JP7531340B2 - Battery control device and battery system - Google Patents

Description

This disclosure relates to a battery control device that controls a battery connected to a power grid, and a battery system that includes this battery control device.

The frequency of electricity in an electric power system (hereafter simply referred to as the system) (hereafter also referred to as the system frequency) changes depending on factors such as changes in the balance between supply and demand. Large changes in electricity frequency can affect consumer equipment and generators, so it is desirable to stabilize the electricity frequency.

Patent Document 1 discloses a technique for controlling the discharge amount of a storage battery connected to a grid in order to stabilize the grid frequency. The grid stabilization device described in Patent Document 1 calculates a limit value imposed on the change in the total output of the generators in a power plant using the rated output of the generators in operation, and controls the discharge amount of the storage battery so that the change in the measured value of the tidal flow of the total output of the generators and the storage battery is within the calculated limit value. In this way, the grid stabilization device described in Patent Document 1 can stabilize the grid frequency because it can limit the change in the output of the entire generators so that it does not affect the change in the grid frequency.

International Publication No. 2013/140916

In a power system, it is required to balance the demand and supply of electricity. For this reason, if one of multiple generators stops due to a breakdown or the like, the other generators that continue to operate automatically increase their output to avoid a shortage of supply. However, this method has the problem that the output of the generators that continue to operate increases sharply, causing fluctuations in the system frequency. In addition, the technology described in Patent Document 1 uses the measured value of the tidal flow of the total output of the generators and the storage battery, so it is not possible to detect that some generators have stopped. This is because, as described above, the other generators automatically increase their output to compensate for the power generation of the stopped generator, so the output value of the entire generators remains almost unchanged even if some generators stop. For this reason, the technology described in Patent Document 1 has the problem that it is not possible to suppress fluctuations in the system frequency that occur when one generator stops and the other generators automatically increase their output.

The present disclosure has been made in consideration of the above, and aims to provide a battery control device that can suppress fluctuations in system frequency that occur when some generators stop and the other generators automatically increase their output.

In order to solve the above-mentioned problems and achieve the object, a storage battery control device according to the present disclosure is a storage battery control device that controls a storage battery connected to a power grid, and includes a measurement data acquisition unit that acquires measurement values of the output of each of a plurality of generators connected to the power grid. The storage battery control device further includes a generator stop determination unit that determines whether each of the plurality of generators has stopped based on the measurement values, and a charge/discharge amount determination unit that increases the discharge amount of the storage battery when the generator stop determination unit determines that a first generator that is one of the plurality of generators has stopped and a second generator that is one of the plurality of generators other than the first generator continues to operate .

The present disclosure has the effect of suppressing fluctuations in system frequency that occur when some generators stop and other generators automatically increase their output.

FIG. 1 is a diagram showing a configuration example of a power system according to an embodiment; FIG. 2 is a diagram showing a configuration example of a storage battery control device according to an embodiment; FIG. 1 is a diagram showing an example of the configuration of a processing circuit when the processing circuit is a circuit including a processor; A flowchart showing an example of control when a generator is stopped in the storage battery control device according to the embodiment. FIG. 13 is a diagram showing a state of control when a generator is stopped according to an embodiment. 11 is a flowchart showing another example of control when the generator is stopped in the storage battery control device according to the embodiment. A flowchart showing an example of a processing procedure after the increase in the discharge amount of the storage battery is started by the processing shown in FIGS.

The battery control device and battery system according to the embodiment are described in detail below with reference to the drawings.

1 is a diagram showing an example of the configuration of a power system according to an embodiment of the present disclosure. As shown in FIG. 1, the power system according to the present embodiment includes a storage battery 1, which is a power storage facility, a storage battery control device 2 that controls the storage battery 1, generators 3-1 to 3-3, and a supply and demand control device 5. The storage battery 1 and the generators (G in FIG. 1) 3-1 to 3-3 are interconnected to the power system 10 via an interconnection line 11. That is, the storage battery 1 and the generators 3-1 to 3-3 are connected to the power system 10. A load (L in FIG. 1) 4 is connected to the power system 10. Note that the load 4 connected to the power system 10 is generally not one, but multiple loads are collectively referred to as the load 4. In addition, power generation facilities other than the generators 3-1 to 3-3 may be connected to the power system 10. The power system 10 is, for example, a small-scale independent system in a remote island, which is called a microgrid, but the power system 10 is not limited thereto.

The supply and demand control device 5 manages the overall supply and demand balance of the power system 10, controlling the start and stop of operation of the generators 3-1 to 3-3 according to the amount of power consumed by the load 4, i.e., the demand, and also controlling the output of the generators 3-1 to 3-3 that are in operation. When generators other than the generators 3-1 to 3-3 are connected to the power system 10, the amount of power generation, which is the output of the generators 3-1 to 3-3, is determined according to the demand so that the supply and demand are balanced throughout the power system 10.

The generators 3-1 to 3-3 are installed, for example, in a power plant, and generate electricity using liquid, gaseous, or solid fuel based on control commands from the supply and demand control device 5. The generators 3-1 to 3-3 are, for example, generators whose power output, i.e., the amount of power generated, can be adjusted. The generators 3-1 to 3-3 are, for example, thermal generators or hydroelectric generators that generate electricity using liquid, gaseous, or solid fuel.

The generators 3-1 to 3-3 have a function to automatically control the output by a speed governor or the like in order to respond to fluctuations in the system frequency. The output of the generators 3-1 to 3-3 is managed by the supply and demand control device 5 as described above, but the control command of the supply and demand control device 5 is generated on the assumption that the generators 3-1 to 3-3 are normal. The supply and demand control device 5 detects a fault in the generators 3-1 to 3-3 based on an accident signal from a protective relay (not shown), but it takes time for the supply and demand control device 5 to detect a fault based on the accident signal after receiving the accident signal and change the control command. Therefore, if one of the generators 3-1 to 3-3 stops due to a fault or the like while all of the generators 3-1 to 3-3 are operating, the other generators among the generators 3-1 to 3-3 that are still operating detect the shortage of supply capacity relative to demand as a change in frequency by the function of the governor and increase their output, thereby preventing an imbalance between supply and demand. That is, each of the generators 3-1 to 3-3 controls its output so that the total output of the generators 3-1 to 3-3 is maintained at a target value. This makes it possible to suppress imbalances in supply and demand as well as fluctuations in system frequency. In this way, the supply volume of a stopped generator can be compensated for by other generators, so the total value of the output of the generators 3-1 to 3-3 remains almost unchanged even if one of the generators 3-1 to 3-3 stops.

The storage battery 1 and the storage battery control device 2 constitute a storage battery system. The storage battery 1 is an electricity storage facility that includes a battery body capable of storing electricity, an inverter that converts the power stored in the battery body into AC power, and a converter that converts the AC power into DC power. The storage battery 1 charges based on a charge command received from the storage battery control device 2, and discharges based on a discharge command received from the storage battery control device 2.

Hereinafter, when the generators 3-1 to 3-3 are referred to without distinction, they will be referred to as generators 3, and when the measuring devices 6-1 to 6-3 are referred to without distinction, they will be referred to as measuring devices 6. In the example shown in FIG. 1, an example is shown in which three generators 3 are provided, but there may be more than one generator 3, and the number of generators 3 is not limited to the example shown in FIG. 1. A measuring device 6 is provided for each generator 3.

As described above, when one of the multiple generators 3 in operation stops, the other generators 3 that continue to operate increase their output. At this time, the other generators 3 that continue to operate increase their output suddenly, and the fuel system, which has a slow response speed, cannot follow up. For this reason, the rotational energy of the rotor of the generator 3 is greatly deviated from the energy input from the combustion system and the energy consumed by converting it into electrical energy, causing the system frequency to become unstable. The smaller the demand for the load 4 of the power system 10, the greater the impact of the system frequency becoming unstable, so the impact of system instability is greater in small-scale systems such as remote islands. In this embodiment, the output of each of the generators 3-1 to 3-3 is measured by the measuring devices 6-1 to 6-3, and the storage battery control device 2 uses the measured values of the measuring devices 6-1 to 6-3 to determine whether any of the generators 3-1 to 3-3 has stopped, and if it is determined that any of the generators 3-1 to 3-3 has stopped, the discharge amount of the storage battery 1 is increased. This makes it possible to suppress the rate of change in the output of the other generators 3 that continue to operate, and to suppress fluctuations in the system frequency. In addition, discharging the storage battery 1 can reduce fuel costs for the generator 3.

In addition, in this embodiment, the stop of the generator 3 is determined using the measured value of the output of the generator 3, so there is no need to receive an accident signal, etc. In order to receive an accident signal, communication with the control system that controls the power grid 10 is necessary, but in this embodiment, there is no need to set up a communication line with the control system. Therefore, even when the storage battery 1 and the storage battery control device 2 are added to an existing facility, and in this embodiment, the stop of the generator 3 is determined using the measured value of the output of the generator 3, it is possible to determine the stop of the generator 3 more quickly than when the stop of the generator 3 is determined using an accident signal.

Figure 2 is a diagram showing an example of the configuration of the storage battery control device 2 of this embodiment. As shown in Figure 2, the storage battery control device 2 of this embodiment includes a measurement data acquisition unit 21, a generator stop determination unit 22, a charge/discharge amount determination unit 23, a command unit 24, and a data storage unit 25.

The measurement data acquisition unit 21 acquires from the measurement device 6 measurement data indicating the measurement value of the output of the generator 3 corresponding to the measurement device 6. That is, the measurement data acquisition unit 21 acquires the measurement value of the output of each of the multiple generators, generators 3-1 to 3-3. The measurement device 6 measures, for example, active power as the output of the generator 3. Note that while one measurement device 6 is shown in FIG. 2, the measurement data acquisition unit 21 acquires from each measurement device 6 measurement data indicating the measurement value of the output of the corresponding generator 3. The measurement data acquisition unit 21 stores the measurement data acquired from each measurement device 6 in the data storage unit 25.

The generator stoppage determination unit 22 determines whether any generator 3 has stopped based on the measurement data stored in the data storage unit 25. That is, the generator stoppage determination unit 22 determines whether a first generator, which is one of the generators 3-1 to 3-3, has stopped based on the measurement values of the output of the generators 3-1 to 3-3. The generator stoppage determination unit 22 may also determine whether any generator 3 has stopped using measurement data acquired directly from the measurement data acquisition unit 21.

The charge/discharge amount determination unit 23 determines the charge/discharge amount of the storage battery 1. For example, when the generator stop determination unit 22 determines that there is a stopped generator 3, the charge/discharge amount determination unit 23 determines the discharge power so as to increase the discharge amount of the storage battery 1. When the generator stop determination unit 22 determines that the first generator has stopped, the charge/discharge amount determination unit 23 increases the discharge amount of the storage battery 1. Any method may be used to increase the charging power, but for example, the charging power to be increased per second, i.e., the slope with respect to time when increasing the charging power, may be determined in advance, or the charging power may be determined based on measurement data. Details of the operation of the charge/discharge amount determination unit 23 will be described later.

The command unit 24 generates a charge command or a discharge command according to the charge/discharge amount determined by the charge/discharge amount determination unit 23, and outputs the generated command to the storage battery 1. The data storage unit 25 stores the measurement data described above.

Here, the hardware configuration of the storage battery control device 2 will be described. The measurement data acquisition unit 21, generator stop determination unit 22, charge/discharge amount determination unit 23, and command unit 24 of the storage battery control device 2 are realized by a processing circuit. In addition, the data storage unit 25 is realized by a memory.

The processing circuit that realizes the measurement data acquisition unit 21, the generator stop determination unit 22, the charge/discharge amount determination unit 23, and the command unit 24 of the storage battery control device 2 may be a circuit equipped with a processor, or may be dedicated hardware. The processing circuit is also called a control circuit.

When the processing circuitry that realizes the measurement data acquisition unit 21, the generator stoppage determination unit 22, the charge/discharge amount determination unit 23, and the command unit 24 is dedicated hardware, the processing circuitry corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination of these.

Figure 3 is a diagram showing an example of the configuration of a processing circuit when the processing circuit is a circuit equipped with a processor. When the processing circuit that realizes the measurement data acquisition unit 21, the generator stop determination unit 22, the charge/discharge amount determination unit 23, and the command unit 24 includes a processor, the processing circuit includes a processor 101 and a memory 102, for example, as shown in Figure 3. When the processing circuit is the processing circuit shown in Figure 3, the functions of the measurement data acquisition unit 21, the generator stop determination unit 22, the charge/discharge amount determination unit 23, and the command unit 24 are realized by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in the memory 102. In the processing circuit, the processor 101 reads and executes the program stored in the memory 102 to realize each function. This program may be provided by a recording medium on which the program is recorded, or may be provided by other means such as a communication medium. The memory 102 is also used as a storage area for storing data required when the processor 101 executes the process.

Here, the processor 101 is, for example, a CPU (Central Processing Unit), a processing device, an arithmetic device, a microprocessor, a microcomputer, or a DSP (Digital Signal Processor). The memory 102 is, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable ROM), or an EEPROM (registered trademark) (Electrically EPROM), a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, or a DVD (Digital Versatile Disc).

The memory that realizes the data storage unit 25 may be a part of the memory 102 described above, or a memory that realizes the data storage unit 25 may be provided separately from the memory 102. In addition, a communication circuit including a receiver and a transmitter may be used to realize the measurement data acquisition unit 21 and the command unit 24.

The functions of the measurement data acquisition unit 21, the generator stop determination unit 22, the charge/discharge amount determination unit 23 and the command unit 24 may be partially realized by dedicated hardware and partially realized by software or firmware.

Next, the operation of the storage battery control device 2 of this embodiment will be described. Below, the control of charging and discharging the storage battery 1 when the operating generator 3 stops due to an accident or the like (hereinafter, also referred to as control when the generator stops) will be described. However, even when the generator 3 does not stop due to an accident or the like, the storage battery control device 2 may perform stabilization control of the system frequency using the storage battery 1 in order to suppress fluctuations in the system frequency due to fluctuations in the supply and demand balance caused by demand fluctuations and fluctuations in the amount of power generated by a power generation facility using natural energy. Any method may be used for the control to suppress fluctuations in the system frequency due to this demand fluctuation, and for example, the control method described in Patent Document 1 can be used. For example, the storage battery control device 2 obtains power generation information indicating the rated output of the operating generator from the supply and demand control device 5, and calculates a limit value imposed on the change in the total output of the generators in the power plant using the operation information. Then, the storage battery control device 2 obtains a measurement value of the current in the interconnection line 11, that is, a measurement value of the total output of the generator and the storage battery 1, and controls the discharge amount of the storage battery 1 so that the change in the measurement value is within the calculated limit value.

Next, the control when the generator is stopped in the battery control device 2 of this embodiment will be described. The measuring devices 6-1 to 6-3 periodically transmit measurement data indicating the measurement values to the battery control device 2. Alternatively, the measurement data acquisition unit 21 of the battery control device 2 may periodically instruct the measuring devices 6-1 to 6-3 to acquire data, and when the measuring devices 6-1 to 6-3 receive the instruction, they may transmit the measurement data to the battery control device 2.

Figure 4 is a flowchart showing an example of control when a generator is stopped in the storage battery control device 2 of this embodiment. It is assumed here that all of the generators 3-1 to 3-3 are normally operated, and are controlled to generate power at the same equal output while in operation. If the supply and demand control device 5 is capable of changing how many of the generators 3-1 to 3-3 are in operation, the storage battery control device 2 obtains information from the supply and demand control device 5 indicating the generators 3 that have been instructed to operate by the supply and demand control device 5 (hereinafter referred to as operating generators 3). The storage battery control device 2 then performs the process shown in Figure 4 for the operating generators 3.

As shown in FIG. 4, the measurement data acquisition unit 21 acquires measurement data from the measurement devices 6-1 to 6-3 (step S1). As described above, the measurement data is data indicating the measurement value of the output of each of the generators 3-1 to 3-3. The measurement data acquisition unit 21 stores the measurement data in the data storage unit 25. The generator stop determination unit 22 refers to the measurement data stored in the data storage unit 25 and determines whether there is a generator 3 whose measurement value is less than the first threshold value (step S2). The first threshold value is a value corresponding to the output when the generator 3 is stopped, and is set to a small value such as, for example, 1.5 times the measurement error or the maximum value of the measurement error of the measurement devices 6-1 to 6-3. The first threshold value is not limited to the above-mentioned example, as long as it is a threshold value for determining that the generator 3 has stopped due to an accident or the like.

If there is a generator 3 whose measurement value is less than the first threshold value (step S2: Yes), the generator stop determination unit 22 determines whether the measurement value of the other generators 3, i.e., the measurement value of the generator 3 whose measurement value was determined to be less than the first threshold value in step S2, is equal to or greater than the second threshold value (step S3). The second threshold value may be the same value as the first threshold value, or may be a value greater than the first threshold value. The second threshold value is a threshold value for determining that the other generators 3 are continuing to operate.

If the measurement value of the other generators 3 is equal to or greater than the second threshold value (step S3 Yes), the charge/discharge amount determination unit 23 determines the discharge amount so as to increase the discharge amount of the storage battery 1 (step S4). In detail, if the measurement value of the other generators 3 is equal to or greater than the second threshold value, the generator stoppage determination unit 22 notifies the charge/discharge amount determination unit 23 that some generators 3 have stopped and the other generators 3 are continuing to operate, i.e., that some generators have stopped. When the charge/discharge amount determination unit 23 receives the notification that some generators have stopped, it determines the discharge amount so as to increase the discharge amount of the storage battery 1.

In step S4, the charge/discharge amount determination unit 23 may increase the charge amount so that the increase per unit time is a constant value, or may increase the charge amount according to a predetermined function of time. In addition, the charge/discharge amount determination unit 23 may determine the increase per unit time according to the previously acquired measurement value for each generator 3 based on the measurement data stored in the data storage unit 25, or may calculate the average value of the measurement values over a certain period up to the previous time and determine the increase per unit time according to the average value.

After step S4, the command unit 24 transmits a discharge command to the storage battery 1 (step S5). In detail, the charge/discharge amount determination unit 23 notifies the command unit 24 of the discharge amount determined in step S4. The command unit 24 generates a discharge command based on the notified discharge amount, and transmits the discharge command to the storage battery 1. This increases the discharge amount from the storage battery 1.

If the answer is No in step S2 and if the answer is No in step S3, the battery control device 2 ends the process without changing the charge/discharge amount of the battery 1. As described above, in the example shown in FIG. 4, the generator stop determination unit 22 determines that the first generator has stopped when the measurement value of the first generator among the generators 3 is less than the first threshold value and the measurement value of the second generator, which is one of the multiple generators 3 other than the first generator, is equal to or greater than the second threshold value.

Figure 5 is a diagram showing the state of control when a generator is stopped in this embodiment. In Figure 5, the horizontal axis indicates time, and the vertical axis indicates power. Figure 5 shows an example in which generator 3-1, out of generators 3-1 to 3-3 in operation, has stopped due to an accident or the like. Output 201 indicates the output of generator 3-1 that has stopped due to an accident or the like, and output 202 indicates the output of generator 3-2, the other generator 3 that continues to operate even after generator 3-1 has stopped. The output of generator 3-3 is the same as output 202. Discharge amount 203 indicates the discharged power of storage battery 1.

As shown in FIG. 5, before the generator 3-1 stops, the output 201 and the output 202 are almost the same value, but when the generator 3-1 stops at time T ₁ , the output 201 drops sharply. On the other hand, the output 202 increases sharply due to automatic control by the governor as the output of the generator 3-1 drops. If the output of the generator 3-2 is increased sharply, the system frequency fluctuates due to the problem of the response speed of the combustion system as described above. For this reason, in this embodiment, when the storage battery control device 2 detects the stop of the generator 3-1, it suppresses the output of the generators 3-2 and 3 by increasing the discharge amount 203 of the storage battery 1. This makes it possible to suppress the fluctuation of the system frequency. In the example shown in FIG. 4 described above, whether the generator 3 has stopped is determined based on whether the measured value of the output of the generator 3 is less than the first threshold value, and when the stop of the generator 3 is detected, the discharge amount 203 of the storage battery 1 increases. As a result, the output 202 of the generator 3-2 automatically and gradually decreases. Although FIG. 5 shows an example in which the generator 3-1 has stopped, the same operation is performed when the generator 3-2 or the generator 3-3 has stopped.

It is also possible that the measured output value of generator 3 may fall below the first threshold value due to reasons other than the stoppage of generator 3, such as a temporary change in demand. In the case of a change in demand, the output of other generators 3 is expected to change in the same way. Therefore, in order to distinguish this from a change in demand, in the example shown in FIG. 4, a determination is made in step S3 as to whether the output of other generators 3 is equal to or greater than the second threshold value.

The battery control device 2 performs the process shown in FIG. 4 each time it receives measurement data from the measuring devices 6-1 to 6-3 until the discharge amount of the battery 1 is increased in steps S4 and S5. Note that although the measurement data transmission cycle of the measuring devices 6-1 to 6-3 is the same, the timing at which the battery control device 2 receives the measurement data from the measuring devices 6-1 to 6-3 does not have to be simultaneous. The battery control device 2 only needs to perform the process shown in FIG. 4 using the measurement data received from the measuring devices 6-1 to 6-3 within the same transmission cycle.

In the example shown in FIG. 4, when the measured value of the output of a certain generator 3 has dropped below the first threshold and the measured value of the output of another generator 3 has not dropped, i.e., the measured value of the output of another generator 3 is equal to or greater than the second threshold, it is determined that the generator 3 whose measured value has dropped has stopped due to an accident or the like. However, the method of determining whether a generator 3 has stopped based on the measured value is not limited to the above example.

FIG. 6 is a flowchart showing another example of the control when the generator is stopped in the storage battery control device 2 of this embodiment. Step S1 is the same as the example shown in FIG. 4. After step S1, the generator stop determination unit 22 determines whether the measurement value of some of the generators is equal to or less than the threshold value and the decrease rate is equal to or greater than the rate threshold value (step S6). The decrease rate is the amount of decrease in the measurement value per unit time. In detail, for example, when the measurement value indicated by the latest measurement data is smaller than the measurement value indicated by the measurement data received one time before, the generator stop determination unit 22 calculates the decrease rate by subtracting the measurement value indicated by the latest measurement data from the measurement value indicated by the measurement data received one time before. The generator stop determination unit 22 determines whether the measurement value indicated by the latest measurement data is equal to or less than the threshold value and the decrease rate is equal to or greater than the rate threshold value for each generator 3. When the measurement value indicated by the latest measurement data of some of the generators 3 is equal to or less than the threshold value and the decrease rate is equal to or greater than the rate threshold value, and the other generators 3 do not satisfy this condition, the generator stop determination unit 22 determines Yes in step S6. If the measurement values indicated by the latest measurement data of all operating generators 3 are equal to or less than the threshold value and the decrease rate is equal to or greater than the rate threshold value, the generator stoppage determination unit 22 determines No in step S6. Note that the decrease rate may be calculated by subtracting the measurement value indicated by the latest measurement data from the measurement value indicated by the previously received measurement data, and dividing the result by the transmission period of the measurement data. However, if the transmission period is constant, it is not necessary to regard the transmission period as a unit time and perform the process of dividing by the transmission period.

The threshold value is a threshold value for determining that a sudden output is occurring due to a stoppage due to an accident or the like. This threshold value may be a value similar to the first threshold value described above, but may be set to a somewhat large value, such as a value of about 1/3 of the average value of the output during normal operation of the generator 3. In addition, the reduction rate is not limited to the difference between the measurement data received one time ago and the latest measurement data, and may be calculated based on the most recent three or more measurement data. For example, the reduction rate may be an average value of a value obtained by subtracting the measurement value indicated by the measurement data received two times ago from the measurement value indicated by the measurement data received three times ago, a value obtained by subtracting the measurement value indicated by the measurement data received one time ago from the measurement value indicated by the measurement data received two times ago, and a value obtained by subtracting the measurement value indicated by the latest measurement data from the measurement value indicated by the measurement data received one time ago.

If the measured value is equal to or less than the threshold value and the decrease rate is equal to or greater than the rate threshold value (Yes in step S6), steps S4 and S5 are performed as in the example shown in Fig. 4. If No in step S6, the battery control device 2 ends the process without changing the charge/discharge amount of the storage battery 1. As described above, in the example shown in Fig. 6, the generator stop determination unit 22 determines that the first generator has stopped when the measured value of the first generator among the generators 3 is equal to or less than the threshold value and the decrease rate per unit time of the measured value of the first generator is equal to or greater than the rate threshold value.

In the example shown in FIG. 6, after step S6, the generator stop determination unit 22 may determine whether the measured value of the output of the other generators 3 is increasing. If the measured value of the output of the other generators 3 is increasing, the storage battery control device 2 then performs steps S4 and S5, and if the output of the other generators 3 is not increasing, ends the process.

The decision to stop the generator 3 may be made based on the output of the generator 3, and the specific method may be the method shown in FIG. 4, the method shown in FIG. 6, or other examples.

There is no particular restriction on the method of controlling the charge and discharge amount after the increase in the discharge amount of the storage battery 1 is started by the processing exemplified in FIG. 4 and FIG. 6. For example, when the output of the generator 3, which continues to operate, decreases to the output before the accident occurs after the discharge amount is increased, the increase in the discharge amount is stopped. In the example shown in FIG. 5, the output 202 of the generator 3-2 is automatically gradually decreased by increasing the discharge amount 203 of the storage battery 1 from time T _1. The charge and discharge amount determination unit 23 of the storage battery control device 2 acquires measurement data of the output of the generator 3-2 via the data storage unit 25 and the generator stop determination unit 22, and stops the increase in the discharge amount when the output of the generator 3-2 decreases to the output before the accident occurs, i.e., before the generator 3-1 is stopped. However, if the discharge output of the storage battery reaches an upper limit value before the increase in the discharge amount is stopped, the charge and discharge amount determination unit 23 stops the increase in the discharge amount when the upper limit value is reached. The charge and discharge amount determination unit 23 may acquire measurement data of the output of the generator 3-2 directly from the data storage unit 25. After the output of the generator 3-2 is reduced, the output is gradually increased so as to operate at a high efficiency point until the output of the generator 3-2 is equal to that of two generators. In the example shown in FIG. 5, the output of the generator 3-1 starts to increase at time _T2 , a certain time after the output reduction of the generator 3-2 ends, but the timing of the increase in the output is not limited to this example. The charge/discharge amount determination unit 23 of the storage battery control device 2 reduces the discharge amount 203 in accordance with the reduction in the output of the generator 3-2 based on the measurement data of the output of the generator 3-2. By the above operation, the generator 3-2 that continues to operate can increase its output gradually, so that the output of the stopped generator 3-1 can be compensated for by the output of the other generator 3-2 while suppressing the fluctuation of the system frequency due to the slow response speed of the combustion system. In addition, when there are multiple generators 3 that continue to operate other than the stopped generator 3, the charge/discharge amount determination unit 23 stops the increase in the discharge amount, for example, when the measurement data of the output of all of the multiple generators 3 has decreased to the output level before the accident occurred or when the upper limit of the discharge amount has been reached. As described above, the method of controlling the charge/discharge amount after the discharge amount of the storage battery 1 starts to increase is not limited to this example, and any control method that suppresses a sudden increase in the output of the generator 3-2 may be used. Also, the example shown in Fig. 5 is just one example, and the output of each generator 3 and the discharge amount of the storage battery 1 are determined by various conditions such as the load state and the control method of the generator 3.

Figure 7 is a flowchart showing an example of a processing procedure after the increase in the discharge amount of the storage battery 1 has started by the processing exemplified in Figures 4 and 6. As shown in Figure 6, the measurement data acquisition unit 21 acquires measurement data from the measurement devices 6-1 to 6-3, similar to step S1 (step S11). The measurement data acquisition unit 21 stores the measurement data in the data storage unit 25. The generator stop determination unit 22 refers to the measurement data stored in the data storage unit 25 and determines whether the discharge amount of the storage battery 1 has exceeded the measurement value of the other generators 3 (step S12).

When the discharge amount of the storage battery 1 exceeds the measurement value of the other generator 3 (step S12 Yes), the charge/discharge amount determination unit 23 determines the discharge amount so as to maintain the discharge amount of the storage battery 1 (step S13). In detail, when the discharge amount of the storage battery 1 exceeds the measurement value of the other generator 3, the generator stop determination unit 22 notifies the charge/discharge amount determination unit 23 that the discharge amount of the storage battery 1 has exceeded the measurement value of the other generator 3. Upon receiving the notification, the charge/discharge amount determination unit 23 determines the discharge amount so as to maintain the discharge amount of the storage battery 1.

If the discharge amount of the storage battery 1 does not exceed the measurement value of the other generator 3 (step S12 No), the charge/discharge amount determination unit 23 determines the discharge amount so as to increase the discharge amount of the storage battery 1, as in step S4 (step S15). In detail, if the discharge amount of the storage battery 1 does not exceed the measurement value of the other generator 3, the generator stop determination unit 22 notifies the charge/discharge amount determination unit 23 that the discharge amount of the storage battery 1 does not exceed the measurement value of the other generator 3. Upon receiving the notification, the charge/discharge amount determination unit 23 determines the discharge amount so as to increase the discharge amount of the storage battery 1.

After step S13 and after step S15, the command unit 24 transmits a discharge command to the storage battery 1 (step S14). Through the above process, the discharge amount of the storage battery 1 increases until the discharge amount of the storage battery 1 exceeds the measurement value of the other generator 3, and when the discharge amount of the storage battery 1 exceeds the measurement value of the other generator 3, the discharge amount of the storage battery 1 is maintained at a constant value. After that, when a time of ΔT has elapsed from the start of the increase in the discharge amount of the storage battery 1, the generator stop determination unit 22 notifies the charge/discharge amount determination unit 23 of the fact. Upon receiving the notification, the charge/discharge amount determination unit 23 gradually reduces the discharge amount of the storage battery 1. At this time, the amount of power generated by the generator 3 increases by the amount of the decrease in the discharge amount, so the rate of decrease in the discharge amount is determined so that the output of the generator 3 increases while suppressing fluctuations in the system frequency, taking into account the response speed of the combustion system of the generator 3, etc.

In the above example, an example was described in which one generator 3 is stopped when three generators 3 are in operation, but the number of generators 3 in operation and the number of generators 3 that are stopped are not limited to this example. For example, by performing similar control even if two of the three generators 3 are stopped, it is possible to suppress fluctuations in system frequency that occur when one generator stops and the other generators automatically increase their output.

As described above, in this embodiment, the storage battery control device 2 determines whether the generators 3 have stopped based on the measured output of each generator 3, and increases the discharge amount of the storage battery 1 when it determines that the generators 3 have stopped. This makes it possible to suppress fluctuations in system frequency that occur when some generators stop and the other generators automatically increase their output. In addition, since there is no need to communicate with a control system that monitors accident signals, there is no need to introduce communication equipment for this purpose, and the configuration can be simplified. In addition, it is possible to suppress increases in fuel costs for other generators.

The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or the embodiments may be combined with each other. In addition, parts of the configurations may be omitted or modified without departing from the spirit of the invention.

1 Storage battery, 2 Storage battery control device, 3-1 to 3-3 Generators, 4 Load, 5 Supply and demand control device, 6, 6-1 to 6-3 Measurement device, 10 Power system, 11 Interconnection line, 21 Measurement data acquisition unit, 22 Generator stop determination unit, 23 Charge/discharge amount determination unit, 24 Command unit, 25 Data storage unit.

Claims (5)

A battery control device that controls a battery connected to a power grid,
a measurement data acquisition unit that acquires measurement values of the outputs of each of a plurality of generators connected to the power grid;
a generator stoppage determination unit that determines whether each of the plurality of generators has stopped based on the measurement values;
a charge/discharge amount determination unit that increases a discharge amount of the storage battery when the generator stop determination unit determines that a first generator that is one of the plurality of generators has stopped and that a second generator that is one of the plurality of generators other than the first generator continues to operate ;
A battery control device comprising: A battery control device that controls a battery connected to a power grid,
a measurement data acquisition unit that acquires measurement values of the outputs of each of a plurality of generators connected to the power grid;
a generator stoppage determination unit that determines whether each of the plurality of generators has stopped based on the measurement values;
a charge/discharge amount determination unit that increases a discharge amount of the storage battery when the generator stop determination unit determines that a first generator, which is one of the plurality of generators, has stopped;
Equipped with
A battery control device characterized in that the generator stoppage determination unit determines that the first generator has stopped when the measurement value of the first generator is less than a first threshold value and the measurement value of a second generator which is one of the plurality of generators other than the first generator is greater than or equal to a second threshold value. The battery control device according to claim 1, characterized in that the generator stop determination unit determines that the first generator has stopped when the measured value of the first generator is equal to or less than a threshold value and the amount of decrease per unit time of the measured value of the first generator is equal to or greater than a rate threshold value. A battery control device according to any one of claims 1 to 3, characterized in that each of the multiple generators controls its output so that the total output of the multiple generators is maintained at a target value. A storage battery connected to a power grid;
A battery control device according to any one of claims 1 to 4, which controls the battery;
A storage battery system comprising:

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