Uninterruptible power source device, power system, control device, and control method

Abstract

To supply stable power to a load device that is connected to a power grid.SOLUTION: An uninterruptible power source device according to the present embodiment can be connected to a power line through which power is supplied from a power grid to a load device, and includes a chargeable / dischargeable storage battery, a monitoring unit that monitors the state of charge of the power storage battery, and a control unit that controls charging / discharging from the storage battery to the power line on the basis of the difference between a first frequency which is the frequency of the power grid and a second frequency which serves as reference for the power grid, and the state of charge of the storage battery.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present embodiment relates to an uninterruptible power supply, a power system, a control device, and a control method. [Background technology]

[0002] Some uninterruptible power supplies have a function of supporting the power system by charging and discharging the uninterruptible power supply's storage battery in response to changes in the power system frequency (system frequency) and providing adjustment capabilities such as fast frequency response and primary frequency control.

[0003] However, when the UPS battery supplies regulation power to the power grid, the state of charge (SoC) of the battery may decrease, and the amount of power that the UPS can supply to the load during a power outage may fall short of what is needed. In this case, the UPS cannot supply stable power to the load. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022 / 233457 [Non-patent literature]

[0005] [Non-Patent Document 1] I. Alapera, J. Paananen, K. Dalen and S. Honkapuro, "Fast frequency response from a UPS system of a data center background and pilot results", 16th Int. Conf. Eur. Energy Mark. EEM, pp. 1-5, 2019-September. Summary of the Invention [Problem to be solved by the invention]

[0006] The present embodiment provides an uninterruptible power supply device, a power system, a control device, and a control method that enable stable power supply to a load device connected to a power grid. [Means for solving the problem]

[0007] The uninterruptible power supply of this embodiment is an uninterruptible power supply that can be connected to a power line through which power is supplied from a power system to a load device, and includes a chargeable and dischargeable storage battery, a monitoring unit that monitors the charge state of the storage battery, and a control unit that controls charging and discharging from the storage battery to the power line based on the difference between a first frequency, which is the frequency of the power system, and a second frequency that is the reference frequency of the power system, and the charge state of the storage battery. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of a power system according to an embodiment of the present invention. [Diagram 2] 4A and 4B are diagrams showing examples of a first charge / discharge pattern and a second charge / discharge pattern. [Diagram 3] FIG. 4 is a diagram showing an example of a relationship between a first threshold value, a second threshold value, and a state of charge. [Figure 4] FIG. 11 is a diagram showing another example of the first charge / discharge pattern and the second charge / discharge pattern. [Diagram 5] 4A and 4B are diagrams showing examples of a first charge / discharge pattern and a third charge / discharge pattern. [Figure 6] FIG. 11 is a diagram showing another example of the first charge / discharge pattern and the third charge / discharge pattern. [Figure 7] 13 is a flowchart of an example of a process for determining a charge / discharge pattern in a charge / discharge amount calculation unit. [Figure 8] FIG. 1 is a diagram showing an example of a power system according to an embodiment of the present invention. [Figure 9] FIG. 1 is a diagram showing an example of a power system according to an embodiment of the present invention. [Figure 10] A diagram showing the relationship between changes in system frequency and the adjustment power supplied. [Figure 11] FIG. 13 is a diagram showing an example of a power system according to a fourth embodiment. [Figure 12] FIG. 1 shows an example of the configuration of a power system with four UPS units. [Figure 13] FIG. 13 is a diagram showing an example in which the same first charge / discharge pattern is applied to two UPS units. [Figure 14] FIG. 4 is a diagram showing an example of a first charge / discharge pattern applied to each of two UPS units. [Figure 15] FIG. 13 is a diagram showing another example of the first charge / discharge pattern applied to each of the two UPS units. [Figure 16] 16 is a diagram showing an example in which the first charge / discharge pattern of the UPS-lead storage battery shown in FIG. 15 is partially modified. [Figure 17] FIG. 13 is a diagram showing another example of the first charge / discharge pattern applied to each of the two UPS units. [Figure 18] FIG. 13 is a diagram showing an example of the configuration of another power system according to the present embodiment. [Figure 19] FIG. 4 is a diagram showing an example of a first charge / discharge pattern in the case where the charge / discharge pattern changes stepwise. [Figure 20] FIG. 13 is a diagram showing an example of a power system according to a sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (First embodiment) FIG. 1 shows an example of a power system according to the present embodiment. The power system in FIG. 1 includes an uninterruptible power supply 100 (UPS: Uninterruptible Power System), a load device 200, and a power system 300. The power system 300 is a system that generates power using a power generation facility and transmits the generated power to a power receiving facility of the consumer, thereby supplying power to the consumer. The load device 200 is an example of a power receiving facility of the consumer, and is, for example, a server installed in a facility such as a data center or a factory. The uninterruptible power supply 100 includes a rechargeable storage battery 110, and supports the operation of the power system 300 by supplying (discharging or receiving) an adjustment capability to the power system 300. The supply of the adjustment capability can stabilize the power supply from the power system 300 to the consumer. The uninterruptible power supply 100 may supply (discharge) power to the load device 200 in parallel at all times, separately from the supply of the adjustment capability to the power system 300. In the following description, the power supply of the uninterruptible power supply 100 will be described with a focus mainly on the supply of the adjustment capability. The load device 200 operates on power supplied from the power grid 300 and power supplied from the uninterruptible power supply 100 (power supplied as regulating power and, if there is separate power supplied continuously, that power). The uninterruptible power supply 100 is installed on the consumer side and is separate from the equipment on the power grid 300 side.

[0010] The UPS 100 includes a storage battery 110, an adjustment unit 120, a DC / DC conversion unit 130, a storage battery monitoring unit 140, a voltage sensor 150, a frequency measurement unit 160, a charge / discharge amount calculation unit 170, and a charge / discharge instruction unit 180 (control unit). The adjustment unit 120 includes an AC / DC conversion unit 121 and a DC / AC conversion unit 122.

[0011] The storage battery 110 is a battery that can be charged and discharged. The storage battery 110 is, for example, a lithium ion battery or a lead storage battery. The storage battery 110 can be charged by receiving power supplied from the power system 300 via the AC / DC conversion unit 121 and the DC / DC conversion unit 130. The storage battery 110 can also supply power to the load device 200 by discharging the stored power via the DC / DC conversion unit 130 and the DC / AC conversion unit 122.

[0012] The DC / DC conversion unit 130 is an inverter that controls charging and discharging of the storage battery 110 under instructions from the charge / discharge instruction unit 180. The inverter may be a constant voltage inverter or a constant current inverter.

[0013] The storage battery monitoring unit 140 monitors the state of charge (SoC) of the storage battery 110. The state of charge is represented, for example, by the ratio of the amount of stored power to the battery capacity, and is a value between 0 and 1. However, the state of charge may represent the value of the amount of stored power itself, or may be represented by a rank.

[0014] The voltage sensor 150 is connected to the power system 300, and measures the voltage of the power system 300 (system voltage).

[0015] The frequency measurement unit 160 measures the frequency of the power system 300 (system frequency) from the measurement information of the voltage sensor 150.

[0016] The charge / discharge amount calculation unit 170 holds a plurality of pieces of information on charge / discharge patterns that associate the difference between the system frequency and the reference frequency, i.e., the deviation of the system frequency from the reference frequency (frequency deviation), with the charge / discharge power (charge power or discharge power). The charge / discharge power is also called adjustment power. The charge / discharge amount calculation unit 170 can selectively switch the charge / discharge pattern to be used from among the plurality of charge / discharge patterns. As an example, the charge / discharge ability calculation unit 170 can switch between a first charge / discharge pattern and a second charge / discharge pattern. The selected charge / discharge pattern is called the used charge / discharge pattern. The charge / discharge amount calculation unit 170 determines the difference between the reference frequency of the system frequency and the system frequency (measured frequency of the power system 300) as a frequency deviation (hereinafter, deviation), and specifies the adjustment power corresponding to the deviation in the used charge / discharge pattern. In this embodiment, the difference is calculated by "measured frequency-reference frequency". However, this definition of the difference is an example, and the direction of the calculation may be reversed, or the difference may be defined by the ratio of the two. The charge / discharge pattern may be configured by a database such as a lookup table, or may be a function that calculates an output variable according to the values ​​of input variables. In this case, the input variables are assigned the deviation values, and the output variable output from the function represents the adjustment capacity.

[0017] The charge / discharge instruction unit 180 is a control unit that controls the DC / DC conversion unit 130 so that charging / discharging is performed with the adjustment power calculated by the charge / discharge amount calculation unit 170. The charge / discharge instruction unit 180 sends instruction information to the DC / DC conversion unit 130 to charge or discharge with the charge / discharge power calculated by the charge / discharge amount calculation unit 170. The DC / DC conversion unit 130 controls the storage battery 110 so that charging or discharging is performed with the power according to the instruction information.

[0018] Hereinafter, examples of a plurality of switchable charge / discharge patterns and switching control of the charge / discharge pattern in the charge / discharge amount calculation unit 170 will be described with reference to Figs.

[0019] FIG. 2 shows examples of the first and second charge / discharge patterns. When the amount of charge (amount of charge) of the storage battery 110 is less than a first threshold, the second charge / discharge pattern is used. When the amount of charge of the storage battery 110 is equal to or greater than the first threshold and less than the second threshold, the first charge / discharge pattern is used. When it is equal to or greater than the second threshold, the pattern will be described later. FIG. 3 shows an example of the relationship between the first and second thresholds and the state of charge. A value equal to or greater than the first threshold and less than the second threshold corresponds to a normal range, a value less than the first threshold corresponds to a range smaller than the normal range, and a value equal to or greater than the second threshold corresponds to a range larger than the normal range.

[0020] As shown in FIG. 2, in the first charge / discharge pattern, when the deviation from the reference frequency is a first predetermined value (here, zero), no charge / discharge is performed, and when the deviation is greater than zero, i.e., when the system frequency is greater than the reference frequency, the greater the deviation, the greater the power that charges the storage battery 110. Zero corresponds to the first predetermined value. However, when the deviation is greater than 0.2 Hz (=50.2 Hz-50 Hz), the charging power is constant. When the sum of the charging power by the regulation capability and the power consumption of the load device 200 exceeds the rated value of the AC / DC conversion unit 121, the charging power by the regulation capability may be reduced. When the deviation is less than zero, i.e., when the system frequency is less than the reference frequency, the smaller the deviation, the greater the power that is discharged from the storage battery 110. However, when the deviation is less than -0.2 Hz (=49.8 Hz-50 Hz), the discharging power is constant. In addition, although the reference frequency of the system frequency is set to 50 Hz here, it may be 60 Hz. Discharging the storage battery 110 makes the power received by the UPS from the system appear to decrease. When the amount of discharge from the storage battery 110 becomes greater than the power consumption of the load device connected to the UPS, the power may be discharged to the power system 300 side as regenerative power to the power system 300. When the power is discharged to the power system 300 side, it may be consumed within the premises by another load device within the premises where the UPS is installed. In order to prevent reverse power flow due to the regenerative power to the power system 300, when regenerative power to the power system 300 is generated, the discharge power from the storage battery 110 as regulating power may be reduced. The UPS may be connected to a reverse power relay (RPR) to stop the regulating power supply of the UPS when reverse power flow occurs.

[0021] In the second charge / discharge pattern, when the deviation is a predetermined value D11, no charge / discharge is performed, and when the deviation is greater than the predetermined value D11 (second predetermined value), the larger the deviation, the greater the power with which the storage battery 110 is charged. However, when the deviation becomes greater than D12, the charging power is kept constant. When the deviation is smaller than the predetermined value D11, the smaller the deviation, the greater the power with which the storage battery 110 is discharged. However, when the deviation becomes smaller than -0.2 Hz, the discharging power is kept constant. The predetermined value D12 is a real number greater than zero. The predetermined value D11 is a real number less than zero.

[0022] When the charge state of the storage battery 110 becomes less than the first threshold from a state equal to or greater than the first threshold, the charge / discharge amount calculation unit 170 switches from the first charge / discharge pattern to the second charge / discharge pattern, thereby preventing the storage battery 110 from becoming overdischarged (insufficient remaining capacity). When the charge state of the storage battery 110 becomes greater than or equal to the first threshold from a state less than the first threshold, the charge / discharge pattern is switched from the second charge / discharge pattern to the first charge / discharge pattern and power is supplied to the power system 300, thereby providing a stable supply of power to the load device 200.

[0023] Fig. 4 shows another example of the first charge / discharge pattern and the second charge / discharge pattern. As in Fig. 2, when the charge state of the storage battery 110 is less than the first threshold, the second charge / discharge pattern is used, and when the charge state of the storage battery 110 is equal to or greater than the first threshold and less than the second threshold, the first charge / discharge pattern is used. However, although the first charge / discharge pattern is the same as in Fig. 2, the content of the second charge / discharge pattern is different from that in Fig. 2.

[0024] In the second charge / discharge pattern, when the deviation is equal to or less than a third predetermined value (zero in this case), no charge / discharge is performed, and when the deviation is greater than zero, the greater the deviation, the greater the power that charges the storage battery 110. However, when the deviation is greater than 0.2 Hz, the charging power is kept constant. When the deviation is equal to or less than zero, no discharge is performed, thereby preventing the storage battery 110 from becoming over-discharged.

[0025] Fig. 5 shows examples of the first charge / discharge pattern and the third charge / discharge pattern. When the charge state of the storage battery 110 is equal to or greater than the first threshold and less than the second threshold, the charge / discharge amount calculation unit 170 uses the first charge / discharge pattern, and when the charge state of the storage battery 110 is equal to or greater than the second threshold, the charge / discharge pattern is used. The first charge / discharge pattern is the same as that shown in Fig. 2. The second threshold is shown in Fig. 3 described above. The third charge / discharge pattern will be described below.

[0026] As shown in Fig. 5, in the third charge / discharge pattern, when the deviation from the reference frequency is a predetermined value D13 (fourth predetermined value), no charge / discharge is performed, and when the deviation is greater than the predetermined value D13, the greater the deviation, the greater the power with which the storage battery 110 is charged. However, when the deviation is greater than 0.2 Hz, the charging power is kept constant. The predetermined value D13 is a real number greater than zero. When the deviation is smaller than the predetermined value D13, the smaller the deviation, the greater the power with which the storage battery 110 is discharged. However, when the deviation is smaller than a predetermined value D14, the discharging power is kept constant. The predetermined value D14 is a real number less than zero.

[0027] The charge / discharge amount calculation unit 170 can prevent the storage battery 110 from becoming overcharged (excessive remaining capacity) by switching from the first charge / discharge pattern to the third charge / discharge pattern when the charge state of the storage battery 110 becomes equal to or greater than the second threshold from a state below the second threshold.

[0028] Fig. 6 shows another example of the first charge / discharge pattern and the third charge / discharge pattern. When the charge state of the storage battery 110 is equal to or greater than the first threshold and less than the second threshold, the first charge / discharge pattern is used as in Fig. 5. When the charge state of the storage battery 110 is equal to or greater than the second threshold, the third charge / discharge pattern is used. The first charge / discharge pattern is the same as Fig. 2, but the content of the third charge / discharge pattern is different.

[0029] In the third charging / discharging pattern, when the deviation is equal to or greater than a fifth predetermined value (zero in this case), no charging or discharging is performed, and when the deviation is smaller than zero, the smaller the deviation, the greater the power that is discharged from the storage battery 110. However, when the deviation becomes smaller than -0.2, the discharge power is kept constant. When the deviation is equal to or greater than zero, no charging is performed, thereby preventing the storage battery 110 from becoming overcharged.

[0030] 7 is a flowchart of an example of a process in which the charge / discharge amount calculation unit 170 determines a charge / discharge pattern. The charge / discharge amount calculation unit 170 acquires information on the state of charge (SoC) of the storage battery 110 from the storage battery monitoring unit 140 (S10), and if the state of charge is less than a first threshold, determines a second charge / discharge pattern (S60). If the state of charge is equal to or greater than the first threshold and less than a second threshold, determines a first charge / discharge pattern (S40), and if the state of charge is equal to or greater than the second threshold, determines a third charge / discharge pattern (S50).

[0031] As described above, according to the first embodiment, by switching the charging / discharging pattern of the power supplied to the load device 200 depending on the charging state of the storage battery 110, it is possible to supply a stable adjustment power to the power system 300 while preventing the storage battery 110 from entering an overcharged or overdischarged state.

[0032] In this embodiment, the charge state of the storage battery 110 is acquired, a charge / discharge pattern corresponding to the charge state is selected, and the adjustment capability (charge / discharge capability) to be supplied to the power system 300 is determined based on the selected charge / discharge pattern and the frequency deviation. As another method, a function reflecting the relationship between the charge state, each charge / discharge pattern, and the frequency deviation may be generated in advance, and the adjustment capability may be determined using this function. For example, a variable of the charge state and a variable of the frequency deviation are used as input variables of the function, and a variable of the adjustment capability (charge / discharge capability) is used as an output variable. In this case, the acquired charge state and the calculated frequency deviation are assigned to the respective input variables to calculate the function, and the output variable is obtained as the calculation result, so that the adjustment capability can be determined. This may allow the adjustment capability to be calculated more quickly and supplied to the power system 300.

[0033] Second embodiment FIG. 8 shows an example of a power system according to this embodiment. The same reference numerals are used for elements with the same names as those in FIG. 1, and the description will be omitted as appropriate. The following description will focus on the parts that are different from the power system in FIG. 1. The battery monitor 140, the voltage sensor 150, the frequency measurement unit 160, the charge / discharge amount calculation unit 170, and the charge / discharge instruction unit 180 are separated from the housing of the UPS 100 and incorporated in a control device 135 that is independent of the UPS 100. The control device 135 is connected to the UPS 100 via an external interface cable (for example, a bus cable). Instruction information can be transmitted from the charge / discharge instruction unit 180 to the DC / DC 130 via the interface cable. The battery monitor 140 can obtain information indicating the state of the battery 110 via the interface cable. The UPS 100 and the control device 135 may be connected wirelessly in addition to being connected by wire. In this case, a wireless communication unit may be provided in the control device 135 and the UPS 100.

[0034] In the example of FIG. 8, all of the components 140 to 170 are separate from the UPS 100. However, only some of the components 140 to 170 may be separated from the UPS 100, and the rest may be included in the control device 135.

[0035] As described above, according to the second embodiment, the functions of this embodiment can be easily realized by separating all or part of the functions of this embodiment from UPS 100 and externally connecting a control device equipped with the separated functions to an existing UPS.

[0036] (Third embodiment) FIG. 9 shows an example of a power system according to this embodiment. In the power system of FIG. 9, the UPS 100 includes a timer 190. In the first charge / discharge pattern of the first embodiment, when the system frequency becomes smaller than the reference frequency, the UPS 100 continues to discharge with power according to the frequency deviation. In this embodiment, however, a limit is set on the time for discharging. Specifically, after discharging starts, discharging is performed only for a first time, and when the first time has elapsed (without switching to charging or stopping discharging), the AC / DC converter 121 is stopped or the supply of regulating power to the power system 300 is stopped regardless of the value of the deviation at that time. However, even after the timer 190 has been operated, the power supply to the load device connected to the UPS (discharging to protect the load device as an original function of the UPS, not as the regulating power of the power system 300) may be continued. This embodiment can be said to change the pattern part of the discharge area of ​​the first charge / discharge pattern in the first embodiment.

[0037] The upper diagram in Figure 10 shows the change in system frequency. For example, it shows an example in which a thermal power plant or other power plant stops operating due to an earthquake or other cause, causing the system frequency to become smaller than the reference frequency (50 Hz).

[0038] When the system frequency becomes lower than the reference frequency (50 Hz), the UPS 100 detects this event and starts the timer 190. The timer 190 starts counting time. After starting the timer 190, the charge / discharge instruction unit 180 increases the regulating power (here, the discharge power) according to a curve that is initially steep and gradually becomes shallower as shown in the figure below. If the timer 190 exceeds a first time period (5 minutes in the example shown in the figure), it times out and outputs a timeout signal. In response to the timeout signal, the charge / discharge instruction unit 180 stops providing the regulating power. This prevents a decrease in the state of charge (SoC) of the storage battery 110.

[0039] In this embodiment, discharging power is treated as the adjustment capability, but charging power can also be treated. In this case, the adjustment capability shown in the figure below is treated as charging power, and the same processing as in the case of discharging power can be performed. In this case, when the system frequency becomes higher than the reference frequency, charging is performed only for a first time, and when the first time has elapsed, charging is stopped. This makes it possible to prevent overcharging of the storage battery 110. This operation corresponds to changing the pattern of the charging area of ​​the first charging / discharging pattern.

[0040] In this embodiment, an example of changing the pattern portion of the discharge area or the charge area of ​​the first charge / discharge pattern has been shown, but similar changes can also be applied to the second charge / discharge pattern or the third charge / discharge pattern.

[0041] (Fourth embodiment) The fourth embodiment is an embodiment in which a plurality of uninterruptible power supplies (UPS) are provided. In this embodiment, the plurality of UPS supplies adjustment power (charging power, discharging power) to the power system 300.

[0042] FIG. 11 shows an example of a power system according to the fourth embodiment. UPSs 100A and 200B are provided, and the UPSs 100A and 200B are connected in parallel to a power system 300 and are also connected in parallel to a load device 200. In the example of FIG. 11, there are two UPSs, but three or more UPSs may be used. FIG. 12 shows an example of the configuration of a power system in the case of four UPSs. UPS 200C and UPS 200D are added to the configuration of FIG. 11.

[0043] In Fig. 11 or 12, the block configuration of each UPS may be the same as that of the first to third embodiments. The following mainly describes the parts that are different from the first to third embodiments. Although the case where there are two UPSs shown in Fig. 11 will be described as an example, the processing can be expanded in the same manner to the case where there are three or more UPSs.

[0044] In this embodiment, the adjustment capability of each UPS is determined according to the priority of each UPS in addition to the deviation (frequency deviation) between the system frequency and the reference frequency. Here, an example is shown in which the first charge / discharge pattern is applied to each UPS, assuming that the charge state of each UPS is within the normal range (not less than the first threshold and not more than the second threshold). The first threshold and the second threshold may be different for each UPS. The content of the first charge / discharge pattern of each UPS is set according to the priority of each UPS. The content of each first charge / discharge pattern is determined taking into consideration the charge / discharge prediction required in advance for each UPS, and it is assumed that if the prediction accuracy is high, the power receiving state of each storage battery will basically be within the normal range (not less than the first threshold and not more than the second threshold) and the first charge / discharge pattern will be maintained. If the prediction is wrong and the charge state of at least one UPS is outside the normal range (less than the first threshold or not less than the second threshold), that UPS is switched to the second charge / discharge pattern or the third charge / discharge pattern as in the first embodiment, and the UPS whose charge state is within the normal range uses the first charge / discharge pattern without changing it. In this case, the adjustment capability of the power system 300 may not be sufficient for stable operation of the load device, but in this case, the UPS gives priority to protecting the storage battery.

[0045] FIG. 13 shows an example of a first charge / discharge pattern applied to each of UPS 100A and 200B. However, for the sake of explanation, a total charge / discharge pattern obtained by adding up the first charge / discharge patterns applied to each of UPS 100A and 200B is shown. Of UPS 100A and 200B, one UPS is designated as UPS-A, and the other UPS is designated as UPS-B. The sum of the adjustment capacity of UPS-A and the adjustment capacity of UPS-B is the adjustment capacity for the power system 300. These two UPS-A and UPS-B share the adjustment capacity at the same rate (adjustment ratio) at any frequency. In other words, UPS-A and UPS-B have the same priority, and each supplies the same adjustment capacity.

[0046] Fig. 14 shows an example of a first charge / discharge pattern applied to each of the UPS 100A and 200B, in which the UPS with a low priority (UPS-low priority) has more opportunities to supply adjustment power for frequency fluctuations than the UPS with a high priority (UPS-high priority). However, for the sake of explanation, a total charge / discharge pattern is shown as the sum of the first charge / discharge patterns applied to the UPS 100A and 200B. An example of a high priority UPS is a UPS that supplies power to infrastructure servers that are relatively affected when a server is stopped. UPS-high priority corresponds to a first uninterruptible power supply with a high priority, and UPS-low priority corresponds to a second uninterruptible power supply with a low priority.

[0047] When the system frequency is higher than the reference frequency 50Hz, the UPS-high priority does not supply regulation power (charging and discharging power is zero) in a range where the deviation is less than a predetermined value D15, and when the deviation is equal to or greater than the predetermined value D15, the UPS-high priority charges the storage battery 110 with a larger charging power as the deviation increases (however, when the deviation is greater than 50.2kZ, the charging power is constant). When the system frequency is lower than the reference frequency 50Hz, the UPS-high priority does not supply regulation power in a range where the deviation is equal to or greater than a predetermined value D16, and when the deviation is less than the predetermined value D16, the UPS-high priority discharges the storage battery 110 with a larger discharging power as the deviation decreases (however, when the deviation is less than 49.8Hz, the discharging power is constant). The range between the predetermined value D16 and less than the predetermined value D15 corresponds to the case where the deviation is within a first range with respect to the reference frequency.

[0048] The operation of UPS-low priority is as follows: when the system frequency is higher than the reference frequency 50Hz, the storage battery 110 is charged with a larger charging power as the deviation increases within a range where the deviation is less than a predetermined value D15, and the storage battery 110 is charged with a constant charging power within a range where the deviation is equal to or greater than the predetermined value D15. When the system frequency is lower than the reference frequency 50Hz, the storage battery 110 is discharged with a larger discharging power as the deviation decreases within a range where the deviation is equal to or greater than a predetermined value D16, and is discharged with a constant discharging power below the predetermined value D16.

[0049] In this way, the UPS with a lower priority operates proactively, and the opportunities for the UPS with a higher priority to provide adjustment power are reduced. By reducing the opportunities for the UPS with a higher priority to provide adjustment power, it is possible to reduce problems that may occur in the UPS with a higher priority.

[0050] The priority of each UPS described above may be explicitly set as a priority value for the UPS, or the priority may be distinguished based on other criteria. In the following, an example is shown in which the priority is set according to the type of storage battery or the user.

[0051] 15 shows an example of a first charge / discharge pattern applied to each of the UPS 100A, 200B when one of them is a UPS using a lead-acid battery (UPS-lead-acid battery) and the other is a UPS using a lithium-ion battery (UPS-LIB). For the sake of explanation, however, a total charge / discharge pattern is shown which is the sum of the first charge / discharge patterns applied to the UPS 100A, 200B. The UPS-lead-acid battery corresponds to the first uninterruptible power supply with a high priority, and the UPS (UPS-LIB) corresponds to the second uninterruptible power supply with a low priority.

[0052] When the system frequency is higher than the reference frequency 50Hz, the UPS-lead-acid battery does not supply regulating power in a range where the deviation is less than a predetermined value D17, and when the deviation is equal to or greater than the predetermined value D17, the storage battery 110 is charged with a larger charging power as the deviation increases (however, when the deviation is greater than 50.2Hz, the charging power is constant). When the system frequency is lower than the reference frequency 50Hz, the UPS-lead-acid battery does not supply regulating power in a range where the deviation is equal to or greater than a predetermined value D18, and the storage battery 110 is discharged with a larger discharging power as the deviation decreases below the predetermined value D18 (however, when the deviation is less than 49.8Hz, the discharging power is constant). The range between the predetermined value D18 and less than the predetermined value D17 corresponds to the case where the deviation is within a first range with respect to the reference frequency.

[0053] The operation of the UPS-LIB is as follows: when the system frequency is higher than the reference frequency of 50 Hz, the storage battery 110 is charged with a larger charging power as the deviation increases within a range where the deviation is less than a predetermined value D17. When the system frequency is equal to or greater than the predetermined value D17, the storage battery 110 is charged with a constant charging power. When the system frequency is lower than the reference frequency of 50 Hz, the storage battery 110 is discharged with a larger discharging power as the deviation decreases within a range where the deviation is equal to or greater than a predetermined value D18, and is discharged with a constant discharging power when the deviation is less than the predetermined value D18.

[0054] In this way, by actively operating the UPS-LIB, the opportunities for adjustment power supply from the UPS-lead-acid battery can be reduced, and deterioration of the lead-acid battery can be reduced.

[0055] FIG. 16 is a partial modification of the first charge / discharge pattern of the UPS-lead storage battery shown in FIG. 15. In the charge region, the UPS-lead storage battery charges the storage battery 110 with a constant charging power when the deviation becomes equal to or greater than a predetermined value D19. The operation in the discharge region is the same as that in FIG. 15. The first charge / discharge pattern of the UPS-LIB is the same as that in FIG. 15. In the first charge / discharge pattern of the UPS-lead storage battery, since the deterioration of a lead storage battery progresses faster when the battery is rapidly charged, the deterioration can be suppressed by suppressing the charging speed. In the example of FIG. 16, the adjustment power output from the UPS-lead storage battery is asymmetric between the discharge direction and the charge direction.

[0056] FIG. 17 shows an example of a first charge / discharge pattern applied to each of the UPS 100A and 200B when the UPS are multiple UPSs placed in a data center. However, for the sake of explanation, a total charge / discharge pattern obtained by adding up the first charge / discharge patterns applied to the UPS 100A and 200B is shown. A priority is set for each UPS user, and each first charge / discharge pattern is set so that the UPS of a user with a higher priority (UPS-user B) has fewer operating opportunities than the UPS of a user with a lower priority (UPS-user A). UPS-user B corresponds to a first uninterruptible power supply with a higher priority, and UPS-user A corresponds to a second uninterruptible power supply with a lower priority. The operation of each UPS is basically the same as in FIG. 14, but will be described below.

[0057] When the system frequency is higher than the reference frequency 50Hz, the UPS-user B does not supply regulating power in a range where the deviation is less than a predetermined value D21, and charges the storage battery 110 with a larger charging power as the deviation becomes larger when the deviation is equal to or greater than the predetermined value D21 (however, when the deviation is greater than 50.2Hz, the charging power is constant). When the system frequency is lower than the reference frequency 50Hz, the UPS-user B does not supply regulating power in a range where the deviation is equal to or greater than a predetermined value D22, and discharges the storage battery 110 with a larger discharging power as the deviation becomes smaller when the deviation is less than the predetermined value D22 (however, when the deviation is less than 49.8Hz, the discharging power is constant). The range where the deviation is equal to or greater than the predetermined value D22 and less than the predetermined value D21 corresponds to the case where the deviation is within a first range with respect to the reference frequency.

[0058] The operation of UPS-User A is as follows: when the system frequency is higher than the reference frequency 50Hz, the storage battery 110 is charged with a larger charging power as the deviation increases within a range where the deviation is less than a predetermined value D21, and the storage battery 110 is charged with a constant charging power within a range where the deviation is equal to or greater than the predetermined value D21. When the system frequency is lower than the reference frequency 50Hz, the storage battery 110 is discharged with a larger discharging power as the deviation decreases within a range where the deviation is equal to or greater than a predetermined value D22, and is discharged with a constant discharging power below the predetermined value D22.

[0059] The usage fee for the UPS may be determined according to the priority order. In this example, the usage fee for the UPS-user B with a higher priority order may be set higher than the usage fee for the UPS of a user with a lower priority order (UPS-user A). By reducing the opportunities for the UPS-user B with a higher priority order to supply adjustment power, it is possible to reduce problems that may occur in the UPS-user B with a higher priority order, and to operate the load device operated by user B more stably.

[0060] 11 and 12 described above show an example in which a plurality of UPSs are connected in parallel to one load device 200, but when there are a plurality of load devices, a configuration in which a UPS is provided for each load device is also possible.

[0061] FIG. 18 shows an example of the configuration of another power system according to this embodiment. A plurality of load devices 200A and 200B are provided, and uninterruptible power supplies (UPS) 100A and 200B are connected to them, respectively. The UPS 100A and 200B are connected in parallel to the power system 300. In addition, spare UPS 100C and 100D are provided as standby systems. If the UPS 100A or UPS 100B breaks down, the standby UPS 100C or 100D operates. For example, if the UPS 100A breaks down, the UPS 100C or UPS 100D operates in place of the UPS 100C by connecting the UPS 100C or UPS 100D to the power line between the power system 300 and the load device 200A via the spare power line 350. Similarly, if the UPS 100B breaks down, the UPS 100C or UPS 100D operates in place of the UPS 100B. The first charge / discharge pattern similar to that of FIG. 12 to FIG. 16 can be applied to such UPS 100A and UPS 100B. When at least one of UPS 100A or UPS 100B fails and the standby UPS operates, the first charge / discharge pattern can be applied to the two operating UPS including the standby UPS, as in Figs. 13 to 17. Note that, as in the embodiment of Fig. 11 or 12, not only the first charge / discharge pattern but also the second charge / discharge pattern or the third charge / discharge pattern can be applied depending on the charge state of each storage battery. Although Fig. 18 shows an example of two load devices, the same operation can be realized in the case of three or more load devices by connecting a UPS to each of them.

[0062] Fifth embodiment In the charge / discharge patterns shown in Figures 2, 4 to 6, and 13 to 17, the adjustment power changes with a constant slope (linearly) in response to changes in deviation, except for the range where the slope is zero, but the charge / discharge pattern may also change in a step-like manner.

[0063] Fig. 19 shows an example of the first charge / discharge pattern when it changes in a step-like manner. It is also possible to make the second charge / discharge pattern and the third charge / discharge pattern have shapes that change in a step-like manner. By changing in a step-like manner, there is an advantage that the number of stages of the adjustment power can be reduced.

[0064] Sixth embodiment In the first to fifth embodiments, an uninterruptible power supply (UPS) supplies adjustment power (discharging or supplying power from a storage battery) through autonomous control in response to frequency fluctuations in the power system 300. However, in the sixth embodiment, the UPS supplies adjustment power based on commands from a higher-level control system.

[0065] 20 shows an example of a power system according to the sixth embodiment. The UPS 400 does not include a voltage sensor 150 and a frequency measurement unit 160. A charge / discharge amount calculation unit 170 is connected to an energy management system (EMS) 800 by wire or wirelessly.

[0066] A command for adjustment capability is transmitted to EMS 800 from central load dispatching center 500, which is a higher-level control system, via an aggregator coordination (AC) system 600 of an aggregator (a specified wholesale supplier) and a resource aggregator (RC) system 700. EMS 800 may be placed in the same facility (e.g., a data center) as UPS 400. EMS 800 issues a command for adjustment capability to UPS 400. Based on the command from EMS 800, charge / discharge amount calculation unit 170 sends an instruction for adjustment capability (charge / discharge instruction) to charge / discharge instruction unit 180.

[0067] As described above, according to this embodiment, the UPS 400 can be made to output regulation power in response to a command from a higher-level system. If a frequency fluctuation can be detected faster in a higher-level system than the UPS 400, regulation power can be supplied to the power system 300 more quickly, and the load device 200 can be operated more stably. Furthermore, since there is no need to provide the voltage sensor 150 and the frequency measurement unit 160 in the UPS 400, the configuration of the UPS 400 can be simplified.

[0068] The present invention is not limited to the above-described embodiment as it is, and the components can be modified and embodied in the implementation stage without departing from the gist of the invention. In addition, various inventions can be formed by appropriately combining the multiple components disclosed in the above-described embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, components from different embodiments may be appropriately combined.

[0069] This embodiment can also have the following configuration. [Item 1] An uninterruptible power supply that can be connected to a power line through which power is supplied from a power system to a load device, A rechargeable storage battery; A monitoring unit that monitors a charging state of the storage battery; a control unit that controls charging and discharging from the storage battery to the power line based on a difference between a first frequency that is a frequency of the power system and a second frequency that is a reference for the power system and based on a state of charge of the storage battery; An uninterruptible power supply equipped with [Item 2] The control unit selects a charge / discharge pattern from among a plurality of charge / discharge patterns in which the difference is associated with a charge / discharge power value to be charged / discharged to the power line in accordance with a charge state of the storage battery, and controls charging / discharging of the storage battery based on the selected charge / discharge pattern and the difference. Item 1. An uninterruptible power supply according to item 1. [Item 3] The control unit selects a first charging / discharging pattern when the charging state is equal to or greater than the first threshold, and selects a second charging / discharging pattern when the charging state is less than the first threshold. Item 2. An uninterruptible power supply according to item 2. [Item 4] The first charge / discharge pattern is: If the difference is greater than a first predetermined value, a larger charging power is set as the difference is greater; When the difference is smaller than the first predetermined value, a larger discharge power is set as the difference is smaller. The second charge / discharge pattern is: When the difference is greater than a second predetermined value, a larger charging power is set as the difference is greater; When the difference is smaller than the second predetermined value, a larger discharge power value is set as the difference is smaller, The first predetermined value is greater than the second predetermined value. Item 3. An uninterruptible power supply according to item 3. [Item 5] The second charge / discharge pattern is: If the difference is greater than a third predetermined value, a larger charging power is set as the difference is greater; When the difference is smaller than the third predetermined value, the discharge power is set to zero. Item 3. An uninterruptible power supply according to item 3. [Item 6] The control unit selects a third charge / discharge pattern when the state of charge is equal to or greater than a second threshold, and the second threshold is greater than the first threshold. 6. The uninterruptible power supply according to any one of items 3 to 5. [Item 7] The first charge / discharge pattern is: If the difference is greater than a first predetermined value, a larger charging power is set as the difference is greater; When the difference is smaller than the first predetermined value, a larger discharge power is set as the difference is smaller. The third charge / discharge pattern is: If the difference is greater than a fourth predetermined value, a larger charging power is set as the difference is greater; When the difference is smaller than the fourth predetermined value, a larger discharge power value is set as the difference is smaller, The fourth predetermined value is greater than the first predetermined value. Item 6. An uninterruptible power supply according to item 6. [Item 8] The third charge / discharge pattern is: When the difference is greater than a fifth predetermined value, the charging power is set to zero. When the difference is smaller than a fifth predetermined value, the smaller the difference is, the larger the discharge power is set. Item 6. An uninterruptible power supply according to item 6. [Item 9] The state of charge is a ratio of the amount of charge in the storage battery to the capacity of the storage battery. The uninterruptible power supply according to any one of items 3 to 8. [Item 10] a timer that starts counting a first time when the frequency of the power grid falls below a threshold; The control unit discharges the storage battery during the first time period, When the timer detects that the first time period has elapsed, an AC / DC converter provided between the power system and the load device is stopped, and discharging of the storage battery is stopped. 10. An uninterruptible power supply according to any one of items 1 to 9. [Item 11] A first uninterruptible power supply device which is the uninterruptible power supply device according to item 1, and a second uninterruptible power supply device which is the uninterruptible power supply device according to item 1, the priority of the first uninterruptible power supply is higher than the priority of the second uninterruptible power supply; When the difference between the first frequency and the second frequency is within a first range with respect to the second frequency, the second uninterruptible power supply is charged and discharged with priority over the first uninterruptible power supply. Power system. [Item 12] When the difference is within the first range, the first uninterruptible power supply is not charged or discharged. Item 12. The power system according to item 11. [Item 13] The storage battery of the first uninterruptible power supply is a first type of storage battery, and the storage battery of the second uninterruptible power supply is a second type of storage battery different from the first type. 13. The power system according to item 11 or 12. [Item 14] A control device for controlling an uninterruptible power supply device connectable to a power line through which power is supplied from a power system to a load device, A monitoring unit that monitors a charging state of a storage battery in the uninterruptible power supply; a control unit that controls charging and discharging from the storage battery of the uninterruptible power supply to the power line based on a difference between a first frequency that is a frequency of the power system and a second frequency that is a reference for the power system and based on a charging state of the storage battery; A control device comprising: [Item 15] A control method for controlling an uninterruptible power supply device connectable to a power line through which power is supplied from a power system to a load device, comprising: Obtaining a state of charge of a chargeable / dischargeable storage battery in the uninterruptible power supply; The charging and discharging from the storage battery of the uninterruptible power supply device to the power line is controlled based on a difference between a first frequency which is a frequency of the power system and a second frequency which is a reference for the power system, and based on a charging state of the storage battery. Control methods. [Explanation of symbols]

[0070] 100 Uninterruptible power supply (UPS) 100A uninterruptible power supply (UPS) 110 Battery 120 Adjustment section 121 AC / DC conversion section 122 DC / AC conversion section 130 DC / DC conversion section 135 Control device 140 Battery monitoring unit 140 Components 150 Voltage Sensor 160 Frequency measurement section 170 Components 170 Charge / discharge amount calculation section 170 Charging and discharging energy calculation section 180 Charge / discharge instruction section 190 Timer 200 load device 200A load device 300 Power system 350 Reserve Power Line 500 Central Power Dispatch Center 600 System 700 System 800 Energy Management System (EMS)

Claims

1. An uninterruptible power supply that can be connected to a power line through which power is supplied from a power system to a load device, A rechargeable storage battery; A monitoring unit that monitors a charging state of the storage battery; a control unit that controls charging and discharging from the storage battery to the power line based on a difference between a first frequency that is a frequency of the power system and a second frequency that is a reference for the power system and based on a state of charge of the storage battery; An uninterruptible power supply equipped with

2. The control unit selects a charge / discharge pattern from among a plurality of charge / discharge patterns in which the difference is associated with a charge / discharge power value to be charged / discharged to the power line in accordance with a charge state of the storage battery, and controls charging / discharging of the storage battery based on the selected charge / discharge pattern and the difference.

2. The uninterruptible power supply of claim 1.

3. The control unit selects a first charging / discharging pattern when the charging state is equal to or greater than the first threshold, and selects a second charging / discharging pattern when the charging state is less than the first threshold.

3. The uninterruptible power supply according to claim 2.

4. The first charge / discharge pattern is: When the difference is greater than a first predetermined value, a larger charging power is set as the difference is greater; When the difference is smaller than the first predetermined value, a larger discharge power is set as the difference is smaller. The second charge / discharge pattern is: When the difference is greater than a second predetermined value, a larger charging power is set as the difference is greater; When the difference is smaller than the second predetermined value, a larger discharge power value is set as the difference is smaller, The first predetermined value is greater than the second predetermined value.

4. An uninterruptible power supply according to claim 3.

5. The second charge / discharge pattern is: When the difference is greater than a third predetermined value, a larger charging power is set as the difference is greater; When the difference is smaller than the third predetermined value, the discharge power is set to zero.

4. An uninterruptible power supply according to claim 3.

6. The control unit selects a third charging / discharging pattern when the state of charge is equal to or greater than a second threshold, and the second threshold is greater than the first threshold.

4. An uninterruptible power supply according to claim 3.

7. The first charge / discharge pattern is: When the difference is greater than a first predetermined value, a larger charging power is set as the difference is greater; When the difference is smaller than the first predetermined value, a larger discharge power is set as the difference is smaller. The third charge / discharge pattern is: If the difference is greater than a fourth predetermined value, a larger charging power is set as the difference is greater; When the difference is smaller than the fourth predetermined value, a larger discharge power value is set as the difference is smaller, The fourth predetermined value is greater than the first predetermined value.

7. An uninterruptible power supply according to claim 6.

8. The third charge / discharge pattern is: When the difference is greater than a fifth predetermined value, the charging power is set to zero. When the difference is smaller than a fifth predetermined value, the smaller the difference is, the larger the discharge power is set.

7. An uninterruptible power supply according to claim 6.

9. The state of charge is a ratio of the amount of charge in the storage battery to the capacity of the storage battery.

4. An uninterruptible power supply according to claim 3.

10. a timer that starts counting a first time when the frequency of the power grid falls below a threshold; The control unit discharges the storage battery during the first time period, When the timer detects that the first time has elapsed, an AC / DC converter provided between the power system and the load device is stopped, and discharging of the storage battery is stopped.

2. The uninterruptible power supply of claim 1.

11. A first uninterruptible power supply device which is the uninterruptible power supply device according to claim 1 and a second uninterruptible power supply device which is the uninterruptible power supply device according to claim 1, The priority of the first uninterruptible power supply is higher than the priority of the second uninterruptible power supply; When the difference between the first frequency and the second frequency is within a first range with respect to the second frequency, the second uninterruptible power supply is charged and discharged with priority over the first uninterruptible power supply. Power system.

12. When the difference is within the first range, the first uninterruptible power supply is not charged or discharged.

12. The power system of claim 11.

13. The storage battery of the first uninterruptible power supply is a first type of storage battery, and the storage battery of the second uninterruptible power supply is a second type of storage battery different from the first type.

12. The power system of claim 11.

14. A control device for controlling an uninterruptible power supply device connectable to a power line through which power is supplied from a power system to a load device, A monitoring unit that monitors a charging state of a storage battery in the uninterruptible power supply; a control unit that controls charging and discharging from the storage battery of the uninterruptible power supply to the power line based on a difference between a first frequency that is a frequency of the power system and a second frequency that is a reference for the power system and based on a charging state of the storage battery; A control device comprising:

15. A control method for controlling an uninterruptible power supply device connectable to a power line through which power is supplied from a power system to a load device, comprising: Obtaining a state of charge of a chargeable / dischargeable storage battery in the uninterruptible power supply; The charging and discharging from the storage battery of the uninterruptible power supply device to the power line is controlled based on a difference between a first frequency which is a frequency of the power system and a second frequency which is a reference for the power system, and based on a charging state of the storage battery. Control methods.

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