Power Control Device

Abstract

To provide a charging and discharging method for maintaining a demand value.SOLUTION: A power control device that perform charging and discharging control on a storage battery installed in a consumer facility of an electric power system, comprises: a communication unit that receives electric power measured at a power reception point from an electric power system; and a processor that controls a power conversion device to perform charging and discharging control on the storage battery in a first period, and acquires and holds electric power in a second period shorter than the first period while holding a maximum demand value. The processor calculates a first predicted power W1 at a time t3 of end of the current first period, calculates a statistical variation of the power acquired in the second period measured in the current first period, and calculates a corrected predicted power W3 at the time t3 by adding the first prediction power to the statistical variation. If the corrected predicted power exceeds the maximum demand value, a control command to discharge power is output to the storage battery.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a power control device that controls charging and discharging of a storage battery. [Background technology]

[0002] The basic electricity charge in the contract between an electric power company and an electric power consumer is determined based on the maximum demand value over the past year. The maximum demand value is the average power consumption over a 30-minute period. Therefore, electric power consumers calculate the predicted demand value for the demand period based on the power consumption trend, and if the predicted demand value is expected to exceed the base value for the basic charge, they adjust the load to take measures to reduce power consumption.

[0003] Furthermore, in recent years, renewable energy sources have been connected to the grid, and the demand side is also required to change its demand in response to sudden changes in grid output (called demand response). For example, if the solar power generation forecast is wrong and the sky is cloudy, supply will be insufficient, so the demand side is required to reduce demand (called downward demand response). In such cases, the demand value, which was previously set with the purpose of reducing the basic charge, needs to be reduced for a certain period of time to the reduced demand value. In such cases, the demand value is not only used to calculate the basic charge, but is also used as a value for the reduced demand, and measures to reduce power consumption are taken.

[0004] For example, Patent Document 1 discloses a battery control system that controls the discharge of power stored in a battery system of a consumer that is a target for demand cutting so that the integrated received amount of grid power from the start of each demand cutting period (hereinafter referred to as a DC period) of the consumer that is the target of demand cutting does not exceed a predetermined target value within each DC period. The battery control system includes a data storage unit that records a first reference received amount of power that serves as a reference for determining whether or not to discharge the battery system, with respect to the integrated received amount of power during each elapsed time from the start of each DC period for each first unit time that is an even division of the length of the DC period; a data communication unit that transmits and receives data to and from the battery system; and a data communication unit that transmits and receives data to and from the battery system, and determines, for each first unit time, whether the integrated received amount of power is greater than the first reference received amount, based on received power amount data that indicates the integrated received amount from the start of the DC period to the elapsed time, and determines, based on the received power amount data that is received at a predetermined reception timing via the data communication unit, whether or not the integrated received power amount is greater than the first reference received amount. and a battery control unit that transmits discharge command data to the battery system via the data communication unit when it determines that the received power amount is equal to or greater than the quasi-received power amount, wherein during each DC period, the first reference received power amount is set to monotonically increase from a lower limit value to an upper limit value as the elapsed time increases for each first unit time, and when the accumulated received power amount that increases linearly from 0% to 100% of the target value as the elapsed time increases from the start to the end of the DC period is defined as the target accumulated received power amount, the difference obtained by subtracting the first reference received power amount from the target accumulated received power amount monotonically increases during a first initial period from the start of each DC period until a predetermined time has elapsed, reaches a maximum positive value at the end of the first initial period, and monotonically decreases from the end of the first initial period until the first reference received power amount reaches the upper limit value. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-167756 Summary of the Invention [Problem to be solved by the invention]

[0006] In this way, conventionally, battery discharge control is performed during the demand cut period to maintain the demand value. However, there is no disclosure of the issue of minimizing the capacity of the battery by charging during the demand cut period.

[0007] The present invention has been made in view of the above circumstances, and has as its object to minimize the rechargeable battery capacity required for controlling the power demand to be equal to or less than the power demand by efficiently charging the storage battery. [Means for solving the problem]

[0008] In order to solve the above problems, the embodiments of the present invention have the following configurations 1 to n. [Item 1] A power control device that controls charging and discharging of a storage battery installed in a consumer facility of a power system via a power conversion device, a communication unit that receives power measured at a power receiving point where power is input from a power grid; a processor that controls the power conversion device to control charging and discharging of the storage battery in a first period, acquires and stores power in a second period that is shorter than the first period, and stores a maximum demand value; Equipped with The processor: A first predicted power (W1) at time t3, which is the end of the current first period (P1a), is calculated using the following formula:

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[0009] According to the present invention, by efficiently discharging the storage battery, it is possible to minimize the rechargeable battery capacity required for controlling the power demand to be below the demand. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating the overall configuration of a power control device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a diagram illustrating details of a power control device according to an embodiment of the present invention. [Figure 3] 3 is a diagram illustrating discharge control to a rechargeable battery by a power control device according to an embodiment of the present invention. FIG. [Figure 4] 3 is a diagram illustrating charging control of a rechargeable battery by a power control device according to an embodiment of the present invention. FIG. [Figure 5] 3 is a power control flowchart of a power control device according to an embodiment of the present invention. [Figure 6A] 10 is a graph showing power consumption in conventional control. [Figure 6B] 10 is a graph showing changes in power consumption in conventional control. [Figure 7A] 1 is a power consumption graph with general demand control. [Figure 7B] 1 is a graph showing changes in power consumption with general demand control. [Figure 8A] 10 is a graph showing power consumption when demand control according to the present invention is performed. [Figure 8B] 1 is a graph showing changes in power consumption according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The power control device according to this embodiment will be described below with reference to FIGS.

[0012] 1. Configuration of power control device 1 is a diagram illustrating the overall configuration of a power control device and related devices according to one embodiment of the present invention. Power equipment 11 of a consumer 7 includes a power receiving point 12 connected to an external power system (system) 10, a transformer facility 13, a load 14, a storage battery 15, a power conversion device 16 for the storage battery, and a power control device 20. The power control device 20 is connected by communication so as to receive received power data from a power detection sensor 161 connected to the power receiving point 12. The power control device 20 is also connected by communication with the power conversion device 16 and the storage battery 15.

[0013] The power conversion device 16 is provided for each storage battery 15, and performs AC-DC conversion of the power to charge the storage battery 15 or DC-AC conversion of the power output by discharging the storage battery 15. The power conversion device 16 has a circuit including a switching element, and is connected to the storage battery 15 via DC, but performs DC-AC conversion by boosting the DC to a predetermined voltage and converting it to AC, and also performs AC-DC conversion as the reverse operation.

[0014] The storage battery 15 is a stationary storage battery provided in a consumer facility or a battery in an electric vehicle, and stores the power input during charge control and discharges the stored power for output. The storage battery 15 includes, for example, a secondary battery such as a lithium-ion battery, a lead-acid battery, or a nickel-metal hydride battery. The storage battery 15 includes a battery management unit that monitors the remaining battery charge, and transmits information about the battery state (voltage, SOC, etc.) to the power control device 20.

[0015] 2 is a diagram illustrating the configuration of a power control device. The power control device 20 may be configured as a computer device including a processor 22, a memory 24, a communication unit 26, a storage 28, and a bus 29. Each device is connected by the bus 29 for communicating information.

[0016] The processor 22 controls the entire computer by running, for example, an operating system. The processor 22 may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control device, an arithmetic unit, a register, etc. The processor 22 also reads programs (program codes), software modules, and data from the storage 28 and / or the communication unit 26 into the memory 24 and executes various processes in accordance with the programs. The programs used are those that cause the computer to execute at least some of the operations described in the above-described embodiments. For example, each functional unit of the power control device 20 may be implemented by a control program stored in the memory 24 and executed by the processor 22, and similar programs may be implemented for other functional blocks. The programs may also be transmitted from a network via a telecommunications line.

[0017] The memory 24 is a computer-readable recording medium and may be composed of at least one of, for example, a read-only memory (ROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a random access memory (RAM), etc. The memory 24 may also be called a register, a cache, a main memory (primary storage device), etc. The memory 24 can store an executable program (program code), software modules, etc. for implementing a method according to one embodiment of the present invention.

[0018] Storage 28 is a computer-readable recording medium and may be composed of at least one of, for example, an optical disk such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, a Blu-ray® disk), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy disk, a magnetic strip, etc. Storage 28 may also be referred to as an auxiliary storage device.

[0019] The communication unit 26 is hardware (transmission / reception device) for communicating between computers via a wired and / or wireless network, and is also called, for example, a network device, a network controller, a network card, or a communication module.

[0020] The power control device 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), and a field programmable gate array (FPGA).

[0021] 2. Control method of the control unit 2.1 Battery discharge control Using Figure 3, we will explain how the power control device controls the discharge of the rechargeable battery. In Figure 3, the vertical axis represents the power at the receiving point, and the horizontal axis represents time. 200a represents the power demand, which increases and decreases over time like a sine curve. DV is the received power, which indicates the demand value.

[0022] The power control device 20 controls the charging and discharging of the storage battery every first period P1. Here, the first period is a 30-minute time interval, which is the unit of time for trading electricity. Furthermore, the power control device 20 acquires electricity every time of a second period P2, which is shorter than the first period, and stores the electricity in memory. The second period P2 is, for example, every minute. The maximum demand value is also stored in memory. In FIG. 6, the first period (P1a) that is the target of calculation processing by the processor will be used for explanation.

[0023] The processor 22 of the power control device 20 calculates the first predicted power (W1) at time t3, which is the end of the current first period (P1a), using the following formula.

[0024]

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[0025] The processor 22 calculates the statistical variation of the power acquired in the second period measured in the current first period (P1a), and calculates the corrected predicted power W3 at time t3 by adding the first predicted power and the statistical variation. If the corrected predicted power W3 exceeds the maximum demand value, the processor 22 outputs a control instruction to the storage battery to discharge.

[0026] The statistical variation is, for example, the standard deviation σ, which is derived from the following number:

[0027]

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[0028] The discharge power to the storage battery is a value obtained by subtracting the maximum demand value DM from the corrected predicted power W3.

[0029] 2.2 Storage battery charging Control Method Charging control of the rechargeable battery by the power control device will be described with reference to Fig. 4. Note that in Fig. 4, the description of the same configuration as in Fig. 3 will be omitted.

[0030] If the corrected predicted power W3 does not exceed the maximum demand value, the processor 22 calculates the second predicted power (W2) at time t3 at the end of the current first period (P1a) using the following formula:

[0031]

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[0032] When the value obtained by adding the second predicted power (W2) and the statistical variation is smaller than the maximum demand value, the processor outputs to the storage battery the power obtained by subtracting the statistical variation and the second predicted power from the maximum demand value. discharge The control instruction is output so that

[0033] 3. Power control flowchart A power control flowchart of the power control device will be described with reference to FIG. In S101, the power control device 20 acquires the power for the second period of the current period (P1a) from the power detection sensor. Next, the processor 22 determines whether W3 is greater than or equal to the maximum demand value (S102). If W3 is greater than the maximum demand value (Y in S102), the storage battery is controlled to perform a discharge process (S103), and the process returns to the initial process (S101) via S201. If W3 is less than the maximum demand value (N in S102), the process proceeds to S111.

[0034] In S111, the processor 22 determines whether "W3+σ" is smaller than the maximum demand DR. If "W3+σ" is smaller than the maximum demand DR (Y in S112), the processor 22 controls the storage battery to perform charging processing (S112). If "W3+σ" is larger than the maximum demand DR (N in S112), the process returns to S101. The process returns to the initial processing (S101) by S201. [Example]

[0035] An embodiment will be described below using FIGS. 6 to 8. FIG. 6A is a graph of power consumption without the control according to the present invention, and FIG. 6B is a graph of power consumption change without the control according to the present invention. FIG. 7A is a graph of power consumption with general demand control, and FIG. 7B is a graph of power consumption change with general demand control. FIGS. 6A and 7A show power usage, contracted power, target power, and power consumption. The power usage in FIG. 6A is used by loads 1 to 3 in FIGS. 6B and 7B, respectively. Current demand control is predictive control, and in the unlikely event that power usage exceeds the predicted level, it can only shed predetermined loads and cannot respond to unexpected power increases. Furthermore, because it is predictive control, power shed must be performed at a point with a sufficient margin relative to the contracted power. Depending on the prediction, it may not be possible to use enough power up to the contracted power, which reduces convenience.

[0036] Fig. 8A is a power consumption graph in which demand control according to the present invention is implemented, and Fig. 8B is a power consumption change graph in accordance with the present invention. Fig. 8A shows power usage, contracted power, target power, and power consumption. The power usage in Fig. 8A is used by loads 1 to 3 in Fig. 8B, respectively. As shown in Fig. 8A, battery discharge control is performed without exceeding the demand value.

[0037] The embodiments described above are merely typical examples, and combinations, modifications, and variations of the components of each embodiment will be apparent to those skilled in the art. It is clear that those skilled in the art can make various modifications to the above-described embodiments without departing from the principles of the present invention and the scope of the invention as set forth in the claims. [Explanation of symbols]

[0038] 10 External power system 11 Power equipment 12 Power receiving point 15 Storage battery 16 Power conversion device 20 Power control device

Claims

1. A power control device that controls charging and discharging of a storage battery installed in a consumer facility of a power system via a power conversion device, a communication unit that receives power measured at a power receiving point where power is input from a power grid; a processor that controls the power conversion device to perform charge / discharge control for the storage battery in a first period, acquires and holds power for each second period that is shorter than the first period, and holds a maximum demand value; Equipped with The processor: A first predicted power (W1) at time t3, which is the end of the current first period, is calculated using the following formula: [Equation 1] where t2 denotes the current time, P2 denotes the power measured at t2, t1 denotes a time after the beginning of the current first period and ahead of t2, and P1 denotes the power measured at t1; Calculating a statistical variation of the power acquired in the second period measured in the current first period; calculating a corrected predicted power at time t3 by adding the first predicted power and the statistical variation; When the corrected predicted power exceeds the maximum demand value, the power control device outputs a control instruction to the storage battery to discharge power obtained by subtracting the maximum demand value from the corrected predicted power.

2. If the corrected predicted power does not exceed the maximum demand value, a second predicted power (W2) at time t3, which is the end of the current first period, is calculated using the following formula: [Equation 2] where t4 denotes the start time of the current first period, P4 denotes the power measured at t4, The power control device according to claim 1 , further comprising: a control instruction to charge the storage battery with power obtained by subtracting the statistical variation and the second predicted power from the maximum demand value.

3. The power control device of claim 1 , wherein the statistical variation is a standard deviation.

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