WO2015056634A1

WO2015056634A1 - Electricity storage system

Info

Publication number: WO2015056634A1
Application number: PCT/JP2014/077113
Authority: WO
Inventors: 田中　融; 二見　基生; 松井　拓也
Original assignee: 新神戸電機株式会社
Priority date: 2013-10-17
Filing date: 2014-10-09
Publication date: 2015-04-23
Also published as: JPWO2015056634A1

Abstract

　Provided is a technique relating to an electricity storage system that makes it possible to minimize any decrease in the life of a storage battery by reducing loss through suitable control of an operation such as peak cutting. The electricity storage system performs: a process in which the value of a settable item for controlling a peak cutting operation is set by a user; a process for measuring status values including power received from a power system, load power from a load facility, and the voltage, current, and temperature of the storage battery; a process for calculating the SOC value using the measurement value; and a process for controlling charging and discharging of a plurality of storage batteries, including controlling peak cut operation, using the SOC value and the setting values. During peak cut operation, the electricity storage system discharges the storage battery when the load power is at a first load power or more, and charges the storage power when the load power is at a second load power or less, so that the load power is kept within the range from the first load power to the second load power.

Description

Power storage system

The present invention relates to a technology of a power storage system including a storage battery. The present invention also relates to control of power peak cut and peak shift.

Facilities such as offices, factories, and buildings operate in the daytime when people work and stop at night, so there is a difference in power consumption during the daytime. Eliminating this disparity in power consumption, that is, reducing or leveling the power load, is an important issue as an element for improving industrial competitiveness.

As a means for reducing or leveling the electric power load, there are a peak cut operation and a peak shift operation by controlling charging / discharging to a plurality of storage batteries by the power storage system. The peak cut operation suppresses the peak load power of the load facility by covering with the charge / discharge power of the storage battery. In the peak shift operation, the storage battery is charged in a predetermined time zone where the power demand is low, and the load power is leveled by discharging the storage battery in a predetermined time zone where the power demand is high.

JP, 2006-109621, A (patent documents 1) is mentioned as a prior art example about an electrical storage system. Patent Document 1 sets a load follow-up threshold for each time period in advance as an operation method of the power storage system, and controls charge / discharge based on a difference between the received power and the load follow-up threshold as a power load situation. , Is described.

JP 2006-109621 A

The peak cut and peak shift operations in the above power storage system are automatic operations that are assumed to be performed continuously for a long time. Moreover, the magnitude of the load power of the load facility to which the power storage system supplies power is not necessarily constant. Therefore, the automatic operation of the power storage system tends to cause the storage battery to be overdischarged or overcharged, resulting in a short life of the storage battery.

An object of the present invention is to provide a technique capable of suppressing the shortening of the life of a storage battery by reducing the loss by suitable control of operation such as peak cut in the power storage system.

A representative embodiment of the present invention is a power storage system having the following configuration.

An electric storage system according to an embodiment includes a control device connected to an electric power system and a load facility, and a plurality of storage batteries connected to the control device, and the control device is controlled based on a user operation. A setting unit that sets a value of a setting item for, a measuring unit that measures a value including a received power from the power system, a load power of the load facility, a voltage, a current, and a temperature of the storage battery; and A charge / discharge control unit that controls charging and discharging of the plurality of storage batteries, including control of peak cut operation that suppresses the peak of load power of the load facility by charging and discharging of the plurality of storage batteries, and the setting The unit sets a value of a setting item including a start time, an end time, a first load power, and a second load power of the peak cut operation, and the charge / discharge control unit sets the set peak cut operation At the start of When the load power is equal to or higher than the first load power, the storage battery is discharged so that the load power falls within the range between the first load power and the second load power in the time from the end time to the end time. Then, power is supplied to the load facility, and the storage battery is charged when the load power is equal to or lower than the second load power.

According to a typical embodiment of the present invention, it is possible to suppress the shortening of the life of the storage battery by reducing the loss by suitable control of operation such as peak cut in the power storage system.

It is a figure which shows the structure of the electrical storage system of Embodiment 1 of this invention. 3 is a diagram illustrating a functional block configuration of the power storage system according to Embodiment 1. FIG. 3 is a diagram illustrating a flow of control processing of the power storage system according to Embodiment 1. FIG. It is a figure which shows the peak cut driving | operation of the electrical storage system of a premise conventional example. 3 is a diagram illustrating a setting example regarding the SOC of the storage battery of the power storage system according to Embodiment 1. FIG. 6 is a diagram illustrating an operation example of peak cut operation of the power storage system according to Embodiment 1. FIG. 3 is a diagram showing a storage battery model and an SOC-OCV characteristic table of the power storage system of Embodiment 1. FIG. 3 is a diagram illustrating a screen example for setting the power storage system according to Embodiment 1. FIG. It is a figure which shows the comparison with the outline | summary of control of the electrical storage system of Embodiment 1, and the outline | summary of control of the electrical storage system of a prior art example. It is a figure which shows the peak shift driving | operation of the electrical storage system of a premise conventional example. It is a figure which shows the example of a screen of the setting of the electrical storage system of Embodiment 2 of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

<Embodiment 1>
A power storage system according to Embodiment 1 of the present invention will be described with reference to FIGS. The power storage system of Embodiment 1 has a control function of peak cut operation.

The power storage system of Embodiment 1 has a function of reducing loss by suitable control of operation such as peak cut in consideration of the life of the storage battery group. This function controls the charging and discharging of the storage battery group so as to correspond to the SOC range with less loss in consideration of the SOC of the storage battery (State Of Charge: referred to as a charging state or charging rate) during operation. This function controls charging and discharging of the storage battery group so that the load power falls within the range of the peak cut load and the reverse power load during a predetermined time as control of the peak cut operation.

This function measures the closed circuit voltage (CCV), current, temperature, etc. of the storage battery, calculates the open circuit voltage (OCV) using the measured value and the previous SOC value, and opens the circuit voltage (OCV). The latest SOC value is calculated using the SOC-OCV characteristic information of the storage battery and the like. This function controls charging and discharging of the battery group using the latest SOC value with high accuracy.

This function charges the storage battery in advance before the start time so that the SOC value becomes a predetermined SOC value at the start time of peak cut operation as control of protection of the storage battery.

This function is set to protect and start the discharge of the storage battery group when the latest SOC value is equal to or higher than the set first SOC value during peak cut operation as control of protection of the storage battery. When it is below the second SOC value, charging of the storage battery group is started and protected.

This function provides the user with a screen that serves as an interface that allows the setting items such as the SOC value range for each control to be set.

[Power storage system]
FIG. 1 shows a configuration of a system including a power storage system 1 according to the first embodiment. The power storage system 1 is connected to the power system 2, the load facility 3, the solar power generation system 4, and the like.

The power storage system 1 includes a control panel housing part 71 and a storage battery board housing part 72. The control panel accommodating part 71 accommodates the control panel and connects the storage battery panel accommodating part 72. The storage battery board accommodating part 72 accommodates a storage battery board. The storage battery panel connects a plurality of storage batteries in parallel and in series. The storage battery is, for example, a lithium ion secondary battery.

The control panel has power control functions including peak cut operation control and storage battery management. The power control function of the control panel controls the plurality of storage battery panels connected to the lower level, controls charging and discharging of the storage battery group, and manages the power constituted by the storage battery group. The power control function of the control panel includes a function of converting direct current (DC) and alternating current (AC) power.

50 indicates power measurement by the power storage system 1. The power measurement 50 includes measurement of received power 52 of the power system 2, measurement of load power 53 that is a load output of the load facility 3, measurement of generated power 54 of the solar power generation system 4, and the like. The power measurement 50 may use the information when information is obtained from the target.

62 indicates charging of the storage battery of the power storage system 1 by the received power 52 from the power system 2. Reference numeral 63 denotes an operation such as a peak cut including power feeding to the load facility 3 due to discharge of the storage battery of the power storage system 1. Reference numeral 64 denotes charging of the storage battery of the power storage system 1 by the generated power 54 from the solar power generation system 4. Reference numeral 65 denotes power feeding from the power system 3 to the load facility 3. 66 indicates the reverse power flow from the power storage system 1 or the photovoltaic power generation system 4 to the power system 2.

1 The system in FIG. 1 is in the form of grid connection. That is, the power storage system 1 and the solar power generation system 4 are connected to the power system 2, and a reverse power flow in which the power from the power storage system 1 and the solar power generation system 4 is supplied to the power system 2 occurs depending on the situation.

In the peak cut operation, the power storage system 1 charges the storage battery group with the received power 52 and the generated power 54, and discharges the storage battery group to supply power to the load facility 3 when the load facility 3 has a large load power. In a situation where the load power of the load facility 3 is small, the power storage system 1 generates a reverse power flow in which power from the discharge of the storage battery is supplied to the power system 2. In order to protect the power storage system 1 from overcharging and overdischarging due to the continuation of charging and discharging, control and the like using a threshold range of load power described later is performed.

The outline of control related to the peak cut operation of the electricity storage system 1 is as follows. In the power storage system 1, load power, an SOC threshold value, and the like are set according to a user's operation as a set value for controlling peak cut operation. The power storage system 1 measures the received power 52 from the power system 2 and the load power 53 of the load facility 3, and measures the state of the storage battery group such as the voltage. The power storage system 1 calculates the SOC values of the storage battery and the storage battery group using the measured value and the storage battery characteristic information. The power storage system 1 suitably controls charging / discharging of the storage battery group based on the set value, load power, and SOC value during peak cut operation.

In the power storage system 1, electric power is configured in units of a group of predetermined plural storage batteries, and charging / discharging is controlled in the units. The SOC of each storage battery in the unit is controlled to be a value within a predetermined accuracy range.

[Function block configuration]
FIG. 2 shows a functional block configuration of the power storage system 1. The power storage system 1 includes a control unit 101, a storage unit 102, and an input / output unit 103. The control unit 101 includes a setting unit 10, a first measurement unit 11, a second measurement unit 12, an SOC calculation unit 13, and a charge / discharge control unit 14. The charge / discharge control unit 14 includes a peak cut control unit 15, a first protection control unit 16, and a second protection control unit 17. The storage unit 102 stores setting information 20, measurement information 21, storage battery characteristic information 22, SOC information 23, and the like. The storage battery characteristic information 22 includes information such as the SOC-OCV characteristic table 25. The input / output unit 103 processes electrical connection and communication with each system such as the power system 2 in FIG. 1 and input / output of information to / from the user.

The setting unit 10 provides a setting screen as shown in FIG. 8, which will be described later, as a setting interface for the user, and performs setting processing for control setting values (step S1 in FIG. 3, which will be described later). The setting unit 10 displays information on each setting item for control on the screen, enables setting by the user, and stores the set setting value in the setting information 20.

The first measurement unit 11 measures the received power 52 from the power system 2, the load output 53 of the load facility 3, the generated power 54 of the solar power generation system 4 and the like corresponding to the power measurement 50 described above, and the measured value Is stored in the measurement information 21 (S2 described later). The control panel has a measurement function corresponding to the first measurement unit 11.

The 2nd measurement part 12 performs the process (S3 mentioned later) which measures the value of states, such as closed circuit voltage (CCV) of a storage battery group, an electric current, and temperature, and stores a measured value in the measurement information 21. FIG. This measurement means is realized by a measurement and monitoring function provided in at least one of the control panel and the storage battery panel. For example, each storage battery panel includes a storage battery monitoring unit, and the storage battery monitoring unit monitors and measures the value of the state including the closed circuit voltage, current, temperature, etc. of the storage battery, and the signal of the state and value based on this is transmitted to the control panel. Send. The control panel recognizes and determines the state of the storage battery group based on a signal from the storage battery panel.

The SOC calculation unit 13 uses the measurement information 21, the storage battery characteristic information 22, and the SOC information 23 to calculate the latest SOC value and store it in the SOC information 23 according to a CCV verification method described later (S4 described later). )I do.

The charging / discharging control part 14 performs the process (S5 mentioned later) which controls charging / discharging of a storage battery group including control of peak cut operation. The peak cut control unit 15 performs a later-described load fluctuation range control process (described later in S5-1) in the peak cut operation using a predetermined set value (described later, A1 to A4). The first protection control unit 16 performs a first storage battery protection control process (S5-2, which will be described later) using a predetermined set value (B1, which will be described later). The second protection control unit 17 performs a second storage battery protection control process (described later, S5-3) using a predetermined set value (described later, B2 to B5).

[Setting items]
A plurality of types of setting items in power storage system 1 of the first embodiment are as follows.

A1: Peak cut load [W]
A2: Reverse power load [W]
A3: Peak cut start time A4: Peak cut end time B1: Start SOC value [%]
B2: Discharge start SOC value [%]
B3: Discharge stop SOC value [%]
B4: Charging start SOC value [%]
B5: Charging stop SOC value [%].

In addition, A1 etc. show the code | symbol which identifies each setting item so that it may be easy to understand on description. The setting value of each setting item is displayed on the setting screen of FIG. 8 described later, and can be set by the user.

(1) The peak cut load A1 and the reverse power load A2 are threshold values of the load power range related to the control of the peak cut operation. The peak cut load A1 is the first load power that is the upper limit, and the reverse flow load A2 is the second load power that is the lower limit. The peak cut load A1 indicates a target level for suppressing the peak load power in the peak cut operation. The unit of load power is W (watt) or the like. The reverse power load A2 indicates a target level for suppressing the power of the reverse power flow in the peak cut operation. The reverse tide load A2 is a value of 0 or less.

The peak cut start time A3 and peak cut end time A4 define the time for peak cut, reverse power flow reduction and charge / discharge in peak cut operation. The peak cut start time A3 is the start time of the peak cut operation in one day, and the peak cut end time A4 is the end time of the operation from the peak cut start time A3. The load power 53 is monitored within the peak cut operation time of A3 to A4.

The power storage system 1 supplies power to the load facility 3 by discharging the storage battery when the load power 53 is greater than or equal to the peak cut load A1 within the time period A3 to A4. As a result, the peak of the load power 53 is suppressed so that it falls within the peak cut load A1. The power storage system 1 supplies power to the load facility 3 by charging the storage battery when the load power 53 is equal to or lower than the reverse power load A2 within the time period A3 to A4. Thereby, the power of the reverse power flow is reduced.

(2) The start SOC value B1 is the SOC target value at the peak cut start time A3. The power storage system 1 charges the storage battery from the peak cut end time A4 to the next peak cut start time A3 until the SOC value reaches the start SOC value B1. Depending on the situation, the SOC value may not be the same value as the start SOC value B1, but a corresponding effect can be obtained by becoming a value close to the start SOC value B1. The power storage system 1 brings the SOC value close to the start SOC value B1 by charging the storage battery in advance, for example, immediately after the peak cut end time A4, outside the time period A3 to A4.

Note that a setting item for setting a charging time may be provided for the control using the start SOC value B1. The charging time may be defined so as to be included in the time period A3 to A4.

(3) The discharge start SOC value B2 is an SOC value for starting discharge for storage battery protection. The discharge stop SOC value B3 is an SOC value for stopping the discharge. The power storage system 1 starts discharging when the SOC value is equal to or higher than the discharge start SOC value B2, and stops discharging when equal to or lower than the discharge stop SOC value B3.

The charging start SOC value B4 is an SOC value for starting charging. The charge stop SOC value B5 is an SOC value for stopping the charge. The power storage system 1 starts charging when the SOC value is equal to or higher than the charging start SOC value B4, and stops charging when the SOC value is equal to or lower than the charging stop SOC value B5.

The storage system 1 controls the storage battery protection when the SOC value of the storage battery reaches the discharge start SOC value B2 by charging within the time A3 to A4, or when the load power is not equal to or higher than the peak cut load A1. As long as the discharge starts. In addition, as a storage battery protection control, when the SOC value of the storage battery reaches the charge start SOC value B4 due to discharge within the time period A3 to A4, the power storage system 1 is not less than the reverse power load A2 Only start charging.

[Control processing]
FIG. 3 shows a flow of control processing including control of peak cut operation by the control unit 101 of the power storage system 1. S1 and the like indicate processing and operation steps.

(S1) In step S1, the setting unit 10 displays a setting screen as shown in FIG. 8 to the user, accepts settings of various setting items by the user's operation on the screen, and sets the setting value. Is stored in the setting information 20. The user inputs or confirms setting values of setting items such as A1 to A4 and B1 to B5 on the screen. After the set value is set in S1 and the execution of control is instructed, the peak cut operation is automatically controlled according to the set value.

(S2) In step S2, the first measuring unit 11 measures the value of the received power 52 from the power system 2 and stores it in the measurement information 21. The first measurement unit 11 measures the value of the load power 53 of the load facility 3 and stores the value in the measurement information 21. The first measuring unit 11 always measures the received power 52 and the load power 53.

(S3) In step S3, the second measurement unit 12 measures the value of the state including the closed circuit voltage (CCV), the current (i), and the temperature (K), which is the voltage of the storage battery, and the measurement. The value is stored in the measurement information 21. The second measuring unit 11 performs the above measurement at a set constant period (denoted as ΔT).

(S4) In step S4, the SOC calculation unit 13 performs the SOC calculation process at a predetermined cycle (ΔT) corresponding to the measurement cycle of S3, and continues to acquire the calculated value in real time for each cycle. The SOC calculation unit 13 uses the previous SOC value 301 included in the measurement information 21 and the SOC information 23 by S2 and S3, and the current SOC value that is the latest SOC value by the recurrence formula 300 based on the storage battery model described later and CCV verification. An SOC value 302 is calculated. The CCV verification is an estimation of voltage and SOC using the SOC-OCV characteristic table 25. The SOC information 23 is time-series information including the previous SOC value and the current SOC value. Details of the process of S4 will be described later.

(S5) In step S5, the charge / discharge control unit 14 always performs the charge / discharge control process including the peak cut operation control shown in S5-1 to S5-3 according to the set value. The charge / discharge control unit 14 charges or discharges the storage battery at a predetermined time according to the current SOC value 302 that is the latest SOC value obtained in S4 and the setting information 20.

(S5-1) In step S5-1, the charge / discharge control unit 14 performs peak cut as a control process for the peak cut operation during the period from the peak cut start time A3 to the peak cut end time A4. The storage battery group is charged and discharged so as to keep it within the range between the load A1 and the reverse power load A2.

The charge / discharge control unit 14 supplies power to the load facility 3 by discharging the storage battery when the current load power value is equal to or higher than the peak cut load A1. The SOC value of the storage battery decreases due to discharge. The charge / discharge control part 14 charges a storage battery with the received electric power 52 or the generated electric power 54, when the value of the present load electric power is below the reverse power load A2. Thereby, the electric power of a reverse power flow is reduced and the SOC value of the storage battery is increased.

(S5-2) In step S5-2, the charge / discharge control unit 14 performs the following control using the set values of A1 to A4 as the first storage battery protection control process. The charge / discharge control unit 14 prepares for the next peak cut start time A3 in advance at a time outside the peak cut end time A4 to the peak cut end time A4, for example, immediately after the peak cut end time A4. The storage battery group is charged so that the SOC value becomes the same value as the starting SOC value B1 or a value as close as possible. When the SOC value reaches the start SOC value B1 within the time period A3 to A4, the power storage system 1 stops charging and waits until the next peak cut start time A3, and after A3, the peak cut operation is performed again. Start the main operation.

(S5-3) In step S5-3, the charge / discharge control unit 14 performs the following control using the set values of B2 to B5 as the second storage battery protection control process. 1stly, the charge / discharge control part 14 starts discharge of a storage battery, when the newest SOC value becomes more than discharge start SOC value B2. This reduces the SOC value. And the charge / discharge control part 14 stops discharge of a storage battery, when the newest SOC value becomes below discharge stop SOC value B3.

Second, the charge / discharge control unit 14 starts charging the storage battery when the latest SOC value becomes equal to or lower than the charge start SOC value B4. This increases the SOC value. And the charge / discharge control part 14 stops charge of a storage battery, when the newest SOC value becomes more than charge stop SOC value B5.

The charge / discharge control unit 14 executes the control of S5-1 with the first priority and executes the control of S5-3 with the second priority. That is, as described above, the charging / discharging control unit 14 performs the charging / discharging of S5-1 when the condition of S5-1 is met within the time period A3 to A4, and meets the condition of S5-1. If the condition of S5-3 is satisfied, the charging / discharging of S5-3 is executed.

[Peak cut operation]
FIG. 4 shows an operation of peak cut operation in the conventional power storage system. The power storage system 1 of the present embodiment performs specific control based on this conventional peak cut operation.

4 (a), the horizontal axis represents time, and the vertical axis represents the load power of the load facility (unit: W). 401 indicates a set value of the peak cut load, and indicates a target level for suppressing the peak of the load power by the peak cut operation. Reference numeral 402 denotes a time and load power at a location where the load power exceeds the set value 401. Reference numeral 403 denotes the time at the location 402. In the example of FIG. 4, the load power peaks beyond the set value 401 during the time from 15:00 to 17:00 of 403. The peak cut operation suppresses the power at a peak such as 402 exceeding the set value of the peak cut load 401 based on the monitoring of the load power.

4 (b), corresponding to FIG. 4 (a), the horizontal axis indicates time, and the vertical axis indicates the electric power generated by charging and discharging the storage battery by the power storage system. Reference numeral 411 denotes charging of the storage battery by the received power from the power system in the night time zone. Reference numeral 412 indicates the discharge of the storage battery corresponding to the peak position 402 and the time 403 in the daytime time zone. In FIG. 4B, charging is shown as positive (+) and discharging is shown as negative (−).

(C) in FIG. 4 corresponds to (a) and (b) in FIG. 4, the horizontal axis indicates time, and the vertical axis indicates received power from the power system. Reference numeral 421 indicates that the peak load power is suppressed to the set value 401 by allocating the power from the charge 411 to the peak load power 402 by the discharge 412.

[SOC]
FIG. 5 shows an example of setting values of setting items (B1 to B5) related to the SOC of the storage battery in the first embodiment. The set values in FIG. 5 are examples, and differ depending on the characteristics of the storage battery used. The unit of the SOC value is%. In a certain storage battery, SOC is in a range of 0% to 100%. 511 indicates SOC = 5%. 512 indicates a range of SOC = 0% to 5%, which corresponds to a region where the deterioration of the storage battery is remarkable. 513 indicates SOC = 95%. Reference numeral 514 denotes a range of SOC = 95% to 100%, which corresponds to a region where the deterioration of the storage battery is remarkable.

With the peak cut operation, the power storage system 1 controls the load fluctuation range using the peak cut load A1 and the reverse power load A2 described above, and the SOC value is a range of SOC values corresponding to the load power, for example 511. It is limited to the range of ˜513. Accordingly, the power storage system 1 protects the SOC value of the storage battery from entering the deterioration area 512 or the area 514.

501 indicates 75% as an example of the start SOC value B1. Reference numeral 502 denotes 90% as an example of the discharge start SOC value B2. Reference numeral 503 denotes 85% as an example of the discharge stop SOC value B3. Reference numeral 504 denotes 60% as an example of the charge start SOC value B4. 505 indicates 65% as an example of the charge stop SOC value B5. Reference numeral 510 denotes a range in which a discharge start SOC value B2 of 502 is an upper threshold value and a charge start SOC value B4 of 504 is a lower threshold value.

In accompaniment with peak cut operation, the power storage system 1 performs storage battery protection control processing using the above 510 range and threshold values (B2 to B4) in addition to load fluctuation range control using A1 to A4.

[Example of peak cut operation]
FIG. 6 shows an operation example of peak cut operation by the power storage system 1 of the first embodiment. In FIGS. 6A, 6B, and 6C, the horizontal axis corresponds to time (from 0:00 to 23:00). The peak cut start time A3 is, for example, 4 o'clock, and the peak cut end time A4 is, for example, about 19:30.

(A) of FIG. 6 is charging / discharging electric power whose vertical axis is a storage battery output. In FIG. 6, charging is shown as positive (+) and discharging is shown as negative (−). The shaded area indicates an example corresponding to the main operation of the peak cut operation control (S5-1), and the dotted area indicates an example corresponding to the operation of the storage battery protection control (S5-2, S5-3). Show.

6 (B), the vertical axis represents the SOC value of the storage battery, and ranges from 0% to 611. Reference numeral 611 denotes a system failure stop SOC value, for example, 100%. B1 to B5 are the set values described above.

6 (C), the vertical axis represents the load power 53 of the load facility 3. The set value of the aforementioned peak cut load A1 and the set value of the reverse power load A2 are shown. The value of the reverse tide load A2 is negative.

FIG. 6 illustrates an example of the daily peak cut operation along the time axis. The main operation of the peak cut operation is started at 4:00, which is the peak cut start time A3. At the time of A3, the SOC value is adjusted to the above-described start SOC value B1. During the time from 5 o'clock to 8 o'clock, there is little power demand and the load power is lower than the reverse power load A2, and charging 601 is performed as an operation of peak cut operation. As a result, the SOC value rises from the starting SOC value B1.

Due to the charging 601, the SOC value exceeds the discharge start SOC value B2 around 8 o'clock indicated by tx. Thereby, the electrical storage system 1 starts the discharge 602 as the operation of the storage battery protection, and the discharge 602 is performed for a time from 9:00 to 10:00. Due to the discharge 602, the SOC value reaches the discharge stop SOC value B3 around 10:00. Thereby, the electrical storage system 1 stops the discharge 602, and after the stop, the SOC value is maintained constant.

Next, during the period from about 11:00 to 12:00, the load power increases and exceeds the peak cut load A1, and the discharge 603 is performed as an operation of the peak cut operation. As a result, the SOC value decreases during the time.

During the period from 12:00 to 13:00, there is little load demand during lunch breaks, etc., and during this time, the load power is lower than the reverse power load A2, and charging 604 is performed as an operation of peak cut operation. As a result, the SOC value increases during the time.

Next, since the load power exceeds the peak cut load A1 from 13:00 to 15:00, the discharge 605 is performed as the operation of the peak cut operation. As a result, the SOC value is lowered.

Due to the discharge 605, the SOC value is lower than the charging start SOC value B4 around 15:00 indicated by ty. Thereby, the electrical storage system 1 starts charge 606 as operation | movement of storage battery protection. The SOC value increases due to the charging 606, and the SOC value reaches the charging stop SOC value B5 around 16:30. Thereby, the power storage system 1 stops the charging 606. After stopping, the SOC value is kept constant.

The main operation of the peak cut operation ends at around 19:30, which is the peak cut end time A4. Immediately after the peak cut end time A4, the power storage system 1 starts charging 607 because the SOC value is lower than the start SOC value B1 as an operation for protecting the storage battery. For example, charging 607 is performed from about 19:30 to about 21:30, whereby the SOC value reaches the start SOC value B1. Thereafter, the SOC value is maintained at the start SOC value B1 until the peak cut start time A3 of the next day.

[SOC calculation processing]
Details of the SOC calculation processing in step S4 will be described below. First, in the SOC calculation in the conventional power storage system, the SOC calculation during operation such as peak cut is performed by a current integration method. When the SOC calculation method is current integration, measurement errors and the like of the current detector are accumulated when calculating the integrated charge amount and the integrated discharge amount. Therefore, in the process of SOC calculation for a long period of time by automatic operation, there is a high possibility that errors will increase, and it is difficult to calculate an accurate or highly accurate SOC value.

The power storage system 1 of the first embodiment performs the SOC calculation using CCV verification as in S4. Thereby, there is no accumulation and increase of errors due to the operation time as described above. Therefore, an accurate or highly accurate SOC value can be calculated. The power storage system 1 can control peak cut operation and storage battery protection to realize low loss by using this SOC value.

In S4, the SOC calculation unit 13 calculates an open circuit voltage OCV that is a voltage obtained by compensating the internal resistance and polarization component of the storage battery based on the current i, the temperature K, and the previous SOC value 301 with respect to the measured closed circuit voltage CCV. calculate. The SOC calculation unit 13 calculates the open circuit voltage OCV by the recurrence formula 300 based on the storage battery model of FIG. The SOC calculation unit 13 calculates the current SOC value 302, which is the latest SOC value, using the SOC-OCV characteristic table 25 corresponding to the temperature K with respect to the open circuit voltage OCV calculated using the above recurrence formula 300. To do.

[Storage battery model and SOC-OCV characteristics table]
The upper side of FIG. 7 shows a storage battery model used for measurement by the power storage system 1 and calculation of the SOC value of S4. The lower side of FIG. 7 shows an example of the SOC-OCV characteristic table 25 of a certain storage battery 5. In the upper storage battery model of FIG. 7, one storage battery 5 and its internal resistance and polarization component are shown. The storage battery 5 has R1 as an internal resistance, and has, as polarization components, a resistance R2 and a time constant τ2 that are first polarization components, and a resistance R3 and a time constant τ3 that are second polarization components.

V1 is a voltage due to the internal resistance R1 of the storage battery 5. V2 is a voltage due to the first polarization component. V2 is calculated from the internal resistance R2 and the time constant τ2. V3 is a voltage due to the second polarization component. V3 is calculated from the internal resistance R3 and the time constant τ3.

The storage system 1 uses the previous SOC value 301 and the temperature K, and from the table (not shown) included in the storage battery characteristic information 22, the internal resistances R2, R3 of the storage battery 5, time constants τ2, τ3, etc. Read or calculate the information. The storage battery characteristic information 22 includes, for example, a table in which values such as internal resistance corresponding to the temperature K are described.

The closed circuit voltage (CCV) is generally a voltage including a voltage due to an internal resistance of the storage battery in a state where a load is connected to the storage battery and a current flows. The closed circuit voltage CCV = V _{CCV in} FIG. 7 is a voltage including V1 to V3 in addition to the open circuit voltage OCV = V _OCV . V _CCV is the voltage of the storage battery measured during charging / discharging.

An open circuit voltage (OCV) is generally a voltage between both terminals of a storage battery in a state where no load is connected to the storage battery and no current is passed. The open circuit voltage OCV = V _{OCV in} FIG. 7 is a voltage applied to the storage battery 5 calculated by compensating the internal resistance and the polarization component, that is, removing the influence.

The recurrence formula 300 is as shown in the following formulas 1 to 4. Note that n indicates the number of times of calculation in the recurrence formula. n-1 indicates the previous value, and n indicates the current value. ΔT is a calculation cycle.

OCV (= V _OCV ) = CCV (= V _CCV ) + V1 + V2 + V3 Expression 1
V1 = R1 × i Equation 2
V2 _n = V2 _n−1 (1−ΔT / τ2) + i × R2 (ΔT / τ2) Equation 3
V3 _n = V3 _n−1 (1−ΔT / τ3) + i × R3 (ΔT / τ3) Equation 4
The SOC-OCV characteristic table 25 is a two-dimensional table having information on the open circuit voltage OCV and the temperature K. One SOC-OCV characteristic table 25 corresponding to the temperature K of a certain storage battery 5 shows the characteristic of the relationship between the SOC value and the open circuit voltage OCV at a certain temperature K. In the SOC-OCV characteristic table 25 of FIG. 7, the horizontal axis represents the open circuit voltage OCV, and the vertical axis represents the SOC value. In the curve of the example of FIG. 7, the SOC increases with a high slope in the region where the OCV is low, the SOC increases with a constant or gentle slope in the region where the OCV is medium, and the SOC increases again with a high slope in the region where the OCV is high. To increase.

[Setting screen example]
FIG. 8 shows an example of a setting screen in the first embodiment. In this screen, reference numeral 801 denotes an item that allows the user to select one of a plurality of setting modes. The user can use a plurality of setting modes separately for each application target. In the setting mode, a user can set a name, an application target, and the like.

802 shows a table that displays the contents of various setting items that are the contents of the setting mode selected in 801. In the table 802, as shown in rows # 1 to # 9, the setting items A1 to A4 and B1 to B5 are displayed. For each setting item such as A1, a description of the contents and the current setting value are displayed. In addition, for each setting item such as A1, a value can be input or selected by the user in a setting value field indicated by 803. Reference numeral 804 denotes a button for executing setting and setting change in the state of the setting value 803 in the table 802.

In addition, other screens (not shown) can be set with a setting mode to be applied to a calendar date or the like as an operation schedule. The operation is automatically executed according to the set schedule.

The setting item setting interface is not limited to the screen example of FIG. For example, another example of the screen may display an indicator related to the SOC as in FIG. 6, and each setting value may be set by a vertical slide. As another example of the screen, similarly to FIG. 4 and FIG. 6, a graph of transition of values on the time axis may be displayed, and setting values in the graph may be settable. The screen may be displayed on an operation panel of a control panel constituting the power storage system 1 or may be displayed on an information processing apparatus connected to the control panel.

[Comparison of control methods]
9A and 9B supplementarily show (A) the outline of control of the load fluctuation range in the above-described peak cut operation by the power storage system of the first embodiment, and (B) the control of load fluctuation by the conventional power storage system. The outline of is shown.

The control of the load fluctuation range of the power storage system 1 according to the first embodiment of FIG. 9A is performed so that the actual load power and the corresponding SOC are within the load power threshold value (A1, A2) range 900. This is a method for controlling charging and discharging. Reference numeral 901 denotes a set value corresponding to the above-described peak cut load A1 as the upper limit threshold of the range 900. Reference numeral 902 denotes a setting value corresponding to the above-described reverse power load A2 as a lower limit threshold value of the range 900. Reference numeral 911 denotes a location where the load power exceeds the upper limit threshold value 901, and discharge is performed at this location 911. Reference numeral 912 denotes a portion where the load power exceeds the lower limit threshold value 902, and charging is performed at this portion 912.

9B is a method of controlling charging / discharging so that the load power follows the single threshold value 920 related to the load power. When 921 exceeds the

threshold value

920, 922 indicates when the threshold value 920 is below. In the control of the conventional example, control is performed so that the load power follows the threshold 920. However, since the actual load power and the corresponding SOC fluctuate, they cannot be maintained at the same value as the threshold 920. That is, in the control of the conventional example, the state where charging or discharging is almost always continued.

In the power storage system of the first embodiment, as shown in (A), control is performed so as to suppress the threshold value to 900, so that loss due to charging and discharging is small, which is advantageous with respect to the life of the storage battery. Since the conventional example is not controlled within the range of the threshold as shown in (B), the loss due to charging / discharging is large, which is disadvantageous with respect to the life of the storage battery.

[Effects]
As described above, according to the power storage system 1 of the first embodiment, it is possible to suppress the shortening of the life of the storage battery by reducing the loss by suitable control of the peak cut operation. According to the power storage system 1 of the first embodiment, since the capacity is adjusted by the discharge start SOC value and the charge start SOC value, the number of storage batteries can be reduced or the capacity of the storage battery can be reduced during system construction. Overall, a low-cost system can be realized. In addition, the user can set a control setting value on the screen.

<Embodiment 2>
A power storage system 1 according to the second embodiment will be described. The power storage system 1 of the second embodiment has a function related to control of peak shift operation in addition to the function related to control of peak cut operation of the first embodiment. The power storage system 1 according to the second embodiment performs switching to the selected mode between the peak cut operation mode and the peak shift operation mode based on the selection and setting by the user. Hereinafter, a configuration different from the first embodiment in the second embodiment will be described.

[Peak shift operation]
FIG. 10 shows an operation of peak shift operation in the conventional power storage system. The peak shift operation of power storage system 1 of the second embodiment is based on the peak shift operation of this conventional example. In peak shift operation, load power is not monitored, and charging and discharging are performed at different predetermined time zones. That is, in the peak shift operation, charging is performed during a predetermined nighttime period when the power demand is low, and discharging is performed during a predetermined daytime period when the power demand is high.

10A, the horizontal axis represents time, and the vertical axis represents the load power of the load facility (unit: W). Reference numeral 501 denotes a set value of the peak shift load. This set value 501 indicates a reference level for suppressing load power by peak shift operation. Reference numeral 502 denotes a location including a peak where the load power exceeds the set value 501 and a location where the power demand is high. Reference numeral 503 denotes a time zone including a portion 502 where the load power exceeds the set value 501. In the example of FIG. 10, the load power includes a portion where the load power exceeds the set value 501 in the time zone from 14:00 to 18:00 of 503, and the load power fluctuates for each individual time.

10B corresponds to FIG. 10A, the horizontal axis indicates time, and the vertical axis indicates electric power due to charging / discharging of the storage battery by the power storage system. Reference numeral 511 denotes charging of the storage battery with a constant output by the received power from the power system in a predetermined night time zone set for peak shift and having a low power demand. Reference numeral 512 denotes power supply to the load facility by discharging the storage battery with a constant output in a predetermined daytime time zone that is set for peak shift corresponding to the time zone 503 and has a large power demand.

(C) in FIG. 10 corresponds to (a) and (b) in FIG. 10, and the horizontal axis represents time and the vertical axis represents received power from the power system. Reference numeral 521 indicates that the load power is suppressed to a set value 501 or less by applying the power of the charge 511 to the time zone 503 by the discharge 512. The same power is allocated at each time in the 503 time zone. As described above, the load power in the time zone 503 including the peak is reduced by the peak shift operation, and the received power is adjusted to be close between the time zone of the charge 511 and the time zone of the discharge 512.

[Control functions and setting items for peak shift operation]
The power storage system 1 of Embodiment 2 further includes a peak shift control unit in addition to the charge / discharge control unit 14 of FIG. The peak shift control unit controls the peak shift operation using the set value of the setting item for controlling the peak shift operation. The power storage system 1 according to the second embodiment further includes a peak shift operation control process step by a peak shift control unit in the control process flow of FIG. Although not shown, this is step S6. In S1, a value of a setting item for controlling peak shift operation is set, and execution of the peak shift operation is instructed. In the case of executing control in the peak shift operation mode, step S6 of charge / discharge control processing for additional peak shift operation is performed instead of S5. This additional step S6 includes step S6-1 of the peak shift operation control process instead of S5-1, and step S6-2 of the first storage battery protection control process instead of S5-2.

The power storage system 1 of the second embodiment has the following C1 to C6 as setting items to be added to the setting items of the first embodiment regarding the control of the peak shift operation.

C1: Charging start time C2: Charging end time C3: Charging output [W]
C4: Discharge start time C5: Discharge end time C6: Discharge output [W].

The charge start time C1 is a start time of a predetermined time zone for charging at a constant output, and the charge end time C2 is an end time of the time zone. The charging output C3 is a constant output power in the time zone. The discharge start time C4 is a start time of a predetermined time period for discharging at a constant output, and the discharge end time C5 is an end time of the time period. The discharge output C6 is constant output power in the time zone.

In step S6-1 of the peak shift operation control process, the power storage system 1 of the second embodiment charges the storage battery group with a constant output during a predetermined charging time period according to the setting items C1 to C3, and sets the setting item C4. Through C6, the storage battery group is discharged at a constant output during a predetermined discharge time zone. The power storage system 1 of the second embodiment applies the same load fluctuation range control as that of the first embodiment during the peak shift operation during the predetermined charging time zone and the predetermined discharging time zone. That is, the power storage system 1 of the second embodiment discharges when the load power is equal to or higher than the peak cut load A1 within a predetermined charging time zone, and the reverse power load A2 within the predetermined discharging time zone. If it is below, charge. This prevents the load power from exceeding the peak cut load A1 or the reverse power load A2.

The power storage system 1 of the second embodiment uses a set value similar to the start SOC value B1 of the first embodiment as a step S6-2 of the first storage battery protection control process, and uses a predetermined discharge time zone (C4 The charging is performed in advance so that the SOC value approaches the starting SOC value B1 under the condition that the load is low during the time until the start of the predetermined charging time period (C1 to C2) after the end of .about.C5). Do. For example, immediately after the discharge end time C5, the power storage system 1 starts charging according to the situation, and stops charging when the SOC value reaches the start SOC value B1.

FIG. 11 shows an example of a setting screen relating to peak shift operation control by the setting unit 10 according to the second embodiment. In this screen, reference numeral 1101 denotes an item that allows the user to select one of a plurality of setting modes. A table 1102 displays the contents of various setting items, which are the contents of the setting mode selected in 1101. In the table 1102, the setting items C1 to C6 described above are displayed as shown in rows # 1 to # 6. Although not shown, the same setting items as the above-described A1, A2, B1, etc. are displayed. A value can be input or selected by the user in the setting value field 1103. Reference numeral 1104 denotes a button for executing setting and setting change in the state of the setting value 1103 in the table 1102.

As described above, according to the second embodiment, also in the case of the peak shift operation, similarly to the control of the peak cut operation of the first embodiment, the life of the storage battery can be shortened by reducing the loss by suitable control. Can be suppressed.

As described above, the present invention has been specifically described based on the embodiment. However, the present invention is not limited to the above-described embodiment, and needless to say, various modifications can be made without departing from the scope of the invention.

The present invention can be used as a power storage system for various load facilities including offices and factories.

DESCRIPTION OF SYMBOLS 1 ... Power storage system, 2 ... Electric power system, 3 ... Load facilities, 4 ... Solar power generation system, 5 ... Storage battery, 10 ... Setting part, 11 ... 1st measurement part, 12 ... 2nd measurement part, 13 ... SOC calculating part , 14 ... charge / discharge control unit, 15 ... peak cut control unit, 16 ... first protection control unit, 17 ... second protection control unit, 20 ... setting information, 21 ... measurement information, 22 ... storage battery characteristic information, 23 ... SOC Information, 25 ... SOC-OCV characteristic table, 50 ... Power measurement, 52 ... Received power, 53 ... Load power, 54 ... Generated power, 62 ... Charge, 63 ... Discharge, 64 ... Charge, 65 ... Power supply, 66 ... Reverse power flow , 71 ... control panel housing part, 72 ... storage battery panel housing part, 101 ... control part, 102 ... storage part, 103 ... input / output part.

Claims

A control device connected to the power system and the load facility, and a plurality of storage batteries connected to the control device,
The controller is
A setting unit that sets the value of a setting item for control based on a user's operation;
A measuring unit that measures a value including a received power from the power system, a load power of the load facility, a voltage, a current, and a temperature of the storage battery, and
A charge / discharge control unit that controls charging and discharging of the plurality of storage batteries, including control of peak cut operation that suppresses the peak of load power of the load facility by charging and discharging the plurality of storage batteries, and
The setting unit sets a value of a setting item including a start time, an end time, a first load power, and a second load power of the peak cut operation,
The charge / discharge control unit is configured so that the load power falls within a range between the first load power and the second load power in a time from the start time to the end time of the set peak cut operation. A storage system that discharges the storage battery to supply power to the load facility when load power is equal to or higher than the first load power, and charges the storage battery when load power is equal to or lower than the second load power.
The power storage system according to claim 1,
The controller is
An SOC calculation unit that calculates an SOC value that is the latest charging rate of the storage battery according to charging and discharging of the storage battery using a measured value of the state of the storage battery,
The setting unit sets a start SOC value as the setting item,
In accordance with the SOC value, the charge / discharge control unit is configured in advance before the start time so that the SOC value becomes equal to or approaches the start SOC value at the set peak cut operation start time. A power storage system for charging the storage battery.
The power storage system according to claim 1,
The controller is
An SOC calculation unit that calculates an SOC value that is the latest charging rate of the storage battery according to charging and discharging of the storage battery using a measured value of the state of the storage battery,
The setting unit sets a discharge start SOC value and a discharge stop SOC value as the setting items,
The charge / discharge control unit starts discharging the storage battery when the SOC value becomes equal to or higher than the discharge start SOC value during the peak cut operation time, and the SOC value is set to the discharge stop SOC. An electricity storage system that stops discharging the storage battery when the value becomes lower than or equal to the value.
The power storage system according to claim 1,
The controller is
An SOC calculation unit that calculates an SOC value that is the latest charging rate of the storage battery according to charging and discharging of the storage battery using a measured value of the state of the storage battery,
The setting unit sets a charge start SOC value and a charge stop SOC value as the setting items,
The charge / discharge control unit starts charging the storage battery when the SOC value is equal to or lower than the charge start SOC value during the peak cut operation time, and the SOC value is the charge stop SOC. A power storage system that stops charging the storage battery when the value exceeds the value.
A control device connected to the power system and the load facility, and a plurality of storage batteries connected to the control device,
The controller is
A setting unit that sets the value of a setting item for control based on a user's operation;
A measuring unit that measures a value including a received power from the power system, a load power of the load facility, a voltage, a current, and a temperature of the storage battery, and
A charge / discharge control unit that controls charging and discharging of the plurality of storage batteries, including control of peak shift operation that suppresses the peak of load power of the load facility by charging and discharging the plurality of storage batteries in a predetermined time zone; Have
The setting unit includes a charge time zone start time, end time, and constant output power, a discharge time zone start time, end time, constant output power, and first load power in the peak shift operation. And setting the value of the setting item including the second load power,
The charge / discharge control unit is configured to control the peak shift operation so that the load power falls within a range between the first load power and the second load power in the charge time zone and the discharge time zone. In addition, when the load power is greater than or equal to the first load power, the storage battery is discharged to supply power to the load facility, and when the load power is less than or equal to the second load power, the storage battery is charged. system.
The power storage system according to claim 5, wherein
The controller is
An SOC calculation unit that calculates an SOC value that is the latest charging rate of the storage battery according to charging and discharging of the storage battery using a measured value of the state of the storage battery,
The setting unit sets a start SOC value as the setting item,
In accordance with the SOC value, the charge / discharge control unit is configured to discharge the discharge so that the SOC value becomes equal to or approaches the start SOC value at a start time of the charging time zone of the set peak shift operation. A storage system in which the storage battery is charged in advance after the end time of the time period and before the start time of the charging time period.
The power storage system according to any one of claims 2 to 4 and 6,
As information indicating the characteristics of the storage battery, a storage battery information storage unit that stores information indicating the relationship between the SOC and the open circuit voltage according to the temperature of the storage battery,
The measurement unit measures the value of the state including the closed circuit voltage, current, and temperature of the storage battery at a predetermined cycle,
The SOC calculation unit calculates the open circuit voltage of the storage battery using the closed circuit voltage and current of the storage battery and the previous SOC value, and determines the relationship between the open circuit voltage and the SOC and the open circuit voltage according to the temperature. The power storage system that calculates the current SOC value using the information shown.