Power control system

Abstract

To provide a power control system in which current conversion loss is reduced.SOLUTION: The power control system 1 includes an operation mechanism 100 that performs power generation, current conversion, and power supply to various loads, and a control mechanism 200 that is connected to various facilities of the operation mechanism 100, predicts a predicted power generation amount and a predicted power consumption amount, and controls the operation mechanism 100 based on the prediction result. When the predicted power generation amount from a certain time until the unit time elapses is less than the predicted power consumption amount of the DC load 5, the control mechanism 200 supplies the entire generated power of the power generation device 2 to the DC load 5, and supplies the shortage of the power consumption of the DC load 5 from the power storage device 3 when the remaining power storage amount is equal to or more than a predetermined amount, and supplies the shortage from the AC power supply 4 when the remaining power storage amount is less than the predetermined amount.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power control system for controlling power supply from a power generation device, a power storage device, and an AC power source to a DC load and an AC load. [Background technology]

[0002] Conventionally, there is known a power control system that determines whether to supply power from a power storage device or from a commercial power source based on the AC / DC conversion characteristics and the charge / discharge characteristics of the power storage device. For example, Patent Document 1 describes a power control method that determines whether to use a PSU or a storage battery, or both, as a supply source for supplying power to a power consumption unit, taking into account the conversion efficiency of the PSU as well as the charge / discharge characteristics of the storage battery, and also determines whether to charge the storage battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-50277 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the conventional power control system described above prioritizes power supply from the power storage device, and is configured to supply power from the power storage device regardless of whether it is a DC or AC load, and then supply power from an AC power source such as a commercial power source when the remaining charge in the power storage device becomes low. This poses the problem of large conversion losses from DC current to AC current and / or from AC current to DC current.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a power control system that reduces current conversion loss. [Means for solving the problem]

[0006] In order to achieve the above object, the invention described in claim 1 comprises a power generation device that supplies DC power, a power storage device that stores surplus power generated by the power generation device, an AC power source that supplies AC power, a load consisting of a DC load and an AC load, a storage unit that stores information on past power consumption amounts of the load and obtains weather forecast information, a prediction unit that predicts future power generation amounts of the power generation device and power consumption amounts of the load, and a power control unit that controls power conversion, wherein the power generation device, the power storage device, and the DC load are connected to a DC electric circuit through which a DC current flows, and the AC power source and the AC load are connected to an AC electric circuit through which an AC current flows, and a power control unit is provided between the DC electric circuit and the AC electric circuit. A conversion unit is provided that converts between DC and AC currents through control, and the prediction unit predicts a predicted power generation amount, which is the power generated by the power generation device until a unit time has elapsed from a certain time based on weather forecast information, and a predicted power consumption amount, which is the power consumption of the load until a unit time has elapsed from a certain time based on power consumption information, and if the predicted power generation amount is less than the predicted power consumption of the DC load and the remaining storage capacity of the storage device is equal to or greater than a predetermined amount, the power control unit supplies all of the generated power of the power generation device to the DC load until a unit time has elapsed from a certain time, and compensates for the shortfall in power consumption of the DC load with the stored power, thereby not converting the AC power from the AC power source to DC. Furthermore, the invention described in claim 2 is characterized in that, in the invention described in claim 1, if the predicted power generation amount from a certain time until a unit time has elapsed is less than the predicted power consumption of the DC load and the remaining stored power is less than a predetermined amount, the power control unit does not supply the stored power of the storage device by operating the DC load using the generated power of the power generation device and the AC power source until a unit time has elapsed from the certain time. Furthermore, the invention described in claim 3 is characterized in that, in the invention described in claim 1, when the predicted amount of power generation from a certain time until a unit time has elapsed is greater than the predicted power consumption of the load and the storage device is not fully charged, the power control unit supplies power from the power generation device to the load until a unit time has elapsed from the certain time, and stores the surplus power generated by the power generation device, excluding the power supplied to the load, in the storage device. Furthermore, the invention described in claim 4 is characterized in that, in the invention described in claim 1, when the predicted amount of power generation from a certain time until a unit time has elapsed is greater than the predicted power consumption of the DC load and the storage device is not fully charged, the power control unit supplies power from the power generation device to the DC load until a unit time has elapsed from the certain time, and stores the surplus of the power generated by the power generation device, excluding the power supplied to the DC load, in the storage device. Furthermore, the invention described in claim 5 is characterized in that, in the inventions described in claims 1 to 4, the prediction unit creates a control table in which the predicted power generation amount and predicted power consumption amount for a predetermined period from a predetermined time are recorded for each unit time, and the power control unit performs control based on the information recorded in the control table. [Effects of the Invention]

[0007] According to the present invention, the power control unit controls the power supply to the DC load and the AC load by referring to the predicted power generation amount and predicted power consumption amount predicted by the prediction unit.If the predicted power consumption amount of the DC load from a certain time until a unit time has elapsed is greater than the predicted power generation amount, the DC load is supplied with power from the power generation device, and if the remaining storage amount of the storage device is equal to or greater than a predetermined amount, the shortfall is supplied with power from the storage device.

[0008] Therefore, in the present invention, even if the generated power is predicted to be less than the power consumption of the DC load, if the remaining storage capacity is equal to or greater than a predetermined amount, power is supplied from the storage device, so there is no need to convert the AC power from the AC power source to DC, and it is possible to reduce power conversion losses. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing a power control system according to the present invention; [Figure 2] FIG. 2 is a block diagram showing a control mechanism. [Figure 3] 10 is a flowchart showing a control method of the power control unit. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present invention will now be described with reference to the accompanying drawings. Fig. 1 is a block diagram showing a power control system 1 according to the present invention. Fig. 2 is a block diagram showing a control mechanism 200. Fig. 3 is a flowchart showing a control method of the power control unit 14.

[0011] As shown in FIG. 1, the power control system 1 comprises an operating mechanism 100 that generates power, converts current, and supplies power to various loads, and a control mechanism 200 that is connected to various equipment of the operating mechanism 100 and controls the operating mechanism 100.

[0012] The operating mechanism 100 includes a power generation device 2 that generates solar power and supplies DC power, a power storage device 3 that stores surplus power generated by the power generation device 2, an AC power source 4 that supplies AC power from a public power company or the like, a DC load 5 that requires DC current for operation, an AC load 6 that requires AC current for operation, and a conversion device 7 that converts DC current to AC current and AC current to DC current.

[0013] In the operating mechanism 100, the power generation device 2, the power storage device 3, and the DC load 5 are connected to an electric circuit L1 through which a DC current flows. In addition, in the operating mechanism 100, the AC power supply 4 and the AC load 6 are connected to an electric circuit L2 through which an AC current flows. The converter 7 is installed between the electric circuits L1 and L2 and converts DC current into AC current and vice versa. The operating mechanism 100 also has instrument current transformers 9, 9 on the electric circuits L1, L2 connected to the DC load 5 and the AC load 6, for measuring the amount of power supplied to the DC load 5 and the AC load 6, respectively.

[0014] The power generation device 2 is a device that supplies DC current by solar power generation or the like. The power storage device 3 is a device that stores surplus power generated by the power generation device 2 and supplies power to a DC load 5 and an AC load 6 as needed. The DC load 5 is a device that requires DC current to operate, such as a server or personal computer used in a data center. The AC load 6 is a device that requires AC current to operate, such as a lighting fixture.

[0015] As shown in Figure 2, the control mechanism 200 includes an information acquisition unit 11 that acquires weather forecast information and the power consumption of each load, a prediction unit 12 that performs calculations based on the information acquired by the information acquisition unit 11 to predict the predicted power generation amount of the power generation device 2 and the predicted power consumption of each load, a memory unit 13 that stores the information acquired by the information acquisition unit 11 and the prediction results by the prediction unit 12, and a power control unit 14 that is connected to various facilities of the operating mechanism 100 and controls the power supply to the DC load 5 and the AC load 6 based on the prediction results of the prediction unit 12.

[0016] The information acquisition unit 11 includes a communication unit 11a for communicating with the outside to acquire weather forecast information, a measurement unit 11b connected to the power storage device 3 and the instrument current transformers 9, 9 for measuring the remaining amount of stored power in the power storage device 3 and the amount of power consumed by each load, and an acquisition unit CPU 11c for controlling the information acquisition unit 11. The information acquisition unit 11 acquires weather forecast information from, for example, the Japan Weather Association's cloud weather forecast information via the communication unit 11a and stores the information in the storage unit 13. In this embodiment, the weather forecast information stored in the storage unit 13 is the amount of predicted solar radiation. The information acquisition unit 11 also appropriately measures the remaining amount of stored power in the power storage device 3 via the measurement unit 11b, and records the amount of power supplied to each of the DC load 5 and the AC load 6 calculated based on the current information measured by the instrument current transformers 9, 9 together with the time and stores the information in the storage unit 13.

[0017] The weather forecast information stored in the storage unit 13 may be created based on information from the past few years (for example, five years) or may be created from weather forecasts that are updated from time to time. The past power consumption amounts stored in the storage unit 13 may be updated daily, may be an average of information from multiple days (for example, five days), may be an average of information from several weeks (for example, five weeks) by day of the week, or may be an average of information from several years (for example, five years) by date.

[0018] The prediction unit 12 has a prediction CPU 12a for making predictions. The prediction unit 12 predicts the predicted power generation amount and predicted power consumption amount for 24 hours from a predetermined time (for example, 6:00 a.m.) at a predetermined time every day. At this time, the prediction unit 12 predicts the predicted power generation amount and predicted power consumption amount for each unit time (for example, 5 minutes) from the predetermined time. The prediction unit 12 then stores the prediction results in the storage unit 13 as a control table, which is a time table in which the predicted power generation amount and predicted power consumption amount for each unit time from the predetermined time are recorded. Note that the prediction unit 12 refers to weather forecast information stored in the storage unit 13 when predicting the predicted power generation amount, and refers to past power consumption amounts stored in the storage unit 13 when predicting the predicted power consumption amount.

[0019] The power control unit 14 has a control CPU 14a that is connected to various equipment of the operating mechanism 100 and controls the operating mechanism 100. The power control unit 14 controls the power supply to the DC load 5 and the AC load 6 for each unit time from a predetermined time in accordance with the control table. Specifically, as will be described later, the power control unit 14 compares the predicted power generation amount and predicted power consumption amount for each unit time recorded in the control table, and determines and controls the control for the corresponding unit time based on the comparison result. In addition to controlling the power supply to each load, the power control unit 14 also performs control such as storing surplus power generated by the power generation device 2 in the power storage device 3 as necessary.

[0020] A specific control method by the power control unit 14 will be described below with reference to FIG. The power control unit 14 compares the predicted power generation amount and predicted power consumption amount for each section from a certain time until a unit time has elapsed in the control table, and determines and controls the operation for that section, according to the flowchart shown in Fig. 3. Here, the section from a certain time until a unit time has elapsed in the control table is defined as the control section. The predicted power consumption amount by the DC load 5 is defined as the predicted DC consumption amount, the predicted power consumption amount by the AC load 6 is defined as the predicted AC consumption amount, and the sum of the predicted DC consumption amount and the predicted AC consumption amount is defined as the predicted total consumption amount.

[0021] A specific description will be given of the flowchart in Fig. 3. First, the power control unit 14 determines whether the predicted power generation amount in the control section is equal to or greater than the predicted total consumption amount (S100).

[0022] In step S100, if the predicted power generation amount is equal to or greater than the predicted total consumption amount, the power control unit 14 controls the power generation device 2 to supply power to both the DC load 5 and the AC load 6 in the control section (S101). At this time, if the power storage device 3 is not fully charged, the power control unit 14 controls the power storage device 3 to store the surplus power generated by the power generation device 2, minus the power supply to each load.

[0023] If the predicted power generation amount is less than the predicted total consumption amount in step S100, the power control unit 14 then determines whether the predicted power generation amount in the control section is equal to or greater than the predicted DC consumption amount (S102).

[0024] In step S102, if the predicted power generation amount is equal to or greater than the predicted DC consumption amount, the power control unit 14 controls the power generation device 2 to supply power to the DC load 5 in the control section (S103). At this time, the power control unit 14 controls the AC load 6 so that the surplus power generated by the power generation device 2 minus the power supply to the DC load 5 is supplied to the AC load 6, and the shortage is made up for by the AC power source 4.

[0025] If the predicted power generation amount is less than the predicted DC consumption amount in step S102, the power control unit 14 then determines whether the remaining amount of stored power in the power storage device 3 in the control section is equal to or greater than a predetermined amount (S104). Note that the predetermined amount is a remaining amount that is left in advance so that the power storage device 3 can be used as a power source in an emergency, and is determined appropriately, and may be, for example, 30% of a full charge.

[0026] In step S104, if the remaining amount of stored power in the power storage device 3 is equal to or greater than a predetermined amount, the power control unit 14 controls the power storage device 3 to supply power to the DC load 5 in the control section so that a predetermined amount remains in the power storage device 3 together with the power generation device 2 (S105). At this time, if the power supply to the DC load 5 is insufficient, the power control unit 14 controls the power supply to be supplemented by the AC power source 4. The power control unit 14 also controls the AC power source 4 to supply power to the AC load 6.

[0027] In step S104, if the remaining amount of stored electricity in the electricity storage device 3 is less than a predetermined amount, the power control unit 14 controls the power supply so that power is supplied from the AC power source 4 to the DC load 5 in addition to the power generation device 2 in the control section (S106). At this time, the power control unit 14 controls the AC power source 4 to supply power to the AC load 6.

[0028] In steps S101 and S102, if the storage device 3 is not fully charged and the power loss caused by the conversion from DC current to AC current by the conversion device 7 is greater than the power loss caused by charging the storage device 3 from the power generation device 2, the surplus power generated by the power generation device 2, minus the power supplied to the DC load 5, may be stored in the storage device 3 without being supplied to the AC load 6.

[0029] In this way, the power control unit 14 performs the operations from step S101 to 106 for each control section, thereby performing control for each unit time based on the control table.

[0030] According to the above-described power control system 1, the power control unit 14 controls the power supply to the DC load 5 and the AC load 6 by referring to the predicted power generation amount and predicted power consumption amount predicted by the prediction unit 12. If the predicted DC consumption amount from a certain time until the elapse of a unit time is greater than the predicted power generation amount, the DC load 5 is supplied with power generated by the power generation device 2, and if the remaining amount of power stored in the storage device 3 is equal to or greater than a predetermined amount, the shortfall is supplied with power from the storage device 3.

[0031] Therefore, even if the power generated by the power generation device 2 is predicted to be less than the power consumption of the DC load 5, if the remaining amount of stored power is equal to or greater than a predetermined amount, the power control system 1 supplies power from the power storage device 3, so there is no need to convert the AC power from the AC power source 4 to DC, and it is possible to reduce the loss of power conversion.

[0032] The power control system according to the present invention is not limited to the above-described embodiment, and the overall configuration of the power control system as well as the operation of the operating mechanism and control mechanism can be appropriately modified as needed.

[0033] For example, in the embodiment, the control table is configured to update a one-day timetable every day, but it may also be created by predicting several days' worth of data at once. In the embodiment, the power generation device 2 generates power using sunlight, but it may also be configured to generate power using other natural energy sources such as wind power or hydraulic power. Accordingly, the information acquisition unit 11 acquires weather forecast information according to the changed power generation method, instead of the predicted amount of solar radiation. Furthermore, the CPUs provided in the components of the control mechanism 200 may be separate or integrated. [Explanation of symbols]

[0034] 1·· Power control system, 2·· Power generation device, 3·· Power storage device, 4·· AC power source, 5·· DC load, 6·· AC load, 7·· Conversion device, 9·· Instrument current transformer, 11·· Information acquisition unit, 12·· Prediction unit, 13·· Memory unit, 14·· Power control unit, 100·· Operating mechanism, 200·· Control mechanism

Claims

1. a power generation device that supplies DC power, a power storage device that stores surplus power generated by the power generation device, an AC power supply that supplies AC power, a load consisting of a DC load and an AC load, a storage unit that stores past power consumption amount information of the load and obtains weather forecast information, a prediction unit that predicts future power generation amount of the power generation device and future power consumption amount of the load, and a power control unit that controls power conversion, the power generation device, the power storage device, and the DC load are connected to a DC circuit through which a DC current flows, and the AC power supply and the AC load are connected to an AC circuit through which an AC current flows, a converter that converts DC current into AC current and vice versa under the control of the power control unit is provided between the DC current circuit and the AC current circuit; the prediction unit predicts a predicted power generation amount, which is the power generated by the power generation device from a certain time until a unit time has elapsed, based on the weather forecast information, and a predicted power consumption amount, which is the power consumption amount of the load from a certain time until a unit time has elapsed, based on the power consumption amount information; the power control unit supplies all of the generated power of the power generation device to the DC load until a unit time has elapsed from a certain time, if the predicted amount of power generation is less than the predicted amount of power consumption of the DC load and the remaining amount of power stored in the power storage device is equal to or greater than a predetermined amount, and compensates for any shortfall in power consumption of the DC load with stored power, thereby not converting AC power from the AC power source to DC.

2. 2. The power control system according to claim 1, wherein, if the predicted amount of power generation from a certain time until a unit time has elapsed is less than the predicted power consumption of the DC load and the remaining amount of stored power is less than a predetermined amount, the power control unit does not supply the stored power of the power storage device by operating the DC load using the generated power of the power generation device and the AC power supply until a unit time has elapsed from the certain time.

3. 2. The power control system according to claim 1, wherein, when the predicted amount of power generation until a unit time has elapsed from a certain time is greater than the predicted power consumption of the load and the storage device is not fully charged, the power control unit causes the power generation device to supply power to the load until a unit time has elapsed from the certain time, and causes the storage device to store an excess of the power generated by the power generation device, excluding the power supplied to the load.

4. 2. The power control system according to claim 1, wherein, when the predicted amount of power generation until a unit time has elapsed from a certain time is greater than the predicted power consumption of the DC load and the power storage device is not fully charged, the power control unit causes the power generation device to supply power to the DC load until a unit time has elapsed from the certain time, and causes the power storage device to store an excess of the power generated by the power generation device, excluding the power supplied to the DC load.

5. the prediction unit creates a control table in which predicted amounts of power generation and power consumption for a predetermined period from a predetermined time are recorded for each unit time, 5. The power control system according to claim 1, wherein the power control unit performs control based on information recorded in the control table.

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