power network that supplies electricity to a city as a whole (e.g., a smart city). Power supply and demand within the microgrid (MG) are managed by the CEMS server 100. The power lines used to network multiple DERs within the microgrid (MG) can be independent power lines. The microgrid (MG) is configured to connect to and disconnect from the power grid (PG).

[0031] The power transmission and distribution operator server 200 is a computer that manages the supply and demand of the power grid PG. The power grid PG is a power network consisting of power plants (not shown) and power transmission and distribution facilities. In this embodiment, the power company acts as both the power generation operator and the power transmission and distribution operator. The power company corresponds to a general power transmission and distribution operator and maintains and manages the power grid PG (commercial power grid). The power company corresponds to the administrator of the power grid PG. The power transmission and distribution operator server 200 belongs to the power company.

[0032] The power receiving and conversion facility 501 is located at the interconnection point (power receiving point) of the microgrid MG and is configured to switch between connection (parallel connection) and disconnection (parallel disconnection) between the power grid PG and the microgrid MG. The power receiving and conversion facility 501 is located at the connection point between the microgrid MG and the power grid PG.

[0033] When the microgrid MG operates in interconnection mode while connected to the power grid PG, the power receiving and conversion facility 501 receives alternating current (AC) power from the power grid PG, steps down the received power, and supplies the stepped-down power to the microgrid MG. When the microgrid MG operates independently while disconnected from the power grid PG, power is not supplied from the power grid PG to the microgrid MG. The power receiving and conversion facility 501 includes high-voltage side (primary side) switches (e.g., sectionalizing switches, isolators, circuit breakers, and load switches), transformers, protective relays, measuring instruments, and controllers. The CEMS server 100 is configured to receive information (e.g., power waveforms) from the power receiving and conversion facility 501 and to indicate the connection and disconnection of the power receiving and conversion facility 501.

[0034] CEMS server 100 is configured to communicate with each of the power transmission and distribution operator server 200 and DER group 500. The communication protocol may be OpenADR. DER group 500 includes multiple DERs that can be electrically connected to the microgrid MG. CEMS server 100 is configured to manage the multiple DERs included in DER group 500. When a request to adjust the supply and demand of the power grid PG is received from power transmission and distribution operator server 200, CEMS server 100 can perform a Demand Response (DR) on DER group 500. CEMS server 100 can perform DR on DER group 500 in response to requests from the supply and demand adjustment market. CEMS server 100 can perform DR on DER group 500 to adjust the supply and demand of the microgrid MG.

[0035] DER group 500 includes Electric Vehicle Supply Equipment (EVSE) 20, homes 30, commercial facilities 40, factories 50, Energy Storage Systems (ESS) 60, Fuel Cell Systems (FCS) 70, generators 80, and variable renewable energy sources 90. Each of these can be used as a DER. Multiple DERs included in DER group 500 are electrically interconnected via microgrids (MG).

[0036] DER group 500 further includes battery electric vehicles (BEVs) 11 and fuel cell electric vehicles (FCEVs) 12. EVSE 20 is used as a DER when electrically connected to a vehicle (e.g., a BEV or FCEV). For example, when the charging connector of EVSE 20 is inserted (plufted) into the vehicle's inlet, EVSE 20 and the vehicle are electrically connected to each other.

[0037] DER group 500 may include any number of vehicles. DER group 500 may include personally owned vehicles (POVs) or Mobility as a Service (MaaS) vehicles. MaaS vehicles are vehicles managed by a MaaS entity. DER group 500 may include any number of EVSEs 20, homes 30, commercial facilities 40, factories 50, ESSs 60, FCSs 70, generators 80, and variable renewable energy sources 90. Each DER included in DER group 500 corresponds to an example of "Electricity Adjustment Resources" according to this disclosure.

[0038] BEV 11 includes an electronic control unit (ECU) 10a, a battery B1, and a communication device C1. ECU 10a is configured to control each device mounted on BEV 11. Communication device C1 is configured to communicate wirelessly with CEMS server 100. Battery B1 includes a secondary battery such as a nickel-metal hydride battery or a lithium-ion battery. The electricity stored in battery B1 is used to power a motor (not shown) for the BEV 11's movement or to power each device mounted on BEV 11.

[0039] The FCEV 12 includes an ECU 10b, a generator H2, a battery B2, and a communication device C2. The generator H2 includes a hydrogen tank (not shown) in which hydrogen is stored and a fuel cell (not shown) that generates electricity through a chemical reaction between hydrogen and oxygen. The fuel cell generates electricity using hydrogen supplied from the hydrogen tank. The electricity generated by the generator H2 is used to drive a motor (not shown) for the FCEV 12's movement, to power each device mounted on the FCEV 12, or is stored in the battery B2. Users of the FCEV 12 can refill hydrogen at hydrogen stations (not shown) located in cities. The communication device C2 is configured to communicate wirelessly with the CEMS server 100. The battery B2 includes a secondary battery, such as a nickel-metal hydride battery or a lithium-ion battery. The electricity stored in the battery B2 is used to drive a motor (not shown) for the FCEV 12's movement or to power each device mounted on the FCEV 12.

[0040] EVSE 20 is, for example, a charging facility installed in a city. EVSE 20 is a public EVSE that vehicle users can use after pre-approval. Authentication methods can be via charging card authentication or via communication authentication (e.g., plug and charge). In this embodiment, DER group 500 includes multiple EVSE 20s.

[0041] House 30 includes various household electrical appliances (e.g., lighting fixtures, air conditioning facilities, kitchen appliances, information equipment, televisions, refrigerators, and washing machines). House 30 may also include at least one of a charger-discharger (e.g., a home EVSE), variable renewable energy (e.g., rooftop photovoltaic panels), ESS, FCS, and cogeneration system (e.g., a water heater or heat pump water heater that uses heat generated in self-generated electricity). For example, the supply and demand of energy in house 30 is managed by a Home Energy Management System (HEMS) not shown. Microgrid MG and house 30 are interconnected to supply and receive electricity therebetween. In this embodiment, CEMS server 100 and each house 30 communicate with each other via HEMS. In this embodiment, DER group 500 includes multiple houses 30.

[0042] Commercial facility 40 includes, for example, office buildings and shops. Examples of shops include department stores, shopping malls, supermarkets, or convenience stores. Energy supply and demand in each facility included in commercial facility 40 are managed, for example, through a Building Energy Management System (BEMS) not shown. The BEMS can manage energy supply and demand individually for each facility, or it can manage energy supply and demand collectively across multiple facilities. Each facility included in commercial facility 40 and a microgrid MG are interconnected to supply and receive power among themselves. In this embodiment, CEMS server 100 communicates with commercial facility 40 via the BEMS.

[0043] Factory 50 may be, for example, an automobile factory or other factory. Factory 50 includes, for example, production lines and a centralized heat source for air conditioning. Factory 50 may also include at least one of variable renewable energy sources (e.g., photovoltaic or wind power facilities), EVSE, ESS, FCS, generators (e.g., gas turbine generators or diesel generators), and a combined heat and power system. The supply and demand of energy in factory 50 is managed, for example, by a Factory Energy Management System (FEMS) not shown. Microgrid MG and factory 50 are interconnected to supply and receive power between them. In this embodiment, CEMS server 100 communicates with factory 50 via FEMS.

[0044] The ESS 60 includes stationary batteries configured to be rechargeable and dischargeable to the microgrid MG. For example, the batteries included in the ESS 60 can be lithium-ion batteries, lead-acid batteries, nickel-metal hydride batteries, redox flow batteries, or sodium-sulfur (NAS) batteries. Surplus electricity generated by the variable renewable energy source 90 can be stored in the ESS 60.

[0045] FCS 70 includes a stationary fuel cell that generates electricity through a chemical reaction between hydrogen and oxygen. FCS 70 is connected to a hydrogen tank 71. Hydrogen tank 71 is connected to a hydrogen generator 72. FCS 70 is configured to generate electricity using hydrogen supplied from hydrogen tank 71 and to supply the generated electricity to the microgrid MG. Hydrogen generator 72 can employ any method. For example, hydrogen generator 72 can employ known methods such as byproduct hydrogen methods, water electrolysis, fossil fuel reforming methods, biomass reforming methods, or iodine-sulfur (IS) processes. Hydrogen generator 72 can generate hydrogen by using electricity supplied from the microgrid MG or by using surplus electricity generated by variable renewable energy source 90. CEMS server 100 can control hydrogen generator 72 such that the remaining amount of hydrogen in hydrogen tank 71 does not decrease below a predetermined value.

[0046] Generator 80 is a stationary generator that produces electricity using fossil fuels. Generator 80 can be, for example, a gas turbine generator or a diesel generator. Generator 80 can be used as an emergency power source.

[0047] Variable renewable energy 90 is a power source whose generated electricity output varies according to weather conditions, and which supplies the generated electricity to a microgrid (MG). Variable renewable energy 90 includes, for example, photovoltaic (PV) power generation facilities and wind power generation facilities. The electricity generated by variable renewable energy 90 corresponds to Variable Renewable Energy (VRE).

[0048] CEMS server 100 includes a processor 110, a memory 120, and a communication device 130. The processor 110, memory 120, and communication device 130 are interconnected via a bus 140. The processor 110 may be a Central Processing Unit (CPU). The memory 120 is configured to store various types of information. The memory 120 stores programs executed by the processor 110, as well as information to be used by the programs (e.g., mappings, mathematical expressions, and various parameters). The communication device 130 includes various communication interfaces (I / F). CEMS server 100 is configured to communicate with external systems via the communication device 130.

[0049] The CEMS server 100 controls the DER group 500 connected to the microgrid MG to function as a virtual power plant (VPP). More specifically, the CEMS server 100 remotely controls and integrates the DER group 500 based on energy management technology utilizing the Internet of Things (IoT), enabling the DER to operate like a single power plant.

[0050] In this embodiment, the administrator of the microgrid MG has an electricity contract with the power company. The power company supplies electricity to the microgrid MG according to the electricity contract. Under this electricity contract, the amount of electricity supplied from the power grid PG to the microgrid MG is determined. This electricity will be referred to as "contract electricity" below. "The supplied electricity satisfies the contract electricity" means that the supplied electricity is neither more nor less than the contract electricity (including within the range determined as contract electricity).

[0051] When a microgrid MG is connected to a power grid PG and performs interconnection operations with the PG, the CEMS server 100 is configured to adjust the power supply and demand of the microgrid MG so that the power supplied from the power grid PG to the microgrid MG meets the contracted power requirements. During the interconnection operation of the microgrid MG, the CEMS server 100 controls the DER, which acts as the regulating force of the microgrid MG, thereby adjusting the power supply and demand. The DER used as the regulating force of the microgrid MG will also be referred to as the "regulating force DER" below.

[0052] When power supply from the grid PG is stopped and the microgrid MG operates independently, the CEMS server 100 is configured to adjust the power supply and demand of the microgrid MG without receiving power from the grid PG. During the independent operation of the microgrid MG, the CEMS server 100 controls the regulating force DER to adjust the power supply and demand.

[0053] Below, please refer to the specific details. Figure 1 and Figure 2 This will describe the control of the regulating force DER during interconnected operation and stand-alone operation of the microgrid MG.

[0054] Figure 2 This is a functional block diagram showing the components of the CEMS server 100 according to their functions. (Reference) Figure 2 and Figure 1 The processor 110 of the CEMS server 100 includes an information management unit 111, a runtime switching unit 113, an interconnect runtime unit 115, and a stand-alone runtime unit 117. For example, the processor 110 functions as the information management unit 111, runtime switching unit 113, interconnect runtime unit 115, and stand-alone runtime unit 117 by executing programs stored in the memory 120. The information management unit 111, runtime switching unit 113, interconnect runtime unit 115, and stand-alone runtime unit 117 can be implemented, for example, using dedicated hardware (electronic circuitry).

[0055] Information management unit 111 manages information about DERs registered with CEMS server 100 (hereinafter also referred to as "resource information"). Identification information (ID) is assigned to each DER included in DER group 500 and stored in memory 120. Information management unit 111 collects information about each DER, updates the resource information for each predetermined control cycle, and causes memory 120 to store the updated resource information.

[0056] EVSE 20, housing 30, commercial facilities 40, factories 50, ESS 60, FCS 70, generators 80, and variable renewable energy sources 90 register with CEMS server 100 as fixed DERs. Furthermore, vehicles (BEV 11 and FCEV 12) register with CEMS server 100 as mobile DERs. Vehicles connect to EVSE 20 to function as DERs.

[0057] Resource information includes information on the amount of electricity generated by each DER. This information includes indications of the electricity consumed by each of the houses 30, commercial facilities 40, and factories 50. It also includes information indicating the SOC of the ESS60's battery, the amount of electricity used for charging and discharging, and the remaining capacity (kWh). Furthermore, it includes information indicating the amount of electricity generated by the FCS 70 and the remaining amount of hydrogen in the hydrogen tank 71. Finally, it includes information indicating the amount of electricity generated by each of the generators 80 and the variable renewable energy sources 90.

[0058] Information regarding the amount of electricity also includes information indicating the State of Charge (SOC) of battery B1 of BEV 11 connected to EVSE 20, information indicating the charging and discharging power of battery B1, and information indicating the remaining capacity (kWh) of battery B1. Information regarding the amount of electricity also includes information indicating the remaining amount of hydrogen in generator H2 of FCEV 12 connected to EVSE 20, information indicating the amount of electricity generated by generator H2, information indicating the State of Charge (SOC) of battery B2, and information indicating the charging and discharging power of battery B2.

[0059] Resource information may include information indicating the running status of each DER (whether it is running or stopped). CEMS server 100 can communicate with each fixed DER to obtain resource information.

[0060] DERs included in DER group 500 are classified as power generation DERs, energy storage DERs, and load DERs.

[0061] In a generator-type DER, a generator produces electricity using a predetermined fuel (e.g., light oil, natural gas, or hydrogen) and supplies the generated electricity to a microgrid MG via a power conversion circuit. In a storage-type DER, power is exchanged between a battery and the microgrid MG via a power conversion circuit. The power conversion circuit in each DER is configured to operate according to control signals from a CEMS server 100 and perform predetermined power conversions. In this embodiment, the power conversion circuit includes an inverter and a phase-locked loop (PLL). The power conversion circuit may include a relay that switches between connection and disconnection between the DER and the microgrid MG.

[0062] For example, in Figure 1 In the DER group 500 shown, ESS 60 is used as a storage-type DER. Each of FCS 70, generator 80, and variable renewable energy 90 is used as a generation-type DER. Although the electricity generated by variable renewable energy 90 is largely dependent on weather conditions, the power output of variable renewable energy 90 can be limited.

[0063] BEV 11 functions as a storage-type DER by charging and discharging battery B1 connected to the microgrid MG. FCEV 12 functions as a generation-type DER by supplying power generated by generator H2 to the microgrid MG. FCEV 12 can be configured as a storage-type DER. FCEV 12 can also function as a storage-type DER when the capacity and charging / discharging performance of battery B2 are sufficient. The power conversion circuitry can be mounted on the vehicle (BEV 11 or FCEV 12) or on the EVSE 20. For example, direct-current (DC) power can be supplied from the vehicle to the DC-type EVSE 20, and the inverter included in the EVSE 20 can perform DC / AC conversion. The on-board inverter can perform DC / AC conversion on power discharged from the battery included in the vehicle, and the resulting AC power can be supplied from the vehicle to the AC-type EVSE.

[0064] Although Figure 2 Not shown, but electrical equipment consuming power from the microgrid MG can also be used as a DER. The higher the electrical load of the equipment connected to the microgrid MG, the greater the power consumption in the microgrid MG. For example, Figure 1 The demand side of each of the houses 30, commercial facilities 40 and factories 50 shown can adjust the supply and demand of the microgrid MG by adjusting the electrical load of the electrical equipment.

[0065] The information management unit 111 collects information about each DER, updates the resource information for each predetermined control cycle, and stores the updated resource information in the memory 120.

[0066] Operation switching unit 113 determines the switch between interconnected operation and stand-alone operation of the microgrid MG and provides notifications to interconnected operation unit 115 and stand-alone operation unit 117. During interconnected operation of the microgrid MG, operation switching unit 113 monitors whether a fault has occurred in the power grid PG. Such monitoring is performed repeatedly, for example, for each predetermined control cycle. A fault refers to, for example, the inability to supply power from the power grid PG to the microgrid MG due to a power outage, power failure, etc. When no fault has occurred in the power grid PG, operation switching unit 113 provides a first notification to interconnected operation unit 115. The first notification is a notification instructing interconnected operation. Upon receiving the first notification, interconnected operation unit 115 continues with current control as described below. When a fault has occurred in the power grid PG, operation switching unit 113 provides a second notification to stand-alone operation unit 117. The second notification is a notification instructing stand-alone operation. Upon receiving the second notification, stand-alone operation unit 117 begins master-slave control as described below.

[0067] During the independent operation of the microgrid MG, the operation switching unit 113 monitors the recovery of the faulty power grid PG. Such monitoring is performed repeatedly, for example, for each predetermined control cycle. When the power grid PG has not yet recovered, the operation switching unit 113 provides a second notification to the independent operation unit 117. Upon receiving the second notification, the independent operation unit 117 continues the master-slave control described below. When the power grid PG has recovered, the operation switching unit 113 provides a first notification to the interconnected operation unit 115. Upon receiving the first notification, the interconnected operation unit 115 begins current control as described below.

[0068] During the interconnection operation of the microgrid MG, the interconnection operation unit 115 adjusts the supply and demand of the microgrid MG and the power grid PG by performing current control of the regulating force DER. The regulating force DER includes, for example, a power conversion circuit including an inverter and a PLL. The interconnection operation unit 115 uses the PLL of the regulating force DER to detect the amplitude and phase of the voltage waveform of the power grid PG and controls the inverter of the regulating force DER to synchronize the power of the microgrid MG with the power of the power grid PG. The interconnection operation unit 115 controls the AC current through the inverter of the regulating force DER, providing feedback on the current detection value while making the current flowing through the microgrid MG follow the target current value. More specifically, the interconnection operation unit 115 divides the current flowing through the microgrid MG into active current components and reactive current components, and controls the voltage output from the inverter of the regulating force DER so that each of the active current component and the reactive current component reaches the target current value. The current control of the regulating force DER can be performed interconnected with FMES, HEMS, BEMS, ECU, etc.

[0069] During the independent operation of the microgrid MG, the independent operation unit 117 adjusts the supply and demand of the microgrid MG by executing master-slave control of the regulating force DER. The DERs used as master devices in the master-slave control are predetermined and stored in memory 120. The information indicating the DERs used as master devices will be referred to as the "master plan" below. For example, fixed DERs such as ESS 60, FCS 70, or generator 80 are selected as the DERs determined to be master devices. When the slave operation switching unit 113 receives a second notification (a notification indicating independent operation), the independent operation unit 117 reads the master plan from memory 120 and determines the DERs specified in the master plan as master devices, while determining the other DERs as slave devices.

[0070] In the master-slave control performed by the independent operating unit 117, the master device electrically connected to the microgrid MG performs voltage control through a power conversion circuit (including an inverter), and each slave device electrically connected to the microgrid MG performs current control through a power conversion circuit (including an inverter). The master device operates via voltage control. Voltage control can be Constant Voltage Constant Frequency (CVCF) control. Since the independent operating unit 117 controls the master device, a constant voltage and constant frequency AC power is supplied from the master device, thus determining the frequency and voltage of the microgrid MG. Each slave device operates via current control based on the frequency and voltage determined by the master device. Hereinafter, the DER determined as the master device in the master plan will also be referred to as the "first master DER".

[0071] Independent operating unit 117 outputs adjustment commands to each DER. Adjustment commands sent to the DER (first master DER) intended to be used as a master device include, for example, information indicating that the DER (first master DER) should be used as a master device, and information indicating a target frequency and target voltage value. Adjustment commands sent to the DER intended to be used as a slave device include, for example, information indicating that the DER should be used as a slave device. Adjustment commands sent to the DER intended to be used as a slave device may include information indicating a target frequency and target voltage value.

[0072] The primary DER may stop (go offline) for various reasons. For example, the primary DER may go offline due to a disaster. In this case, the frequency in the microgrid MG cannot be determined, and independent operation cannot be properly performed.

[0073] Therefore, in this embodiment, when the first master DER fails, the independent operation unit 117 determines a new master device and performs (continues) master-slave control. In this embodiment, the independent operation unit 117 selects the master device from the energy storage type DERs based on information about the amount of power included in the resource information. More specifically, the independent operation unit 117 selects the DER with the highest remaining capacity from the energy storage type DERs included in the DER group 500 as the master device.

[0074] In BEV 11, the remaining capacity is the value of the remaining capacity of battery B1. In ESS 60, the remaining capacity is the value of the remaining capacity of the battery. FCEV 12 can also be included in the main unit candidates as a storage-type DER. In FCEV 12, the remaining capacity is the value of the remaining capacity of battery B2. In FCEV 12, the remaining capacity of battery B2 and the amount of power supplied from generator H2 to battery B2 can be reflected in the remaining capacity.

[0075] Independent operation unit 117 compares the remaining capacity of the energy storage type DERs and selects the DER with the highest remaining capacity as the master device. When a master device is selected, independent operation unit 117 performs voltage control on the selected master DER, determines a DER other than the master device as a slave device, and performs current control. The DER selected as the master DER by comparing remaining capacity will be referred to as the "second master DER". Therefore, even if the first master DER (the DER determined in the master plan) fails, the second master DER is determined as the master device to replace the first master DER and master-slave control is performed, allowing the independent operation of the microgrid MG to be properly performed (continued). When the DER with the highest remaining capacity is selected as the second master DER from the energy storage type DERs included in DER group 500, master-slave control with the selected DER as the master device can be performed for a longer period of time compared to selecting a lower capacity DER as the master device.

[0076] In master-slave control, the independent operating unit 117 can use the value obtained by dividing the total target current value by the number of slave devices as the target current value for each slave device. In other words, the target current value for each slave device is set to the same value. Alternatively, the target current value in the current control of the slave devices can be set according to the remaining capacity of each slave device. For example, the target current value of the slave device with higher remaining capacity can be set to be greater than the target current value of the slave device with lower remaining capacity. Alternatively, the target current value in the current control of the slave devices can be set according to the SOC of each slave device. For example, the target current value of the slave device with higher SOC can be set to be greater than the target current value of the slave device with lower SOC.

[0077] Furthermore, in this embodiment, when the remaining capacity of the second primary DER decreases during independent operation of the microgrid MG, the independent operation unit 117 changes the second primary DER. As a storage-type DER, the second primary DER may not be able to continue operating if its capacity decreases to a predetermined value. Therefore, the independent operation unit 117 monitors the remaining capacity of the second primary DER during independent operation, and when the remaining capacity of the second primary DER is lower than a threshold capacity, it changes the second primary DER to another DER. The threshold capacity is a threshold used to determine whether the DER selected as the second primary DER can continue operating. Specifically, when the remaining capacity of the second primary DER drops below the threshold capacity, the independent operation unit 117 selects the storage-type DER with the highest remaining power among the slave devices as the second primary DER. At this time, the independent operation unit 117 changes the DER that has been selected as the second primary DER (whose remaining capacity has decreased below the threshold capacity) to a slave device. Therefore, even when the remaining capacity of the second primary DER decreases, the independent operation of the microgrid MG can continue appropriately.

[0078] The amount of power required to continue operating varies depending on the DER. For example, a threshold capacity can be set for each DER based on the amount of power required to continue operating.

[0079] <Processing via CEMS server>

[0080] <<Processing during interconnection operation>>

[0081] Figure 3 This is a flowchart illustrating the process performed by the CEMS server 100 during the interconnection operation of the microgrid MG. During the interconnection operation of the microgrid MG, the CEMS server 100 repeatedly performs the following for each predetermined control cycle: Figure 3 The flowchart shown illustrates the processing. Although the description will focus on the case where each step is implemented via software processing by the CEMS server 100, it will be described below. Figure 3 and Figures 4 to 7 Each step in the flowchart shown (the following steps will be abbreviated as "S") can be implemented by some or all of the steps using hardware (electronic circuitry) manufactured in the CEMS server 100.

[0082] At S1, the CEMS server 100 determines, for example, whether a fault such as a power outage has occurred in the power grid PG (external network), i.e., whether the power supply from the power grid PG has been unintentionally stopped. If no fault has occurred in the power grid PG (under normal circumstances) (No at S1), the CEMS server 100 proceeds to S3 to continue interconnected operation. If a fault has occurred in the power grid PG (Yes at S1), the CEMS server 100 proceeds to S5 to switch from interconnected operation to stand-alone operation.

[0083] At S3, the CEMS server 100 operates the regulating force DER through current control to synchronize the power of the microgrid MG with the power of the grid PG. The CEMS server 100 adjusts the current of the microgrid MG through the regulating force DER (and accordingly, adjusts the supply and demand balance of the microgrid MG). When the processing in S3 is executed, the CEMS server 100 advances the processing to the return state.

[0084] In S5 to S9, because a fault has occurred in the power grid PG, the CEMS server 100 performs the process of switching from interconnected operation to stand-alone operation.

[0085] At point S5, the CEMS server 100 controls the circuit breaker of the power receiving and conversion facility 501 to disconnect it from the microgrid MG. As a result, the microgrid MG is separated from the power grid PG.

[0086] At S7, CEMS server 100 reads the master plan from memory 120 in order to switch from interconnected operation to standalone operation.

[0087] At S9, CEMS server 100 determines the DER (first master DER) to be used as the master DER based on the master plan read at S7. CEMS server 100 then identifies the DERs other than the first master DER as slave devices. CEMS server 100 then switches the control of DER group 500 from current control used for synchronization with the power grid PG to master-slave control. When the processing of S9 is executed, Figure 3 The series of processes shown here concludes, and the process described below begins. Figure 4 The processing shown.

[0088] <<Processing during stand-alone operation>>

[0089] Figure 4 This is a flowchart illustrating the process performed by the CEMS server 100 during the independent operation of the microgrid MG. Figure 4 The process shown in the flowchart is repeatedly executed by the CEMS server 100 for each predetermined control cycle during the independent operation of the microgrid MG.

[0090] At step S21, the CEMS server 100 determines whether the power grid PG (external network) that experienced a failure has been restored. If the power grid PG has not yet been restored (No at S21), the CEMS server 100 proceeds to step S23. If the power grid PG has been restored (Yes at S21), the CEMS server 100 proceeds to step S33.

[0091] At S23, CEMS server 100 determines whether the first primary DER has crashed. If the first primary DER is not crashed (No at S23), CEMS server 100 proceeds to S25. If the first primary DER has crashed (Yes at S23), CEMS server 100 proceeds to S27.

[0092] At S25, the CEMS server 100 continues master-slave control with the first master DER acting as the master device. The CEMS server 100 sends adjustment commands to each of the master and slave devices, thereby controlling them to stabilize the power of the microgrid MG. For example, the master device is operated via CVCF control. Each slave device operates through current control based on the frequency and voltage determined by the master device. Upon execution of the processing in S25, the CEMS server 100 advances the processing to a return state.

[0093] At S27, CEMS server 100 compares the remaining capacity of the battery-powered DER configured as a slave device to select the master device to replace the first master DER. CEMS server 100 may refer to memory 120 ( Figure 2 The remaining capacity of each energy storage DER can be obtained from the resource information in the database.

[0094] At step S29, the CEMS server 100 selects the DER with the highest remaining capacity from the energy-storage DERs configured as slave devices as the master device, and designates this DER as the second master DER. The CEMS server 100 designates all DERs other than the second master DER as slave devices.

[0095] At S31, CEMS server 100 performs master-slave control with the second master DER as the master device. (See reference...) Figure 5 The processing of S31 is described in detail. The processing of S27 and S29 is executed once, or not at each switch from interconnected operation to independent operation. In other words, during continuous independent operation, the processing of S27 and S29 will be skipped a second and subsequent times.

[0096] Figure 5 It is shown Figure 4 The detailed processing flowchart of S31.

[0097] At S311, CEMS server 100 determines whether the remaining capacity of the second primary DER has fallen below a threshold capacity. If it is determined that the remaining capacity of the second primary DER has fallen below the threshold capacity (Yes at S311), CEMS server 100 proceeds to S313. If it is determined that the remaining capacity of the second primary DER has not fallen below the threshold capacity (No at S311), CEMS server 100 proceeds to S317.

[0098] At S313, the CEMS server 100 compares the remaining capacity of the battery-type DER set as a slave device. The CEMS server 100 may refer to the memory 120 ( Figure 2 The remaining capacity of each energy storage DER can be obtained from the resource information in the database.

[0099] At step S315, the CEMS server 100 selects the DER with the highest capacity among the energy-saving DERs configured as slave devices as the master device, and determines this DER as the second master DER, replacing the DER currently configured as the second master DER. The CEMS server 100 also determines the DREs other than the second master DER as slave devices. The CEMS server 100 also determines the DERs that have been configured as the second master DER as slave devices.

[0100] At S317, the CEMS server 100 performs master-slave control. The CEMS server 100 sends adjustment commands to each of the master and slave devices, thereby controlling the master and slave devices to stabilize the power of the microgrid MG. For example, the master device is operated via CVCF control. Each slave device operates through current control based on the frequency and voltage determined by the master device. When the processing at S317 is executed, the processing returns to... Figure 4 S31, and the processing continues until the return.

[0101] Refer again Figure 4 At step S33, the CEMS server 100 switches the microgrid MG from stand-alone operation to interconnected operation. More specifically, the CEMS server 100 closes the circuit breaker (interconnection circuit breaker) of the power receiving and conversion facility 501 to connect the microgrid MG to the power grid PG. The CEMS server 100 also switches the power control mode of the microgrid MG from master-slave control to current control for synchronization with the power grid PG. When the processing in step S33 is executed, Figure 4 The series of processes shown in the diagram concludes. Then, when the microgrid MG begins interconnection operation, the aforementioned process begins. Figure 3 The processing.

[0102] In this embodiment, as described above, when the master device (first master DER) determined in the master plan fails during the independent operation of the microgrid MG, the CEMS server 100 selects a master device (selects a second master DER) from the energy storage type DERs included in the DER group 500 and executes master-slave control. Therefore, even when the first master DER fails, a new master device can be set, and master-slave control can be executed or continued. In other words, even when the first master DER fails, the independent operation of the microgrid MG can be appropriately executed or continued.

[0103] Among the energy-saving DERs included in DER group 500, the DER with the highest remaining capacity is selected as the second master DER. Because the DER with the highest remaining capacity is selected as the second master DER, master-slave control with the selected DER as the master DER can be performed for a longer period of time compared to when the DER with the lower remaining capacity is selected as the second master DER.

[0104] In master-slave control, when the remaining capacity of the second master DER drops below a threshold capacity, the CEMS server 100 selects the DER with the highest remaining capacity from the energy storage type DERs included in the DER group 500 as the new second master DER. Therefore, the independent operation of the microgrid MG can continue appropriately without stopping its independent operation.

[0105] [Variation Example 1]

[0106] In this embodiment, the remaining capacity of the energy-storage DER is used when selecting the second master DER in the master-slave control. Alternatively, any other parameter can be used when selecting the second master DER. For example, the second master DER in the master-slave control can be selected based on the SOC of the energy-storage DER.

[0107] During the independent operation of the microgrid MG, when the first master DER fails, the CEMS server 100 selects a second master DER to replace it. At this time, the CEMS server 100 selects the DER with the highest SOC among the energy storage DERs as the master device and designates it as the second master DER. The CEMS server 100 then designates the other DERs in the DER group 500 as slave devices. The CEMS server 100 then performs master-slave control.

[0108] During master-slave control, the CEMS server 100 monitors the State of Charge (SOC) of the second master DER. When the SOC of the second master DER drops to a threshold SOC, the CEMS server 100 changes the second master DER to any other DER. The threshold SOC is a threshold used to determine whether the DER selected as the second master DER can continue to operate. Specifically, when the SOC of the second master DER drops below the threshold SOC, the independent operation unit 117 of the CEMS server 100 selects the energy storage type DER with the highest SOC among the slave devices as the second master DER. At this time, the independent operation unit 117 changes the DER that has already been selected as the second master DER (whose SOC has dropped below the threshold SOC) to a slave device. Therefore, even when the SOC of the second master DER decreases, the independent operation of the microgrid MG can continue appropriately.

[0109] The amount of power required to continue operation can vary depending on the DER. A threshold SOC can be set for each DER based on the amount of power required to continue operation.

[0110] Figure 6 This is a flowchart illustrating the process performed by the CEMS server 100 during the independent operation of the microgrid MG in Modification 1. During the independent operation of the microgrid MG, the CEMS server 100 repeatedly performs the following for each predetermined control cycle. Figure 6 The flowchart shown illustrates the processing.

[0111] Figure 6 The flowchart is replaced by processing S51, S53, and S55 respectively. Figure 4 The flowchart is obtained by processing S27, S29 and S31. Figure 6 Any other processing of the flowchart and Figure 4 The processing of the flowcharts is similar, therefore, they are represented by the same step numbers and will not be described again.

[0112] At S23, when it is determined that the first primary DER has crashed (as stated in S23), the CEMS server 100 will advance the processing to S51.

[0113] At S51, the CEMS server 100 compares the SOC of the battery-powered DER configured as a slave device in order to select a master device to replace the first master DER. The CEMS server 100 may refer to the memory 120 ( Figure 2 The SOC of each energy storage DER is obtained from the resource information in the database.

[0114] At step S53, the CEMS server 100 selects the DER with the highest SOC from the battery-powered DERs configured as slave devices and designates this DER as the second master DER. The CEMS server 100 then designates all DERs other than the second master DER as slave devices.

[0115] At S55, CEMS server 100 performs master-slave control with the second master DER as the master device. (See reference...) Figure 7 The processing of S55 is described in detail. The processing of S51 and S53 is executed once, or not at each switch from interconnected operation to independent operation. In other words, during continuous independent operation, the processing of S51 and S53 will be skipped a second and subsequent times.

[0116] Figure 7 It is shown Figure 6 The detailed processing flowchart of S55.

[0117] At S551, CEMS server 100 determines whether the SOC of the second primary DER has dropped below the threshold SOC. If it is determined that the SOC of the second primary DER has dropped below the threshold SOC (Yes at S551), CEMS server 100 proceeds to S553. If it is determined that the SOC of the second primary DER has not dropped below the threshold SOC (No at S551), CEMS server 100 proceeds to S557.

[0118] At S553, the CEMS server 100 is compared to the SOC of the battery-powered DER of the slave device. The CEMS server 100 may refer to the memory 120 ( Figure 2 The SOC of each energy storage DER is obtained from the resource information in the database.

[0119] At S555, the CEMS server 100 selects the DER with the highest SOC among the battery-powered DERs configured as slave devices as the master device, and designates this DER as the second master DER, replacing the DER currently configured as the second master DER. The CEMS server 100 designates all DERs other than the second master DER as slave devices. The CEMS server 100 also designates DERs that have already been configured as the second master DER as slave devices.

[0120] At S557, CEMS server 100 performs master-slave control. When processing S557 is executed, the process returns to... Figure 6 The S55 process continues until the return.

[0121] In Variation 1, as described above, when the master device (first master DER) determined in the master plan fails during the independent operation of the microgrid MG, the CEMS server 100 selects a master device from the energy storage type DERs (selects a second master DER) and performs master-slave control. The DER with the highest SOC is selected from the energy storage type DERs included in the DER group 500 as the second master DER. As a result, even when the first master DER fails as in the embodiment, a new master device can be set, and master-slave control can be performed or continued. In other words, even when the first master DER fails, the independent operation of the microgrid MG can be appropriately started or continued.

[0122] This includes selecting the DER with the highest SOC among the energy storage DERs in DER group 500 as the second master DER. Because the DER with the highest SOC is selected as the second master DER, master-slave control with the selected DER as the master DER can be performed for a longer period of time compared to when the DER with the lower SOC is selected as the second master DER.

[0123] In master-slave control, when the SOC of the second master DER drops below a certain threshold SOC, the CEMS server 100 selects the DER with the highest SOC from the energy storage DERs included in the DER group 500 as the new second master DER. Therefore, the independent operation of the microgrid MG can continue appropriately without stopping its independent operation.

[0124] [Variation Example 2]

[0125] In Embodiment 1 and Modification 1, a second primary DER is selected from the energy storage type DERs included in DER group 500. Alternatively, a second primary DER can be selected from both the energy storage type DERs and the power generation type DERs included in DER group 500.

[0126] CEMS server 100 selects a second primary DER based, for example, on the amount of available power. Specifically, CEMS server 100 selects the DER with the largest amount of available power from among the energy storage DERs and power generation DERs included in DER group 500 as the second primary DER.

[0127] For example, in BEV 11, the amount of available power is the remaining capacity of battery B1. In ESS 60, the amount of available power is the value of the remaining battery capacity. In FCEV 12, the amount of available power is the value of the power that generator H2 can generate and the remaining capacity of battery B2. For example, the amount of power that generator H2 can generate can be calculated based on the remaining hydrogen in generator H2 and the power generation efficiency of generator H2. In FCS 70, the amount of available power is the value of the power that FCS 70 can generate. For example, the amount of power that FCS 70 can generate can be calculated based on the remaining hydrogen in hydrogen tank 71 and the power generation efficiency of FCS 70.

[0128] During the independent operation of the microgrid MG, when the first master DER fails, the CEMS server 100 selects a second master DER to replace it. At this time, the CEMS server 100 selects the DER with the largest available power from among the energy storage and generation DERs as the master DER and designates that DER as the second master DER. The CEMS server 100 then designates the other DERs in the DER group 500 as slave devices. The CEMS server 100 then executes master-slave control.

[0129] During master-slave control, the CEMS server 100 also monitors the amount of available power of the second master DER. When the amount of available power of the second master DER drops to a threshold power level, the CEMS server 100 changes the second master DER to any other DER. The threshold power level is a threshold used to determine whether the DER selected as the second master DER can continue to operate. Specifically, when the amount of available power of the second master DER drops below the threshold power level, the independent operation unit 117 of the CEMS server 100 selects the energy storage type DER or power generation type DER with the largest amount of available power among the slave devices as the second master DER. At this time, the independent operation unit 117 changes the DER that has already been selected as the second master DER (whose available power level has dropped below the threshold power level) to a slave device. Therefore, even when the amount of available power of the second master DER decreases, the independent operation of the microgrid MG can continue appropriately.

[0130] The amount of power required to continue operating can vary depending on the DER. A threshold power amount can be set for each DER based on the amount of power required to continue operating.

[0131] As described above, even by using a configuration that selects a second main DER from the energy storage type DER and the power generation type DER included in the DER group 500, similar effects to those in Embodiment 1 and Modification 1 can be achieved.

[0132] [Variation Example 3]

[0133] The power control of a microgrid MG has been described in Examples and Variations 1 and 2. However, in addition to the power control of a microgrid MG, this disclosure can also be used for the power control of a FEMS and a BEMS.

[0134] For example, when this disclosure is used for power control of a FEMS, it is sufficient to include the functionality of the CEMS server 100 described in the embodiments within the FEMS server. Then, the energy storage type DERs (e.g., BEV 11 and FCEV 12) included in the FEMS can be selected as the second primary DER. When this disclosure is used for power control of a BEMS, it is sufficient to include the functionality of the CEMS server 100 described in the embodiments within the BEMS server. Then, the energy storage type DERs (e.g., BEV 11 and FCEV 12) included in the BEMS can be selected as the second primary DER.

[0135] Although this disclosure has been described and illustrated in detail, it is clearly understood that this disclosure is by way of illustration and example only and should not be construed as limiting, and the scope of this disclosure is interpreted by the terms of the appended claims.

Claims

1. Power systems, including: Multiple power adjustment resources are electrically connected to the primary power grid; and Management equipment that manages the power of the first power grid, wherein, The first power grid is configured to connect to and disconnect from the second power grid. When the first power grid is connected to the second power grid and performs an interconnection with the second power grid, the management device performs current control of the plurality of power adjustment resources to synchronize with the frequency of the second power grid. When the first power grid is disconnected from the second power grid and operates independently, the management device designates predetermined power adjustment resources as master devices and power adjustment resources other than the predetermined power adjustment resources as slave devices. It then performs master-slave control of the plurality of power adjustment resources, and performs voltage control of the master device and current control of the slave devices. The predetermined power adjustment resources are those pre-determined from among the plurality of power adjustment resources. When the predetermined power adjustment resources are unavailable during the independent operation of the first power grid, the management device determines the master device from the plurality of power adjustment resources based on the power quantity information of the plurality of power adjustment resources, determines the power adjustment resources other than the determined master device as slave devices, and executes master-slave control of the plurality of power adjustment resources. The information regarding the amount of electricity refers to information indicating the current energy storage capacity. In the master-slave control, the management device identifies the power adjustment resource with the highest storage capacity among the plurality of power adjustment resources as the master device, and identifies the power adjustment resources other than the identified master device as slave devices. The plurality of power regulation resources include fuel cell electric vehicles, which include a battery and a generator having a fuel cell, and the energy storage capacity of the fuel cell electric vehicle includes the energy storage capacity of the battery and the amount of power supplied from the generator to the battery. In the master-slave control, when the energy storage capacity of the master device drops below a threshold capacity, the management device will identify the slave device with the highest energy storage capacity among the slave devices as the new master device, and will identify the power adjustment resources that have been used as the master device as slave devices.

2. A server that manages the power of a first power grid connected to multiple power adjustment resources. The first power grid is configured to connect to and disconnect from the second power grid. The server includes: A memory that stores information about the amount of electricity in the plurality of power adjustment resources; as well as Controller, in which When the first power grid is connected to the second power grid and performs interconnection with the second power grid, the controller performs current control of the plurality of power adjustment resources to synchronize with the frequency of the second power grid. When the first power grid is disconnected from the second power grid and operates independently, the controller identifies predetermined power adjustment resources as master devices and identifies power adjustment resources other than the predetermined power adjustment resources as slave devices. It then performs master-slave control of the plurality of power adjustment resources, and performs voltage control of the master device and current control of the slave devices. The predetermined power adjustment resources are those pre-determined from among the plurality of power adjustment resources. When the predetermined power adjustment resources are unavailable during the independent operation of the first power grid, the controller determines the master device from the plurality of power adjustment resources based on the information about the amount of power, designates the power adjustment resources other than the determined master device as slave devices, and executes master-slave control of the plurality of power adjustment resources. The information regarding the amount of electricity refers to information indicating the current energy storage capacity. In the master-slave control, the management device identifies the power adjustment resource with the highest storage capacity among the plurality of power adjustment resources as the master device, and identifies the power adjustment resources other than the identified master device as slave devices. The plurality of power regulation resources include fuel cell electric vehicles, which include a battery and a generator having a fuel cell, and the energy storage capacity of the fuel cell electric vehicle includes the energy storage capacity of the battery and the amount of power supplied from the generator to the battery. In the master-slave control, when the energy storage capacity of the master device drops below a threshold capacity, the management device will identify the slave device with the highest energy storage capacity among the slave devices as the new master device, and will identify the power adjustment resources that have been used as the master device as slave devices.

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