Power system

Abstract

To provide a power system which issues an alarm only when the alarm is really necessary.SOLUTION: A power system 10 comprises a plurality of loads 291 to 294 interconnected with a power system, a current sensor CT provided at an interconnection point, a battery 22, a storage battery power conditioner 21, and a main control device 30. The storage battery power conditioner 21 converts AC power supplied from the power system into DC power to charge the battery 22 and converts DC power discharged from the battery 22 into AC power to supply it to the plurality of loads 291 to 294. The main control device 30 supplies power from the battery 22 to the plurality of loads 291 to 294 by discharge through the storage battery power conditioner 21 when it is determined that a purchased power amount in a predetermined period exceeds an alert activation threshold. The main control device 30 further activates an alert to a communication terminal 90 when it is determined that the purchased power amount in the predetermined period which decreases by the discharge still exceeds the alert activation threshold.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This relates to a power system that stores electricity during times when demand on the commercial power grid is not tight and discharges it during times when load power consumption is close to its peak, thereby reducing the amount of electricity purchased from the commercial power grid within a specified period of time. [Background technology]

[0002] A power load estimation device is described in Patent Document 1. The power load estimation device in Patent Document 1 estimates the value of future active power of a device based on electrical physical quantities of an electrical system that supplies power to the device.

[0003] Furthermore, conventionally, there is known a power system that issues a warning to a user when the estimated future active power (power consumption) is predicted to exceed a predetermined electricity rate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-059126 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the case of a power system equipped with solar panels and storage batteries, even if the threshold is exceeded momentarily, the threshold may not ultimately be exceeded if the amount of solar radiation increases and the amount of solar power generated increases, or if the storage battery capacity is sufficient and discharge assistance from the solar panels and storage batteries is provided.

[0006] In this case, the user may be notified of an unnecessary warning, which may impair the user's usability.

[0007] Therefore, an object of the present invention is to provide a power system that can issue a warning only when truly necessary, even when there is an auxiliary power supply source separate from the commercial power system, such as a solar panel or a storage battery. [Means for solving the problem]

[0008] A power system according to one embodiment of the present invention includes a plurality of loads connected to a power grid, a current sensor provided at a connection point between the power grid and the plurality of loads, a storage battery, a storage battery power conditioner, and a control unit. The storage battery power conditioner is connected to the power grid and converts AC power supplied from the power grid into DC power to charge the storage battery, and converts DC power discharged from the storage battery into AC power to supply to the plurality of loads. The control unit controls charging and discharging of the storage battery based on the amount of power purchased from the power grid calculated from the value of the current sensor.

[0009] When the control unit determines that the amount of purchased electricity within a predetermined period exceeds the alert threshold, the control unit controls the storage battery to supply electricity to the multiple loads by discharging through the storage battery power conditioner. When the control unit determines that the amount of purchased electricity within the predetermined period that has decreased due to the discharge still exceeds the alert threshold, the control unit issues an alert.

[0010] With this configuration, an alert can be issued (a warning issued) only when it is determined that the amount of purchased electricity will exceed the contracted amount of electricity, taking into account discharge assistance from the storage battery.

[0011] A power system according to one embodiment of the present invention includes a plurality of loads connected to a power grid, a current sensor provided at a connection point between the power grid and the plurality of loads, a storage battery, a solar panel, a storage battery power conditioner, a PV power conditioner, and a control unit. The storage battery power conditioner is connected to the power grid and converts AC power supplied from the power grid into DC power to charge the storage battery, and converts DC power discharged from the storage battery into AC power to supply to the plurality of loads. The PV power conditioner is connected to the power grid and converts DC power discharged from the solar panel into AC power to supply to the plurality of loads. The control unit controls charging and discharging of the storage battery based on the amount of power purchased from the power grid calculated from the value of the current sensor and the amount of power generated by the solar panel.

[0012] When the control unit determines that the amount of purchased electricity within a predetermined period, including the amount of electricity generated by the solar panels, exceeds the alert threshold, the control unit controls the storage battery to supply electricity to the multiple loads by discharging through the storage battery power conditioner. When the control unit further determines that the amount of purchased electricity within the predetermined period, reduced by the discharge and including the amount of electricity generated by the solar panels, still exceeds the alert threshold, the control unit issues an alert.

[0013] With this configuration, an alert (warning) can be issued only when it is determined that the amount of purchased electricity exceeds the contracted amount of electricity, taking into account the amount of electricity discharged from the solar panels and the discharge assistance from the storage battery. [Effects of the Invention]

[0014] According to this invention, even if there is an auxiliary power supply source separate from the commercial power system, such as a solar panel or a storage battery, a warning can be issued only when it is truly necessary. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a functional block diagram of a power system according to a first embodiment of the present invention. [Figure 2]FIG. 2 is a graph showing an example of transition of each amount of power in a first mode of the alert issuance process using the first embodiment. [Figure 3] FIG. 3 is a graph showing an example of transition of each amount of power in a first mode of the alert issuance process using the first embodiment. [Figure 4] FIG. 4 is a flowchart showing an example of a first aspect of the alert issuance process using the first embodiment. [Figure 5] FIG. 5 is a graph showing an example of transition of each amount of power in the second mode of the alert issuance process using the first embodiment. [Figure 6] FIG. 6 is a graph showing an example of transition of each amount of power in the third mode of the alert issuance process using the first embodiment. [Figure 7] FIG. 7 is a flowchart showing an example of a third aspect of the alert issuance process using the first embodiment. [Figure 8] FIG. 8 is a functional block diagram of a power system according to the second embodiment of the present invention. [Figure 9] FIG. 9 is a graph showing an example of transition of each amount of power in the fourth mode of the alert issuance process using the second embodiment. [Figure 10] FIG. 10 is a flowchart showing an example of a fourth aspect of the alert issuance process using the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] [First embodiment] A power system according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a functional block diagram of the power system according to the first embodiment of the present invention.

[0017] 1, the power system 10 includes a storage battery power conditioner (storage battery PCS) 21, a battery 22, a power transmission line 200, a plurality of loads 291-294 (load 291, load 292, load 293, load 294), a plurality of switches S1-S4 (switch S1, switch S2, switch S3, switch S4), a grid interconnection relay RL1, a current sensor CT, and a main control device 30. Note that the number of loads and the number of switches are not limited to four.

[0018] The power facility 20 is composed of a storage battery power conditioner 21, a battery 22, a power transmission line 200, a plurality of loads 291-294 (load 291, load 292, load 293, load 294), a plurality of switches S1-S4 (switch S1, switch S2, switch S3, switch S4), a grid interconnection relay RL1, and a current sensor CT.

[0019] A commercial power system is connected to one end of power transmission line 200. The other end of power transmission line 200 is connected to battery power conditioner 21 via a grid interconnection relay RL1.

[0020] The battery power conditioner 21 includes a PCS control circuit 210, an inverter 211, and a bidirectional DC-DC converter 212. The inverter 211 and the bidirectional DC-DC converter 212 are connected to each other. The inverter 211 is connected to a power transmission line 200. The bidirectional DC-DC converter 212 is connected to the battery 22. The PCS control circuit 210 is connected to the inverter 211 and the bidirectional DC-DC converter 212, and controls the operations of the inverter 211 and the bidirectional DC-DC converter 212.

[0021] A plurality of loads 291-294 are respectively connected to the power transmission line 200 through a plurality of switches S1-S4. Specifically, the load 291 is connected to the power transmission line 200 through the switch S1, and the load 292 is connected to the power transmission line 200 through the switch S2. The load 293 is connected to the power transmission line 200 through the switch S3, and the load 294 is connected to the power transmission line 200 through the switch S4.

[0022] The current sensor CT is arranged at a predetermined point (connection point) between the commercial power system and the connection portion between the plurality of loads 291-294.

[0023] The main controller 30 is connected to the current sensor CT. The main controller 30 is connected to the PCS control circuit 210, each of the multiple switches S1-S4, and the grid interconnection relay RL1.

[0024] At least electric power (purchased power) from the commercial power grid is supplied to the plurality of loads 291-294. At this time, main control device 30 controls the amount of power purchased from the commercial power grid based on the current value measured by current sensor CT so that the amount of power purchased from the commercial power grid does not exceed the contracted amount of power.

[0025] More specifically, when the amount of power (power consumption) supplied to the multiple loads 291-294 based on the current value of the current sensor CT is lower than the contracted amount of power, the main control device 30 does not assist discharging from the battery 22 and supplies power to the multiple loads 291-294 from the commercial power system.

[0026] If battery 22 has a chargeable capacity, main control device 30 instructs PCS control circuit 210 to charge battery 22. When PCS control circuit 210 receives a charge instruction from main control device 30, it converts AC power from the commercial power system into DC power using inverter 211, converts this DC power into DC power for charging battery 22 using bidirectional DC-DC converter 212, and supplies it to battery 22. In this way, battery 22 is charged.

[0027] On the other hand, when the amount of power (power consumption) supplied to the plurality of loads 291-294 is likely to be higher than the contracted amount of power based on the current value measured by the current sensor CT, the main control device 30 supplies power to the plurality of loads 291-294 from the commercial power system while assisting discharge from the battery 22. The main control device 30 instructs the PCS control circuit 210 (discharge assist instruction) the amount of power to be discharged from the battery 22 so that the amount of purchased power does not exceed the contracted amount of power.

[0028] When PCS control circuit 210 receives a discharge command from main control device 30, it converts the discharge power from battery 22 into DC power of a predetermined voltage level using bidirectional DC-DC converter 212, converts this DC power into AC power using inverter 211, and supplies it to multiple loads 291-294. In this way, power system 10 uses discharge assistance by battery 22 to supply the necessary and sufficient amount of power to multiple loads 291-294, while preventing the amount of purchased power from exceeding the contracted amount of power.

[0029] In addition, if the loads of multiple loads 291-294 suddenly decrease, for example, and if it is determined that reverse power flow to the commercial power system is likely to occur based on the current value of the current sensor CT, the main control device 30 will cut off (open) the grid interconnection relay RL1 and disconnect the battery power conditioner 21 from the commercial power system.

[0030] In such a configuration, the power system 10 performs the following alert issuance process. In general, the alert issuance process is a process in which, when the main control device 30 determines that the amount of purchased power within a predetermined period (e.g., 30 minutes) exceeds the alert issuance threshold, an alert is issued to, for example, the manager of the power facility 20.

[0031] In this case, in the power system 10, if the main control device 30 determines that the amount of purchased electricity exceeds the alert issuance threshold, it causes the battery 22 to supply electricity to the multiple loads 291-294 by discharging through the storage battery power conditioner 21, and if it determines that the amount of purchased electricity within a specified period that is reduced by discharging still exceeds the alert issuance threshold, it issues an alert.

[0032] Several aspects will be specifically described below.

[0033] (First aspect) The first aspect shows the alert issuance process when the cumulative load power consumption exceeds the alert issuance threshold line during a predetermined period. Figures 2 and 3 are graphs showing an example of the transition of each power amount in the first aspect of the alert issuance process using the first embodiment. Figure 2 shows a case where there is no load fluctuation after a certain alert issuance determination time, and the purchased power amount does not exceed the alert issuance threshold line over a predetermined period. Figure 3 shows a case where there is a load fluctuation after a certain alert issuance determination time, and the purchased power amount exceeds the alert issuance threshold line within the predetermined period.

[0034] 2 and 3, the solid line indicates the cumulative load power consumption, the two-dot chain line indicates the demand boundary, the one-dot chain line indicates the alert issuance threshold line, and the dotted line indicates the amount of purchased power with discharge assistance from the battery 22. The dashed line indicates the predicted amount of power based on the cumulative power consumption.

[0035] The cumulative load power consumption is the cumulative value of the amount of power consumed by the loads 291-294 (the amount of power supplied from the commercial power grid) from the start time of one cycle (for example, 30 minutes) for determination to the measurement time.

[0036] The demand boundary is set based on the contracted energy amount, and is set by the cumulative energy consumption for each hour when the energy consumption increases at a constant rate during a specified period. For example, in the case of Figure 2, the contracted energy amount is 1500 kWh and the specified period is 30 minutes, so if time 2 is x and the energy amount is y, the demand boundary is set as y = 50x.

[0037] The alert threshold line is set based on the demand boundary line and the false alarm prevention margin, and is set so that the amount of power is lower than the demand boundary line at any time within a specified time period (excluding 0 minutes). For example, in the case of Figure 2, the demand boundary line is set to y=50x, and the alert threshold line is set to y=45x.

[0038] The amount of purchased power with discharge assistance is the cumulative amount of purchased power when discharge assistance from the battery 22 is performed.

[0039] For example, in the cases of Figures 2 and 3, the cumulative load power consumption is lower than the alert threshold line until time t1 (for example, 17 minutes from the start of the specified time). However, at time t1, it becomes the same as the alert threshold line, and the rate of change of the cumulative load power consumption just before time t1 is greater than the rate of change of the alert threshold line. In this case, after time t1, the cumulative load power consumption becomes greater than the alert threshold line, and furthermore, by the end of the specified period, the cumulative load power consumption becomes greater than the demand boundary line.

[0040] Main control device 30 detects that the cumulative load power consumption has exceeded the alert issuance threshold line, and performs discharge assist from battery 22 via storage battery power conditioner 21. At this time, main control device 30 performs discharge assist control so that the amount of power obtained by subtracting the discharge assist power amount of battery 22 from the power consumption amount, i.e., the purchased power amount, does not exceed the alert issuance threshold line during a predetermined period.

[0041] By this control, if the amount of purchased power falls below the alert issuance threshold line for a predetermined period of time, as shown in Figure 2, the main control device 30 will not issue an alert. This allows the power system 10 to prevent the amount of purchased power from exceeding the contracted amount of power, and also to prevent unnecessary alerts from being issued.

[0042] On the other hand, as shown in Fig. 3, if the power consumption of the multiple loads 291-294 increases after time t1, the slope of the dotted line becomes steeper. In this case, for example, at time t2 in Fig. 3, the amount of purchased power may exceed the alert threshold line even with discharge assistance. The main control device 30 predicts the purchased power with discharge assistance over a predetermined period of time based on the amount of discharge assistance power from the battery 22 and the power consumption of the multiple loads 291-294.

[0043] The main control device 30 issues an alert if the amount of power consumed minus the amount of discharge assist power of the battery 22, i.e., the amount of purchased power, is about to exceed the alert threshold line at a time during a specified period, or if the amount of purchased power exceeds the alert threshold line, as at time t2 in Figure 3.

[0044] As a specific method of issuing an alert, for example, the main control device 30 has a communication function and issues an alert to the communication terminal 90 held by the administrator. Note that although the case where the amount of power consumed by the plurality of loads 291-294 increases has been shown here, similar processing can also be performed when, for example, the amount of stored power in the battery 22 decreases faster than predicted and the amount of purchased power increases.

[0045] As described above, even when the battery 22 is present, the power system 10 can issue an alert (issue a warning) only when it is truly necessary.

[0046] When an alert is issued, if an instruction to disconnect at least one of the multiple loads 291-294 is received from the administrator's communication terminal 90, the main control device 30 receives this instruction. The main control device 30 controls the switches connected to the instructed loads to disconnect them from the power transmission line 200. For example, if an instruction to disconnect load 291 is received, the main control device 30 controls disconnection from the power transmission line 200 using switch S1. This allows the power system 10 to prevent the amount of purchased power from exceeding the contracted amount of power.

[0047] In order to realize such control, the power system 10 performs, for example, the processing shown in Fig. 4. Fig. 4 is a flowchart showing an example of a first aspect of the alert issuance processing using the first embodiment.

[0048] Main control device 30 measures the cumulative load power consumption at predetermined time intervals (for example, one minute intervals) while monitoring the current value of current sensor CT (S11).

[0049] The main control device 30 stores an alert threshold (alert issuance threshold line). If the cumulative load power consumption exceeds the alert threshold (S12: YES), the main control device 30 predicts the future amount of purchased power with discharge assistance from the battery 22 (S13). If the cumulative load power consumption does not exceed the alert threshold (S12: NO), the main control device 30 does not perform discharge assistance from the battery 22 (S120) and continues measuring the cumulative load power consumption.

[0050] If the amount of purchased energy exceeds the alert threshold during the predetermined period (within 30 minutes of the end of the period) (S14: YES), the main control device 30 issues an alert (S15). If the amount of purchased energy does not exceed the alert threshold during the predetermined period (within 30 minutes of the end of the period) (S14: NO), the main control device 30 does not issue an alert.

[0051] (Second aspect) The second aspect is an alert issuance process when the cumulative load power consumption exceeds the alert issuance threshold line from the beginning of a predetermined period. Figure 5 is a graph showing an example of the transition of each power amount in the second aspect of the alert issuance process using the first embodiment. Note that the detailed process of the second aspect that is the same as the first aspect will not be described again.

[0052] 5, at the beginning of a predetermined period, the power consumption of multiple loads 291-294 exceeds the alert issuance threshold. Main control device 30 detects this and assists discharge from battery 22. At this time, main control device 30 performs discharge assist control so that the amount of power obtained by subtracting the discharge assist power amount of battery 22 from the power consumption amount, i.e., the purchased power amount, does not exceed the alert issuance threshold line during the predetermined period.

[0053] As a result of this control, if the amount of purchased power falls below the demand boundary line for a predetermined period of time, as shown in FIG. 5, main control device 30 will not issue an alert.

[0054] On the other hand, although not shown in Figure 5, the main control device 30 issues an alert if the amount of electricity consumed minus the discharge assist electricity amount of the battery 22, i.e., the amount of purchased electricity, is likely to exceed the alert issuance threshold line during a specified period.

[0055] As described above, even when the battery 22 is present, the power system 10 can issue an alert (issue a warning) only when it is truly necessary.

[0056] (Third aspect) The third aspect is an alert issuance process in which a first time period is set in which a decision on whether to issue an alert is not made for a predetermined length of time from the start time of a predetermined period. Figure 6 is a graph showing an example of the transition of each power amount in the third aspect of the alert issuance process using the first embodiment. Note that a description of the same parts of the detailed process of the third aspect as those of the first aspect will be omitted.

[0057] 6, in the third embodiment, the main control device 30 does not determine whether to issue an alert during a first time period that is a predetermined length of time (the first half of the predetermined period) from the start of the predetermined period (e.g., 30 minutes). The main control device 30 determines whether to issue an alert during a second time period within the predetermined period after the first time period has elapsed, as in the above embodiment.

[0058] This is because, in the first half of the predetermined period, the cumulative power consumption (cumulative purchased power) almost never exceeds the alert issuance threshold line, and therefore omitting this step will almost never result in a false determination of whether to issue an alert.

[0059] For example, main control device 30 does not measure the cumulative power consumption during the first time period. At the beginning of the second time period after the first time period has elapsed, main control device 30 acquires the current value of current sensor CT and estimates the cumulative power consumption from the current value, assuming that the power consumption of multiple loads 291-294 up to that point has been constant.

[0060] Thereafter, the main control device 30 performs the same processing as in the second or first aspect described above to determine whether to issue an alert.

[0061] This allows the power system 10 to issue an alert (notify a warning) only when it is truly necessary, even when the battery 22 is present. Furthermore, in the third aspect, the main control device 30 does not consume power in determining whether to issue an alert during the first time period, thereby reducing power consumption.

[0062] Note that main control device 30 may only acquire the current value of the current sensor during the first time period. In this case, main control device 30 can estimate the cumulative power consumption with high accuracy at the beginning of the second time period.

[0063] In order to realize such control, the power system 10 performs, for example, the processing shown in Fig. 7. Fig. 7 is a flowchart showing an example of a third aspect of the alert issuance processing using the first embodiment.

[0064] Main control device 30 does not make an alert determination until the start time of the alert determination (end of the first time slot) (S31: NO), and remains in a standby state.

[0065] When the start time of the alert determination (end of the first time period) arrives (S31: YES), the main control device 30 estimates the cumulative load power consumption during the first time period, for example, based on the current value of the current sensor CT at that time (S32).

[0066] If the cumulative load power consumption exceeds the alert threshold (S33: YES), the main control device 30 predicts the future amount of purchased power (S34) with discharge assistance by the battery 22. If the cumulative load power consumption does not exceed the alert threshold (S33: NO), the main control device 30 does not perform discharge assistance by the battery 22 (S331) and predicts the future cumulative load power consumption (S332).

[0067] If the amount of purchased energy exceeds the alert threshold during the predetermined period (within 30 minutes of the end of the period) (S35: YES), the main control device 30 issues an alert (S36). If the amount of purchased energy does not exceed the alert threshold during the predetermined period (within 30 minutes of the end of the period) (S35: NO), the main control device 30 does not issue an alert.

[0068] [Second embodiment] A power system according to a second embodiment of the present invention will be described with reference to the drawing. Fig. 8 is a functional block diagram of the power system according to the second embodiment of the present invention.

[0069] As shown in Fig. 8, the power system 10A according to the second embodiment differs from the power system 10 according to the first embodiment in that it can also perform discharge assistance by the solar panel 24. The power system 10A also differs from the power system 10 in that it determines whether to issue an alert after taking into account the discharge assistance by the solar panel 24. Other configurations and processes of the power system 10A are similar to those of the power system 10, and therefore, below, a description of similar parts will be omitted and only the differences will be described.

[0070] As shown in FIG. 8, the power system 10 includes a battery power conditioner (battery PCS) 21, a battery 22, a PV power conditioner (PVPCS) 23, a solar panel 24, a power transmission line 200, a plurality of loads 291-294 (load 291, load 292, load 293, load 294), a plurality of switches S1-S4 (switch S1, switch S2, switch S3, switch S4), a grid interconnection relay RL1, a grid interconnection relay RL2, a current sensor CT, and a main control device 30.

[0071] The power facility 20 is composed of a storage battery power conditioner 21, a battery 22, a power transmission line 200, a plurality of loads 291-294 (load 291, load 292, load 293, load 294), a plurality of switches S1-S4 (switch S1, switch S2, switch S3, switch S4), a grid interconnection relay RL1, a grid interconnection relay RL2, and a current sensor CT.

[0072] The PV power conditioner 23 includes a PCS control circuit 230, an inverter 231, and a PV converter 232. The inverter 231 and the PV converter 232 are connected to each other. The inverter 231 is connected to a power transmission line 200. The PV converter 232 is connected to the solar panel 24. The PCS control circuit 230 is connected to the inverter 231 and the PV converter 232, and controls the operations of the inverter 231 and the PV converter 232.

[0073] Based on a discharge command from main control device 30, PCS control circuit 230 converts the discharge power from solar panel 24 into DC power of a predetermined voltage level using PV converter 232, converts this DC power into AC power using inverter 211, and supplies it to multiple loads 291-294. In this way, power system 10A supplies power to multiple loads 291-294 using discharge assistance provided by power generation by solar panel 24, thereby reducing the amount of power purchased.

[0074] If, for example, the loads of the multiple loads 291-294 suddenly decrease or the amount of power generated by the solar panel 24 suddenly increases, and if it is determined based on the current value of the current sensor CT that a reverse power flow to the commercial power grid is likely to occur, the main control device 30 instructs the PV power conditioner 23 to reduce the amount of power generated by the solar panel 24. In response to this instruction, the PV power conditioner 23 reduces the amount of power generated by the solar panel 24 to a level that does not cause a reverse power flow. Alternatively, the main control device 30 shuts off (opens) the grid interconnection relay RL2, thereby disconnecting the storage battery power conditioner 21 from the commercial power grid.

[0075] In this configuration, the power system 10A performs the following alert issuing process.

[0076] Generally speaking, in power system 10A, when main control device 30 determines that the amount of purchased power within a predetermined period, including the amount of power generated by solar panels 24, exceeds the alert issuance threshold, main control device 30 causes battery 22 to supply power by discharging to multiple loads 291-294 via storage battery power conditioner 21. Furthermore, when main control device 30 determines that the amount of purchased power within a predetermined period, reduced by discharging from battery 22, still exceeds the alert issuance threshold, including the amount of power generated by solar panels 24, main control device 30 issues an alert.

[0077] A specific embodiment will be described below.

[0078] (Fourth aspect) The fourth aspect shows an alert issuance process when the cumulative load power consumption exceeds the alert issuance threshold line, taking into account the amount of power generated (amount of discharged power) of the solar panel 24. Fig. 9 is a graph showing an example of the transition of each power amount in the fourth aspect of the alert issuance process using the second embodiment. In Fig. 9, the long dashed line represents the cumulative PV power generation amount (cumulative photovoltaic power generation amount). The cumulative PV power generation amount is the cumulative value of the power generation amount of the solar panel 24 from the start time of one cycle (e.g., 30 minutes) for which determination is made to the measurement time.

[0079] 9, if there is no discharge assistance by power generation from the solar panel 24, the cumulative load power consumption is higher than the alert threshold line. However, if discharge assistance by power generation from the solar panel 24 is performed, the purchased power amount falls below the alert threshold line. In this case, the main control device 30 does not perform discharge assistance by the battery 22.

[0080] Here, for example, at time taS in Figure 9, if the amount of power generated by solar panel 24 decreases, the amount of purchased power increases and exceeds the alert threshold line. Main control device 30 detects this and performs discharge assistance from battery 22 via storage battery power conditioner 21. At this time, main control device 30 performs discharge assistance control so that the amount of power obtained by subtracting the discharge assistance power amount of battery 22 from the amount of power consumed, i.e., the amount of purchased power, does not exceed the alert threshold line during a predetermined period.

[0081] By this control, if the amount of purchased power remains below the alert issuance threshold line for a predetermined period of time, as shown in Figure 9, main control device 30 will not issue an alert. Thus, power system 10A can prevent the amount of purchased power from exceeding the contracted amount of power and can also prevent unnecessary alerts from being issued.

[0082] Here, when main control device 30 detects an increase in the amount of power generated by solar panel 24 at time taE, it suppresses the amount of assisting discharge power of battery 22. At this time, main control device 30 suppresses the amount of assisting discharge power of battery 22 so that the amount of purchased power does not exceed the alert issuance threshold line during the specified period. This makes it possible to conserve the stored power of battery 22 while suppressing false alerts.

[0083] On the other hand, although not shown in Figure 9, if the amount of purchased electricity is likely to exceed the alert threshold line even after adding discharge assistance from the solar panel 24 and discharge assistance from the battery 22, the main control device 30 will issue an alert.

[0084] As described above, even when the solar panel 24 and the battery 22 are present, the power system 10A can issue an alert (issue a warning) only when it is truly necessary.

[0085] In order to realize such control, the power system 10A performs, for example, the processing shown in Fig. 10. Fig. 10 is a flowchart showing an example of a fourth aspect of the alert issuance processing using the second embodiment.

[0086] Main control device 30 predicts the amount of purchased power with discharge assistance (PV assistance) from solar panel 24 (S41).

[0087] If the amount of purchased power exceeds the alert threshold (S42: YES), the main control device 30 predicts the future amount of purchased power (S43) with discharge assistance by the battery 22. If the amount of purchased power does not exceed the alert threshold (S42: NO), the main control device 30 does not perform discharge assistance by the battery 22 (S420).

[0088] If the amount of purchased energy exceeds the alert threshold during the predetermined period (within 30 minutes of the end of the period) (S44: YES), the main control device 30 issues an alert (S45). If the amount of purchased energy does not exceed the alert threshold during the predetermined period (within 30 minutes of the end of the period) (S44: NO), the main control device 30 does not issue an alert.

[0089] In the above description, the alert issuance threshold line is set to have a small slope relative to the demand boundary line. However, the alert issuance threshold line may have an initial value (for example, a value at the timing of switching from the first time slot to the second time slot in the third aspect) set lower than the demand boundary line, and the slope may be the same.

[0090] <1> A plurality of loads connected to a power grid; a current sensor provided at a connection point between the power grid and the plurality of loads; A storage battery and a storage battery power conditioner connected to the power grid, converting AC power supplied from the power grid into DC power to charge the storage battery, and converting DC power discharged from the storage battery into AC power to supply the AC power to the plurality of loads; a control unit that controls charging and discharging of the storage battery based on the amount of power purchased from the power grid calculated from the value of the current sensor; Equipped with The control unit When it is determined that the purchased power amount within a predetermined period exceeds an alert issuance threshold, power is supplied from the storage battery to the plurality of loads by discharging through the storage battery power conditioner; Furthermore, when it is determined that the decrease in the amount of purchased power within the predetermined period due to the discharge still exceeds the alert issuance threshold, an alert is issued. 1. A power system comprising:

[0091] <2> A plurality of loads connected to a power grid; a current sensor provided at a connection point between the power grid and the plurality of loads; A storage battery and Solar panels and a storage battery power conditioner connected to the power grid, converting AC power supplied from the power grid into DC power to charge the storage battery, and converting DC power discharged from the storage battery into AC power to supply the AC power to the plurality of loads; a PV power conditioner connected to the power grid, converting DC power discharged from the solar panels into AC power and supplying the AC power to the plurality of loads; a control unit that controls charging and discharging of the storage battery based on the amount of power purchased from the power grid and the amount of power generated by the solar panel, the amount of power purchased from the power grid being calculated from the value of the current sensor; Equipped with The control unit When it is determined that the purchased power amount within a predetermined period, including the amount of power generated by the solar panel, exceeds an alert issuance threshold, power is supplied from the storage battery to the plurality of loads by discharging through the storage battery power conditioner; Furthermore, when it is determined that the amount of purchased electricity within the predetermined period that is reduced due to the discharge, including the amount of power generated by the solar panel, exceeds the alert issuance threshold, an alert is issued. 1. A power system comprising:

[0092] <3> a plurality of switches that can individually disconnect the plurality of loads from the power grid, The control unit is capable of individually controlling the disconnection of the plurality of loads. characterized in that <1> or <2> The power system described in

[0093] <4> The control unit During a first time period corresponding to the first half of the predetermined period, an alert determination is not made using the alert issuance threshold value, determining whether the amount of purchased electricity within the predetermined period that is reduced by the discharge still exceeds the alert threshold during a second time period after the first time period has elapsed; characterized in that <1> ~ <3> 10. The power system according to claim 9, wherein:

[0094] <5> The control unit detecting that surplus power that is not consumed by the plurality of loads is being charged among the AC power that is discharged from the PV power conditioner to the plurality of loads; And when it is predicted that a reverse power flow to the power system will occur, Instruct the PV power conditioner to suppress power generation of the solar panel; characterized in that <2> The power system described in [Explanation of symbols]

[0095] 10, 10A: Power system 20: Power facilities 21: Battery power conditioner 22: Battery 23: PV power conditioner 24: Solar panels 30: Main control unit 90: Communication terminal 200: Power transmission line 210: PCS control circuit 211: Inverter 212: Bidirectional DC-DC converter 230: PCS control circuit 231: Inverter 232: PV converter 291, 292, 293, 294: Load RL1, RL2: Grid connection relay S1, S2, S3, S4: Switches

Claims

1. A plurality of loads connected to a power grid; a current sensor provided at a connection point between the power grid and the plurality of loads; A storage battery and a storage battery power conditioner connected to the power grid, converting AC power supplied from the power grid into DC power to charge the storage battery, and converting DC power discharged from the storage battery into AC power to supply the AC power to the plurality of loads; a control unit that controls charging and discharging of the storage battery based on the amount of power purchased from the power grid calculated from the value of the current sensor; Equipped with The control unit When it is determined that the purchased power amount within a predetermined period exceeds an alert issuance threshold, power is supplied from the storage battery to the plurality of loads by discharging through the storage battery power conditioner; Furthermore, when it is determined that the decrease in the amount of purchased power within the predetermined period due to the discharge still exceeds the alert issuance threshold, an alert is issued.

1. A power system comprising:

2. A plurality of loads connected to a power grid; a current sensor provided at a connection point between the power grid and the plurality of loads; A storage battery and Solar panels and a storage battery power conditioner connected to the power grid, converting AC power supplied from the power grid into DC power to charge the storage battery, and converting DC power discharged from the storage battery into AC power to supply the AC power to the plurality of loads; a PV power conditioner connected to the power grid, which converts DC power discharged from the solar panel into AC power and supplies the AC power to the plurality of loads; a control unit that controls charging and discharging of the storage battery based on the amount of power purchased from the power grid and the amount of power generated by the solar panel, the amount of power purchased from the power grid being calculated from the value of the current sensor; Equipped with The control unit When it is determined that the purchased power amount within a predetermined period, including the amount of power generated by the solar panel, exceeds an alert issuance threshold, power is supplied from the storage battery to the plurality of loads by discharging through the storage battery power conditioner; Furthermore, when it is determined that the amount of purchased electricity within the predetermined period that is reduced due to the discharge, including the amount of power generated by the solar panel, exceeds the alert issuance threshold, an alert is issued.

1. A power system comprising:

3. a plurality of switches that can individually disconnect the plurality of loads from the power grid, The control unit is capable of individually controlling the disconnection of the plurality of loads. The power system according to claim 1 or 2, characterized in that:

4. The control unit During a first time period corresponding to the first half of the predetermined period, no alert determination is made using the alert issuance threshold value, determining whether the amount of purchased power within the predetermined period that is reduced due to the discharge still exceeds the alert issuance threshold during a second time period after the first time period has elapsed; The power system according to claim 1 or 2, characterized in that:

5. The control unit Detecting that surplus power that is not consumed by the plurality of loads is being charged among the AC power that is discharged from the PV power conditioner to the plurality of loads, And when it is predicted that a reverse power flow to the power system will occur, Instructing the PV power conditioner to suppress power generation of the solar panel; 3. The power system according to claim 2 .

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