Power systems, electronic devices, power control methods, and computer programs

Abstract

To provide a power system, an electronic device, a power control method, and a computer program.SOLUTION: A power system according to the present embodiment includes a power storage device electrically connected to a power system, and a control unit that controls the power storage device on the basis of a power command from a higher-level control system that controls the input / output power of the power storage device, and transitions to an autonomous mode in which the input / output power of the power storage device is controlled on the basis of the remaining charge of the power storage device when at least one of the following conditions is satisfied: when it is detected that communication with the higher-level control system is interrupted; and when it is detected that connection between the power storage device and the power system is interrupted.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a power system, an electronic device, a power control method, and a computer program.

Background Art

[0002] A sub-system (microgrid) connected to a power system controls the value of the power output (discharge) from or input (charge) to a storage battery in the microgrid according to a command from a higher-level control system that maintains the power supply-demand balance within the microgrid.

[0003] Due to some cause, a communication failure may occur between the higher-level control system and the microgrid, and / or the electrical connection to the power system may be interrupted. In such a case, the microgrid needs to control the storage battery by itself without depending on the higher-level control system.

[0004] At this time, for example, if the storage battery continues to operate as per the command last received from the higher-level control system before the communication failure, it will eventually approach or reach a fully charged state (SoC = 100%) or a fully discharged state (SoC = 0%). If charging is further attempted in the fully charged state or discharging is further attempted in the fully discharged state, the storage battery may fail, so it is necessary to maintain the storage battery in a state that is not fully charged or fully discharged. Also, for example, even if the communication failure is resolved after the storage battery reaches the fully discharged state, the microgrid may not recover because there is insufficient power to operate the control device within the microgrid.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Embodiments of the present invention provide a power system, electronic device, power control method, and computer program that properly maintain the state of a storage battery even when communication with a higher-level control system is interrupted or when the power connection with a power grid is interrupted. [Means for solving the problem]

[0007] The power system according to this embodiment includes a power storage device electrically connected to a power grid, and a control unit that controls the power storage device based on power commands from a higher-level control system that controls the input and output power of the power storage device, and when it detects that communication with the higher-level control system has been interrupted, or when it detects that the connection between the power storage device and the power grid has been interrupted, it switches to an autonomous mode in which it controls the input and output power of the power storage device based on the remaining charge of the power storage device. [Brief explanation of the drawing]

[0008] [Figure 1] A block diagram showing a power system according to one embodiment. [Figure 2] A diagram illustrating an example of the controlled behavior of a battery SoC during charging. [Figure 3] A diagram illustrating an example of the behavior of a controlled battery SoC during discharge. [Figure 4] A flowchart illustrating an example of the operation performed by an inverter. [Figure 5] A diagram showing an example of the droop characteristics of a microgrid. [Figure 6] A diagram illustrating another example of the behavior of a controlled battery SoC during charging. [Figure 7] A diagram illustrating yet another example of the controlled SoC behavior of a battery during charging. [Figure 8] A diagram illustrating another example of the behavior of a controlled battery SoC during discharge. [Figure 9] A diagram illustrating yet another example of the behavior of a controlled battery SoC during discharge. [Figure 10] A block diagram showing an example of the hardware configuration in one embodiment of the present invention. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings.

[0010] (One embodiment) Figure 1 is a block diagram showing an example of an overall view of power system 1 according to one embodiment of the present invention. Thick lines represent power connections, and thin lines represent communication connections.

[0011] Power system 2 is a system for distributing electricity to consumer equipment 23. Power system 2 is connected to the microgrid 2M via a switch 22. Power system 2 can be of any size and type.

[0012] The portion of power system 2 to which inverter 21, synchronous generator 241, and consumer equipment 23 are connected is the microgrid 2M. In other words, the microgrid 2M is part of power system 2.

[0013] The microgrid 2M receives commands from the higher-level control system 3 and controls the power of the microgrid 2M itself based on these commands. The commands include, for example, a power command value P that specifies the power value (power value P) to be input to or output from the battery 214. command The command may also include frequency command values, voltage command values, etc. Hereinafter, the power value P and power command value P command This assumes active power values, but may also include reactive power values.

[0014] The upper control system 3 has a plurality of hierarchical structures. For example, it includes a central power supply command center 31 and an EMS (Energy Management System) 32. The central power supply command center 31 is the highest-level control system. The EMS 32 receives commands from the central power supply command center 31 and controls the inverter 21 via the communication unit 212. An EMS further below the EMS 32 may be provided within the microgrid 2M.

[0015] The switch 22 is opened (turned off) when an abnormality such as an accident occurs in the power system 2 or during work, interrupting the power transmission between the power system 2 and the inverter 21. During normal operation, for example, when there is no abnormality in the power system 2, the switch 22 is closed (turned on).

[0016] The customer device 23 is a load device that consumes power in homes, schools, factories, businesses, etc. The customer device 23 may include a power storage device that stores surplus power in the power system 2. There may be multiple customer devices 23.

[0017] The generator 24 supplies power to the power system 2 or the microgrid 2M. The generator 24 includes a synchronous generator 241 and / or a renewable energy generator 242.

[0018] The synchronous generator 241 generates AC power. There may be multiple synchronous generators 241. The synchronous generator 241 includes an emergency generator and / or a regular generator. The emergency generator is, for example, an emergency diesel generator.

[0019] The emergency generator is not operating during normal times, but when the microgrid 2M is disconnected from the power system 2, it starts operating upon instruction from an operator. The operator may give the instruction via a switch such as a button provided on the synchronous generator 241, or may give the instruction wirelessly or wired from a terminal available to the operator.

[0020] The renewable energy generator 242 generates variable renewable energy. The renewable energy generator 242 is, for example, a solar power generator. If the renewable energy generator 242 is a solar power generator, it may be equipped with a converter that converts the output power from DC power to AC power.

[0021] The inverter 21 is an electronic device for supplying power stored in the battery 214 to the consumer equipment 23. The power output from the inverter 21 is converted to an appropriate voltage by, for example, transformers 25a and 25c and supplied to the consumer equipment 23. Alternatively, the power output from the inverter 21 may be transmitted to the power grid 2 via transformers 25a and 25b (reverse power flow). The inverter 21 is also called a power converter or PCS (Power Conditioning System).

[0022] The inverter 21 is connected to the microgrid 2M via the transformer 25a. The inverter 21 functions as either a current-controlled inverter (Grid following inverter) that controls the current output to the microgrid 2M from the power supplied by the battery, or a voltage-controlled inverter (Grid forming inverter) that controls the voltage output to the microgrid 2M. The inverter 21 may be switched between being a voltage-controlled inverter or a current-controlled inverter by the control unit 211.

[0023] The inverter 21 comprises a control unit 211, a communication unit 212, an input / output unit 213, a storage battery (energy storage device) 214, a DC / DC converter 215, a DC / AC inverter 216, a current sensor 217, a voltage sensor 218, and a renewable energy generator 219.

[0024] At least some of elements 211 to 219 may consist of circuits or processors such as microcontrollers, ASICs (application-specific integrated circuits), or FPGAs (field-programmable gate arrays). Alternatively, some or all of these elements may be executed by a CPU that executes a program.

[0025] The control unit 211 controls the inverter 21. The operation of the control unit 211 will be explained in detail in the operation example described later.

[0026] The communication unit 212 is connected to the EMS 32 of the higher-level control system 3 via a communication network, and communicates between the higher-level control system 3 and the control unit 211. The communication network may be a wireless communication network such as a wireless LAN, mobile network, or Bluetooth, or a wired communication network such as a dedicated line, Ethernet, or serial communication cable. The communication unit 212 may also communicate directly with the central power dispatch center 31 without going through the EMS 32.

[0027] The input / output unit 213 receives instructions from the user (worker). These instructions may include, for example, an instruction to deactivate the autonomous mode, as described later. The input / output unit 213 also outputs information indicating the status of each element of the inverter 21, such as the SoC value of the battery 214.

[0028] The battery 214 is a rechargeable secondary battery that stores the power consumed by the consumer equipment 23 and the control unit 211. For the purposes of this explanation, the sign of the power value P input and output by the battery 214 will be "+" for the discharge direction (power output) and "-" for the charging direction (power input). The discharge direction of the battery 214 is the direction in which power is output from the inverter 21 to the microgrid 2M. The charging direction of the battery 214 is the direction in which power is input from the microgrid 2M to the inverter 21. Note that the definitions of positive and negative may be reversed.

[0029] The DC / DC converter 215 converts the DC voltage of the DC power supplied from the battery 214 to a DC-DC converter. The DC / AC inverter 216 converts the DC power supplied from the battery 214, which has been DC-DC converted by the DC / DC converter 215, into AC power that can be used by the customer equipment 23.

[0030] The current sensor 217 detects the current of the microgrid 2M (the current at the output terminal of the inverter 21) and outputs information indicating the detected current to the control unit 211. The voltage sensor 218 detects the voltage of the microgrid 2M (the voltage at the output terminal of the inverter 21) and outputs information indicating the detected voltage to the control unit 211.

[0031] The renewable energy generator 219 is a power supply device that generates electricity to be consumed by the consumer equipment 23 and the control unit 211. The renewable energy generator 219 may also supply power to the storage battery 214. The renewable energy generator 219 generates variable renewable energy. The renewable energy generator 219 is, for example, a solar power generator.

[0032] (Example of operation of the control unit 211) The operation of the control unit 211 will be described below with reference to the drawings. In a normal state, the control unit 211 receives commands from the higher-level control system 3 (power command value P command The power value P of the storage battery 214 is controlled according to the specified parameters. Here, "normal state" refers to a state in which communication between the higher-level control system 3 and the communication unit 212 is maintained and the switch 22 is closed.

[0033] On the other hand, in an emergency situation, the control unit 211 switches to an "autonomous mode" in which it independently controls the power value P of the battery 214 based on the remaining charge of the battery 214. In this embodiment, SoC is used as the remaining charge, but other values ​​or indicators such as the amount of charge stored in the battery 214 may also be used. Here, "emergency situation" refers to a state that satisfies at least one of the following conditions: when the control unit 211 determines that communication between the higher-level control system 3 and the communication unit 212 is interrupted (a communication failure has occurred), and when the switch 22 is open.

[0034] A communication failure occurs if at least one of the following is not functioning correctly: the higher-level control system 3, the communication unit 212, or the communication network between the higher-level control system 3 and the communication unit 212. For example, if the higher-level control system 3 periodically sends signals to the communication unit 212, and the communication unit 212 fails to receive these periodic signals, the control unit 211 determines that a communication failure has occurred. Alternatively, if the communication unit 212 periodically sends echo requests to the higher-level control system 3 for communication confirmation, and fails to receive a response such as an ACK (ACKnowledgement) signal from the higher-level control system within a specified time, the control unit 211 determines that a communication failure has occurred.

[0035] Furthermore, as previously mentioned, if an abnormality such as an accident occurs in power system 2, or during maintenance work, switchgear 22 will be opened. When switchgear 22 is open, the microgrid 2M is electrically isolated (shut off) from power system 2.

[0036] In any case, when the control unit 211 detects an emergency situation, it switches to autonomous mode. After switching to autonomous mode, the control unit 211 controls the inverter 21 until the power system 1 returns to a normal state. Alternatively, if there is an effective control method other than control by the control unit 211, the user may manually exit autonomous mode via the input / output unit 213.

[0037] If the switch 22 is closed, the control unit 211 may determine that the power system 1 has been restored when communication between the higher-level control system 3 and the communication unit 212 is resumed, and then cancel the autonomous mode. Alternatively, if the switch 22 is closed, the control unit 211 may determine that the power system 1 has been restored when the communication unit 212 receives a command from the higher-level control system 3, and then cancel the autonomous mode.

[0038] The operation of the control unit 211 in autonomous mode will be explained below with reference to the drawings. Power will be explained using the pu (per unit) method, which is standardized using the rated power of battery 214. Battery 214 has a capacity of 20kWh, a rated power (1pu) of 20kW, and a grid frequency of 50Hz. Hereafter, "SoC" will refer to the SoC of battery 214.

[0039] [When charging] First, under normal conditions, the power command value P is sent from the higher-level control system 3. command Assume that a command of -20kW (i.e., charging at 20kW per hour) is issued, and that battery 214 is being charged at a power value P = -20kW. Then, as shown in Figure 2, assume that the system transitioned to an emergency state when SoC = 50% (t = 0).

[0040] If nothing is done at this time, even if the system transitions to an emergency state, the battery 214 will continue to charge at 20kW per hour according to the normal state command from the higher-level control system 3, and will approach or reach SoC = 100% after 0.5 hours.

[0041] Therefore, as shown in Figure 2, when the SoC reaches a first threshold (for example, 85%) (t=T1), the control unit 211 controls the system to stop inputting power to the battery 214 (charging), that is, to make the power value P of the battery 214 0pu (0kW) (first operation).

[0042] Subsequently, the power value P of the battery 214 is 0pu, but the SoC gradually decreases due to standby power (t=T1~T2).

[0043] If the power input to the battery 214 is kept stopped (the power value P is kept at 0pu), the SoC will eventually approach or reach 0% due to standby power. Therefore, when the SoC reaches a second threshold (e.g., 80%) (t=T2), the control unit 211 charges the battery 214 (second operation). The second threshold is a lower value than the first threshold.

[0044] During charging, the battery 214 is charged with a certain power value P (t=T2~T3). For example, it may be charged with the power value P of the normal state (i.e., the same power value P as when t=0~T1), or it may be charged with any power value P. When the SoC reaches the first threshold again due to charging, the control unit 211 stops the power input (charging) to the battery 214 again, that is, it sets the power value P of the battery 214 back to 0 (0pu) (first operation).

[0045] As explained above, once the SoC reaches the first threshold, the first and second operations can be alternately repeated to keep the SoC value between the first and second thresholds, thereby preventing the SoC from approaching or reaching 100%.

[0046] [During discharge] Even during discharge, the same control as during charging is possible by appropriately setting the first and second thresholds. As shown in Figure 3, let's assume that during discharge, the system transitions to an emergency state when SoC = 50% (t = 0).

[0047] When the SoC reaches a first threshold (e.g., 20%) (t=T4), the control unit 211 controls the battery 214 to stop outputting power (discharging), that is, to make the power value P of the battery 214 0pu (first operation).

[0048] Subsequently, the power value P of the battery 214 is 0pu, but the SoC gradually decreases due to standby power (t=T4~T5).

[0049] Even if the power output of the battery 214 is continuously stopped, the SoC will eventually approach or reach 0% due to standby power. Therefore, when the SoC reaches a second threshold (e.g., 15%) (t=T5), the control unit 211 causes the battery 214 to charge (second operation).

[0050] During charging, the battery 214 is charged to an arbitrary power value P (t=T5~T6). When the SoC reaches the first threshold again due to charging, the control unit 211 stops the power output of the battery 214 again, that is, it sets the power value P of the battery 214 back to 0pu (first operation).

[0051] As explained above, even during discharge, once the SoC reaches the first threshold, the first and second operations are repeated alternately so that the SoC value falls between the first and second thresholds, preventing the SoC from approaching or reaching 0%.

[0052] In other words, in autonomous mode, when the SoC reaches a first threshold, whether during charging or discharging, the control unit 211 performs a first operation to stop the input and output of power to the battery 214. After the first operation, when the SoC decreases due to standby power and reaches a second threshold, the control unit 211 performs a second operation to charge the battery 214.

[0053] Furthermore, although the above explanation assumes that the power value P is controlled based on the SoC, the power value P may also be controlled based on the elapsed time after transitioning to autonomous mode. For example, during discharge, the first operation may be performed at t=T1, the second operation at t=T2, the first operation at t=T3, and so on, with the first and second operations being repeated alternately at predetermined time intervals (see Figure 2).

[0054] (flowchart) Figure 4 is a flowchart illustrating the operation of the inverter 21. First, the control unit 211 detects an emergency condition (step S1). Upon detecting an emergency condition, the control unit 211 switches to autonomous mode (step S2).

[0055] Next, the SoC of the battery 214 reaches the first threshold (step S3). When the control unit 211 detects that the SoC has reached the first threshold, it stops the power input and output of the battery 214 (step S4).

[0056] Next, the SoC of the battery 214 reaches a second threshold due to standby power (step S5). When the control unit 211 detects that the SoC has reached the second threshold, it starts charging the battery 214 (step S6). Then, the process returns to step S3.

[0057] Furthermore, after transitioning to autonomous mode, the control unit 211 continuously determines whether the system has returned to a normal state (step S7). Steps S3 to S6 are repeated until the control unit 211 determines that the system has returned to a normal state (step S7: No).

[0058] If the control unit 211 determines that the system has returned to a normal state at any point after transitioning to autonomous mode (step S7: Yes), it terminates (cancels) autonomous mode (step S8). After the autonomous mode is terminated, the battery 214 is controlled based on commands from the higher-level control system 3.

[0059] Furthermore, if the SoC has reached the first threshold at the time the control unit 211 transitions to autonomous mode (step S2), the control unit 211 may immediately stop the input and output of power to the battery 214. Also, if the battery 214 is discharging and the SoC is below the second threshold at the time the control unit 211 transitions to autonomous mode (step S2), the control unit 211 may immediately charge the battery 214.

[0060] As described above, by controlling the SoC of the battery 214 between two thresholds, it is possible to prevent the SoC from approaching or reaching 100% or 0%. Furthermore, by providing two thresholds, a first threshold and a second threshold, for switching the operation, and by giving the thresholds hysteresis, it is possible to simplify the control by not having to frequently switch the operation even if the SoC fluctuates due to noise, etc.

[0061] Furthermore, if the generator 24 and inverter 21 (storage battery 214 and inverter 216) within the microgrid 2M have droop characteristics (hanging characteristics), the SoC of the storage battery 214 may fluctuate independently of the control of the control unit 211 in an emergency situation. Here, we will explain the droop characteristics of the generator 24 and inverter 21 of the microgrid 2M. Figure 5 shows an example of the droop characteristics of the generator 24 and inverter 21 of the microgrid 2M. More specifically, it shows the droop characteristics of the governor (speed governor) of the synchronous generator 241 of the microgrid 2M and the behavior of the battery 214 associated with these droop characteristics.

[0062] Within the microgrid 2M, it is desirable to maintain a constant balance between power supply and demand. Therefore, the microgrid 2M can stabilize the power supply and demand balance by matching the frequency of the synchronous generator 241 (system frequency) to the reference frequency (e.g., 50Hz) as closely as possible. To this end, the generators 24 and inverters 21 of the microgrid 2M are given droop characteristics.

[0063] For example, under normal conditions, the power value P generated (supplied) by the synchronous generator 241 at the reference frequency (50Hz) is... supply Assume that a power generation command value of 1pu is issued from the higher-level control system 3 so that the value becomes =1pu.

[0064] If the power generation command value to the synchronous generator 241 is insufficient for the amount of power consumed (demand) within the microgrid 2M (power generation command value < demand), the grid frequency of the synchronous generator 241 will fall below 50 kHz due to the droop characteristic. As shown in Figure 5, when the grid frequency falls below 50 kHz, the battery 214 is controlled to discharge in order to compensate for the insufficient supply. On the other hand, if the power generation command value to the synchronous generator 241 is excessive relative to the amount of consumption (demand) (power generation command value > demand), the grid frequency of the synchronous generator 241 will exceed 50 kHz due to the droop characteristic. As shown in Figure 5, when the grid frequency exceeds 50 kHz, the battery 214 is controlled to charge in order to suppress the excessive supply. Then, when the power generation command value to the synchronous generator 241 is approximately the same as the amount of consumption (demand), the grid frequency of the synchronous generator 241 becomes 50 Hz due to the droop characteristic (power generation command value = demand). As shown in Figure 5, when the grid frequency is 50 kHz, the power generated by the synchronous generator 241 is consumed within the microgrid 2M without any surplus or deficit. Therefore, the battery 214 does not need to discharge or charge and is controlled to stop its input and output (so that the power value P = 0 pu).

[0065] As explained above, if the inverter 21 in the microgrid 2M has droop characteristics, it is adjusted to stabilize the power supply balance within the microgrid 2M. However, in an emergency situation, the droop characteristics may cause the battery 214 to approach or reach a fully charged or fully discharged state independently of the control unit 211. Therefore, at any given time, for example, when the SoC exceeds / falls below a predetermined threshold, i.e., when the SoC is not within a predetermined range, the control unit 211 may disable the governor droop characteristics of the inverter 21. Alternatively, when transitioning to autonomous mode, the control unit 211 may disable the governor droop characteristics of the inverter 21.

[0066] Alternatively, the synchronous generator 241 may have both an isochronous governor and a droop governor. When the synchronous generator 241 operates using the isochronous governor, the rotational speed of the synchronous generator 241 is controlled to remain constant regardless of the load (demand power) connected to the synchronous generator 241. Furthermore, if the SoC exceeds / falls above a predetermined threshold, or if the system transitions to autonomous mode, the control unit 211 may switch the governor of the synchronous generator 241 to the isochronous governor.

[0067] Similarly, when the inverter 21 includes a renewable energy generator 219 and / or the generator 24 includes a renewable energy generator 242, the renewable energy generator 219 and / or the renewable energy generator 242 may have a pseudo-inertial force. For example, when the power demand in the microgrid 2M changes, the control unit 211 controls the battery 214 to charge or discharge an amount of energy corresponding to the change in power demand, that is, it imparts a pseudo-inertial force to the output from the battery 214. The control unit 211 may also impart a pseudo-inertial force to the output from the renewable energy generator 219. This stabilizes the supply-demand balance in the microgrid 2M.

[0068] However, in an emergency situation, the pseudo-inertial force of the renewable energy generator 219 may cause the battery 214 to approach or reach a fully charged or completely discharged state independently of the control of the control unit 211. Therefore, the pseudo-inertial force of the renewable energy generator 219 may be disabled at any time (for example, when the SoC exceeds / falls below a predetermined threshold, or when the system switches to autonomous mode).

[0069] (Another example of operation) The power value P of the battery 214 may be gradually reduced, i.e., brought closer to 0pu, depending on the SoC of the battery 214 or the elapsed time since transitioning to autonomous mode, thereby stopping the input and output of the battery 214. This can avoid abrupt changes in the power balance within the microgrid 2M and reduce the burden on the microgrid 2M (especially the consumer equipment 23 and / or generator 24).

[0070] For example, as shown in Figure 6, the input power (charging power) may be gradually reduced, that is, the power value P may be gradually decreased. In the example shown in Figure 6, the power value P is controlled as follows (1) to (4). (1) Until the SoC reaches 80% or until t=T7, the power value P will be the previous value, i.e., the power command value P received under normal conditions. commandThe value (in this case, -20kW) is maintained. (2) When the SoC reaches 80% or t=T7, change the power value P from -20kW to -15kW. (3) When the SoC reaches 85% or t=T8, change the power value P to -10kW. (4) When the SoC reaches 90% or t=T9, change the power value P to -5kW. (5) When the SoC reaches 95%, or t=T 10 When this happens, change the power value P to 0kW.

[0071] Alternatively, as shown in Figure 7, the power value P of the battery 214 may be continuously reduced according to the SoC of the battery 214 or according to the elapsed time after transitioning to autonomous mode. In other words, the absolute value of the power value P may be reduced as the SoC size increases or as the elapsed time after transitioning to autonomous mode increases.

[0072] In any case, as described above, the input and output of the battery 214 are stopped by gradually or continuously reducing the power value P of the battery 214. After that, the first operation and the second operation may be repeated alternately between any first and second thresholds.

[0073] Similarly, during discharge, as shown in Figure 8 or Figure 9, the output power (discharge power) is reduced in stages or continuously, that is, the power value P is reduced in stages or continuously. In other words, the absolute value of the power value P may be reduced as the SoC becomes smaller or as the elapsed time after transitioning to autonomous mode increases. Thereafter, the first and second operations may be repeated alternately between any first and second thresholds.

[0074] As described above, by gradually reducing the power value P depending on the SoC or over time, the input and output of the battery 214 can be stopped, thereby avoiding abrupt changes in the power balance within the microgrid 2M.

[0075] As described above, according to this embodiment, in an emergency situation, it is possible to prevent the SoC of the storage battery 214 from approaching or reaching 0% or 100%. This prevents the storage battery 214 from failing. Furthermore, since the storage battery 214 is always charged with a certain amount of power, power for the operation of the control unit 211 is always secured, and it is possible to quickly restore to a normal state.

[0076] (Hardware configuration)

[0077] Figure 10 is a block diagram showing an example of the hardware configuration of a control unit 211 according to one embodiment of the present invention. The control unit 211 comprises a processor (arithmetic unit) 41, a main memory 42, an auxiliary memory 43, a network interface 44, and a device interface 45, which can be realized as a computer device 4 connected via a bus 46.

[0078] Although the computer device 4 in Figure 10 has one of each component, it may have multiple identical components. Also, although Figure 10 shows one computer device 4, the software may be installed on multiple computer devices, and each of these multiple computer devices may execute different parts of the software's processing.

[0079] The processor 41 performs calculations based on data and programs input from the internal configuration of the computer device 4, and outputs calculation results and control signals to each device. Specifically, the processor 41 executes the OS (operating system) and applications of the computer device 4, and controls each device that makes up the computer device 4. The processor 41 is not particularly limited as long as it can perform the above-mentioned processing. The main processing of the control unit 211 is performed by the processor 41.

[0080] The main memory 42 is a memory device that stores instructions executed by the processor 41 and various data, and the information stored in the main memory 42 is read directly by the processor 41. The auxiliary memory 43 is a memory device other than the main memory 42. At least one of the main memory 42 and the auxiliary memory 43 may be treated as the storage unit 47. If parameters such as how to change the droop characteristics, or functions that represent the droop characteristics, are prepared in advance, multiple such functions can be stored in the storage unit 47. These memory devices refer to any electronic component capable of storing electronic information, and may be either memory or storage. Furthermore, there are volatile memory and non-volatile memory, and either is acceptable.

[0081] The network interface 44 and the device interface 45 are included in the communication unit 48, which is a component for communicating with devices other than the computer device 4 (external devices 6A and 6B). At least one of the network interface 44 and the device interface 45 may be treated as the communication unit 212. Communication with the external devices 6A and 6B can be performed by the communication unit 48.

[0082] The network interface 44 is an interface for connecting to the communication network 5 wirelessly or via a wired connection. The network interface 44 may conform to existing communication standards. Information may be exchanged with an external device 6A connected via the communication network 5 through the network interface 44.

[0083] The device interface 45 is an interface such as USB that connects directly to the external device 6B. The external device 6B may be an external storage medium or a storage device such as a database.

[0084] External devices 6A and 6B may also be output devices. Output devices may be, for example, display devices for displaying images, or devices that output sound, etc. Examples include, but are not limited to, LCDs (Liquid Crystal Displays), CRTs (Cathode Ray Tubes), PDPs (Plasma Display Panels), and speakers.

[0085] External devices 6A and 6B may also be input devices. These input devices include keyboards, mice, touch panels, and other devices, and provide information input via these devices to the computer device 4. Signals from the input devices are output to the processor 41.

[0086] It should be noted that the present invention is not limited to the embodiments described above, and the components can be modified and implemented in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the embodiments described above. For example, a configuration in which some components are removed from all the components shown in each embodiment is also conceivable. Moreover, components described in different embodiments may be appropriately combined.

[0087] This embodiment can also be configured as follows. [Item 1] A power storage device electrically connected to the power grid, Based on power commands from a higher-level control system that controls the input and output power of the energy storage device, the energy storage device is controlled. A control unit, which detects that communication with the higher-level control system has been interrupted, and detects that the connection between the energy storage device and the power grid has been interrupted, switches to an autonomous mode in which it controls the input and output power of the energy storage device based on the remaining charge of the energy storage device, A power system equipped with this. [Item 2] In the autonomous mode, when the remaining charge reaches a first threshold, the control unit performs a first operation to stop the power input and output of the energy storage device. After the first operation, when the remaining charge reaches a second threshold due to standby power, a second operation is performed to charge the energy storage device. The power system described in item 1. [Item 3] The control unit, in the autonomous mode, stops the input and output of power to the energy storage device by gradually or continuously reducing the input power or output power of the energy storage device according to the remaining charge level of the energy storage device. The power system described in item 1 or 2. [Item 4] The control unit, during the autonomous mode, stops the input and output of power to the energy storage device by gradually or continuously reducing the input power or output power of the energy storage device according to the elapsed time of the autonomous mode. The power system described in item 1 or 2. [Item 5] The control unit and, An inverter that converts the DC power supplied from the aforementioned energy storage device into AC power, Further comprising an electronic device including, After transitioning to the autonomous mode, if the remaining charge of the energy storage device is not within a predetermined range, the droop characteristics of the electronic device are disabled. A power system as described in any of items 1-4. [Item 6] The control unit and, A power supply device that supplies power to the aforementioned energy storage device, Further comprising an electronic device including, The control unit applies a pseudo-inertial force to the output from the power supply device. When the system switches to the aforementioned autonomous mode, the aforementioned pseudo-inertial force is disabled. A power system as described in any of items 1-5. [Item 7] The control unit and, A communication unit that performs communication between the above-level control system and the control unit, Further comprising an electronic device including, The aforementioned electronic device periodically sends requests to the higher-level control system. If the electronic device fails to receive a response from the higher-level control system within a specified time, The control unit transitions to the autonomous mode. A power system as described in any of items 1-6. [Item 8] When the control unit determines that communication with the higher-level control system has resumed while the connection between the energy storage device and the power grid is secured, it cancels the autonomous mode. A power system as described in any of items 1-7. [Item 9] When the control unit maintains a connection between the energy storage device and the power grid, and communication with the higher-level control system resumes, and the control unit receives a command from the higher-level control system regarding the control of the energy storage device, it deactivates the autonomous mode. A power system as described in any of items 1-7. [Item 10] The remaining charge is SoC. A power system as described in any of items 1-9. [Item 11] Based on power commands from a higher-level control system that controls the input and output power of an energy storage device electrically connected to the power grid, the energy storage device is controlled. The control unit, upon detecting that communication with the higher-level control system has been interrupted, and upon detecting that the connection between the energy storage device and the power grid has been interrupted, switches to an autonomous mode in which it controls the input and output power of the energy storage device based on the remaining charge of the energy storage device. An electronic device equipped with [a specific feature / ability]. [Item 12] A step of controlling an energy storage device based on a power command from a higher-level control system that controls the input and output power of the energy storage device electrically connected to the power grid, If at least one of the following is detected—that communication with the higher-level control system has been interrupted, and that the connection between the energy storage device and the power grid has been interrupted—the system transitions to an autonomous mode in which the input and output power of the energy storage device is controlled based on the remaining charge of the energy storage device. A power control method equipped with a power control system. [Item 13] A step of controlling an energy storage device based on a power command from a higher-level control system that controls the input and output power of the energy storage device electrically connected to the power grid, If at least one of the following is detected—that communication with the higher-level control system has been interrupted, and that the connection between the energy storage device and the power grid has been interrupted—the system transitions to an autonomous mode in which the input and output power of the energy storage device is controlled based on the remaining charge of the energy storage device. A computer program that causes a computer to execute something. [Explanation of symbols]

[0088] 1. Power Systems 2 Power system 2M Microgrid 21 Inverter 211 Control Unit 212 Communications Department 213 Input / output section 214. Storage batteries (energy storage devices) 215 DC / DC Converter 216 DC / AC Inverter 217 Current Sensor 218 Voltage Sensor 219 Renewable energy generators 22 Switch 23 Consumer equipment 24 Generators 241 Synchronous Generator 242 Renewable Energy Generators 25a, 25b, 25c transformers 3. Higher-level control system 31 Central Power Dispatch Station 32 EMS 4. Computer equipment 41. Processor (Arithmetic Unit) 42 Main storage 43 Auxiliary storage device 44 Network Interfaces 45 device interfaces 46 bus 47 Memory section 48 Communications Department 5. Communication Network 6A, 6B External device

Claims

1. A power storage device electrically connected to the power grid, Based on power commands from a higher-level control system that controls the input and output power of the energy storage device, the energy storage device is controlled. A control unit, which detects that communication with the higher-level control system has been interrupted, and detects that the connection between the energy storage device and the power grid has been interrupted, switches to an autonomous mode in which it controls the input and output power of the energy storage device based on the remaining charge of the energy storage device, Equipped with, In the autonomous mode, when the remaining charge reaches a first threshold, the control unit performs a first operation to stop the power input and output of the energy storage device. After the first operation, when the remaining charge reaches a second threshold due to standby power, a second operation is performed to charge the energy storage device. When the remaining charge reaches the first threshold as a result of the second operation, the first operation is performed again. Power system.

2. A power storage device electrically connected to a power grid, Based on power commands from a higher-level control system that controls the input and output power of the energy storage device, the energy storage device is controlled. A control unit, which detects that communication with the higher-level control system has been interrupted, and detects that the connection between the energy storage device and the power grid has been interrupted, switches to an autonomous mode in which it controls the input and output power of the energy storage device based on the remaining charge of the energy storage device, Equipped with, The control unit, in the autonomous mode, stops the input and output of power to the energy storage device by gradually or continuously reducing the input power or output power of the energy storage device according to the remaining charge level of the energy storage device. Power system.

3. A power storage device electrically connected to a power grid, Based on power commands from a higher-level control system that controls the input and output power of the energy storage device, the energy storage device is controlled. A control unit, which detects that communication with the higher-level control system has been interrupted, and detects that the connection between the energy storage device and the power grid has been interrupted, switches to an autonomous mode in which it controls the input and output power of the energy storage device based on the remaining charge of the energy storage device, Equipped with, The control unit, during the autonomous mode, stops the input and output of power to the energy storage device by gradually or continuously reducing the input power or output power of the energy storage device according to the elapsed time of the autonomous mode. Power system.

4. A power storage device electrically connected to a power grid, Based on power commands from a higher-level control system that controls the input and output power of the energy storage device, the energy storage device is controlled. A control unit, which detects that communication with the higher-level control system has been interrupted, and detects that the connection between the energy storage device and the power grid has been interrupted, switches to an autonomous mode in which it controls the input and output power of the energy storage device based on the remaining charge of the energy storage device, Equipped with, The control unit and, An inverter that converts the DC power supplied from the aforementioned energy storage device into AC power, Further comprising an electronic device including, After transitioning to the autonomous mode, if the remaining charge of the energy storage device is not within a predetermined range, the droop characteristics of the electronic device are disabled. Power system.

5. A power storage device electrically connected to a power grid, Based on power commands from a higher-level control system that controls the input and output power of the energy storage device, the energy storage device is controlled. A control unit, which detects that communication with the higher-level control system has been interrupted, and detects that the connection between the energy storage device and the power grid has been interrupted, switches to an autonomous mode in which it controls the input and output power of the energy storage device based on the remaining charge of the energy storage device, Equipped with, The control unit and, A power supply device that supplies power to the aforementioned energy storage device, Further comprising an electronic device including, The control unit applies a pseudo-inertial force to the output from the power supply device. When the system switches to the aforementioned autonomous mode, the aforementioned pseudo-inertial force is disabled. Power system.

6. The control unit and, A communication unit that performs communication between the above-level control system and the control unit, Further comprising an electronic device including, The aforementioned electronic device periodically sends requests to the higher-level control system. If the electronic device fails to receive a response from the higher-level control system within a specified time, The control unit transitions to the autonomous mode. The power system according to claim 2.

7. When the control unit determines that communication with the higher-level control system has resumed while the connection between the energy storage device and the power grid is secured, it cancels the autonomous mode. The power system according to claim 2.

8. When the control unit maintains a connection between the energy storage device and the power grid, and communication with the higher-level control system resumes, and the control unit receives a command from the higher-level control system regarding the control of the energy storage device, it deactivates the autonomous mode. The power system according to claim 2.

9. The remaining charge is SoC. The power system according to any one of claims 1 to 8.

10. Based on power commands from a higher-level control system that controls the input and output power of an energy storage device electrically connected to the power grid, the energy storage device is controlled. The control unit, upon detecting that communication with the higher-level control system has been interrupted, and upon detecting that the connection between the energy storage device and the power grid has been interrupted, switches to an autonomous mode in which it controls the input and output power of the energy storage device based on the remaining charge of the energy storage device. Equipped with, The control unit, in the autonomous mode, stops the input and output of power to the energy storage device by gradually or continuously reducing the input power or output power of the energy storage device according to the remaining charge level of the energy storage device. electronic equipment.

11. A step of controlling an energy storage device based on a power command from a higher-level control system that controls the input and output power of the energy storage device electrically connected to the power grid, If it is detected that communication with the higher-level control system has been interrupted, and if at least one of the following is detected: that the connection between the energy storage device and the power grid has been interrupted, the system transitions to an autonomous mode in which the input and output power of the energy storage device is controlled based on the remaining charge of the energy storage device. Equipped with, The transition step involves stopping the input and output of power to the energy storage device by gradually or continuously reducing the input power or output power of the energy storage device in accordance with the remaining charge level of the energy storage device during the autonomous mode. Power control method.

12. A step of controlling an energy storage device based on a power command from a higher-level control system that controls the input and output power of the energy storage device electrically connected to the power grid, If it is detected that communication with the higher-level control system has been interrupted, and if at least one of the following is detected: that the connection between the energy storage device and the power grid has been interrupted, the system transitions to an autonomous mode in which the input and output power of the energy storage device is controlled based on the remaining charge of the energy storage device. Have the computer run it, The transition step involves stopping the input and output of power to the energy storage device by gradually or continuously reducing the input power or output power of the energy storage device in accordance with the remaining charge level of the energy storage device during the autonomous mode. Computer program.

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